HEALTH NEWS

Study Title:

A New Strategy for Building Muscle with Exercise

Study Abstract

Background
We aimed to determine the effect of resistance exercise intensity (% 1 repetition maximum—1RM) and volume on muscle protein synthesis, anabolic signaling, and myogenic gene expression.

Methodology/Principal Findings
Fifteen men (21±1 years; BMI = 24.1±0.8 kg/m2) performed 4 sets of unilateral leg extension exercise at different exercise loads and/or volumes: 90% of repetition maximum (1RM) until volitional failure (90FAIL), 30% 1RM work-matched to 90%FAIL (30WM), or 30% 1RM performed until volitional failure (30FAIL). Infusion of [ring-13C6] phenylalanine with biopsies was used to measure rates of mixed (MIX), myofibrillar (MYO), and sarcoplasmic (SARC) protein synthesis at rest, and 4 h and 24 h after exercise. Exercise at 30WM induced a significant increase above rest in MIX (121%) and MYO (87%) protein synthesis at 4 h post-exercise and but at 24 h in the MIX only. The increase in the rate of protein synthesis in MIX and MYO at 4 h post-exercise with 90FAIL and 30FAIL was greater than 30WM, with no difference between these conditions; however, MYO remained elevated (199%) above rest at 24 h only in 30FAIL. There was a significant increase in AktSer473 at 24h in all conditions (P = 0.023) and mTORSer2448 phosphorylation at 4 h post-exercise (P = 0.025). Phosporylation of Erk1/2Tyr202/204, p70S6KThr389, and 4E-BP1Thr37/46 increased significantly (P<0.05) only in the 30FAIL condition at 4 h post-exercise, whereas, 4E-BP1Thr37/46 phosphorylation was greater 24 h after exercise than at rest in both 90FAIL (237%) and 30FAIL (312%) conditions. Pax7 mRNA expression increased at 24 h post-exercise (P = 0.02) regardless of condition. The mRNA expression of MyoD and myogenin were consistently elevated in the 30FAIL condition.

Conclusions/Significance
These results suggest that low-load high volume resistance exercise is more effective in inducing acute muscle anabolism than high-load low volume or work matched resistance exercise modes.

From press release:

Current gym dogma holds that to build muscle size you need to lift heavy weights. However, a new study conducted at McMaster University has shown that a similar degree of muscle building can be achieved by using lighter weights. The secret is to pump iron until you reach muscle fatigue.

The findings are published in PLoS ONE.

"Rather than grunting and straining to lift heavy weights, you can grab something much lighter but you have to lift it until you can't lift it anymore," says Stuart Phillips, associate professor of kinesiology at McMaster University. "We're convinced that growing muscle means stimulating your muscle to make new muscle proteins, a process in the body that over time accumulates into bigger muscles."

Phillips praised lead author and senior Ph.D. student Nicholas Burd for masterminding the project that showed it's really not the weight that you lift but the fact that you get muscular fatigue that's the critical point in building muscle. The study used light weights that represented a percentage of what the subjects could lift. The heavier weights were set to 90% of a person's best lift and the light weights at a mere 30% of what people could lift. "It's a very light weight," says Phillips noting that the 90-80% range is usually something people can lift from 5-10 times before fatigue sets in. At 30%, Burd reported that subjects could lift that weight at least 24 times before they felt fatigue.

"We're excited to see where this new paradigm will lead," says Phillips, adding that these new data have practical significance for gym enthusiasts but more importantly for people with compromised skeletal muscle mass, such as the elderly, patients with cancer, or those who are recovering from trauma, surgery or even stroke.

Study Information

Burd et al.
Low-Load High Volume Resistance Exercise Stimulates Muscle Protein Synthesis More Than High-Load Low Volume Resistance Exercise in Young Men.
PLoS ONE
2010 August
McMaster University