Should you be skipping the lockout on your RDLs?

Take-aways

• Skipping the lock-out on RDLs or a multi-hip will likely give you more growth.

  • Try stopping your RDLs as soon as you pass knee height - or perform half-reps.

• Strongly consider lengthened partials as your ROM of choice if you seek to maximise muscle growth.

  • Try half-reps for most of your exercises. Gradually transition over a period of 4-8 weeks.

I’d like to discuss a recently presented abstract by Maeo et al. That’s right - this has not been published yet. Since it’s unpublished and thus missing detail and potentially some “sh*t-testing” through peer-review, take these findings with a grain of salt. Nevertheless, I think they’re worth discussing.

This represents the fifth study comparing full ROM to lengthened partials (partial repetitions in the lengthened part of the exercise). Here’s what was done.

Participants performed the multi-hip extension machine exercise (shown below) with either a full ROM (90 degrees of hip flexion - until the hips were fully extended) or a lengthened partial ROM (90 degrees of hip flexion - 45 degrees of hip flexion). Training was identical for both groups, save for the difference in ROM. Specifically, participants performed 5 sets of 10 reps at 70% of 1RM (partial ROM 1RM for the partials group and vice versa) twice a week for 12 weeks.

The multi-hip machine. In this study, they performed the exercise with knees nearly locked out, similarly to how you’d perform an RDL or Good Morning.

They assessed muscle growth of the gluteus maximus and hamstring muscles via MRI. They found that, as a whole, the hip extensors grew significantly more in the lengthened partials group vs the full ROM group.

More specifically, the gluteus maximus and biceps femoris’ long head grew significantly more with a partial ROM, but there were no significant differences for the semitendinosus and semimembranosus muscles. That said, the effect sizes for the latter muscle groups also leaned in favour of the partial ROM group, such that all muscles measured grew around twice as much when doing lengthened partials vs a full ROM.

Why?

This study adds to (1) the well-established body of evidence that lengthened training leads to better hypertrophy than shortened training and (2) that lengthened partials lead to more hypertrophy than full ROM.

The latter may come as a surprise to you. However, it shouldn’t. This represents the fifth study comparing lengthened partials to a full ROM. Out of these five, 4 (including the current one) show lengthened partials result in more hypertrophy than full ROM (1, 2, 3). The fifth study showed no difference between partials and full ROM (4).

The mechanisms are.. poorly understood. It may have to do with passive tension increasing, as it increases as muscle length increases. It could also have to do with differences in regional hypertrophy: we usually see similar proximal hypertrophy but greater distal hypertrophy from longer- vs shorter-muscle length training.

Regardless, this study suggests that (1) you should strongly consider including lengthened partials or substituting full ROM with lengthened partials for growth and (2) that this notion applies to the hamstrings/glutes, in all likelihood.

If you’d like to chat about this study, feel free to comment below.

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