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Friday, August 27, 2010

Muscle fatigue is key to building muscle mass

Until recently, it was thought that for men to build muscle mass, they had to lift extremely heavy weights. Nicholas Burd from McMaster University was lead author in a study disproving this. It’s muscle fatigue, not heavy weight lifting that leads to muscle growth. In other words, lifting a lighter weight many times was more effective at building muscle mass than lifting a heavy weight a few times.

Burd and his team put 15 men through their weight lifting paces. The men were asked to lift either 90% of their maximum ability (a typical amount for men seeking to increase muscle mass) or only 30%. For the 90% weights, the men lifted the weight until ‘failure’, when they could no longer complete the full range of motion. The 30% weights were either lifted to achieve an equal amount of work (load times repetition) as was done with the 90% weights, or was done to failure. Muscle biopsies were done 4 and 24 hours after lifting the weights. Lifting the 30% weights to failure led to the greatest increase in muscle mass.

Interestingly, the total amount of work done was significantly higher in the ‘30% to failure’ group. Apparently, the men were able to push themselves to do more repetitions and ultimately lift more total weight when each load was lighter. That makes me wonder whether the true secret to gaining muscle mass is simply to move the highest total amount of weight at each session. Starting with a lower weight per repetition lets people get to a higher total weight amount than they could achieve if they started with a heavier weight.