Study: Moderate-to-vigorous exercise can boost memory for 24–48 hours following workout

What’s good for your heart is good for your brain. Just as phys­i­cal activ­i­ty helps keep our bod­ies fit and strong as we age, it also helps main­tain our cog­ni­tive func­tion – and is even linked with low­er demen­tia risk.

Yet beyond the longer term cog­ni­tive ben­e­fits of phys­i­cal activ­i­ty, exer­cise also seems to give a short-term boost to cog­ni­tive per­for­mance last­ing from min­utes to hours. Accord­ing to our lat­est study, this cog­ni­tive boost may last up to 24-hours after exer­cis­ing. Because some cog­ni­tive abil­i­ties start to decline as we get old­er, even small boosts to cog­ni­tive func­tion can help keep us active and inde­pen­dent for longer.

Stud­ies con­duct­ed both in the lab and real-world set­tings have shown that peo­ple who are more phys­i­cal­ly active – whether that’s in the form of struc­tured work­outs or they just do more activ­i­ty in their day-to-day lives – per­form bet­ter on cog­ni­tive tests in the hours after exercising.

But one ques­tion researchers are still try­ing to answer is how long these cog­ni­tive ben­e­fits last – par­tic­u­lar­ly in old­er adults, where main­tain­ing cog­ni­tive func­tion is very impor­tant. This is what our research aimed to do.

The New Study: How does physical activity impact next-day cognitive, memory performance?

In our study of mid­dle-aged and old­er adults, we found that peo­ple who did more mod­er­ate-to-vig­or­ous phys­i­cal activ­i­ty (such as jog­ging or cycling) per­formed bet­ter on mem­o­ry tests the fol­low­ing day. This sug­gests that the mem­o­ry ben­e­fits of phys­i­cal activ­i­ty might last longer than the cou­ple of hours found in pre­vi­ous, lab-based studies.

Our study involved 76 par­tic­i­pants aged 50–83. Each par­tic­i­pant wore a wrist-worn activ­i­ty track­er for eight days and nights. They were instruct­ed to go about their dai­ly lives as usu­al. From these activ­i­ty track­ers, we were able to see how much time par­tic­i­pants spent being seden­tary or phys­i­cal­ly active each day – and how intense this phys­i­cal activ­i­ty was.

Because phys­i­cal activ­i­ty also affects sleep qual­i­ty – par­tic­u­lar­ly the amount of time spent in the deep­est and most restora­tive sleep phase, referred to as slow-wave sleep – we were also inter­est­ed in explor­ing the role of sleep in cog­ni­tive per­for­mance. We extract­ed sleep qual­i­ty char­ac­ter­is­tics from the activ­i­ty track­ers – includ­ing total sleep dura­tion and time spent in slow-wave sleep.

On each day the par­tic­i­pants wore the activ­i­ty track­ers, they also took a set of cog­ni­tive tests. Some of these cog­ni­tive tests assessed episod­ic mem­o­ry (being able to rec­ol­lect pre­vi­ous expe­ri­ences) and work­ing mem­o­ry (the abil­i­ty to tem­porar­i­ly store infor­ma­tion in the mind). The type of cog­ni­tive tests the par­tic­i­pants were giv­en alter­nat­ed each day to reduce the chances of par­tic­i­pants learn­ing and remem­ber­ing the answers.

We want­ed to be sure we had iso­lat­ed the effect of phys­i­cal activ­i­ty and sleep on next-day cog­ni­tive per­for­mance. So, we took into account a num­ber of demo­graph­ic, socioe­co­nom­ic and lifestyle char­ac­ter­is­tics that could have dis­tort­ed the results. Each day, we also account­ed for a participant’s pre­vi­ous cog­ni­tive score to be sure we were focus­ing on day-to-day improve­ments in cog­ni­tive performance.

The Results: Better episodic and working memory scores were the following day

We found that the more time a par­tic­i­pant spent doing mod­er­ate-to-vig­or­ous phys­i­cal activ­i­ty, the bet­ter their episod­ic and work­ing mem­o­ry scores were the fol­low­ing day. Get­ting more sleep, par­tic­u­lar­ly slow-wave sleep, was also asso­ci­at­ed with improve­ment in mem­o­ry scores – inde­pen­dent­ly of phys­i­cal activ­i­ty. But peo­ple who were more seden­tary had worse work­ing mem­o­ry scores the fol­low­ing day.

While the improve­ment in mem­o­ry per­for­mance was rel­a­tive­ly mod­est, none of our par­tic­i­pants had cog­ni­tive impair­ment or demen­tia. So they real­is­ti­cal­ly did not have much room to improve on these tests to begin with.

But these results could serve as a jump­ing-off point for future stud­ies exam­in­ing next-day cog­ni­tive per­for­mance in peo­ple with neu­rode­gen­er­a­tive dis­eases – such as demen­tia, where we might see larg­er improve­ments in test scores. These find­ings also need repli­cat­ing in a larg­er study before we can be sure of them.

The short-term cog­ni­tive ben­e­fits of exer­cise are thought to occur because exer­cise stim­u­lates blood flow and the release of spe­cif­ic brain chem­i­cals that con­tribute to cog­ni­tive func­tion. Gen­er­al­ly, these neu­ro­chem­i­cal ben­e­fits are thought to last a cou­ple hours fol­low­ing exer­cise. How­ev­er, oth­er changes induced by exer­cise — includ­ing some impli­cat­ed in mem­o­ry func­tion — might last for 24–48 hours fol­low­ing exer­cise. This might under­lie the results we found in our study.

Our find­ings point to the impor­tance of main­tain­ing active lifestyles as we age – and sup­port­ing this active lifestyle with good sleep.

– Mikaela Bloomberg is a Senior Research Fel­low in Social Epi­demi­ol­o­gy and Social Sta­tis­tics in the Depart­ment of Epi­demi­ol­o­gy and Pub­lic Health at UCL. This arti­cle was orig­i­nal­ly pub­lished on The Con­ver­sa­tion.

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SHARPBRAINS is an independent think-tank and consulting firm providing services at the frontier of applied neuroscience, health, leadership and innovation.
SHARPBRAINS es un think-tank y consultoría independiente proporcionando servicios para la neurociencia aplicada, salud, liderazgo e innovación.

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