Abstract
<p>Athletic performance relies heavily on the rate of ATP hydrolysis. Traditionally, the accumulation of lactate and the consequent decline in pH within skeletal muscle during intense exercise are factors regarded as contributory to a reduction in the rate of ATPase activity. This phenomena can lead to the development of muscular fatigue. However, utilization of high-intensity training techniques appears to be effective in attenuating the decline in enzymatic function seen with decreases of intracellular pH.Thirty adult female Sprague-Dawley rats, approximately 50 days old, were randomly placed in either a sprint-training (n = 10), endurance-training (n = 10) or sedentary control group (n = 10). Each training condition was 10 weeks in duration. At the completion of training, the rats were sacrificed and the gastrocnemius and soleus muscles were removed. Muscle fibers were isolated from each muscle and stripped of their sarcolemma and sarcoplasmic reticulum using 1% triton X-100. The skinned muscle fibers were analyzed for ATPase activity at pH levels of 6.5, 7.0, and 7.5 using a fluorescence technique. Analysis of variance tests were performed on the data to evaluate differences in ATPase activity for each training condition at each pH as unique observations. Duncan's multiple range post hoc tests were used to identify any statistical differences.The ATPase activity of the sprint-trained rat gastrocnemius muscle increased significantly as pH declined (p < .05). Adenosine triphosphatase activity was also significantly greater (p < .05) at a pH of 6.5 for the sprint-trained animals than for any pH level in the endurance-trained and control rats. The soleus muscle of the sprint-trained rats showed similar results with its greatest ATPase activity at a pH of 6.5 (p < .05). Additionally, the ATPase at pH = 6.5 for the sprint-trained group was significantly higher (p < .05) than the ATPase activity of the endurance-trained and control group soleus muscle at a pH of 7.5. These data support the hypothesis that enzymatic activity can be modified to adapt to the disturbances in internal environment dictated by specific training patterns. They also present one mechanism that may account for the ability of the sprint athlete to maintain power outputs at hydrogen ion concentrations which would be exhaustive to endurance-trained or sedentary individuals.</p>