Blood lactate responses to leg presses performed against inertial resistance.

Introduction: A flywheel ergometer has been devised which employs gravity-independent inertial resistance. Concentric and eccentric actions, which are integral to weight-bearing and ambulation activities, may be done on this ergometer. However, blood lactate responses to exercise on the ergometer by contractile mode and training volume are unknown.

Methods: Workout order was balanced so that subjects performed each type of ergometer leg press workout twice in a nonsequential manner. Per workout, 10 repetitions were performed per set. Workouts were as follows: three sets with concentric and eccentric (CE3) actions, three sets with concentric-only (CO3) actions, and six sets with concentric-only (CO6) actions. Pre- and 5-min post-exercise lactate was measured from a fingertip blood drop. Lactate means were compared with a 2 x 3 (time X workout) ANOVA with repeated measures applied to both independent variables and Scheffe's post hoc test. With body mass and performance measures as predictor variables, multivariate regression attempted to explain post-exercise and delta (post-pre) lactate variance.

Results: Post-exercise blood lactate values (mmol x L(-1), mean +/- SEM) were as follows: CE3, 8.08 +/- 0.44; CO3, 7.57 +/- 0.49; and CO6, 6.96 +/- 0.43. CE3 and CO6 workouts produced comparable volumes of work. Though several CE3 performance measures were significantly correlated to post-exercise and delta lactate values, power indices had the strongest relationship.

Discussion: Factors related to lactate production and clearance caused CE3 values to be highest. Power indices were most correlated to lactate as they denote a higher work rate and reliance on glycolysis.