Showing papers by "Eric T. Trexler published in 2017"
TL;DR: The prediction of BV from DEXA simplifies the acquisition of 4C body composition by eliminating the need for an additional BV assessment.
69 citations
TL;DR: Results indicate that well-trained collegiate football players at high levels of competition can achieve favorable changes in body composition, even late in the career, which may confer benefits for performance and injury prevention.
Abstract: Trexler, ET, Smith-Ryan, AE, Mann, JB, Ivey, PA, Hirsch, KR, and Mock, MG. Longitudinal body composition changes in NCAA Division I college football players. J Strength Cond Res 31(1): 1-8, 2017-Many athletes seek to optimize body composition to fit the physical demands of their sport. American football requires a unique combination of size, speed, and power. The purpose of the current study was to evaluate longitudinal changes in body composition in Division I collegiate football players. For 57 players (mean ± SD, age = 19.5 ± 0.9 years, height = 186.9 ± 5.7 cm, weight = 107.7 ± 19.1 kg), body composition was assessed via dual-energy x-ray absorptiometry in the off-season (March-Pre), end of off-season (May), mid-July (Pre-Season), and the following March (March-Post). Outcome variables included weight, body fat percentage (BF%), fat mass, lean mass (LM), android and gynoid (GYN) fat, bone mineral content (BMC), and bone mineral density (BMD). For a subset of athletes (n = 13 out of 57), changes over a 4-year playing career were evaluated with measurements taken every March. Throughout a single year, favorable changes were observed for BF% (Δ = -1.3 ± 2.5%), LM (Δ = 2.8 ± 2.8 kg), GYN (Δ = -1.5 ± 3.0%), BMC (Δ = 0.06 ± 0.14 kg), and BMD (Δ = 0.015 ± 0.027 g·cm, all p ≤ 0.05). Across 4 years, weight increased significantly (Δ = 6.6 ± 4.1 kg) and favorable changes were observed for LM (Δ = 4.3 ± 3.0 kg), BMC (Δ = 0.18 ± 0.17 kg), and BMD (Δ = 0.033 ± 0.039 g·cm, all p ≤ 0.05). Similar patterns in body composition changes were observed for linemen and non-linemen. Results indicate that well-trained collegiate football players at high levels of competition can achieve favorable changes in body composition, even late in the career, which may confer benefits for performance and injury prevention.
34 citations
TL;DR: Acute PE supplementation enhanced vessel diameter and blood flow, suggesting possible exercise performance enhancement from increased delivery of substrates and oxygen.
Abstract: The effects of pomegranate extract (PE) supplementation were evaluated on high-intensity exercise performance, blood flow, vessel diameter, oxygen saturation (SPO2), heart rate (HR), and blood pressure (BP). In a randomized, crossover design, nineteen recreationally resistance-trained participants were randomly assigned to PE (1000 mg) or placebo (PL), which were consumed 30 min prior to a repeated sprint ability (RSA) test and repetitions to fatigue (RTF) on bench and leg press. The RSA consisted of ten six-second sprints on a friction-loaded cycle ergometer with 30 s recovery. Brachial artery blood flow and vessel diameter were assessed by ultrasound. Blood flow, vessel diameter, SPO2, HR, and BP were assessed at baseline, 30 min post ingestion, immediately post exercise (IPost), and 30 min post exercise (30minPost). With PE, blood flow significantly increased IPost RSA (mean difference = 18.49 mL min−1; P < .05), and IPost and 30minPost RTF (P < .05) according to confidence intervals (CI). Vess...
32 citations
TL;DR: In this paper, the authors evaluated changes in body composition and muscle characteristics over a competitive season and identify relationships between these variables and performance in National Collegiate Athletic Association Division I swimmers and divers.
