It is well established that adequate bodily carbohydrate reserves are required for optimal endurance. Based on this fact, it has been hypothesized that consumption of a diet with a high percentage of carbohydrate energy will optimize training adaptations and athletic performance. Scrutiny of the literature, however, does not strongly support the hypothesis that short-term or long-term reductions in dietary carbohydrate energy impairs training or athletic performance. Additional studies with well devised training protocols and performance tests are necessary to prove or disprove the hypothesis that a high carbohydrate energy diet is necessary to optimize training adaptations and performance. Because dietary carbohydrate contributes directly to bodily carbohydrate reserves, and because a high carbohydrate energy diet does not impair athletic performance, it remains prudent to advise athletes to consume a diet with a high carbohydrate energy content.
William M. Sherman and Gregory S. Wimer
Øystein N. Wiggen, Cecilie T. Heidelberg, Silje H. Waagaard, Hilde Færevik and Øyvind Sandbakk
To investigate differences in double-poling (DP) endurance performance, economy, and peak oxygen uptake (V̇O2peak) at low (–15°C) and moderate (6°C) ambient temperatures (T A) in cross-country skiers wearing standard racing suits.
Thirteen well-trained male cross-country skiers performed a standardized warm-up followed by a 5-min submaximal test (Sub1), a 20-min self-paced performance test, a 2nd 5-min submaximal test (Sub2), and an incremental test to exhaustion while DP on an ergometer at either low or moderate T A, randomized on 2 different days. Skin and rectal temperatures, as well as power output and respiratory variables, were measured continuously during all tests.
Skin and rectal temperatures were more reduced at low T A than moderate TA (both P < .05). There was a 5% (P < .05) lower average power output during the 20-min performance test at low T A than at moderate T A, which primarily occurred in the first 8 min of the test (P < .05). Although DP economy decreased from Sub1 to Sub2 for both T As (both P < .01), a 3.7% (P < .01) larger decrease in DP economy from Sub1 to Sub2 emerged for the low T A. Across the sample, V̇O2peak was independent of T A.
These results demonstrate a lower body temperature and reduced performance for cross-country skiers when DP at low than at moderate TA while wearing standard cross-country-skiing racing suits. Lower DP performance at the low T A was mainly due to lower power production during the first part of the test and coincided with reduced DP economy.
Simon P. Roberts, Keith A. Stokes, Lee Weston and Grant Trewartha
This study presents an exercise protocol utilizing movement patterns specific to rugby union forward and assesses the reproducibility of scores from this test.
After habituation, eight participants (mean ± SD: age = 21 ± 3 y, height = 180 ± 4 cm, body mass = 83.9 ± 3.9 kg) performed the Bath University Rugby Shuttle Test (BURST) on two occasions, 1 wk apart. The protocol comprised 16 × 315-s cycles (4 × 21-min blocks) of 20-m shuttles of walking and cruising with 10-m jogs, with simulated scrummaging, rucking, or mauling exercises and standing rests. In the last minute of every 315-s cycle, a timed Performance Test was carried out, involving carrying a tackle bag and an agility sprint with a ball, followed by a 25-s recovery and a 15-m sprint.
Participants traveled 7078 m, spending 79.8 and 20.2% of time in low- and high-intensity activity, respectively. The coefficients of variation (CV) between trials 1 and 2 for mean time on the Performance Test (17.78 ± 0.71 vs 17.58 ± 0.79 s) and 15-m sprint (2.69 ± 0.15 vs 2.69 ± 0.15 s) were 1.3 and 0.9%, respectively. There was a CV of 2.2% between trials 1 and 2 for mean heart rate (160 ± 5 vs 158 ± 5 beats⋅min−1) and 14.4% for blood lactate (4.41 ± 1.22 vs 4.68 ± 1.68 mmol⋅L−1).
Results suggest that measures of rugby union-specifc high-intensity exercise performed during the BURST were reproducible over two trials in habituated participants.
