MS Muscle Weakness: What It Feels Like and What Can Help

If you have multiple sclerosis (MS), your limbs may feel harder to lift, climbing stairs can be difficult, and running for exercise may no longer be a viable workout. That’s because this autoimmune condition often leads to muscle weakness, affecting somewhere between 40% and 80% of people diagnosed with MS, according to MS Society UK.

But you don’t have to simply accept a steady decline of your mobility and stamina from multiple sclerosis-related muscle weakness. There are strategies you can adopt to help combat it, starting with the right reconditioning moves, targeted physical therapy, and assistive devices for MS.

What Causes Muscle Weakness in Multiple Sclerosis?

Muscle weakness from MS occurs in two distinct ways. The first, called primary muscle weakness, is the direct result of the disease process itself. The second, called secondary muscle weakness, develops due to the progressive deconditioning of your muscles from reduced activity after primary MS symptoms appear, linger, and sometimes worsen over time.

Muscle weakness from MS can occur in any part of your body, per the National MS Society, affecting one limb, one side, both legs, and/or multiple muscle groups. Once such symptoms set in, you might notice your endurance dipping during your regular daily activities, or you may even trip and fall frequently, robbing you of your independence.

Primary Muscle Weakness

Your brain and spinal cord make up your central nervous system (CNS), which sends signals along a long pathway, called the corticospinal tract, to your muscles to control the “conscious, voluntary movement of your limbs,” says Daniel Gratch, M.D., a neuroimmunologist at Northwell Health’s Lenox Hill Hospital in New York City.

Although the exact cause is unknown, MS attacks the protective coating, called myelin, that surrounds the nerve fibers in your CNS, Dr. Gratch explains, leaving them damaged or stripped, much like a frayed electrical wire. When demyelination occurs, normal impulses being sent from the CNS are disrupted, leading to a wide range of possible symptoms, including muscle weakness. “The corticospinal tract is so prominent throughout the CNS, you’re likely to get demyelination there,” he notes, explaining that this is the reason why muscle weakness is so common in people with multiple sclerosis.

Secondary Muscle Weakness

Once CNS signals go awry in people with multiple sclerosis, it leads to both muscle stiffness and weakness. Over time, stiffness, fatigue, and balance problems make it tougher to keep doing your regular activities; as a result, your muscles become weaker still. This is what drives the deconditioning found in secondary weakness, notes Daniel Giang, M.D., a neurologist from Loma Linda University in California.

The good news? Many people with multiple sclerosis can help battle deconditioning by staying as active as possible. Physical therapy often helps people with this condition maintain strength, posture, mobility, and endurance while addressing other problems that may make movement harder, including pain and/or stiffness, per the National MS Society.

What Does MS Muscle Weakness Feel Like?

MS-related weakness doesn’t feel the same for everyone, says Dr. Giang. You might notice any or all of the following symptoms at different times:

• Your legs feel heavy, like they each weigh 100 pounds.
• Your legs feel noodle- or jelly-like, leaving you wobbling and unable to support yourself.
• It’s harder to lift your foot when walking and you might even drag it, causing you to trip.
• You struggle to climb stairs, rise from a chair, or lift objects.
• You feel weak on one side of the body.
• Both of your legs or several muscle groups are affected.

There isn’t one characteristic or sensation that defines MS-related weakness, which can occur alongside balance problems and/or numbness. Each symptom may require a different approach to treat, Dr. Giang points out.

You may also find that moving is tougher after you’ve been active for a while or as the day goes on, according to Dr. Gratch. If you notice new weakness, more frequent stumbling, or a change in what you can do comfortably and safely, tell your provider.

MS Muscle Weakness vs. Fatigue: What’s the Difference?

Muscle weakness and fatigue often go hand in hand in multiple sclerosis, according to MS Trust. But they are not the same thing, says Dr. Giang. Muscle weakness means you have reduced strength or difficulty producing the force needed to move a body part. Fatigue, on the other hand, is an overwhelming sense of physical or mental exhaustion that can make everyday activities feel harder to do, even when your muscles are still capable of generating normal force.

“Baseline weakness or imbalance is due to lack of electrical signals to the muscles, not because the muscles themselves are weak,” Dr. Giang explains. Fatigue may then worsen your ability to move.

Heat sensitivity, Dr. Gratch says, can make both symptoms more noticeable. When your body temperature rises, damaged nerve pathways may transmit signals less efficiently, temporarily worsening weakness or fatigue. Once you cool down, your symptoms should improve. If they don’t, let your doctor know, he advises.

How MS Leg Weakness Affects Walking

Walking requires more than just muscle strength—it relies on something called proprioception, or the body’s ability to sense its own position and movements in space, per the Cleveland Clinic. Multiple sclerosis can disrupt the functions that help you do this, making walking slower, less steady, or more tiring. MS-related stiffness, numbness, balance problems, and fatigue pile on to these difficulties.

Weakness in your legs may make it difficult to lift your feet, climb stairs, or stand up from a seated position. Some people develop a condition known as foot drop, which occurs when the front of the foot doesn’t lift properly during a step. Your toes may drag or catch on the ground, upping your risk of tripping and falling. According to MS Trust, this symptom can be successfully treated with functional electrical stimulation, which applies small electrical charges to affected muscles to help restore function.

Dr. Giang describes such sensory and balance problems as being a “sensation that’s like walking in a carnival fun house.” He explains that the CNS signaling coming to your legs may not match what your eyes are telling you about your surroundings. If walking becomes more difficult, a physical therapist can assess your strength, balance, gait, and need for mobility support. The right interventions may help you remain as active and independent as possible.

Why Does Multiple Sclerosis Weakness Come and Go?

