(1) THE EFFECT OF MODERATE AEROBIC EXERCISE ON SALIVATORY CORTISOL

Purpose: Investigate the effects of a single short duration (< 30 min), moderate intensity (70% HRR) bout of running on salivatory cortisol levels. Methods: 20 DIII college tennis players (age 19.7 ± 1.5 years, height 175.1 ± 11.6 cm, weight 71.9± 11.1 kg) volunteered for this study. Salivatory cortisol was measured prior to exercise. Participants then ran for 25 minutes on a treadmill with 15 minutes being at 70% of target heart rate reserve. For the first 5 minutes, the treadmill was gradually increased until target heart rate was met. Following the 15 minutes of running, a 5-minute cool-down was performed at a slower speed. Thirty minutes following exercise, salivatory cortisol was measured again. A paired sample t-test was run to compare pre- and post-values. Results: Pre-exercise cortisol levels were 0.40±0.21 ml/dl. Post-Exercise levels were 0.27 ±0.16 ml/dl. P=0.006. Conclusions: Exercise has been shown to decrease stress. As suggested by the results of this study, a 25-minute workout consisting of 15 minutes of running may be enough to lower cortisol levels and could have an impact on how stress affects the body. This may have long term implications if incorporated into a daily routine by reducing the negative impact of cortisol on the body. Practical Applications: Less than 30 minutes of physical activity at moderate intensity can acutely lower cortisol levels. Acknowledgements: None