Browse evidence-based analysis of health-related claims and assertions
Doing strength training twice a week for three months might help women with myotonic dystrophy type 1 get stronger in their legs — and some of that strength could last even after they stop exercising for up to six months.
The big chest muscle has two parts: one on top with smooth, even fibers, and a lower part made of 6 or 7 separate bundles, where the bottom one folds forward.
If you spread your workouts over more days each week but keep the total work the same, you'll get stronger—but your muscles won't necessarily grow bigger.
Doing just one set of each exercise can still help build muscle, even if you're already fit — and it saves time.
If you're new to working out, both parts of your chest muscle might grow about the same when you lift weights.
If you lift weights until your muscles can't do another rep, it helps scientists measure muscle growth in a consistent way over time.
People might respond differently to how much weight training they do, but we can't say for sure because the studies done so far aren't clear enough.
Putting together lots of small studies gives a better guess about what's really going on in the whole population than looking at just one small study.
When a study doesn't include enough people, the results might just be due to chance and not reflect what's really going on for most people.
The more you lift each week for a specific muscle, the more it grows—but after a point, doing even more doesn't help much.
If you're new to lifting, doing three sets of an exercise might not build more muscle than just doing one set—as long as you push each set to the point where you can't lift anymore.
If untrained young guys do pec deck workouts three times a week for three months, following a specific plan, their chest muscles get noticeably thicker—by about 17 to 21%—in both the upper and lower parts of the chest.
If you're new to lifting, doing just one set of pec deck exercises three times a week can make you just as strong as doing three sets — after 12 weeks, both groups get about 45% stronger.
If you're new to working out, doing just one set of chest machine exercises three times a week gives about the same muscle growth as doing three sets — both lead to around a 20% bigger chest muscle after 12 weeks.
In dead bodies, the chest muscle doesn't twist, which might make it easier for surgeons to rebuild it during operations.
The upper part of your chest muscle has fibers that are angled more than the lower part, which might mean they pull in slightly different ways and work differently when you move.
The chest muscle has different parts with different fiber lengths — in one part, fibers get longer from top to bottom, and in another part, the middle fibers are the longest, which might mean they work differently when you move.
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 the tendon works and how well it heals after injury.
The chest muscle in dead bodies has a top part that's smooth and a bottom part made of 6 to 7 separate chunks, where the lowest chunk wraps around the one above it like a cradle — this unique shape might change how the muscle works and how doctors fix it in surgery.
If you're a middle-aged adult with extra weight, eating either a low-carb high-fat diet or a low-fat diet with fewer calories can help you keep your muscle while losing weight over about 4 months.
In middle-aged people who are overweight, eating fewer carbs and more fat for 15 weeks might help their body respond better to insulin, while cutting calories on a low-fat diet could actually make insulin work worse — and these changes happen even if both groups lose about the same amount of weight.
Eating fewer carbs and more fat—without counting calories—can help people lose about as much weight as eating less fat and cutting calories. This suggests that what you eat might matter just as much as how much you eat.
If you're middle-aged and your body doesn't respond well to insulin, cutting carbs and eating more fat might help you lose belly fat better than a low-fat diet. But if your body handles insulin normally, both diets work about the same for fat loss.
For middle-aged people with extra weight, cutting carbs a lot might burn more belly fat — especially the dangerous kind around organs — even if you lose the same total weight as someone on a low-fat diet.