Relationship between decrement of muscular pH and CO2 excess during incremental exercise.
- VernacularTitle:漸増運動による筋内ｐＨの低下と過剰ＣＯ２排出量との関係
- Author:
MITSUHARU INAKI
;
SHIN-YA KUNO
;
IZUMI ANNO
;
YUJI ITAI
;
SHIGERU KATSUTA
- Publication Type:Journal Article
- Keywords:
31P NMR;
intracellular pH;
CO2 excess;
bicarbonate buffering system
- From:Japanese Journal of Physical Fitness and Sports Medicine
1993;42(1):53-58
- CountryJapan
- Language:Japanese
-
Abstract:
A study was conducted to investigate using 31P NMR the relationship between the total excess volume of CO2 output (CO2 excess) due to bicarbonate buffering of lactic acid produced in exercise and the decrease of intracellular pH during incremental exercise. Five sprinters and 5 joggers performed incremental exercise to exhaustion on an bicycle ergometer. The values of CO2 excess and CO2 excess per body weight (CO2 excess/W) were not different between the sprinters (2388±659ml, 36.7±8.5 ml·kg-1) and the joggers (2275±278ml, 40.0±6, 3ml·kg-1) . Below the ventilatory threshold (VT), from VT to the respiratory compensation point (RCP), and above RCP, the Vod2-Vco2 slopes were not different between the sprinters and the joggers, respectively (0.95±0.05 vs 0.95±0.06, 1.21±0.11 vs 1.30±0.14, 1.69±0.24 vs 1.76±0.18) . However, the joggers showed significantly higher CO2 excess/W per blood lactate accumulation (ΔLa) in exercise (CO2 excess/W/ΔLa, 5.34±0.32ml·kg-1·mmol-1·l-1) than the sprinters (4.50±0.14ml·kg-1·mmol-1·l-1) . The decrement of intracellular pH during incremental exercise showed a tendency to be smaller in joggers (0.63±0.18 pH unit) than in sprinters (0.83±0.10 pH unit), although there was no significant difference between the two groups. The values of CO2 excess/W/ΔLa were correlated with the decrease of intracellular pH (r=-0.792, p<0.01) . It is suggested that CO2 excess/W/ΔLa reflects the efficiency of the bicarbonate buffering system, and could be an important factor influencing the decrease of intracellular pH due to lactate production.
