Influence of Body Composition, Load-Velocity Profiles, and Sex-Related Differences on Army Combat Fitness Test Performance

ABSTRACT

Boffey, D, DiPrima, JA, Kendall, KL, Hill, EC, Stout, JR, and Fukuda, DH. Influence of body composition, load-velocity profiles, and sex-related differences on army combat fitness test performance. J Strength Cond Res 37(12): 2467-2476, 2023-The Army Combat Fitness Test (ACFT) became the U.S. Army's mandatory physical fitness test in April of 2022. The purpose of this study was to determine the relationship between ACFT performance and both body composition and velocity profiles and to determine sex differences for these variables. Data were collected at 2 timepoints 4 months apart, from male (n = 55) and female (n = 17) Army Reserve Officers' Training Corps (ROTC) cadets. Body composition was assessed with a bioelectrical impedance spectroscopy device, and cadets completed a hex bar deadlift load-velocity profile (LVP) and ACFT on separate days. Stepwise multiple regressions were used to explain the amount of variance in ACFT total score and individual event performance. Significance for statistical tests was defined as an alpha level of p ≤ 0.05. Muscle mass and body fat percentage accounted for 49% of shared variance of total ACFT score, and deadlift maximal power and maximal velocity accounted for 67% of shared variance of total ACFT score. The 3 repetition maximum deadlift, standing power throw, hand-release push-up, and sprint-drag-carry events favored cadets with more muscle mass, whereas the leg tuck was influenced by the body fat percentage and the 2-mile run was affected by fat mass. Sex had greater predictive capability for the 2-mile run than body composition. Men outperformed women on all individual events, with the greatest differences on standing power throw and sprint-drag-carry. It is recommended that Army ROTC cadets taking the ACFT maximize lower-body power production and increase muscle mass.

Hybrid delivery of cluster-set resistance training for individuals previously treated for lung cancer: the results of a single-arm feasibility trial

BACKGROUND

Individuals with non-small cell lung cancer (NSCLC) are burdened by long-lasting symptoms (e.g., dyspnea and fatigue) post-treatment. These symptoms often reduce physical activity levels and increase the risk of functional decline. Though we have previously proposed cluster-set resistance training to mitigate symptom burden in lung cancer, there is currently no data on the feasibility or acceptability of this mode of exercise in cancer. Therefore, the purpose of this study was to investigate the feasibility and acceptability of a hybrid-delivery home-based cluster-set resistance training program in individuals with NSCLC stages I-III (i.e., early stage).

METHODS

This study aimed to recruit individuals with NSCLC stages I-III post-treatment to participate in 8 weeks of home-based resistance training, 3 days per week. The program included supervised sessions in the participants' homes and virtual supervision via videoconferencing. The primary outcome measure of feasibility was evaluated through recruitment, retention, and intervention fidelity (i.e., proportion of exercise completed, relative to what was prescribed). Intervention acceptability (i.e., ease and quality of virtual delivery, level of difficulty, and home-based approach) was assessed using a 4-point Likert-type scale from "strongly disagree" to "strongly agree".

RESULTS

Fourteen participants were recruited over a 6-month period, with 11 completing the intervention (2 withdrew due to unrelated illness, 1 withdrew due to requiring active treatment), yielding a retention rate of 79%. Characteristics of the participants who completed the intervention (n = 11) were as follows: mean age: 71 ± 10 years, mean BMI: 29.1 ± 6.5, and average time since diagnosis was 62 ± 51 months. Of completers, 27% were male, and 36% were Black; 10 were stage I (91%), and one was stage II (9%). Mean session attendance was 86.4 ± 9.5%. Mean intervention fidelity was 83.1 ± 13.1%. With regard to acceptability,  > 90% of participants positively rated all aspects of the intervention delivery. No adverse events related to exercise were recorded.

CONCLUSIONS

The hybrid delivery of a home-based resistance exercise program for individuals previously treated for early-stage NSCLC was found to be safe and feasible. Adaptations to the program for future interventions are required, particularly surrounding resistance exercise programming, and intervention delivery with home visits.

TRIAL REGISTRATION

ClinicalTrials.gov: NCT05014035 . Registered January 20, 2021.

Effect of 3 Different Set Configurations on Kinematic Variables and Internal Loads During a Power Snatch Session

ABSTRACT

Nagatani, T, Kendall, KL, Guppy, SN, Poon, WCK, and Haff, GG. Effect of 3 different set configurations on kinematic variables and internal loads during a power snatch session. J Strength Cond Res 37(10): 1929-1938, 2023-The aim of this study was to investigate the effect of 3 different set configurations on kinematic variables and internal loads during multiple sets performed with the power snatch. Ten strength-power athletes with at least 6 months of training experience performing the power snatch participated in this study, which consisted of 3 experimental protocols performed in a randomized repeated-measures design. The 3 protocols involved performing the power snatch for 3 sets of 5 repetitions at an average load of 75% 1 repetition maximum with a traditional (TRAD), cluster (CLU), or ascending cluster (A-CLU) protocol, where the training load was progressively increased across the set. Kinematic variables and internal loads (heart rate, blood lactate, and rate of perceived exertion) were measured during each protocol. The athletes maintained peak velocity (PV) and peak power (PP) and exhibited lower internal loads during CLU sets when compared with TRAD sets, whereas they displayed significant decreases in PV during TRAD sets. However, there were no statistically significant differences in PV and PP responses between the TRAD and CLU protocol. The athletes exhibited a significant decrease in PV, whereas PP was increased across each set in the A-CLU protocol, with lower internal loads observed compared with the TRAD protocol. Overall, the training loads used in this study do not appear to maximize the benefits of using CLU set during 3 sets of power snatches performed for 5 repetitions. In addition, A-CLU sets may potentially be useful as a means of maximizing the power output of the athlete.

Study protocol: investigating the feasibility of a hybrid delivery of home-based cluster set resistance training for individuals previously treated for lung cancer

Background

Symptom burden remains a critical concern for individuals with non-small cell lung cancer (NSCLC) following the completion of treatment. The most common symptom clusters, dyspnea (shortness of breath) and fatigue, can contribute to physical decline, reductions in quality of life, and a higher risk of comorbidities and mortality. Dyspnea is a primary limiter of exercise capacity in individuals with lung cancer, resulting in exercise avoidance and an accelerated physical decline. As such, designing resistance training with cluster sets to mitigate symptoms of dyspnea and fatigue may result in improved exercise tolerance. Thus, maintaining the exercise stimulus via cluster sets, combined with improved tolerance of the exercise, could result in the maintenance of physical function and quality of life. The purpose of this study is to investigate the feasibility and preliminary efficacy of a hybrid-delivery home-based cluster-set resistance training program in individuals with NSCLC.