Abstract: Context: Previous researchers have indicated the importance of body composition and muscle quality in athletic performance. However, body composition and muscle-quality measures in swimmers and divers over a training season have yet to be evaluated. Objective: To identify changes in body composition and muscle characteristics over a competitive season and identify relationships between these variables and performance in National Collegiate Athletic Association Division I swimmers and divers. Design: Cross-sectional study. Setting: University laboratory. Patients or Other Participants: A total of 17 collegiate swimmers and divers (age = 18.6 ± 0.7 years, height = 175.8 ± 4.0 cm, body mass = 69.7 ± 7.0 kg). Main Outcome Measure(s): At preseason and postseason, body composition in each participant was assessed using dual-energy x-ray absorptiometry. Echo intensity and muscle cross-sectional area were determined from an ultrasound panoramic scan of the vastus lateralis muscle. Race times were obtained from th...
27 citations
TL;DR: Cont contest preparation may yield transient, unfavorable changes in endocrine profile, power output, RMR, and subjective sleep outcomes, and research with larger samples must identify strategies that minimize unfavorable adaptations and facilitate recovery following competition.
Abstract: Extreme body composition demands of competitive bodybuilding have been associated with unfavorable physiological changes, including alterations in metabolic rate and endocrine profile. The current case study evaluated the effects of contest preparation (8 months), followed by recovery (5 months), on a competitive drug-free male bodybuilder over 13 months (M1-M13). Serum testosterone, triiodothyronine (T3), thyroxine (T4), cortisol, leptin, and ghrelin were measured throughout the study. Body composition (BodPod, dualenergy x-ray absorptiometry [DXA]), anaerobic power (Wingate test), and resting metabolic rate (RMR) were assessed monthly. Sleep was assessed monthly via the Pittsburgh Sleep Quality Index (PSQI) and actigraphy. From M1 to M8, testosterone (623-173 ng∙dL-1), T3 (123-40 ng∙dL-1), and T4 (5.8-4.1 mg∙dL-1) decreased, while cortisol (25.2-26.5 mg∙dL-1) and ghrelin (383-822 pg∙mL-1) increased. The participant lost 9.1 kg before competition as typical energy intake dropped from 3,860 to 1,724 kcal∙day-1; BodPod estimates of body fat percentage were 13.4% at M1, 9.6% at M8, and 14.9% at M13; DXA estimates were 13.8%, 5.1%, and 13.8%, respectively. Peak anaerobic power (753.0 to 536.5 Watts) and RMR (107.2% of predicted to 81.2% of predicted) also decreased throughout preparation. Subjective sleep quality decreased from M1 to M8, but objective measures indicated minimal change. By M13, physiological changes were largely, but not entirely, reversed. Contest preparation may yield transient, unfavorable changes in endocrine profile, power output, RMR, and subjective sleep outcomes. Research with larger samples must identify strategies that minimize unfavorable adaptations and facilitate recovery following competition.
25 citations
TL;DR: Upper limit estimations for FFMI seem to vary by position; although the 97.5th percentile may represent a more suitable upper limit for the college football population as a whole, this value was exceeded by 6 linemen, with a maximal observed value of 31.7 kg·m−2.
Abstract: Fat-free mass index (FFMI) is a height-adjusted assessment of fat-free mass (FFM), with previous research suggesting a natural upper limit of 25 kg·m in resistance trained male athletes. The current study evaluated upper limits for FFMI in collegiate American football players (n = 235) and evaluated differences between positions, divisions, and age groups. The sample consisted of 2 National Collegiate Athletic Association Division I teams (n = 78, n = 69) and 1 Division II team (n = 88). Body composition was assessed via dual-energy x-ray absorptiometry and used to calculate FFMI; linear regression was used to normalize values to a height of 180 cm. Sixty-two participants (26.4%) had height-adjusted FFMI values above 25 kg·m (mean = 23.7 ± 2.1 kg·m; 97.5th percentile = 28.1 kg·m). Differences were observed among position groups (p < 0.001; η = 0.25), with highest values observed in offensive linemen (OL) and defensive linemen (DL) and lowest values observed in offensive and defensive backs. Fat-free mass index was higher in Division I teams than Division II team (24.3 ± 1.8 kg·m vs. 23.4 ± 1.8 kg·m; p < 0.001; d = 0.49). Fat-free mass index did not differ between age groups. Upper limit estimations for FFMI seem to vary by position; although the 97.5th percentile (28.1 kg·m) may represent a more suitable upper limit for the college football population as a whole, this value was exceeded by 6 linemen (3 OL and 3 DL), with a maximal observed value of 31.7 kg·m. Football practitioners may use FFMI to evaluate an individual's capacity for additional FFM accretion, suitability for a specific position, potential for switching positions, and overall recruiting assessment.
