A Ketone Monoester with Carbohydrate Improves Cognitive Measures Postexercise, but Not Performance in Trained Females.

PURPOSE: The acute ingestion of a ketone monoester with the coingestion of a carbohydrate (KME + CHO) compared with carbohydrate (CHO) was investigated on cycling performance and cognitive performance in trained females. METHODS: Using a two condition, placebo-controlled, double-blinded and crossover design, 12 trained females (mean ± SD: age, 23 ± 3 yr; height, 1.64 ± 0.08 m; mass, 65.2 ± 12.7 kg) completed a baseline assessment of cognitive performance (psychomotor vigilance testing (PVT), task switching, and incongruent flanker), followed by 6 × 5-min intervals at 40%, 45%, 50%, 55%, 60%, and 65% of their maximal power output (W max ) and then a 10-km time trial, concluding with the same assessments of cognitive performance. Participants consumed either 375 mg·kg -1 body mass of KME with a 6% CHO solution (1 g·min -1 of exercise) or CHO alone, across three boluses (50:25:25). RESULTS: Blood ß-hydroxybutyrate concentrations averaged 1.80 ± 0.07 and 0.13 ± 0.01 mM during exercise in KME + CHO and CHO, respectively. Blood glucose decreased after drink 1 of KME + CHO (~15%; P = 0.01) but not CHO, and lactate concentrations were lower in KME + CHO at 50%, 55%, 60%, and 65% W max (all P < 0.05) compared with CHO. Despite these changes, no differences were found between conditions for time trial finishing times (KME + CHO, 29.7 ± 5.7 min; CHO, 29.6 ± 5.7 min; P = 0.92). However, only KME + CHO resulted in increases in psychomotor vigilance testing speed (~4%; P = 0.01) and faster reaction times (~14%; P < 0.01), speed (~15%; P < 0.01), and correct responses (~13%; P = 0.03) in the incongruent flanker during posttesting compared with CHO. CONCLUSIONS: The acute ingestion of a KME + CHO elevated blood ß-hydroxybutyrate and lowered glucose and lactate across multiple time points during exercise compared with CHO. Although these changes did not affect physical performance, several markers of cognitive performance were improved by the addition of a KME in trained females.

Retrospective and Contemporary Predictors of National Collegiate Athletic Association Division I Cross-Country Performance Are Sex Specific.

ABSTRACT: Carder, MJ, Scudamore, EM, Savanna, KN, Pribyslavska, V, Bowling, LR, and O'Neal, EK. Retrospective and contemporary predictors of National Collegiate Athletic Association Division I cross-country performance are sex specific. J Strength Cond Res 37(11): 2267-2272, 2023-The purpose of this study was to identify National Collegiate Athletic Association (NCAA) Division I cross-country (XC) performance potential using laboratory-based and field-based parameters and retrospective high school (HS) personal best (PB) data at various distances of current collegiate XC runners. Fifteen female and 17 male NCAA XC runners provided their PB for 5-km (women) and 8-km (men) distances from the previous season. Bivariate correlation and stepwise and hierarchical regression modeling were used to predict XC performance. Single squat jump height and multijump reactive strength index displayed r < 0.27 for both sexes, suggesting lower-body power is a poor predictor of XC performance or masked by other factors of greater importance. Triceps skinfold thickness approached significance (r = 0.43; p = 0.09) for men but was unrelated to women's performance (r = -0.05; p = 0.86). HS XC PB neared significance (r = 0.55, p = 0.054), but no other single or combination of variables reached significance for female runners. Aerobic capacity displayed a moderate to strong relationship (r = 0.65) for male runners. High school 3,200-m PB for men produced a robust prediction capacity (r = 0.85; p = 0.005, SEE = ± 0.65 minutes), and predicted 8-km PB within 30 seconds for approximately two-thirds of runners. These outcomes suggest when recruiting HS or transfer athletes, male and female XC runners should not be recruited on the same factors. Women's XC PB is more difficult to predict, but skinfold thickness was statistically the least valuable predictor of all factors.

24 h Hydration profile of collegiate soccer players training once versus twice per day in the heat.

