Browse evidence-based analysis of health-related claims and assertions
Whether you rest 1 minute or 2 minutes between squat sets, your muscles get about the same amount of oxygen during the exercise, even if you're at high altitude or breathing normal air.
Descriptive
People feel much more tired after doing weightlifting with only 1 minute of rest between sets than with 2 minutes of rest, no matter if they’re at high altitude or breathing oxygen-poor air.
Causal
Whether you rest 1 minute or 2 minutes between sets, or train at real high altitude or with a mask, you can still lift the same total amount of weight without losing strength.
Even when the air has the same amount of oxygen, breathing it through a mask at low pressure makes your body produce less lactic acid and keeps your heart rate lower during weightlifting than being at real high altitude.
Breathing air with less oxygen through a mask (simulated altitude) makes your muscles get less oxygen during exercise than being at real high altitude, even when the oxygen level in the air is the same.
Taking less rest between sets of weightlifting makes your body work harder, raises your heart rate, makes your muscles burn more lactic acid, and feels much more exhausting.
If you're already someone who lifts weights, doing light weights twice a week until you can't do more reps can make your muscles bigger and stronger in just 8 weeks.
For people who already lift weights, it doesn’t matter much if you rest 30 seconds or 2.5 minutes between sets of light weights — you get the same muscle growth and strength gains either way.
Quantitative
You can get stronger and bigger muscles by lifting light weights until you're exhausted — even if you never lift heavy, which challenges the old idea that heavy weights are required.
Mechanistic
Whether you rest a short or long time between light weightlifting sets, your body releases about the same amount of growth-related hormones right after the workout.
Resting 30 seconds between sets of light weights builds your arm and leg muscles just as well as resting 2.5 minutes — at least in people who already train regularly.
If you're already trained, doing light weights with short or long breaks between sets gives you about the same strength boost in your chest and legs after 8 weeks.
Even though your body releases similar growth hormones after light workouts whether you rest a little or a lot, you still get stronger and bigger muscles either way.
Whether you rest 30 seconds or 2.5 minutes between sets of light weightlifting, you end up with about the same muscle growth and strength gains after 8 weeks.
Even light weightlifting until exhaustion makes your body release hormones that are linked to muscle growth, no matter how long you rest between sets.
Lifting light weights until you're exhausted can make you stronger at lifting heavier weights, even if you never lift heavy.
Even lifting light weights really slowly until you can't do another rep can make your muscles bigger, just like lifting heavy weights.
When researchers measured the thickness of the upper arm at two specific spots, both spots got thicker after 12 weeks of arm workouts.
After doing bicep curls 24 times over 12 weeks, women’s upper arm muscles got noticeably thicker, no matter which way they did the curls.
After 12 weeks of training with the same total workload, neither method made the biceps noticeably thicker than the other.
Women who did any kind of upper-body strength training ended up with thicker biceps than women who didn’t train their upper body at all.
Doing bicep curls with two different methods—either lowering the weight gradually or keeping it heavy—both made the upper arm muscles thicker in young women after 12 weeks of training.
Only five small studies were used, with just 120 people total — so the results are too shaky to be very confident about.
We can’t say whether light or heavy weights are better for growing muscle fibers in the thighs — we just don’t have enough good data yet, and we need more studies with more people.