Methods

Individuals with NSCLC (n = 15), within 12 months of completion of treatment, will be recruited to participate in this single-arm feasibility trial. Participants will complete 8 weeks of home-based resistance training designed to minimize dyspnea and fatigue. The hybrid delivery of the program will include supervised sessions in the participants’ home and virtual supervision via video conferencing. The primary outcome of feasibility will be quantified by recruitment rates, retention, acceptability, and intervention fidelity. Exploratory outcomes (dyspnea, fatigue, quality of life, physical function, and body composition) will be assessed pre- and post-intervention.

Discussion

This study will provide important data on the feasibility of delivering this intervention and inform procedures for a future randomized controlled trial.

Trial registration

Record not yet public

The Agreement Between a Portable Contact-Mat and Force-Plates During Bilateral Vertical Jumps

Force plates are commonly used when assessing vertical jumping performance but are not always affordable or practical tools for all testing situations. Twenty-four participants volunteered to take part in a study investigating the agreement between bilateral force plates and a new commercially available contact mat that records jump height, flight-time (FT), and FT of individual limbs during both countermovement (CMJ) and squat (SJ) jumps. Each participant performed six jumps of each type while standing on a contact mat placed upon a pair of in-ground force plates. When compared to the force plate via ordinary least products regression, the contact mat agreed with force plate CMJ and SJ jump height, individual limb FT during CMJs, and left-leg FT during SJs. The bilateral contact mat provided valid assessment of individual limb FT during CMJs, but not SJs. Practitioners can therefore use a bilateral contact mat interchangeably with bilateral force plates to measure SJ and CMJ performance.

Evaluation of High-Intensity Interval Training and Beta-Alanine Supplementation on Efficiency of Electrical Activity and Electromyographic Fatigue Threshold

ABSTRACT

Herda, AA, Smith-Ryan, AE, Kendall, KL, Cramer, JT, and Stout, JR. Evaluation of high-intensity interval training and beta-alanine supplementation on efficiency of electrical activity and electromyographic fatigue threshold. J Strength Cond Res 35(6): 1535-1541, 2021-The purpose of this study was to determine the effects of high-intensity interval training (HIIT) with or without β-alanine (BA) supplementation on the electromyographic fatigue threshold (EMGFT) and efficiency of electrical activity (EEA) in young women. Forty-four women (mean ± SD; age [yrs]: 21.7 ± 3.7; height [cm]: 166.3 ± 6.4; body mass [kg]: 66.1 ± 10.3) were randomly assigned to one of 3 treatment groups. The supplement groups performed HIIT on the cycle ergometer 3 times·wk-1 for 6 weeks. Electromyographic fatigue threshold and EEA were assessed at baseline (PRE), after 3 weeks of training (MID), and after 6 weeks of HIIT (POST). Two 2-way mixed factorial analyses of variance (time [PRE vs. MID vs. POST] × treatment (BA vs. PL vs. CON)] were used to analyze EMGFT and EEA with a predetermined level of significance α of 0.05. For EMGFT, there was no interaction (p = 0.26) and no main effect for time (p = 0.28) nor treatment (p = 0.86); thus, there were no changes in EMGFT regardless of training or supplementation status. For EEA, there was no interaction (p = 0.70) nor treatment (p = 0.79); however, there was a main effect for time (p < 0.01). Our findings indicated that neither training nor supplementation was effective in improving EMGFT in women. Efficiency of electrical activity was altered, potentially because of a learning effect. Coaches and practitioners may not use these tests to monitor training status; however, they may find EEA as a useful tool to track cycling efficiency.

The potential therapeutic effects of creatine supplementation on body composition and muscle function in cancer

Low muscle mass in individuals with cancer has a profound impact on quality of life and independence and is associated with greater treatment toxicity and poorer prognosis. Exercise interventions are regularly being investigated as a means to ameliorate treatment-related adverse effects, and nutritional/supplementation strategies to augment adaptations to exercise are highly valuable. Creatine (Cr) is a naturally-occurring substance in the human body that plays a critical role in energy provision during muscle contraction. Given the beneficial effects of Cr supplementation on lean body mass, strength, and physical function in a variety of clinical populations, there is therapeutic potential in individuals with cancer at heightened risk for muscle loss. Here, we provide an overview of Cr physiology, summarize the evidence on the use of Cr supplementation in various aging/clinical populations, explore mechanisms of action, and provide perspectives on the potential therapeutic role of Cr in the exercise oncology setting.

Effects of Hydrolyzed Whey versus Other Whey Protein Supplements on the Physiological Response to 8 Weeks of Resistance Exercise in College-Aged Males

OBJECTIVE

The objective of this study was to compare the chronic effects of different whey protein forms on body composition and performance when supplemented with resistance training.

METHODS

Resistance-trained men (N = 56, 21.4 ± 0.4 years, 79.5 ± 1.0 kg) participated in an 8-week resistance training regimen (2 upper-body sessions and 2 lower-body sessions per week) and received one of 4 double-blinded treatments: 30 g/serving carbohydrate placebo (PLA) or 30 g/serving protein from either (a) 80% whey protein concentrate (WPC), (b) high-lactoferrin-containing WPC (WPC-L), or (c) extensively hydrolyzed WPC (WPH). All subjects consumed 2 servings of treatment per day; specifically, once immediately before and after training and between meals on nontraining days. Blood collection, one repetition maximum (1RM) testing for bench press and hack squat, and body composition assessment using dual-energy x-ray absorptiometry (DXA) occurred prior to training and 48 hours following the last training session.

RESULTS

Total body skeletal muscle mass increased in all groups (p < 0.0125). There were similar between-group increases in upper-body (4%-7%, analysis of covariance [ANCOVA] interaction p = 0.73) and lower-body (24%-35%, ANCOVA interaction p = 0.85) 1RM strength following the intervention. Remarkably, WPH reduced fat mass (-6%), which was significantly different from PLA (+4.4%, p < 0.0125). No time or between-group differences were present for serum markers of health, metabolism, or muscle damage, with the exception of blood urea nitrogen being significantly lower for WPH than WPC (p < 0.05) following the intervention.

CONCLUSIONS

WPH may augment fat loss but did not provide any other advantages when used in combination with resistance training. More mechanistic research is needed to examine how WPH affects adipose tissue physiology.

