Health Claims

Whether you do just compound lifts or add arm isolation moves, both ways help reduce arm fat a little bit — and neither is better than the other.

Descriptive

If you're new to lifting, doing big lifts like presses and squats is just as good for getting stronger as doing those plus extra isolated arm exercises.

Descriptive

Doing extra arm exercises along with big compound lifts like squats and presses makes arms a little bigger, but doesn’t make you stronger than doing just the big lifts alone.

Descriptive

Even if you cheat a little to lift heavier, your muscles still grow just as well—so maybe the key to building muscle isn’t perfect form, but just getting your muscles to work hard enough.

Mechanistic

Even though people who swing weights use their whole body more, their upper arms don’t get any thicker than those who lift strictly—so the extra movement doesn’t help build more arm muscle.

Causal

Whether you lift your arm weights slowly or with a little swing, your biceps and triceps both get noticeably bigger after eight weeks of training—your triceps grow even more than your biceps.

Descriptive

People who swing the weights while doing arm exercises can lift a lot more total weight over time than those who do it slowly and strictly—even though both groups end up with the same size arms.

Quantitative

When beginners do arm curls and triceps exercises with a little swing to lift heavier weights, their arms grow just as much as when they do the movements slowly and strictly—even though they lift way more total weight with the swing.

Causal

Whether you take short breaks between reps or not, your body adapts by lifting heavier weights at about the same rate—as long as you’re pushing yourself to near failure each set.

Quantitative

Even though both muscle thickness and total lean mass went up after training, they didn’t change together in a predictable way—meaning one might not be a perfect stand-in for the other.

Correlational

If you’re already experienced with weightlifting and train your legs twice a week for 8 weeks with hard sets, your muscles will grow whether you take short breaks between reps or not.

Quantitative

Even though cluster sets let you rest briefly between reps, they don’t actually let you lift more total weight over time than regular sets—if you’re pushing just as hard in both.

Quantitative

When people who already lift weights do either short breaks between reps (cluster sets) or long continuous sets (traditional sets), both ways make their muscles grow about the same amount if they work just as hard and do the same total number of reps.

Quantitative

Muscles don’t grow evenly—when you train your thigh, the top and middle parts of the front muscle grow more than the bottom, and the side muscle grows the same everywhere.

Descriptive

Even though drop sets make your thigh muscle grow more in some spots, they don’t make you stronger in a one-rep max or in a machine test than regular sets—both methods improve strength about the same.

Causal

Doing leg extensions with drop sets (going to failure, then lowering the weight and going again) makes the front part of your thigh muscle grow more than doing regular sets, but only in the upper and middle parts—not the bottom or the side muscles.

Causal

People didn’t lift more or less depending on whether they took creatine before or after their workout — they did the same amount of work in both cases.

Descriptive

Doing strength training with heavy weights for two months makes your muscles bigger and stronger, no matter when you take creatine.

Causal

Taking creatine before or after your workout doesn’t make a difference in how much muscle you build or how much stronger you get, as long as you take it regularly for about two months.

Causal

For women just starting weight training, how much they lift (total volume) matters a lot—but only if they also eat enough protein and calories. It’s the combo that makes a difference.

Correlational

If young women who are new to weightlifting eat enough calories (35–45 per kg of body weight), they get stronger from training—but if they eat too few (15–20 kcal/kg), they might actually lose strength even while training hard.

Correlational

When young women who are new to weight training do more sets and lifts, and eat at least 1.5 grams of protein per kilogram of body weight, they tend to gain more muscle than those who don’t get enough protein.

Correlational

When you lift light weights until you can't go on or until you slow down, your muscles swell and your blood gets more acidic in the same way — meaning your body reacts similarly to both methods.

Causal

Using light weights until you're exhausted or slow builds your muscle stamina better than heavy weights, but doesn't make you as strong as lifting heavy weights.

Causal