Total and regional dual X-ray absorptiometry derived four-compartment model.

BACKGROUND & AIMS: Dual X-ray absorptiometry (DXA) software allows for total and regional (i.e., arms and legs) assessment of body composition, with recent advancements allowing for DXA derived volume. The use of DXA derived volume allows for the development of a convenient four-compartment model to accurately measure body composition. The purpose of the current study is to evaluate the validity of a regional DXA derived four-compartment model. METHODS: A total of 30 males and females underwent one whole body DXA scan, underwater weighing, total and regional bioelectrical impedance spectroscopy, and regional measures of water displacement. Manually created region of interest boxes assessed regional DXA body composition. Linear regression models with fat mass from the DXA as the dependent variable and body volume from water displacement, total body water from bioelectrical impedance spectroscopy, and DXA bone mineral and body mass as independent variables created regional four-compartment models. Measures of fat-free mass and percent fat were calculated using the four-compartment derived fat mass. T-tests assessed DXA derived four-compartment model to the traditional four-compartment model with volume assessed by water displacement. Regression models were cross-validated using the Repeated k-fold Cross Validation method. RESULTS: Arm and leg regional DXA derived four-compartment model for fat mass (p = 0.999, both arm and leg), fat-free mass (p = 0.999, both arm and leg), and percent fat (arm: p = 0.766; leg: p = 0.938) were not significantly different from the regional four-compartment model with regional volume measured via water displacement. Cross-validation of each model produced R2 values of 0.669 for the arm and 0.783 for the leg. CONCLUSIONS: The DXA can be used to create four-compartment model for estimating total and regional fat mass, fat-free mass, and percent fat. Therefore, these results allow for a convenient regional four-compartment model with DXA derived regional volume.

Dual X-ray absorptiometry-derived total and regional body volume.

BACKGROUND & AIMS: Although dual X-ray absorptiometry (DXA) has been used to determine total body volume, using DXA to determine regional (i.e., arm and leg) volumes needs further assessment. Thus, the aim of the present study is to evaluate the validity of total and regional DXA-derived body volume compared to a traditional method for measuring body volume. METHODS: A total of 30 males and females (Age: 25.9 ± 4.0 yrs; Height: 1.75 ± 0.10 m; Weight: 70.98 ± 14.02 kg) underwent one whole body DXA scan, underwater weighing, and regional measures of volume via water displacement. Manually created DXA region of interest boxes were used to determine regional DXA body composition. Total body volume was calculated by taking the participant's dry weight and dividing it by the average density from underwater weighing. Linear regression models with body volume from underwater weighing for total body volume and water displacement for regional volume as the dependent variable and DXA lean mass, fat mass, and bone mass as independent variables created total and regional DXA-derived body volume. T-tests assessed DXA-derived body volume to the traditional method of body volume assessment. Regression models were cross-validated using the Repeated k-fold Cross Validation method. RESULTS: DXA-derived total body volume was not significantly (p = 0.999) different from total body volume measured via total body water displacement. In addition, both arm and leg regional DXA-derived volume was not significantly different (p = 0.999) compared to regional volume measured by regional water displacement. Cross-validation of each model produced R2 values of 0.992, 0.923, and 0.932 for total body, arm, and leg, respectively. CONCLUSIONS: The DXA may be used as valid method for estimating total and regional body volume. Thus, these results expand the DXA's capabilities and potentially allow for a convenient regional four-compartment model with DXA-derived regional volume.

No Changes in Body Composition in NCAA Division I Collegiate Football Players because of COVID-19 Restrictions.

