bluuebunny/crossref_metadata_2025 huggingface dataset:
Oral Creatine Supplementation’s Decrease of Blood Lactate During Exhaustive, Incremental Cycling
Authors: Oliver Jonathan M. , Joubert Dustin P. , Martin Steven E. , Crouse Stephen F.
Published: August 2016

Purpose:

To determine the effects of creatine supplementation on blood lactate during incremental cycling exercise.

Methods:

Thirteen male subjects (M ± SD 23 ± 2 yr, 178.0 ± 8.1 cm, 86.3 ± 16.0 kg, 24% ± 9% body fat) performed a maximal, incremental cycling test to exhaustion before (Pre) and after (Post) 6 d of creatine supplementation (4 doses/d of 5 g creatine + 15 g glucose). Blood lactate was measured at the end of each exercise stage during the protocol, and the lactate threshold was determined as the stage before achieving 4 mmol/L. Lactate concentrations during the incremental test were analyzed using a 2 (condition) × 6 (exercise stage) repeated-measures ANOVA. Differences in power at lactate threshold, power at exhaustion, and total exercise time were determined by paired t tests and are presented as M ± SD.

Results:

Lactate concentrations were reduced during exercise after supplementation, demonstrating a significant condition effect (p = .041). There was a tendency for increased power at the lactate threshold (Pre 128 ± 45 W, Post 143 ± 26 W; p = .11). Total time to fatigue approached significant increases (Pre 22.6 ± 3.2 min, Post 23.3 ± 3.3 min; p = .056), as did maximal power output (Pre 212.5 ± 32.5 W, Post 220 ± 34.6 W; p = .082).

Conclusions:

Our findings demonstrate that creatine supplementation decreases lactate during incremental cycling exercise and tends to raise lactate threshold. Therefore, creatine supplementation could potentially benefit endurance athletes.
Growth-Hormone Responses to Consecutive Exercise Bouts With Ingestion of Carbohydrate Plus Protein
Authors: Betts James A. , Stokes Keith A. , Toone Rebecca J. , Williams Clyde
Published: August 2016

Endocrine responses to repeated exercise have barely been investigated, and no data are available regarding the mediating influence of nutrition. On 3 occasions, participants ran for 90 min at 70% VO2max (R1) before a second exhaustive treadmill run at the same intensity (R2; 91.6 ± 17.9 min). During the intervening 4-hr recovery, participants ingested either 0.8 g sucrose · kg−1 · hr−1 with 0.3 g · kg−1 · hr−1 whey-protein isolate (CHO-PRO), 0.8 g sucrose · kg−1 · hr−1 (CHO), or 1.1 g sucrose · kg−1 · hr−1 (CHO-CHO). The latter 2 solutions therefore matched the former for carbohydrate or for available energy, respectively. Serum growth-hormone concentrations increased from 2 ± 1 μg/L to 17 ± 8 μg/L during R1 considered across all treatments (M ± SD; p ≤ .01). Concentrations were similar immediately after R2 irrespective of whether CHO or CHO-CHO was ingested (19 ± 4 μg/L and 19 ± 5 μg/L, respectively), whereas ingestion of CHO-PRO produced an augmented response (31 ± 4 μg/L; p ≤ .05). Growth-hormone-binding protein concentrations were unaffected by R1 but increased similarly across all treatments during R2 (from 414 ± 202 pmol/L to 577 ± 167 pmol/L; p ≤ .01), as was the case for plasma total testosterone (from 9.3 ± 3.3 nmol/L to 14.7 ± 4.6 nmol/L; p ≤ .01). There was an overall treatment effect for serum cortisol (p ≤ .05), with no specific differences at any given time point but lower concentrations immediately after R2 with CHO-PRO (608 ± 133 nmol/L) than with CHO (796 ± 278 nmol/L) or CHO-CHO (838 ± 134 nmol/L). Ingesting carbohydrate with added whey-protein isolate during short-term recovery from 90 min of treadmill running increases the growth-hormone response to a second exhaustive exercise bout of similar duration.
A Simple Method for Increasing Levels of High-Density Lipoprotein Cholesterol: A Pilot Study of Combination Aerobic- and Resistance-Exercise Training
Authors: Tseng Ming-Lang , Ho Chien-Chang , Chen Shih-Chang , Huang Yi-Chia , Lai Cheng-Hsiu , Liaw Yung-Po
Published: August 2016

Evidence suggests that physical activity has a beneficial effect of elevated high-density lipoprotein cholesterol (HDL-C) on reducing coronary artery risk. However, previous studies show contrasting results for this association between different types of exercise training (i.e., aerobic, resistance, or combined aerobic and resistance training). The aim of this study was to determine which type of exercise training is more effective in increasing HDL-C levels. Forty obese men, age 18–29 yr, were randomized into 4 groups: an aerobic-training group (n = 10), a resistance-training group (n = 10), a combined-exercise-training group (n = 10), and a control group (n = 10). After a 12-wk exercise program, anthropometrics, blood biochemical variables, and physical-fitness components were compared with the data obtained at the baseline. Multiple-regression analysis was used to evaluate the association between different types of exercise training and changes in HDL-C while adjusting for potential confounders. The results showed that with the control group as the comparator, the effects of combined-exercise training (β = 4.17, p < .0001), aerobic training (β = 3.65, p < .0001), and resistance training (β = 2.10, p = .0001) were positively associated with increase in HDL-C after adjusting for potential confounders. Our findings suggested that a short-term exercise program can play an important role in increasing HDL-C levels; either aerobic or resistance training alone significantly increases the HDL-C levels, but the improvements are greatest with combined aerobic and resistance training.
Influence of Female Sports Dietitians’ Physical Characteristics on Athlete Perception of Effectiveness
Authors: Lovell Geoff P. , Parker John K. , Slater Gary J.
Published: August 2016

Research in sports-science disciplines such as sport psychology has demonstrated that practitioners’ physical characteristics influence clients’ perceptions of their effectiveness, potentially mediating the efficacy of subsequent interventions. However, very little research has been directed toward this issue for sports dietitians (SDs), the health professionals whom athletes are likely to engage to assist with manipulation of traits of physique. Therefore, the purpose of this investigation was to determine whether SDs’ phenotype, specifically body-mass index (BMI), and type of dress influence potential clients’ preference to consult them for dietetic support and if this affects their perceived effectiveness.

