Is It A Good Sign If Your Muscles Shake During A Workout? A Trainer Weighs In

As you're lowering down into the final squat of your strength training session or completing one last roll-up during Pilates, your working muscles might begin to quiver uncontrollably.

To help you get the most out of your workout, your lifting partner or instructor may encourage you to push through those tremors. But is that a good idea?

A few things can cause your muscles to quiver, says Jill Goodtree, a NASM-certified personal trainer and Rumble Boxing instructor.

First, this may simply mean your muscles are fatigued and nearing their breaking point at the end of your workout. "When your body creates shakes, it can be your muscles saying, 'I'm tired! I need help! I'm going to recruit more muscle fibers to help me,'" she notes. 

Shaking can also occur when you're learning a new movement. If you've never performed a pullup, for instance, your first few reps may be unsteady until your body acclimates to the exercise, says Goodtree. 

More seriously, trembling muscles can also be caused by dehydration, says Goodtree. Dehydration, which occurs when you're not replacing the fluids you're losing via sweat during physical activity, can affect your attention and cognitive performance1 and also reduce the efficacy of your workout, according to the American College of Sports Medicine.

It all depends on the reason behind your trembling. "If your muscles are shaking because of fatigue (for example, you are holding a plank for 60 seconds and they shake for the last 10 seconds), that can be good," says Goodtree. "Shaking in that scenario is your muscles working harder to build strength." 

That said, you'll need to be sure to maintain good form, as a compromised technique could increase your risk of injury, she adds. "If you continue with a workout and your form is sacrificed due to shaking, stop," says Goodtree. "You're not building strength—you're risking injury."

Quivering caused by dehydration, however, isn't something you should push through. "If you're shaking due to dehydration, stop exercising, consume water or an electrolyte beverage, and seek medical help if necessary," says Goodtree. If you're feeling tired, lightheaded, dizzy, or thirsty, or you have dry skin and lips, muscle cramps, or a headache—common signs3 of dehydration—that's your cue to pause your workout and replenish any lost fluid.

Although shaking during your workouts isn't always a red flag, you shouldn't necessarily strive to quiver, either. "As a fitness professional and personal trainer, I don't think 'get my muscles to shake' is an effective goal," says Goodtree.

Resistance training—an activity that might make your body tremble—plays a key role in keeping your muscles and joints healthy, particularly as you get older. Muscle mass and strength typically begin to decline after age 35, but making strides to maintain them can help support4 your daily functioning and independence and reduce your risk of injury.

Along with lifting weights and performing body-weight exercises, you can support your muscle and joint health by engaging in other types of physical activity, such as swimming, playing tennis, or dancing, according to the National Institutes of Health. What matters most, says Goodtree, is choosing a movement practice you enjoy. 

Nutrition is equally important. Remember to stay hydrated before, during, and after your workout, suggests Goodtree.

Muscle shaking during a workout can happen when you're doing a new move, completing a challenging rep, or in need of some hydration.