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Title: Noninvasive myographical assessments following unaccustomed resistance exercise.
Creator: Boone, Carleigh, Fragala, Maren, Hoffman, Jay, Stout, Jeffrey, Fukuda, David, University of Central Florida
Abstract / Description: Traditionally, post-exercise muscular alterations have been examined using invasive techniques that lack the ability to single out individual muscle groups. Sonomyography, tensiomyography, and electrical impedance myography allow for noninvasive skeletal muscle assessment. This project aimed to examine changes in muscle contractility and composition that occur in the early stages of recovery following unaccustomed exercise. METHODS: Twenty-one untrained adults (21.9 (&)#177; 1.9 y) performed...
Show moreTraditionally, post-exercise muscular alterations have been examined using invasive techniques that lack the ability to single out individual muscle groups. Sonomyography, tensiomyography, and electrical impedance myography allow for noninvasive skeletal muscle assessment. This project aimed to examine changes in muscle contractility and composition that occur in the early stages of recovery following unaccustomed exercise. METHODS: Twenty-one untrained adults (21.9 (&)#177; 1.9 y) performed exercise (-) 10 (&)#215; 10 maximal eccentric knee extensions (-) with their nondominant leg. For each repetition, participants moved through 90(&)deg; range of motion at 90(&)deg;•s-1 with a passive return to the start position. Each set was separated by 60 seconds of rest. Sonomyography, tensiomyography, electrical impedance myography, and maximal isometric contractions of the knee extensors (RF (&) VL) of both legs were performed before (BL), immediately after (IP), and 24 hours post-exercise (24H). RESULTS: Peak torque and rate of torque development were unaltered in response to the eccentric protocol. Significant limb (&)#215; time interactions were noted for reactance, phase angle, and delay time of the exercised VL, and echo intensity of the exercised RF. Compared to the dominant leg, the nondominant leg displayed significantly greater changes (p (<) 0.05) in VL delay time and RF echo intensity at IP. Following exercise, bilateral alterations were identified for reactance, phase angle, maximal displacement, delay time, contraction velocity, cross-sectional area, and thickness of the RF, as well as resistance, echo intensity, cross-sectional area, and thickness of the VL. No between-sex differences were noted in response to exercise. CONCLUSIONS: In the absence of performance decrements, sonomyography, tensiomyography, and electrical impedance myography successfully detected acute changes in skeletal muscle composition and function following an acute bout of eccentric exercise in untrained men and women. While the exercised leg exhibited specific responses in delay time and echo intensity, bilateral changes are theorized to have occurred due to contralateral stabilization of the non-exercised leg. The current results suggest that different muscle actions (i.e., eccentric and isometric) promote similar consequences to muscle strength, size, echogenicity, contractility, and bioelectrical properties.
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Date Issued: 2019
Identifier: CFE0007432, ucf:52731
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0007432

Title: CHANGES IN RUNNING AND MULTIPLE OBJECT TRACKING PERFORMANCE DURING A 90-MINUTE INTERMITTENT SOCCER PERFORMANCE TEST (iSPT). A PILOT STUDY.
Creator: Girts, Ryan, Wells, Adam, Stout, Jeffrey, Fukuda, David, Hoffman, Jay, University of Central Florida
Abstract / Description: Multiple object tracking (MOT) is a cognitive process that involves the active processing of dynamic visual information. In athletes, MOT speed is critical for maintaining spatial awareness of teammates, opponents, and the ball while moving at high velocities during a match. Understanding how MOT speed changes throughout the course of a competitive game may enhance strategies for maintaining optimal player performance. The objective of this study was to examine changes in MOT speed and...
Show moreMultiple object tracking (MOT) is a cognitive process that involves the active processing of dynamic visual information. In athletes, MOT speed is critical for maintaining spatial awareness of teammates, opponents, and the ball while moving at high velocities during a match. Understanding how MOT speed changes throughout the course of a competitive game may enhance strategies for maintaining optimal player performance. The objective of this study was to examine changes in MOT speed and running performance during a 90-minute intermittent soccer performance test (iSPT). A secondary purpose was to examine the relationship between aerobic capacity and changes in MOT speed.Seven competitive female soccer players age: 20.4 (&)#177; 1.8 y, height: 166.7 (&)#177; 3.2 cm, weight: 62.4 (&)#177; 4.0 kg, VO2max: 45.8 (&)#177; 4.6 ml/kg/min-1) completed an intermittent soccer performance test (iSPT) on a Curve(TM) non-motorized treadmill (cNMT). The iSPT was divided into two 45-minute halves with a 15-minute halftime [HT] interval, and consisted of six individualized velocity zones. Velocity zones were consistent with previous time motion analyses of competitive soccer matches and based upon individual peak sprint speeds (PSS) as follows: standing (0% PSS, 17.8% of iSPT), walking (20% PSS, 36.4% of iSPT), jogging (35% PSS, 24.0% of iSPT), running (50% PSS, 11.6% of iSPT), fast running (60% PSS, 3.6% of iSPT), and sprinting (80% PSS, 6.7% of iSPT). Stand, walk, jog and run zones were combined to create a low-speed zone (LS). Fast run and sprint zones were combined to create a high-speed zone (HS). MOT speed was assessed at baseline (0 min.) and three times during each half of the iSPT. Dependent t-tests and Pearson correlation coefficients were utilized to analyze the data. Across 15-minute time blocks, significant decreases in distance covered and average speed were noted for jogging, sprinting, low-speed running, high-speed running, and total distance (p's (<) 0.05). Players covered significantly less total distance during the second half compared to the first (p = 0.025). Additionally, significant decreases in distance covered and average speed were observed during the second half for the sprint and HS zones (p's ? 0.008). No significant main effect was noted for MOT speed across 15-minute time blocks. A trend towards a decrease in MOT speed was observed between halves (p = 0.056). A significant correlation was observed between the change in MOT speed and VO2max (r = 0.888, p = 0.007). The fatigue associated with 90 minutes of soccer specific running negatively influenced running performance during the second half. However, increased aerobic capacity appears to be associated with an attenuation of cognitive decline during 90-minutes of soccer specific running. Results of this study indicate the importance of aerobic capacity on maintaining spatial awareness during a match.
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Date Issued: 2018
Identifier: CFE0007183, ucf:52290
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0007183

Title: Examining Work-To-Rest Ratios To Optimize Upper Body Sprint Interval Training.
Creator: Lamonica, Michael, Fukuda, David, Hoffman, Jay, Stout, Jeffrey, Fragala, Maren, University of Central Florida
Abstract / Description: The primary purpose of this study was to compare the metabolic influence of varying work-to-rest ratios during upper body sprint interval training (SIT). Forty-two recreationally trained men were randomized into one of three training groups [10s work bouts with two minutes of rest (10:2, n = 11) or four minutes of rest (10:4, n = 11), or 30s work bouts with four minutes of rest (30:4, n = 10)] or a control group (CON, n = 10). Participants underwent six training sessions over two weeks with...
Show moreThe primary purpose of this study was to compare the metabolic influence of varying work-to-rest ratios during upper body sprint interval training (SIT). Forty-two recreationally trained men were randomized into one of three training groups [10s work bouts with two minutes of rest (10:2, n = 11) or four minutes of rest (10:4, n = 11), or 30s work bouts with four minutes of rest (30:4, n = 10)] or a control group (CON, n = 10). Participants underwent six training sessions over two weeks with four to six 'all-out' sprints. During pre- and post-intervention visits, participants underwent a graded exercise test to determine maximal oxygen consumption (V?O2peak) and peak power output (PPO), four constant-work rate trials to determine critical power (CP), anaerobic working capacity (W'), and electromyographic fatigue threshold (EMGFT), and an upper body Wingate test to determine peak power (PP), mean power (MP), and total work (TW). Oxygen consumption and blood lactate during the Wingate test generated estimates of oxidative, glycolytic, and ATP-PCr energy system provisions. An analysis of covariance was performed on all testing measurements collected at post with the associated pre-values used as covariates. V?O2peak was greater in 30:4 (p = .007) and 10:2 (p = .036) compared to CON and PPO was greater in 30:4 than CON (p = .007). No differences were observed between groups in CP (p = .530), W' (p = .900), EMGFT (p = .692), PP (p = .692), MP (p = .290), or TW (p = .291). Relative energy contribution (p = .026) and energy expenditure (p = .019) of the ATP-PCr energy system was greater in 10:4 compared to CON. SIT protocols with larger work-to-rest ratios induce enhanced aerobic adaptions, whereas smaller work-to-rest ratios may enhance ATP-PCr utilization in the upper body over a short-term two-week intervention.
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Date Issued: 2018
Identifier: CFE0007036, ucf:51978
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0007036

