Q. When I extend my arms, called shoulder extension in yoga, with a strap looped around my hands (or just hands clasped), I have significantly more range of motion than when I do the same action but holding a block. What is the difference?
These are the kinds of questions that I ponder at 3:30 am, when I should be sleeping. I don’t have enough tacit knowledge (yet) to answer such questions, so I get out my anatomy books and play, trying to puzzle it out. It is in this way that I’ve layered functional, contextual understanding on top of fuzzy recollections and ineffectual memorization. As always, what is happening is way more complex than my summation, but you’ll get the drift.
What are the similarities?
Let’s first look at the similarities. In both examples of shoulder extension, the primary movers or agonists – being the posterior deltoids and triceps – are contracting with help from latissimus dorsi aka lats, while the anterior deltoids, pectoralis major aka pecs and biceps are stretching.
And now the differences.
In the strap example, because my hands have to push outward against the strap to keep it taut, my arms are therefore attempting to abduct or move away from my body, which means my lateral deltoids are also contracting. Were the strap removed, continuing to abduct my arms would eventually bring them into the arm position of Virabhadrasana 2. The loads are different, but the result would look about the same if I were clasping my hands instead of using a strap.
In the block example, because my hands have to push into the block to keep if from falling to the floor, my arms are thus adducting or moving towards my body, meaning my lats and pecs are also contracting. By contracting my chest muscles, I effectively put the break on further extension of my arms behind me because I am now co-contracting muscles that both cause and keep me from extending. And that is why I cannot lift my arms as high with the block.
Which method is better?
Is one method – strap or block – better than the other? It depends…
If you want to increase strength and integrity of your tendons, which is my goal in yoga, the bock technique is better for two reasons:
Co-contracting provides greater resistance for the primary movers – posterior deltoids and triceps. I don’t need to tell you this as you can experience it yourself, when you attempt to extend further.
- the technique I use is to place a block behind me with elbows extended (straight), press firmly into the block (~75% of maximum effort) and try to lift it higher – just like in the picture above.
Adding an isometric contraction at end range of motion signals collagen production in your tendons thus increasing their stiffness and their capacity to withstand greater loads. Relax already, stiffness as a biomechanical concept is not the same as that feeling of “tight” or “stiff” often exclaimed in yoga; tendon stiffness is a desirable thing. This kind of muscular work in yoga will make your tendons and ligaments more resilient against injury and ultimately may improve your flexibility.
- One technique I use is to place a block behind me with elbows extended, and barely holding the block, lift my arms until I hit my end range and then press my hands firmly (~75% of maximum effort) into the block, holding for 10 seconds. This technique differs from what I described previously in that I lift my arms first and press the block second; whereas previously, I pressed first and lifted second. It makes a difference how you get there.
- Another technique would be to press the block down onto a counter/table which is essentially trying to move into shoulder flexion and will fire the stretching anterior deltoid. At the same time, press your hands into the block (adduct) to isometrically contract your pectoralis major. It’s a lot of work!
- And yet another technique would be to clasp your hands and push them into a block positioned against your sacrum – here you get concentric work in the posterior deltoids, triceps, and lats as well as isometric contraction in your anterior deltoids while they are stretching at what may or may not be your end range. It doesn’t matter – you want to be be able to generate force at all ranges of motion.
Think of this work in shoulder extension as prep work for puvottonasana aka reverse table top/plank. Ray Long, whom I introduce in an earlier post, is a master at knowing what muscles are working in just about any yoga pose you can think of. Once you know which muscles are contracting and which are stretching in a pose, you can manipulate variables to increase active mobility. He cues to isometrically attempt to scrub or drag the hands towards the hips, but without actually moving them. This simulates shoulder flexion, and just like in the examples above using the table or the block against the sacrum, it causes an isometric contraction in the muscles that are stretching, and that makes them strong, more resilient at that range of motion. You can read more here in his book Yoga Mat Companion 3: Anatomy for Backbends and Twists.
Or, you could just go back to passively flopping your arms overhead, which may increase your flexibility, but won’t increase strength and resiliency of your tissues. I like to think of passive, yummy poses as junk food yoga, a nod to Katy Bowman’s junk food walking. It’s really yummy and pleasurable, but should only be consumed in small amounts, not that often, and never in place of nutritious, connective tissue loving active mobility.