- Howerton, D., Shaw, H., Willerer, M., & Littlefield, L. (2020, November). Step it up: A physical activity intervention study [Paper presentation]. Student Scholars Symposium, Nashville, TN. Abstract
Introduction: Cardiovascular risk factors such as hypertension, abdominal obesity, and high body fat are associated with sedentary behavior and lack of physical activity (PA). Some studies have shown that increasing PA, specifically in the form of increasing number of steps per day, can lower cardiovascular risk factors such as blood pressure (BP) and waist circumference (WC). Methods: This 4-week PA intervention will analyze the effects of increased daily steps on BP, WC, and body fat percentage in 11 healthy adults currently taking fewer than 10,000 steps per day. A baseline week of daily steps will be measured using a pedometer and a daily average will be calculated. Baseline BP, WC (measured in duplicate at the level of the umbilicus), and body fat (measured using InBody 570) will be obtained. Participants will then be asked to increase their average daily steps by 3,000 for 4 weeks while maintaining all usual dietary and activity habits. BP, WC, and body fat will then be reassessed. The data collected will be analyzed using dependent sample t-tests. Hypothesis: We hypothesize that an increase in daily PA will significantly lower BP, WC, and body fat over the course of the intervention. Discussion: Previous research has demonstrated that a modest, short-term increase in PA may lead to improved markers of cardiovascular health in the average sedentary adult. We aim to contribute to this body of knowledge through our intervention examining the effects of increasing PA by 3,000 steps per day.
- Jones, M. D., Morimune, J., Littlefield, L., & Townsend, J. (2020, November). Acute protease supplementation does not alter the endocrine response to resistance exercise in trained males [Paper presentation]. Student Scholars Symposium, Nashville, TN. Abstract
Proteases aid in the hydrolysis of proteins into smaller peptides and oral protease supplementation may alter the endocrine response to exercise, promoting improved recovery. Purpose: To determine if protease supplementation immediately after an exercise session influences circulating testosterone, cortisol, insulin, insulin-like growth factor-1 (IGF-1), and growth hormone (GH) concentrations. Methods: Ten resistance-trained males (24.1±4.1yr, 69.6±6.8 kg 179±8.6 cm) completed 3 acute lower-body resistance exercise sessions consisting of 4 sets of leg press and leg extension exercises in a randomized, crossover fashion. Each exercise was performed at 75% of each participant’s previously determined one repetition maximum, for 8-10 repetitions, with 90 seconds of rest between sets. Following exercise, participants consumed one of 3 treatments (W: 26g whey; PW: 26g whey + 250mg of a protease enzyme blend; PL: non-caloric control). Blood draws were obtained at baseline (BL), immediatelypost (IP), 1-hour (1H) and 3-hours post-exercise (3H) and analyzed for testosterone, cortisol, insulin, IGF-1, and GH. Data for each hormone were analyzed with a 2-way repeated measures analysis of variance (ANOVA). Results: Significant main effects for time (p<0.05) were observed for all hormones. There was a significant decrease in testosterone at IP (p=0.007), 1H (p<0.001), and 3H (p<0.001). There was a significant decrease in cortisol at all time points (p<0.001) compared to BL. There were significant increases in insulin, IGF-1, and growth hormone at all time points (p<0.001) following exercise. Conclusion: Neither protease nor protein supplementation appear to alter the endocrine response to resistance exercise in trained males compared to a control.
- Morimune, J., & Townsend, J. (2020, November). The effects of digestive enzymes on amino acid response to resistance exercise in trained males [Paper presentation]. Student Scholars Symposium, Nashville, TN. Abstract
The aim of the current study was to examine the efficacy of whey protein ingestion with or without a digestive enzyme complex on amino acid (AA) availability following acute lower-body resistance exercise. Following an overnight fast, ten resistance trained men performed lower-body acute resistance exercises consisting of four sets each of the leg press and leg extension exercises followed by consumption of one of three drinks of equivalent volume, taste, and appearance which consisted of either: (a) 26g whey protein + 250 mg protease supplement + whey (PW) (b) 26g whey protein (W), or (c) a non-caloric flavored water drink (PL). Results showed significant main effects for time (p<0.001) and time x group interactions (p<0.001) were found for leucine, BCAA, and EAA. WPH drink resulted in significantly greater plasma leucine, BCAA and EAA concentrations at 30 min compared to PL (p<0.001) while not different than W. Leucine was significantly elevated at 30min (p=0.007) and EAAs at 180min (p=0.004) compared to 0min for WPH. The AUC for WPH and W were both significantly elevated groups for leucine, BCAAs and EAAs compared to PL (p<0.001). While no significant differences were found between the W and WPH supplementation groups during the 3-hr period after resistance training; the WPH group produced significantly greater leucine concentrations at 30min and in EAAs at 180min than PL compared to 0m. Results indicate that WPH may provide a more rapid absorption and longer lasting concentration of AAs in the blood after exercise compared with W or PL.
