Browse evidence-based analysis of health-related claims and assertions
After hard exercise, zinc levels in runners' blood drop lower than before they started, and this happens even in people who don't exercise much, which might mean their bodies react slowly or lose zinc.
Descriptive
When male runners push themselves to exhaustion during intense exercise, their blood levels of zinc and copper go up right away—even when they eat the same foods—showing it's the body's natural reaction to hard workouts.
If you do the same total amount of exercise, three different workout styles—regular weight training, pre-exhaustion, and drop sets—all work just as well for building muscle strength, endurance, and size.
Causal
Different ways of lifting weights—like regular sets, pre-exhaustion, or drop sets—all work just as well for building muscle strength, endurance, and size if you do the same total amount of work. Changing the method doesn't give you better results.
When endurance athletes push themselves to exhaustion, their jumping ability gets worse in normal or low-oxygen air, but stays the same in hot conditions. This shows that different types of tiredness affect muscles differently depending on the environment.
When endurance athletes push themselves hard in hot conditions, their bodies produce more of one inflammation marker, but when they exercise with less oxygen, they produce less of another inflammation marker—showing different reactions to heat versus low oxygen.
Breathing less oxygen while exercising hard makes endurance athletes tire out faster because it weakens their muscles' ability to work properly, but getting hot doesn't really change how their muscles perform.
When guys who don't usually exercise try a special workout called pre-exhaustion training, they get 17% stronger in their legs—that's more than the 11% boost from regular workouts, probably because the special training targets the muscles more directly.
If untrained adult men do leg press exercises for nine weeks, their butt muscles won't grow much bigger, no matter how they do the exercises.
When untrained men do a specific type of weight training called pre-exhaustion, some parts of their thigh muscles grow more than others—the lower front part grows 44% thicker and the upper outer part grows 32% thicker.
Quantitative
For men who don't exercise much, doing regular leg press workouts with three sets at a moderate weight helps reduce overall body fat and thigh fat more than a different workout method, probably because they do more total work.
A shorter, easier leg workout gives the same muscle and strength gains as a longer, harder one for beginners, even though you're doing less overall work.
Doing a light warm-up set before lifting heavy weights might help you build more muscle and get stronger, according to some research that tried a similar but different approach.
When you tire out a muscle with one exercise before doing a bigger workout, you can't do as many reps in the big workout, so you end up doing less overall exercise than if you just did the big workout alone.
When people do a special workout called pre-exhaustion, some muscles work harder right away, but the main muscle doesn't always get more active. Also, these quick changes don't tell us if the workout will build more muscle over time.
When scientists study a special workout method, they sometimes change how it's done from the original plan, making it hard to compare results and figure out what really works.
Doing a simple exercise right before a harder one with no break doesn't make you stronger or build more muscle better than just doing regular workouts, according to current research.
A study found that doing leg press exercises, whether with a special pre-exhaustion method or the regular way, didn't make the glute muscles grow much in men who were new to training after 9 weeks. This means the leg press machine isn't great for building these muscles.
A specific type of weight training makes leg muscles grow unevenly, with some parts growing much more than others, because different parts of the muscle get worked harder during the exercise.
For guys who don't usually work out, doing regular weightlifting cuts more overall body fat and thigh fat than a special pre-exhaustion method over 9 weeks, probably because you lift more total weight with the regular way.
For guys who don't usually work out, doing a special type of leg exercise first leads to bigger strength gains than regular training over 9 weeks, probably because it targets muscles more specifically and adds extra low-effort reps.
A lighter warm-up exercise before heavier lifting gives the same muscle and strength gains as just doing the heavy lifting alone, even though you're doing less overall work.
This claim says that taking short breaks during sets or dropping weight between sets are useful training tricks for certain situations.
Doing certain types of back-to-back exercises shortens workout time but still builds muscle and strength just as well.