Heat and Multiple Sclerosis: Safe Ways to Stay Active

Exercise is one of the most powerful tools for people living with multiple sclerosis (MS). Regular movement can help improve strength, balance, energy, mood and overall quality of life. But when temperatures climb, working out can feel like a risk instead of a reward.

That's because heat and humidity can temporarily worsen MS symptoms. The good news? You don't have to give up exercise. You just have to know when and where to do it.

Amos Katz, M.D., a neurologist specializing in MS at the Multiple Sclerosis Center at Jersey Shore University Medical Center, explains how to keep moving when the temperature spikes without triggering a flare-up

Why Heat Makes MS Symptoms Worse

"Most people with MS note that summer heat and humidity worsen their neurological symptoms temporarily," says Dr. Katz. "This is called Uhthoff's phenomenon."

Here's why it happens: MS damages the protective coating around nerves, which slows down the signals your brain sends to the rest of your body. Heat slows those signals even more.

"Even a small increase in body temperature, less than a degree, can slow nerve conduction through areas of MS damage, making existing symptoms more noticeable," Dr. Katz explains.

Symptoms that commonly flare in the heat include:

• Fatigue and exhaustion
• Walking and balance problems
• Vision changes
• Trouble with thinking and memory
• Numbness, tingling and other sensory changes
• Weakness
• Bladder and bowel symptoms
• Pain and spasticity

Humidity adds another layer. When the air is heavy with moisture, sweat doesn't evaporate the way it should. "The body cannot cool itself through sweating with high humidity, so the temperature of your core remains elevated," says Dr. Katz. That means symptoms stay pronounced longer.

"This does not mean new MS damage or relapse, and it usually improves once the body cools down," Dr. Katz says.

Keep Moving in Cooler Temps?

Exercise is good for MS. Heat is not. So the goal is to get the movement without the temperature spike.

"For most people during summer, indoor exercise is generally the much better choice, especially if you're sensitive to heat and humidity," says Dr. Katz. "The goal is to get the benefits of exercise without raising your core temperature."

Working out indoors gives you a few clear advantages:

• Air conditioning keeps your core temperature down. Cooler air means fewer heat-triggered symptoms.
• Your workouts stay consistent. You're not canceling because of a heat advisory.
• Hydration and cooling breaks are easier. Water and a place to sit are always within reach.

Indoor exercises to try: 

• Treadmill walking
• Stationary cycling
• Elliptical
• Resistance training
• Yoga and Pilates
• Rowing machine
• Swimming

Why Swimming May Be the Best Choice

"Swimming is probably the best form of exercise for people with MS because the water dissipates heat while allowing aerobic and strength training with less stress on the joints," Dr. Katz says.

The water cools you while you move, so your core temperature stays stable. And because the water supports your body weight, you can build cardiovascular fitness and strength without straining your joints.

Heat-Smart Exercise Tips 

The bottom line: You can absolutely enjoy time outdoors, just plan ahead. Dr. Katz suggests these tips to help you stay comfortable and safe: 

• Go early or late. Exercise in the early morning or after sunset, when temperatures are cooler.
• Watch the humidity, not just the temperature. Choose lower-humidity days when your body can cool itself more effectively.
• Stay in the shade. Pick shaded paths and trails whenever possible.
• Bring cold water. Carry it with you and sip throughout your workout.
• Wear light-colored clothing. Light, breathable fabrics reflect heat instead of trapping it.
• Try cooling gear. Consider a cooling vest or a cooling neck wrap if you'll be active for more than 20 minutes.
• Stop and cool down if symptoms start. If you notice symptoms getting worse, take a break and cool off. 

Next Steps & Resources

• Meet our expert: Amos Katz, M.D.
• Make an appointment online with a neurologist near you, or call 800-822-8905.
• Learn more about multiple sclerosis treatment in New Jersey