RELATIVE FUNCTIONAL BUFFERING CAPACITY IN 400-METER RUNNERS, LONG-DISTANCE RUNNERS AND UNTRAINED INDIVIDUALS

Buffering is a factor which influences performance in short and middle -term endurance by compensating exercise acidosis. The aim of the stud y was to establish whether respiration parameters are a relative measu re of buffering capacity and to study the influence of buffering on sp ecific performance parameters. Three groups (each of ten subjects) wit h 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] w ere examined in an incremental multi-stage test on the treadmill. Brea th-by-breath gas analysis was performed using mass spectrometry and co mputer routines. Serum lactate concentrations were determined at each exercise level until subjective exhaustion. A value for the relative f unctional buffering capacity (relFB) was calculated using exercise met abolic 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 det ermined at the point of decrease in end-tidal CO2 content (CO2-ET). Re lFB was given in percent of buffering to running speed at RCP. Group A nT attained the same maximum performance data (maximum running speed, maximum rate of O-2 consumption) as group AeT. However, these values w ere attained in group AnT with a significantly higher relFB (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 tha t the combination of ventilatory parameters and determining the LT see ms to be a useful measure for the total amount of buffering during hig h-intensity exercise. The higher content of buffer-active proteins in sprinters' muscles may be considered the main cause of their higher re lFB