Lactate production in response to maximal and submaximal StairMaster PT4000 and treadmill exercise
Background. The purpose of this study was to measure the amount of lactate produced, as an indication of fatigue, in response to maximal and submaximal stairstepper (SM) and treadmill (TM) exercise. Methods. Thirty volunteers (15 males, mean age 23 yrs; 15 females, mean age 22 yrs) completed maximal and submaximal SM and TM protocols on four separate visits to the laboratory to determine maximal oxygen consumption ((V) over dotO(2)max), and blood lactate concentrations, Maximal TM testing consisted of the Bruce protocol, while the maximal SM protocol involved progressing in increments of 2 levels every 2 minutes. Eight minutes of submaximal TM and SM exercise was performed at an intensity of 65% of (V) over dotO(2)max, as measured during maximal TM and SM testing. Fifty microliters of blood was collected via fingerprick of the index finger prior to, and immediately post maximal and submaximal TM and SR I exercise, and during minutes 3, 5, and 7 of active recovery. Red blood cells were lysed and analyzed immediately using the YSI #1500 Sport lactate analyzer. Results. TM-VO2max, was significantly higher for both, males and females, compared to SM-(V) over dotO(2)max. Repeated measured analyses of variance revealed significantly higher blood lactate levels during the same relative submaximal workloads for SM compared to TM exercise. Conclusions. These findings suggest that an increased lactate production during submaximal SM exercise may result in early fatigue and, thereby, limit maximal performance on the SM.