Title: The Effects of Phosphatidylserine on Reaction Time and Cognitive Function Following an Exercise Stress.
Creator: Wells, Adam, Hoffman, Jay, Fragala, Maren, Stout, Jeffrey, University of Central Florida
Abstract / Description: Phosphatidylserine (PS) is an endogenously occurring phospholipid that has been shown to have cognition and mood enhancing properties in humans, possibly through its role as an enzyme co-factor in cellular signal transduction. Specifically, PS has been identified as activator of classical isoforms of protein kinase C, an enzyme known to be involved in the growth and differentiation of neural cells, and is therefore thought to play a role in the protection of neurons.The purpose of this study...
Show morePhosphatidylserine (PS) is an endogenously occurring phospholipid that has been shown to have cognition and mood enhancing properties in humans, possibly through its role as an enzyme co-factor in cellular signal transduction. Specifically, PS has been identified as activator of classical isoforms of protein kinase C, an enzyme known to be involved in the growth and differentiation of neural cells, and is therefore thought to play a role in the protection of neurons.The purpose of this study was to examine the effects of supplementation with PS and caffeine on measures of cognition, reaction time and mood prior to and following an exercise stress. Twenty, healthy, resistance trained males (17) and females (3) (mean (&)#177; SD; age: 22.75 (&)#177; 3.27 yrs; height: 177.03 (&)#177; 8.44cm; weight: 78.98 (&)#177; 11.24kg; body fat%: 14.28 (&)#177; 6.6), volunteered to participate in this randomized, double-blind, placebo-controlled study. Participants were assigned to a PS group (400mg/day PS; 100mg/day caffeine, N=9) or PL (16g/day Carbs, N=11) delivered in the form of 4 candy chews identical in size, shape and color. Subjects performed an acute bout of full body resistance exercise, prior to (T1) and following 14 days of supplementation (T2). Measures of reaction time (Dynavision(&)#174; D2 Visuomotor Training Device), cognition (Serial Subtraction Test, SST), and mood (Profile of Mood States, POMS) were assessed immediately before and following resistance exercise in both T1 and T2. Data was analyzed using two-way ANCOVA and repeated measures ANOVA.Supplementation with 400mg PS and 100mg caffeine did not have a significant impact upon measures of reaction time or cognition between groups at baseline or following acute resistance exercise. However, there was a non-significant trend to the attenuation of fatigue between groups, following acute resistance exercise (p = 0.071). Interestingly, our data suggests that acute resistance exercise alone may improve cognitive function.Although more research is necessary regarding optimal dosage and supplementation duration, the current findings suggest that supplementation 400mg/day PS with 100mg/day caffeine may attenuate fatigue following acute resistance exercise. It is possible that the lack of significance may be the result of both an inhibition of the PS activated pathway and a withdrawal effect from caffeine.
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Date Issued: 2012
Identifier: CFE0004457, ucf:49325
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0004457

Title: Evaluation of Echogenicity Within and Between Ultrasonographic Images of the Vastus Lateralis.
Creator: Varanoske, Alyssa, Fukuda, David, Stout, Jeffrey, Hoffman, Jay, University of Central Florida
Abstract / Description: PURPOSE: The purpose of this study was to examine the echo intensity (EI) values of different ultrasound (US) images of the vastus lateralis (VL) using panoramic imaging in the transverse plane (PTI) and still imaging in the longitudinal plane (SLI). Secondary purposes of this study were to examine VL homogeneity and to determine relationships between subcutaneous adipose tissue thickness (SubQ) adjacent to the muscle and EI. METHODS: Twenty-four recreationally-trained collegiate males (20.2 ...
Show morePURPOSE: The purpose of this study was to examine the echo intensity (EI) values of different ultrasound (US) images of the vastus lateralis (VL) using panoramic imaging in the transverse plane (PTI) and still imaging in the longitudinal plane (SLI). Secondary purposes of this study were to examine VL homogeneity and to determine relationships between subcutaneous adipose tissue thickness (SubQ) adjacent to the muscle and EI. METHODS: Twenty-four recreationally-trained collegiate males (20.2 (&)#177; 1.6 years; height: 178.1 (&)#177; 6.6 cm; weight: 82.2 (&)#177; 13.4 kg) participated in this investigation. EI, cross-sectional area (CSA), muscle thickness (MT), and SubQ of the VL were assessed in the dominant limb (DOM) via three PTI and SLI. The best PTI was divided into three compartments of equal horizontal length (tertiles) to examine EI homogeneity. RESULTS: A repeated-measures ANOVA revealed a significant main effect for image/tertile between measures of EI (p (<) 0.001). The EI of PTI (57.976 (&)#177; 8.806 AU) was significantly lower than EI of SLI (65.453 (&)#177; 11.023 AU) (p = 0.002), however significant positive correlations existed between the two (r = 0.681; p (<) 0.001). Additionally, the EI of the SLI was significantly greater than the EI of the lateral tertile (58.717 (&)#177; 9.877 AU) (p = 0.001) and the EI of the posterior tertile (56.354 (&)#177; 9.887 AU) (p = 0.002). Although there was no significant difference between EI of the SLI and EI of the anterior tertile (59.065 (&)#177; 9.126 AU), a trend towards a significant difference was shown (p = 0.051). No significant differences in EI values between tertiles were identified. Significant differences in MT existed between PTI and SLI (PTI: 2.178 (&)#177; 0.367 cm; SLI: 2.015 (&)#177; 0.397 cm; p = 0.003), however MT values from PTI and SLI were significantly positively correlated with one another (r = 0.809, p (<) 0.001). Significant differences in SubQ existed between PTI and SLI (PTI: 0.217 (&)#177; 0.167 cm; SLI: 0.316 (&)#177; 0.225 cm; p (<) 0.001), however SubQ values from PTI and SLI were significantly positively correlated with one another (r = 0.915, p (<) 0.001). No relationship between EI and SubQ from either image was found (PTI and SubQ: r = -0.067, p = 0.754; SLI and SubQ: r = -0.114, p = 0.597). SLI yielded slightly lower standard errors of measurement (SEM) and coefficients of variation (CV), indicating better precision compared to PTI. CONCLUSIONS: EI of the VL appears to be homogeneous as assessed in a PTI in recreationally-trained collegiate males. Additionally, PTI and SLI yield different EI, CSA, MT, and SubQ values, but these values are highly correlated. The use of SLI requires less time, equipment, and technical expertise, and therefore may be advantageous for use in future studies.
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Date Issued: 2016
Identifier: CFE0006193, ucf:51117
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0006193