This study examined 24-h hydration parameters among collegiate, male soccer players (n = 17) during twice (X2) and once (X1) per day practice schedules in the heat. Urine specific gravity (USG) and body mass were measured before morning practices, afternoon practice (X2)/team meeting (X1), and the next morning practices. Fluid intake, sweat losses, and urinary losses were assessed during each 24-h window. Pre-practice body mass or USG did not differ among the timepoints. Sweat losses differed among all practices (p < 0.05) and averaged approximately 2.181±0.693 (X2AM) 1.710±0.474 (X2PM), and 3.361±0.956 L (X1AM), but players averaged replacing >50% of sweat losses with fluid intake every practice. Fluid intake during and between practices from practice 1 to the afternoon practice for X2 resulted in a positive fluid balance for X2 (+0.446±0.916 L). However, higher sweat loss during the initial morning practice and lower relative fluid intake prior to the afternoon team meeting the following morning resulted in a negative fluid balance (-0.304±0.675 L; p < 0.05: Cohen's d = 0.94) over the same time period for X1. By the start of the next morning practice sessions, both X1 (+0.664±1.051 L) and X2 (+0.446±0.916 L) were in positive fluid balance, respectively. Ample fluid consumption opportunities, scaled down practice intensities during X2, and potentially intentional greater relative fluid intake during X2 training resulted in no difference in fluid shift versus an X1 schedule before the start of practices. The majority of players maintained fluid balance drinking ad libitum regardless of practice schedule.

Seven-Week Accommodating Resistance Training Improves Wingate Peak Power But Not Muscular Strength or Endurance in Strength-Trained Females.

ABSTRACT: Parten, AL, Barker, GA, O'Neal, EK, and Waldman, HS. Seven-week accommodating resistance training improves Wingate peak power but not muscular strength or endurance in strength-trained females. J Strength Cond Res 37(9): 1789-1794, 2023-Accommodating resistance (AR) is a training technique that includes attaching elastic bands or chains to a loaded barbell to alter the resistance profile throughout the barbell movement. This study was the first to quantify the effects of AR versus a traditional resistance (TR) training program on changes in strength and power profiles in a trained female cohort. Resistance-trained (training history: 2.4 ± 1.4 years) females (age: 22.1 ± 3.0 years) completed baseline and postintervention tasks which included 1 repetition maximum (1RM) testing in the back squat (BS) and bench press (BP), a repetitions to failure in the BP (60% of 1RM), and 1 30-s Wingate test. After baseline testing, subjects were stratified (based on relative strength) into either the AR ( n = 9) or TR ( n = 10) group and then completed a supervised, 7-week training intervention. Both groups improved their 1RM in both lifts, but no statistical differences were found between groups in 1RM for BS, BP, or BP to failure ( p > 0.05). However, the AR group increased Wingate peak power (837 ± 221 to 901 ± 215 W; p = 0.04), whereas TR (868 ± 244 to 8,343 ± 182 W; p = 0.47) did not. This study supports AR with lighter relative barbell load incurs similar strength adaptations as TR. For coaches training athletes concerned with power, AR may be advantageous for improving rate of force development as demonstrated by large increases in peak Wingate power.

A Self-Selected 16:8 Time-Restricted Eating Protocol Improves Fat Oxidation Rates, Markers of Cardiometabolic Health, and 10-km Cycling Performance in Middle-Age Male Cyclists.