ABSTRACT: Czeck, MA, Roelofs, EJ, Evanoff, NG, and Dengel, DR. No Changes in body composition in NCAA Division I Collegiate Football Players due to COVID-19 restrictions. J Strength Cond Res 36(6): 1749-1752, 2022-The purpose of this study was to explore the impact of coronavirus disease 2019 (COVID-19) restrictions on body composition, assessed by dual x-ray absorptiometry (DXA), between the 2020 postseason (pre-COVID-19 restrictions) and the 2021 postseason (post-COVID-19 restrictions) in collegiate football players (n = 50). In addition, a subset of athletes (n = 23) was used to explore body composition variables across 4 postseason time points. Body composition variables assessed were total and regional body fat percent, total mass, lean mass, fat mass, bone mineral content, bone mineral density, and visceral adipose tissue mass. Paired t-tests were used to determine differences between the 2020 postseason and the 2021 postseason in body composition variables. Analysis of variance with Tukey HSD post hoc tests assessed significant differences in total and regional body composition across 4 years while adjusting for multiple comparisons. There were no significant differences (p > 0.05) between postseason 2020 and postseason 2021 for all measures of body composition. In a subset of athletes, body composition was analyzed over a 4-year period of time. There were no significant differences between all 4 time points for all measures of body composition. In conclusion, body composition variables in this study's subjects were not affected because of coronavirus disease 2019 restrictions or over 4 years of their collegiate football career.

The role of FSH in body composition in hematopoietic cell transplant recipients.

BACKGROUND: Childhood cancer survivors who received a hematopoietic cell transplantation (HCT) are at increased risk for follicle-stimulating hormone (FSH) abnormalities, which may have a significant negative impact on bone health and body composition. This study's purpose was to examine FSH and body composition in HCT recipients, non-HCT recipients and healthy controls. METHODS: The study included HCT recipients (n = 24), non-HCT recipients (n = 309), and a control group of healthy siblings (n = 211) all aged 9-18 years. A fasting blood sample was collected to measure FSH. All participants underwent a dual X-ray absorptiometry scan to assess total and regional percent fat, lean mass (LM), fat mass (FM), bone mineral content (BMC), bone mineral density (BMD), and visceral adipose tissue (VAT) mass. RESULTS: FSH was significantly higher in HCT recipients compared to non-HCT recipients and healthy controls. HCT recipients had significantly lower total body weight, total LM, arm and leg LM, BMC and BMD compared to non-HCT recipients and healthy controls (p < .05). Non-HCT recipients had significantly higher total, trunk, android, gynoid, arm and leg FM compared to healthy controls. Also, healthy controls had significantly lower VAT mass compared to non-HCT recipients. CONCLUSIONS: This study's results show that HCT recipients have significant reductions in BMD, worse body composition, and abnormal FSH levels compared to non-HCT recipients and healthy controls.

Body Composition and On-Ice Skate Times for National Collegiate Athletic Association Division I Collegiate Male and Female Ice Hockey Athletes.

ABSTRACT: Czeck, MA, Roelofs, EJ, Dietz, C, Bosch, TA, and Dengel, DR. Body composition and on-ice skate times for NCAA Division I collegiate male and female ice hockey athletes. J Strength Cond Res 36(1): 187-192, 2022-This study's purpose was to explore positional differences for an on-ice timed skate test and its relationship to body composition. Male (n = 15) and female (n = 18) collegiate hockey players participated in this study (total n = 33). Each player was categorized by position of forward or defensemen. Dual x-ray absorptiometry assessed total body composition variables of lean, fat, and bone mass as well as regional measures of lean mass, fat mass, and visceral adipose tissue. Total time and section times were determined for the on-ice skating test through a gated automatic timing system at 9, 18, 24, 42, 48, 66, 82, 132, and 148 m. Analysis of variance and Tukey's honest significance difference assessed on-ice skate time differences between positions (p ≤ 0.05). Correlations between body composition variables and skate times were determined for change of direction, skating time, linear skate time, and total skate time. There were no significant differences between positions for skate times (p > 0.05). Body fat percent (p = 0.007; r = 0.55), total fat mass (p = 0.027; r = 0.46), and leg fat mass (p = 0.019; 0.49) were significantly correlated with total skate time in men, whereas only body fat percent was significantly correlated with change of direction (p = 0.022; r = 0.54) and total skate times (p = 0.016; r = 0.56) in women. The total upper-body mass to leg lean mass ratio was significantly correlated with change of direction (p = 0.036; r = 0.50) in women. In conclusion, the results from this study suggest no differences between on-ice skating times between forwards and defensemen. However, body fat percentage was correlated with on-ice skate times in male and female collegiate hockey players.

The Role of Follicle-stimulating Hormone in Vascular Dysfunction Observed in Hematopoietic Cell Transplant Recipients.

