Source: 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; 5 (8): e12033 DOI: 10.1371/journal.pone.0012033
If you were to ask this question of someone in the bodybuilding field they would probably look at you as if you were crazy. Current doctrine states that in order to increase your muscle size you must lift heavy weights to overload the muscle to stimulate growth. However a new study that has been conducted at McMaster University shows that you can achieve muscle growth by using lighter weights. The premise of this study is that if you pump iron until you reach muscle fatigue you will stimulate muscle growth.
What this equates to is that you no longer have strain and grunt with heavyweights in order to stimulate your muscles to grow. However, you will have to lift them for more repetitions in order to achieve muscle fatigue. Researchers at Massey University say they are convinced that growing muscle mass means stimulating the muscle to make new muscle proteins, which is a process that over time will equate to bigger muscles. What this study shows is that what is important is not how much weight you lift but that you must take the muscle to the fatigue point in order to build muscle.
During the study researchers found that those who were able to lift heavier weights, 90% of their max, could only lift it 5 to 10 repetitions before fatigue set in. While those who lifted lighter weights, such as 30% of their max, were able to lift the weights at least 24 times before fatigue set in. For those familiar with the bodybuilding creed of heavier weights equate to bigger muscles, this is quite a contradiction. However when you look at the science behind it both methods are still achieving the same thing. The only difference is that it will take you longer to reach muscle fatigue using lighter weights than it will using the heavier weights.
For those who believe in getting in the gym and getting out quickly, using heavier weights is a faster means of achieving the muscle mass they are looking for. However the lighter weights and more repetitions method may be more beneficial for the elderly and those who are not able to lift heavy weights. This means that just about anyone can improve their muscle mass through resistance training either by using heavy weights or lighter weights by simply adjusting the amount of repetitions that they do.
It is possible to incorporate both methods of lifting into your training programme to give your muscles and joints a break from the heavy weights. For those who are physically able to lift heavy weights and who are looking for a break in their routine, the action of being able to lift lighter weights and still achieve muscle growth should be appealing.