Methods:

One hundred volunteers (mean age 18.7 ± 0 .8 years) all participating in regular competitive sport, classified by gender (male, n = 55, or female, n = 45) and competitive standard (elite/subelite, n = 68, or club/recreational, n = 32) viewed slides representing four concurrently presented computer-generated images of the same female SD manipulated to represent different BMIs and dress types. Participants were asked to rank the SDs in order of their preference to work with them and, second, to rate their perceived effectiveness of each of the SDs.

Results:

Key findings included the observation of a significant BMI main effect F(6, 91) = 387.39, p < .001 (effect size .96), with participants’ ranking of preference and rating of perceived effectiveness of female SDs decreasing with increasing BMI.

Conclusion:

SDs should consider their physical appearance when meeting with athletes, as this may affect their perceived efficacy.
The Acute Effects of L-arginine on Hormonal and Metabolic Responses During Submaximal Exercise in Trained Cyclists
Authors: Forbes Scott C. , Harber Vicki , Bell Gordon J.
Published: August 2016

L-arginine may enhance endurance performance mediated by two primary mechanisms including enhanced secretion of endogenous growth hormone (GH) and as a precursor of nitric oxide (NO); however, research in trained participants has been equivocal. The purpose was to investigate the effect of acute L-arginine ingestion on the hormonal and metabolic response during submaximal exercise in trained cyclists. Fifteen aerobically trained men (age: 28 ± 5 y; body mass: 77.4 ± 9.5 kg; height: 180.9 ± 7.9 cm; VO2max: 59.6 ± 5.9 ml·kg-1·min−1) participated in a randomized, double-blind, crossover study. Subjects consumed L-arginine (ARG; 0.075 g·kg-1 body mass) or a placebo (PLA) before performing an acute bout of submaximal exercise (60 min at 80% of power output achieved at ventilatory threshold). The ARG condition significantly increased plasma L-arginine concentrations (~146%), while no change was detected in the PLA condition. There were no differences between conditions for GH, nonesterified fatty acids (NEFA), lactate, glucose, VO2, VCO2, RER, CHO oxidation, and NOx. There was reduced fat oxidation at the start of exercise (ARG: 0.36 ± 0.25 vs. PLA: 0.42 ± 0.23 g·min−1, p < .05) and an elevated plasma glycerol concentrations at the 45-min time point (ARG: 340.3 vs. PLA: 288.5 μmol·L-1, p < .05) after L-arginine consumption. In conclusion, the acute ingestion of L-arginine did not alter any hormonal, metabolic, or cardio-respiratory responses during submaximal exercise except for a small but significant increase in glycerol at the 45-min time point and a reduction in fat oxidation at the start of exercise.
Influence of Growth Rate on Nitrogen Balance in Adolescent Sprint Athletes
Authors: Aerenhouts Dirk , Van Cauwenberg Jelle , Poortmans Jacques Remi , Hauspie Ronald , Clarys Peter
Published: August 2016

This study aimed to estimate nitrogen balance and protein requirements in adolescent sprint athletes as a function of growth rate and physical development. Sixty adolescent sprint athletes were followed up biannually over a 2-yr period. Individual growth curves and age at peak height velocity were determined. Skeletal muscle mass (SMM) was estimated based on anthropometric measurements and fat mass was estimated by underwater densitometry. Seven-day diet and physical activity diaries were completed to estimate energy balance and protein intake. Nitrogen analysis of 24-hr urine samples collected on 1 weekday and 1 weekend day allowed calculation of nitrogen balance. Body height, weight, and SMM increased throughout the study period in both genders. Mean protein intakes were between 1.4 and 1.6 g kg−1 day−1 in both genders. A protein intake of 1.46 g kg−1 day−1 in girls and 1.35 g kg−1 day−1 in boys was needed to yield a positive nitrogen balance. This did not differ between participants during and after their growth spurt. None of the growth parameters was significantly related to nitrogen balance. It can be concluded that a mean protein intake around 1.5 g kg−1 day−1 was sufficient to stay in a positive nitrogen balance, even during periods of peak growth. Therefore, protein intake should not be enhanced in peak periods of linear or muscular growth.
The Effects of Season-Long Vitamin D Supplementation on Collegiate Swimmers and Divers
Authors: Lewis Regina M. , Redzic Maja , Thomas D. Travis
Published: August 2016