Childhood cancer survivors who receive a hematopoietic cell transplantation (HCT) are at increased risk for follicle-stimulating hormone (FSH) abnormalities, which may have a substantial negative impact on vascular function. The purpose of this study was to examine the association of vascular function with FSH in HCT recipients, non-HCT recipients and healthy controls. The study included childhood cancer survivors who were HCT recipients (n=24) and non-HCT recipients (n=308), and a control group of healthy siblings (n=211) all between 9 and 18 years old. Vascular measures of carotid artery structure and function (compliance and distensibility), brachial artery flow-mediated dilation and endothelial-independent dilation were measured using ultrasound imaging. A fasting blood sample was collected to measure hormone levels. FSH was significantly higher in HCT recipients compared with non-HCT recipients and healthy controls (P<0.01). Carotid compliance and distensibility were significantly lower in HCT and non-HCT recipients compared with healthy controls (P<0.05). Higher FSH was associated with decreased carotid compliance (P<0.05). This study's results suggest that higher levels of FSH in HCT recipients may result in significant reductions in vascular function compared with non-HCT recipients and healthy controls. Therefore, gonadotropin endocrine dysfunction, particularly abnormal FSH levels, may be an underlying mechanism of vascular dysfunction.

Male and Female Collegiate Ice Hockey Athletes' Body Composition Over Competitive Seasons.

Eighty-three male and female (49/34) athletes underwent determination of total fat mass (FM), lean mass (LM), bone mineral density (BMD) and visceral adipose tissue (VAT) by dual X-ray absorptiometry during the pre-season, in-season and off-season. Athletes were classified by position of Goalie (G; M/F=7/6), Forward (F; M/F=26/18), or Defenseman (D; M/F=16/10). In males, all positions were similar in weight, FM, LM, BMD and VAT. In females, F weighed less than D and G. FM and VAT was lower in F than D and G, but D was not different from G. LM was lower in F compared to D, but not G, with no differences between D and G. There were no differences in BMD between positions. There were no seasonal changes in males for body composition variables. In females, FM, LM and VAT decreased from pre-season to in-season, while BMD increased. From in-season to off-season, LM increased and BMD decreased. From off-season to pre-season, FM and VAT increased. In conclusion, there were no differences across position or seasonal changes in body composition in males. However, there were positional and seasonal changes in body composition in females, indicating possible differences in training regimens during the off-season compared to males.

Post-Exercise Ingestion of Low or High Molecular Weight Glucose Polymer Solution Does Not Improve Cycle Performance in Female Athletes.

ABSTRACT: Mock, MG, Hirsch, KR, Blue, MNM, Trexler, ET, Roelofs, EJ, and Smith-Ryan, AE. Postexercise ingestion of low or high molecular weight glucose polymer solution does not improve cycle performance in female athletes. J Strength Cond Res 35(1): 124-131, 2021-The current study sought to evaluate the effects of postexercise ingestion of a high molecular weight (HMW) glucose polymer solution compared with an isocaloric low molecular weight (LMW) solution or placebo (PLA) on subsequent cycling performance in female athletes. In a randomized, double-blind, placebo-controlled, cross-over design, 10 competitive female cyclists (Mean ± SD; Age = 25.7 ± 5.0 years; V̇o2peak = 49.7 ± 4.3 ml·kg-1·min-1) completed 3 testing sessions separated by 7-10 days. Visits consisted of a ride-to-exhaustion (RTE) at 75% V̇o2peak, followed by immediate consumption of 700 ml containing either: 1.2 g·kg-1 LMW (maltodextrin/dextrose/fructose); 1.2 g·kg-1 HMW (Vitargo); or 0.066 g·kg-1 PLA (noncaloric flavoring). After 2 hours of rest, subjects performed a 15-minute time trial (TT). Respiratory exchange ratio (RER) was assessed via indirect calorimetry during exercise. Total body water (TBW) was measured using bioelectrical impedance to assess fluid balance. When covaried for estrogen, there was no treatment effect on distance (km; p = 0.632) or power output (watts; p = 0.974) during the 15-minute TT. Respiratory exchange ratio was not significantly different during the LMW and HWM TTs (p > 0.999), but both were significantly higher than PLA (p = 0.039, p = 0.001, respectively). Changes in total body water pre-exercise to postexercise were not significantly different between trials (p = 0.777). Despite benefits of HMW on cycling performance previously reported in males, current results demonstrate no ergogenic effect of HMW or LMW in females. Sex differences in substrate utilization may account for the discrepancy, and further research involving performance nutrition for female athletes is merited.

