Date Presented

Spring 4-5-2023

Document Type




First Advisor

Dr. Wendy Williamson, PT, DPT

Second Advisor

Dr. Price Blair, PhD

Third Advisor

Dr. John Styrsky, PhD


The aim of this study is to examine the differences in heart rate and lactic thresholdbetween female distance athletes and sedentary females. Lactate threshold is one of the variables used to measure anaerobic threshold. Anaerobic threshold characterizes the point when metabolic acidosis, along with the associated changes in gas exchange in the lungs, occurs during exercise. In this experiment, 16 female subjects -- 8 sedentary (174.56cm + 5.06 cm, 72.79 kg + 11.61kg), and 8 distance athletes (169.24cm + 8.58 cm, 57.44 kg + 5.37kg) -- were asked to ride a stationary bike for 18 minutes at 60 rotations per minute (rpm). The workload, measured in watts, began at 50 and increased by 50 watts every 3 minutes up to 300 watts, or 18 minutes. Each 3 minute segment comprised one “stage” of the test. Blood was collected for lactic acid measurements before the subject got on the bike, during stages 2, 3, 4, and 6, and 15 minutes after the conclusion of the bike test. Heart rate was continuously monitored using a heart rate strap and was recorded at the same time as the lactic acid measurements. Hemoglobin and hematocrit was also measured prior to and at the conclusion of the established bike protocol to examine the effects of dehydration. No heart rate deflection point was able to be discerned. There was a significant difference between both population’s lactic acid accumulation (p=0.012), but there was no difference in average heart rate (p = 0.509). There were no significant differences between the two population group’s hemoglobin and hematocrit (p = 0.520, p = 0.505). This topic is important to find a potential association between heart rate and lactic acidosis and its impact on performance in athletes. This will allow for specific training in athletes to help improve their aerobic threshold for training by decreasing their lactic acidosis.