Lactate kinetics after concentric and eccentric isokinetic contractions in men

The purpose of this study was to investigate the lactate kinetics after concentric and eccentric isokinetic contractions. For this reason، ten recreational male participants performed two knee CON/CON and ECC/ECC isokinetic protocols (4 set، 10 repetitions، 60˚/s) in 2 separate sessions. Blood lactate concentrations measured before and at 0، 3، 6، 10، 15، 30، 45 and 60 minutes post-exercise. The individual blood lactate recovery curves were fitted to a biexponential time function. Paired t-test was used to compare the lactate responses to two exercise trials and the repeated measures of ANOVA was employed to compare the work rates following the sets in both sessions. Lactate concentration increased in response to concentric contraction from 1. 65±0. 34 to 5. 05±1. 19 (mmol. l) and in response to eccentric from 1. 71±0. 42 to 4. 12±1. 64 (mmol. l). Statistical analysis of data showed that increases in lactate concentrations were significantly higher in response to CON/CON protocol than ECC/ECC (P<0. 05). The lactate exchange (P<0. 01) and removal (P<0. 01) abilities were significantly higher after ECC/ECC exercise than CON/CON. Likewise، tpeak (P<0. 001) and t1/2 (P<0. 001) were significantly longer after CON/CON protocol than ECC/ECC. According to the findings of the present study، it could be concluded that concentric exercise leads to more metabolic stress than eccentric exercise. Therefore، based on the differences in the lactic acid production following these type of contractions، it is recommended that the type of recovery used following these contractions must be different and that following the concentric exercise the active recovery must be used.