Q&A: Loaded Stretching For Strength And Hypertrophy

Question: Can I gain strength and size faster by performing loaded stretches between exercises?

Answer: Research on the effect of static stretching (without weight) between sets on muscular strength and hypertrophy shows mixed results. A study by Wayne Westcott that compared the results of seventy two novice trainees doing high intensity training with and without a twenty second static stretch for the muscles worked found the group that stretched had twenty percent greater strength increases over a ten week period (1). Other studies show either no difference in strength between groups training with or without inter-set stretching (2) or that inter-set stretching reduces strength gains (3). This suggests there might be some benefit to inter-set stretching, but adding loaded stretching to your workouts isn’t going to cause you to suddenly start packing on “pounds of lean muscle” while “stripping off body fat at the same time” as some people are claiming.

There are plenty of impressive studies on the effect of loaded stretch on hypertrophy in animals, but I have yet to see this duplicated in humans. A lot of the recent marketing hype for inter-set stretching under load or “cell expansion protocol” is based on a study they claim shows it causes 200% faster muscular strength and size increases, but I have been unable to find this study anywhere anywhere, and when I asked the bodybuilder selling the program where the study was published his only reply was “University of Tampa”. I asked for a specific reference, but have yet to receive a response.

Where is the research on loaded stretch, AKA “cell expansion protocol”?

The only mention of the study I could find was in an obscure bodybuilding web site interview of Jacob Wilson, PhD who said the study involved a thirty-second loaded stretch immediately following  each set of a triple drop set of heel raises on a leg press, but gave no title, no reference, and no specifics on the results. The study is not listed on Dr. Wilsons CV, either. If I am able to find and read the study I will update this article with whatever information I find. It’s possible the study is still under review, but I’m not going to hold my breath. If a study actually showed a training technique could produce such a huge increase in muscular strength and size you would expect the authors and the people selling a program based on it to provide more details on it.

If you want to experiment with regular static or loaded stretching between exercises be very cautious with the degree of stretch. Only go until you feel a moderate stretch in the target muscles. You shouldn’t feel the stretch in your joints or feel any kind of pain. If you do, you’re going too far. Be very careful with your shoulders performing loaded stretching on exercises like pullovers and chest flys, and on any exercise where the stretch is done in the position of maximum moment arm, where the lever against the muscles is the largest.

Loaded stretching  is not going to “double your muscle gains” or cause “rapid fat loss”, as some internet marketers claim, but Westcott’s research suggests some form of inter-set stretching might be worth adding to your workouts. If you want to experiment with it do so cautiously, keep accurate records of your workouts and take measurements before you start and every couple of weeks after so you can determine the effect.

Update: Since posting this article only a few days ago I’ve received several e-mails from people who injured themselves in the past doing various types of loaded stretching, usually on exercises where the stretch was done in the position of maximum moment arm like pullovers and chest flys, but also with triceps extensions and heel raises on a leg press. Regular static stretching would be a safer option, but if you decide to experiment with loaded stretching please be careful.

Update 2: In a recent conversation Anthony Roberts informed me, “Jacob’s nickname among his colleagues and in the wider scientific/professional world is “King Midas” because everything he touches turns to gold (ie everything is proven to work when he is paid to study it, or his friends have a new product or idea). He did the work on HMB-FA that nobody believes”.

It’s pretty pathetic when a “scientist” like Wilson is falsifying research for profit. This is why it pays to be skeptical.

You can read Anthony’s expose’ on Wilson and the HMB study here.

References:

1. Best Of Both Worlds: Stretching and Strengthening, by Wayne Westcott, PhD

2. Souza, Antônio Claudio, Claudio Melibeu Bentes, Belmiro Freitas de Salles, et al. Influence of Inter-Set Stretching on Strength, Flexibility and Hormonal Adaptations. Journal of Human Kinetics, 36.1 (2013): 127-135. Retrieved 14 Jun. 2014, from doi:10.2478/hukin-2013-0013

3. Borges Bastos CL, Miranda H, Vale RG, Portal Mde N, Gomes MT, Novaes Jda S, Winchester JB. Chronic effect of static stretching on strength performance and basal serum IGF-1 levels. J Strength Cond Res. 2013 Sep;27(9):2465-72. doi: 10.1519/JSC.0b013e31828054b7.