Muscle cross-sectional area and motor unit properties of the medial gastrocnemius and vastus lateralis in normal weight and overfat children.

NEW FINDINGS: What is the central question of this study? Are differences in muscle size and motor unit properties between normal weight and overfat children muscle specific? What is the main finding and its importance? Muscle cross-sectional area and motor unit action potential amplitudes and firing rates were similar between overfat and normal weight children for both the medial gastrocnemius and vastus lateralis muscles. There was no evidence that the chronic mechanical overload provided by the greater body mass resulted in significant hypertrophy of contractile tissue or motor units that would be used during lower-to-moderate intensity activities. ABSTRACT: This study examined the possible differences in muscle cross-sectional area (mCSA), motor unit action potential amplitudes (MUAPAMPS ) and interspike intervals (ISIs) of the firing instances of the medial gastrocnemius (MG) and vastus lateralis (VL) between normal weight (NW) and overfat (OF) children aged 7-10 years. Fourteen NW (age = 8.6 ± 1.1 years, BMI = 15.8 ± 1.4 kg m-2 ) and 12 OF (age = 8.8 ± 0.9 years, BMI = 21.8 ± 2.4 kg m-2 ) children performed isometric trapezoidal muscle actions at 40% of maximal voluntary contraction of the plantar flexors and knee extensors. Surface electromyography was recorded from the MG and VL and decomposed into the firing events of motor units (MUs). Statistical procedures were performed on the composite recruitment thresholds (RTs), ISIs and MUAPAMPS of recorded MUs collapsed across subjects and the y-intercepts and slopes calculated from each subject's ISI and MUAPAMP vs. RT relationships. Ultrasound was used to assess mCSA, echo intensity (mEI), and subcutaneous fat (sFAT) of the MG and VL. The OF had greater mCSAs, mEI and sFAT (P = 0.004-0.024), but there were no differences in mCSA when accounting for mEI for the MG (P = 0.506) and VL (P = 0.326). The NW children had significantly greater composite MUAPAMPS for the VL and MG (P < 0.001), but only significantly larger MUAPAMPS of the VL remained for the NW (P < 0.001) when subjects were matched for sFAT. There were no differences between groups for the ISI or MUAPAMP vs. RT relationships (P > 0.05). These findings suggest that the OF children did not undergo significant muscle or MU hypertrophy that would be routinely activated during activities of daily living.

Examination of muscle morphology and neuromuscular function in normal weight and overfat children aged 7-10 years.

Neuromuscular function in young overweight/obese (OF) children is not well described. AIM: This study examined isometric and isokinetic leg extensor strength, muscle size (mCSA) and tissue composition as measured via echo intensity (mEI), and motor unit (MU) firing rates in normal weight (NW) and OF children aged 7-10 years. METHODS: Fourteen NW (eight girls and six boys, BMI: 15.8 ± 1.4 kg/m2 ) and 15 OF (10 girls and five boys, BMI: 20.8 ± 2.3 kg/m2 ) children volunteered to perform this study. Percentage body fat (%BF) was measured, and mCSA, mEI, and subcutaneous fat (sFAT) of the vastus lateralis (VL) was assessed. MU mean firing rates (MFRs) in relation to recruitment threshold (RT) of the VL were assessed during submaximal isometric contractions. Maximal isokinetic contractions were performed at 1.05 and 4.20 rad/s. The 95% confidence intervals (CI) from the statistical tests are presented. RESULTS: The OF children had greater %BF (95% CI = -15.1 to -7.2), mCSA (95% CI = -4.1 to -1.2), mEI (95% CI = -22.3 to -5.9), and sFAT (95% CI = -0.5 to -0.1), greater rate of strength loss with increasing isokinetic velocities (95% CI = 0.4 to 5.4), and a smaller range of MFRs (95% CI = 0.007 to 7.136) at the steady torque than the NW children. CONCLUSIONS: The OF children had poorer muscle tissue composition, greater velocity-related impairments in muscle strength, and a smaller range of MFRs at the targeted torque that may suggest altered MU recruitment strategies. Interventions in OF children should include exercises and recruit higher-threshold MUs, such as high-intensity resistance exercises.