Proceedings of the Thirteenth International Society of Sports Nutrition (ISSN) Conference and Expo

P1 Impact of antioxidant-enriched nutrient bar supplementation on the serum antioxidant markers and physical fitness components of track and field athletes

Lalitha Ramaswamy, Supriya Velraja

P2 The effects of phosphatidic acid supplementation on fitness levels in resistance trained women

Guillermo Escalante, Phil Harvey, Michelle Alencar, Bryan Haddock

P3 The effects of phosphatidic acid supplementation on cardiovascular risk factors in resistance trained men

Phil Harvey, Guillermo Escalante, Michelle Alencar, Bryan Haddock

P4 The efficacy of sodium bicarbonate supplementation on physical capacity and selected biochemical markers in elite wrestlers

Krzysztof Durkalec-Michalski, Jan Jeszka, Bogna Zawieja, Tomasz Podgórski

P5 Effects of different nutritional strategies in hydration and physical performance in healthy well-trained males

Ana Paula Trussardi Fayh, Alexandre Hideki Okano, Amanda Maria de Jesus Ferreira

P6 Reduction of plasma creatine concentrations as an indicator of improved bioavailability

Ralf Jäger, Martin Purpura, Roger C Harris

P7 Effect of three different breakfast meals on energy intake and nutritional status in college-age women

Molly M. Krause, Kiley A. Lavanger, Nina O. Allen, Allison E. Lieb, Katie A. Mullen, Joan M. Eckerson

P8 Accuracy of the ASA24® Dietary Recall system for assessing actual dietary intake in normal weight college-age women.

Kiley A. Lavanger, Molly M. Krause, Nina O. Allen, Allison E. Lieb, Katie A. Mullen, Joan M. Eckerson

P9 β-aminoisobutyric acid does not regulate exercise induced UCP-3 expression in skeletal muscle

Elisa Morales, Jeffrey Forsse, Thomas Andre, Sarah McKinley, Paul Hwang, Grant Tinsley, Mike Spillane, Peter Grandjean, Darryn Willoughby

P10 The ability of collegiate football athletes to adhere to sport-specific nutritional recommendations

A. Jagim, G. Wright, J. Kisiolek, M. Meinking, J. Ochsenwald, M. Andre, M.T. Jones, J. M. Oliver

P11 A single session of low-volume high intensity interval exercise improves appetite regulation in overweight men

Victor Araújo Ferreira, Daniel Costa de Souza, Victor Oliveira Albuquerque dos Santos, Rodrigo Alberto Vieira Browne, Eduardo Caldas Costa, Ana Paula Trussardi Fayh

P12 Acute effects of oral peppermint oil ingestion on exercise performance in moderately-active college students

Suresh T. Mathews, Haley D. Bishop, Clara R. Bowen, Yishan Liang, Emily A. West, Rebecca R. Rogers, Mallory R. Marshall, John K. Petrella

P13 Associations in body fat and liver triglyceride content with serum health markers in sedentary and exercised rats fed a ketogenic diet, Western diet or standard chow over a 6-week period

A. Maleah Holland, Wesley C. Kephart, Petey W. Mumford, C. Brooks Mobley, Ryan P. Lowery, Jacob M. Wilson, Michael D. Roberts

P14 Physiological changes following competition in male and female physique athletes: A pilot study

Eric T. Trexler, Katie R. Hirsch, Bill I. Campbell, Meredith G. Mock, Abbie E. Smith-Ryan

P15 Relationship between cognition and hydration status in college students at a large Southwestern university

Kate Zemek, Carol Johnston

P16 Whey protein-derived exosomes increase protein synthesis in C2C12 myotubes

C. Brooks Mobley, Petey W. Mumford, David D. Pascoe, Christopher M. Lockwood, Michael E. Miller, Michael D. Roberts

P17 The effect of three different energy drinks on 1.5-mile running performance, oxygen consumption, and perceived exertion

Gabriel J. Sanders, Willard Peveler, Brooke Warning, Corey A. Peacock

P18 The Ketogenic diet improves rotarod performance in young and older rats

Wesley C. Kephart, Petey W. Mumford, Ryan P. Lowery, Michael D. Roberts, Jacob M. Wilson

P19 Absorption of bonded arginine silicate compared to individual arginine and silicon components

David Sandler, Sara Perez Ojalvo, James Komorowski

P20 Effects of a high (2.4 g/kg) vs. low/moderate (1.2 g/kg) protein intake on body composition in aspiring female physique athletes engaging in an 8-week resistance training program

Bill I. Campbell, Danielle Aguilar, Andres Vargas, Laurin Conlin, Amey Sanders, Paola Fink-Irizarry, Layne Norton, Ross Perry, Ryley McCallum, Matthew R. Wynn, Jack Lenton

P21 Effects of a high (2.4 g/kg) vs. low/moderate (1.2 g/kg) protein intake on maximal strength in aspiring female physique athletes engaging in an 8-week resistance training program

Bill I. Campbell, Chris Gai, Seth Donelson, Shiva Best, Daniel Bove, Kaylee Couvillion, Jeff Dolan, Dante Xing, Kyshia Chernesky, Michael Pawela, Andres D. Toledo, Rachel Jimenez

P22 Monitoring of female collegiate athletes over a competitive season reveals changes in nutritional biomarkers

M. Rabideau, A. Walker, J. Pellegrino, M. Hofacker, B. McFadden, S. Conway, C. Ordway, D. Sanders, R. Monaco, M. S. Fragala, S. M. Arent

P23 Comparison of prediction equations to indirect calorimetry in men and women athletes

Jason D. Stone, Andreas Kreutzer, Jonathan M. Oliver, Jacob Kisiolek, Andrew R. Jagim

P24 Regional variations in sweat-based electrolyte loss and changes in plasma electrolyte content in Division I female athletes over the course of a competitive season

M. Hofacker, A. Walker, J. Pellegrino, M. Rabideau, B. McFadden, S. Conway, D. Sanders, C. Ordway, R. Monaco, M. S. Fragala, S. M. Arent

P25 In-season changes in plasma amino acid levels in Division I NCAA female athletes

Ozlem Tok, Joseph K. Pellegrino, Alan J. Walker, David J. Sanders, Bridget A. McFadden, Meaghan M. Rabideau, Sean P. Conway, Chris E. Ordway, Marissa Bello, Morgan L. Hofacker, Nick S. Mackowski, Anthony J. Poyssick, Eddie Capone, Robert M. Monaco, Maren S. Fragala, Shawn M. Arent

P26 Effects of a ketogenic diet with exercise on serum markers of bone metabolism, IGF-1 and femoral bone mass in rats

Petey W. Mumford, A. Maleah Holland, Wesley C. Kephart, Ryan P. Lowery, C. Brooks Mobley, Romil K. Patel, Annie Newton, Darren T. Beck, Michael D. Roberts, Jacob M. Wilson, Kaelin C. Young

P27 Casein supplementation in trained men and women: morning versus evening

Tobin Silver, Anya Ellerbroek, Richard Buehn, Leo Vargas, Armando Tamayo, Corey Peacock, Jose Antonio

P28 A high protein diet has no harmful effects: a one-year crossover study in resistance-trained males

Anya Ellerbroek, Tobin Silver, Richard Buehn, Leo Vargas, Armando Tamayo, Corey Peacock, Jose Antonio