- Townsend, J. R., Morimune, J. E., Jones, M. D., Beuning, C. N., Haase, A. A., Boot, C. M., Heffington, S. H., Littlefield, L. A., Henry, R. N., Marshall, A. C., VanDusseldorp, T. A., Feito, Y., & Mangine, G. T. (2020). The effect of Prohydrolase(®) on the amino acid and intramuscular anabolic signaling response to resistance exercise in trained males. Sports (Basel, Switzerland), 8(2), E13. https://doi.org/10.3390/sports8020013
- Washington, S., Zimmerman, G. A., Mullen, R., Lunney, S., & Littlefield, L. (2020, November). The effects of caffeine dose on lower extremity muscle fatigue in resistance trained individuals [Paper presentation]. Student Scholars Symposium, Nashville, TN. Abstract
Introduction: Caffeine has been used as a chief substance to enhance exercise performance. Vast evidence exists detailing the effect of caffeine consumption on improving aerobic performance, yet, research is scarce in explaining performance effects on resistance training and anaerobic systems. More work is needed to determine caffeine’s effect on resistance training in recreationally active individuals. Purpose: The purpose of this investigation is to determine the effects of caffeine supplementation on repetitions to fatigue during a leg extension and leg press exercise. This study will provide an overview on the influence that caffeine has on the human body, its ergogenic effect, and specifically, its anaerobic influence. Methods: A blinded, randomized, repeated measures design will be used. The sample in this study will include 10-12 males and females who regularly consume caffeine and are resistance trained. Each participant will fill out a PAR-Q+ prior to completing a one repetition maximum (1RM) test for the leg press and leg extension. Repetitions to fatigue will be performed 45-minutes after drinking either placebo (maltodextrin), 3mg/kg, or 7mg/kg of caffeine anhydrous. Repetitions to fatigue will consist of participants completing as many repetitions as possible at 80% of 1RM. Data analysis will be performed through the JMP software system by a repeated measures ANOVA test. Hypotheses: It is hypothesized that the effects of caffeine will delay fatigue on anaerobic performance using resistance exercises for lower extremity muscles.
- Zimmerman, G. A., & Townsend, J. (2020, November). Low-dose vitamin D supplementation does not prevent 25(oh) vitamin D decline in college students [Paper presentation]. Student Scholars Symposium, Nashville, TN. Abstract
Vitamin D deficiency is prevalent among active adults; therefore, multivitamin products are consumed to correct this deficiency, but many multivitamins are often under-dosed compared to current evidenced-based recommendations. Purpose: To compare the effects of two different forms of low-dose multivitamins on 25(OH) vitamin D status following 10-weeks of supplementation. Methods: Thirty-four healthy males (n=14; 20.1y, 163cm, 71.7kg) and females (n=20; 22.1y, 153.4cm, 69.9kg) participated in this randomized, double-blind, placebo-controlled study. At the beginning of the 10-week intervention, participants provided a resting, fasted baseline blood sample and were randomly assigned to a liquid multivitamin supplement (LIQ; n=11), multivitamin capsule (CAP; n=11), or placebo group (PL; n=12). Participants took their respective supplement daily for 10 weeks. The LIQ and CAP supplement both contained 268 IU of Vitamin D. After the 10-weeks, all participants reported back to the laboratory for a resting, fasted blood sample. Plasma samples were assayed for 25(OH) vitamin D concentrations. Data were analyzed using a 2-way repeated measures analysis of variance (ANOVA). Results: There was a main effect for time (F=11.86, p=0.002, η2 =0.227) with 25(OH) vitamin D concentrations significantly lower (∆: -7.8-14.9ng/ mL) at post-testing. Further, there were no significant differences between treatments (F=0.200, p=0.820, η2 =0.013) in 25(OH) concentrations suggesting no benefit of LIQ or CAP supplementation over PL. Conclusion: It appears that a chronic low dose of vitamin D in liquid or capsule form is insufficient to maintain or elevate 25(OH)D concentrations in healthy, college-aged adults. Consumers should evaluate the dosing of their multivitamins compared to current evidence-based recommendations.