Dietary macronutrient distribution influences postexercise substrate utilization in women: a cross-sectional evaluation of metabolic flexibility.

BACKGROUND: Metabolic flexibility is the ability to alter substrate utilization in response to substrate availability, which may influence health and performance. The current study evaluated the effects of habitual macronutrient distribution on energy expenditure (EE) and metabolic flexibility in physically active women. METHODS: Participants (N.=20) completed a 3-day food log and a standardized bout of high-intensity interval training to determine EE and respiratory exchange ratio (RER). EE and RER were measured via indirect calorimetry at rest (PRE) and immediately (IP), 30 minutes (30 min), and 60 minutes postexercise (60 min). To evaluate metabolic flexibility, RER changes were calculated from PRE to IP, IP to 30 min, and IP to 60 min. For each macronutrient, participants were categorized into high- and low-intake groups using a median split. RESULTS: No significant correlations were observed between macronutrient distribution and EE when covaried for lean mass (all P≥0.232), and ANCOVAs revealed no significant group × time interactions (all P≥0.241). Fat intake was not associated with ∆RER (all P≥0.477). Correlations between PRO intake and ∆RER approached significance (r=0.373-0.411; P=0.079-0.115), as did inverse associations between CHO and ∆RER (r=-0.404 - -0.409; P=0.084-0.087). Lower RER values were observed in the low-CHO group at 30 min and 60 min (P=0.030) compared to high-CHO. Higher RER values were observed in the high-PRO group at IP (P=0.042) compared to low-PRO. Estradiol was not correlated with RER at any time point, or different between diet groups (all P≥0.401). CONCLUSIONS: Results suggest that high PRO and low CHO intakes are associated with greater metabolic flexibility in women.

Cordyceps militaris Improves Tolerance to High-Intensity Exercise After Acute and Chronic Supplementation.

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 interaction for VO2max (p = 0.364), VT (p = 0.514), TTE (p = 0.540), RPP (p = 0.134), AvgP (p = 0.398), or %drop (p = 0.823). After 3 weeks, VO2max significantly improved (p = 0.042) in MR (+4.8 ml·kg-1·min-1), but not PL (+0.9 ml·kg-1·min-1). Analysis of 95% confidence intervals revealed significant improvements in TTE after 1- (+28.1 s) and 3 weeks (+69.8 s) in MR, but not PL, with additional improvements in VO2max (+4.8 ml·kg-1·min-1) and VT (+0.7 l·min-1) after 3 weeks. 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.

Seasonal Effects on Body Composition, Muscle Characteristics, and Performance of Collegiate Swimmers and Divers.

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 the university athletic Web site. RESULTS: Lean mass (P = .016), arm lean mass (P = .008), and muscle cross-sectional area (P = .03) were higher at postseason, whereas body fat percentage (P = .041) and echo intensity (P = .0007) were lower at postseason. Performance improved from preseason to postseason in all event groups (sprinters, distance swimmers, and divers; P < .05). CONCLUSIONS: Body composition and muscle characteristics improved through 1 training season, which may have implications for performance. Quantifying body composition and muscle characteristics may be beneficial for professionals who work with athletes in order to improve performance and prevent injury.

Effects of pomegranate extract on blood flow and vessel diameter after high-intensity exercise in young, healthy adults.

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). Vessel diameter increased significantly 30minPost RSA according to CI and resulted in a significant interaction IPost and 30minPost RTF (P < .05). With PE, according to CI, average and peak power output increased significantly in sprint 5 of the RSA (P < .05). There was no significant difference between PE and PL for bench (P = .25) or leg press (P = .15) repetitions. Acute PE supplementation enhanced vessel diameter and blood flow, suggesting possible exercise performance enhancement from increased delivery of substrates and oxygen. The acute timing and capsule form of PE may be advantageous to athletic populations due to ergogenic effects, taste, and convenience.

