Just Stretching Is Not Just Stretching: Stretching Strengthens, Too

by Nina
“I think it’s possible that we should not look at stretching so much as a way to make muscles longer, but instead view it as a way to make muscles stronger over a greater range of motion.” —James Speck

Of course we’ve all heard the cliché that yoga is “just stretching.” And anyone who has taken a few yoga classes knows better than that. Why just try holding Downward-Facing Dog pose (Adho Mukha Svanasana) for a couple of minutes. Or Side Plank (Vasithasana). Or even Warrior 1 (Virbradrasana 1).And when I thought about it for a while, I realized that many of the yoga poses I could come up with that involved stretching also had weight-bearing and strength building aspects as well, such as Triangle pose (Trikonasana) and Extended Hand to Toe pose (Utthita Hasta Padangusthasana). Think about it: even a simple stretching pose like Arms Overhead pose (Urdva Hastasana) is also strengthening your arms and upper body as raising arms above your head is resisting the pull of gravity. But the yoga asana repertoire does include many poses that are more passive stretches, such as seated hip openers, seated forward bends, supported backbends, and reclined stretching poses.

So I was very intrigued to hear from Baxter in his post Friday Q&A: How to Stretch that even our passive stretching poses (Reclined Leg Stretch (Supta Padangusthasana), for example) are strengthening. I just had to look into it further. And I found out it may very well be that the way we typically think about stretching is wrong.

In his article Stretching Is Really A Form of Strengthening, physical therapist James Speck says: "Stretching and strengthening are commonly considered two separate forms of exercise, but in many ways they could be considered the same activity:

• Similar active and passive tensile forces are present in both stretching and strengthening exercises
• The body’s response to stretching and strengthening is similar in terms of the mechanical activation of pathways that promote muscle growth
• Preliminary evidence suggests that regular stretching is able to promote muscle hypertrophy and muscular strength"

So stretching alone has been found to produce changes in muscle size and strength similar to what is commonly seen with strengthening exercise. Peck cites two studies to support this claim. In Effect of hamstring stretching on hamstring muscle performance, fifteen days of static hamstring stretching was found to result in an increase in peak isokinetic torque generated by the muscles. And in Chronic Static Stretching Improves Exercise Performance, a 10-week stretching program was found not only to have increased flexibility, but also led to significant improvements in strength, muscular endurance and performance in jumping and sprinting drills. Those in the control group saw no improvements in these areas. 

Speck proposes that stretching and strengthening muscles may actually be the same process because stretching and strengthening both:

• result in muscle hypertrophy
• stimulate the expression of growth factors
• impart similar tensile forces on muscles
• lead to increased muscular strength

When we pull on a muscle during a stretch, the muscle actively, as well as passively, resists or pulls back. So the tensile forces generated from stretching may be very similar to the mechanical stress induced with strengthening exercises. Speck says that based on these findings, “it could be argued that passive stretching is very similar to low-resistance strength training exercise.”I’m not sure exactly what to make of all this, or whether it will influence how I practice—or how I recommend others should practice—but I can say this: never, ever will you see me use the word “just” in regard to stretching again.
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