The exact amount of time you need to lift weights to see muscle gains, according to research

Strength training benefits people of all ages. It has a slew of research-backed perks, including improved mental health, brain health, bone density, lower blood pressure, increased lean muscle mass, decreased visceral fat, and a lower risk of Type 2 diabetes. And it turns out, you don’t need to spend hours in the gym to see results, according to recent research.

A small study published in the journal Medicine & Science in Sports & Exercise in April found that people who lifted weights for just 30 minutes, twice a week (which is in line with U.S. Federal Physical Activity Guidelines) were able to increase their muscle mass. The 42 participants (34 men, 8 women) performed nine exercises targeting all major muscle groups for eight weeks. They were divided into two groups: one completed the exercises until they couldn’t do any more repetitions with the right form (training to failure), and the other completed the exercises with two repetitions still left in the tank (reps in reserve).

Researchers found that all of the participants had meaningful muscle growth and improvements in their strength—even though the participants had previously strength trained, and the amount they were working out during the study was lower than some of their usual routines.

“This reinforces the veracity of the claim that a lack of time should not be a barrier to regular participation in [resistance training] programs, even for resistance-trained individuals,” the study authors wrote. “Our findings therefore indicate that resistance trained individuals not only can maintain muscular gains employing low set volumes, but potentially enhance adaptations at least over relatively short training periods.”

Here’s their workout routine

Research shows that over 70% of Americans aren’t hitting the current U.S. Federal Physical Activity Guidelines, which recommend that adults do muscle-strengthening activities of moderate- to vigorous-intensity that involve all major muscle groups on two or more days a week.

During the 8-week study, the participants completed the following exercises:

• Front lat pull-down
• Seated cable row
• Shoulder press
• Chest press
• Cable triceps pushdown
• Supinated dumbbell biceps curl
• Smith machine squats
• Leg press
• Leg extension

If you’re new to resistance training, start at a lower weight or body weight only. Don’t push yourself too hard and risk injury, and slowly progress over several weeks. 

In addition to strength training, the federal guidelines emphasize cardiovascular activity. Adults should aim for 150 to 300 minutes of moderate-intensity physical activity per week (like brisk walking or yard work), or 75 to 150 minutes a week of vigorous-intensity aerobic physical activity (like running or shoveling snow).