Does Range of Motion Matter When Building Strength?

Does range of motion play into building strength and muscle thickness? Brazilian researchers use the fabled preacher curl to determine whether partial or full range of motion is best.

A study was recently conducted in Brazil to compare the effects of partial range of motion versus full range of motion training on strength and muscle thickness in young men. This study included forty young men with no resistance training experience, and the methods used for this study focused only on upper body resistance training. The majority of past studies that looked at range of motion (ROM) focused on knee extensors, lumbar extensors, and horizontal shoulder flexors muscle strength gains. Consequently, the sole purpose of this study was to focus entirely on the elbow flexors.1

In order to assess elbow flexion force in each individual, a 1rep-max (1RM) test was performed on the preacher curl exercise using a full ROM. The subjects were also tested before and after the 10-week training period for muscle thickness of the elbow flexors on their right arm via ultrasound.2

The elbow flexion training was performed in a bilateral mode preacher curl exercise 2 days a week for 10 weeks, with 48 hours rest between sessions. Each participant of the study was placed in 1 of 3 groups according to their maximum elbow flexion strength. Fifteen people were placed in a group that performed full ROM preacher curls (0° to 130° of elbow flexion – 0° being full elbow extension), fifteen were placed in a group that performed partial ROM preacher curls (50° to 100°), and the third group was used as a control and consisted of ten people. The ROM for the partial movement group was controlled by two metallic bars that limited the barbell displacement during each rep. If the load became too heavy for the subjects, then they were instructed to adjust the load accordingly in order to complete the required number of reps.3

The results of the study indicated that elbow flexion 1RM significantly increased for the full and partial ROM groups, but not for the control group. The 1RM strength in the full ROM group was significantly greater than the partial group after the 10-week training period. The full and partial ROM group also experienced an increase in average elbow flexor muscle thickness.4

The data from this study suggest that muscle strength as well as muscle thickness can be improved with both full and partial ROM resistance training. However, based on the results from this particular study, full ROM training may yield greater overall strength gains.

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