Comparison of muscle buffer capacity and repeated-sprint ability of untrained, endurance-trained and team-sport athletes

We measured the muscle buffer capacity (βm) and repeated-sprint ability (RSA) of young females, who were either team-sport athletes (n=7), endurance trained (n=6) or untrained but physically active (n=8). All subjects performed a graded exercise test to determine \( {\text{\ifmmode\expandafter\dot\else\expandafter\.\fi{V}O}}_{{{\text{2peak}}}} \) followed 2 days later by a cycle test of RSA (5×6 s, every 30 s). Resting muscle samples (Vastus lateralis) were taken to determine βm. The team-sport group had a significantly higher βm than either the endurance-trained or the untrained groups (181±27 vs. 148±11 vs. 122±32 μmol H⁺ g dm⁻¹ pH⁻¹ respectively; P<0.05). The team-sport group also completed significantly more relative total work (299±27 vs. 263±31 vs. 223±21 J kg⁻¹, respectively; P<0.05) and absolute total work (18.2±1.6 vs. 14.6±2.4 vs. 13.0±1.9 kJ, respectively; P<0.05) than the endurance-trained or untrained groups during the RSA test. The team-sport group also had a greater post-exercise blood lactate concentration, but not blood pH. There was a significant correlation between βm and RSA (r = 0.67; P<0.05). Our findings show that young females competing in team sports have a larger βm than either endurance-trained or untrained females. This may be the result of the intermittent, high-intensity activity during training and the match play of team-sport athletes. The team-sport athletes also had a greater RSA than either the endurance-trained or untrained subjects. The greater total work by team-sport athletes was predominantly due to a better performance during the early sprints of the repeated-sprint bout.