P29 SUP (Stand-up Paddling) athletes: nutritional intake and body composition

Adam Pollock, Anya Ellerbroek, Tobin Silver, Corey Peacock, Jose Antonio

P30 The effects of 8 weeks of colostrum and bio-active peptide supplementation on body composition in recreational male weight lifters

A. Kreutzer, P. Zavala, S. Fleming, M. Jones, J. M. Oliver, A. Jagim

P31 Effects of a Popular Women’s Thermogenic Supplement During an Energy-Restricted High Protein Diet on Changes in Body Composition and Clinical Safety Markers

Cody T. Haun, Petey W. Mumford, Parker N. Hyde, Ciaran M. Fairman, Wesley C. Kephart, Darren T. Beck, Jordan R. Moon, Michael D. Roberts, Kristina L. Kendall, Kaelin C. Young

P32 Three days of caffeine consumption following caffeine withdrawal yields small strength increase in knee flexors

Geoffrey M Hudson, Tara Hannings, Kyle Sprow, Loretta DiPietro

P33 Comparison of cellular nitric oxide production from various sports nutrition ingredients

Doug Kalman, Sara Perez Ojalvo, James Komorowski

P34 The effects of 8 weeks of bio-active peptide supplementation on training adaptations in recreational male weight lifters

P. Zavala, S. Fleming, M. Jones, J. Oliver, A. Jagim

P35 Effects of MusclePharm Assault Black^TM on lower extremity spinal excitability and postactivation potentiation: A pilot study

Brian Wallace, Haley Bergstrom, Kelly Wallace

P36 Effects of four weeks of Ketogenic Diet alone and combined with High intensity Interval Training or Continuous-Moderate intensity on body composition, lipid profile and physical performance on healthy males

Matias Monsalves-Alvarez, Sebastian Oyharçabal, Victoria Espinoza

P37 Effect of branched-chain amino acid supplementation on creatine kinase, muscular performance, and perceived muscle soreness following acute eccentric exercise

Trisha A. VanDusseldorp, Kurt A. Escobar, Kelly E. Johnson, Nathan Cole, Terence Moriarty, Matthew Stratton, Marvin R. Endito, Christine M. Mermier, Chad M. Kerksick

P38 Effects of endurance training on markers of ribosome biogenesis in rodents fed a high fat diet

Matthew A. Romero, C. Brooks Mobley, Melissa Linden, Grace Margaret-Eleanor Meers, R. Scott Rector, Michael D. Roberts

P39 The effects of acute citrulline-malate on lower-body isokinetic performance in recreationally active individuals

Joshua L Gills, Hocheng Lu, Kimberly Parker, Chris Dobbins, Joshua N Guillory, Braden Romer, David Szymanski, Jordan Glenn

P40 The effect pre-ingested L-isoleucine and L-leucine on blood glucose responses and glycemic hormones in healthy inactive adults: Preliminary data.

Daniel E. Newmire, Eric Rivas, Sarah E. Deemer, Robert Wildman, Victor Ben-Ezra

P41 Does protein and source impact substrate oxidation and energy expenditure during and after moderate intensity treadmill exercise?

C Kerksick, B Gieske, R Stecker, C Smith, K Witherbee

P42 Effects of a pre-workout supplement on peak power and power maintenance during lower and upper body testing

Michael T. Lane, M. Travis Byrd, Zachary Bell, Emily Frith, Lauren M.C. Lane

P43 Effects of a pre-workout supplement on peak power production during lower and upper body testing in college-age females

Michael T. Lane, M. Travis Byrd, Zachary Bell, Emily Frith, Lauren M.C. Lane

P44 A comparison of whey versus casein protein supplementation on resting metabolic rate and body composition: a pilot study

Corey A. Peacock, Tobin A. Silver, Megan Colas, Mauricio Mena, Winter Rodriguez, Gabriel J. Sanders, Jose Antonio

P45 A novel mixed-tocotrienol intervention enhances recovery after eccentric exercise: preliminary findings

Andrea Vansickle, Brittany DiFiore, Stephanie Stepp, Grant Slack, Bridget Smith, Kayla Ruffner, Ronald Mendel, Lonnie Lowery

P46 The effects of post-exercise ingestion of a high molecular weight glucose on cycle performance in female cyclists

Katie R. Hirsch, Meredith G. Mock, Malia M.N. Blue, Eric T. Trexler, Erica J. Roelofs, Abbie E. Smith-Ryan

P47 Inclusive vs. exclusive dieting and the effects on body composition in resistance trained individuals

Laurin Conlin, Danielle Aguilar, Bill I. Campbell, Layne Norton, Katie Coles, Eric T. Trexler, Nic Martinez

P48 A whey protein hydrolysate may positively augment resting metabolism compared to intact whey protein

Jordan M. Joy, Roxanne M. Vogel, Thomas H. Hoover, K. Shane Broughton

P49 Seven days of high and low dose creatine nitrate supplementation I: hepatorenal, glucose and muscle enzyme function

R Dalton, R Sowinski, T Grubic, PB Collins, A Colletta, A Reyes, B Sanchez, M Kozehchain, YP Jung, C Rasmussen, P Murano, CP Earnest, M Greenwood, RB Kreider

P50 Seven days of high and low dose creatine nitrate supplementation II: performance

T Grubic, R Dalton, R Sowinski, PB Collins, A Colletta, A Reyes, B Sanchez, M Kozehchain, YP Jung, C Rasmussen, P Murano, CP Earnest, M Greenwood, RB Kreider

P51 Seven days of high and low dose creatine nitrate supplementation III: hemodynamics

R Sowinski, R Dalton, T Grubic, PB Collins, A Colletta, A Reyes, B Sanchez, M Kozehchain, YP Jung, C Rasmussen, P Murano, CP Earnest, M Greenwood, RB Kreider

P52 The efficacy of a β-hydroxy-β-methylbutyrate supplementation on physical capacity, body composition and biochemical markers in highly-trained combat sports athletes

Krzysztof Durkalec-Michalski, Jan Jeszka, Tomasz Podgórski

P53 Does protein and source impact substrate oxidation and energy expenditure during and after moderate intensity treadmill exercise?

