Why the Lower Half of Your Curl Matters Most for Bigger, Stronger Arms
Researchers find training the initial part of each rep delivers greater muscle growth near the elbow and more full-range strength.
Does it matter where in the range of motion you do your curls for building muscle? Or maybe you've hit a plateau and want to know if small tweaks can lead to bigger gains? This new study explores: Does training at the start of the movement (when your muscle is stretched) build muscle and strength better than training at the end (when your elbow is almost fully bent)?
Study Aim:
The researchers wanted to see whether training the biceps in the “initial” part of the arm curl (elbow extended; muscle stretched) leads to more muscle growth and strength than training at the “final” part (elbow flexed; muscle contracted), specifically in healthy young women.
Key Points
Participants:
19 untrained young women (average age 22.8 years), each trained both arms in different ranges of motion across 8 weeks.Protocols:
One arm trained preacher curls in the initial range (0°–68° elbow flexion; muscle lengthened); the other arm trained in the final range (68°–135°; muscle shortened), three times a week.Assessment:
Muscle size (cross-sectional area, CSA) in two regions of the biceps (midpoint and near the elbow), measured by ultrasound. Strength was tested by one-repetition maximum (1RM) curl through the full range.
Results
Muscle Growth:
Training in the initial range led to significantly more growth at the distal (near the elbow) part of the biceps than training in the final range (p=0.001, effect size 0.89).
Growth in the mid-biceps was similar between ranges.
Overall biceps growth (sum of both regions) was not statistically different between protocols.
Strength Gain:
Initial range training gave a significantly greater increase in full-range strength (1RM) than final range training (p<0.001, effect size 1.05).
