What Are Lengthened Partials?
Lengthened partials are a training technique in which lifters perform partial repetitions. The focus is on the part of the range of motion where the muscle is stretched, such as from the bottom to the middle of a leg press or bicep curl. This approach is heavily praised as more beneficial for muscle growth than full range of motion training.
A Deeper Look at Lengthened Partials and Their Uses
Lengthened partials have become increasingly popular recently, with Milo Wolf, a coach with a Ph.D. in sports science, being among the first to discuss their benefits and practical use. He suggests that lifters can get around 5% more growth through lengthened partials.
The idea behind lengthened partials is simple, though a bit counterintuitive:
Instead of doing the full range of motion on every repetition, trainees can focus on part of the range of motion and see better results. People have looked at lengthened partials with some healthy skepticism because prevailing wisdom suggests that full ROM is superior to anything else.
However, there could be merit to this approach because the stretch under load is incredibly beneficial for muscle growth. There is a term for it: stretch-mediated hypertrophy.
By only focusing on that part of the range of motion, trainees can create a stronger growth stimulus and see better results. The idea is to remove the less stimulative part of the range of motion.
What Benefits Do Lengthened Partials Offer?
The most notable potential benefit of lengthened partials is that they could result in more growth, with numerous papers backing the idea––for example, Pedrosa et al. (2022), Kassiano et al. (2023), and Simões et al. (2023).
That said, while stretch-mediated hypertrophy is important, it’s not the only thing at play because the concentric contraction (and, to a degree, the isometric contraction) is also necessary for a good muscle stimulus.
Going all in on lengthened partials, even if the goal is pure muscle growth, is probably not the best option.
Another potential benefit of lengthened partials is that you can use them to push beyond muscle failure relatively safely. This is because muscles are stronger eccentrically and can continue to produce some force even if you’re too exhausted to do the entire concentric portion of a lift.
For example, if you’re doing a bicep curl and reach failure, you might not have enough energy to lift the weight to the top for a peak contraction (not with proper form, anyway). But you might still be able to lift the weight halfway up with okay technique and control the negative to get a few extra reps in.
Tips for Incorporating Lengthened Partials
Lengthened partials show a lot of promise and could be better for growth. However, that doesn’t mean we should immediately replace full range of motion with partials.
Here are three tips for incorporating these into your training or that of clients:
1. Start With Isolation Movements
Lengthened partials are a skill that develops with time. So, as a coach prescribing these to a client (or someone writing training plans for yourself), start with partials on simple, familiar movements like the bicep curl.
That way, you (or your client) can get enough quality practice and get a sense of what lengthened partials are and what they feel like without being at risk.
Also, if you coach clients online, have them film some of their lengthened partial sets to see how they are doing. Our strength coaching platform has a built-in chat where clients can send training videos.
2. When Using Partials In Compound Lifts, Do So On a Machine
Applying lengthened partials to compound lifts can work, but there is an inherent risk.
So, first, start with a much lighter weight than usual to see how the movement feels with the target muscles kept in a stretched position.
Second, do compound movements on a machine when possible. For example, instead of doing free weight squats, perform them on a hack squat or Smith machine.
3. Experiment With the Range of Motion
There is no defined range of motion; anything between 50 and 75% of the full range of motion can be defined as a lengthened partial.
So, when doing these or coaching clients, experiment to see what feels more natural. For example, when doing bicep curls, you could lift the weight halfway up before going down on some sets and a bit higher on others.
4. Integrate Lengthened Partials Into Normal Sets
Instead of doing lengthened partials on all reps, you could start sets as usual and transition to lengthened partials at the end of a set, close to muscle failure.
This can be an excellent way to push the intensity to a degree and occasionally go beyond muscle failure.
FAQ
1. Are lengthened partials better for muscle growth?
Some recent research suggests that lengthened partials could lead to more growth compared to normal training. However, data is still limited, so it’s best not to replace all regular sets with lengthened partials.
2. Why do long-length partials work?
Lengthened partials work because they keep the muscles in a stretched position under load, which has been shown to provide an effective stimulus for hypertrophy.
3. Are lengthened partials harder than a full range of motion?
Despite the shorter range of motion, lengthened partials tend to be more uncomfortable because the muscles are kept in a stretched position. Trainees must also be more mindful of their range of motion each rep and keep it consistent.