C Kerksick, B Gieske, R Stecker, C Smith, K Witherbee

P54 Effects of 30 days of Cleanse™ supplementation on measure of body composition, waist circumference, and markers of gastrointestinal distress in females

Stacie Urbina, Emily Santos, Katelyn Villa, Alyssa Olivencia, Haley Bennett, Marissa Lara, Cliffa Foster, Colin Wilborn, Lem Taylor

P55 The effects of moderate- versus high-load training on body composition, muscle growth, and performance in college aged females

Jason M Cholewa, Amy Hewins, Samantha Gallo, Ashley Micensky, Christian De Angelis, Christopher Carney, Bill Campbell, Laurin Conlin, Layne Norton, Fabricio Rossi

P56 Effect of a multi-ingredient preworkout supplement on cognitive function and perceptions of readiness to perform

MS Koozehchian, PB Collins, R Sowinski, T Grubic, R Dalton, A O’Connor, SY Shin, Y Peter Jung, BK Sanchez, A Coletta, M Cho, A Reyes, C Rasmussen, CP Earnest, PS Murano, M Greenwood, RB Kreider

Estimating fat-free mass in elite-level male rowers: a four-compartment model validation of laboratory and field methods

The purpose of this study was to investigate the accuracy of fat-free mass (FFM) estimates from two-compartment (2C) models including air displacement plethysmography (ADP), ultrasound (US), near-infrared interactance (NIR), and the Jackson and Pollock skinfold equation (SKF) against a criterion four-compartment (4C) model in elite male rowers.

METHODS

Twenty-three elite-level male rowers (mean± SD; age 24.6 ± 2.2 years; stature: 191.4 ± 7.2 cm; mass: 87.2 ± 11.2 kg) participated in this investigation. All body composition assessments were performed on the same day in random order, except for hydrostatic weighing (HW), which was measured last. FFM was evaluated using a 4C model, which included total body water from bioimpedance spectroscopy, body volume from HW, and total body bone mineral via dual-energy X-ray absorptiometry. The major findings of the study were that the 2C models evaluated overestimated FFM and should be considered with caution for the assessment of FFM in elite male rowers. Future studies should use multiple-compartment models, with measurement of TBW and bone mineral content, for the estimation of FFM.

Ingesting a preworkout supplement containing caffeine, creatine, β-alanine, amino acids, and B vitamins for 28 days is both safe and efficacious in recreationally active men

The purpose of this study was to determine the safety and efficacy of consuming a preworkout supplement (SUP) containing caffeine, creatine, β-alanine, amino acids, and B vitamins for 28 days. We hypothesized that little to no changes in kidney and liver clinical blood markers or resting heart rate and blood pressure (BP) would be observed. In addition, we hypothesized that body composition and performance would improve in recreationally active males after 28 days of supplementation. In a double-blind, placebo-controlled study, participants were randomly assigned to ingest one scoop of either the SUP or placebo every day for 28 days, either 20 minutes before exercise or ad libitum on nonexercise days. Resting heart rate and BP, body composition, and fasting blood samples were collected before and after supplementation. Aerobic capacity as well as muscular strength and endurance were also measured. Significant (P < .05) main effects for time were observed for resting heart rate (presupplementation, 67.59 ± 7.90 beats per minute; postsupplementation, 66.18 ± 7.63 beats per minute), systolic BP (presupplementation, 122.41 ± 11.25 mm Hg; postsupplementation, 118.35 ± 11.58 mm Hg), blood urea nitrogen (presupplementation, 13.12 ± 2.55 mg/dL; postsupplementation, 15.24 ± 4.47 mg/dL), aspartate aminotransferase (presupplementation, 34.29 ± 16.48 IU/L; postsupplementation, 24.76 ± 4.71 IU/L), and alanine aminotransferase (presupplementation, 32.76 ± 19.72 IU/L; postsupplementation, 24.88 ± 9.68 IU/L). Significant main effects for time were observed for body fat percentage (presupplementation, 15.55% ± 5.79%; postsupplementation, 14.21% ± 5.38%; P = .004) and fat-free mass (presupplementation, 70.80 ± 9.21 kg; postsupplementation, 71.98 ± 9.27 kg; P = .006). A significant decrease in maximal oxygen consumption (presupplementation, 47.28 ± 2.69 mL/kg per minute; postsupplementation, 45.60 ± 2.81 mL/kg per minute) and a significant increase in percentage of oxygen consumption per unit time at which ventilatory threshold occurred (presupplementation, 64.38% ± 6.63%; postsupplementation, 70.63% ± 6.39%) and leg press one-repetition maximum (presupplementation, 218.75 ± 38.43 kg; postsupplementation, 228.75 ± 44.79 kg) were observed in the SUP only. No adverse effects were noted for renal and hepatic clinical blood markers, resting heart rate, or BP. Supplements containing similar ingredients and doses should be safe for ingestion periods lasting up to 28 days in healthy, recreationally trained, college-aged men.

Characterization of the work-time relationship during cross-country ski ergometry

The purpose of this study was to examine the validity and reliability of estimated parameters of the work-time relationship during cross-country ski ergometry using the traditional multi-trial critical power (CP) test and a 3 min 'all-out' test (3MT). Fourteen recreationally active male participants (mean ± SD; age: 22.14 ± 2.85 yrs; height: 177.09 ± 6.57 cm; weight: 85.68 ± 13.56 kg) completed three testing visits. All testing was conducted using an upper-body ergometer (SkiErg, Concept2, Inc., Morrisville, VT). A graded exercise test was used to determined maximal oxygen uptake (VO2peak). Two separate 3MT sessions were used to determine oxygen uptake (VO23MT), end-test power (EP), work above end-test power (WEP) and end stroke rate (ESR). Additionally, three time trials completed in a single day at simulated distances of 300 m, 650 m and 1000 m were used to estimate CP, W' and critical stroke rate (CSR). VO2peak (3.65 ± 0.50 l · min(-1)) and VO23MT (3.59 ± 0.4 l · min(-1)) were not significantly different (p = 0.162). Intraclass correlation coefficients for EP, WEP and ESR were 0.809, 0.611 and 0.783, respectively. EP (148 ± 33 W) and CP (157 ± 49 W), were not significantly different between the testing methodologies (p = 0.290) and were highly correlated (r = 0.780). WEP (8.4 ± 3.0 kJ) and W' (8.3 ± 3.0 kJ) were similar (p = 0.947) but not related (r = 0.119), while ESR (45 ± 7 spm) and CSR (47 ± 7 spm) values were not significantly different (p = 0.238) and moderately correlated (r = 0.498). The 3MT using ski ergometry was shown to produce concurrently valid results with the traditional multi-trial CP test for CP and CSR, but not W', and elicited similar maximal oxygen uptake values when compared to a graded exercise test.

