Abstract
The purposes of this study were (a) to investigate blood lactate accumulation (BLA) during a standardized isokinetic test and (b) to compare the BLAs of middle-distance runners and “sedentaries.” Seventeen subjects (mean age of 28.6 ± 5.5 yr), including seven middle-distance runners (national level) and ten sedentaries practicing recreational sports were evaluated. Testing involved unilateral use of the flexor and extensor muscles of the thigh. Exercise involved 5-second isometric tests at 0, 30, and 60 degrees, isokinetic tests at 60 and 180 deg/sec, and a 30-movement endurance test at 180 deg/sec beginning with the dominant extremity. Blood samples were taken at rest, after each exercise set, 6 minutes after the completion of the initial extremity test, and 3 minutes after definitive stop for lactate analysis. Mean BLA of all subjects increased during both isometric and isokinetic exercises. However, there was no significant increase after isometric exercises. BLA reached 4.8 ± 1.42 mmol/L after the end of the first isokinetic endurance test (significant at p < 0.001) to the seated rest value. Mean BLA values obtained for the second extremity are greater than those of the initial value at p < 0.001. At R3, BLA increased to 7.02 ± 2.62 mmol/L. The BLA values of “sedentaries” were higher than those of the middle-distance runners: 2.74 ± 0.67 versus 1.61 ± 0.84 mmol/L at 180 deg/sec or 8.22 ± 2.22 versus 5.3 ± 2.23 mmol/L (significant at p < 0.01) 3 minutes after definitive stop. This study demonstrates that short (6–10 sec) heavy isokinetic exercise and isokinetic endurance tests increase blood lactate concentration. These results indicate that metabolic conditions at the beginning of the second extremity test differ from those of the initial rest conditions.