Title: Effects of an Acute High-Volume Isokinetic Intervention on Inflammatory and Strength Changes: Influence of Age.
Creator: Gordon, Joseph, Hoffman, Jay, Stout, Jeffrey, Fukuda, David, University of Central Florida
Abstract / Description: PURPOSE: The purpose of this study was to compare the effects of a high volume isokinetic intervention on lower body strength and inflammation, as well as markers of muscle damage in the subsequent 48 hours between younger and middle-aged men. METHODS: 19 healthy, recreationally trained men were randomly assigned to two groups, younger adults (YA: 21.8 (&)#177; 2.0 y; 90.7 (&)#177; 11.6 kg; 21.5 (&)#177; 4.1 % body fat), or middle-aged adults (MA: 47.0 (&)#177; 4.4 y; 96.0 (&)#177; 21.5; 24.8...
Show morePURPOSE: The purpose of this study was to compare the effects of a high volume isokinetic intervention on lower body strength and inflammation, as well as markers of muscle damage in the subsequent 48 hours between younger and middle-aged men. METHODS: 19 healthy, recreationally trained men were randomly assigned to two groups, younger adults (YA: 21.8 (&)#177; 2.0 y; 90.7 (&)#177; 11.6 kg; 21.5 (&)#177; 4.1 % body fat), or middle-aged adults (MA: 47.0 (&)#177; 4.4 y; 96.0 (&)#177; 21.5; 24.8 (&)#177; 6.3 % body fat). Both groups reported to the human performance laboratory (HPL) on four separate occasions. On the first visit (D1), anthropometric assessment, as well as a familiarization session with the isokinetic dynamometer, was performed. A muscle damaging protocol (HVP) was performed on the second visit (D2) consisting of 8 sets of 10 repetitions at 60(&)deg;(&)#183;sec-1 on the isokinetic dynamometer. An assessment protocol (AP) was performed to assess performance decrements between the YA and MA groups. For this protocol, a maximal voluntary isometric contraction (MVIC) was performed, as well as 3 isokinetic kicks at 2 different speeds (240(&)deg;(&)#183;sec-1 and 60(&)deg;(&)#183;sec-1). For the MVIC, values for peak torque (PKT), average torque (AVGT), rate of torque development at 100 ms (RTD100), and 200 ms (RTD200) were recorded. For the isokinetic kicks at 240(&)deg;(&)#183;sec-1 (ISK240) and 60(&)deg;(&)#183;sec-1 (ISK60), values were also recorded for peak torque (PKT), average torque (AVGT), as well as peak power (PP), and average power (AVGP). The AP was performed before the HVP (BL), immediately after the HVP (IP), 120 minutes after the HVP (120P), as well as one (24H) and two (48H) days following the HVP. Blood draws were also taken at BL, IP, 24H, and 48H, as well as 30 minutes (30P), and 60 minutes (60P) following the HVP to assess circulating levels of creatine kinase (CK), myoglobin (Mb), c-reactive protein (CRP), and interleukin 6 (IL-6). Ultrasound assessment was also performed at BL and IP as well to assess changes in muscle morphology as a result of the intervention. Performance, blood, and ultrasound markers were analyzed using a repeated measures ANOVA to observe between group comparisons for all of the outcome variables. RESULTS: There were no group differences observed for isometric or isokinetic peak torque or average torque, nor were there differences in isokinetic peak power or average power between the two groups as a result of the intervention. There were, however, differences in the pattern for rate of torque development at 100 ms and 200 ms between the two groups. RTD 100 was decreased at IP and 48H in YA, with MA showing decreases at IP, but also 120P and 24H unlike YA. RTD200 was decreased at all time points in YA, while MA was decreased at IP, 24H, and 48H, but not 120P. For markers of muscle damage and inflammation, there were no differences in the response of Mb, CK, CRP, or IL-6 between groups. CONCLUSIONS: Age does not appear to be a driving factor in the inflammatory or muscle damage response from a high volume isokinetic intervention. Though changes in peak torque and average torque from a high volume isokinetic intervention do not seem to differ between younger and middle-aged adults, the rate of torque production at 100ms and 200ms is different between groups. This suggests that while recovery to average or maximal strength after an exercise bout may not be affected greatly by age, the rate of neuromuscular recovery from exercise may be primarily affected by other factors such as training status.
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Date Issued: 2017
Identifier: CFE0006594, ucf:51259
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0006594

Title: Effects of a 10-Week Introductory Judo Course on Postural Control During Reactionary Bilateral Gripping Task With Varied Stances and Lower Body Power Performance.
Creator: Muddle, Tyler, Fukuda, David, Hoffman, Jay, Stout, Jeffrey, University of Central Florida
Abstract / Description: PURPOSE: The purpose of the present study is twofold: 1.) Examine the effects of 10-weeks of an introductory judo course on postural control during maximal bilateral isometric handgrip testing using different stance conditions and lower body power performance, and 2.) To analyze the relationship between maximal bilateral handgrip exertions on postural control during varied stance conditions. METHODS: Twenty recreationally active men and women divided into two an experimental group, (JDO) (n =...
Show morePURPOSE: The purpose of the present study is twofold: 1.) Examine the effects of 10-weeks of an introductory judo course on postural control during maximal bilateral isometric handgrip testing using different stance conditions and lower body power performance, and 2.) To analyze the relationship between maximal bilateral handgrip exertions on postural control during varied stance conditions. METHODS: Twenty recreationally active men and women divided into two an experimental group, (JDO) (n = 10; 21.70 (&)#177; 3.83 y; 169.91 (&)#177; 6.01 cm; 73.89 (&)#177; 12.10 kg; 19.01 (&)#177; 8.06% BF), and a control group, (CON) (n = 10; 21.50 (&)#177; 2.84 y; 170.06 (&)#177; 8.28 cm; 76.62 (&)#177; 12.03 kg; 22.41 (&)#177; 6.64% BF), participated in this study. Both groups completed pre-testing, performing nine randomly assigned experimental trials measuring center of pressure (COP) variables during the performance of a bilateral reactionary gripping task using varied stance conditions. Each trial consisted of bilateral maximal voluntary contractions (MVC) measured simultaneously with a handgrip dynamometer, three times with a neutral (N), dominant foot forward (D), and non-dominant (ND) foot forward stance. Furthermore, participants performed three bilateral countermovement jumps (CMJ) trials. All trials were completed while standing on a portable force platform, which was used, in conjunction with corresponding software, to track COP amplitude in the mediolateral (COPML) and anteroposterior (COPAP) directions, COP mean velocity (MV), and COP area (AREA) while gripping the dynamometer, and ground reaction forces, peak force (CMJPKF), peak power (CMJPP), and rate of power development (CMJRPD), during CMJ performance. Subjects were instructed to grasp the dynamometers as forcefully as possible for ?5-sec during each trial. All trials were separated by a recovery period of 60-sec. A Waterloo Handedness and Footedness Questionnaire was used to determine subject upper and lower body laterality. Participants repeated the testing protocol following the conclusion of the 10-week course. RESULTS: No significant interactions were observed in MVC strength of the DOM and NON hands during any of the three stance conditions following the 10-week judo course. Furthermore, no significant interactions were observed for any of the COP variables. However, a significant main effect of stance was observed for COPML, MV, and AREA. Results did reveal that CMJPP significantly improved in the JDO group (PRE: 3584.70 (&)#177; 716.59W - POST: 3750.10 (&)#177; 699.61W) following the 10-week judo course, while no change was observed in the CON group (PRE: 3693.10 (&)#177; 1083.77W (-) POST: 3654.40 (&)#177; 1023.94W). However, no change was seen in CMJPKF or CMJRPD. CONCLUSIONS: The results of this investigation indicate that 10-weeks of an introductory judo course may increase CMJPP, however, has no effect on postural control or bilateral MVC strength of the DOM and NON hand during varied stance conditions. Furthermore, results reveal that bilateral MVC exertion has no influence on postural control performed during varied stance conditions.
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Date Issued: 2016
Identifier: CFE0006148, ucf:51157
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0006148

Title: The Reproducibility and Validity of Using the Dmax Method to Predict Physical Working Capacity at Fatigue Threshold.
Creator: Riffe, Joshua, Stout, Jeffrey, Hoffman, Jay, Fukuda, David, University of Central Florida
Abstract / Description: Although the original (ORG) physical working capacity at fatigue threshold (PWCFT) assessment has demonstrated strong reliability and sensitivity to training and/or nutritional interventions, limitations may exist regarding the method of PWCFT estimation. However, a relatively new mathematical method, called Dmax, has been shown to be objective and reliable when estimating metabolic and neuromuscular fatigue thresholds. To date, however, no study has examined whether the Dmax method for...
Show moreAlthough the original (ORG) physical working capacity at fatigue threshold (PWCFT) assessment has demonstrated strong reliability and sensitivity to training and/or nutritional interventions, limitations may exist regarding the method of PWCFT estimation. However, a relatively new mathematical method, called Dmax, has been shown to be objective and reliable when estimating metabolic and neuromuscular fatigue thresholds. To date, however, no study has examined whether the Dmax method for estimating the work rate at PWCFT is similar to the ORG method. PURPOSE: The purpose of this study is to evaluate the reliability and validity of the Dmax-EMG method for estimating and tracking changes in PWCFT. METHODS: In the reproducibility study, 11 men (age: 21.9 (&)#177; 1.37 years; height: 175.6 (&)#177; 8.65 cm; body mass: 82.1 (&)#177; 13.92 kg) completed two incremental exercise tests (GXT) to exhaustion on nonconsecutive days. In the validity study, 11 active men (age: 23.4 (&)#177; 3.0 years; height: 177.9 (&)#177; 7.8 cm; body mass: 80.9 (&)#177; 10.7 kg) and 10 active women (age: 22.3 (&)#177; 3.1 years; height: 166.6 (&)#177; 9.5 cm; body mass: 62.8 (&)#177; 8.7 kg) volunteered to perform 12 sessions of high-intensity interval training (HIIT) over 4-weeks along with a pre- and post-training GXT to compare the Dmax to the ORG method of estimating PWCFT. RESULTS: The reproducibility study revealed no significant differences between the first (181.5 (&)#177; 29.2 W) and second (181.9 (&)#177; 26.18 W) GXT trials (p = 0.87). In addition, ICC3,1 resulted in 0.949 with an SEM of 6.28 W and a MD of 17.41 W. In the cross-validation, the CE between actual and predicted PWCFT was not statistically different at pre (-6.7 W; p (>) 0.05) or post (-7.2 W; p (>) 0.05). Pre (r = 0.87) and post (r = 0.84) validity coefficients were considered very strong and the pre and post TE PWCFT values were 30.8 W and 32.5 W, respectively. Wide limits of agreement were calculated in the Bland-Altman analyses (pre: -68.36 to 54.93 W; post: -57.77 to 72.06 W) with no significant biases in both pre (-6.7 (&)#177; 30.8 W; p = 0.330) and post (-7.2 (&)#177; 32.5 W; p = 0.325). In addition, 95.2% and 100% participants fell within (&)#177;1.96 standard deviations of the mean difference for pre and post, respectively. CONCLUSION: Results of the study suggest that the Dmax method is both a reproducible and a valid method to estimate PWCFT when compared to the ORG method in young men.
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Date Issued: 2016
Identifier: CFE0006168, ucf:51155
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0006168

