Relative functional buffering capacity in 400-meter runners, long-distance runners and untrained individuals

Abstract

Buffering is a factor which influences performance in short and middle-term endurance by compensating exercise acidosis. The aim of the study was to establish whether respiration parameters are a relative measure of buffering capacity and to study the influence of buffering on specific performance parameters. Three groups (each of ten subjects) with defined degrees of adaptation [untrained (UT), aerobic-trained (AeT) and elite 400-m runners (AnT) with a best time of 48.47 ± 0.98 s] were examined in an incremental multi-stage test on the treadmill. Breath-by-breath gas analysis was performed using mass spectrometry and computer routines. Serum lactate concentrations were determined at each exercise level until subjective exhaustion. A value for the relative functional buffering capacity (re1FB) was calculated using exercise metabolic parameters. Running speed at the lactate threshold was used as the starting point of buffering. The start of respiratory compensation of acidosis (RCP) was taken as the endpoint of buffering. RCP was determined at the point of decrease in end-tidal CO₂ content (CO₂-ET). Re1FB was given in percent of buffering to running speed at RCP. Group AnT attained the same maximum performance data (maximum running speed, maximum rate of O₂ consumption) as group AeT. However, these values were attained in group AnT with a significantly higher re1FB (AnT: 31.0±3.2% vs. AeT: 15.7±3.9%,P < 0.0001), while a higher lactate threshold indicated a greater oxidative capacity in AeT (AeT: 3.07±0.26 m · s⁻¹ vs. AnT: 2.68±0.22 m · s⁻¹). It is concluded that the combination of ventilatory parameters and determining the LT seems to be a useful measure for the total amount of buffering during high-intensity exercise. The higher content of buffer-active proteins in sprinters' muscles may be considered the main cause of their higher re1FB.