The purpose of this 6-month randomized, placebo-controlled trial was to determine the effect of season-long (September–March) vitamin D supplementation on changes in vitamin D status, which is measured as 25(OH) D, body composition, inflammation, and frequency of illness and injury. Forty-five male and female athletes were randomized to 4,000 IU vitamin D (n = 23) or placebo (n = 22). Bone turnover markers (NTx and BSAP), 25(OH)D, and inflammatory cytokines (TNF-alpha, IL-6, and IL1-β) were measured at baseline, midpoint, and endpoint. Body composition was assessed by DXA and injury and illness data were collected. All athletes had sufficient 25(OH)D (> 32 ng/ml) at baseline (mean: 57 ng/ml). At midpoint and endpoint, 13% and 16% of the total sample had 25(OH)D < 32 ng/ml, respectively. 25(OH)D was not positively correlated with bone mineral density (BMD) in the total body, proximal dual femur, or lumbar spine. In men, total body (p = .04) and trunk (p = .04) mineral-free lean mass (MFL) were positively correlated with 25(OH)D. In women, right femoral neck BMD (p = .02) was positively correlated with 25(OH)D. 25(OH)D did not correlate with changes in bone turnover markers or inflammatory cytokines. Illness (n = 1) and injury (n = 13) were not related to 25(OH)D; however, 77% of injuries coincided with decreases in 25(OH)D. Our data suggests that 4,000 IU vitamin D supplementation is an inexpensive intervention that effectively increased 25(OH)D, which was positively correlated to bone measures in the proximal dual femur and MFL. Future studies with larger sample sizes and improved supplement compliance are needed to expand our understanding of the effects of vitamin D supplementation in athletes.
The Effects of High-Intensity Intermittent Exercise Compared With Continuous Exercise on Voluntary Water Ingestion
Authors: Mears Stephen A. , Shirreffs Susan M.
Published: August 2016

Water intake occurs following a period of high-intensity intermittent exercise (HIIE) due to sensations of thirst yet this does not always appear to be caused by body water losses. Thus, the aim was to assess voluntary water intake following HIIE. Ten healthy males (22 ± 2 y, 75.6 ± 6.9 kg, VO2peak 57.3 ± 11.4 m·kg−1·min−1; mean± SD) completed two trials (7–14 d apart). Subjects sat for 30 min then completed an exercise period involving 2 min of rest followed by 1 min at 100% VO2peak repeated for 60 min (HIIE) or 60 min continuously at 33% VO2peak (LO). Subjects then sat for 60 min and were allowed ad libitum water intake. Body mass was measured at start and end of trials. Serum osmolality, blood lactate, and sodium concentrations, sensations of thirst and mouth dryness were measured at baseline, postexercise and after 5, 15, 30, and 60 min of recovery. Vasopressin concentration was measured at baseline, postexercise, 5 min, and 30 min. Body mass loss over the whole trial was similar (HIIE: 0.77 ± 0.50; LO: 0.85 ± 0.55%; p = .124). Sweat lost during exercise (0.78 ± 0.22 vs. 0.66 ± 0.26 L) and voluntary water intake during recovery (0.416 ± 0.299 vs. 0.294 ± 0.295 L; p < .05) were greater in HIIE. Serum osmolality (297 ± 3 vs. 288 ± 4mOsmol·kg−1), blood lactate (8.5 ± 2.7 vs. 0.7 ± 0.4 mmol·L−1), serum sodium (146 ± 1 vs. 143 ± 1 mmol·L−1) and vasopressin (9.91 ± 3.36 vs. 4.43 ± 0.86 pg·ml−1) concentrations were higher after HIIE (p < .05) and thirst (84 ± 7 vs. 60 ± 21) and mouth dryness (87 ± 7 vs. 64 ± 23) also tended to be higher (p = .060). Greater voluntary water intake after HIIE was mainly caused by increased sweat loss and the consequences of increased serum osmolality mainly resulting from higher blood lactate concentrations.
The Effects of a Single Dose of Concentrated Beetroot Juice on Performance in Trained Flatwater Kayakers
Authors: Muggeridge David J. , Howe Christopher C. F. , Spendiff Owen , Pedlar Charles , James Philip E. , Easton Chris
Published: August 2016

The aim of the current study was to determine the effects of dietary nitrate ingestion on parameters of submaximal and supramaximal exercise and time trial (TT) performance in trained kayakers. Eight male kayakers completed four exercise trials consisting of an initial discontinuous graded exercise test to exhaustion and three performance trials using a kayak ergometer. The performance trials were composed of 15 min of paddling at 60% of maximum work rate, five 10-s all-out sprints, and a 1 km TT. The second and third trials were preceded by ingestion of either 70 ml nitrate-rich concentrated beetroot juice (BR) or tomato juice (placebo [PLA]) 3 hr before exercise using a randomized crossover design. Plasma nitrate (PLA: 33.8 ± 1.9 μM, BR: 152 ± 3.5 μM) and nitrite (PLA: 519.8 ± 25.8, BR: 687.9 ± 20 nM) were higher following ingestion of BR compared with PLA (both p < .001). VO2 during steady-state exercise was lower in the BR trial than in the PLA trial (p = .010). There was no difference in either peak power in the sprints (p = .590) or TT performance between conditions (PLA: 277 ± 5 s, BR: 276 ± 5 s, p = .539). Despite a reduction in VO2, BR ingestion appears to have no effect on repeated supramaximal sprint or 1 km TT kayaking performance. A smaller elevation in plasma nitrite following a single dose of nitrate and the individual variability in this response may partly account for these findings.
Case Study: Nutrition and Hydration Status during 4,254 km of Running Over 78 Consecutive Days
Authors: Dempster Sarah , Britton Rhiannon , Murray Andrew , Costa Ricardo J. S.
Published: August 2016

