Health Claims

If you're already strong and experienced, you can choose to do either full reps or half-reps at the stretch — both will make your arms bigger and stronger about the same amount.

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

Going all the way up and down doesn’t help you build more muscle than just going halfway down and staying in the stretchy part — the stretch is what matters, not the top part.

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

It doesn’t matter if you go all the way down or stop halfway — as long as you stretch your muscles fully at the bottom of the movement, you’ll build just as much arm muscle.

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

Whether you do half-reps or full reps when doing lat pulldowns, your ability to do more reps with the same weight improves about the same amount after 8 weeks of training.

Causal

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 experienced with weightlifting, doing half-reps at the stretched position works just as well for building arm muscle as doing full reps — neither is clearly better.

Causal

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

About 4 in 10 adults in this Colombian study had metabolic syndrome, especially women, older people, city dwellers, and those with less schooling.

Descriptive

How strong you are for your body size matters more for metabolic health than how strong you are overall—being strong for your weight is better than just being strong.

Correlational

The worst metabolic health is seen in people who have both a big waist and weak muscles for their size—this combination is a much stronger warning sign than either one alone.

Correlational

People who are weaker for their body size—measured by how hard they can squeeze a handgrip device—are more likely to have multiple metabolic health issues like high blood sugar and bad cholesterol.

Correlational

People with bigger waistlines are much more likely to have multiple health problems like high blood sugar, bad cholesterol, and high blood pressure.

Correlational