In people who regularly lift weights, training the elbow flexors with either a limited or full range of motion for 8 weeks leads to similar increases in muscle size, as measured at specific points...

We analyzed the available evidence and found that, in people who regularly lift weights, training the elbow flexors with either a limited or full range of motion for 8 weeks leads to similar increases in muscle size at specific points along the upper arm bone [1]. This single assertion, supported by 65.0 studies or data points and with no refuting evidence, suggests that both training styles may produce comparable muscle growth in this context. What we’ve found so far is limited to one type of measurement—muscle size at specific locations on the upper arm—and only applies to individuals already accustomed to weight training. We don’t have data on muscle strength, endurance, or how the muscles change at other points along the arm. We also don’t know if these results hold for beginners, older adults, or people training for longer or shorter periods. The evidence we’ve reviewed leans toward the idea that full and partial range of motion can lead to similar muscle growth in trained individuals over an 8-week period, but we can’t say this applies universally. It’s possible that other outcomes, like joint health or movement control, could differ even if muscle size doesn’t. For now, if you’re someone who lifts regularly and your goal is to increase the size of your biceps or forearm muscles, using either a full or partial range of motion may work similarly based on what we’ve seen. But if you’re new to training or want to improve movement quality, you might still benefit from including full range of motion exercises.