A Functional Study of Oxidative Muscle Efficiency in Older People

Abtract To assess, in vivo, muscle oxidative efficiency in older people we studied haematic lactate in blood samples obtained from 34 older and 10 young subjects before and after an incremental exercise performed on a treadmill, in order to identify a possible defect as a factor determining motor performance impairment. The exercise protocol consisted of 11 steps of 2 minutes of duration, at a constant speed of 3 km/h; the grade was 0 at the beginning and was incremented of 2.5% each step. Lactate was evaluated at rest and during recovery (at 1’, 5’, 10’ and 30’ after the end of the exercise). We found that lactate resting values didn’t show a significant difference between older and young people. During recovery, older people showed significantly higher values at any time. The analysis of results permitted to distinguish a subgroup of 11 out of 34 subjects with a behaviour similar to young’s one. In conclusion the abnormal lactate increase observed in this study points out a reduced oxidative muscle function in older people. Interestingly, the test employed allowed to identify two subgroups: with normal levels and with altered levels of lactate. The latter could due to a different individual mt-DNA damage susceptibility.