20 citations
TL;DR: RMR and male testosterone increased while FM was preferentially gained 4-6 weeks postcompetition, and RMR changes were associated with change in body fat percent, ΔBF%, ΔFM, and Δweight.
Abstract: The purpose of the current study was to evaluate changes in body composition, metabolic rate, and hormones during postcompetition recovery. Data were collected from natural physique athletes (7 male/8 female) within one week before (T1) competition, within one week after (T2), and 4-6 weeks after (T3) competition. Measures included body composition (fat mass [FM] and lean mass [LM] from ultrasongraphy), resting metabolic rate (RMR; indirect calorimetry), and salivary leptin, testosterone, cortisol, ghrelin, and insulin. Total body water (TBW; bioelectrical impedance spectroscopy) was measured at T1 and T2 in a subsample (n = 8) of athletes. Significant (p T2 > T1), LM (T1 = 57.6 ± 13.9 kg, T2 = 59.4 ± 14.2, T3 = 59.3 ± 14.2; T2 and T3 > T1), and FM (T1 = 7.7 ± 4.4 kg, T2 = 8.0 ± 4.4, T3 = 10.0 ± 6.2; T3 > T1 and T2). TBW increased from T1 to T2 (Δ=1.9 ± 1.3 L, p < .01). RMR increased from baseline (1612 ± 266 kcal/day; 92.0% of predicted) to T2 (1881 ± 329, 105.3%; p < .01) and T3 (1778 ± 257, 99.6%; p < .001). Cortisol was higher (p < .05) at T2 (0.41 ± 0.31 μg/dL) than T1 (0.34 ± 0.31) and T3 (0.35 ± 0.27). Male testosterone at T3 (186.6 ± 41.3 pg/mL) was greater than T2 (148.0 ± 44.6, p = .04). RMR changes were associated (p ≤ .05) with change in body fat percent (ΔBF%; r = .59) and T3 protein intake (r= .60); male testosterone changes were inversely associated (p≤ .05) with ΔBF%, ΔFM, and Δweight (r=-0.81--0.88). TBW increased within days of competition. Precompetition RMR suppression appeared to be variable and markedly reversed by overfeeding, and reverted toward normal levels following competition. RMR and male testosterone increased while FM was preferentially gained 4-6 weeks postcompetition.
19 citations
TL;DR: Segmental evaluation of body composition, specifically in the lower extremities and abdomen, may be an effective and efficient way to evaluate metabolic status.
Abstract: Low resting metabolic rate (RMR) and high carbohydrate reliance at rest are associated with weight gain, but are highly variable in obese individuals. This study determined the relationship of total and segmental body composition and adiposity hormones with RMR and respiratory exchange ratio (RER) in overweight and obese adults. In 49 men (n = 23) and premenopausal women (n = 26) [mean ± SD; age = 35.0 ± 8.9 years; body mass index (BMI) = 33.6 ± 5.2 kg·m−2; percent body fat (%fat) = 40.0 ± 8.0%], RMR and RER were evaluated using indirect calorimetry. Total and segmental body composition [fat mass (FM), percent fat (%fat), lean mass (LM), visceral adipose tissue (VAT)] were estimated using dual-energy X-ray absorptiometry. Fasted blood and saliva samples were analyzed for insulin, leptin, estradiol, and cortisol. In men (M) and women (W), RMR significantly correlated (p 0.05). Segmental evaluation of body composition, specifically in the lower extremities and abdomen, may be an effective and efficient way to evaluate metabolic status. Sex-specific evaluations are also imperative.
19 citations
TL;DR: Acute supplementation with a Cordyceps militaris containing mushroom blend may improve tolerance to high-intensity exercise; greater benefits may be elicited with consistent chronic supplementation.