Body Composition and Muscle Characteristics of Division I Track and Field Athletes.

The purpose of this study was to evaluate event-specific body composition and muscle characteristics of track and field athletes and to assess body composition changes after 1 year. Sixty collegiate track and field athletes (mean ± SD; age = 19.2 ± 1.4 years, height = 174.6 ± 9.0 cm, and weight = 71.5 ± 12.5 kg) were stratified into 6 event groups. Total and regional body composition measurements were assessed using dual-energy x-ray absorptiometry. A panoramic scan of the vastus lateralis was taken with B-mode ultrasound to determine muscle cross-sectional area and echo intensity (EI). Body composition measurements were repeated a year later in a subset of returning athletes (n = 33). Throwers had significantly more absolute fat mass (FM; 21.6 ± 11.0 kg), total body mass (89.7 ± 17.4 kg), percent fat (23.6 ± 7.8), and trunk fat (9.4 ± 5.8 kg) than all other event groups (p ≤ 0.05). Throwers had the most absolute lean mass (LM; 64.2 ± 11.7 kg; p > 0.05), but relative to body mass had relatively less LM (0.72 ± 0.08 kg; p ≤ 0.05). Despite high FM, throwers had lower EI (63.4 ± 5.2 a.u). After 1 year, relative armLM increased slightly in all event groups (p ≤ 0.05). Evaluation of muscle characteristics in addition to total and regional body composition may be valuable for improving performance, injury prevention, and assessing health risks. With appropriate training, track and field athletes may be able to minimize losses in LM and gains in FM between seasons.

Effects of coffee and caffeine anhydrous on strength and sprint performance.

Caffeine and coffee are widely used among active individuals to enhance performance. The purpose of the current study was to compare the effects of acute coffee (COF) and caffeine anhydrous (CAF) intake on strength and sprint performance. Fifty-four resistance-trained males completed strength testing, consisting of one-rep max (1RM) and repetitions to fatigue (RTF) at 80% of 1RM for leg press (LP) and bench press (BP). Participants then completed five, 10-second cycle ergometer sprints separated by one minute of rest. Peak power (PP) and total work (TW) were recorded for each sprint. At least 48 hours later, participants returned and ingested a beverage containing CAF (300 mg flat dose; yielding 3-5 mg/kg bodyweight), COF (8.9 g; 303 mg caffeine), or placebo (PLA; 3.8 g non-caloric flavouring) 30 minutes before testing. LP 1RM was improved more by COF than CAF (p = .04), but not PLA (p = .99). Significant interactions were not observed for BP 1RM, BP RTF, or LP RTF (p > .05). There were no sprint × treatment interactions for PP or TW (p > .05). 95% confidence intervals revealed a significant improvement in sprint 1 TW for CAF, but not COF or PLA. For PLA, significant reductions were observed in sprint 4 PP, sprint 2 TW, sprint 4 TW, and average TW; significant reductions were not observed with CAF or COF. Neither COF nor CAF improved strength outcomes more than PLA, while both groups attenuated sprint power reductions to a similar degree. Coffee and caffeine anhydrous may be considered suitable pre-exercise caffeine sources for high-intensity exercise.

Effects of Coffee and Caffeine Anhydrous Intake During Creatine Loading.

The purpose of this study was to determine the effect of 5 days of creatine (CRE) loading alone or in combination with caffeine anhydrous (CAF) or coffee (COF) on upper-body and lower-body strength and sprint performance. Physically active males (n = 54; mean ± SD; age = 20.1 ± 2.1 years; weight = 78.8 ± 8.8 kg) completed baseline testing, consisting of 1 repetition maximum (1RM) and repetitions to fatigue with 80% 1RM for bench press and leg press, followed by a repeated sprint test of five, 10-second sprints separated by 60-second rest on a cycle ergometer to determine peak power (PP) and total power (TP). At least 72 hours later, subjects were randomly assigned to supplement with CRE (5 g of CRE monohydrate, 4 times per day; n = 14), CRE + CAF (CRE +300 mg·d of CAF; n = 13), CRE + COF (CRE +8.9 g of COF, yielding 303 mg of CAF; n = 13), or placebo (PLA; n = 14) for 5 days. Serum creatinine (CRN) was measured before and after supplementation, and on day 6, participants repeated pretesting procedures. Strength measures were improved in all groups (p ≤ 0.05), with no significant time × treatment interactions. No significant interaction or main effects were observed for PP. For TP, a time × sprint interaction was observed (p ≤ 0.05), with no significant interactions among treatment groups. A time × treatment interaction was observed for serum CRN values (p ≤ 0.05) that showed increases in all groups except PLA. Four subjects reported mild gastrointestinal discomfort with CRE + CAF, with no side effects reported in other groups. These findings suggest that neither CRE alone nor in combination with CAF or COF significantly affected performance compared with PLA.

