The effects of interval training and age on blood lactate (La) levels and lactate dehydrogenase (LDH) activity in male Wistar rats

Introduction: Physical activity and age are among the factors affecting lactate levels and lactate dehydrogenase activity. Physical activity appears to be able to counterbalance the morphological and metabolic changes associated with aging that decrease physical ability and performance. Objectives: The purpose of the present study was to assess the effects of interval training on blood lactate levels and lactate dehydrogenase activity in young and old rats. Materials and Methods: A total of 40 male rats were selected and then divided into two age groups -the old group (20 rats aged 27 months and weighing 389±31 g) and the young group (20 rats aged 3 months and weighing 224±13 g). Each group was itself randomly divided into an experimental group (n=10) and a control group (n=10). The training protocol involved 4 minutes of running on the treadmill with intervals of 2 minutes active resting in 10 training bouts of 60 minutes, for 6 sessions per week and for 8 weeks and gradually increasing in intensity. Twenty-four hours after the last training session, the rats were anesthetized with a mixture of ketamine and xylazine in order for their blood sample to be collected from their cardiac puncture. Their lactate levels and LDH activity were then measured by an enzymatic method. Data were analyzed using the one-way ANOVA and Tukey's post-hoc test. Results: The results showed no significant differences in blood lactate levels between the four groups; however, LDH activity was significantly higher in the young experimental group than in the young control group (p<0/05). Conclusion: The results indicate that lactate is increasingly cleared by interval training. It also appears that the effect of training on lactate clearance is similar in both young age and old age. Monitoring blood lactate levels benefits muscle glycogen replenishment and intracellular pH (pHi) regulation.