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Comparison of the effects of long-lasting static stretching and hypertrophy training on maximal strength, muscle thickness and flexibility in the plantar flexors

PainSci » bibliography » Warneke et al 2023

One article on PainSci cites Warneke 2023: Quite a Stretch

PainSci notes on Warneke 2023:

This study is my go-to citation for a fun truth: stretching can make muscles bigger and stronger! Like pumping iron, but without the pumping, or the iron.

You really have to be quite hardcore about it, though.

This trial showed that a large dosage of just stretching induced the same kinds of changes in muscle that we normally only expect to see from "lifting heavy things" (resistance training). The results certainly are physiologically intriguing. They suggest that muscle adapts in more or less the same way to almost any kind of strong stimulus — not just exhausting it with contraction. Stress a muscle, and it will grow.

Neat, if true. Perhaps not greatly surprising, but neat.

It’s not very practical information, though, because the stretching protocol they used is just bonkers: an hour per day? For six weeks? At close to maximum stretch discomfort? For one muscle?!

Sheesh. Hard pass. Even half that intensity for half as long would still be an extremely impractical way to build any muscle.

But now you know: pull on a muscle hard enough and long enough, and your body might say, “Okay, fine, we’ll upgrade that.”

Perhaps more modest dosages would work? A similar study by Panidi et al showed a the same effect with less outrageous durations — “only” 9-15 minutes per day for three months — but it was still a study of impractically and unpleasant high volume stretching. Or still less? Unlikely: a 2020 review by Nunes et al concluded that lower-intensity stretch shows no clear sign of doing the job.

original abstract Abstracts here may not perfectly match originals, for a variety of technical and practical reasons. Some abstacts are truncated for my purposes here, if they are particularly long-winded and unhelpful. I occasionally add clarifying notes. And I make some minor corrections.

Maximal strength measured via maximal voluntary contraction is known as a key factor in competitive sports performance as well as injury risk reduction and rehabilitation. Maximal strength and hypertrophy are commonly trained by performing resistance training programs. However, literature shows that long-term, long-lasting static stretching interventions can also produce significant improvements in maximal voluntary contraction. The aim of this study is to compare increases in maximal voluntary contraction, muscle thickness and flexibility after 6 weeks of stretch training and conventional hypertrophy training. Sixty-nine (69) active participants (f = 30, m = 39; age 27.4 ± 4.4 years, height 175.8 ± 2.1 cm, and weight 79.5 ± 5.9 kg) were divided into three groups: IG1 stretched the plantar flexors continuously for one hour per day, IG2 performed hypertrophy training for the plantar flexors (5 × 10-12 reps, three days per week), while CG did not undergo any intervention. Maximal voluntary contraction, muscle thickness, pennation angle and flexibility were the dependent variables. The results of a series of two-way ANOVAs show significant interaction effects (p < 0.05) for maximal voluntary contraction (ƞ2 = 0.143-0.32, p < 0.006), muscle thickness (ƞ2 = 0.11-0.14, p < 0.021), pennation angle (ƞ2 = 0.002-0.08, p = 0.077-0.625) and flexibility (ƞ2 = 0.089-0.21, p < 0.046) for both the stretch and hypertrophy training group without significant differences (p = 0.37-0.99, d = 0.03-0.4) between both intervention groups. Thus, it can be hypothesized that mechanical tension plays a crucial role in improving maximal voluntary contraction and muscle thickness irrespective whether long-lasting stretching or hypertrophy training is used. Results show that for the calf muscle, the use of long-lasting stretching interventions can be deemed an alternative to conventional resistance training if the aim is to increase maximal voluntary contraction, muscle thickness and flexibility. However, the practical application seems to be strongly limited as a weekly stretching duration of up to 7 h a week is opposed by 3 × 15 min of common resistance training.

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