Title: The effects of four weeks of high intensity interval training and (&)#223;-hydroxy-(&)#223;-methylbutyric free acid on the onset of neuromuscular fatigue.
Creator: Miramonti, Amelia, Stout, Jeffrey, Hoffman, Jay, Fukuda, David, University of Central Florida
Abstract / Description: This study investigated the effects of high intensity interval training (HIIT) and ?-hydroxy-?-methylbutyric free acid (HMBFA) on the onset of neuromuscular fatigue in healthy young men and women. Thirty-seven subjects (22 men and 15 women; mean (&)#177; SD age = 22.8 (&)#177; 3.4yrs) completed an incremental cycle ergometer test (GXT) to exhaustion. During the GXT, electromyography (EMG) signals from the right vastus lateralis were recorded to determine the power output at the onset of...
Show moreThis study investigated the effects of high intensity interval training (HIIT) and ?-hydroxy-?-methylbutyric free acid (HMBFA) on the onset of neuromuscular fatigue in healthy young men and women. Thirty-seven subjects (22 men and 15 women; mean (&)#177; SD age = 22.8 (&)#177; 3.4yrs) completed an incremental cycle ergometer test (GXT) to exhaustion. During the GXT, electromyography (EMG) signals from the right vastus lateralis were recorded to determine the power output at the onset of neuromuscular fatigue (PWCFT), and peak wattage was used to assign individual training loads.After baseline testing (PRE), subjects were randomly assigned to one of three groups: control (C, n = 9), training with placebo (P, n = 14), or training with supplementation (S, n = 14). Subjects assigned to P and S completed 12 HIIT sessions over 4 weeks while subjects assigned to C were asked to maintain their normal diet and activity patterns. After 4 weeks, subjects returned for post-testing (POST). The PWCFT values (W) were determined using a DMAX method. The EMG amplitude root mean square ((&)#181;Vrms) values were used to generate a third-order polynomial regression (3PR) representing the increase in (&)#181;Vrms versus time of the GXT. The onset of fatigue (TF) was defined as the x-value (time, s) of the point on the 3PR that measured the maximal perpendicular distance from the line between the first and last data points. TF was used to estimate PWCFT according to the equation: PWCFT = PO + a ? (n/N), where PO is the power output of the stage in which TF occurred, a is the increment in power output between GXT stages (25W), n is the difference (s) between TF and the beginning of the stage during which TF occurred, and N is the duration of a stage (120s).A two-way repeated measures ANOVA was used to identify group (&)#215; time interaction for PWCFT. If a significant interaction occurred, one-way factorial ANOVAs were used. Fisher's least significant difference post hoc comparisons were performed between groups. If a significant main effect occurred, dependent samples t-tests with Bonferroni corrections (p = [0.05/3] = 0.017) were performed across time for each group.The two-way ANOVA resulted in a significant interaction (F = 6.69, p = 0.004). Follow-up analysis with one-way ANOVA resulted in no difference among groups at PRE (F = 0.87, p = 0.43), however a significant difference was shown for POST values (F = 5.46, p = 0.009). Post-hoc analysis among POST values showed significant differences between S and both P (p = 0.034) and C (p = 0.003). No differences (p = 0.226) were noted between P and C. Paired samples t-tests detected significant changes following HIIT for S (p (<) 0.001) and P (p = 0.016), but no change in C (p = 0.473).Results of this study indicate that HIIT was effective in delaying the onset of fatigue, but supplementation with HMBFA in conjunction with HIIT was more effective than HIIT alone. An increase in PWCFT represents an increase in the maximal power output an individual can sustain without eliciting fatigue. Therefore, HIIT can be used to improve performance in both endurance activities as well as intermittent sports. In addition, HMBFA supplementation is a simple method that can be used to maximize the benefits of HIIT.Acknowledgments: Metabolic Technologies, Inc. provided the supplement and funding for this study.
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Date Issued: 2015
Identifier: CFE0006043, ucf:50968
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0006043

Title: Mathematical Modeling of Heart Rate Deflection Point in Relation to Respiratory Compensation and Treadmill Running Performance.
Creator: Baker, Kayla, Fukuda, David, Hoffman, Jay, Stout, Jeffrey, University of Central Florida
Abstract / Description: Heart rate deflection point (HRDP), identified as the second breakpoint in the (")intensity / heart rate(") relationship, is indicative of the anaerobic threshold (AT). This point can be determined via bi-segmental linear regression (2SEG) or through use of the maximal distance model (D-max); however, the relationship between these methods has yet to be investigated 2. Purpose: To compare the use of 2SEG and D-max methods to determine HRDP and to examine the relationship between these values...
Show moreHeart rate deflection point (HRDP), identified as the second breakpoint in the (")intensity / heart rate(") relationship, is indicative of the anaerobic threshold (AT). This point can be determined via bi-segmental linear regression (2SEG) or through use of the maximal distance model (D-max); however, the relationship between these methods has yet to be investigated 2. Purpose: To compare the use of 2SEG and D-max methods to determine HRDP and to examine the relationship between these values with a metabolic threshold, respiratory compensation point (RCP), as well as running performance [5,000 meter treadmill time trial (5Ktime)]. Methods: Nineteen recreationally active men (n=9, 25.56(&)#177;3.17 y, 1.77(&)#177;0.05 m, 83.52(&)#177;6.77 kg, 48.98(&)#177;7.37 ml(&)#183;kg(&)#183;min-1) and women (n=10, 22.78(&)#177;2.11 y, 1.64(&)#177;0.07 m, 62.28(&)#177;6.20 kg, 42.32(&)#177;4.13 ml(&)#183;kg(&)#183;min-1) were recruited for this study. Participants completed two experimental trials, consisting of a graded exercise test to exhaustion (GXT) and 5,000m time trial on the treadmill. Estimates of HRDP and RCP were calculated from data collected during the GXT. One-way repeated measures analysis of variance was used to compare HRDP found through 2SEG (HRDP2SEG), HRDP found through D-max (HRDPD-max), and RCP. Pearson product moment correlations were used to examine the relationship between variables (HRDP2SEG, HRDPD-max, RCP, and 5Ktime). Results: No differences were found between HRDP2SEG (176.70(&)#177;9.40 bpm), HRDPD-max (178.18(&)#177;6.85 bpm), and RCP (176.92(&)#177;6.63 bpm) (p = 0.533). Strong correlations were found between HRDP2SEG and HRDPD-max (r = 0.831, p (<) 0.0001), RCP and HRDP2SEG (r = 0.650, p = 0.003), and RCP and HRDPD-max (r = 0.619, p = 0.005). No relationship was found between 5Ktime and HRDP2SEG (r = 0.419, p = 0.074), HRDPD-max (r = 0.241, p = 0.321), or RCP (r = 0.193, p = 0.429). Similar limits of agreement were found for all comparisons (HRDP2SEG and RCP, p = 0.070; HRDPD-max and RCP, p = 0.868; HRDP2SEG and HRDPD-max, p = 0.029), however, systematic bias was found between HRDP2SEG and HRDPD-max. Conclusion: Based on these results, HRDP2SEG and HRDPD-max could potentially be used interchangeably as methods to determine HRDP. However, the potential for systematic bias must be taken into consideration. Additionally, the results indicate that RCP and HRDP may provide similar estimates of the anaerobic threshold, but none of these thresholds appear to be related to 5Ktime on a treadmill.
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Date Issued: 2016
Identifier: CFE0006070, ucf:50944
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0006070

