How often should you lift weights to get good muscle growth? What’s the optimal frequency of workouts? While many fitness writers and bodybuilding websites say you should get to the gym many times a week, we’ll take a look at some evidence that once a week workouts are as good as three a week.
In a recent article, we saw that brief workouts produce significant strength gains. These workouts lasted only about 15 minutes, and were done twice a week. Maybe it’s possible to decrease the frequency too.
In a study of resistance training, a group of older men and women, age 65 to 79, were randomized to exercise programs of one, two, or three days a week. The program consisted of three sets each of eight different exercises. Note that the study calls it “high-intensity resistance training”, but given the number of sets done, it seems doubtful that it was what is normally referred to as high intensity. I suspect what was meant is that they just worked hard.
The study lasted 24 weeks, or almost 6 months.
Results: there was no difference in muscle strength gains between any groups. Once a week was as good as two or three. Unfortunately, the abstract doesn’t state changes in body composition, although it does say that chair-rise ability was correlated to lean mass gains, and there was no difference between groups.
Another, more recent study found no difference in strength gains in older adults whether they worked out once or twice a week. This study lasted only 9 weeks.
Yet another recent study comparing twice a week with three times a week workouts in adults over age 60 found:
Chest press strength increased in both the 2 times/week and 3 times/week groups over the 8-week training period by 20.84% and 20.18%, respectively. Lower-body (leg press) strength also showed improvements in both groups: 22.34% in the 2 times/week group and 28.12% in the 3 times/week group. There was a slight, but nevertheless significant gain of lean body mass from pre- to post-training (2.4% and 1.9% for the 2 days and 3 days groups, respectively). However, functional performance remained unchanged in the groups. We found that short-term resistance training 2 times/week or 3 times/week elicited comparable muscle strength and lean body mass adaptations in older adults.
Are there any studies showing greater gains with higher frequency training? Yes, at least one. However, it found increased strength gains only in half the exercises (knee extension and curls), while bench press and standing calf raise were the same for both.
Conclusions and caveats
What are we to make of all of this?
All of the participants in these studies were older people. Perhaps it’s possible that younger people would have had different results.
It’s doubtful that many actual bodybuilders work out once a week. But who knows — maybe they could.
Another issue is that of intensity, arguably the most important variable in training for muscle growth. If the participants were not training at high intensity, then volume becomes more important, and perhaps frequency less so. This study argues for higher volume being more important than higher frequency.
My own workout routine uses a two-way split, and I train twice week, and therefore exercise each muscle group only once a week. However, there’s a lot of overlap between muscle groups, e.g. you can’t work out the chest without using shoulders, or do rows without training arms. So in fact some muscle groups get trained more than once a week.
I’m unsure what definitive conclusions we can reach regarding those of us who want maximum muscle gains. While genetics and diet are important, and most or all competitive bodybuilders use PEDs, maybe a greater training frequency could overcome some genetic limitations. Or possibly not.
The point is, more is not necessarily better. Those who want maximum muscle gains may have to experiment to see what works best. Those who want to gain strength and function and better health might be satisfied with once weekly weight training.
Added: For good cardiovascular fitness, you probably need to exercise more than once a week. I don’t want to imply that you don’t. The above considerations apply to strength and muscle growth.