Health Claims

When people try to move their arm with a robot and can’t see or feel where they’re supposed to go, they miss the target by a lot—much more than when they get visual or force cues.

Correlational

When people’s arms are moved by a robot without seeing where they’re supposed to go, their muscles don’t work as hard as when they can see the target path—even if they’re not moving on their own.

Correlational

When people use a robot to move their arm along a curved or wiggly path instead of a straight line, their muscles work harder and they make more mistakes, no matter if the robot moves their arm or they move it themselves.

Correlational

When healthy people move their arm with a robot using just one kind of feedback (like seeing a target or feeling resistance), they make more mistakes and use more muscle effort than when they get both kinds of feedback at once.

Correlational

When both arms are moved together by a robot while watching a screen, healthy people’s muscles work harder than when only one arm is moved, even if they’re not trying to move it themselves.

Correlational

When people do a shoulder exercise standing with a resistance band, tennis players and other athletes use their shoulder blade muscles about the same—so this exercise doesn't reveal the differences seen in other exercises.

Correlational

Both tennis players and other athletes have some imbalance in how strongly each shoulder blade muscle works, but tennis players are more balanced when their arms are raised high, and more unbalanced when their arms are at a lower angle—like during a tennis stroke.

Correlational

Tennis players activate their shoulder blade muscles much more when doing a shoulder exercise lying face down than when doing the same movement standing with a resistance band.

Correlational

When tennis players do a shoulder exercise lying face down with arms raised high, their shoulder blade muscles don't fire as strongly as in other athletes—sometimes less than half as much.

Correlational

People who play tennis don't use the shoulder blade muscles as much as other athletes when doing a specific exercise where they lie face down and pull their shoulder blades together, especially when their arms are raised high.

Correlational

While the majority of individuals exhibit similar hypertrophic responsiveness across high- and low-load resistance training, a subset may demonstrate load-specific responsiveness, though such responses are inconsistent and not reliably predictable.

Assertion

Individual hypertrophic responsiveness to resistance training exhibits moderate inter-muscle correlation, but a substantial proportion of variability is attributable to non-exercise-specific biological factors.

Assertion

Total muscle mass recruited during a compound exercise does not determine the magnitude of hypertrophy in a target muscle when compared to an isolation exercise with matched training volume and effort.

Assertion

Muscles that cross two joints (biarticular muscles) exhibit preferential hypertrophy with isolation exercises that target a single joint action, due to mechanical disadvantage during multi-joint movements.

Assertion

Compound exercises involving greater total muscle mass do not produce superior hypertrophy in target muscles compared to isolation exercises when training volume and effort are equated.

Assertion

Resistance training to muscular failure induces equivalent hypertrophy in both slow-twitch (type I) and fast-twitch (type II) muscle fibers, regardless of load or repetition range.

Assertion

When resistance training is performed to volitional muscular failure, hypertrophic outcomes are equivalent across a wide range of loads (from low to high) and repetition ranges.

Assertion

Individual hypertrophic responses to resistance training are highly variable across muscle groups and are not consistently correlated between upper and lower body musculature.

Assertion

For small muscle groups, unilateral and bilateral resistance training produce equivalent hypertrophic adaptations when volume and effort are matched.

Assertion

Unilateral resistance exercises can increase neural drive and muscle fiber recruitment compared to bilateral exercises due to reduced neuromuscular inhibition during single-limb contractions.

Assertion

Older studies showed bigger strength gains from weight training than newer ones, probably because today’s studies are better designed and less biased.

Correlational

Men tend to get stronger faster than women when lifting very heavy weights, possibly due to differences in how their muscles and nerves respond to intense training.

Causal

If you’ve been lifting for a while, doing more workouts over time will help you build more muscle than just lifting heavier weights.

Causal

People who’ve never lifted weights before gain muscle much faster than those who’ve trained before—even if they do the same workout.

Causal