Title: Effects of an Acute High-Volume Isokinetic Intervention on Circulating Levels of TNF-? and STNFR: Influence of Age.
Creator: Arroyo Delgado, Eliott, Wells, Adam, Hoffman, Jay, Stout, Jeffrey, Fukuda, David, University of Central Florida
Abstract / Description: The immune system has been implicated in recovery and muscle regeneration following exercise. In response to muscle damage, the immune system responds with an increase in circulating pro-inflammatory cytokines with the goal of recruiting leukocytes to the damaged area. Tumor Necrosis Factor-alpha (TNF-?), in particular, has been shown to be implicated in both muscle regeneration and muscle wasting. However, it remains unclear whether TNF-? is responsible for the age-related losses in muscle...
Show moreThe immune system has been implicated in recovery and muscle regeneration following exercise. In response to muscle damage, the immune system responds with an increase in circulating pro-inflammatory cytokines with the goal of recruiting leukocytes to the damaged area. Tumor Necrosis Factor-alpha (TNF-?), in particular, has been shown to be implicated in both muscle regeneration and muscle wasting. However, it remains unclear whether TNF-? is responsible for the age-related losses in muscle size and function. Also, due to the high clearance rate of TNF-? from circulation, analyzing the circulating levels of soluble TNF-? receptors 1 and 2 (STNFR1 and STNFR2) may provide a better indication of inflammatory events. Therefore, the purpose of this study was to compare changes in circulating levels of TNF-?, STNFR1, and STNFR2 following an acute muscle damaging intervention in young age (YA) and middle-aged (MA) males. Recreationally active young (YA; N=9, 21.8 (&)#177; 2.2 y, 179.5 (&)#177; 4.9 cm, 91.2 (&)#177; 12.2 kg, 21.8 (&)#177; 4.3% BF) and middle-aged (MA; N=10, 47.0 (&)#177; 4.4 y, 176.8 (&)#177; 7.6 cm; 96.0 (&)#177; 21.5 kg, 25.4 (&)#177; 5.3% BF) males completed an acute muscle damaging protocol (MDP). Blood samples were obtained at baseline (BL), immediately (IP), 30 minutes (30P), 60 minutes (60P), 120 minutes (120P), 24 hours (24H), and 48 hours (48H) post-MDP. Lower body performance was analyzed via isokinetic dynamometer at BL, IP, 120P, 24H, and 48H. No significant group x time interactions or main group effects were observed for TNF-?, STNFR1, STNFR2 or any marker of muscle damage. When collapsed across groups, plasma lactate was significantly elevated at IP (p (<) 0.001) and 30P (p = 0.003); serum myoglobin was increased at 30P (p = 0.002), 60P (p = 0.001), and 120P (p = 0.007); creatine kinase was elevated at 24H (p = 0.001) and 48H (p = 0.005). Plasma concentrations of TNF-? were unchanged following MDP. With both groups combined, serum STNFR1 was decreased at 30P (p = 0.001) and increased at 48H (p = 0.028). Serum STNFR2 was decreased at 30P (p = 0.008), 60P (p = 0.003), and 120P (p = 0.002). The results of this study indicate that the TNF-? and STNFRs response to exercise is similar between young and middle-aged males. Measuring STNFRs may be a more appropriate method of assessing the acute inflammatory response to muscle damage. In addition, an acute bout of exercise may attenuate ectodomain shedding of TNFR1 and TNFR2.
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Date Issued: 2017
Identifier: CFE0006561, ucf:51350
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0006561

Title: Role of brain derived neurotrophic factor (BDNF) in stimulating strength improvements induced by short-term resistance training.
Creator: Church, David, Hoffman, Jay, Stout, Jeffrey, Fukuda, David, Stock, Matt, University of Central Florida
Abstract / Description: Strength adaptations from short-term resistance training are thought to be related primarily to neurological adaptations. Considering brain-derived neurotrophic factor (BDNF) role in the nervous system, it is possible that BDNF has a role in these adaptations. Fourteen untrained males were randomized into either a resistance training (RT; n =8) or control (CON; n=6) group. Motor unit (MU) recruitment at 50% and 80% of each participant's maximal voluntary isometric contraction (MVIC), muscle...
Show moreStrength adaptations from short-term resistance training are thought to be related primarily to neurological adaptations. Considering brain-derived neurotrophic factor (BDNF) role in the nervous system, it is possible that BDNF has a role in these adaptations. Fourteen untrained males were randomized into either a resistance training (RT; n =8) or control (CON; n=6) group. Motor unit (MU) recruitment at 50% and 80% of each participant's maximal voluntary isometric contraction (MVIC), muscle cross sectional area (CSA) and thickness (MT), as well as one-repetition maximum (1RM) of the squat (SQT), leg press (LP), and leg extension (LE) were performed before (PRE) and after (POST) the training period. Following the MU assessment, the recruitment threshold (RT; % MVIC) and mean firing rate (MFR; pulse per second [pps]) of each MU were determined. Linear regression was used to quantify the slope (pps/% MVIC) and y-intercept (pps) of the MFR versus RT relationship for each participant and time point. Participants completed an acute resistance exercise bout at PRE and POST consisting of 3 sets of 8 (-) 10 repetitions with 90 seconds of rest between each set of SQT, LP, and LE. Blood samples were obtained following a 4-hour fast before (BL), immediately-(IP), and one-(1H) hour post resistance exercise. RT subjects performed the same resistance exercise protocol at PRE twice a week for 3-weeks. CON subjects were instructed to not perform any resistance exercise. Area under the curve (AUC) analysis was determined by the trapezoidal method. Pearson product-moment correlations were used to examine selected bivariate relationships. The ?BDNF AUC was significantly correlated to the relative 80% ?y-intercept (r=-0.626, p=0.030), and trended to be correlated to the relative 80% ?slope (r=0.551, p=0.063). Our results indicate that ? in plasma BDNF concentrations appear to be related to ?'s MU recruitment at high intensities (80% of MVIC) of exercise.
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Date Issued: 2018
Identifier: CFE0006988, ucf:51665
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0006988

Title: The Effects of Sprint Interval Training and Maturity Status on Metabolic and Neuromuscular Fatigue Thresholds in Adolescents.
Creator: Beyer, Kyle, Fukuda, David, Hoffman, Jay, Stout, Jeffrey, Fragala, Maren, University of Central Florida
Abstract / Description: Purpose: To examine the maturity-related differences in the adaptations to systemic and localized fatigue thresholds (FTs) in response to sprint interval training (SIT) amongst adolescent male athletes. Methods: Twenty-seven adolescent male athletes, 11-17 years of age, completed pre-testing, six weeks of SIT, and post-testing. Participants were grouped according to their number of years from peak height velocity (PHV), an estimation of somatic maturity status, into PRE (()+1.5yr) PHV groups....
Show morePurpose: To examine the maturity-related differences in the adaptations to systemic and localized fatigue thresholds (FTs) in response to sprint interval training (SIT) amongst adolescent male athletes. Methods: Twenty-seven adolescent male athletes, 11-17 years of age, completed pre-testing, six weeks of SIT, and post-testing. Participants were grouped according to their number of years from peak height velocity (PHV), an estimation of somatic maturity status, into PRE ((<)-1.5yr), PERI (between -1.5 to +1.5yr) and POST ((>)+1.5yr) PHV groups. Each testing session consisted of a ramp exercise protocol on a cycle ergometer. During the protocol, three systemic FTs, gas exchange threshold, ventilatory threshold, and respiratory compensation point were calculated from gas exchange and ventilatory parameters. Also, three localized FTs, neuromuscular fatigue threshold (NFT), deoxyhemoglobin breakpoint (HHbBP), and oxygenation deflection point (OxDP) were calculated from electromyography (NFT) and near-infrared spectroscopy signals (HHbBP and OxDP) from the vastus lateralis of both legs. Data were plotted versus oxygen consumption and 30-second moving averages were calculated. All FTs were determined using the maximal distance method. Localized FTs were averaged between the two legs. The six weeks of SIT consisted of repeated 20-second (")all-out(") sprints on a cycle ergometer against a load equivalent to 7.5% of body mass with 4-minute rest periods. Maturity-related differences to the adaptations to SIT were assessed with mixed-factorial ANOVA and magnitude-based inferences. Results: During training, POST and PERI completed significantly greater relative work (p=0.003 and p=0.002, respectfully) and peak power (p=0.025 and p=0.023, respectfully) per session than PRE. Furthermore, POST achieved significantly greater peak rotations per minute than PRE (p=0.001) and PERI (p=0.042) during the first training session. No significant group(&)#215;time interactions existed for absolute V?O2max (p=0.386), relative V?O2max (p=0.341) or maximum workload (p=0.593). However, there was a significant group(&)#215;time interaction (p=0.030) for FTs, with POST having significantly greater changes than PRE (p=0.026) and PERI (p=0.023), and was the only group to experience a significant improvement in FTs from training (p(<)0.001). In addition, magnitude based inferences revealed that POST had Likely improvements in all measures of maximal aerobic performance, while PERI only had Likely improvements in maximum workload and PRE experienced Trivial changes. Furthermore, all measured FTs experienced Likely or Very Likely improvements amongst POST; however, PRE and PERI only had improvements in NFT and HHbBP. Conclusion: SIT improved maximal aerobic performance and FTs in POST, but had limited affects in PRE and PERI. The maturity-related differences in the adaptations to SIT may be due to the differences in performance during the training program or underlying physiological changes that occur with maturation.
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Date Issued: 2017
Identifier: CFE0006934, ucf:51644
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0006934

