The Effects of Oral Administration of Peppermint Oil on improving DOMS Symptoms after an Eccentric Exercise Protocol

The aim of this study was to investigate the effects of consuming peppermint to improve symptoms of DOMS. For this purpose, 20 healthy male volunteer students of Mohaghegh Ardabili University (age: 21.37±1.7 years) were randomly divided into experimental (n=10) and control (n=10) groups. The experimental group daily consumed 50 microliter of peppermint oil in 500 ml of mineral water for 10 days and the control group received similar amount of mineral water (placebo). 7 days after consumption, the exercise protocol was conducted with leg press and a weight equal to 80% of maximal isotonic force in 4 sessions till exhaustion. Before 1, 24, 48 and 72 hours after exercise protocol, the variables were measured. For intra-group comparison, ANOVA test with repeated measures was used and for comparison of inter-group differences, independent t test was applied with significance level (P˂0.05). Cohen's d test was used to estimate the size of effect. Results showed that 10 days of peppermint consumption did not prevent DOMS symptoms. But a significant decrease in the concentration of CPK and LDH, (P=0.001) enzymes, cortisol hormone (P=0.01) and pain and inflammation (P=0.001) of peppermint group compared with the control group. Maximal isotonic force in the excremental group significantly decreased compared with the control group (P=0.001). The knee joint range of motion in the experimental group showed less inflammation than the control group (P=0.05). Overall, the results showed that 10 days of peppermint oil consumption cannot prevent chemical, functional and physical symptoms of DOMS. But it can have beneficial effects in a period of recovery.