ABSTRACT: Witt, CR, Grozier, CD, Killen, LG, Renfroe, LG, O'Neal, EK, and Waldman, HS. A self-selected 16:8 time-restricted eating protocol improves fat oxidation rates, markers of cardiometabolic health, and 10-km cycling performance in middle-age male cyclists. J Strength Cond Res 37(5): 1117-1123, 2023-The purpose of this study was to assess the impact of 4 weeks, 16:8 time restricted eating (TRE) on markers of metabolic health and 10-km time trial (TT) performance in middle-age male cyclists. Subjects ( n = 12; age, 40-60 years; V̇ o2 peak, 41.8 ± 5.6 ml·kg -1 ·min -1 ) consisting of individuals following a habitual Western diet completed a familiarization and 2 experimental trials [PRE] and [POST]. Following habitual Western diet without TRE, anthropometric measures were assessed, followed by completion of a graded exercise test and 10-km TT. Subjects then adhered to a 4-week TRE protocol where all calories had to be consumed within a self-selected 8-hour window and then returned for repeat testing. Although self-reported caloric intake did not statistically change PRE to POST, body mass (PRE, 83.2 ± 13.4 vs. POST, 80.7 ± 12.6 kg), fat mass (∼2.5 kg), and blood pressure (systolic, 8 mm Hg; diastolic, 4 mm Hg) were all significantly lower POST (all p < 0.05), with no changes in fat-free mass. Furthermore, fat oxidation significantly increased (PRE, 0.36 ± 0.03 vs. POST, 0.42 ± 0.03 g·min -1 ; p = 0.04) following the TRE intervention and 10-km TT performance improved by ∼2 minutes POST (PRE, 29.7 ± 7.3 vs. POST, 27.4 ± 5.5 minutes; p = 0.02). Overall, our data demonstrated that middle-age male cyclists adhering to a 4-week TRE protocol can improve their body composition profile and 10-km TT performance without detriments to fat-free mass.

Assessment of Metabolic Flexibility by Substrate Oxidation Responses and Blood Lactate in Women Expressing Varying Levels of Aerobic Fitness and Body Fat.

ABSTRACT: Waldman, HS, Bryant, AR, Knight, SN, Killen, LG, Davis, BA, Robinson, MA, and O'Neal, EK. Assessment of metabolic flexibility by substrate oxidation responses and blood lactate in women expressing varying levels of aerobic fitness and body fat. J Strength Cond Res 37(3): 581-588, 2023-Collection of substrate oxidation responses during exercise is proposed as a noninvasive means for assessing metabolic flexibility in male subjects. However, because of hormonal and metabolic differences between sexes, this method may not be applicable to female subjects. This study assessed metabolic flexibility through indirect calorimetry across female subjects with different maximal oxidative capacities. Thirty-eight (18-45 years) eumenorrheic female subjects were stratified ( p < 0.05) based on V̇ o2 peak (mL·kg -1 ·min -1 ) into (1) endurance-trained (ET, n = 12, 42.6 ± 5.3), (2) recreationally active (RA, n = 13, 32.3 ± 1.6), or (3) overweight female subjects (OW, n = 13, 21.0 ± 4.0). Subjects completed the same 5-stage graded exercise test with intensities of 30, 45, 60, 75, and 90 W. Lactate [La - ], carbohydrate (CHOox), and fat (FATox) oxidation rates were assessed during the last min of each 5-minute stage. Subjects then cycled to exhaustion to determine V̇ o2 peak. Endurance-trained and RA female subjects expressed significantly ( p ≤ 0.05) higher absolute rates and rates scaled to fat-free mass of CHOox and FATox compared with OW female subjects during multiple stages. [La - ] failed to consistently differentiate the 3 groups with higher [La - ] for OW only found during stage 4; however, RER differed by 0.09 units or more at each stage for OW vs. ET. It seems that RER was more sensitive to cohort characteristics than [La - ] contrasting recent findings in male cohorts. In conclusion, indirect calorimetry is a practical and noninvasive method for assessing metabolic flexibility in eumenorrheic female subjects of varying aerobic fitness levels.

Effects of 3 Weeks Yogic Breathing Techniques on Sub-maximal Running Responses.

This study investigated the influence of yoga breathing techniques (YBT) on physiological and perceptual responses during sub-maximal treadmill running. Runners (n = 21) of various fitness (VO2max 48.4 ± 9.5 ml/kg/min) were assigned to Yoga (YG) or control (CT) group before completing pre/post treadmill trials where velocity was self-selected to produce an RPE 4 and RPE 7 (10 min each). YG (n =11) practiced three styles of YBT (30 min/day, 6 days/wk) for 3 consecutive wks. Self-selected running velocity for YG improved significantly at both prescribed RPE 4 (pre 157.63 ± 26.20 M/min, post 181.02 ± 24.22 M/min, p = 0.01) and prescribed RPE 7 (pre 201.97 ± 31.28 M/min, post 222.68± 35.32 M/min, p = 0.01). VO2 at RPE 7 increased significantly (pre 42.6 ± 6.9 ml/kg/min, post 47.3 ± 6.2 ml/kg/min, p = 0.02), TV at RPE 7 (pre 1.81 ± 0.30, post 2.04 ± 0.41, p = 0.01), and MV at RPE 7 (pre 77.25 ± 12.42, post 91.23 ± 20.05, p = 0.01). The CT group showed no significant changes except for TV at RPE 7 (pre 1.9 ± 0.3, post 2.0 ± 0.3, p = 0.04). Current results suggest YBT positively influences running velocity regulation during self-selected running.

