Muscle quivering is the involuntary shaking you sometimes feel during challenging exercise. It happens when your muscles are working hard and your nervous system is firing rapidly to keep them going.
Like muscle soreness, quivering is often linked with a “good” workout, but it’s not the sole measure of success. Its presence means you’ve challenged your body. Its absence often means your body is adapting and you’re getting stronger.
Muscle quivering can feel different depending on the type of workout. In classes like Align, barre, or Pilates (light or bodyweight, high reps, isometric or small-range movements), quivering occurs due to time under tension and fatigue in smaller stabilizer muscles. Holding or pulsing in a small range traps blood in the muscle, limits oxygen delivery, and causes rapid metabolite buildup. Stabilizers usually shake first.
In classes like Build (progressive overload, heavier weights, larger ranges of motion), quivering comes from max force output and motor unit recruitment. Here, larger muscles fatigue first because you’re lifting close to your max strength. Your nervous system calls in high-threshold motor units to keep going, which can cause shaking toward the end of a set—especially as you approach muscular failure.
Over time, quivering tends to subside as your body adapts. Improved neuromuscular coordination, strength, endurance, proprioception, and stability all reduce shaking, which are signs of real progress.
Quivering isn’t bad, but it’s not required either. Whether you shake or not, consistent training is what drives results.
Do you have more questions? Let us know. Geeking out about how things work in the human body is my favorite thing to do.
