Browse evidence-based analysis of health-related claims and assertions
Doing partial reps with extended muscle stretch and full reps with normal movement build your arm and thigh muscles about the same amount over 12 weeks — neither one is clearly better than the other.
Descriptive
No one has studied whether doing exercises with a full or limited range of motion makes your core muscles grow bigger, so we don’t know the best way to train them for muscle growth.
Some studies say doing arm exercises with shorter movements builds more muscle in the triceps, while others think full movements might help the biceps more—but we just don’t know for sure what’s best yet.
When you do full-range exercises like deep squats, some leg muscles like your inner thighs and butt grow more than others, but your front thigh muscles don’t seem to care whether you go deep or not — not all muscles react the same way to how far you move.
Doing full squats or full arm movements when lifting weights doesn’t necessarily make your thigh muscles grow bigger than doing partial movements—studies show both ways work about the same, so going all the way down or all the way up might not give you extra muscle gains.
If you lift weights through a full movement range—like squatting all the way down and up—you’ll build bigger leg muscles than if you only half-squat, especially if you’re new to lifting and male.
Causal
If older adults who’ve had a stroke or have high blood pressure switch from normal salt to a special salt with less sodium and more potassium, they might live longer.
If you're over 65 and have had a stroke or high blood pressure, switching to a special salt that has less sodium and more potassium might help lower your chances of having another heart attack or stroke.
If you're 65 or older and have had a stroke or high blood pressure, switching to a special salt that has less sodium and more potassium might help lower your chances of having another stroke.
When adults with severe kidney disease get a new kidney, their heart often gets healthier—especially the thickened walls and enlarged chamber—but men and women don’t improve in exactly the same way or to the same degree.
Women with kidney disease who are getting a new kidney tend to have bigger and less flexible heart chambers before the surgery than men, which might mean their hearts have been working harder for longer.
After a kidney transplant, men’s heart pumping ability improves more than women’s, even though women’s hearts were already pumping better to start with.
Correlational
After getting a new kidney, women’s hearts show more improvement in a specific heart measurement than men’s, even though women started with a larger heart size — suggesting their hearts recover differently based on sex.
After a kidney transplant, men’s hearts tend to shrink back to a healthier size more than women’s hearts do over six months—even though men’s hearts were bigger to begin with—suggesting that men and women’s hearts respond differently to the transplant.
Lifting weights through a shorter movement range can build muscle just as well as lifting through a full movement range — no difference in muscle growth.
Quantitative
If you're already eating enough protein, taking extra leucine won't help you build more muscle.
If you swap regular table salt for a salt substitute that has more potassium, it might lower your chance of having a stroke by about 14%.
After getting a new kidney, women’s hearts don’t shrink as much in size as men’s hearts do.
Taking creatine monohydrate won’t help trained rowers do more reps during weight training or maintain higher power during repeated rowing sprints.
If trained rowers do six weeks of intense rowing and weight training, they’ll get stronger, row faster, and lose fat or gain muscle—even if they don’t take creatine supplements.
Taking creatine powder while doing intense rowing and weight training won’t make you stronger, faster, or change your body composition any more than taking a sugar pill instead.
After lifting weights, your muscles make more of a protein called Cyclin D1 quickly — not by turning on new genes, but by using existing instructions more efficiently, which might help your muscles adapt and grow.
Mechanistic
Even after working out with weights for 8 weeks, your muscles still respond to a single workout the same way as they did at the start—your body doesn’t get better at signaling muscle growth after training for a while.
After working out with weights for 8 weeks, your body keeps its protein-making machines more active even when you're resting, as if it's always ready to build more proteins.