Browse evidence-based analysis of health-related claims and assertions
Doing gentle strength exercises slowly and steadily twice a week for 12 weeks makes older adults' knee muscles stronger.
Causal
Doing gentle strength exercises slowly and steadily twice a week for 12 weeks makes older adults' leg muscles stronger.
Gentle weight training done slowly and steadily twice a week for 12 weeks can make older adults' thigh muscles thicker and stronger.
Lifting heavier weights (60-80% of your max) makes you stronger than lifting lighter weights, even if you do the same total amount of work, especially after 12 weeks of training.
Lifting weights at different effort levels all help men get stronger and build bigger muscles after 12 weeks, but using the lightest effort isn't as good as pushing harder.
Lifting heavier weights (80% of your max) builds bigger muscles faster than lifting lighter weights (20% of your max) when you do the same total work, with thigh muscles growing about 20% more and arm muscles growing about 25% more after 12 weeks.
When people do LST training instead of HN training, their blood pressure doesn't go as high during exercise, which might make it safer for those who could have heart problems.
A tough workout called HN helps young men lose belly fat after 13 weeks, while an easier workout called LST doesn't really help with fat loss. The tough workout works better because it makes your body work harder and releases special chemicals.
A lighter workout style called LST can make your muscles produce as much lactic acid as a harder workout called HN, which might help build muscle size just as well, even though it's less intense.
Mechanistic
A certain type of weight training keeps your muscles working non-stop, making them use more oxygen and possibly grow bigger because of changes inside your body.
Doing slow, low-intensity weight training twice a week for about three months can build muscle and strength almost as well as fast, heavy lifting in young men who don't normally exercise.
When people lift weights in a way where they can do 12 reps max, getting stronger is closely tied to getting bigger muscles. But this link isn't seen when lifting for only 4 or 8 reps max.
Correlational
When men lift weights, doing more reps with lighter weights (like 12 reps max) gives less strength improvement than doing fewer reps with heavier weights (like 4 or 8 reps max), even if the total workout effort is the same.
If you do the same total amount of weightlifting work, lifting heavier weights fewer times or lighter weights more times gives men about the same muscle growth.
Whether you lift lighter weights or heavier weights until you can't do any more reps, both ways give you the same muscle growth and strength gains if you're already used to training.
Lifting heavier weights makes you stronger and improves your brain-muscle connection more than lifting lighter weights, even if you do the same total amount of work and build the same muscle size.
When lifting lighter weights, pushing until you can't do any more reps helps build more muscle than stopping early. But with heavier weights, pushing to failure doesn't give much extra muscle growth compared to stopping a bit sooner.
Quantitative
Doing slow, gentle weight training can build muscle and make you just as strong as lifting heavy weights quickly.
When untrained young men lift weights with different heavy loads but equal total work, their chest muscles grow about the same amount—around 10-11% bigger.
If you do the same total amount of weightlifting work, lifting heavy weights with longer breaks and lifting lighter weights with shorter breaks both build muscle about the same, but lifting heavy gives you more strength.
Lifting heavy weights with fewer reps and longer breaks builds more muscle and strength than lifting lighter weights with more reps and shorter breaks in men who already work out.
When you lift weights, doing a few heavy reps makes you stronger, doing lots of light reps helps your stamina, and doing a medium amount builds bigger muscles.
Lifting weights until you can't lift anymore makes muscles grow bigger no matter how heavy the weights are, but using heavier weights builds more strength than lighter ones.
When people who are already fit push themselves as hard as they can during weight training, it doesn't matter if they lift heavy weights for a few reps or lighter weights for many reps—both ways build muscle about the same.