Relationships between oxygen Uptake kinetics on recovery from maximal exercise and blood lactate, glucose and alanine metabolism / 体力科学

ABSTRACT

A study was performed to clarify the relationships between oxygen uptake (VO<SUB>2</SUB>) kinetics on recovery from incremental maximal exercise and blood lactate, glucose and alanine metabolism. Eight healthy males aged 21.6±3.3 years were studied. The incremental exercise test was performed using a modified version of Bruce's protocol until 30 min after exhaustion. The VO<SUB>2</SUB> responses on recovery were fitted by a two-component exponential model. Blood lactate concentration in the recovery phase was fitted by a bi-exponential time function to assess the velocity constant of the slowly decreasing component (γ2) expressing the rate of blood lactate removal. Both blood lactate and plasma alanine concentration were significantly increased from rest to maximal exercise, and were significantly decreased thereafter, but remained above resting values for 30 min after the maximal stage. Blood glucose concentration was significantly decreased following maximal exercise and returned to the pre-exercise value by 30 min after the maximal stage. Concentrations of plasma branched-chain amino acids (valine, leucine and isoleucine) were significantly decreased from the maximal stage until 30 min after exhaustion. The time constant of the slow component on recovery VO<SUB>2</SUB> [τVO<SUB>2</SUB> (s) ] was correlated with neither γ2 nor the degree of change in blood lactate from the maximal stage until 30 min after exhaustion (&Delta;lactate) . However, τVO<SUB>2</SUB> (s) was significantly correlated with both &Delta; blood glucose and &Delta; alanine. In addition, &Delta; alanine was significantly correlated with &Delta; blood glucose. From these results, we conclude that oxygen uptake kinetics after exhaustive maximal exercise is related to glucose resynthesis through alanine metabolism, as compared with that from lactate metabolism.