High-Intensity Interval Training (HIIT) for Fatigue Management in Multiple Sclerosis

For years, the prevailing wisdom for our patients with Multiple Sclerosis has been to conserve energy to combat the pervasive fatigue that so often accompanies the condition. We've advised them to pace themselves, to avoid overexertion, and to listen to their bodies. But what if we've been missing a key piece of the puzzle? What if, instead of simply resting more, our patients could benefit from exercising smarter and, dare we say, harder? This is the provocative question at the center of a growing body of research into the use of High-Intensity Interval Training (HIIT) for managing MS-related fatigue. We've all witnessed the explosion of HIIT in the mainstream fitness world, but its application in a clinical population like MS rightly gives us pause. Is it safe? Is it feasible? And most importantly, is it effective? The evidence is increasingly pointing to a resounding 'yes.' Research is demonstrating that not only is HIIT a safe option for many people with MS, but it can be just as effective—and in some cases, more so—than the standard recommendation of moderate continuous training (MCT) for improving fatigue, walking speed, and overall quality of life. ### Diving into the Evidence A landmark 2024 systematic review and meta-analysis by Youssef et al., published in the prestigious *Archives of Physical Medicine and Rehabilitation*, directly compared HIIT and MCT. Their findings were nuanced and insightful. While HIIT was not found to be definitively superior to MCT in reducing fatigue, it did demonstrate greater improvements in two critical areas: cardiorespiratory fitness (VO2max) and memory. This suggests that while both forms of exercise can help with the subjective feeling of fatigue, HIIT may offer a more significant physiological and cognitive benefit. This was further corroborated by a 2025 meta-analysis from Martín-Núñez et al. in the *American Journal of Physical Medicine & Rehabilitation*, which concluded that HIIT significantly improved both exercise capacity and fatigue in individuals with MS. So, what does a HIIT protocol for an individual with MS actually entail? The literature presents some variability, but a consistent principle is the use of short, intense bursts of exercise followed by longer periods of active recovery. A practical starting point, as outlined in a guide from ActiveMSers, is a work-to-rest ratio of 1:4 to 1:6. This could translate to 30 seconds of maximal effort on a piece of cardio equipment, followed by a full 2 minutes of gentle, active recovery. The intensity during the 'work' interval is key; it should be high, corresponding to an 8 or 9 on a 10-point scale of perceived exertion (RPE). The goal is to push the cardiovascular system to its limits, but only for a very brief, manageable period. ### From Research to Reality: Clinical Application Translating this research into a concrete plan for our patients requires careful consideration and a personalized approach. The first step is appropriate patient selection. HIIT is not a one-size-fits-all solution. Patients with significant cardiovascular comorbidities, severe deconditioning, or a high level of disability may need to begin with a more traditional, less intense exercise regimen. However, for a large subset of our patients, particularly those with mild to moderate disability, HIIT represents a powerful and viable therapeutic option. When initiating a HIIT program, a thorough warm-up of at least 2-3 minutes of light cardiovascular activity is essential. Following the warm-up, the interval portion of the workout can begin. Starting with 3-5 intervals is a conservative and safe approach. The 'work' interval can be performed on a variety of modalities, depending on the patient's abilities and preferences. This could include fast walking or jogging on a treadmill, 'sprinting' on a stationary bike or elliptical trainer, or even performing bodyweight exercises like modified jumping jacks or high knees. The 'rest' interval should consist of active recovery, such as slow walking or gentle pedaling, to allow the heart rate to come down gradually. The entire workout, including warm-up and cool-down, can be completed in as little as 15-20 minutes, making it an incredibly time-efficient option for patients who may be struggling with limited energy reserves. One of the most significant barriers to exercise for people with MS is heat sensitivity. The structure of HIIT, with its built-in long recovery periods, is inherently well-suited to managing this issue. We should still encourage our patients to utilize all available cooling strategies, such as using fans, wearing cooling vests, and sipping on cold water throughout the session. It is also crucial to set realistic expectations. The benefits of HIIT are not instantaneous. It may take several weeks or even a couple of months of consistent training for patients to notice a tangible improvement in their fatigue levels. ### The Final Word High-Intensity Interval Training is a paradigm-shifting tool in our arsenal for managing MS-related fatigue. It offers a safe, effective, and remarkably time-efficient method for improving not just fatigue, but also cardiorespiratory fitness and cognitive function. By embracing a thoughtful and individualized approach, we can empower our patients to harness the transformative power of HIIT, helping them to lead more active, energetic, and fulfilling lives.