The aims of this study were to assess the dietary intake and monitor self-reported recovery quality and clinical symptomology of a male ultra-endurance runner who completed a multiday ultra-endurance running challenge covering 4,254 km from North Scotland to the Moroccan Sahara desert over 78 consecutive days. Food and fluid intakes were recorded and analyzed through dietary analysis software. Body mass (BM) was determined before and after running each day, and before sleep. Clinical symptomology and perceived recovery quality were recorded each day. Whole blood hemoglobin and serum ferritin were determined before and after the challenge. Total daily energy (mean ± SD: 23.2 ± 3.2MJ·day−1) and macronutrient intake (182 ± 31g·day−1 protein, 842 ± 115g·day−1 carbohydrate, 159 ± 55 g·day−1 fat) met consensus nutritional guidelines for endurance performance. Total daily water intake through foods and fluids was 4.8 ± 2.0L·day−1. Water and carbohydrate intake rates during running were 239 ± 143ml·h−1 and 56 ± 19g·h−1, respectively. Immediately after running, carbohydrate and protein intakes were 1.3 ± 1.0g·kg BM−1 and 0.4 ± 0.2g·kg BM−1, respectively. Daily micronutrient intakes ranged from 109 to 662% of UK RNIs. Prerunning BM was generally maintained throughout. Overall exercise-induced BM loss averaged 0.8 ± 1.0%; although BM losses of ≥ 2% occurred in the latter stages, a reflection of the warmer climate. Varying degrees of self-reported perceived recovery quality and clinical symptomology occurred throughout the challenge. This case study highlights oscillations in dietary habits along 78 consecutive days of ultra-endurance running, dependent on changes in ambient conditions and course topography. Nevertheless, nutrition and hydration status were maintained throughout the challenge. Despite dietary iron intake above RNI and iron supplementation, this alone did not prevent deficiency symptoms.
Is There a Specific Role for Sucrose in Sports and Exercise Performance?
Authors: Wallis Gareth A. , Wittekind Anna
Published: August 2016

The consumption of carbohydrate before, during, and after exercise is a central feature of the athlete’s diet, particularly those competing in endurance sports. Sucrose is a carbohydrate present within the diets of athletes. Whether sucrose, by virtue of its component monosaccharides glucose and fructose, exerts a meaningful advantage for athletes over other carbohydrate types or blends is unclear. This narrative reviews the literature on the influence of sucrose, relative to other carbohydrate types, on exercise performance or the metabolic factors that may underpin exercise performance. Inference from the research to date suggests that sucrose appears to be as effective as other highly metabolizable carbohydrates (e.g., glucose, glucose polymers) in providing an exogenous fuel source during endurance exercise, stimulating the synthesis of liver and muscle glycogen during exercise recovery and improving endurance exercise performance. Nonetheless, gaps exist in our understanding of the metabolic and performance consequences of sucrose ingestion before, during, and after exercise relative to other carbohydrate types or blends, particularly when more aggressive carbohydrate intake strategies are adopted. While further research is recommended and discussed in this review, based on the currently available scientific literature it would seem that sucrose should continue to be regarded as one of a variety of options available to help athletes achieve their specific carbohydrate-intake goals.
Beer as a Sports Drink? Manipulating Beer’s Ingredients to Replace Lost Fluid
Authors: Desbrow Ben , Murray Daniel , Leveritt Michael
Published: August 2016

Purpose:

To investigate the effect of manipulating the alcohol and sodium content of beer on fluid restoration following exercise.

Method:

Seven male volunteers exercised on a cycle ergometer until 1.96 ± 0.25% body mass (mean± SD) was lost. Participants were then randomly allocated a different beer to consume on four separate occasions. Drinks included a low-alcohol beer (2.3% ABV; LightBeer), a low-alcohol beer with 25 mmol×L−1 of added sodium (LightBeer+25), a full-strength beer (4.8% ABV; Beer), or a full-strength beer with 25 mmol×L−1 of added sodium (Beer+25). Volumes consumed were equivalent to 150% of body mass loss during exercise and were consumed over a 1h period. Body mass and urine samples were obtained before and hourly for 4 hr after beverage consumption.

Results:

Significantly enhanced net fluid balance was achieved following the LightBeer+25 trial (–1.02 ± 0.35 kg) compared with the Beer (–1.59 ± 0.32 kg) and Beer+25 (–1.64 ± 0.28 kg) treatments. Accumulated urine output was significantly lower in the LightBeer+25 trial (1477 ± 485 ml) compared with the Beer+25 (2101 ± 482 ml) and Beer (2175 ± 372 ml) trials.

Conclusion:

A low alcohol beer with added sodium offers a potential compromise between a beverage with high social acceptance and one which avoids the exacerbated fluid losses observed when consuming full strength beer.
Monitoring Changes in Lean Mass of Elite Male and Female Swimmers
Authors: Pyne David B. , Anderson Megan E. , Hopkins Will G.
Published: August 2016

Purpose:

To characterize within-subject changes in anthropometric characteristics of elite swimmers within and between seasons.

Methods:

The subjects were 77 elite swimmers (31 females, 46 males, age 15 to 30 years) monitored over 0.4 to 9.2 years. One anthropometrist recorded their body mass (M) and sum of 7 skin-fold thicknesses (S) on 2042 occasions over 14 years from phase to phase within a season and over consecutive seasons. We estimated change in lean mass using a newly derived index (LMI) that tracked changes in M controlled for changes in S.

Results:

The LMI is M/Sx, where x = 0.16 ± 0.04 for females and 0.15 ± 0.05 for males (mean ± SD). The LMI of males increased 1.1% (95% confidence limits ± 0.2%) between preseason and taper phases, almost twice as much as that of females (0.6% ± 0.3%). During the same period, M and S fell by ~1% and ~11%, respectively. From season to season LMI increased by 0.9% (0.8% to 1.0%) for males and 0.5% (0.3% to 0.7%) for females. All these within-subject effects on LMI were well defined (±~0.3%). The typical variation (SD) of an individual’s LMI was 1.2% for assessments within a season and 1.9% between seasons, with a short-term technical error of measurement of ~0.5%.

Conclusion:

Coaches and conditioners should typically expect a twofold greater increase in lean mass in male swimmers within and between seasons than in females. An LMI of the form M/Sx should be useful for monitoring individual swimmers and athletes in other sports in which body composition affects performance.
The Effect of Training Volume on the Acute Response and Adaptations to Resistance Training
Authors: Brandenburg Jason , Docherty David
Published: August 2016

Purpose:

To examine the acute response to 2 resistance-exercise protocols performed to repetition failure, but different in load configuration, and determine whether the acute response was related to strength increases after 8 weeks of training.

