One and Done?
Research also suggests that a once-weekly strength training frequency can be just as effective on improving muscle strength as a more rigorous schedule . This small study followed two groups of adults over 60—one group performing a set of strength training exercises to muscular fatigue once per week, and a second group that exercised twice per week—and found that substantial strength gains can be derived from less frequent activity.
Trainers agree there are definite benefits to workouts on a limited schedule.
"I have clients who only strength train once or twice per week, and they still see some significant results in strength," says Noam Tamir, a Greatist expert and founder of Tamir Systems Fitness. "Most of this can be attributed to neural adaptation, which means that your nervous system is adapting to added force, even if nothing is happening to muscle size."
"Full-body functional strength training can be super effective once or twice a week," agrees Jordan Metzl, M.D., a sports medicine physician and author of Running Strong.
In fact, Metzl created a series of programs for runners training for 5K, 10K, half-marathon, and marathon distances that incorporate a strength workout just one day per week. And he's experienced the benefits personally: As Metzl has incorporated one day of functional strength training—think bodyweight exercises—into his own marathon and IRONMAN training plans, he's broken his personal best times.
More from Greatist: 50 Bodyweight Exercises You Can Do Anywhere
To be fair, one or two days of lifting per week is probably not getting you anywhere near those Hulk-esque arms—but that's OK. Strength training isn't just about "bulking up," Metzl explains.
"Instead, it helps your muscles get stronger, improves your balance, and preserves your fast-twitch muscle fibers, allowing your muscles to contract faster." Translation: This helps you drive the golf ball farther, hit an overhead harder, and see improvements in any sport performance.
Strength training also increases endurance, or lactate threshold—the amount of time it takes for your muscles fatigue, Metzl says. This means the amount of exercise you'd have to do to make your muscles so sore you can't use them efficiently (i.e. that painful soreness after hitting the weights when you do so sporadically) increases the more you lift.
An added bonus for people training for endurance races such as marathons or triathlons: Even though their time is already limited, adding anaerobic (strength) training one or two times per week helps the body handle the repetitive stress of movements like running, cycling, or swimming, Tamir adds.
What if you're not doing any sort of exercise outside the one or two trips to the gym?
"For the average person, strength training once or twice a week is enough to break the negative effects of a sedentary lifestyle," says Rebecca Golian, a personal trainer and creator of the Obstacle Course Race Training Program at Chelsea Piers in New York City. "It's enough to stimulate muscle growth, increase cardiovascular strength, and help improve endurance."
The Sweet Spot: Two-a-Weeks
Not all experts agree that strength training only once a week is sufficient, however.
"Strength training twice per week is perfect, but once is a waste of time," Boyle says. "Sure, you can potentially gain strength on one workout a week, but you would continually be sore. Twice a week is less of a shock to the system and allows the body to better adapt."
Research also makes the case for two or three weekly resistance workouts rather than one. One study examined the effects of three different strength training frequencies on 1,725 previously sedentary men and women . The one-day-per-week trainees added 0.7 pounds of lean weight, whereas both the two-days-per-week and three-days-per-week exercisers added 3.1 pounds of lean weight. Another study comparing different strength training frequencies on torso rotation muscle strength had similar results.
Fifteen minutes, twice a week, is the minimum amount individuals can strength train and still see results.
More: 5 Strength-Training Exercises You Should Start Doing Now
