Partial Reps vs Full Range of Motion: Which is Better?

For years, bodybuilders who didn’t use a full range of motion were often criticized. The claim was simple: using partial reps or “half reps” lifts was thought to be nothing more than a shortcut to lifting more weight without real gains in muscle mass. Experts in the fitness world drilled the idea that a full range of motion was essential for maximizing muscle growth. However, more recent studies challenge that long-held belief half reps using lengthen eccentrics are just as useful.

A new study is catching the attention of athletes and fitness experts alike for its surprising conclusion: performing exercises with lengthened partial repetitions, commonly referred to as partial reps, can yield the same muscle growth as a full range of motion—especially when taken to muscular failure. And perhaps the most groundbreaking aspect? Unlike many previous studies, this study was conducted on trained subjects, which focused on untrained individuals. The study, titled Lengthened Partial Repetitions Elicit Similar Muscular Adaptations as a Full Range of Motion During Resistance Training in Trained Individuals, conducted by Milo Wolf and colleagues, is making headlines in the fitness world. Published in SportRχiv (2024), it challenges some established beliefs about muscle hypertrophy and resistance training1.

When it comes to muscle growth, range of motion has long been a topic of debate. Traditionally, the idea has been that full ROM exercises are superior because they involve moving the muscle through its entire length, theoretically engaging more muscle fibers and leading to better hypertrophy. For example, a full bicep curl is believed to be more beneficial than doing partial reps focused only on the lower or upper half of the movement.

However, recent studies suggest otherwise. A 2020 study comparing cable versus barbell preacher curl training revealed that full and partial ROM could produce similar hypertrophic outcomes for the biceps, indicating that exercise selection and execution technique are critical factors in achieving desired hypertrophy.2 A 2019 study demonstrated that partial ROM can be just as effective for muscle growth, particularly when focusing on the lengthened phase of the exercise, which places the muscle under greater tension.3 Another study by Kassiano et al. (2022) found that training at longer muscle lengths led to greater hypertrophy compared to shorter muscle lengths, which supports the idea that working in the stretched position can maximize gains.4