Methods:

Eighteen resistance-trained men completed a single session of 2 resistance-exercise protocols. The constant-load protocol (CL) required subjects to complete 3 sets of single-arm preacher curls (elbow flexion) to failure using a load of ~77% 1RM. The reduced-load protocol (RL) was similar, but training load was reduced for the second and third sets. Maximal isometric force (MVIC) and blood lactate were assessed preprotocol and postprotocol to determine the acute response. For the 8-week training phase, subjects (N = 12) were divided into 2 programs, each corresponsing to 1 of the protocols. Strength was measured before and after training.

Results:

MVIC decreased from 106.2 ± 13.8 to 84.3 ± 12.1 N · m and from 109.1 ± 14.7 to 82.5 ± 13 N · m after the CL and RL protocols, respectively. The decrements in MVIC were significant (P < .001), with the decline after RL tending to be greater (P = .051). Postprotocol blood lactate concentrations after CL and RL were 3.4 ± 1.1 and 4.1 ± 1.3 mmol/L, respectively, with greater increases after RL (P = .036). Similar and significant 1RM strength increases were observed after both programs (from 20.7 ± 2.7 to 23.3 ± 3.5 kg after CL and from 22.4 ± 2.9 to 25.5 ± 3.2 kg after RL; P < .001).

Conclusion:

The similar increases in strength suggest that either the greater acute response to RL was not related to the increases in strength or a minimal (threshold) response was achieved during both programs.
The Work Rate Corresponding to Ventilatory Threshold During Steady-State and Ramp Exercise
Authors: Faude Oliver , Meyer Tim , Kindermann Wilfried
Published: August 2016

Purpose:

The work rate (WR) corresponding to ventilatory threshold (VT) is an appropriate intensity for regenerative and low-intensity training sessions. During incremental ramp exercise, VO2 increase lags behind WR increase. Traditionally, a VO2 time delay (td) of 45 seconds is used to calculate the WR at VT from such tests. Considerable inaccuracies were observed when using this constant td. Therefore, this study aimed at reinvestigating the temporal relationship between VO2 and WR at VT.

Methods:

20 subjects (VO2peak 49.9 to 72.6 mL · min–1 · kg–1) performed a ramp test in order to determine VT and a subsequent steady-state test during which WR was adjusted to elicit the VO2 corresponding to VT. The difference in WR and heart rate at VT was calculated between the ramp and the steady-state test (WRdiff, HRdiff) as well as the time delay corresponding to WRdiff during ramp exercise.

Results:

Mean values were td = 85 ± 26 seconds (range 38 to 144), WRdiff = 45 ± 12 W (range 23 to 67), HRdiff = 1 ± 9 beats/min (range –21 to +15). The limits of agreement for the difference between WR at VT during ramp and steady-state exercise were ± 24 W. No signifi cant influence on td, WRdiff, or HRdiff from differences in endurance capacity (VO2peak and VT; P > .10 for all correlations) or ramp increment (P = .26, .49, and .85, respectively) were observed.

Conclusion:

The wide ranges of td, WRdiff, and HRdiff prevent the derivation of exact training guidelines from single-ramp tests. It is advisable to perform a steady-state test to exactly determine the WR corresponding to VT.
Training for Performance: Insights From Molecular Biology
Authors: Coffey Vernon G. , Hawley John A.
Published: August 2016

In this commentary the authors discuss the molecular basis of the training adaptation and review the role of several key signaling proteins important in the adaptation to endurance and resistance training.
Spirometry Measurements During an Episode of Exercise-Related Transient Abdominal Pain
Authors: Morton Darren P. , Callister Robin
Published: August 2016

Purpose:

To determine whether changes in lung function are associated with exercise-related transient abdominal pain (ETAP).

Methods:

Twenty-eight subjects susceptible to ETAP performed a flow-volume loop before (pre) and after (post) treadmill exercise. Fourteen of the subjects developed symptoms of ETAP during the exercise and completed the flow-volume loop while the pain was present. The remaining 14 subjects reported no symptoms of ETAP.

Results:

Forced inspiratory vital capacity was essentially unchanged from pre to post in both groups (ETAP group −0.8% ± 5.1%, comparison group −0.9% ± 6.5%). Peak inspiratory-flow rate increased in both the ETAP group (12.4% ± 16.2%) and the comparison group (17.9% ± 16.6%), but the difference between groups (−4.6%, standardized effect size [EF] = −0.17) was trivial. Forced expiratory vital capacity decreased by approximately 4% in both groups (ETAP group −3.9% ± 3.3%, comparison group −4.0% ± 5.1%). Small differences in the mean change from pre to post between groups were recorded for peak expiratory-flow rate (−7.4%, EF = −0.28) and the forced expiratory volume in the first second of the test (−4.4%, EF = −0.44).

Conclusions:

ETAP does not appear to be associated with reduced inspiratory performance, suggesting that the diaphragm is not implicated directly in the etiology of ETAP. Expiratory power might be slightly reduced during an episode of ETAP, but the magnitude of this effect is unlikely to compromise exercise performance.
A Comparison of Time–Motion Analysis Methods for Field-Based Sports
Authors: Roberts Simon , Trewartha Grant , Stokes Keith
Published: August 2016

Purpose:

To assess the validity of a digitizing time–motion-analysis method for field-based sports and compare this with a notational-analysis method using rugby-union match play.

Method:

Five calibrated video cameras were located around a rugby pitch, and 1 subject completed prescribed movements within each camera’s view. Running speeds were measured using photocell timing gates. Two experienced operators digitized video data (operator 1 on 2 occasions) to allow 2-dimensional reconstruction of the prescribed movements.

