Telling yogis to “engage” or “activate” certain muscles may be doing more harm than good. Teacher and researcher Robyn Capobianco breaks down the science.
WHEN I PRACTICE YOGA IN A PUBLIC CLASS, I love the combination of a good flow and longer holds. The opportunity to explore the movement of my breath and body while experiencing stillness helps me leave class feeling great.
In a recent vinyasa flow class, the instructor called out Virabhadrasana II (Warrior Pose II) and said we were going to hold the pose. I was excitedly about to drop into my breath for the hold when the teacher then called out, “Now, contract the muscles of your back and outer hips, and engage the muscles of your inner thighs.” As if that weren’t enough to attempt at once, she added, “Then, turn on your triceps.” I was boggled. How was I supposed to contract my outer hips and engage my inner thighs and turn on my triceps? I have a PhD in neuromechanics, and I couldn’t figure it out. As a result, that inner peace I was going for turned into utter confusion, and rather than being in the pose, my inner teacher piped up (albeit silently) as I constructed cues that would better help all of us students in the room accomplish the actions our teacher was requesting.
Sadly, muscular cues like “contract,” “turn on,” or “relax” are becoming increasingly common in yoga class. But do students— even advanced practitioners—really know how to engage these muscles? When you’re told to “engage your hamstrings” in Setu Bandha Sarvangasana (Bridge Pose), for example, are you really engaging your hamstrings to the best of your ability? Or would you be able to more efficiently engage your hamstrings if the teacher told you to “isometrically drag your heels back toward your butt”? And more importantly, do cues to engage specific muscles achieve their intended goals of helping us find better alignment and ultimately feel more embodied? Scientific evidence points to no.
Research on motor learning consistently finds that instructions that have an internal focus (read: cues for muscular actions, such as “contract your hamstrings”) are much less effective at actually triggering contraction than ones that have an external focus—meaning they are directed at the actual movement that prompts a muscular action, such as “try to drag your heels toward your butt.” According to research published in Medical Education, external cues automatically generate the motor commands that will activate the muscles necessary for accomplishing the task. In fact, the study authors found that in contrast, cues for specific muscular actions actually constrain the natural motor control system in the body and interfere with normal motor planning and execution, potentially resulting in poor pose execution and muscle-activation imbalance.
It makes sense: when you’re asked to move, your brain—with the help of the visual, vestibular (relating to the inner ear and sense of balance), and proprioceptive (the ability to sense joint position and movement) systems—generates a motor command that automatically activates the muscles necessary for accomplishing the task. We don’t need to cue specific muscles for this to happen.
Of course, there are exceptions. For example, if you’re recovering after an injury or trying to correct an irregular movement pattern, it may be more helpful to cue a specific muscle. But it’s my opinion that these cues are best done in private settings, when the end goal is specific and clear and the teacher can closely observe the results. In group classes, you can’t actually see the results of internal (muscular) cues, and you may be doing more harm than good.