Dependence of the maximal lactate steady state on the motor pattern of exercise

Background-Blood lactate concentration (BLC) can be used to monitor relativ e exercise intensity. The highest BLC representing an equilibrium between l actate production and elimination is termed maximal lactate steady state (( MLSS). MLSS is used to discriminate qualitatively between continuous exerci se, which is limited by stored energy, from other types of exercise termina ted because of disturbance of cellular homoeostasis. Aim-To investigate the hypothesis that MLSS intraindividually depends on th e mode of exercise. Methods-Six junior male rowers (16.5 (1.4) years, 181.7 (3.1) cm, 69.8 (3.3 ) kg) performed incremental and constant load tests on rowing and cycle erg ometers. Measurements included BLC, sampled from the hyperaemic ear flap, h eart rate, and oxygen uptake. MLSS was defined as the highest BLC that incr eased by no more than 1.0 mmol/l during the final 20 minutes of constant wo rkload. Results-In all subjects, MLSS was lower (p less than or equal to0.05) durin g rowing (2.7 (0.6) mmol/l) than during cycling (4.5 (1.0) mmol/l). No diff erences between rowing and cycling were found with respect to MLSS heart ra te (169.2 (9.3) v 172.3 (6.7) beats/min), MLSS workload (178.7 (29.8) v 205 .0 (20.7) W), MLSS intensity expressed as a percentage (63.3 (6.6)% v 68.6 (3.8)%) of peak workload (280.8 (15.9) v 299.2 (28.4) W) or percentage (76. 4 (3.4)% v 75.1 (3.0)%) of peak oxygen uptake (60.4 (3.4) v 57.2 (8.6) ml/k g/min). Conclusions-in rowing and cycling, the MLSS but not MLSS workload and MLSS intensity intraindividually depends on the intensity intraindividually depe nds on me motor pattern of exercise. MLSS seems to decrease with increasing mass of the primarily engaged muscle. This indicates that task specific le vels of MLSS occur at distinct levels of power output per unit of primarily engaged muscle mass.