Simplified method of clinical phenotyping for older men and women using established field-based measures

The purpose of this investigation was to determine body composition classification using field-based testing measurements in healthy elderly men and women. The use of isoperformance curves is presented as a method for this determination. Baseline values from 107 healthy Caucasian men and women, over the age of 65years old, who participated in a separate longitudinal study, were used for this investigation. Field-based measurements of age, height, weight, body mass index (BMI), and handgrip strength were recorded on an individual basis. Relative skeletal muscle index (RSMI) and body fat percentage (FAT%) were determined by dual-energy X-ray absorptiometry (DXA) for each participant. Sarcopenia cut-off values for RSMI of 7.26kg·m(-2) for men and 5.45kg·m(-2) for women and elderly obesity cut-off values for FAT% of 27% for men and 38% for women were used. Individuals above the RSMI cut-off and below the FAT% cut-off were classified in the normal phenotype category, while individuals below the RSMI cut-off and above the FAT% cut-off were classified in the sarcopenic-obese phenotype category. Prediction equations for RSMI and FAT% from sex, BMI, and handgrip strength values were developed using multiple regression analysis. The prediction equations were validated using double cross-validation. The final regression equation developed to predict FAT% from sex, BMI, and handgrip strength resulted in a strong relationship (adjusted R(2)=0.741) to DXA values with a low standard error of the estimate (SEE=3.994%). The final regression equation developed to predict RSMI from the field-based testing measures also resulted in a strong relationship (adjusted R(2)=0.841) to DXA values with a low standard error of the estimate (SEE=0.544kg·m(-2)). Isoperformance curves were developed from the relationship between BMI and handgrip strength for men and women with the aforementioned clinical phenotype classification criteria. These visual representations were used to aid in the classification and evaluation of sarcopenia, obesity, and sarcopenic-obesity in elderly individuals. Future research should replicate the current findings with an increased sample size and the development of tailored interventions for each body composition category.

Predicting maximal aerobic capacity (VO2max) from the critical velocity test in female collegiate rowers

The objective of this study was to examine the relationship between the critical velocity (CV) test and maximal oxygen consumption (VO2max) and develop a regression equation to predict VO2max based on the CV test in female collegiate rowers. Thirty-five female (mean ± SD; age, 19.38 ± 1.3 years; height, 170.27 ± 6.07 cm; body mass, 69.58 ± 0.3 1 kg) collegiate rowers performed 2 incremental VO2max tests to volitional exhaustion on a Concept II Model D rowing ergometer to determine VO2max. After a 72-hour rest period, each rower completed 4 time trials at varying distances for the determination of CV and anaerobic rowing capacity (ARC). A positive correlation was observed between CV and absolute VO2max (r = 0.775, p < 0.001) and ARC and absolute VO2max (r = 0.414, p = 0.040). Based on the significant correlation analysis, a linear regression equation was developed to predict the absolute VO2max from CV and ARC (absolute VO2max = 1.579[CV] + 0.008[ARC] - 3.838; standard error of the estimate [SEE] = 0.192 L·min(-1)). Cross validation analyses were performed using an independent sample of 10 rowers. There was no significant difference between the mean predicted VO2max (3.02 L·min(-1)) and the observed VO2max (3.10 L·min(-1)). The constant error, SEE and validity coefficient (r) were 0.076 L·min(-1), 0.144 L·min(-1), and 0.72, respectively. The total error value was 0.155 L·min(-1). The positive relationship between CV, ARC, and VO2max suggests that the CV test may be a practical alternative to measuring the maximal oxygen uptake in the absence of a metabolic cart. Additional studies are needed to validate the regression equation using a larger sample size and different populations (junior- and senior-level female rowers) and to determine the accuracy of the equation in tracking changes after a training intervention.

An alternative approach to the Army Physical Fitness Test two-mile run using critical velocity and isoperformance curves

The purpose of this study was to evaluate the use of critical velocity (CV) and isoperformance curves as an alternative to the Army Physical Fitness Test (APFT) two-mile running test. Seventy-eight men and women (mean +/- SE; age: 22.1 +/- 0.34 years; VO2(MAX): 46.1 +/- 0.82 mL/kg/min) volunteered to participate in this study. A VO2(MAX) test and four treadmill running bouts to exhaustion at varying intensities were completed. The relationship between total distance and time-to-exhaustion was tracked for each exhaustive run to determine CV and anaerobic running capacity. A VO2(MAX) prediction equation (Coefficient of determination: 0.805; Standard error of the estimate: 3.2377 mL/kg/min) was developed using these variables. Isoperformance curves were constructed for men and women to correspond with two-mile run times from APFT standards. Individual CV and anaerobic running capacity values were plotted and compared to isoperformance curves for APFT 2-mile run scores. Fifty-four individuals were determined to receive passing scores from this assessment. Physiological profiles identified from this procedure can be used to assess specific aerobic or anaerobic training needs. With the use of time-to-exhaustion as opposed to a time-trial format used in the two-mile run test, pacing strategies may be limited. The combination of variables from the CV test and isoperformance curves provides an alternative to standardized time-trial testing.

Ingesting a pre-workout supplement containing caffeine, B-vitamins, amino acids, creatine, and beta-alanine before exercise delays fatigue while improving reaction time and muscular endurance

BACKGROUND

The purpose of this study was to determine the effects of the pre-workout supplement Assault™ (MusclePharm, Denver, CO, USA) on upper and lower body muscular endurance, aerobic and anaerobic capacity, and choice reaction time in recreationally-trained males. Subjective feelings of energy, fatigue, alertness, and focus were measured to examine associations between psychological factors and human performance.

METHODS

Twelve recreationally-trained males participated in a 3-week investigation (mean +/- SD, age: 28 +/- 5 y, height: 178 +/- 9 cm, weight: 79.2 +/- 15.7 kg, VO2max: 45.7 +/- 7.6 ml/kg/min). Subjects reported to the human performance laboratory on three separate occasions. All participants completed a baseline/familiarization day of testing that included a maximal graded exercise test for the determination of aerobic capacity (VO2max), one-rep maximum (1-RM) for bench and leg press to determine 75% of 1-RM, choice reaction tests, and intermittent critical velocity familiarization. Choice reaction tests included the following: single-step audio and visual, one-tower stationary protocol, two-tower lateral protocol, three-tower multi-directional protocol, and three-tower multi-directional protocol with martial arts sticks. Subjects were randomly assigned to ingest either the supplement (SUP) or the placebo (PL) during Visit 2. Subjects were provided with the cross-over treatment on the last testing visit. Testing occurred 20 min following ingestion of both treatments.

RESULTS

Significant (p < 0.05) main effects for the SUP were observed for leg press (SUP: 13 ± 6 reps, PL: 11 ± 3 reps), perceived energy (SUP: 3.4 ± 0.9, PL: 3.1 ± 0.8), alertness (SUP: 4.0 ± 0.7, PL: 3.5 ± 0.8), focus (SUP: 4.1 ± 0.6, PL: 3.5 ± 0.8), choice reaction audio single-step (SUP: 0.92 ± 0.10 s, PL: 0.97 ± 0.11 s), choice reaction multi-direction 15 s (SUP: 1.07 ± 0.12 s, PL: 1.13 ± 0.14 s), and multi-direction for 30 s (SUP: 1.10 ± 0.11 s, PL: 1.14 ± 0.13 s).

