Maximal Oxygen Consumption and Blood Lactate Levels as Measures of Exercise Intensity in Aging Rats

Abstract

To help quantify and determine appropriate exercise intensities for endurance training of aging animals, we compared measures of oxygen consumption (VO2) and blood lactate accumulation after 6 months of exercise training in aging rats. Blood lactate measures (using a portable lactate analyzer) were compared to VO2 measures in order to validate blood lactate as an appropriate and cost effective method of determining exercise intensity in aging animals. 122 adult (24 month) male Fischer 344 X Brown Norway (FBN) rats were divided into 3 groups based on exercise training intensity; high (H), moderate (M), and sedentary (S). M and H intensity animals trained at 13 m/min for 30 min/day, with the H group at 5% incline and the M group at 0%. VO2 and blood lactate responses to a maximal exercise test were measured at age 24 months and then after 6 months of exercise training. When compared to values at 24 months, VO2 max increased by 29.5%, 23.5%, and decreased by 1.2%, in the H, M, and S group respectively. Similarly lactate threshold increased by 53% in the H group, 34% in the M group, and decreased by 19% in the S group. Thus, with 6 months of endurance training, both VO2max and lactate threshold increased in a training intensity-dependent manner. This suggest that measures of blood lactate may provide an alternative means of assessing exercise intensity and the effects of exercise training in aging animals. Supported by: NIH AG030423