Generally, when you work out you expect to get bigger muscles and become strong. But, do we necessarily need to perform rep after rep in order to see the same strength gains, or can just practicing a specific exercise give us similar results? In a recent study published in Medicine & Science in Sports & Exercise, Mattocks and colleagues explore this concept of specificity.
In this study, 38 untrained participants between the ages of 18-35 performed both a knee extension and chest press exercise twice a week for 8 weeks. Participants were assigned to one of two groups, a high-volume training group that completed what we would consider a regular gym regimen of 4 sets of 8-12 RM, or a test group that performed their 1RM up to 5 times. At each training session, the participants were asked to rate their “perceived recovery” on a scale of 0-10.
To measure changes in muscle strength, size, and recruitment between the two groups, this study compared pre and post values for 1RM, muscle thickness (via ultrasound), isokinetic & isometric strength, electrical activity in the muscle (via sEMG) and muscle endurance. As you would expect, the group that performed a higher volume of exercises saw an increase in muscle thickness and muscle endurance due to the low load high rep nature of this training regimen. Unexpectedly, this study found no between group differences in isotonic or isometric muscle strength for chest press or knee extension. Of note, the group performing the 1RM saw no increase in muscle size, but did see increases in strength equal to the high volume group.
Although this study is limited due to its short nature, the concept it introduces may change the way we think about strength training. Increases in training volume and muscle size may not be the perfect recipe for strength gains. It turns out bigger may not always be better.