Title: Intramuscular TNF-alpha signaling in response to resistance exercise and recovery in untrained males.
Creator: Townsend, Jeremy, Stout, Jeffrey, Hoffman, Jay, Fukuda, David, Roberts, Michael, University of Central Florida
Abstract / Description: INTRODUCTION: The nuclear factor kappa B (NF-??) signaling cascade is responsible for mediating stress-activated catabolic effects of Tumor Necrosis Factor Alpha (TNF-?) downstream of the TNF receptor (TNFR1). NF-?? transcription factor remains inhibited in the cytosol of the muscle and can be stimulated for translocation and transcription by a variety of external stimuli, most notably by pro-inflammatory cytokines and oxidative stress. Nevertheless, currently there is a gap in the literature...
Show moreINTRODUCTION: The nuclear factor kappa B (NF-??) signaling cascade is responsible for mediating stress-activated catabolic effects of Tumor Necrosis Factor Alpha (TNF-?) downstream of the TNF receptor (TNFR1). NF-?? transcription factor remains inhibited in the cytosol of the muscle and can be stimulated for translocation and transcription by a variety of external stimuli, most notably by pro-inflammatory cytokines and oxidative stress. Nevertheless, currently there is a gap in the literature with regard to the time course effect of NF-?? signaling following acute resistance exercise in humans. PURPOSE: To observe the effects of an acute lower-body resistance exercise protocol and subsequent recovery on intramuscular NF- ?? signaling. METHODS: Twenty-eight untrained males were assigned to either a control (CON; n=11) or exercise group (EX; n=17) and completed a lower-body resistance exercise protocol consisting of the back squat, leg press, and leg extension exercises. Skeletal muscle microbiopsies were obtained from the vastus lateralis pre-exercise (PRE), 1-hour (1HR), 5-hour (5HR), and 48-hours (48HR) post-resistance exercise. Multiplex signaling assay kits (EMD Millipore, Billerica, MA, USA) were used to quantify the total protein (TNFR1, c-Myc) or phosphorylation status of proteins (IKKa/b, NF- ??, IkB) specific to apoptotic signaling pathways using MAGPIX(&)#174; (Luminex, Austin, TX, USA). Repeated measures ANOVA analysis was used to determine the effects of the exercise bout on intramuscular signaling at each timepoint. Additionally, change scores were analyzed by magnitude based inferences to determine a mechanistic interpretation. RESULTS: Repeated measures ANOVA indicated a trend for a two way interaction between the EX and CON Group (p=0.064). Magnitude based inferences revealed a (")Very Likely(") increase in total c-Myc from PRE-5H and a (")Likely(") increase in IkB phosphorylation from PRE-5H. CONCLUSION: Results indicate that c-Myc transcription factor and phosphorylation of IkB are elevated following acute intense resistance exercise in untrained males. These data suggest that NF- ?? signaling plays a role in ribosome biogenesis and skeletal muscle regeneration following resistance exercise in young untrained males.
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Date Issued: 2016
Identifier: CFE0006191, ucf:51089
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0006191

Title: Physiological Muscle Qualitative Changes in Response to Resistance Training in Older Adults.
Creator: Scanlon, Tyler, Fragala, Maren, Hoffman, Jay, Stout, Jeffrey, University of Central Florida
Abstract / Description: Muscle function is determined by structure and morphology at the architectural level. In response to resistance training, older adults have demonstrated that the neuromuscular system has a substantial adaptability, which may compensate for muscle size and quality and lead to improved functional capacities and higher quality of life. PURPOSE: The purpose of this study was to examine the effect of six weeks of progressive resistance exercise on muscle morphology and architecture in healthy...
Show moreMuscle function is determined by structure and morphology at the architectural level. In response to resistance training, older adults have demonstrated that the neuromuscular system has a substantial adaptability, which may compensate for muscle size and quality and lead to improved functional capacities and higher quality of life. PURPOSE: The purpose of this study was to examine the effect of six weeks of progressive resistance exercise on muscle morphology and architecture in healthy older adults. METHODS: Twenty- five healthy men and women were randomly assigned to either six weeks of progressive resistance training (RT) (n=13; age = 71.08 (&)#177; 6.75, BMI = 28.5 (&)#177; 5.22) or to serve as a control (CON) (n = 12; age = 70.17 (&)#177; 5.58, BMI = 27.52 (&)#177; 5.6). Fat mass (FM), lean mass (LM), and lean thigh mass (LTM) were evaluated using dual x-ray absorptiometry. Lower body strength was estimated by predicting maximal knee extensor strength (1RM). Muscle quality (MQ) was evaluated as strength per unit mass (kg/kg). Cross-sectional area (CSA), muscle thickness (MT), fascicle length (Lf), pennation angle (cos?), and echo intensity (EI) of the rectus femoris (RF) and vastus lateralis (VL) were collected using B-mode ultrasound and extended field of view (FOV) ultrasound. EI was quantified using grayscale analysis software. Strength per unit of echo intensity (REI) was determined by dividing 1RM by EI of the thigh. Physiological cross-sectional area (PCSA) was calculated as the ratio of (CSA x cos?) / (EI x Lf). A 2x2 (group [exercise vs. control] x time [pre vs. post]) repeated measures ANOVA was used to identify group differences and group x time interactions and stepwise regression was performed to assess variables related to strength. RESULTS: 1RM increased by 31.9% (p ? 0.01) in the RT group and was significantly correlated to PCSA of the thigh (r = .579; p = .003) at baseline. MQ increased 31.4% (p ? 0.01) in the RT group consistent with an REI increase of 33.3% (p ? 0.01). There were no significant changes in LTM in either group. VL CSA increased 7.4%, (p ? 0.05) and demonstrated a significant interaction (p ? 0.05) in the RT group. There were no significant changes in the CON group for 1RM, MQ, REI or VL CSA. PCSA demonstrated a significant (p ? 0.05) group x time interaction but did not significantly change in either group. EI did not significantly change in the RT or CON groups. CONCLUSION: Calculated PCSA of the thigh assessed by ultrasound was related to the force producing capacity of muscle and demonstrated a significant interaction following resistance training. Short term resistance exercise training was effective in increasing 1RM, muscle quality as relative strength, muscle quality as relative echo intensity, and muscle morphology, but not EI. In addition, ultrasonography appears to be a safe, feasible, informative and sensitive clinical technique to aid in our understanding of muscle strength, function, and quality.
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Date Issued: 2013
Identifier: CFE0004748, ucf:49782
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0004748

