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Changes of time course of sarcoplasmic reticulum CA2+ uptake and release in red and white vastus muscles after eccentric exercise
Performance changes by triathletes competing in their second successive ultra distance triathlon G. Dickson 1, & G. Schofield 1, 1Central Queensland University 2Auckland University of Technology
The purpose of this research was to identify performance changes by triathletes competing in their second successive ultra distance triathlon (UDT). Ultra-distance triathlon consists of a sequential 3.8km swim, 180km bike and a 42km run. Discussion within the triathlon community regarding the likelihood of UDT participants being able to exceed their debut performance levels in the year following their debut has been anecdotal and without empirical support. Triathletes (n=326) who competed in their first Ironman Australia in either 1999 or 2002 were compared to their subsequent performances in 2000 and 2003 using standard (Z) scores for the swim, bike, run disciplines as well as overall performance. Results indicated that 64% improved their swim performance, 71% improved their bike performance, 59% improved their run performance and 79% of triathletes improved their performance overall. Significant gender differences were identified (X 2 =24.5, p<.01). Females (31%) were more likely have a decline in relative overall performance compared to males (9%). No significant differences between professional category triathletes, athletes over 40 years of age and under 40 years age were identified. The findings of this descriptive study indicate that further research should be conducted to investigate the biomechanical, physiological, and psychological explanations of why female triathletes are less likely to improve.
Changes of time course of sarcoplasmic reticulum CA2+ uptake and release in red and white vastus muscles after eccentric exercise W. Chen 1, p. Rueil 1, H. Westra 2, K. Hoffman 1 & M. Thompson 1. 1School Of Exercise & Sport Science, The University Of Sydney 2Vrije UniversiteitAmsterdam, The Netherlands
We investigated the hypothesis that eccentric exercise would cause modifications of both SR CA2÷ uptake and release in rat muscle. Adult male SD rats were randomly assigned to control and eccentric exercise (ECE) groups. The ECE rats were subdivided into one of six groups studied at 0, 4, 24, 48, 72 and 144 h after ECE (n=7). The exercise protocol consisted of a 90min continuous downhill walking (-16°, 15 m/min). Red vastus (RV) and white vastus (WV) muscles were sampled separately and muscle homogenates were prepared. CA2+ uptake and release rates were measured in vitro. In RV, CA2÷ uptake was lower (P<0.05) compared with Control, by 29, 36, and 19% at 0, 4, and 24h, respectively, and remained depressed at 48h by 14% (P>0.05). CA2+ release was also lower (P<0.05), by 37, 39, and 25% at 0, 4, and 24h, respectively, and remained depressed at 48h by 13% (P>0.05). However, in WV, CA2÷ uptake decreased (P<0.05) by 26% at 4h only, although decrease at Oh by 16% (P>0.05); While CA2÷ release showed a non-significant decrease (P>0.05) by 17% at 4h, no significant changes were found at other time points. Significant reductions of both SR CA2÷ uptake and release rates were observed in RV, at 0, 4, and 24h, and these reductions had not totally recovered until 48h. This may be attributed to the low recruitment threshold and relatively important postural roles of these slow motor units. However, similar modifications of CA2÷ uptake and release in WV were not detected.
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The purpose of this research was to identify performance changes by triathletes competing in their second successive ultra distance triathlon (UDT). Ultra-distance triathlon consists of a sequential 3.8km swim, 180km bike and a 42km run. Discussion within the triathlon community regarding the likelihood of UDT participants being able to exceed their debut performance levels in the year following their debut has been anecdotal and without empirical support. Triathletes (n=326) who competed in their first Ironman Australia in either 1999 or 2002 were compared to their subsequent performances in 2000 and 2003 using standard (Z) scores for the swim, bike, run disciplines as well as overall performance. Results indicated that 64% improved their swim performance, 71% improved their bike performance, 59% improved their run performance and 79% of triathletes improved their performance overall. Significant gender differences were identified (X 2 =24.5, p<.01). Females (31%) were more likely have a decline in relative overall performance compared to males (9%). No significant differences between professional category triathletes, athletes over 40 years of age and under 40 years age were identified. The findings of this descriptive study indicate that further research should be conducted to investigate the biomechanical, physiological, and psychological explanations of why female triathletes are less likely to improve.
Changes of time course of sarcoplasmic reticulum CA2+ uptake and release in red and white vastus muscles after eccentric exercise W. Chen 1, p. Rueil 1, H. Westra 2, K. Hoffman 1 & M. Thompson 1. 1School Of Exercise & Sport Science, The University Of Sydney 2Vrije UniversiteitAmsterdam, The Netherlands
We investigated the hypothesis that eccentric exercise would cause modifications of both SR CA2÷ uptake and release in rat muscle. Adult male SD rats were randomly assigned to control and eccentric exercise (ECE) groups. The ECE rats were subdivided into one of six groups studied at 0, 4, 24, 48, 72 and 144 h after ECE (n=7). The exercise protocol consisted of a 90min continuous downhill walking (-16°, 15 m/min). Red vastus (RV) and white vastus (WV) muscles were sampled separately and muscle homogenates were prepared. CA2+ uptake and release rates were measured in vitro. In RV, CA2÷ uptake was lower (P<0.05) compared with Control, by 29, 36, and 19% at 0, 4, and 24h, respectively, and remained depressed at 48h by 14% (P>0.05). CA2+ release was also lower (P<0.05), by 37, 39, and 25% at 0, 4, and 24h, respectively, and remained depressed at 48h by 13% (P>0.05). However, in WV, CA2÷ uptake decreased (P<0.05) by 26% at 4h only, although decrease at Oh by 16% (P>0.05); While CA2÷ release showed a non-significant decrease (P>0.05) by 17% at 4h, no significant changes were found at other time points. Significant reductions of both SR CA2÷ uptake and release rates were observed in RV, at 0, 4, and 24h, and these reductions had not totally recovered until 48h. This may be attributed to the low recruitment threshold and relatively important postural roles of these slow motor units. However, similar modifications of CA2÷ uptake and release in WV were not detected.
526