Chapel Hill, NC – Lambert-Eaton myasthenic syndrome (LEMS) is a rare autoimmune condition that interferes with communication between nerves and muscles, leading to weakness that most often affects the hips, thighs, and shoulders.
Because that nerve-to-muscle signaling is impaired, strength can fluctuate and fatigue can build quickly. That can make exercise inconsistent — movements may be difficult at first, improve briefly, and then become harder again if you push too far.
Even so, regular movement plays an important role in maintaining muscle strength, reducing fatigue over time, and supporting overall quality of life — in part by helping counteract muscle loss and taking advantage of the warm-up effect, when repeated activity can briefly improve strength.
The key is learning how to manage your energy so you can stay active without becoming exhausted. Working with a physical therapist who understands neuromuscular disorders such as LEMS is especially important, since exercise plans need to be tailored to your strength, endurance, and symptom pattern.
Challenges of Exercising With LEMS
One of the defining aspects of LEMS is that muscles do not respond in a steady or predictable way.
“Movements that require force, such as standing up, climbing stairs, and getting out of a chair, are often the most difficult, particularly after rest, when the muscles may feel slow to activate or unusually heavy,” says Georgette Dib, MD, a neurologist at Cleveland Clinic in Columbus.
A key strategy in managing LEMS is leveraging the warm-up effect, says Dr. Dib. “In simple terms, the nerves need a few attempts to build up a strong enough signal to the muscles. Biologically, repeated activation allows calcium to accumulate in the nerve endings, which increases the release of acetylcholine and improves muscle contraction,” she says.
This means that brief, controlled movements — such as seated marches, gentle knee extensions, and weight shifts — can help prime the muscles before a more demanding task, making that movement feel easier, says Dib.
But that same mechanism can work against you if activity continues too long: It can tip into fatigue and lead to worsening weakness rather than improvement. The goal of exercise in LEMS is to strike a balance, not build in intensity in the traditional sense.
For most people, that sweet spot between benefit and fatigue can be difficult to judge without experience, says Katie Gingras, DPT, a board-certified neurologic physical therapist at UC Health in Cincinnati. “It’s important to get guidance from a neurologist or physical therapist familiar with LEMS,” she says.
Setting Realistic Expectations
With LEMS, exercise requires a shift in expectations — away from pushing your limits and toward working within them.
Typically, people with LEMS do best when exercising at a low to moderate intensity, says Kathryn Jira, a physical therapist at Ohio State University Wexner Medical Center in Columbus.
“At that level, you should still be able to talk in full sentences without becoming short of breath. Your muscles may feel warm or mildly tired but not shaky or weak, and your symptoms should not worsen later in the day or the next day,” Jira says.
Daily fluctuations are also part of the condition, so staying flexible and not being overly attached to following a rigid routine is essential.
Weakness is often most noticeable after rest and may improve with movement, but endurance tends to decline over the course of a day, making later activities more difficult even if earlier ones felt manageable, says Dib.
If exercise sessions leave you struggling to finish your day, let your physical therapist know; you may need to scale back what you’re doing at first, says Jira.
LEMS can also affect the autonomic nervous system, which can lead to irregular heart rhythms, heart palpitations, and unexpected changes in heart rate, says Gingras.
“During exercise, heart rate normally increases to meet the body’s oxygen demands, but in people with LEMS, this response may be exaggerated or insufficient. That can make it difficult to tolerate physical activity,” she says.
People should be aware of orthostatic hypotension, which is a sudden drop in blood pressure when transitioning from lying to sitting or standing positions, says Gingras.
“This can cause significant lightheadedness, which can increase the risk of falls or fainting. Staying hydrated and moving slowly during position changes can help reduce these symptoms,” she says.
Safe Exercise Selection and Modification
For most people with LEMS, the safest approach to exercise is one that emphasizes low-impact, functional movement, says Gingras. Examples include walking on level surfaces, recumbent cycling, and swimming, she says.
“These activities help maintain muscle function and mobility without placing excessive stress on the joints or neuromuscular system,” Gingras says.
Strength training can also be beneficial, particularly when it focuses on movements that translate to everyday activities. “This type of training promotes coordinated activation of multiple muscle groups for real-world tasks like standing, climbing, and lifting,” says Gingras.
“We typically recommend starting with body-weight resistance and gradually progressing to bands or light weights as tolerated,” she says. Your physical therapist will monitor you to make sure you’re not pushing muscles to the point of exhaustion.
“In strength-training sessions, people with LEMS should avoid exercising to the point of muscle burning. That sensation indicates excessive fatigue, which can increase recovery time and potentially worsen weakness,” says Gingras.
Eccentric loading, in which the muscle lengthens under tension, needs to be approached with caution, if at all. “It can place additional strain on the muscles and lead to faster fatigue or even microdamage,” says Gingras. She recommends avoiding this type of training unless specifically guided by a physical therapist.
Balance and flexibility work can play an important role in a safe exercise routine, particularly given the risk of fatigue-related instability in LEMS. Experts recommend focusing on gentle, low-intensity movements that improve stability and control, such as stretching, range-of-motion exercises, breathing work, and simple balance activities.
These slow, controlled movements can help maintain mobility and reduce fall risk when done within a comfortable intensity range and with rest as needed, says Gingras.
During your exercise session, build in brief rest periods (one to two minutes) between sets of strengthening exercises, as well as longer rest breaks after each four- to five-minute bout of aerobic activity, she says.
When planning your weekly exercise schedule, allow at least one day between strengthening or physical therapy sessions, says Gingras. “Nonstrengthening days can be used for gentle stretching and mobility, as well as breathing exercises,” she says.
Rest intervals should be built into every session rather than treated as an afterthought.
Exercise Timing and Energy Conservation
Managing energy is one of the most important aspects of exercising with LEMS, because fatigue can affect function long after the activity ends.
With LEMS, exercise may go better at certain times of day than others. Physical therapists recommend paying attention to when you feel strongest, and planning walks, physical therapy, or other movement during that window.
“If you take amifampridine, that window may be 30 to 60 minutes after a dose, when the medication is working best,” says Gingras.
Environmental factors can play a significant part in how you feel during and after exercise. “Since heat can make symptoms worse, exercise in a cool setting and stay well hydrated,” she says.
Safety Red Flags
Even with careful planning, it’s important to recognize when exercise is no longer safe.
According to Gingras, common safety red flags during exercise include the following:
- Overwhelming fatigue
- Sharp or persistent pain
- Significant increases in weakness
- Symptoms of respiratory distress such as severe shortness of breath or wheezing
Jira adds that dizziness, faintness, chest discomfort, and feeling unable to recover after activity are also signals to stop immediately and rest.
If symptoms don’t improve with rest or if they happen repeatedly, it’s important to discuss them with your healthcare provider so your exercise plan can be adjusted safely, she says.
The Takeaway
- Exercise can help people with LEMS maintain strength, mobility, and independence, but it needs to be approached carefully.
- Low- to moderate-intensity activity with planned rest is safer and more effective than pushing to fatigue.
- Timing exercise around peak energy, including shortly after taking amifampridine, can improve performance.
- Paying attention to warning signs and stopping when symptoms worsen is essential for staying safe.
Note
This article first appeared on Everyday Health.