Title: National Collegiate Athletic Association Strength and Conditioning Coaches' Knowledge and Practices Regarding Prevention and Recognition of Exertional Heat Stroke.
Creator: Valdes, Anna, Hoffman, Jay, Boote, David, Fisher, Thomas, Mitchell, Debby, University of Central Florida
Abstract / Description: The purpose of this study was to assess and determine the current level of knowledge that National Collegiate Athletic Association (NCAA) Strength and Conditioning Coaches (SCCs) possess regarding exertional heat stroke (EHS) prevention and recognition and to determine if SCC certification type had any effect. Major findings of this study support the view that SCCs need more preparation, education and training to increase their competency in preventing and recognizing EHS. Research found that...
Show moreThe purpose of this study was to assess and determine the current level of knowledge that National Collegiate Athletic Association (NCAA) Strength and Conditioning Coaches (SCCs) possess regarding exertional heat stroke (EHS) prevention and recognition and to determine if SCC certification type had any effect. Major findings of this study support the view that SCCs need more preparation, education and training to increase their competency in preventing and recognizing EHS. Research found that there was no significant difference in scores on the EHS scale based on SCC certification (CSCS vs. SCCC) after accounting for experience, education or division but the CSCS certified professionals scored higher on all the factors as compared to SCCs without the CSCS.. The major key finding was that SCCs lacked essential knowledge to prevent or recognize EHS. Furthermore, the study defines relevant EHS prevention and recognition competencies that an undergraduate curriculum, graduate curriculum and professional certification providers, should include and emphasize in their preparation programs.
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Date Issued: 2013
Identifier: CFE0004766, ucf:49790
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0004766

Title: The effect of training volume and intensity on improvements in muscular strength and size in resistance-trained men.
Creator: Mangine, Gerald, Hoffman, Jay, Fukuda, David, Stout, Jeffrey, Ratamess, Nicholas, University of Central Florida
Abstract / Description: The magnitude of improvements in muscular strength and size are influenced by the volume and intensity of a resistance training program. While it is clearly advantageous for resistance-trained individuals to utilize programming specific to these goals, it not clear which is more important. Therefore the purpose of the present investigation was to determine the effect of focusing on training volume versus intensity on changes in muscle size and strength. Changes in muscular strength and size...
Show moreThe magnitude of improvements in muscular strength and size are influenced by the volume and intensity of a resistance training program. While it is clearly advantageous for resistance-trained individuals to utilize programming specific to these goals, it not clear which is more important. Therefore the purpose of the present investigation was to determine the effect of focusing on training volume versus intensity on changes in muscle size and strength. Changes in muscular strength and size were examined in 29 resistance-trained men following 8 weeks of resistance training. Participants were randomly assigned to either a high volume (VOL, n = 14, 4 x 10 (-) 12RM, 1min rest) or high intensity (INT, n = 15, 4 x 3 (-) 5RM, 3min rest) resistance training program. Lean body mass, lean arm and leg mass, were assessed by dual energy X-ray absorptiometry, while ultrasound images (VL-vastus lateralis, RF-rectus femoris, PM-pectoralis major, and TB-triceps brachii) were used to assess changes in muscle cross-sectional area (CSA) and thickness (MT). Strength was measured by one repetition-maximum (1RM) squat (SQ) and bench press (BP). Changes in muscular (RF (&) VL) activation in response to increases in submaximal SQ intensity (40-, 60-, 80-, (&) 100%-1RM) were assessed via surface electromyography. Blood samples were collected at baseline, immediately post, 30min post, and 60min post-exercise at week 3 (WK3) and week 10 (WK10), to assess plasma/serum testosterone, growth hormone (GH), insulin-like growth factor-1 (IGF1), cortisol (CORT), and insulin. Area under the curve analysis revealed a greater (p (<) 0.05) increase for VOL (WK3: GH (&) CORT; WK10: CORT) compared to INT. Compared to WK3, WK10 showed reduced responses for VOL (GH and CORT) and INT (IGF1). Significant group differences were observed for changes in lean arm mass (INT: 5.2 (&)#177; 2.9%, VOL: 2.2 (&)#177; 5.6%) and BP 1RM (INT: 14.8 (&)#177; 9.7%, VOL: 6.9 (&)#177; 9.0%). Over the course of 8 weeks, our data indicate that trained men would benefit more when focusing on training intensity, rather than volume, for strength and size improvements.
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Date Issued: 2015
Identifier: CFE0005658, ucf:50179
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0005658

Title: Determination of Critical Rest Interval using Repeated Sprint Ability Testing.
Creator: Lamonica, Michael, Fukuda, David, Hoffman, Jay, Stout, Jeffrey, Fragala, Maren, University of Central Florida
Abstract / Description: The critical power (CP) concept has been used to determine the appropriate rest interval during intermittent exercise through the investigation of critical rest interval (CRI). Repeated sprint ability (RSA) testing has been developed to define the athlete's ability to recover and maintain maximal effort during successive bouts. The CP model has been used to understand the physiological responses involved with intermittent exercise delineating between severe and heavy exercise intensity...
Show moreThe critical power (CP) concept has been used to determine the appropriate rest interval during intermittent exercise through the investigation of critical rest interval (CRI). Repeated sprint ability (RSA) testing has been developed to define the athlete's ability to recover and maintain maximal effort during successive bouts. The CP model has been used to understand the physiological responses involved with intermittent exercise delineating between severe and heavy exercise intensity domains. The primary purpose of this study was to determine the CRI from the work-time relationship given by RSA testing using varying work to rest ratios. The secondary purpose was to determine the validity of CRI by evaluation of physiological responses above and below estimated rest interval values during intermittent cycling.Twelve recreationally trained males (mean (&)#177; SD; age 24.1 (&)#177; 3.6yr; height 175.8 (&)#177; 7.0cm; weight 77.6 (&)#177; 12.8kg; V?O2peak 43.3 (&)#177; 5.6ml/kg/min; Body Fat (%) 24.5 (&)#177; 4.4) were recruited for this study. Participants performed a graded exercise test to determine V?O2peak and peak heart rate. Eight participants completed the same three RSA protocols with 6s maximal sprints and varying rest intervals (12-24s) on a cycle ergometer. Intermittent critical power (ICP) was calculated through the linear total work (TW) and time-to-exhaustion (TTE) relationship, whereas CRI was estimated using the average work per sprint and ICP. Seven subjects completed trials above and below estimated CRI to evaluate the validity of this estimate through the examination of the physiological responses. Breath-by-breath oxygen consumption (V?O2) and heart rate (HR) values were recorded during the validation trials. One-way repeated measures analysis of variance (ANOVA) was used to analyze the variables from the RSA trials. Paired samples t-tests were performed to compare performance and physiological variables above or below CRI during the validation trials. Two-way repeated measures ANOVA was used to examined the changes in oxygen consumption (V?O2), HR, mean power (MP), and TW throughout the validation trials. Significant differences (p (<) 0.1) were found for the number of intervals completed, TTE, average work per sprint, peak and mean V?O2 between RSA protocols. Linearity between TW and TTE was r2 = 0.952 (&)#177; 0.081. During the validation trials, TTE was significantly greater in the above versus the below CRI trial (2270.43 (&)#177; 941.15s vs. 1511.00 (&)#177; 811.0s). Furthermore, blood lactate concentration (8.94 (&)#177; 4.89mmol/L vs. 6.56 (&)#177; 3.45mmol/L), AveV?O2 (2.05 (&)#177; 0.36L/min vs. 1.78 (&)#177; 0.26L/min), V?O2peak (2.84 (&)#177; 0.48L/min vs. 2.61 (&)#177; 0.43L/min), and AveHR (151.14 (&)#177; 18.46bpm vs. 138.14 (&)#177; 17.51L/min) were significantly greater in the below CRI trial when compared to the above CRI trial. Significant interactions were found between above and below trials within minimal V?O2 response (F = 6.886, p = 0.024, ?2 = 0.534) to the recovery intervals and maximal HR (F = 4.51, p = 0.016, ?2 = 0.429) response to the work intervals. During the above CRI trial, minimal V?O2 response decreased over time (51-43%V?O2 peak) while maximal HR response achieved a steady state level (81-84%HRpeak). Conversely, minimal V?O2 response during the below CRI trial achieved a steady state level (54-58%V?O2 peak), whereas maximal HR response increased over time (84-90%HRpeak).The relationship between TW and TTE is appropriate for use with RSA testing with varying rest intervals. The differing physiological response during the validation trials may reflect changes in energy system contribution. In conclusion, CRI distinguished between physiological responses related to exercise intensity domains in a manner similar to CP estimates determined from other testing and exercise modalities.
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Date Issued: 2014
Identifier: CFE0005645, ucf:50168
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0005645

