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S.J. Hanrahan, Howard K. Hall, Jim Taylor and Mark A. Thompson
Edited by J. Robert Grove
Kevin L. Burke, Vikki Krane, Jim Taylor, Mark A. Thompson and James P. Whelan
Edited by J. Robert Grove
Janet Buckworth, Howard K. Hall, Stephanie H. Hanrahan, Cathy Lirgg, Michelle Paccagnella, Jim Taylor and Mark A. Thompson
Edited by J. Robert Grove
Vicki Ebbeck, Jim Taylor, Mark A. Thompson, Kevin L. Burke, Vikki Krane and Howard K. Hall
Edited by Charles J. Hardy
Andrew J.R. Cochran, Michael E. Percival, Sara Thompson, Jenna B. Gillen, Martin J. MacInnis, Murray A. Potter, Mark A. Tarnopolsky and Martin J. Gibala
Sprint interval training (SIT), repeated bouts of high-intensity exercise, improves skeletal muscle oxidative capacity and exercise performance. β-alanine (β-ALA) supplementation has been shown to enhance exercise performance, which led us to hypothesize that chronic β-ALA supplementation would augment work capacity during SIT and augment training-induced adaptations in skeletal muscle and performance. Twenty-four active but untrained men (23 ± 2 yr; VO2peak = 50 ± 6 mL·kg−1·min−1) ingested 3.2 g/day of β-ALA or a placebo (PLA) for a total of 10 weeks (n = 12 per group). Following 4 weeks of baseline supplementation, participants completed a 6-week SIT intervention. Each of 3 weekly sessions consisted of 4–6 Wingate tests, i.e., 30-s bouts of maximal cycling, interspersed with 4 min of recovery. Before and after the 6-week SIT program, participants completed a 250-kJ time trial and a repeated sprint test. Biopsies (v. lateralis) revealed that skeletal muscle carnosine content increased by 33% and 52%, respectively, after 4 and 10 weeks of β-ALA supplementation, but was unchanged in PLA. Total work performed during each training session was similar across treatments. SIT increased markers of mitochondrial content, including cytochome c oxidase (40%) and β-hydroxyacyl-CoA dehydrogenase maximal activities (19%), as well as VO2peak (9%), repeated-sprint capacity (5%), and 250-kJ time trial performance (13%), but there were no differences between treatments for any measure (p < .01, main effects for time; p > .05, interaction effects). The training stimulus may have overwhelmed any potential influence of β-ALA, or the supplementation protocol was insufficient to alter the variables to a detectable extent.
David Feeny, Rochelle Garner, Julie Bernier, Amanda Thompson, Bentson H. McFarland, Nathalie Huguet, Mark S. Kaplan, Nancy A. Ross and Chris M. Blanchard
Background:
The objective of this study was to assess the associations among body mass index (BMI), leisure time physical activity (LTPA) and health-related quality of life (HRQL) trajectories among adults.
Methods:
Self-reported data were drawn from the Canadian National Population Health Survey, with respondents being interviewed every 2 years between 1996–97 and 2006–07. Using growth curve modeling, HRQL trajectories for individuals aged 18 and over were associated with measures of BMI and LTPA. Growth models were constructed separately for males and females.
Results:
Findings suggested that, for males, BMI categories had little impact on baseline HRQL, and no impact on the rate of change in HRQL. Among women, higher BMI categories were associated with significantly lower baseline HRQL. However, BMI had no impact on the rate of change of HRQL. Conversely, for both men and women and regardless of BMI category, LTPA had significant impacts on baseline HRQL, as well as the rate of change in HRQL. Individuals who were inactive or sedentary had much steeper declines in HRQL as they aged, as compared with individuals who were active in their leisure time.
Conclusions:
The results underscore the importance of LTPA in shaping trajectories of HRQL.