Abstract: To determine the effects of a mushroom blend containing Cordyceps militaris on high-intensity exercise after 1 and 3 weeks of supplementation. Twenty-eight individuals (Mean ± standard deviation [SD]; Age = 22.7 ± 4.1 yrs; Height = 175.4 ± 8.7 cm; Weight = 71.6 ± 12.0 kg) participated in this randomized, repeated measures, double-blind, placebo-controlled design. Maximal oxygen consumption (VO2max), time to exhaustion (TTE), and ventilatory threshold (VT) were measured during a maximal graded exercise test on a cycle ergometer. Relative peak power output (RPP), average power output (AvgP), and percent drop (%drop) were recorded during a 3 minute maximal cycle test with resistance at 4.5% body weight. Subjects consumed 4 g·d−1 mushroom blend (MR) or maltodextrin (PL) for 1 week. Ten volunteers supplemented for an additional 2 weeks. Exercise tests were separated by at least 48 hours and repeated following supplementation periods. One week of supplementation elicited no significant time × treatment...
11 citations
Journal Article•
TL;DR: A retrospective analysis of data from a pilot study found preliminary evidence suggesting that BAT estimation may be biased in endurance-trained individuals, which may relate to skeletal muscle FDG uptake, and proposes potential solutions that facilitate unbiased estimation of BAT activity in groups that differ in terms of lean body mass and physical activity level.
Abstract: Brown adipose tissue (BAT) in adults has been shown to have a meaningful impact on energy expenditure and cold-induced thermogenesis. Data from rodent research have suggested that exercise may be a promising method of increasing BAT activity, with potential applications to the treatment and prevention of obesity and diabetes. However, emerging human research using positron emission tomography (PET) with [18F] Fluorodeoxyglucose (FDG) has identified lower BAT activity in endurance-trained athletes compared to sedentary controls, despite similar metabolic rate responses to cold exposure. Here we report a similar incidental finding in a pilot study that included a sample of 2 endurance athletes and 10 untrained individuals. This incidental finding motivated a retrospective analysis of the data aimed at assessing the potential confounding influence of muscle FDG uptake on BAT estimation. Results indicated that athletes skewed the relationship between body mass index (BMI) and supraclavicular fat (sFAT) FDG uptake, while a non-significant inverse relationship between muscle FDG uptake and sFAT FDG uptake was also observed. The current retrospective analysis provides preliminary evidence suggesting that BAT estimation may be biased in endurance-trained individuals, which may relate to skeletal muscle FDG uptake. These results point to important methodological considerations for estimating BAT activity via FDG uptake, for which we propose potential solutions that facilitate unbiased estimation of BAT activity in groups that differ in terms of lean body mass and physical activity level.
8 citations
TL;DR: After controlling for relevant covariates, postretirement &Dgr;BMI was positively and independently associated with prevalence of CHD, diabetes, and HBP.
Abstract: PurposeElevated rates of cardiometabolic diseases have been observed in former American football players. The current study sought to determine whether change in body mass index (ΔBMI) after retirement influences the prevalence of CHD, diabetes, or high blood pressure (HBP) in former profess
01 Jan 2017
TL;DR: The consumption of caffeine at moderate doses by healthy adults is considered safe, with no associated side effects and some evidence of health benefits, and recent studies suggest that gene polymorphisms could account for this variability.
Abstract: Caffeine is the mostly widely consumed psychoactive drug in the world. Its ingestion (3–9 mg/kg body weight) prior to exercise seems to increases performance during prolonged endurance exercise. The effects of acute caffeine ingestion on strength and power performance are equivocal, but some studies demonstrated positive effects in well-trained athletes or recreational subjects. Caffeine was part of the list of banned substances of the International Olympic Committee, but since 2004 has been removed from this list. The ergogenic effects of caffeine demonstrate a high interindividual variability with responders and nonresponders, and recent studies suggest that gene polymorphisms could account for this variability. The consumption of caffeine at moderate doses (up to 400 mg/day) by healthy adults is considered safe, with no associated side effects and some evidence of health benefits.