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Na een uurtje yoga zijn de zijn de (stress) hormonen cortisol
een stuk lager, ieder keer op nieuw.
Many people turn to yoga to
relieve stress, and new study findings suggest they're doing the right thing.
U.S. researchers discovered
that after a single session of yoga, levels of the stress hormone cortisol
dropped, even in people who were trying yoga for the first time.
During the study, Dr. George
Brainard of the Center of Integrative Medicine of Thomas Jefferson University in
Philadelphia and colleagues measured levels of cortisol in the blood of 16
healthy yoga novices before and after a 50-minute period of rest.
The researchers then measured
cortisol levels before and after a 50-minute yoga session. Participants then
practiced yoga for another five days, and had their cortisol levels tested
before and after the seventh yoga session.
Brainard and his team found
that cortisol levels decreased more after a session of yoga than after the rest
period, even on the first day of practice.
"We observed a decrease
(in cortisol) after the first time they were introduced to yoga, and after the
seventh time as well," study co-author Justin Mager told.
Just how that drop in cortisol
might benefit yoga practitioners, however, is less clear, Mager and Brainard
said in an interview on Wednesday.
For instance, Brainard said
that he and his colleagues measured cortisol levels immediately after a yoga
session, and there is no way to know how long that hormonal change will last.
Brainard explained that
cortisol levels normally fluctuate. However, in the presence of stress, cortisol
levels can spike, and tend to rapidly drop once the stress disappears, he said.
But when people say they feel
stressed, much more is going on in their body besides an increase in cortisol,
Brainard said. So it is unclear what effect a change in levels of one stress
hormone will have on the body, he noted.
This study "opens the
door" to these questions, Brainard said, and further research will have to
determine whether the decrease in cortisol after yoga is sustained, and whether
that hormonal change has a positive effect on health.
"My suspicion is that the
answer to all that may well be yes," he said.
The research was presented in Philadelphia at the 85th Annual Meeting of The Endocrine Society. (2003)