Browse evidence-based analysis of health-related claims and assertions
Switching up your shoulder position during bicep curls makes your muscles fire more, even if you're lifting the same total weight.
Causal
Whether you change your shoulder angle or not during bicep curls, your muscles recover at the same speed over the next three days.
The middle part of your bicep gets a little more 'hazy' on ultrasound after a workout, but it clears up by the next day — and it doesn’t matter if you changed your shoulder angle.
When you do bicep curls with your shoulder stretched back, the lower part of your bicep shows more signs of stress on ultrasound right after the workout than when you keep your shoulder neutral.
After a tough bicep workout, your arm gets a little swollen, but it goes back to normal by the next day — and it doesn’t matter if you changed your shoulder angle during the workout.
Even when you change your shoulder position during bicep curls, you still lift the same total amount of weight — your total workout effort doesn’t go up or down.
Changing the angle of your shoulder while doing bicep curls makes your biceps work harder during the workout, even if you're lifting the same total weight.
Doing 14 sets vs. 21 sets doesn’t make your muscles look any different on ultrasound—even though you lifted more total weight in the 21-set version.
Correlational
Even after doing 21 sets of squats, you can still lift the same heavy weight two days later—your muscles bounce back fast.
You might feel like you got wrecked after a heavy workout, but your strength and muscle size don’t actually change—your brain is just telling you it was hard.
Even after a brutal leg workout, your muscles don’t get damaged or leak fluid in a way that shows up on ultrasound the next day.
After a really hard leg workout, you feel beat up the next day—but by the day after that, you’re back to feeling normal again.
No matter how many sets you do, your thigh muscles look the same on ultrasound before and up to three days after—so swelling isn’t worse with more work.
Doing more sets means you’re lifting more total weight—simple math, but important for tracking how hard you’re working.
Even after a super hard leg workout, your thighs don’t stay swollen for days—the puffiness goes away by the next day.
Even after doing a lot of squats, guys can still lift about the same amount of weight the next day or two—so one tough workout doesn’t make them weaker right away.
After doing a lot of leg exercises, guys feel less recovered the next day—even if their muscles look fine—because they just feel more tired.
Doing more sets of squats and leg exercises makes people feel like they worked harder, even if their muscles don’t get more swollen or weaker.
We know adding more sets every two weeks worked in this study, but we don’t know if every week or every month would be better.
Descriptive
This study only looked at the front and side of the thigh—so we don’t know if doing more sets helps your front thigh or hamstrings grow more.
Even if you’re already strong—squatting almost twice your body weight—adding more sets will make you stronger, but won’t make your muscles grow more than doing a moderate amount.
No matter how many leg sets people did, their eating habits didn’t change—so differences in muscle growth or strength weren’t because of diet.
Doing a ton of leg workouts takes way longer—about twice as long—which might make people quit because they don’t have enough time.
People who did more sets didn’t lift heavier weights—they just did more reps and sets. The weight stayed the same, but the total work went up.
Quantitative