Four Weeks of Hericium erinaceus Supplementation Does Not Impact Markers of Metabolic Flexibility or Cognition.

Hericium erinaceus (HE), also known as Lion's Mane mushroom, has been found to enhance cognition and metabolic flexibility in various animal models. To date however, only four studies exist in humans and none have evaluated the effects of HE on markers of metabolic flexibility or cognitive performance. A single-blind, placebo controlled, parallel-longitudinal study was used to determine the effects of HE on markers of metabolic flexibility and cognition. Twenty-four participants completed a graded exercise test on a cycle ergometer to analyze substrate oxidation rates and markers of cardiorespiratory fitness. Additionally, two dual-task challenges consisting of a Stroop Word Challenge interspersed with a Mental Arithmetic Challenge were performed, pre-post the graded exercise test, to evaluate markers of cognition in a pre-post fatigued state. Participants were stratified into two groups, receiving either 10 g of HE per day or placebo for 4-weeks in the form of two muffins identical in taste and appearance. Repeated-measures analysis of variance were conducted to evaluate potential interactions or main effects. Although group differences were noted at baseline, there were no significant interactions or main effects observed from HE ingestion for any dependent variable (all p > 0.05). Our data suggest that ingesting 10 g of HE per day for 4-weeks had no impact on metabolic flexibility and cognition in a college-age cohort. Due to the limited research on HE supplementation, future research is needed to establish an effective supplement dose and duration for potential physiological changes to be observed in humans.

A 3-Week, Low-Carbohydrate, High-Fat Diet Improves Multiple Serum Inflammatory Markers in Endurance-Trained Males.

ABSTRACT: Waldman, HS, Heatherly, AJ, Killen, LG, Hollingsworth, A, Koh, Y, and O'Neal, EK. A three-week, low-carbohydrate, high-fat diet improves multiple serum inflammatory markers in endurance-trained males. J Strength Cond Res 36(9): 2502-2508, 2022-This study examined the effects of a low-carbohydrate, high-fat diet (LCHF) on inflammatory marker responses in middle-aged endurance athletes. Eight male runners maintained their habitual mixed diet (HMD) in the first phase of the study before switching to a noncalorically restricted LCHF diet (∼70% of kcals from fat; carbohydrate <50 g) for 3 weeks. Subjects completed a 50-minute fixed pace treadmill running protocol in a hot environment, followed by a 5-km outdoor time trial. Fasting serum samples were collected immediately after exercise and heat stress restriction, and again 24 hours after the exercise/heat stressor. Thirty inflammation markers were assessed using the multiplex flow immunoassay technique. Seven markers (BAFF/TNFSF-13, sCD30/TNFRSF8, sCD163, Chitinase3-like1, gp130SIL-6Rß, sTNFR-1, and sTNFR-2) reached statistical significance ( p < 0.05) favoring LCHF before exercise, and sCD30/TNFRSF8 favored ( p < 0.05) LCHF before (HMD = 459 ± 111; LCHF = 296 ± 100) and after (HMD = 385 ± 104; LCHF = 285 ± 104 pg·ml -1 ) exercise. Although the current dietary intervention was short in duration, LCHF seems to offer some protection against multiple chronic inflammation markers for physically active men between ages 30 and 50 years.

Effects of 2.4 kg of Proximal External Loading on 5-km Running Performance.

