Health Claims

If you lift the same total amount of weight each week, it doesn’t matter whether you spread it out over one day or three+ days—you’ll still gain about the same amount of muscle, no matter if you’re experienced or if you’re training your arms or legs.

Correlational

The more you lift weights (up to a point), the more muscle and strength you gain—and new studies say it’s a steady climb, not a peak and drop like we used to think.

Quantitative

As people get older, their muscles might not grow as well after weight training because the cellular machinery that builds muscle proteins doesn’t work as hard after a workout.

Mechanistic

Lifting weights makes your muscles bigger and stronger because it turns on a cellular switch (mTORC1) that tells your body to build more muscle proteins.

Mechanistic

When people lift weights and their muscles get bigger, their cells make more of the tiny machines (ribosomes) that build muscle proteins — and the people who gain the most muscle tend to make the most of these machines.

Correlational

If you're new to weight training, doing three sets of each exercise instead of just one will help you get stronger faster — and after about nine weeks, the difference becomes even bigger.

Causal

The more you lift weights (within reason), the more muscle and strength you tend to gain — and recent studies are showing this pattern more clearly.

Correlational

After a tough workout, older people’s muscles might not build new protein-making machines as well as younger people’s, which could be why they don’t get as strong or muscular over time.

Mechanistic

When you lift weights, a specific system in your muscle cells gets activated and tells your body to build more muscle protein, making your muscles bigger and stronger.

Mechanistic

Lifting weights makes your muscles bigger and stronger, and this happens because your muscle cells start making more of the tiny machines that build proteins.

Mechanistic

If you're new to lifting weights, doing a moderate amount of workouts each week will make you stronger faster than doing very few workouts — and you'll keep getting stronger week after week for the first 9 weeks.

Causal

If you lift weights until you can't do another rep, your body feels like you worked harder than if you stopped before failure—even if you did the same total number of reps and sets.

Causal

Even if you do the same total amount of lifting, going all the way to failure still makes you more tired than stopping short — so it’s not just how much you lift, but how hard you feel you’re working and how often you’re pushing that matters more.

Mechanistic

After a regular workout that doesn’t push you to exhaustion, your jumping power bounces back in just 10 minutes—but if you push yourself until you can’t do another rep, it takes at least half an hour to recover.

Descriptive

If you lift weights until you can’t do another rep versus stopping before failure—while doing the same total amount of work—you’ll feel more tired and more worn out during the workout, especially if you’re a regular gym-goer.

Causal

If you lift weights until you can't do another rep during squats, you'll feel more tired and jump lower afterward than if you stopped before reaching failure—even if you did the same total amount of lifting. This drop in performance can last up to half an hour.

Causal

If you do weight training with a break every few weeks to go lighter, you’ll build muscle and get stronger just as much as if you kept pushing hard the whole time — at least for guys who’ve never trained before.

Causal

If you take it easy on your weight workouts for a little while during an 8-week training program, you won’t lose much of your strength gains—you’ll still get stronger.

Causal

If you take it easy on your weight workouts for a little while during an 8-week training plan, your arm and thigh muscles will still grow just as much as if you kept going full force.

Causal

For guys who don’t lift regularly, doing weight exercises doesn’t change a specific body signal (ERK1/2) 30 minutes after working out, no matter how hard or long they train — so this signal probably isn’t what tells their muscles to grow right after a fasted workout.

Mechanistic

When guys who don’t work out lift weights, their muscles turn on a specific stress signal—no matter if they do 1 set or 5 sets. It’s like the signal just needs the weight to be lifted, not how many times they do it.

Mechanistic

When guys who don’t lift regularly do weight training, even doing more sets doesn’t change certain key muscle signals called Akt and mTOR—so those signals must already be maxed out at low workout levels, and something else is driving the bigger changes seen in other muscle signals.

Mechanistic

If untrained guys lift weights on an empty stomach, doing 5 sets of exercise really ramps up a key muscle-building signal in their cells—but just 1 set doesn’t do much, suggesting you need more than a little effort to kickstart muscle growth.

Mechanistic

When guys who don’t normally lift weights do a tough leg workout on an empty stomach, their muscles show a big spike in two specific signals that tell the body to build more muscle, and this might mean doing more sets makes those signals even stronger.

Mechanistic