Results:

Accuracy for total distance calculated was within 2.1% of the measured distance. For intraoperator and interoperator reliability, calculated distances were within 0.5% and 0.9%, respectively. Calculated speed was within 8.0% of measured photocell speed with intraoperator and interoperator reliability of 3.4% and 6.0%, respectively. For the method comparison, two 20-minute periods of rugby match play were analyzed for 5 players using the digitizing method and a notational time–motion method. For the 20-minute periods, overall mean absolute differences between methods for percentage time spent and distances covered performing different activities were 3.5% and 198.1 ± 138.1 m, respectively. Total number of changes in activity per 20 minutes were 184 ± 24 versus 458 ± 48, and work-to-rest ratios, 10.0%:90.0% and 7.3%:92.7% for notational and digitizing methods, respectively.

Conclusion:

The digitizing method is accurate and reliable for gaining detailed information on work profiles of field-sport participants and provides applied researchers richer data output than the conventional notational method.
Training Characteristics of Qualifiers for the U.S. Olympic Marathon Trials
Authors: Karp Jason R.
Published: August 2016

Purpose:

To describe and compare training characteristics of the 2004 U.S. Olympic Marathon Trials qualifiers.

Methods:

All qualifiers (104 men, 151 women) received questionnaires. Ninety-three (37 men, 56 women) responded and were categorized as elite (men <2 hours 15 minutes, women <2 hours 40 minutes) or national class.

Results:

Men and women ran 75% and 68% of their weekly training distance, respectively, below marathon race pace. Men trained longer than women (12.2 ± 5.3 vs 8.8 ± 5.6 years), ran more often (8.7 ± 2.8 vs 7.1 ± 2.5 times/wk), and ran farther (145.3 ± 25.6 vs 116.0 ± 26.5 km/wk). Elite women ran more than national-class women (135.8 ± 31.5 vs 111.3 ± 23.3 km/wk). Distances run at specific intensities were similar between sexes. For men and women, respectively, 49% and 31% did not have a coach and 65% and 68% trained alone. Marathon performance correlated to 5-km, 10-km, and half-marathon performance and to years training, average and peak weekly distance, number of weekly runs, and number of runs ≥32 km for women.

Conclusions:

Among U.S. Olympic Marathon Trials qualifiers, there is no consensus as to how to prepare for the marathon beyond running at a pace slower than race pace. Weekly training distance seems to influence women’s marathon performance more than it does men’s. Because many of these athletes train alone and without a coach, further research is warranted on the reasons that these athletes train the way they do.
Bicarbonate Loading to Enhance Training and Competitive Performance
Authors: Burke Louise M. , Pyne David B.
Published: August 2016

Bicarbonate loading is a popular ergogenic aid used primarily by athletes in short-duration, high-intensity sporting events and competitions. Controlled experimental trials have shown that small (worthwhile) benefits can obtained from acute doses of bicarbonate taken before exercise. Gastrointestinal problems encountered by some athletes limit the widespread use of this practice, however. The transfer of positive research findings to the competitive environment has proved problematic for some individuals. More recent applications involve serial ingestion of bicarbonate over several days before competition or during high-intensity training sessions over a few weeks. A number of research questions need to be addressed to enhance applications of bicarbonate loading in the elite sport environment. This commentary examines some of research and practical issues of bicarbonate loading used to enhance both training and competitive performance.
Responses of Motor-Sport Athletes to V8 Supercar Racing in Hot Conditions
Authors: Brearley Matt B. , Finn James P.
Published: August 2016

Background:

Despite the thermal challenge of demanding workloads performed in high cabin temperatures while wearing heavy heat-retardant clothing, information on physiological responses to racing V8 Supercars in hot conditions is not readily available.

Purpose:

To describe the thermal, cardiovascular, and perceptual strain on V8 Supercar drivers competing in hot conditions.

Methods:

Thermal strain was indicated by body-core temperature using an ingested thermosensitive pill. Cardiovascular strain was assessed from heart rate, hydration status, and sweat rate. Perceptual strain was estimated from self-rated thermal sensation, thermal discomfort (modified Gagge scales), perceived exertion (Borg scale), and perceptual strain index.

Results:

Prerace body-core temperatures were (mean ± SD) 37.7°C ± 0.4°C (range 37.0°C to 38.2°C), rising to 39.0°C ± 0.4°C (range 38.4°C to 39.7°C) postrace. Driver heart rates were >160 and >170 beats/min for 85.3% and 46.7% of racing, respectively. Sweat rates were 1.06 ± 0.12 L/h or 13.4 ± 1.2 mL · kg−1 · h−1, and postrace dehydration was 0.6% ± 0.6% of prerace body mass. Drivers rated thermal sensation as hot (10.3 ± 0.9), thermal discomfort as uncomfortable (3.1 ± 1.0), and perceived exertion as very hard to very, very hard (8.7 ± 1.7) after the races. Overall physiological and perceptual strain were 7.4 ± 1.0 and 7.1 ± 1.2, respectively.