Catalina Fernández-Campos, Ana L. Dengo and José Moncada-Jiménez
To determine the acute effect of an energy drink (ED) on physical performance of professional female volleyball players. 19 females (age= 22.3 ± 4.9 yr.; height= 171.8 ± 9.4 cm; weight= 65.2 ± 10.1 kg) participated in a randomized, crossover, double-blind study to measure grip strength, vertical jump and anaerobic power in 3 different sessions (ED, placebo [PL] or no beverage [CTL]). For each session, participants arrived in a fasted state, consumed a standardized breakfast meal, and 1 hr later completed the 3 baseline performance tests without having ingested the beverage. After completing the premeasurements, the athletes drank 6 ml/kg of body weight of the ED or PL and in the CTL condition no beverage was consumed. Posttest measurements were taken 30 min after the ingestion of liquids. A 3 × 2 repeated-measures ANOVA revealed no significant within-session and measurement time interactions for each performance test. Regardless of the measurement time, right hand grip strength was significantly higher in the ED condition (34.6 ± 0.9 kg) compared with PL (33.4 ± 1.1 kg) and CTL (33.6 ± 1.0 kg) (p > 0.05). Regardless of the beverage ingested, averaged right hand grip strength, taking into account all 3 testing conditions, increased from pre to posttesting (Pre = 33.8 ± 0.9 kg vs. Post = 33.9 ± 1.0 kg; p = 0.029), as did the averaged fatigue index, obtained from the anaerobic power test (Pre = 65.9± 2.2% vs. Post = 68.7± 2.0%; p= 0.049). The acute ingestion of an ED did not improve physical performance of professional Costa Rican female volleyball players.
Ching-Yi Wang, Ming-Hsia Hu, Hui-Ya Chen and Ren-Hau Li
To determine the test–retest reliability and criterion validity of self-reported function in mobility and instrumental activities of daily living (IADL) in older adults, a convenience sample of 70 subjects (72.9 ± 6.6 yr, 34 male) was split into able and disabled groups based on baseline assessment and into consistently able, consistently disabled, and inconsistent based on repeat assessments over 2 weeks. The criterion validities of the self-reported measures of mobility domain and IADL-physical subdomain were assessed with concurrent baseline measures of 4 mobility performances, and that of the self-reported measure of IADL-cognitive subdomain, with the Mini-Mental State Examination. Test–retest reliability was moderate for the mobility, IADL-physical, and IADL-cognitive subdomains (κ = .51–.66). Those who reported being able at baseline also performed better on physical- and cognitive-performance tests. Those with variable performance between test occasions tended to report inconsistently on repeat measures in mobility and IADL-cognitive, suggesting fluctuations in physical and cognitive performance.
Andrew M. Edwards and Raewyn E. Walker
The efficacy of inspiratory muscle training (IMT) has been the subject of considerable controversy in terms of whether it is beneficial to endurance athletes and because a convincing physiological rationale has not been identified to explain its mechanism of action. Early studies suggested that IMT was an ineffectual intervention for gains in either maximal aerobic power or endurance-specific performance. More rigorous recent research supports the observation that maximal aerobic power is not receptive to IMT; however, closer evaluation of both early and contemporary research indicates that responses to endurance-specific performance tests are sensitive to IMT. As the aim of endurance training is to improve endurance performance rather than maximal aerobic power, it is plausible that IMT may be useful in specific performance-related circumstances. Performance adaptations following IMT appear to be connected with post training reports of attenuated effort sensations, but this common observation has tended to be overlooked by researchers in preference for a reductionist explanation. This commentary examines the pertinent research and practical performance implications of IMT from the holistic perspective of complex central metabolic control.
Bruce A. Reeder, Karen E. Chad, Elizabeth L. Harrison, Nigel L. Ashworth, M. Suzanne Sheppard, Koren L. Fisher, Brenda G. Bruner, Brian G. Quinn, Punam Pahwa and M. Alomgir Hossain
The study aimed to compare the effectiveness of a class-based (CB) and home-based (HB) exercise program for older adults with chronic health conditions.
172 sedentary older adults with overweight or obesity, type 2 diabetes, hypertension, dyslipidemia, or osteoarthritis were enrolled in a randomized controlled trial with a 3-month follow-up.
