Health Claims

After a hard bike ride or run, eating lots of carbs for a few days almost always makes your muscles store more energy than before—even if the amount varies.

Descriptive

If your muscles already have a lot of stored energy before you start exercising, they don’t store as much extra energy afterward—even if you eat lots of carbs.

Correlational

The more you deplete your muscle energy stores during a hard bike ride, the more your muscles can overfill with energy afterward when you eat carbs.

Correlational

When you eat a higher percentage of your calories from carbs (like 80% vs 60%), your muscles store more energy after a hard bike ride—even if you’re eating the same total amount of carbs.

Correlational

After biking really hard and then eating a lot of carbs for a few days, your muscles store way more energy than they do after running hard and eating the same way.

Quantitative

If you're already strength-trained and do upper-body workouts for 8 weeks, it doesn't matter much if you lift all the way up and down or just do part of the motion—your muscles grow and get stronger about the same either way.

Causal

Even after a really tough weightlifting session, your muscles don’t run out of fuel fast enough to slow you down, and they can refill just fine even if you don’t eat carbs for a while.

Mechanistic

If you're already strength-trained, doing full lifts (like fully curling a dumbbell) won't make your muscles grow more than just doing the stretchy part of the movement—so maybe stretching your muscles under load is the real secret to getting bigger.

Causal

Eating carbs before a workout when you haven't eaten all night might make you feel like you can lift more—but it's probably because you feel less hungry or think you're getting energy, not because your muscles actually have more fuel.

Mechanistic

If you're lifting weights and stretch your biceps and triceps really far—like at the bottom of a curl or overhead extension—you'll build muscle just as well as if you move all the way up and down, as long as you get that deep stretch.

Causal

Whether you eat a lot of carbs or very few, as long as you're getting enough calories and protein, your strength and muscle growth won't be different after 3 months of lifting weights.

Correlational

If you're already strong and you train your back with either short or full movements on the lat pulldown machine for 8 weeks, you'll get just as much better at doing more reps with the same weight—no matter which style you pick.

Quantitative

If you're doing a really long, intense workout with lots of sets, or working out twice in one day, eating carbs might help you lift more—but only if you were hungry or hadn't eaten, not if you're eating the same number of calories from other foods.

Correlational

Eating carbs before or during a normal weightlifting session doesn't make you stronger or let you lift more reps, as long as you've eaten recently and aren't doing super long workouts.

Correlational

If you're already strength-trained, doing arm exercises with only part of the motion (like half-bicep curls) builds your arm muscles just as much as doing the full motion — and the data suggests there's probably no real difference between the two.

Quantitative

Working your muscles when they’re stretched out—either fully or at the start of the movement—helps them grow best in your thighs, biceps, and triceps.

Descriptive

Doing arm extensions only in the middle part of the motion makes your triceps grow more than doing the full motion.

Descriptive

If you only do the first half of a leg extension, your upper thigh muscle grows more than if you do the full motion.

Descriptive

When you squat or move your legs widely, your butt and inner thighs grow more than if you only do the last bit of the movement.

Descriptive

Doing exercises through a full motion or starting the movement with a shorter motion (but not ending with it) helps your muscles grow more in your thighs and biceps than doing only the last part of the movement.

Descriptive

Even though drinking whey protein makes more building-block amino acids show up in the blood during extreme dieting, those amino acids don’t get the muscle to grow like they normally would.

Descriptive

Even when the body is in starvation mode, one specific part of the muscle growth system (4E-BP1) becomes more active — which is confusing because other parts are shutting down.

Descriptive

When people eat way less food and exercise a lot for a few days, their body lowers the hormones that help build muscle and raises the stress hormone, which may explain why their muscles stop growing even if they eat protein.

Descriptive

Even when people eat whey protein during extreme dieting and lots of exercise, their muscles stop responding to it like they normally would — the protein doesn’t trigger the usual growth signals.

Mechanistic