Conclusions:

Despite the use of cooling, V8 Supercar drivers endure thermal, cardiovascular, and perceptual strain during brief driving bouts in hot conditions.
The Use of Static Stretching in Warm-Up for Training and Competition
Authors: Young Warren B.
Published: August 2016

Static stretching (SS) is widely used in warm-ups before training and competition. A growing amount of research, however, has demonstrated that SS can impair muscle performance, leading to a reevaluation of optimal warm-up protocols. This commentary discusses many of the methodological issues that can influence conclusions about the acute effects of SS on performance. One difficulty in interpreting the literature is the lack of control or communication about the volume and intensity of the various stretching treatments used. Another major issue is the failure of many researchers to evaluate SS as it is used in practice, particularly the interaction with the other general and sport-specific components of the warm-up. Acute warm-up effects on performance should be considered in conjunction with potential effects on injury prevention. Future directions in research include optimizing general and sport-specific warm-ups, time course of physiological and performance effects, and individualization of warm-ups according to fitness and skill level.
Multiple-Sprint Work: Methodological, Physiological, and Experimental Issues
Authors: Glaister Mark
Published: August 2016

Tests of repeated-sprint ability provide a simple way to evaluate the basic physical characteristics of speed and endurance necessary to excel in various multiple-sprint sports. Furthermore, such tests help overcome the complications associated with field-based evaluations of this type of exercise. Nevertheless, despite over 40 y of research, many issues regarding our understanding of multiple-sprint work remain unresolved. This commentary aims to raise awareness of issues relating to methodology, physiological responses, and the effectiveness of various ergogenic and training strategies; to promote a greater understanding; and to drive future research.
Quantifying Training Load: A Comparison of Subjective and Objective Methods
Authors: Borresen Jill , Lambert Michael I.
Published: August 2016

Purpose:

To establish the relationship between a subjective (session rating of perceived exertion [RPE]) and 2 objective (training impulse [TRIMP]) and summated-heart-rate-zone (SHRZ) methods of quantifying training load and explain characteristics of the variance not accounted for in these relationships.

Methods:

Thirty-three participants trained ad libitum for 2 wk, and their heart rate (HR) and RPE were recorded to calculate training load. Subjects were divided into groups based on whether the regression equations over- (OVER), under- (UNDER), or accurately predicted (ACCURATE) the relationship between objective and subjective methods.

Results:

A correlation of r = .76 (95% CI: .56 to .88) occurred between TRIMP and session-RPE training load. OVER spent a greater percentage of training time in zone 4 of SHRZ (ie, 80% to 90% HRmax) than UNDER (46% ± 8% vs 25% ± 10% [mean ± SD], P = .008). UNDER spent a greater percentage of training time in zone 1 of SHRZ (ie, 50% to 60% HRmax) than OVER (15% ± 8% vs 3% ± 3%, P = .005) and ACCURATE (5% ± 3%, P = .020) and more time in zone 2 of SHRZ (ie, 60% to 70%HRmax) than OVER (17% ± 6% vs 7% ± 6%, P = .039). A correlation of r = .84 (.70 to .92) occurred between SHRZ and session-RPE training load. OVER spent proportionally more time in Zone 4 than UNDER (45% ± 8% vs 25% ± 10%, P = .018). UNDER had a lower training HR than ACCURATE (132 ± 10 vs 148 ± 12 beats/min, P = .048) and spent more time in zone 1 than OVER (15% ± 8% vs 4% ± 3%, P = .013) and ACCURATE (5% ± 3%, P = .015).

Conclusions:

The session-RPE method provides reasonably accurate assessments of training load compared with HR-based methods, but they deviate in accuracy when proportionally more time is spent training at low or high intensity.
The Effects of Caffeine Ingestion on Time Trial Cycling Performance
Authors: McNaughton L.R. , Lovell R.J. , Siegler J. , Midgley A.W. , Moore L. , Bentley D.J.
Published: August 2016

Purpose:

The purpose of this work was to determine the effects of caffeine on high intensity time trial (TT) cycling performance in well-trained subjects.

Subjects:

Six male cyclists with the following physical characteristics (mean ± SD) age 30.7 ± 12, height 179.3 ± 7.5 cm, mass 70.0 ± 7.5 kg, VO2max 65.0 ± 6.3 mL·kg−1·min−1 undertook three 1-h TT performances, control (C), placebo (P) and caffeine (CAF), on a Velotron cycle ergometer conducted in a double-blind, random fashion. Subjects rested for 60 min and were then given CAF or P in a dose of 6 mg·kg−1 body mass and then commenced exercise after another 60 min of rest. Before ingestion, 60 min postingestion, and at the end of the TT, finger-prick blood samples were analyzed for lactate.

Results:

The cyclists rode significantly further in the CAF trial (28.0 ± 1.3 km) than they did in the C (26.3 ± 1.5 km, P < .01) or P (26.4 ± 1.5 km, P < .02) trials. No differences were seen in heart rate data throughout the TT (P > .05). Blood lactate levels were significantly higher at the end of the trials than either at rest or postingestion (P < .0001), but there were no differences between the three trial groups.

Conclusion:

On the basis of the data, we concluded that performance was improved with the use of a caffeine supplement.
Time Course of Blood Bicarbonate and pH Three Hours After Sodium Bicarbonate Ingestion
Authors: Price Michael J. , Singh Malkit
Published: August 2016

This study examined the increase in blood pH and bicarbonate concentration after ingestion of a standard sodium bicarbonate solution. Peak blood pH and bicarbonate concentration occurred between 60 and 90 minutes. Values decreased over the remainder of the ingestion period although still elevated above preingestion levels.
Performance Profiling: A Role for Sport Science in the Fight Against Doping?
Authors: Schumacher Yorck Olaf , Pottgiesser Torben
Published: August 2016

In recent years, antidoping strategies underwent a significant development, from purely biochemical analyses and the detection of substances in urine samples to a biological approach, using blood samples, longitudinal monitoring, and probabilistic techniques. Nowadays, the appropriate timing of testing and the targeting of the athletes to be tested with antidoping tests is a major issue. A new strategy to improve the targeting of suspicious athletes might be the longitudinal monitoring of individual performances. By these means, suspect athletes might be identified, as doping will not only alter their blood or steroid profles, but ultimately boost their performance, as well. Through the proposed approach, the effectiveness in the fight against doping might be improved considerably.
Validity of a Squash-Specific Fitness Test
Authors: Wilkinson Michael , Leedale-Brown Damon , Winter Edward M.
Published: August 2016

Purpose:

This study examined the validity of a squash-specific test designed to assess endurance capability and aerobic power.

