How to plan the most time-efficient strength-training workout, according to science

Discovering what's known as your one-rep max, or 1RM, is important, experts say. It's the maximum weight that you can bench, deadlift, or squat if you're trying to add muscle and strength.

To achieve the fastest rate of muscle growth, you should train at a specific percentage of that one-rep max, putting stress on a muscle over a particular amount of time, Nicholas Gill, the strength and conditioning coach for the New Zealand rugby team, told Men's Health.

To calculate your 1RM for your upper body, try to find the heaviest weight you're able to bench, deadlift, or squat four to six times. Use that number in place of "4-to-6RM" in this equation, developed by researchers at the University of New Mexico: (4-to-6RM x 1.1307) + 0.6999. For your lower body, use this formula: (4-to-6RM x 1.09703) + 14.2546.

Then use the resulting value, your one-rep max, to determine how much weight to use in regular workouts. Exactly how much weight depends on your goal. If you want to build explosive power—like for boxing, jumping, or throwing a ball—aim to work out with half of that 1RM, Gill says. For endurance, aim for 70% of your 1RM; to build muscle, use 80%.

One of the reasons people most often give for why they skip exercise is a lack of time. So the 2021 study "No Time to Lift? Designing Time-Efficient Training Programs for Strength and Hypertrophy: A Narrative Review" looked at time-efficient training programs.

Its authors say doing more work per session, called "training volume," is more important than "training frequency," which is how often you work out. To build muscle mass, they recommend performing a minimum of four weekly sets for each muscle group, using the heaviest weight you can lift for between 6 and 15 reps.

Don't feel as if you have to lock yourself into a particular training routine. In fact, the Sports Medicine researchers explain that you can train in one longer session or several shorter ones, whichever better suits your schedule.

Even very short and frequent workouts might be an alternative for those uninterested in longer training sessions—but the authors caution that there are few study results.

Another way to make your training more efficient for time, they say, is to only stretch and warm up the muscles you'll be using in the workout, rather than a general whole-body stretch and warm-up.

Rest-pause training, supersets, drop sets, and other advanced training techniques can cut training time in half compared to traditional training. That's because they more efficiently provide the same overall amount of work for your muscles. They say the techniques are probably better at increasing muscle size rather than muscle strength, however, and more research is needed.

Additional reporting by Emma Rubin. Story editing by Jeff Inglis. Copy editing by Tim Bruns.