How using a full range of motion (ROM) during an exercise is more beneficial then using partial reps.

May 17th, 2017 by

I’ve written about studies showing how using a full range of motion (ROM) during an exercise is more beneficial then using partial reps. Today’s post is no different.

In a study published in the Journal of Strength and Conditioning Research, 40 young men were separated into three groups. One group served as a control. So they didn’t have to do much. The other two groups performed preacher curls. As you may have guessed, one group performed the exercise using a full ROM (0 degrees to 130 degrees) while the other performed partial reps (50 degrees to 100 degrees). See the pic for an illustration of this.

Both training groups performed preachers curls twice a week for 10 weeks. The group performing partial reps used a heavier weight than the full ROM group (about 20 lbs. more) throughout the entire 10 weeks. They also periodized their training by decreasing the reps and increasing the weight over the 10 weeks. So basically every two weeks they dropped the reps and increased the amount of weight they used. However, there was, on average, always a 20 lbs. difference between the groups.

Before and after the study, the researchers measured the muscle thickness of the subject’s arms and their one-rep max on the preacher curl. What they found was that there wasn’t a significant difference in muscle thickness. However, there was a significant difference in strength between the two groups, which favoured the full ROM group. That is, the group using a full ROM, but less weight, ended up being stronger. Therefore, once again, if you can use a full ROM then you probably should (even if that means dropping the weight to do so).

And now you know. :-)

For more information:
Pinto, RS et al. Effect of range of motion on muscle strength and thickness. J Strength Cond Res. 2012. Aug;26(8):2140-5.