Title: Intramuscular anabolic signaling and endocrine response following different resistance exercise protocols in trained men.
Creator: Gonzalez, Adam, Hoffman, Jay, Stout, Jeffrey, Fukuda, David, Willoughby, Darryn, University of Central Florida
Abstract / Description: The mammalian/mechanistic target of rapamycin complex 1 (mTORC1) signaling pathway appears to be the primary regulator of protein synthesis and growth. While resistance exercise paradigms are often divided into hypertrophy (HYP) and strength (STR) protocols, it is unknown whether these protocols differentially stimulate mTORC1 signaling. The purpose of this study was to examine mTORC1 signaling in conjunction with circulating hormone concentrations following a typical lower-body HYP and STR...
Show moreThe mammalian/mechanistic target of rapamycin complex 1 (mTORC1) signaling pathway appears to be the primary regulator of protein synthesis and growth. While resistance exercise paradigms are often divided into hypertrophy (HYP) and strength (STR) protocols, it is unknown whether these protocols differentially stimulate mTORC1 signaling. The purpose of this study was to examine mTORC1 signaling in conjunction with circulating hormone concentrations following a typical lower-body HYP and STR resistance exercise protocol. Ten resistance-trained men (24.7(&)#177;3.4y; 90.1(&)#177;11.3kg; 176.0(&)#177;4.9cm) performed each resistance exercise protocol in a random, counterbalanced order. Blood samples were obtained at baseline (BL), immediately (IP), 30 minutes (30P), 1 hour (1H), 2 hours (2H), and 5 hours (5H) post-exercise. Fine needle muscle biopsies were completed at BL, 1H, and 5H. Electromyography of the vastus lateralis was also recorded during each protocol. HYP and STR produced a similar magnitude of muscle activation across sets. Myoglobin and lactate dehydrogenase concentrations were significantly greater following STR compared to HYP (p=0.01-0.02), whereas the lactate response was significantly higher following HYP compared to STR (p=0.003). The GH, cortisol, and insulin responses were significantly greater following HYP compared to STR (p=0.0001-0.04). No significant differences between protocols were observed for the IGF-1 or testosterone response. Intramuscular anabolic signaling analysis revealed a significantly greater (p=0.03) phosphorylation of IGF-1 receptor at 1H following HYP compared to STR. Phosphorylation status of all other signaling proteins including mTOR (mammalian target of rapamycin), p70S6k (ribosomal S6 kinase 1), and RPS6 (ribosomal protein S6) were not significantly different between trials. Despite significant differences in markers of muscle damage and the endocrine response following STR and HYP, both protocols appeared to elicit similar mTORC1 activation in resistance-trained men.
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Date Issued: 2015
Identifier: CFE0005621, ucf:50203
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0005621

Title: Phosphatidic Acid Increases Lean Body Tissue and Strength In Resistance Trained Men.
Creator: Williams, David, Hoffman, Jay, Fragala, Maren, Stout, Jeffrey, University of Central Florida
Abstract / Description: ABSTRACTPhosphatidic Acid (PA) is a natural phospholipid compound derived from lecithin which is commonly found in egg yolk, grains, fish, soybeans, peanuts and yeast. It has been suggested that PA is involved in several intracellular processes associated with muscle hypertrophy. Specifically, PA has been reported to activate protein synthesis through the mammalian target of rapamycin (mTOR) signaling pathway and thereby may enhance the anabolic effects of resistance training. To our...
Show moreABSTRACTPhosphatidic Acid (PA) is a natural phospholipid compound derived from lecithin which is commonly found in egg yolk, grains, fish, soybeans, peanuts and yeast. It has been suggested that PA is involved in several intracellular processes associated with muscle hypertrophy. Specifically, PA has been reported to activate protein synthesis through the mammalian target of rapamycin (mTOR) signaling pathway and thereby may enhance the anabolic effects of resistance training. To our knowledge, no one has examined the effect of PA supplementation in humans while undergoing a progressive resistance training program. To examine the effect of PA supplementation on lean soft tissue mass (LM) and strength after 8 weeks of resistance training.Fourteen resistance-trained men (mean (&)#177; SD; age 22.7 (&)#177; 3.3 yrs; height: 1.78 (&)#177; 0.10m; weight: 89.3 (&)#177; 16.3 kg) volunteered to participate in this randomized, double-blind, placebo-controlled, repeated measures study. The participants were assigned to a PA group (750mg/day; Mediator(&)#174;, ChemiNutra, MN, n=7) or placebo group (PL; rice flower; n=7), delivered in capsule form that was identical in size, shape and color. Participants were tested for 1RM strength in the bench press (BP) and squat (SQ) exercise. LM was measured using dual-energy X-ray absorptiometry. After base line testing, the participants began supplementing PA or PLfor 8 weeks during a progressive resistance training program intended for muscular hypertrophy. Data was analyzed using magnitude-based inferences on mean changes for BP, SQ and LM. Furthermore, the magnitudes of the inter-relationships between changes in total training volume and LM were interpreted using Pearson correlation coefficients, which had uncertainty (90% confidence limits) of approximately +0.25.In the PA group, the relationship between changes in training volume and LM was large(r=0.69, +0.27; 90%CL), however, in the PL group the relationship was small (r=0.21, +0.44; 90%CL). PA supplementation was determined to be likely beneficial at improving SQ and LM over PL by 26% and 64%, respectively. The strong relationship between changes in total training volume and LM in the PA group suggest that greater training volume most likely lead to the greater changes in LM, however, no such relationship was found with PL group. For the BP data, the PA group resulted in a 42% greater increase in strength over PL, although the effect was considered unclear. While more research is needed to elucidate mechanism of action; the current findings suggest that in experienced resistance trained men supplementing 750mg PA per day for 8 weeks may likely benefit greater changes in muscle mass and strength compared with resistance training only. ?
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Date Issued: 2012
Identifier: CFE0004641, ucf:49897
Format: Document (PDF)
PURL: http://purl.flvc.org/ucf/fd/CFE0004641

Electromyography (5)	+ -
Inflammation (4)	+ -
Resistance Training (3)	+ -
Aging (2)	+ -
Exercise Physiology (2)	+ -

Muscle Damage (2)	+ -
Neuromuscular Fatigue (2)	+ -
Resistance Exercise (2)	+ -
fatigue threshold (2)	+ -
repeated sprint ability (2)	+ -
running performance (2)	+ -
ultrasound (2)	+ -
5000m running (1)	+ -
5k running (1)	+ -
?-Hydroxy-?-Methylbutyrate (1)	+ -
Adhesion (1)	+ -
Aerobic (1)	+ -
Alanine-Glutamine (1)	+ -
Altitude (1)	+ -
Analytical Chemistry (1)	+ -
BDNF (1)	+ -
C-C Chemokine Receptor 2 (1)	+ -
CD11b (1)	+ -
CSCS (1)	+ -
Caffeine (1)	+ -
Center of pressure (1)	+ -
Chemokines (1)	+ -
Chemotaxis (1)	+ -
Cognition (1)	+ -
Cognitive Function (1)	+ -

Hoffman, Jay (32)	+ -
University of Central Florida (32)	+ -
Stout, Jeffrey (30)	+ -
Fukuda, David (24)	+ -
Fragala, Maren (15)	+ -

Wells, Adam (4)	+ -
Beyer, Kyle (2)	+ -
Boone, Carleigh (2)	+ -
Lamonica, Michael (2)	+ -
Arroyo Delgado, Eliott (1)	+ -
Baker, Kayla (1)	+ -
Belfield, Kevin (1)	+ -
Bohner, Jonathan (1)	+ -
Boote, David (1)	+ -
Campiglia, Andres (1)	+ -
Church, David (1)	+ -
Emerson, Nadia (1)	+ -
Ferguson, Matthew (1)	+ -
Fisher, Thomas (1)	+ -
Girts, Ryan (1)	+ -
Gonzalez, Adam (1)	+ -
Gordon, Joseph (1)	+ -
Harper, James (1)	+ -
Jajtner, Adam (1)	+ -
Kang, Jie (1)	+ -
Mangine, Gerald (1)	+ -
McCormack, William (1)	+ -
Miramonti, Amelia (1)	+ -
Mitchell, Debby (1)	+ -
Muddle, Tyler (1)	+ -

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