A study showed clenching the right hand may help to form stronger memories of events or actions.
Curling up the left appears to aid later recollection of the memories.
Scientists asked volunteers to first memorise and later recall words from a 72-word list. Different groups were asked to perform right or left fist clenches at different times.
Participants were told to squeeze a rubber ball as hard as they could in their hands for 45 seconds while looking straight ahead.
The group that clenched their right fist when memorising and the left when recollecting did better than any of the others. They also performed better than participants who did not clench their fists at all, but merely cupped the ball
"The findings suggest that some simple body movements - by temporarily changing the way the brain functions - can improve memory," said psychologist Dr Ruth Propper, from Montclair State University, US, who led the study.
"Future research will examine whether hand clenching can also improve other forms of cognition, for example verbal and spatial abilities."
The findings are published in the online journal Public Library of Science ONE.
Previous studies had suggested that clenching a fist activates specific brain regions associated with memory formation.
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