Research article - (2020)19, 695 - 702
Beneficial Effects of Yoga Stretching on Salivary Stress Hormones and Parasympathetic Nerve Activity
Nobuhiko Eda1,2,, Hironaga Ito2,3, Takao Akama4
1Japan Institute of Sports Sciences, Tokyo, Japan
2Waseda Institute for Sport Sciences, Waseda University, Saitama, Japan
3Japan Sports Science Inc, Shizuoka, Japan
4Faculty of Sport Sciences, Waseda University, Saitama, Japan

Nobuhiko Eda
✉ PhD Japan Institute of Sport Sciences, 3-15-1 Nishigaoka, Kita-ku, Tokyo 115-0056, Japan
Email: nobuhiko.eda@jpnsport.go.jp
Received: 02-06-2020 -- Accepted: 20-09-2020
Published (online): 19-11-2020

ABSTRACT

This study aimed to determine the effect of yoga stretching on salivary stress hormones and cardiac autonomic nervous system. To our knowledge, this study is the first to investigate changes in cardiac autonomic nervous system after yoga stretching. In this crossover design study, 10 adult men (age, 26.3 ± 2.5 years) without yoga experience participated in the rest and yoga trials for 90 min. Measurements were carried out before (pre), immediately (post), 60 min, and 120 min after rest or yoga stretching. Saliva samples were collected by chewing a sterile cotton ball at a frequency of 60 cycles per minute. Salivary cortisol and testosterone concentrations were measured using an enzyme-linked immunosorbent assay. With the subjects in the sitting position, heart rate variability was measured using pulse analyzer plus for 150 seconds. As regards rate changes, salivary testosterone level tended to increase (p = 0.088), testosterone/cortisol ratio significantly increased (p < 0.05), and cortisol level significantly decreased (p < 0.05) at 120 min after yoga stretching. The square root of the mean-squared differences of successive normal-to-normal intervals and natural logarithm high-frequency component, which are indicators of parasympathetic nerve activity, increased at 60 min (p < 0.05) and 120 min (p < 0.05) in the yoga trial, respectively. In conclusion, yoga stretching can enhance parasympathetic nerve activity and improve stress hormones. Therefore, yoga stretching may be useful to compensate for physical inactivity and increase life expectancy in the general population.

Key words: Relaxation, mental state, autonomic nervous system, recovery, testosterone, cortisol

Key Points
  • We confirmed that salivary cortisol concentration decreased and testosterone/cortisol ratio increased after yoga stretching.
  • As major finding of this study, yoga stretching for 90 min is associated with a significant enhancement in the parasympathetic nerve activity.
  • Yoga stretching, which is a low-intensity exercise aimed at relaxation, may be useful for recovery after high-intensity training and athlete’s conditioning.








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