A centuries-old samurai etiquette practice may hold the key to stronger legs in just five minutes a day, with a new study finding that “Rei-ho” squats can boost knee strength by 26% and may help older adults stay independent.
Aging brings with it a natural decrease in muscle strength that older folks have to work to maintain. But, as you age, you just want to live your life. You don’t want to be paying for a gym membership or expensive equipment; you want exercises that are quick and free. That’s where a new study comes in.
Researchers from Tohoku University in Japan have found that five minutes a day of an exercise that formed part of the traditional practice of Rei-ho, or etiquette, once practised by samurai, is an effective way to maintain lower body strength.
“In particular, knee extension strength – the force used to straighten knees – is a key measure of mobility and daily functioning,” said Ayaka Ogasawara, the study’s lead author. “These exciting results suggest that Rei-ho may help seniors maintain their independence.”
The researchers recruited 34 healthy adults, aged over 20, with no prior experience in Rei-ho. Half were randomly assigned to a Rei-ho training group, and the other half were assigned to a control group. The Rei-ho group did a five-minute exercise routine (10 to 12 slow squats and 10 slow sit-to-stands) at least four days a week for three months. No special equipment was required. The control groups continued with their daily lives and did not do any extra exercise. The researchers measured participants’ knee extension strength before and after the three-month period, using a force-measuring chair device.
Ayaka Ogasawara et al. (2025)
The knee extension strength of those in the Rei-ho group increased by about 26% after three months, while the control group saw only a 2% to 3% improvement that was likely from natural variability and not the result of training. The average participant trained four to five days a week. A few participants reported minor issues such as knee or back pain, but these were not serious and most continued training.
The study does have limitations. Principally, the small sample size. Only 30 people completed the trial, 14 in the exercise group and 16 in the control group. Most practice was done at home, so researchers couldn’t always verify whether participants were using the perfect Rei-ho technique. More women than men participated in the study, but analysis suggested this didn’t skew the results. The study only measured knee extension strength at one angle (90°). It didn’t test walking speed, balance, or other functional abilities. The participants were healthy, relatively young to middle-aged adults. Results may not apply directly to frailer elderly adults or people with knee conditions.
Regardless of these limitations, the study suggests that a five-minute-a-day exercise that requires no equipment and could easily be incorporated into everyday life is beneficial. Since the movements are slow and use bodyweight only, they’re lower-risk than heavy resistance training. While this study tested younger adults, the method could help older adults maintain leg strength and reduce their risk of falling, which would foster independence. However, further trials in older populations are needed.
“We think it’s also valuable that those outside of Japan who want to try Rei-ho would also be able to experience a unique aspect of ancient Japanese tradition in addition to the health benefits,” said study co-author Akira Sato.
The study was published in The Tohoku Journal of Experimental Medicine.
Source: Tohoku University