CONCLUSIONS

Ingesting the SUP before exercise significantly improved agility choice reaction performance and lower body muscular endurance, while increasing perceived energy and reducing subjective fatigue. These findings suggest that the SUP may delay fatigue during strenuous exercise.

Ergolytic/ergogenic effects of creatine on aerobic power

This study evaluated the effects of creatine (Cr) loading and sex differences on aerobic running performance. 27 men (mean±SD; age: 22.2±3.1 years, ht: 179.5±8.7 cm, wt: 78.0±9.8 kg) and 28 women (age: 21.2±2.1 years, ht: 166.0±5.8 cm, wt: 63.4±8.9 kg) were randomly assigned to either creatine (Cr, di-creatine citrate; n=27) or a placebo (PL; n=28) group, ingesting 1 packet 4 times daily (total of 20 g/day) for 5 days. Aerobic power (maximal oxygen consumption: VO2max) was assessed before and after supplementation using open circuit spirometry (Parvo-Medics) during graded exercise tests on a treadmill. 4 high-speed runs to exhaustion were conducted at 110, 105, 100, and 90% of peak velocity to determine critical velocity (CV). Distances achieved were plotted over times-to-exhaustion and linear regression was used to determine the slopes (critical velocity, CV) assessing aerobic performance. The results indicated that Cr loading did not positively or negatively influence VO2max, CV, time to exhaustion or body mass (p>0.05). These results suggest Cr supplementation may be used in aerobic running activities without detriments to performance.

Mechanical scale and load cell underwater weighing: a comparison of simultaneous measurements and the reliability of methods

Both load cell and mechanical scale-based hydrostatic weighing (HW) systems are used for the measurement of underwater weight. However, there has been no direct comparison of the 2 methods. The purpose of the current investigation was to simultaneously compare a load cell and mechanical scale for use in HW. Twenty-seven men and women (mean ± SD, age: 22 ± 2 years) participated in the 2-day investigation. Each subject completed 2 HW assessments 24 hours apart. Single-day comparisons of all trials for both days revealed no significant difference between the mechanical scale and the load cell (mean difference < 0.016 kg, p > 0.05). True underwater weight values were not significantly different between methods for either days (mean difference < 0.014 kg, p > 0.05) and accounted for a mean difference in percent fat (%FAT) of <0.108%. The 95% limits of agreement indicated a maximum difference between methods of 0.53% FAT. Both methods produced similar reliability SEM values (mechanical SEM < 0.72%FAT, load cell SEM < 0.75%FAT). In conclusion, there was no difference between mechanical scale and load cell measurements of underwater weights and the added precision of the load cell only marginally (<0.16%FAT) improved day-to-day reliability. Either a mechanical scale or load cell can be used for HW with similar accuracy and reliability in young adults with a body mass index of 18.7-34.4 (5-25%FAT).

Determination of aerobic and anaerobic performance: a methodological consideration

This study was designed to compare critical velocity (CV) and anaerobic running capacity (ARC) estimates using the criterion method of four runs with two and three combination bouts to reduce the time and energy demands of the subjects. Twenty-eight men and women (mean ± SD; age = 21.9 ± 3.0 years; stature = 171.7 ± 9.7 cm; body mass = 69.7 ± 13.4 kg) performed an incremental test to exhaustion to determine peak velocity (PV) at maximal oxygen consumption (VO(2)max). Four high-speed runs to exhaustion were conducted on separate days with 110% PV, 90% PV (day 1), 100% PV and 105% PV (day 2). The distances achieved were plotted over the times to exhaustion. Linear regression was used to determine the slopes (CV) and y-intercepts (ARC) using four velocities and the other ten possible velocity combinations. Two runs to exhaustion, at 90% PV and 110% PV, produced similar CV and ARC results to the standard four bouts (ICC = 0.995, SEM = 0.298). Three velocities at 90% PV, 100% PV and 110% PV also resulted in no differences from the criterion method (ICC = 0.999, SEM = 0.075). These results suggest that CV and ARC can be estimated from two velocities, but to ensure a linear relationship, three velocities are recommended.

Low-calorie energy drink improves physiological response to exercise in previously sedentary men: a placebo-controlled efficacy and safety study

Energy drink use has grown despite limited research to support efficacy or safety and amid concerns when combined with exercise. The purpose of this study was to assess the effects of 10 weeks of once-daily energy drink consumption or energy drink consumption with exercise on measures of body composition, cardiorespiratory fitness, strength, mood, and safety in previously sedentary males. Thirty-eight males were randomly assigned to energy drink + exercise (EX-A), energy drink (NEX-A), placebo + exercise (EX-B), or placebo (NEX-B). All participants consumed 1 drink per day for 10 weeks; EX-A and EX-B participated in 10 weeks of resistance and endurance exercise. Testing was performed before (PRE) and after (POST) the 10-week intervention. No significant (p > 0.05) changes were observed for body composition, fitness, or strength in NEX-A; however, significantly greater decreases in fat mass and percentage body fat and increases in VO2peak were observed in EX-A versus EX-B. Ventilatory threshold (VT), minute ventilation, VO2 at VT, and power output at VT improved significantly PRE to POST in EX-A but not in EX-B or nonexercising groups. Clinical markers for hepatic, renal, cardiovascular, and immune function, as determined by PRE and POST blood work revealed no adverse effects in response to the energy drink. Mood was not affected by energy drink use. Absent energy restriction or other dietary controls, chronic ingestion of a once-daily low-calorie energy drink appears ineffective at improving body composition, cardiorespiratory fitness, or strength in sedentary males. However, when combined with exercise, preworkout energy drink consumption may significantly improve some physiological adaptations to combined aerobic and resistance training.

The effects of creatine loading and gender on anaerobic running capacity

Creatine (Cr) loading consists of short-term, high-dosage Cr supplementation and has been shown to increase intramuscular total Cr content. Increases in body weight (BW) have been shown to result from Cr loading, with differences by gender, and increased BW may impact weight-bearing exercise. The critical velocity (CV) test is used to quantify the relationship between total running distance and time to exhaustion. The CV test provides the variable, anaerobic running capacity (ARC), which is an estimate of the anaerobic energy reserves in muscle. The purpose of this study was to examine the effects of gender and Cr loading on ARC. Fifty moderately trained men and women volunteered to participate in this randomized, double-blinded, placebo (PL)-controlled, repeated-measures study. After a familiarization session, a 3-day testing procedure was conducted. A maximal oxygen consumption test VO(2)max) on a treadmill was performed on day 1 to establish the maximum velocity (Vmax) at VO(2)max and to record BW. Days 2 and 3 involved treadmill running at varying percentages of Vmax. Participants were randomly assigned to either the Cr or PL group and received 20 packets of the Cr supplement (1 packet = 5 g Cr citrate, 18 g dextrose) or 20 packets of the PL (1 packet = 18 g dextrose). After consuming 4 packets daily for 5 consecutive days, the 3-day testing procedure was repeated. The male Cr loading group exhibited a 23% higher (p = 0.003) ARC compared to the PL group. Nonsignificant BW increases were found for the Cr groups. These findings suggest that Cr loading may be an effective strategy for improving ARC in men, but not in women, and revealed only nonsignificant increases in BW. Creatine loading may be used before competition by athletes to provide improvements in high-intensity, short-duration activities.