A significant increase was seen in the CB group in the Physical Activity Scale for the Elderly (PASE) scores and SF-12 Physical and Mental Health scores. In both groups, significant increases were seen in 6-minute walk distance, Physical Performance Test (PPT), and Functional Fitness Test (FFT), and significant reductions were seen in systolic and diastolic blood pressure but not body mass index or waist circumference. Except for a greater increment in the FFT in the CB group, the degree of improvement was not significantly different between the 2 groups.
After a 3-month intervention, both the CB and HB program produced comparable significant improvements in outcome measures.
David S. Rowlands, Rhys M. Thorp, Karin Rossler, David F. Graham and Mike J. Rockell
Carbohydrate ingestion after prolonged strenuous exercise enhances recovery, but protein might also be important. In a crossover with 2-wk washout, 10 cyclists completed 2.5 h of intervals followed by 4-h recovery feeding, provided 218 g protein, 435 g carbohydrate, and 79 g fat (protein enriched) or 34 g protein, 640 g carbohydrate, and 79 g fat (isocaloric control). The next morning, cyclists performed 10 maximal constant-work sprints on a Velotron cycle ergometer, each lasting ~2.5 min, at ~5-min intervals. Test validity was established and test reliability and the individual response to the protein-enriched condition estimated by 6 cyclists’ repeating the intervals, recovery feeding, and performance test 2 wk later in the protein-enriched condition. During the 4-h recovery, the protein-enriched feeding had unclear effects on mean concentrations of plasma insulin, cortisol, and growth hormone, but testosterone was 25% higher (90% confidence limits, ± 14%). Protein enrichment also reduced plasma creatine kinase by 33% (±38%) the next morning and reduced tiredness and leg-soreness sensations during the sprints, but effects on mean sprint power were unclear (–1.4%, ±4.3%). The between-subjects trial-to-trial coefficient of variation in overall mean sprint power was 3.1% (±3.4%), whereas the variation in the protein-enriched condition was 5.9% (±6.9%), suggesting that individual responses to the protein-enriched treatment contributed to the unclear performance outcome. To conclude, protein-enriched recovery feeding had no clear effect on next-day performance.
Daniel M. Landers, Shawn M. Arent and Rafer S. Lutz
Recent research has demonstrated transient affective changes and impairment of short-term memory in college wrestlers as a result of rapid weight loss (RWL) of at least 5% body weight prior to competition. This study examined the effects of RWL on cognition and affect in high school wrestlers. Wrestlers were considered to be engaging in RWL if they were losing over 5% of body weight (n = 14). Those losing less than 1% of body weight (n = 14) were considered maintainers and served as the control group. Both groups were given a battery of tests assessing cognitive performance (Trail Making Tests A & B, Stroop color-word test, Wechsler digit span, and choice reaction/movement time) and affective state (PANAS) at normal weight (5 to 10 days prior to competition) and again 8 to 12 hours prior to weigh-in. Results indicated an average loss of 4.68 kg in the RWL group and 0.29 kg in the control group. A group-by-time MANOVA and univariate follow-up tests indicated a significant group-by-time interaction for positive affect, p < .014, with the RWL wrestlers having less positive affect than the control group just prior to weigh-in. However, none of the cognitive performance tests demonstrated significant differential changes for RWL vs. control groups, p > .10. Given the control for competition effects in the present study, results suggest there are affective disturbances, but not cognitive impairments, associated with RWL of at least 5% body weight in high school wrestlers.
Bryan L. Riemann, Nancy A. Caggiano and Scott M. Lephart
Postural control and functional performance tests are often used separately during orthopedic postinjury assessments. The purpose of this investigation was to examine a clinical method of assessing postural control during a functional performance task. Thirty participants were divided into two groups. The first group was tested three times, the second group only once. The same tester evaluated each participant's performance during all testing sessions, and during the first two testing sessions (Group 1) two additional testers evaluated each performance. Intraclass correlational coefficients between the three testers ranged from .70 to .92. Session 1 (Group 1) scores were pooled with Group 2 scores, and correlational analyses were conducted between participant height and performance; no significant relationships were revealed. The scores from Group 1 were analyzed using between-days repeated-measures ANOVAs. Results revealed significant improvement between Sessions 1 and 3 for the static portion of the test. The results suggest that the multiple single-leg hop-stabilization test offers a method of assessing postural control during a functional performance task.