Leg day is usually about the stairs, the hike or the squat you want to finish strong. Two trials that put people on strength training and measured their thinking afterwards found something else worth knowing.
A randomised trial is the stronger kind of test, because people are assigned to training or to a comparison by chance, so the groups start out alike. In Vancouver, 155 women aged 65 to 75 were assigned to strength training once a week, strength training twice a week, or balance and toning classes twice a week, for a year.1
The main measure was the Stroop test, where you name the colour of the ink a word is printed in while the word itself spells a different colour. It measures focus and the ability to ignore a distraction. Scores improved by 12.6% with once-a-week training and 10.9% with twice a week, and fell by 0.5% in the comparison group. The women whose focus improved most also walked faster by the end of the year.1
One result went the other way: both strength groups lost more whole-brain volume over the year than the comparison group. The authors report it without explaining it, and it is a reason to read the focus result as one measure improving, not the brain as a whole.1
In the second trial, 100 adults aged 55 and over with mild cognitive impairment, a measurable dip in memory or thinking, did high-intensity strength training or a sham exercise programme two to three days a week for six months.2 Neither the participants nor the people testing them knew who was in which group.
Strength training improved their scores on a standard thinking test, and the people who got stronger improved most. When the researchers worked out what carried the effect, it was the gain in lower-body strength that statistically explained the improvement in the overall score, while the gain in aerobic fitness did not.2
These were people who already had some difficulty with memory or thinking, so the result applies to people in that position. It is the clearest sign in these trials that the strength itself, and the legs in particular, had something to do with the change.
A review that pooled 36 randomised trials in adults over 50 found that exercise gave a modest improvement in thinking scores, and that aerobic exercise, strength training, mixed programmes and tai chi each showed a benefit on their own.3 Across all types, sessions of 45 to 60 minutes at moderate intensity or more were linked to benefit, and the result held whether or not the participants had a diagnosed problem with thinking.
The authors rated the evidence as moderate quality, and noted the limit every exercise trial shares: people cannot be kept from knowing which group they are in.
The Vancouver trial measured one year and the second trial six months, so neither can say what strength training does to memory over decades. Each used a few specific tests, so a gain in focus or in a thinking scale is not the same as a sharper mind in every sense. And the second trial was in people who already had mild cognitive impairment, so its result belongs to them first.
What the trials do show, together, is that strength training can improve some measures of thinking in the groups they tested, and that in one of them the strength gain was what carried it. That is a good reason to train, on top of the ones you already had.
Whatever the brain turns out to get from it, stronger legs carry you through the day. At the gym, squats, Bulgarian split squats, Romanian deadlifts and hip thrusts all work the legs, and two or three of them make a good session. Going a little heavier each time, 2 kg next week and 5 kg the week after, lets you see how far you can go. At home, taking the stairs over the lift, step-ups on a sturdy chair and lunges do the job.
Food is the other half. A review of 49 randomised trials with 1,863 people found that adding protein to strength training gave an extra 2.49 kg on the heaviest weight people could lift once, and an extra 0.30 kg of fat-free mass, which is everything in the body except fat, so you keep your muscle and add to it.4
Carbs matter too. Your muscles store carbohydrate as glycogen, their fuel for hard work, and long, hard sessions draw it down. The International Society of Sports Nutrition notes that carbohydrate with protein around training may support strength and body composition, and that good-quality protein in the two hours after a session strongly switches on muscle rebuilding.5 So easy carbs before you train, a banana or toast with jam, and a high-protein meal with carbs on the plate afterwards cover both: protein to build the muscle and carbs to refuel it.
Two randomised trials found strength training improved thinking scores, and in one the gain in leg strength explained the gain in thinking, so strength training and the brain belong in the same sentence, with the limits above. Whatever the brain gets from it, stronger legs carry you through the day. Eighty Thirty works out your daily protein and keeps count for you, so your training has what it needs to rebuild, day after day. Start with our free macro calculator.
In the trials run so far, yes on some measures. A year of once- or twice-weekly strength training improved a test of focus by 12.6% and 10.9% in 155 women, and a six-month trial in 100 adults with mild cognitive impairment improved thinking scores.12
For the focus test in the Vancouver trial, once a week did about as well as twice: 12.6% against 10.9%, while the comparison group slipped by 0.5%. Twice a week still builds more strength, and the review found sessions of 45 to 60 minutes were linked to benefit.13
In the six-month trial, it was the gain in lower-body strength that statistically explained the improvement in thinking scores, while the gain in aerobic fitness did not. The researchers call for more work on why, so the mechanism is still open.2
The review of 36 trials found aerobic exercise, strength training, mixed programmes and tai chi each showed a benefit on thinking scores, so neither comes out on top. Its authors suggest both aerobic and strength exercise at moderate intensity on as many days as you can manage.3
Enough that your training has something to build with. Across 49 trials, adding protein to strength training gave an extra 2.49 kg on the heaviest lift and 0.30 kg of fat-free mass. Eighty Thirty's free macro calculator works out how much protein you need from your weight.4
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