The acute effect of exercise modality and nutrition manipulations on post-exercise resting energy expenditure and respiratory exchange ratio in women: a randomized trial.

BACKGROUND: The purpose of this study was to examine the effect of exercise modality and pre-exercise carbohydrate (CHO) or protein (PRO) ingestion on post-exercise resting energy expenditure (REE) and respiratory exchange ratio (RER) in women. METHODS: Twenty recreationally active women (mean ± SD; age 24.6 ± 3.9 years; height 164.4 ± 6.6 cm; weight 62.7 ± 6.6 kg) participated in this randomized, crossover, double-blind study. Each participant completed six exercise sessions, consisting of three exercise modalities: aerobic endurance exercise (AEE), high-intensity interval running (HIIT), and high-intensity resistance training (HIRT); and two acute nutritional interventions: CHO and PRO. Salivary samples were collected before each exercise session to determine estradiol-ß-17 and before and after to quantify cortisol. Post-exercise REE and RER were analyzed via indirect calorimetry at the following: baseline, immediately post (IP), 30 minutes (30 min) post, and 60 minutes (60 min) post exercise. A mixed effects linear regression model, controlling for estradiol, was used to compare mean longitudinal changes in REE and RER. RESULTS: On average, HIIT produced a greater REE than AEE and HIRT (p < 0.001) post exercise. Effects of AEE and HIRT were not significantly different for post-exercise REE (p = 0.1331). On average, HIIT produced lower RER compared to either AEE or HIRT after 30 min (p < 0.001 and p = 0.0169, respectively) and compared to AEE after 60 min (p = 0.0020). On average, pre-exercise PRO ingestion increased post-exercise REE (p = 0.0076) and decreased post-exercise RER (p < 0.0001) compared to pre-exercise CHO ingestion. CONCLUSION: HIIT resulted in the largest increase in REE and largest reduction in RER.

Muscle size, quality, and body composition: characteristics of division I cross-country runners.

The primary purpose of this study was to identify the relationship between muscle cross-sectional area (mCSA), echo intensity (EI), and body composition of Division I cross-country runners. The secondary purpose was to examine differences in these variables in athletes stratified based on stress-fracture (SFx) history. Thirty-six athletes were stratified based on sex and SFx history. A panoramic scan vastus lateralis was performed using a GE Logiq-e B-mode ultrasound. Echo intensity and mCSA were determined from the scan using a grayscale imaging software (ImageJ). Body composition measures were determined using dual-energy x-ray absorptiometry. For females, mCSA was significantly correlated with left leg lean mass (LM; R = 0.54) and EI (R = -0.57). Lean mass was significantly correlated with bone mineral density (BMD; R = 0.58) and bone mineral content (BMC; R = 0.56), whereas BMC was also correlated with leg LM (R = 0.72). For males, mCSA was significantly correlated with leg LM (R = 0.66), BMD (R = 0.50), and BMC (R = 0.54). Leg LM was significantly correlated with BMD (R = 0.53) and BMC (R = 0.77). Personal best times for males were significantly correlated with fat mass (R = 0.489) and %fat (R = 0.556) for the 10- and 5-km races, respectively. Female and male athletes with a history of SFx were not significantly different across any variables when compared with athletes with no history. These correlations suggest that more muscle mass may associate with higher BMD and BMC for stronger bone structure. Modifications in training strategies to include heavy resistance training and plyometrics may be advantageous for preventing risk factors associated with SFx reoccurrence.