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My muscles shake during certain poses. Is it safe to keep holding them?
Yes—to an extent. Shaking or quivering muscles during difficult yoga poses are a physiological and neurological response to working hard, and signal muscular fatigue—which is usually a good thing! Don’t shy away from a pose when your muscles start to contract and relax, but do be mindful if your alignment degrades, which can increase the risk of injury. To gauge the difference, listen to your teacher’s cues and focus on your breath. If you can’t inhale and exhale smoothly, or if you start to hold or restrict your breath, your body is saying it has had enough, and your alignment could be compromised; it’s time to move out of the pose.
Another reason muscles may shake during difficult poses is dehydration, which throws off the balance of electrolytes like sodium and potassium that carry electrical impulses and allow your muscles to contract. The result: Your muscles can’t fire correctly, and they quiver. If you’re doing a strenuous practice for longer than 6o minutes, prevent quaking muscles by adding electrolytes: Sip about 20 ounces of an electrolyte- containing beverage 2 to 3 hours before practice.
Exercise physiologist and yoga teacher, San Diego, California
See also Yoga for Athletes: Loosen Tight Hip Muscles