Methods:

Eight squash players and eight runners performed, in a counterbalanced order, incremental treadmill (TT) and squash-specific (ST) tests to volitional exhaustion. Breath-by-breath oxygen uptake was determined by a portable analyzer and heart rate was assessed telemetrically. Time to exhaustion was recorded.

Results:

Independent t tests revealed longer time to exhaustion for squash players on the ST than runners (775 ± 103 vs. 607 ± 81 s; P = .003) but no difference between squash players and runners in maximal oxygen uptake ( Vo2max) or maximum heart rate (HRmax). Runners exercised longer on the TT (521 ± 135 vs. 343 ± 115 s; P = .01) and achieved higher Vo2max than squash players (58.6 ± 7.5 vs. 49.6 ± 7.3 mL·kg−1·min−1; P = .03), with no group difference in HRmax. Paired t tests showed squash players achieved higher Vo2max on the ST than the TT (52.2 ± 7.1 vs. 49.6 ± 7.3 mL·kg−1·min−1; P = .02). The Vo2max and HRmax of runners did not differ between tests, nor did the HRmax of squash players. ST and TT Vo2max correlated highly in squash players and runners (r = .94, P < .001; r = .88, P = .003).

Conclusions:

The ST discriminated endurance performance between squash players and runners and elicited higher Vo2max in squash players than a nonspecifc test. The results suggest that the ST is a valid assessment of Vo2max and endurance capability in squash players.
Effect of Surface Stability on Core Muscle Activity for Dynamic Resistance Exercises
Authors: Willardson Jeffrey M. , Fontana Fabio E. , Bressel Eadric
Published: August 2016

Purpose:

To compare core muscle activity during resistance exercises performed on stable ground vs. the BOSU Balance Trainer.

Methods:

Twelve trained men performed the back squat, dead lift, overhead press, and curl lifts. The activity of the rectus abdominis, external oblique abdominis, transversus abdominis/internal oblique abdominis, and erector spinae muscles was assessed. Subjects performed each lift under three separate conditions including standing on stable ground with 50% of a 1-RM, standing on a BOSU Balance Trainer with 50% of a 1-RM, and standing on stable ground with 75% of a 1-RM.

Results:

Significant differences were noted between the stable 75% of 1-RM and BOSU 50% of 1-RM conditions for the rectus abdominis during the overhead press and transversus abdominis/internal oblique abdominis during the overhead press and curl (P < .05). Conversely, there were no significant differences between the stable 75% of 1-RM and BOSU 50% of 1-RM conditions for the external obliques and erector spinae across all lifts examined. Furthermore, there were no significant differences between the BOSU 50% of 1-RM and stable 50% of 1-RM conditions across all muscles and lifts examined.

Conclusions:

The current study did not demonstrate any advantage in utilizing the BOSU Balance Trainer. Therefore, fitness trainers should be advised that each of the aforementioned lifts can be performed while standing on stable ground without losing the potential core muscle training benefits.
Test Validation in Sport Physiology: Lessons Learned From Clinimetrics
Authors: Impellizzeri Franco M. , Marcora Samuele M.
Published: August 2016

We propose that physiological and performance tests used in sport science research and professional practice should be developed following a rigorous validation process, as is done in other scientific fields, such as clinimetrics, an area of research that focuses on the quality of clinical measurement and uses methods derived from psychometrics. In this commentary, we briefly review some of the attributes that must be explored when validating a test: the conceptual model, validity, reliability, and responsiveness. Examples from the sport science literature are provided.
The Effects of Low– and High–Glycemic Index Meals on Time Trial Performance
Authors: Moore Laura J.S. , Midgley Adrian W. , Thomas Gemma , Thurlow Shane , McNaughton Lars R.
Published: August 2016

Purpose:

The aim of this work was to determine whether the consumption of pre-exercise high– or low–glycemic index (GI) meals has a beneficial effect on time trial performance.

Methods:

Eight male cyclists were provided with either a high-GI or low-GI meal, providing 1 g·kg−1 body mass of carbohydrate, 45 min before performing a 40-km time trial on a Velotron cyclePro.

Results:

Time trial performance was significantly improved in the low-GI trial (92.5 ± 5.2 min) compared with the high-GI trial (95.6 ± 6.0 min) (P = .009). Blood glucose concentrations at the point of exhaustion were significantly higher in the low-GI trial (5.2± 0.6 mmol·L−1) compared with the high-GI trial (4.7 ± 0.7 mmol·L−1) (P = .001). There was no significant difference in estimated carbohydrate oxidation data between the low-GI (2.51 ± 1.74 g·min−1) and high-GI (2.18 ± 1.53 g·min−1) meals (P = .195). No significant difference in estimated fat oxidation was observed between the low-GI (0.15 ± 0.15 g·min−1) and high-GI (0.29 ± 0.18 g·min−1) diets (P = .83).

Conclusions:

The improvement in time trial performance for the low-GI trial may be associated with an increased availability of glucose to the working muscles, contributing additional carbohydrate for oxidation and possibly sparing limited muscle and liver glycogen stores.
Baseball-Specific Conditioning
Authors: Rhea Matthew R. , Bunker Derek
Published: August 2016

Baseball demands speed, power, and quickness. To perform at a high level, and avoid injuries that are common among baseball players, an evaluation of current trends in strength and conditioning practices is helpful. Based on the demands of the sport and the injury risks, qualified strength and conditioning professionals can develop effective baseball-specific conditioning programs. This commentary briefly covers historical aspects of baseball conditioning, recent injury trends, current practices among elite baseball professionals, and provides suggestions for future improvements in training.