Exercise Timing

Exercise Set Duration is One of the Main Drivers of Muscle Growth

Study

A recent study was carried out by researchers to find out what the role of time under tension (exercise set length) had on muscle hypertrophy (growth).  In this study 30 volunteers were split into 3 groups; a control group that didn’t exercise and 2 different exercise groups.  Each exercise group performed a different protocol.  In both groups, subjects trained for 10 weeks, 3x per week on a smith machine bench press performing 3 sets each training session with each set duration totaling 36 seconds.  The difference between the groups was that 1 group performed 6 second repetitions (6 reps per set) and the other group performed 3 seconds repetitions (12 reps per set).  Results from MRI scans showed increases in chest size for both groups ranging from 20-30% and triceps size ranging from 10-15%. Strength increases were recorded at roughly 23% however there was no statistical difference between groups in strength or hypertrophy gains.

Recommendation

Recent research suggests that training volume (sets x reps x weight) is one of the main drivers of muscle hypertrophy.  This study demonstrates that volume can not be considered alone and that time under tension needs to be taken into account.  As someone introduces a new exercise, over time, reps will begin to move at a faster pace as the movement becomes more efficient with practice.  Because of this, making sure that time under tension is increasing as reps go upl becomes important to assuring that you are achieving a desired training effect. It is important to note that the strength and hypertrophy changes observed by this study most likely have more to do with metabolic adaptations and not structural changes to the muscle cell based on the rep ranges and workload percentages used.  Therefore, time under tension becomes increasingly more important to monitor the higher the reps get.

Source

Martins-Costa et al. “Equalization of Training Protocols by Time Under Tension Determines the Magnitude of Changes in Strength and Muscular Hypertrophy.” Journal of Strength and Conditioning Research, Vol. 36, Issue 7, July 2022, pp.1770-1780, DOI: 10.1519/JSC.0000000000004004