Whether the goal is bulging biceps or just a bit more strength and mass, a relatively light workout several times a week beats a more intense one done just once a week.
That's the conclusion of a small Australian study in which researchers spent a month tracking muscle-building progress among 36 college students.
“We have shown that a very small amount of exercise is still effective to increase muscle strength,” as long as it's done frequently, said study author Ken Kazunori Nosaka, lead professor of exercise and sports science at Edith Cowan University in Joondalup, Australia.
“So we hope,” he added, “that this would encourage people to start a daily exercise from a small amount. It is not difficult to find a time for daily muscle-strengthening exercise.”
In a report published online recently in the Scandinavian Journal of Medicine & Science in Sports, Nosaka and his colleagues noted that the World Health Organization and the American College of Sports Medicine both recommend doing muscle-strengthening activities at least twice a week — whether at home or at the gym — in order to maintain and improve fitness and health.
“However, many people do not meet this recommendation,” Nosaka said. The main excuse: not enough time.
So the researchers decided to assess the potential of so-called “minimal exercise” among young, healthy adults.
They enlisted 24 men and 12 women for the month-long study, which focused on the impact of bicep contractions on both arm strength and size.
Before being assigned to one of three groups, none of the participants had engaged in any kind of resistance training of the arms for at least six months. Nosaka described the participants as “sedentary.”
The first group performed six muscle contractions once per week. Exercises were performed on a machine designed to measure muscle strength, with measurements taken during the so-called “eccentric” portion of each bicep contraction — meaning the time spent slowly lowering a dumbbell during a curl.
The other two groups performed 30 such contractions a week. One group did six a day for five days each week, while another performed all the lifts in a single day.
In the end, the first group saw no strength or size benefit of any kind.
Those who did all 30 lifts on a single day fared better. As a group, they achieved a roughly 6% increase in muscle size, but no boost in muscle strength.
As it turned out, six lifts a day on five days of the week was the sweet spot, the findings showed.
These volunteers gained just as much size as the single-day group — plus a 10% increase in muscle strength, the researchers found.
Because the participants were relatively inactive before the study, Nosaka said the benefits they achieved from frequent moderate exercise would likely be greater than those for people who already do a lot of resistance exercises.
He said it isn't clear precisely why less intense but more frequent workouts yielded the biggest benefits.
To gain both strength and size, he said muscles may need more consistent stimulation. "A week interval may be too long for the body," Nosaka said.
The takeaway: Exercise is probably best approached as a daily activity, rather than a one-and-done agenda, he noted.
This makes sense, according to Connie Diekman, a St. Louis sports dietician, and former president of the Academy of Nutrition and Dietetics.
“As a sports dietitian, I worked with our athletic trainers to develop training programs that provided daily muscle work to keep muscle mass strong,” she noted. “So the outcome of the study is not a surprise.”
However, because participants were young, the study does not account for “the normal muscle decline due to age,” Diekman added. That means “the result for older adults may not be as significant,” she said.
But, the larger point still stands: "The key to muscle mass development and maintenance is working a well-fueled muscle” consistently, even if the exercise itself is minimal, Diekman said.
“We do know that regular muscle work, even if it is simply walking, does maintain muscle mass, even if there is no resistance work,” she said. And though the study's focus was on arms, there's every reason to think that the “benefit of daily muscle work can be extrapolated to all muscles in the body.”
And, Diekman added, that includes one of the most important muscles of all: the heart.
The American College of Sports Medicine has more about exercise and muscle strength.
SOURCES: Ken Kazunori Nosaka, PhD, lead professor, exercise and sports science, Edith Cowan University, Joondalup, Australia; Connie Diekman, MEd, RD, sports dietitian, St. Louis, and former president, Academy of Nutrition and Dietetics; Scandinavian Journal of Medicine & Science in Sports, July 31, 2022, online