Your Muscles Don't Always Need a Day of Rest Between Workouts

If you’re trying to build muscle, conventional wisdom has it that you can't work the same muscle groups two or more days in a row. That is, if you do a full-body workout on Monday, wait until Wednesday before doing the same thing again. Your muscles need at least 48 hours to recover and grow, which they can’t do if you’re training them every day.

Or at least, that’s what we used to think. In fact, the latest science shows that your muscles can recover a lot more quickly than was once believed. Here’s what it all means for you and your workouts: Earlier this year, a team of researchers from Brazil published the results of a very interesting experiment.

They rounded up a group of guys who’d been training for at least three years, could squat at least 150 percent of their bodyweight, and bench press at least 100 percent of their bodyweight.

The men were split into two group and trained five days a week, Monday through Friday, for eight weeks. Both groups followed the exact same training program—same exercises, sets, and reps— but with one key difference.

Lifters in the first group hit different muscles on different days—chest and triceps on Monday, legs on Tuesday, back and biceps on Wednesday, and so on. Each muscle was trained directly once a week. Group two, on the other hand, trained their whole body in every workout.

The study was set up in such a way that the amount of training performed by both groups was identical. In other words, the total number of weekly sets was the same, it was just spread out differently. The once-a-week group did two exercises per workout for 5 to 10 sets per exercise, while the full-body group did 11 exercises for 1 to 2 sets per exercise. Which group do you think gained the most muscle?

The researchers found no significant differences in terms of strength or size gains between the two groups—10 to 15 sets distributed over the course of five days increased muscle mass and strength similarly to the same number of sets performed once a week.

Of course, these are the results from just one study. One swallow does not a summer make, as the saying goes. You can’t come to a strong conclusion on anything based on the results of one study. However, there’s plenty of research out there showing that your muscles can recover and grow quite happily even with just 24 hours of rest between workouts.

In one study, researchers from the University of South Florida compared two training programs that involved squatting and bench pressing three or six days per week. In each workout, the three-day group did four sets per exercise, while the six-day group did two sets. Deadlifts were done twice a week in the six-day group, and once a week in the three-day group.

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The result? After six weeks, there was no significant difference in strength or size gains between the two groups. Benching and squatting six days a week led to gains that were on par with doing those same lifts three days a week. Interestingly, the six-day group did see faster gains in muscle mass—5.7 pounds versus 3.7 pounds in the three-day group. There’s more.

Training on three consecutive days has been shown to build just as much muscle as inserting a day of recovery between each workout. For the study, scientists recruited 30 healthy men and split them into two groups. In each workout, both groups performed three sets of 10 reps on the leg press, lat pulldown, leg curl, shoulder press, and leg extension for each session.

The first group lifted weights three days a week, but all three workouts were done consecutively (e.g. Friday, Saturday, Sunday). Group two also trained three times per week, but the workouts were done on non-consecutive days (e.g. Monday, Wednesday, Friday). Both sets of lifters gained muscle and got stronger, with no significant differences between the two groups.

In other words, training three days in a row then taking four days off produced much the same results as training every other day. Here’s how the researchers sum up their findings: "For individuals who perform 2 to 3 consecutive days of resistance training per week, such as weekend warriors due to time constraints, they should not hold back for fear of inferior or detrimental adaptations if weekly volume and intensity are appropriate."

So, what does all of this mean for you? Well, it doesn’t mean that training each muscle group 5 to 6 times a week is the new official “best way” for everyone to train. The “optimal” amount of time between workouts for the same muscle group is highly individual, and will vary from person to person, depending on the type of training you’re doing and how long you’ve been lifting weights.

However, the results from these studies do suggest that you can be a lot more flexible about how you set up your training program.

If, for example, you’re pressed for time during the week, hitting the gym on Friday, Saturday, and Sunday is a perfectly acceptable alternative to training on Monday, Wednesday and Friday.

Maybe you just prefer 4 or 5 shorter workouts rather than 2 or 3 longer ones. Again, these findings suggest that spreading the work across shorter, more frequent sessions will do the job just as well. If you’ve got a few years of training behind you, and your gains have slowed down or even dried up completely, it’s worth experimenting with working your muscles more frequently to see how your body responds.

Research shows that newbies seem to build muscle just as quickly whether a muscle is trained once or three times per week. However, studies on well-trained subjects show that a muscle will grow more quickly when it’s a trained five days a week compared to training it once a week.

The general message, then, is that you don’t need to worry if your muscles only get 24 hours of rest between workouts. Provided those workouts are set up properly, your muscles appear to be ready for action a lot sooner than was previously believed.

Christian Finn is an exercise scientist and personal trainer based in the UK.

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