MS-related weakness can fluctuate throughout the day, research shows. It may also improve after a relapse or become more persistent over time. During a relapse (also referred to as an MS flare-up), new inflammation and damage in the CNS can cause new weakness or worsen existing symptoms. Some people recover fully, while others have residual weakness that remains after the relapse subsides, Dr. Gratch notes.

Weakness can sometimes temporarily worsen without a new relapse, he adds. Heat, fever, illness, and overexertion may interfere with the transmission of signals along nerve pathways already damaged by MS. Sometimes called a pseudo-relapse, this type of temporary worsening of symptoms usually resolves after you cool down or recover from an infection.

In some people with rarer types of MS, muscle weakness gradually worsens as the disease progresses, even without distinct relapses, according to the Cleveland Clinic. Deconditioning, joint problems, and other health issues may also contribute.

How Is MS Muscle Weakness Evaluated?

If you’ve been struggling with MS-related muscle weakness, your MS care team will likely ask you when your symptoms started, which parts of your body are affected, whether or not the symptoms fluctuate, and how they are interfering with daily activities. A neurological exam can assess muscle strength, tone, reflexes, sensation, coordination, and balance. Your doctor may also observe how you walk and grade your level of strength on a scale of 1 to 5, with a score of 5 meaning full strength, according to the Merck Manual.

Dr. Giang says he often asks patients to perform the same movement several times. Someone with multiple sclerosis may initially demonstrate normal strength when lifting a knee against resistance, but then become weaker after repeating the movement.

Physical Therapy and Exercise for Multiple Sclerosis Muscle Weakness

A customized physical therapy program to combat muscle weakness can help you maintain strength, flexibility, balance, and endurance while reducing the risk of injury, says Dr. Giang, who emphasizes the importance of finding a therapist experienced in neurological conditions. Neuro physical therapists are trained to understand how MS can affect movement, fatigue, balance, and muscle control, and can tailor exercises to your needs.

According to Mass General Brigham, a physical therapy program for MS muscle weakness can include:

• Aerobic activity. Brisk walking on even surfaces can help boost energy, as can pedaling on a stationary bike.
• Balance and agility training. These can include simple moves like balancing on one foot without any hand support, or trying the same thing on a slightly uneven surface to improve stability.
• Resistance training. Strengthening muscle groups weakened by multiple sclerosis may also help improve symptoms of spasticity.
• Stretching. This can be especially important for those with stiff, tight muscles.

With your MS care team’s approval, start exercising at a manageable level, increase activity gradually, and allow time for recovery. Try exercising in a cool environment or at a cooler time of day to avoid overheating, Dr. Giang advises. Many of his patients exercise early in the morning when their core body temperature is at its lowest.

Mobility Aids for Multiple Sclerosis Leg Weakness

Mobility aids can help make walking safer, conserve energy, and enable you to participate in activities that might otherwise be difficult or even impossible to do. Remember, using one isn’t a sign of giving up; it’s a way to match the support you need in the moment to the task at hand. Your MS care team can help you choose the best device for your specific needs.

If you’re experiencing muscle weakness from multiple sclerosis, you may benefit from one or more of the following, per the National MS Society:

• Cane. A cane provides light support when weakness or balance problems affect one side more than the other.
• Crutches. Some people with MS prefer forearm crutches for greater stability, according to the site Crutch Reviews.
• Rollator. A rollator is a wheeled walker, usually equipped with hand brakes and a seat. It provides walking support that allows you to stop and sit when fatigue or weakness strikes.
• Scooter. A motorized scooter may help you save energy during longer outings, especially if you can walk short distances with balance and control but may need an assistive device to avoid overexertion.
• Walker. A walker offers more support than a cane and can help if you need greater stability or assistance bearing weight while walking.
• Wheelchair. A power wheelchair may help when weakness, balance problems, or fatigue make walking unsafe or impractical for some or all activities.

Everyday Strategies for Managing MS Weakness

Dr. Gratch emphasizes that a self-care routine for multiple sclerosis works best as part of a broader approach to symptom management, alongside—not instead of—appropriate medical treatment.

These strategies can help manage MS-related muscle weakness:

• Break demanding tasks into smaller steps. Also, alternate activity with rest, and plan important outings for the time of day when you feel strongest. Pace yourself to conserve your energy reserves.
• Carefully adhere to your care plan. Muscle weakness can be compounded by pain, stiffness, poor sleep, and fatigue. Follow your prescribed medications and customized therapies to help manage your specific MS symptoms.
• Create an MS-friendly environment. Remove all trip hazards in both your living and workspaces, including loose rugs and clutter. Keep everyday items within easy reach. And consider installing grab bars or other home modifications if needed.
• Keep cool. If heat worsens your muscle weakness, remain inside in air-conditioned spaces, and avoid overheating during exercise or daily activities.
• Take care of yourself. Move your body frequently, always prioritize sleep, and eat a balanced diet.
• Use prescribed mobility aids consistently. Save energy and make moving safer and more efficient with the help of assistive devices when needed.

When to Contact a Doctor About Muscle Weakness

Both experts advise that you contact your MS care team if:

• You develop new weakness.
• Existing weakness becomes noticeably worse.
• Your symptoms interfere with walking, balance, or everyday activities.

The National MS Society recommends you seek urgent medical attention for:

• MS relapse and new symptoms.
• Unexplained side effects of your medications.
• Infection.
• Falls.
• Any symptom that could indicate a medical emergency, such as a heart attack or stroke.

Remember, if your symptoms are severe or affecting your safety, don’t wait for them to last 24 hours before seeking medical advice. Your MS care team can help determine whether your symptoms indicate temporary worsening related to heat or infection, a relapse, or some other cause.