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Science Why Just 13 Minutes of Strength Training Could Be Better Than Spending Hours in the Gym

A 2019 study looking at muscular adaptations finds a sweet spot when it comes to training volume and time.

Woman working out at home on Tonal for muscular strength and hypertrophy.
  • Research indicates that you can see muscular strength gains with just three 13-minute sessions per week.
  • The study suggests there’s no single “right” way to exercise for muscle growth, experts note.
  • In addition to a structured weight-training program, adding variety to your fitness routine can be beneficial for muscular strength.

If you’ve always thought you’d have to spend hours working out to build strength, think again. Research published in Medicine & Science in Sports & Exercise shows that you can start gaining strength in just 13 minutes, three times a week.

For the study, researchers set out to determine the impact various set and repetition combinations would have on muscular strength, endurance, and hypertrophy (muscle growth). They looked at 34 healthy, resistance-trained men and split them into three groups according to training volume: The low-volume group performed one set per exercise training session; a moderate-volume group did three sets; and a high-volume group completed five sets. Training for all groups consisted of three weekly sessions on nonconsecutive days for eight weeks.

At the end of the study, all three groups saw significant improvements in muscular strength and endurance gains. Surprisingly, the low-volume lifters enjoyed the same improvements as those who spent five times as long working out. The only difference between the high and low groups was muscle growth. While all the study participants experienced some increase in muscle size, those lifting higher volumes saw bigger changes.

One of the most prominent takeaways from the study is that there is no single “right” way to exercise for strength, and the goal is to be consistent and challenge the muscles to the point of fatigue, according to Pete McCall, NASM-certified Master Trainer, author of Smarter Workouts: The Science of Exercise Made Simple, and host of the “All About Fitness” podcast.

To use exercise to maintain health, those three 13-minute sessions may be enough, and McCall says if your schedule is packed, then 13 minutes is better than nothing. “Here’s where having equipment to exercise at home is a benefit, so when you’re busy, you have that option,” he adds.

The study has obvious limitations, he adds, most notably in the small number of participants and the lack of women. But McCall believes the results would be applicable to many people, both men and women, because the mechanism would still apply.

In terms of understanding how to get muscle growth with more efficiency, it’s first necessary to back up and take a look at the two ways to achieve that growth, he says, and that’s through either structural damage caused by mechanical overload or by metabolic fatigue. Both require exercising to the point of fatigue—meaning not being able to complete even one more rep—and that can be achieved in a 13-minute workout if you’re doing four to six different exercises to get to that point, explains McCall. 

“Hypertrophy means increasing muscle fiber size, and reps to the point of fatigue will create structural damage to muscle fibers,” he notes. “This initiates a repair process with hormones to repair damaged tissues.”

Hypertrophy can generally be achieved by performing 10 to 20 reps to the point of fatigue, he adds, and studies have shown that lighter weights can cause hypertrophy, but the reps still need to be performed to failure, which could be 25 to 30-plus reps if the weight is too light. McCall says that can get tedious as well as time-consuming. 

He adds that both of these approaches can be achieved with Tonal, and the goal is to cause fatigue in 10 to 20 reps. Keep in mind, too, that there are other factors that play important roles, including nutrition, hydration, and rest. 

Another part of gaining efficiency in achieving strength goals is variety, adds Tony Horton, creator of P90X and a Tonal guest coach. While sticking to a 13-minute, three-times-weekly routine can help you progress, broadening your fitness efforts in general along with that can be helpful, he believes.

“Weight training, bodyweight training, HIIT, plyometrics, yoga, core exercises, cardiovascular training, and whole foods all work in concert to give just about everyone a fighting chance to get strong, be flexible, and feel amazing,” he says.