ABSTRACT: Sharp, DW, Swain, JC, Boy, TG, Killen, LG, Green, JM, and O'Neal, EK. Effects of 2.4 kg of proximal external loading on 5-km running performance. J Strength Cond Res 36(7): 1833-1838, 2022-Racing weight is a popular topic in the running community. This study examined effects of modest loading via a ∼2.4-kg soft and malleable weighted compression garment on overground running performance. Former and current collegiate cross-country runners (5 women and 6 men) completed 2 outdoor, solo road course runs 7 days apart on a familiar training route. During the first run (CON) subjects ran as closely as possible to their goal pace for a "hard speed day" workout based on predetermined paces according to current training level. During a subsequent run, subjects attempted to match their pace with aid from global positioning system watches and splits verbally announced on the course while wearing the weighted compression garment (LOAD). Metabolic data was later assessed during 5-minute running bouts on a treadmill with CON and LOAD conditions at subject's CON run pace. LOAD was slower (p < 0.01) at the 1.6-km mark (6:03 ± 0:37 vs. 6:13 ± 0:40) and finish (18:29 ± 2:06 vs. 19:15 ± 2:16). There was no differentiation (p > 0.05) between V̇o2 (CON 3.47 ± 0.86; LOAD 3.56 ± 0.77 L·min-1) or respiratory exchange ratio (CON 1.05 ± 0.06; LOAD 1.06 ± 0.04) during the 5-minute running economy bouts. There was an inverse (r = -0.42) but nonsignificant (p = 0.22) relationship between percent difference in body mass and percent difference in performance. Metabolic variable differentiation was not detectable at race pace, but 2.4 kg of proximal loading resulted in an approximately 4% acute performance impairment.

Effects of Magnesium Supplementation on Muscle Soreness and Performance.

ABSTRACT: Reno, AM, Green, M, Killen, LG, O'Neal, EK, Pritchett, K, and Hanson, Z. Effects of magnesium supplementation on muscle soreness and performance. J Strength Cond Res 36(8): 2198-2203, 2022-This double-blind, between-group study examined effects of magnesium (Mg) supplementation (350 mg·d -1 , 10 days) on muscle soreness and performance. College-aged male ( n = 9) and female ( n = 13) subjects completed baseline and posttreatment eccentric bench press sessions inducing fatigue/soreness followed by performance sessions (total volume and repetitions to failure [RTF] [65, 75, and 85% of 1 repetition maximum]) 48 hours later with perceptual measures. Subjects estimated soreness using a Delayed Onset of Muscle Soreness scale by striking a vertical line on a 6-cm horizontal line (at 24, 36, and 48 hours post trial) from 0-no soreness to 6-intolerable soreness. Results are presented as means ± SD (alpha ≤0.05). Mg significantly reduced (∼1-2 units lower on a 6-point scale) muscle soreness from the baseline eccentric to postintervention trial 24, 36, and 48 hours with no significant change for placebo (Pla) group. Performance approached significance for total RTF ( p = 0.06) and 65 and 75% RTF ( p = 0.08) (Mg vs. Pla). Perceptual responses for session rating of perceived exertion and acute rating of perceived exertion were significant for Mg (5.1 ± 2.4 to 4.1 ± 2.0) vs. Pla (5.0 ± 1.8 to 5.5 ± 1.6). Perceived recovery after supplementation was improved vs. baseline for Mg (5.4 ± 2.2 to 7.5 ± 2.3) but not for Pla (6.2 ± 2.4 to 7.2 ± 3.3). Results show significantly reduced muscle soreness, session rating of perceived exertion, acute rating of perceived exertion, and improved perceived recovery after Mg (vs. Pla) supplementation and some evidence for positive performance impact.

The Cardiometabolic Health Benefits of Sauna Exposure in Individuals with High-Stress Occupations. A Mechanistic Review.

Components of the metabolic syndrome (i.e., hypertension, insulin resistance, obesity, atherosclerosis) are a leading cause of death in the United States and result in low-grade chronic inflammation, excessive oxidative stress, and the eventual development of cardiometabolic diseases (CMD). High-stress occupations (HSO: firefighters, police, military personnel, first responders, etc.) increase the risk of developing CMD because they expose individuals to chronic and multiple stressors (i.e., sleep deprivation, poor nutrition habits, lack of physical activity, psychological stress). Interestingly, heat exposure and, more specifically, sauna bathing have been shown to improve multiple markers of CMD, potentially acting as hormetic stressors, at the cellular level and in the whole organism. Therefore, sauna bathing might be a practical and alternative intervention for disease prevention for individuals with HSO. The purpose of this review is to detail the mechanisms and pathways involved in the response to both acute and chronic sauna bathing and collectively present sauna bathing as a potential treatment, in addition to current standard of care, for mitigating CMD to both clinicians and individuals serving in HSO.

