Health Claims

If you're a guy who's been lifting weights for a while, doing squats more often during the week—like four times instead of two—might feel easier and less tiring, especially after a few weeks.

If you're a guy who's been lifting weights for a while, working out each muscle four times a week doesn’t make you stronger than doing it twice a week—as long as you're doing the same total amount of work.

In dead human bodies, the muscle fibers in the upper part of the chest muscle are angled more sharply than those in the lower part — this difference might affect how the muscle pulls and generates strength in each area.

In the chest muscle, the upper part has longer fibers toward the bottom, and the lower part has its longest fibers in the middle — this might mean different parts of the muscle do different jobs.

The chest muscle and its tendon don't twist in human bodies, which might make surgeries to fix them easier.

In dead bodies, the big chest muscle's tendon has two layers—one in front and one in back. The front layer is longer, and they join together at the bottom, which might affect how doctors fix it in surgery and how it handles force.

In dead human bodies, the big chest muscle has a regular upper part and a lower part made of 6 to 7 separate pieces, where the lowest piece bends forward to hold the one above it — a pattern that might affect how the muscle works or heals after surgery.

Splitting data into training and testing sets gives a fair measure of how well a machine learning model works—just as reliable as more complex methods—because it keeps the test data completely separate so the model doesn't cheat by seeing it early.

If a machine learning model has more features (like traits or measurements) than data points (like people or samples), it can 'cheat' by finding fake patterns in random noise, especially when tested the wrong way — making it look better than it really is.

If you pick the most important features using all your data — including the test set — your model might look better than it really is, because it's secretly cheating by seeing data it shouldn't see yet.

Nested cross-validation is like having two layers of checkups when testing a model—it keeps the test data totally separate so the model doesn’t cheat, giving a fairer score no matter how much data you have.

If you're testing a machine learning model using a common method called K-fold cross-validation, you might think it's working better than it really is—especially if you're tuning the model using all your data first. This can trick you into believing your model is accurate when it won't work as well on new data.

For young guys just starting out at the gym, doing 1 set or 3 sets of each exercise gives about the same strength boost in the upper body after 11 weeks.

If you're a new guy to lifting weights, doing 3 sets of leg exercises 3 times a week for almost 3 months will get you way stronger than doing just 1 set — like 41% stronger versus 21%.

If young guys who don’t work out start doing 3 sets of leg exercises instead of 1, they’ll get stronger legs and bigger thigh muscles—41% stronger and 11% more muscle—but their arms and chest won’t see the same extra benefit from doing more sets.

If older women who aren't used to working out do 12 weeks of strength training—using 8 exercises and doing 10 to 15 reps each time—they’ll get noticeably stronger in both arms and legs, gain muscle, and improve key health markers, whether they do one or three sets per exercise.

For older women who don’t usually lift weights, doing one set of each exercise is just as good as doing three sets for getting stronger and building muscle over 12 weeks — more sets don’t seem to help extra at this stage.

If you're a guy who's already used to lifting weights, doing heavy sets with long rests works just as well as doing more reps with shorter breaks when it comes to getting stronger in the squat after 8 weeks.

If you're a guy who lifts weights, doing more reps with lighter weights (which spikes your hormones more) doesn't build more muscle or strength over 8 weeks than lifting heavier weights with fewer reps—even though the hormone changes look different.

In guys who lift weights regularly, doing more reps with lighter weights and short breaks gives a bigger boost in growth hormone early on (by week 3) than doing fewer reps with heavier weights and longer breaks—but by week 10, that difference goes away.

If you're a guy who's already used to lifting weights, doing fewer reps with heavier weights and longer rests might boost your bench press more than doing lots of reps with lighter weights and short breaks — at least over 8 weeks.

If you're a guy who's already been lifting weights, doing fewer reps with heavier weights and longer rests might build more arm muscle over 8 weeks than doing more reps with lighter weights and shorter breaks.

Women with myotonic dystrophy type 1 might feel less pain and notice better leg function after doing a 12-week supervised strength training program.

Doing supervised strength training for 12 weeks might help women with myotonic dystrophy type 1 feel less down or unmotivated, based on how they report their own mood.