Physiological effects of caffeine, epigallocatechin-3-gallate, and exercise in overweight and obese women

The aim of this study was to evaluate the combined effects of a 10-week exercise program with ingestion of caffeine and epigallocatechin-3-gallate (EGCG) on body composition, cardiovascular fitness, and strength in overweight and obese women. In a double-blind, placebo-controlled approach, overweight and obese women (n = 27) were randomly assigned to treatment groups with exercise (an active-supplementing group with exercise (EX-Act) and a placebo group with exercise (EX-PL)) or without exercise (an active-supplementing group without exercise (NEX-Act) and a placebo group without exercise (NEX-PL)). All participants consumed 1 drink per day for 10 weeks; EX-Act and EX-PL participated in a concurrent endurance and resistance training program. Changes in body composition were assessed using a 4-compartment model. Changes in muscle mass (MM) were evaluated using a DXA-derived appendicular lean–soft tissue equation. There was a significant time × treatment interaction for MM (p = 0.026) and total cholesterol (TC) (p = 0.047), and a significant time × training interaction for peak oxygen consumption (p = 0.046) and upper-body and lower-body strength (p < 0.05). Significant differences between the EX groups and NEX groups for percentage change in MM and peak oxygen consumption, and upper-body and lower-body strength, were revealed. Clinical markers for hepatic and renal function revealed no adverse effects. TC significantly decreased for the active-supplementing groups (EX-Act, NEX-Act). The current study suggests that implementing a caffeine–EGCG-containing drink prior to exercise may improve MM, fitness, and lipid profiles in overweight women.

The effects of a pre-workout supplement containing caffeine, creatine, and amino acids during three weeks of high-intensity exercise on aerobic and anaerobic performance

Background

A randomized, single-blinded, placebo-controlled, parallel design study was used to examine the effects of a pre-workout supplement combined with three weeks of high-intensity interval training (HIIT) on aerobic and anaerobic running performance, training volume, and body composition.

Methods

Twenty-four moderately-trained recreational athletes (mean ± SD age = 21.1 ± 1.9 yrs; stature = 172.2 ± 8.7 cm; body mass = 66.2 ± 11.8 kg, VO₂max = 3.21 ± 0.85 l·min^-1, percent body fat = 19.0 ± 7.1%) were assigned to either the active supplement (GT, n = 13) or placebo (PL, n = 11) group. The active supplement (Game Time^®, Corr-Jensen Laboratories Inc., Aurora, CO) was 18 g of powder, 40 kcals, and consisted of a proprietary blend including whey protein, cordyceps sinensis, creatine, citrulline, ginseng, and caffeine. The PL was also 18 g of powder, 40 kcals, and consisted of only maltodextrin, natural and artificial flavors and colors. Thirty minutes prior to all testing and training sessions, participants consumed their respective supplements mixed with 8-10 oz of water. Both groups participated in a three-week HIIT program three days per week, and testing was conducted before and after the training. Cardiovascular fitness (VO₂max) was assessed using open circuit spirometry (Parvo-Medics TrueOne^® 2400 Metabolic Measurement System, Sandy, UT) during graded exercise tests on a treadmill (Woodway, Pro Series, Waukesha, WI). Also, four high-speed runs to exhaustion were conducted at 110, 105, 100, and 90% of the treadmill velocity recorded during VO₂max, and the distances achieved were plotted over the times-to-exhaustion. Linear regression was used to determine the slopes (critical velocity, CV) and y-intercepts (anaerobic running capacity, ARC) of these relationships to assess aerobic and anaerobic performances, respectively. Training volumes were tracked by summing the distances achieved during each training session for each subject. Percent body fat (%BF) and lean body mass (LBM) were assessed with air-displacement plethysmography (BOD POD^®, Life Measurement, Inc., Concord, CA).

Results

Both GT and PL groups demonstrated a significant (p = 0.028) increase in VO₂max from pre- to post-training resulting in a 10.3% and 2.9% improvement, respectively. CV increased (p = 0.036) for the GT group by 2.9%, while the PL group did not change (p = 0.256; 1.7% increase). ARC increased for the PL group by 22.9% and for the GT group by 10.6%. Training volume was 11.6% higher for the GT versus PL group (p = 0.041). %BF decreased from 19.3% to 16.1% for the GT group and decreased from 18.0% to 16.8% in the PL group (p = 0.178). LBM increased from 54.2 kg to 55.4 kg (p = 0.035) for the GT group and decreased from 52.9 kg to 52.4 kg in the PL group (p = 0.694).

Conclusion

These results demonstrated improvements in VO₂max, CV, and LBM when GT is combined with HIIT. Three weeks of HIIT alone also augmented anaerobic running performance, VO₂max and body composition.

The effects of four weeks of creatine supplementation and high-intensity interval training on cardiorespiratory fitness: a randomized controlled trial

Background

High-intensity interval training has been shown to be a time-efficient way to induce physiological adaptations similar to those of traditional endurance training. Creatine supplementation may enhance high-intensity interval training, leading to even greater physiological adaptations. The purpose of this study was to determine the effects of high-intensity interval training (HIIT) and creatine supplementation on cardiorespiratory fitness and endurance performance (maximal oxygen consumption (VO_2PEAK), time-to-exhaustion (VO_2PEAKTTE), ventilatory threshold (VT), and total work done (TWD)) in college-aged men.

Methods

Forty-three recreationally active men completed a graded exercise test to determine VO_2PEAK, VO_2PEAKTTE, and VT. In addition, participants completed a time to exhaustion (TTE) ride at 110% of the maximum workload reached during the graded exercise test to determine TWD (TTE (sec) × W = J). Following testing, participants were randomly assigned to one of three groups: creatine (creatine citrate) (Cr; n = 16), placebo (PL; n = 17), or control (n = 10) groups. The Cr and PL groups completed four weeks of HIIT prior to post-testing.

Results

Significant improvements in VO_2PEAK and VO_2PEAKTTE occurred in both training groups. Only the Cr group significantly improved VT (16% vs. 10% improvement in PL). No changes occurred in TWD in any group.

Conclusion

In conclusion, HIIT is an effective and time-efficient way to improve maximal endurance performance. The addition of Cr improved VT, but did not increase TWD. Therefore, 10 g of Cr per day for five days per week for four weeks does not seem to further augment maximal oxygen consumption, greater than HIIT alone; however, Cr supplementation may improve submaximal exercise performance.