Caffeinated Gum Does Not Influence RPE-Regulated Cadence in Recreationally-Active College Females Regardless of Habitual Caffeine Consumption.

Caffeine (CAF) has been extensively studied for its ergogenic and analgesic effects during exercise. However, the majority of these studies have been conducted in male populations. This study investigated the effects of acute CAF chewing gum on self-selected exercise intensity during a rating of perceived exertion (RPE) production trial in active females (n = 16, 21.0 ± 2.8 y). Data were also analyzed based on habitual CAF consumption level. Participants completed a V̇O2peak trial, followed by a familiarization and two randomized, triple-blinded experimental RPE production trials on an arm ergometer [clamped resistance, blinded to self-selected cadence (CAD)] with either CAF gum (300 mg; 4.8 ± 0.7 mg/kg-1 body mass) or placebo (PLA), at a prescribed RPE of 4 and 7 (10 min each). Self-selected CAD did not statistically differ (p > 0.05) between CAF or PLA for an RPE4 (37.7 ± 1.6 vs. 37.6 ± 1.6 rev·min-1) or RPE7 (42.9 ± 1.6 vs. 41.2 ± 1.7 rev·min-1), respectively. There were no statistical differences between treatment groups for any other variables, except restlessness rating which was significantly higher (3.5 vs. 2.2; p = 0.03, d = 0.64) for the CAF group compared to PLA. Secondary analysis revealed no statistical differences for any variables between habitual consumers of low (23 ± 20 mg/day) or mod/high (195 ± 93 mg/day) CAF. Our data support previous studies examining CAF in women across different testing modalities and suggest that regardless of habitual CAF consumption, females might require higher doses of CAF to replicate subjective and physiological responses commonly observed using similar RPE production protocols in male participants. These findings support the need for additional investigations into female physiological and perceptual responses following CAF ingestion.

Effects of Three Modest Levels of Proximal Loading on Marathon Pace Running Economy.

This study examined the effect of modest increases in proximal body mass on running economy expressed as metabolic cost (MC). External loads of 1.6 (L), 2.4 (M), and 3.2 kg (H) were added to the anterior and posterior torso region of male (n = 18) and female (n = 18) runners using a double-layered compression garment with gel inserts. MC was evaluated using stoichiometry equations of data collected via indirect calorimetry. Data was collected during four, 5-min running bouts at marathon pace for the 3 load levels and an unloaded state (CON). When data from both sexes were combined, MC for CON (13.2 ± 2.7) was lower (p < 0.05) versus L (13.5 ± 2.6), M (13.6 ± 2.6), and H (13.7 ± 2.6 kcal/min), but L did not differ from CON when data was analyzed for each sex. Male runners exhibited stepped increases in MC across loads and a weak-moderate relationship (r = 0.37; p < 0.01) between percentage change in absolute MC and increased percent body mass. A prediction model for MC (Δ% kcal/min = 0.98(Δ% body mass) - 0.91; SEE = ± 2.5%) was developed. For female runners, L increased MC by ~3.5% above CON, but no differentiation was found among L, M, and H, limiting the development of a prediction equation for females. Modest increases in body mass can produce detectable and potentially important levels of running economy impairment, but the relationship between changes in body mass and RE are complex, particularly in regards to sex.

Effects of 3 Weeks Yogic Breathing Practice on Ventilation and Running Economy.

