Building strength and muscle comes with huge payoffs for health and longevity, but most Americans still don't lift weights or regularly practice any muscle-strengthening activity.
Why? People often blame a lack of time.
Exercise physiologist David Behm says often when he talks to people about resistance training they seem to think they'd need hours in the gym to get results, working through rows of machines targeting each muscle.
"They're like 'my God, I'm going to be in there for an hour and a half or longer," says Behm, a professor at Memorial University of Newfoundland in Canada.
The reality is much different, and it's why Behm and others in his field have started promoting the idea of a minimum dose — as in how little you can get away with and still make meaningful progress.
"We're thinking about the person who is resistance-training averse," he says. "They really don't want to be in there very long."
The evidence shows you can make real gains in strength and muscle with as little as one or two quick workouts a week — depending on the approach, you might be able to get away with as little as a half hour in the gym (or even less).
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The key is focusing on what are called multi-joint exercises, or compound lifts.
These are efficient movements that recruit one or more major muscle groups simultaneously. Some examples are the squat, deadlift, bench press, row and overhead press, or alternatives that can be done on machines.
Behm and his colleagues reviewed data from studies on resistance training and concluded that a beginner could start with one workout a week for the first three months. This kind of routine would incorporate a handful of multi-joint exercises, doing one set of about 6 to 15 reps for each movement.
"After that, if you have more time and want to get better, then work out twice a week, or move to two sets," he says.
Research does show a dose-response relationship between how many sets you do and muscle growth, meaning doing more can give you better results.
But "it's not linear, where it just goes up and up," says Brad Schoenfeld, a professor of exercise science at Lehman College in the Bronx. "You see the biggest increase in the first few sets, and then you see it leveling off."
While a minimalist strategy won't necessarily deliver maximum strength or muscle, Schoenfeld says you can make "very good gains" and see measurable health benefits with an hour to an hour and a half a week of training.
Based on his analysis, he suggests aiming for two separate workouts — each about 30-45 minutes — and a total of 4 to 6 sets per muscle group over the course of the week.
All of this can vary depending on your individual goals and how your body responds.
But for any minimalist approach to be effective in the long run, the research shows you do need to push yourself hard while training, says James Steele, a U.K.-based exercise scientist. The intensity of each workout is key.
"Effort is probably the more important determinant," he says. "It should feel like it's hard work to actually try and move that weight."
In resistance training, effort is usually measured by how close you are to failure, meaning the point where your muscles are so taxed they stall out and you have to stop and rest.
It doesn't seem like you need to go entirely to failure to get results, but you should be within a few reps or so.
And provided you do that, you might be able to get away with even less time in the gym. In a massive study, Steele collected close to seven years of data from nearly 15,000 people.
Their workout regimen? A handful of exercises performed on machines just once a week for about 20 minutes.
The typical participant got anywhere from 30% to 50% stronger in the first year and those gains were maintained or slightly improved upon throughout the study.
The bottom line, says Steele, is that you don't need to spend hours working out, but you do need to be regular.
"Pick a program that you enjoy, do it consistently. You still need to train hard. You can't avoid it," he says. "But other than that, you have a lot of freedom."
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