Why Your Muscles Shake During Workouts and How to Prevent It

You're holding a plank, lifting weights, or powering through a tough workout when suddenly your muscles start to shake. Whether it's your arms, legs, or core, this unexpected quivering can feel strange or even worrisome. But is it a sign of something serious?

The good news: muscle shaking during exercise is completely normal and happens for a few key reasons. Below, we break down why it occurs, when it’s most likely to happen, and how to minimize it.

Why Do Muscles Shake During Workouts?

Every time you move, your brain sends signals to your muscles through motor neurons, activating different types of muscle fibers. According to the American Council on Exercise (ACE), these fibers fall into three main categories:

• Slow-twitch fibers–Used for endurance activities like walking. They resist fatigue but don’t generate much power.

• Fast-twitch fibers–Used for explosive movements like sprinting or heavy lifting. They generate more force but tire quickly.

• Moderate fast-twitch fibers–A mix between the two, balancing endurance and strength.

During a workout, your body recruits muscle fibers in stages, starting with slow-twitch fibers. As you push harder, moderate and fast-twitch fibers jump in. But when your muscles become fatigued, they start switching between fibers, sometimes leading to a brief coordination breakdown this is what causes shaking.

When Are You Most Likely to Experience Muscle Shaking?

1. Pushing to Your Limits

Intense exercise especially weightlifting or isometric holds (like planks and wall sits) requires your muscles to fire on all cylinders. When too many fibers become fatigued, your body struggles to replace them efficiently, causing tremors.

For example, during a bench press, your muscles continuously recruit new fibers to keep up with the increasing weight. As some tire out faster than others, the transition isn't always smooth, leading to shakes.

2. Doing a New or Unfamiliar Exercise

If you're trying a new workout especially one involving heavy weights or complex movements your motor neurons may lack coordination at first. Over time, with practice, your body learns the movement and shaking decreases.

"With enough repetition, your motor neurons will be able to produce a smooth, controlled movement," says Glenn Gaesser, PhD, professor of exercise physiology at Arizona State University.

How to Reduce Muscle Shaking During Exercise

While muscle trembling isn’t harmful, there are ways to minimize it and improve performance.

1. Avoid Exercising to the Point of Failure

"You don’t have to push yourself until your muscles give out to get results," Dr. Gaesser says. Studies show that stopping a few reps before failure still builds strength without excessive fatigue.

2. Gradually Increase Intensity

Instead of jumping into heavy lifting or high-intensity workouts, build up slowly. A gradual increase in intensity allows your motor neurons to adapt, reducing the chances of shaky muscles.

3. Prioritize Rest and Recovery

If your muscles are already fatigued, they’re more likely to shake during exercise. Proper recovery strategies include:

• Getting enough sleep–Muscle repair happens during deep sleep.

• Hydrating properly–Dehydration can lead to muscle cramping and spasms.

• Eating enough protein and carbs–Fueling your muscles before and after workouts helps prevent early fatigue.

4. Strengthen Stabilizing Muscles

Shaking often occurs in exercises that challenge stability, like holding a plank or balancing on one leg. Strengthening core muscles and small stabilizers can improve overall muscle control and decrease tremors.

Should You Ever Be Concerned About Muscle Shaking?

In most cases, muscle tremors stop shortly after exercise and aren’t a cause for concern.

However, if shaking is accompanied by dizziness, pain, or muscle weakness that lingers long after a workout, it could indicate an underlying issue like dehydration, electrolyte imbalance, or nerve dysfunction. If symptoms persist, consider checking in with a healthcare professional.

The Bottom Line

Muscle shaking during workouts is a natural response to fatigue and motor unit coordination. It’s most common when lifting heavy, holding a position for a long time, or trying a new exercise. While it’s generally harmless, listening to your body, building strength gradually, and allowing proper recovery can help reduce muscle tremors and improve performance.

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