Yogic breathing techniques (Pranayama) positively impact respiratory function (RF) in non-endurance trained individuals. The purpose of this study investigated effects of routine Pranayama practice on RF, running economy (RE) and perceptual responses. A between subject's case-control study design was incorporated. Eleven runners practiced three styles of Pranayama (30 min/day 6 days/week) for 3 consecutive weeks (YG) and completed a VO2 max tests on a treadmill (trial 1), basic RF tests, and constant workload RE trials at 60, 70, and 80% VO2 max (trial 2 and 3). A control group (n = 10) (CT) completed the same pre - post testing without intervention. Pre vs. post values for resting forced vital capacity (FVC), peak expiratory flow rate (PEFR) and forced expiratory flow volume in one second (FEV1). Yoga improved FVC and FEV1, but did not significantly impact RE However, RPE-L for HIGH had an interaction (p < 0.05) showing a decrease for YG and an increase for CT. The current study suggests 3 weeks of yogic Pranayama fails to significantly impact RE, however some evidence indicates YG may positively alter perceptual responses at individually prescribed workloads. More work is needed to definitively establish benefits of YG for runners.

Effects of Weighted Vest Loading During Daily Living Activities on Countermovement Jump and Sprint Performance.

PURPOSE: Wearing a weighted vest (WV) during daily living and training can enhance jump and sprint performance; however, studies examining the efficacy of this method in female populations is limited. This study examined the effect of wearing a WV during daily living and training on countermovement jump (CMJ), change-of-direction, and sprint performance. METHODS: Trained females were separated into intervention (n = 9) and control (n = 10) groups. The intervention group wore WVs of ∼8% body mass 4 days per week for 8 hours per day (32 h/wk total), and 3 training sessions per week for the first 3 weeks. Subsequently, 3 weeks of regular training without WV stimulus was completed. The control group received no intervention and continued normal training for 6 weeks. Average and best performance was assessed on the single CMJ, four continuous CMJ, t-test change-of-direction drill, and a 25-m sprint at baseline, week 3, and week 6. RESULTS: No significant interactions or group effects were found. However, significant time main effects revealed increases in average rate of force development during the CMJ from baseline to week 3 (P = .048) and week 6 (P = .013), whereas peak vertical ground reaction force increased during the four continuous CMJ from baseline to week 3 (P = .048) and week 6 (P = .025) for both groups. CONCLUSIONS: The lower relative WV load used in this study failed to elicit significant improvements in jump and sprint performance in comparison with routine training, or that which have been found in past investigations with elite male athletes completing high-intensity performance tasks with greater WV loads.

Effects of Caffeine on Tennis Serve Accuracy.

This study examined the effects of caffeine on tennis serve accuracy. Division II tennis athletes (n = 10) completed two serve trials (double-blind, counterbalanced) following ingestion of 6 mg/kg of caffeine or matched placebo an hour prior to data collection. During each tennis serve trial, participants completed 48 non-fault serves divided into 3 sets with 2 serves per 8 different targets. Following each 2 serves per target format, participants completed a shuttle run sprint. Separate 2 (trial) × 8 (targets) repeated measures analysis of variances (ANOVAs) were used for distances from the target center "delta", and necessary tries for each of the 3 sets. A 2 (treatment) × 3 (set) repeated measures ANOVA was used for shuttle run times. While results were not significant, the treatment main effect approached significance (p = 0.07) in set 2 for the delta of distances when comparing caffeine (96.2 cm ± 19.8) versus placebo (107.1 cm ± 16.3). While there was no significance in sprint times, each sprint was consistently faster following caffeine consumption. Post-trial surveys revealed subjective responses approached significance with greater feelings of stomach distress (p = 0.08) and nervousness (p = 0.13) following caffeine and elevated feeling of fatigue (p = 0.19) following placebo. Therefore, with no impairment in serve accuracy coupled with some evidence of reduced fatigue, results suggest caffeine may benefit tennis athletes. Extending the understanding of the effects of caffeine on tennis serve accuracy and performance could benefit overall match performance, with the potential of improving the match outcome in extended playtime.

Effects of a 3-week High-Fat-Low-Carbohydrate Diet on Lipid and Glucose Profiles in Experienced, Middle-age Male Runners.

