Effect of creatine loading on long-term sprint exercise performance and metabolism

Author(s):  
DAVID PREEN ◽  
BRIAN DAWSON ◽  
CARMEL GOODMAN ◽  
STEVEN LAWRENCE ◽  
JOHN BEILBY ◽  
...  
Author(s):  
Joana M. Correia ◽  
Inês Santos ◽  
Pedro Pezarat-Correia ◽  
Cláudia Minderico ◽  
Brad J. Schoenfeld ◽  
...  

Using a crossover design, we explored the effects of both short- and long-term time-restricted feeding (TRF) vs. regular diet on Wingate (WnT) performance and body composition in well-trained young men. Twelve healthy male physical education students were included (age: 22.4 ± 2.8 years, height: 174.0 ± 7.1 cm, body mass: 73.6 ± 9.5 kg, body mass index: 24.2 ± 2.0 kg/m2). The order of dieting was randomized and counterbalanced, and all participants served as their own controls. TRF was limited to an 8-h eating window and non-TRF involved a customary meal pattern. Participants performed WnT tests and body composition scans at baseline, post-one and post-four weeks of the assigned diet. Before testing, participants were asked to fill out a dietary record over four consecutive days and were instructed to continue their habitual training throughout the study. Energy intake and macronutrient distribution were similar at baseline in both conditions. WnT mean power and total work output increased post-four weeks of TRF. Both conditions were similarly effective in increasing fat-free mass after four weeks of intervention. However, there was no correlation between change in fat-free mass and WnT mean power after TRF. TRF did not elicit any changes in WnT performance or body composition one week post-intervention. Thus, long-term TRF can be used in combination with regular training to improve supramaximal exercise performance in well-trained men.


2011 ◽  
Vol 165 (2) ◽  
pp. 243-248 ◽  
Author(s):  
Henna Cederberg ◽  
Ulla Rajala ◽  
Vesa-Matti Koivisto ◽  
Jari Jokelainen ◽  
Heljä-Marja Surcel ◽  
...  

ObjectiveGhrelin, a gut–brain peptide involved in energy homeostasis, circulates predominantly (>90%) in unacylated form. Previous studies, however, have focused on total and acylated ghrelin, and the role of unacylated ghrelin (UAG) is not well understood. Particularly, the association of UAG with weight loss and changes in body composition in adults remains unclear. We hypothesized that exercise-associated increase in UAG level is associated with weight loss, favorable changes in body composition, and body fat distribution.Design and methodsA prospective study of 552 young men (mean age 19.3 and range 19–28 years) undergoing military service with structured 6-month exercise training program. Exercise performance, body composition, and biochemical measurements were obtained at baseline and follow-up. Association between changes in UAG levels and body composition and body fat distribution were evaluated.ResultsAn increase in UAG level during the exercise intervention was associated with reduced weight, fat mass (FM), fat percentage (fat %), and waist circumference, but not with fat-free mass. Inverse associations of changes in UAG level with changes in waist circumference and fat % were independent of weight at baseline, and changes in weight and exercise performance. Associations of changes in UAG level with waist circumference were significantly stronger than with fat % after the adjustment for confounding variables.ConclusionUAG is associated with changes in body weight and body composition during an intensive long-term exercise intervention in young men. The association of UAG levels with changes in central obesity was stronger than with total FM.


2012 ◽  
Vol 40 (3) ◽  
pp. 174-182 ◽  
Author(s):  
Matthew W. Bundle ◽  
Peter G. Weyand

2014 ◽  
Vol 9 (3) ◽  
pp. 387-396 ◽  
Author(s):  
Mark Hayes ◽  
Paul C. Castle ◽  
Emma Z. Ross ◽  
Neil S. Maxwell

Purpose:To examine the effect of a hot humid (HH) compared with a hot dry (HD) environment, matched for heat stress, on intermittent-sprint performance. In comparison with HD, HH environments compromise evaporative heat loss and decrease exercise tolerance. It was hypothesized that HH would produce greater physiological strain and reduce intermittent-sprint exercise performance compared with HD.Method:Eleven male team-sport players completed the cycling intermittent-sprint protocol (CISP) in 3 conditions, temperate (TEMP; 21.2°C ± 1.3°C, 48.6% ± 8.4% relative humidity [rh]), HH (33.7°C ± 0.5°C, 78.2% ± 2.3% rh), and HD (40.2°C ± 0.2°C, 33.1% ± 4.9% rh), with both heat conditions matched for heat stress.Results:All participants completed the CISP in TEMP, but 3 failed to completed the full protocol of 20 sprints in HH and HD. Peak power output declined in all conditions (P < .05) but was not different between any condition (sprints 1–14 [N = 11]: HH 1073 ± 150 W, HD 1104 ± 127 W, TEMP, 1074 ± 134; sprints 15–20 [N = 8]: HH 954 ± 114 W, HD 997 ± 115 W, TEMP 993 ± 94; P > .05). Physiological strain was not significantly different in HH compared with HD, but HH was higher than TEMP (P < .05).Conclusion:Intermittent-sprint exercise performance of 40 min duration is impaired, but it is not different in HH and HD environments matched for heat stress despite evidence of a trend toward greater physiological strain in an HH environment.


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