Browse evidence-based analysis of health-related claims and assertions
Stretching right after exercise probably doesn’t help you become more flexible right away, at least in healthy adults. Even though people often stretch to improve flexibility, it might not do much if it’s too short or not intense enough.
Quantitative
Stretching after exercise probably doesn't help healthy adults perform better right after, and won't boost things like how high you can jump or how fast you can sprint.
Stretching after exercise probably doesn't help you regain muscle strength faster, and if it does, the benefit is so small it wouldn't really matter for most people who work out.
Stretching after exercise probably doesn't help much with muscle soreness the next day, even if you're healthy and active.
Doing certain types of hard arm exercises that lengthen the muscle while it's working can make your arms weaker and less flexible within a day.
Causal
When women do certain types of arm exercises that involve stretching the muscle while contracting it, they tend to feel more soreness and their muscles get thicker — probably because of inflammation and fluid buildup.
Mechanistic
Doing super-slow, lengthening muscle exercises (like lowering a heavy weight) causes more muscle damage than shortening ones, and you can see it on an ultrasound of your arm muscles.
Doing a new type of strength exercise that stretches your biceps a lot can cause temporary muscle damage and soreness in women, and these effects can last up to four days.
When male college athletes do heavy squats, their balance gets better over the next day, peaking at 24 hours — and it doesn’t matter how they spaced out their sets, just that time passed.
Correlational
Doing heavy squats the night before can help young male athletes change direction faster the next day, whether they take short breaks during sets or not.
Guys who lift weights might be quicker on their feet 6 hours after squatting if they take extra short breaks during their sets instead of doing them the usual way.
For male college athletes, taking extra short breaks within sets during heavy weightlifting might help them sprint faster 6 hours later compared to doing regular sets.
Young male athletes who take short breaks during heavy squats might jump a little higher six hours later compared to those who rest longer between sets — it could help their muscles stay sharp for explosive moves.
The Cronometer app tends to show higher amounts of fibre and vitamins A and D in the diets of Canadian endurance athletes than what's actually in the official Canadian food database — probably because it counts fibre differently and includes fortified foods from other countries.
MyFitnessPal isn't very accurate for tracking calories and nutrients in Canadian endurance athletes — it often gets protein wrong for men and overestimates calories and carbs for women, so it might not be good for serious diet planning.
Descriptive
Cronometer does a pretty good job tracking calories and key nutrients like carbs, fat, and protein for Canadian endurance athletes — its numbers are very close to the official nutrient database.
When people stop training, their muscles don't get weaker as fast as they shrink — strength sticks around more than size, maybe because the brain and nerves keep working well even as muscles get smaller.
MyFitnessPal isn’t very reliable when it comes to tracking sodium and sugar — different people log the same foods differently, especially men, so it might not be good for studies or health advice.
If you gain more muscle and strength when working out, you might also lose more when you stop — your gains and losses seem to go hand in hand.
Cronometer is a food-tracking app that gives very consistent results when different people log the same meals — especially for endurance athletes in Canada — so researchers and doctors can trust it for accurate diet tracking.
Almost everyone benefits from strength training — if someone doesn’t see gains in one area or one round of training, they likely will in another. Real 'non-responders' are super rare.
If you respond really well (or not so well) to a weight training program, you’ll probably have a similar result if you do the exact same program again after taking a break.
If you've never worked out before, lifting weights for 10 weeks can make your muscles stronger and bigger — especially in your legs and arms — while people who don’t train see almost no changes.
Walking a little more every day — like 500 extra steps — might help you live longer by reducing your chances of dying from heart problems.