This study examined glucose and lipid marker responses following a 3-week, ad libitum low-carbohydrate-high-fat diet (LCHF; ~70% kcals from fat, <50 g/day of net carbohydrates) versus the habitual mixed macronutrient diet (HMD) of eight middle-age, trained male runners (40 ± 10 years; V̇O2peak = 49 ± 4 mL·kg-1·min-1). Blood was drawn at 0600 from an antecubital vein after an overnight fast under conditions of no exercise/heat stress (NEXH; 48 h of restriction from intense exercise) or 24-h after exercise/heat stress (EXH; 60 min run in hot conditions plus 5-km time trial) for both dietary conditions. Glucose improvement during LCHF approached but did not reach statistical significance (p = 0.07). Pre-exercise triacylglycerol did not differ between treatments but decreased > 20 mg/dL (p < 0.05) for both treatments from NEXH to EXH (HMD = 42 ± 16; LCHF = 35 ± 21 mg/dL). Main effects for diet were exhibited for HDL-C during NEXH and EXH (HMD = 48 ± 10 and 50 ± 11; LCHF = 57 ± 13 and 60 ± 13 mg/dL), and LDL-C also increased (p = 0.02) by ~20 mg/dL for LCHF at both collection points resulting in ~30 mg/dL greater total cholesterol for LCHF before and 24-h after exercise (p < 0.05). A 3-week, ad libitum LCHF did not elicit significant negative cardiovascular disease risk in male runners 30-50 years of age with healthy pre-intervention lipid and glucose marker status.

No Performance or Affective Advantage of Drinking versus Rinsing with Water during a 15-km Running Session in Female Runners.

The advantage of ingesting fluids during endurance exercise lasting < 90 min has recently been challenged, but literature confirming or disputing this case is limited, particularly for female athletes. This study examined the effects of consuming water versus mouth rinsing with water during a running time trial. Recreationally active female runners (n = 19) completed two, 15-km time trials on an outdoor course in temperate environment (~20ºC; 87% RH) separated by at least one week in a randomized cross-over study design. Participants consumed 355 ml of water (DW) during their run or mouth rinsed (MR) with water from a handheld water bottle every 3 km for 5 s with physiological, perceptual, and affective variables assessed. DW or MR did not affect completion time (79.8 ± 8.1 min and 79.2 ± 8.2 min, p = 0.23), HR (p = 0.35), or RPE (p = 0.73), respectively. Sweat losses were greater (p = 0.03) for DW: 1.47 ± 0.34 L compared to MR: 1.28 ± 0.27 L; however, thirst sensation was not significantly different for MR: 6.7 ± 1.4 compared to DW: 6.2 ± 1.6. A significant effect was exhibited for time (p < 0.01) but not condition for Feeling Scale and Felt Arousal Scale or Energetic and Tense Arousal. Carrying only one smaller fluid container for MR versus a larger or multiple water bottles/backpack systems used for water consumption can reduce fluid load carried during extended duration runs without altering performance or affect for runs of 1.0-1.5 h. MR may also be beneficial to decrease thirst without ingesting fluid for runners that limit exercise fluid consumption because of gastrointestinal discomfort concerns.

Ground reaction forces during a drop vertical jump: Impact of external load training.

External load training (ELT) is a supplemental training method used to potentially improve high intensity task performance. However, biomechanical parameters such as ground reaction forces (GRF), ground contact time, and time to peak GRF during a drop vertical jump (DVJ) following an ELT intervention have yet to be examined. Therefore, this study investigated the impact of ELT on certain biomechanical parameters of a DVJ task. Well-trained females stratified into two groups (ELT = 9, Control = 10) completed a DVJ from a 45.72 cm box onto a force platform at baseline, post-ELT, and post-detraining (DET). ELT consisted of wearing weight vests (WV) with 8% body mass for 32 h/week during daily living and 3 training sessions/week for 3 weeks. After ELT, a 3 week DET phase was completed. The control group replicated procedures without ELT intervention. The vertical, medial/lateral, and anterior/posterior components of the GRF were assessed during the initial contact, minimum force following initial contact, push-off, and second landing periods. Dependent variables were analyzed using a 2 (group) × 3 (time) mixed model ANOVA (p < .05). Significantly greater peak vertical GRF during the initial contact period was identified for the ELT group. Significant increases in the minimum vertical GRF following the initial contact period from baseline to post-ELT following the were observed for the ELT group, while significant increases in peak vertical GRF during the second landing period at post-ELT and post-DET in comparison to baseline was observed for both groups. The combination of greater vertical GRF during the initial contact period and the period following initial contact suggests that ELT may increase GRFs during a DVJ in comparison to routine training without a weighted vest.