Stimulating Muscle Growth

Stimulating Muscle Growth

A leg extension machine used to work the muscles of the lower body. Source: George Stepanek.

A leg extension machine used to work the muscles of the lower body. Source: George Stepanek.
Researchers at McMaster University in Hamilton, Ontario, Canada have determined that muscle fatigue and not the amount of weight involved is the critical factor in stimulating muscle growth. The new study shows that high repetitions of lower weights yields higher levels of new muscle proteins than lifting more weight fewer times. The scientists believe that these proteins lead to increased muscle mass over time, the goal of most weightlifters.

The research team, led by Ph.D. student Nicholas Burd, observed a group of fifteen healthy men aged 20-22 during a series of directed lower body exercises. Prior to the study, each man’s maximum safe lifting weight was determined and used as a baseline. During the study, each man was tested under two of the following conditions: 90% of their maximum weight for their maximum number of repetitions at that weight, 30% of their maximum weight for a number of repetitions yielding the same total weight as they could manage at 90% of their maximum weight, and 30% of their maximum weight for their maximum number of repetitions at that weight.

Muscle protein levels were measured at four hours after each exercise session and was elevated above rest levels regardless of the conditions of that session. However, the levels were higher when the subject lifted weights until they couldn’t anymore (as opposed to the case where they lifted 30% to the maximum 90% total load). Subjects were tested again 24 hours after each exercise period. At that point, the protein levels were back to the resting results for all cases except after sessions at 30% of maximum weight for the maximum number of repetitions.

While these results should help bodybuilders and athletes achieve the muscle mass they desire, the lower weight requirements mean that those who are elderly, overweight, or otherwise not in peak physical condition can still benefit from a weightlifting regime incorporating whatever amount of weight they can physically handle.

TFOT has previously reported on other exercise-related research and technology including a pill designed to replace exercise, a raft that converts energy generated by onboard exercisers into power, the Poweriser spring machine that helps users increase their range of motion and height while jumping, and the Nike + Sportband designed to collect and analyze wearer data during a variety of exercises.

Read more about the new muscle growth study in this McMaster University press release or read the paper published in the Public Library of Science.

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About the author

Janice Karin

Janice Karin has a B.A in physics from the University of Chicago and a M.S. in physics from the University of Pennsylvania. In addition to extensive experience as a technical writer focused on development tools, databases, and APIs, Janice has worked as a freelance reporter, editor, and reviewer with contributions to a variety of technology websites. One of her primary focuses has been on PDAs and mobile devices, but she is interested in many other areas of science and technology.

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