For anyone who has been paying attention, the fitness industry has always been prone to trends and fads, and this has only accelerated with the advent of rapidly consumed social media content. One of the biggest trends in the past few years has been the idea of emphasizing the stretch for muscle growth, and there now exist all kinds of workouts and protocols to maximize the stretched position of a muscle to unlock gains that could otherwise only be achieved through Ronnie Coleman’s steroid regimen. Given the hype around ‘stretch-mediated hypertrophy’, or muscle growth driven by stretch, it is somewhat ironic that the idea of stretching itself before resistance training has been dismissed for a while. But as is often the case, the strength of the opinion is not always matched by the strength of the evidence.

It is true that extreme and sustained stretching directly before strength training can reduce maximal force production, but this is dependent on the type of stretch and the exercise being trained (Wolf et al., 2023; Strey et al., 2026). For example, a sustained static hamstring stretch would probably have negligible effects on squat strength, since the hamstrings do not directly contribute to force production in the squat. While a sustained quad stretch might be expected to negatively affect subsequent squat performance, a mildly uncomfortable stretch held for 10 seconds or so is very unlikely to cause any loss in strength. Most trainees report better performance after some light dynamic stretching. For example, doing some light lunges and body-weight squats to a greater depth than might be done with the barbell would be a good example of some lower intensity dynamic stretching.

But even the idea that very uncomfortable static stretching reduces subsequent strength performance rests on shaky ground. While a very extreme stretch might temporarily reduce subsequent force production in the mid-range and shortened position of a muscle, it can actually increase force production in the lengthened position (Warneke et al., 2023). One only has to look at the stretching routines of high-level gymnasts and their incredible feats of strength and power in anatomical positions that most of us can only manage to hold for a couple of seconds in a yoga class. The reality is that sustaining the mental effort and tolerating the physical discomfort of an extreme stretch that could negatively impact subsequent strength performance is simply not going to be an issue for most casual gym goers. 

And even where this might happen, these effects tend to be relatively short-lived. If squat performance feels compromised after a lot of intense stretching, you could simply go and train hamstrings and biceps for 10 minutes before coming back to squats.

Hopefully your fears around the potential negative effects of stretching on strength have been allayed. But what about stretching and muscle growth? As we mentioned at the top of this article, emphasizing the stretch for muscle growth has become a hot topic in recent years. Unfortunately, the terminology used can sometimes lead to confusion. Let’s first discuss two related but slightly different concepts that can sometimes get lumped together: lengthened bias training and lengthened partials. 

Lengthened bias training refers to setting up an exercise so that a muscle will experience greater resistance in a more lengthened position compared to its shortened position. If we were to compare two exercises for the triceps, we could look at a kickback versus a skullcrusher. For the kickback the resistance will be greatest when the arm is fully extended and the muscle is nearing its full contraction, while there is comparatively little resistance at the bottom of the rep. In contrast, the greatest resistance challenge during the skullcrusher will be experienced at the bottom of the rep where the muscle is more lengthened. There are various exercises and exercise modifications which can be used to achieve a lengthened bias.

Lengthened partial training can incorporate lengthened bias exercises, but refers to completing partial range of motion repetitions in the more lengthened position of an exercise. Rather than completing the full range of motion in a lat pulldown, a trainee could instead emphasize really stretching the lats at the top of the rep and then finish the rep when the bar is reaching the top of the head rather than trying to bring it all the way to the chest. Another example might be performing flys on the pec deck from the bottom stretched position to about halfway. This method allows for more time and effort spent in that stretched position, which hypothetically would deliver greater mechanical tension and muscle growth.

Although there certainly seems to be a benefit to emphasizing the stretched position and biasing exercises to be more challenging in a lengthened position, you probably shouldn’t expect dramatic results from such an approach if you are already training with a full range of motion (Helms, 2025). If you are one of those unfortunate gym-goers who goes through a two-inch range of motion on the leg press, you will almost certainly get better results by increasing the amount of knee flexion you do, which also might require lowering the weight for these often ego-driven cases. Emphasizing a full range of motion for most movements while throwing a few lengthened partials onto the end of some exercises is a simple and effective strategy that doesn’t require overhauling your training program.

It is relatively simple and low-risk to continue performing lengthened partials past the point you can fully finish repetitions on many exercises: rows, cable flys, incline curls, calf raises, and overhead tricep extensions are just some examples. However, some exercises are less forgiving candidates for this kind of approach. Trying to perform lengthened partials in the bottom of a heavy back squat or bench press after you can no longer fully lock out the top of the rep might deliver a substantial amount of extra tension, but it is difficult to continue making gains if you are in the hospital. 

The final point we will cover in relation to lengthened partials is the concept of stretch-mediated hypertrophy. Although it is beyond the scope of this article to go into in detail, hypertrophy is believed to primarily occur through the addition of sarcomeres in parallel. Sarcomeres are the most basic functional and structural units of muscle fibers. Resistance training signals the growth of new sarcomeres which are added next to one another, thereby increasing the cross-sectional area of the muscle over time. The addition of sarcomeres in series refers to new sarcomeres being added end-to-end, thereby increasing the functional length of the muscle fibers. This phenomenon has been observed repeatedly in animal research, but is less well documented in humans (Warneke et al., 2023). Many of the animal studies in question utilize very extreme weighted stretching protocols that would be unethical to perform in humans, and raise serious animal welfare concerns. An example includes attaching weights equivalent to 30% of body mass to the wings of birds for several days at a time. These interventions result in robust increases in muscle cross-sectional area, and the addition of sarcomeres in series. 

While stretch-mediated hypertrophy, and the addition of sarcomeres-in-series, is a real phenomenon that is likely to occur in humans in some capacity, there can be some confusion around how the terms get applied. Both critics and proponents of lengthened bias training can make incorrect claims about whether it results in stretch-mediated hypertrophy. The reality is that most lengthened bias training as it is generally performed has little in common with the extreme protocols utilized in animal models (Warneke et al., 2026). The actual degree of stretching of muscle fibers, and duration of extreme stretch under load in most lengthened bias training methods is simply not comparable to that utilized in the animal research where stretch-mediated hypertrophy has been demonstrated. Instead, a more reasonable interpretation would be that stressing a muscle in a more lengthened position compared to a shortened position appears to be a more effective application of mechanical tension and may lead to slightly greater muscle growth over time (Helms, 2025). Whether that growth is ‘stretch-mediated’ is less relevant than whether it results in growth full stop.

Hopefully, this article has helped clear up some misunderstandings around the role of stretching and range of motion when it comes to strength and muscle growth. Training with a full range of motion is a great way to improve flexibility and function, but specific stretching routines can be a useful way to add some variety and address some tight spots that aren’t covered by some of your lifts. While a very uncomfortable and sustained stretch of a given muscle might temporarily reduce strength on a subsequent lift dependent on that muscle, this effect is short-lived and not a concern in most cases. Lengthened bias training and lengthened partials can be an effective way to add in some extra challenge and eke out some more muscle growth from your regular training, but they will not skyrocket your gains if you already have good training foundations. Whether that growth is stretch-mediated or not, harder training is usually better training. But whatever approach you take, just keep on lifting.