You can bulk up by lifting less weight, researchers say
heavy weights - a finding by McMaster researchers that turns conventional wisdom on
The key to muscle gain, say the researchers, is working to the point of fatigue.
"We found that loads that were quite heavy and comparatively light were equally
effective at inducing muscle growth and promoting strength," said Cam Mitchell, one of
the lead authors of the study and a PhD candidate in the Department of Kinesiology.
The research, published in the Journal of Applied Physiology, challenges the widely
accepted dogma that training with heavy weights - which can be lifted only six to 12
times before fatigue - is the best avenue to muscle growth.
"Many older adults can have joint problems which would prevent them training with
heavy loads," said Mitchell. "This study shows that they have the option of training with
lighter and less intimidating loads and can still receive the benefits."
For the study, a series of experiments were conducted on healthy, young male
volunteers to measure how their leg muscles reacted to different forms of resistance
training over a period of 10 weeks.
The researchers first determined the maximum weight each subject could lift one time
in a knee extension. Each subject was assigned to a different training program for each
In all, three different programs were used in combinations that required the volunteers
to complete sets of as many repetitions as possible with their assigned loads - typically
8 to 12 times per set at the heaviest weights and 25-30 times at the lowest weights.
The three programs used in the combinations were:
- one set at 80% of the maximum load
- three sets at 80% of the maximum
- three sets at 30% of the maximum
After 10 weeks of training, three times per week, the heavy and light groups that lifted
three sets saw significant gains in muscle volume - as measured by MRI - with no
difference among the groups. Still, the group that used heavier weights for three sets
developed a bit more strength.
The group that trained for a single set showed approximately half the increase in
muscle size seen in both the heavy and light groups.
"The complexity of current resistance training guidelines may deter some people from
resistance training and therefore from receiving the associated health benefits," said
Stuart Phillips, a professor in the Department of Kinesiology and supervisor of the
study. "Our study provides evidence for a simpler paradigm, where a much broader
range of loads including quite light loads can induce muscle growth, provided it is lifted
to the point where it is difficult to maintain good form."