High-intensity Training Improves Fitness While Being Safe for Patients with Kennedy’s Disease, Small Study Suggests

High-intensity training can improve fitness and may be performed safely by patients with spinal and bulbar muscular atrophy (SBMA), a small pilot study suggests.

According to patients, high-intensity training (HIT) did not increase their muscle fatigue and was preferred to other workouts. Although more studies are needed to understand the long-term benefits and compliance of patients to HIT, researchers recommend that the exercise be considered as part of rehabilitation therapy for SBMA.

The study, “High-intensity training in patients with spinal and bulbar muscular atrophy,” was published in the Journal of Neurology.

Exercise of low or moderate intensity does not seem to benefit patients with SBMA — a rare adult-onset form of spinal muscular atrophy (SMA) also known as Kennedy’s disease — which is characterized by muscle wasting and weakness in the arms and legs. In fact, low- and moderate-level exercise can produce muscular fatigue in these patients.

HIT is a form of cardiovascular exercise that alternates short periods of intense anaerobic exercise with less intense recovery periods. This type of workout has been shown to be time-saving and efficient for healthy individuals. HIT may also benefit SBMA patients because motor neurons — the nerve cells that control muscle activity and are damaged in SBMA — are only active for a small period of time.

To test this possibility, researchers at the University of Copenhagen and Aarhus University Hospital, in Denmark, conducted a small study to investigate if HIT is feasible and safe, and if it can improve the fitness in SBMA patients.

Patients were randomized to a supervised eight-week training, followed by optional self-training for another eight weeks, or they received no training (usual care) followed by an unsupervised, at-home eight-week training.

Training included eight minutes of warm-up followed by two five-minute cycles on a stationary bike, with three minutes of recovery in between. Each cycle was based on the 30–20–10 s concept, which consisted of low-, moderate-, and high-speed cycling for 30, 20, and 10 seconds, respectively, in five minutes.

Before training, the patients received a class and an audio file with a recorded training guide to use at home. During training, they wore a pulse-watch to record heart rate, intensity of training, and patient compliance.

Of the 10 male SBMA patients who participated, eight completed the study — half in the supervised and the other half in the unsupervised group.

Both maximal oxygen consumption (a measure of exercise capacity) and maximal workload were tested before and after the training program during an incremental exercise test — a test where participants have to perform exercise that increases in intensity over time.

Taken together, training improved both fitness and workload performance in all patients after eight weeks. This was evidenced by an 8% increase in maximal oxygen consumption and a 16% greater maximal workload, compared with the start of the study.

The training was safe, as judged by stable creatine kinase levels, a blood marker of muscle damage. Patient-rated muscle fatigue, muscle pain, and activity levels also remained the same over the training period.

Moreover, all patients preferred the high-intensity training compared with other workouts. In fact, three of the four patients who completed supervised training wished to continue the program for eight more weeks without supervision.

At the end of their entire training period (16 weeks), the participants maintained their improvements in maximal oxygen consumption and workload.

However, the training program did not change the patients’ walking capacity (as assessed by the 6-min walk test) and tended to reduce their walking distance slightly from a daily average of 3.1 to 2.4 km.

“In conclusion, HIT is well-tolerated and safe for patients with SBMA. It increases fitness and training does not decrease patient’s daily activity level, and should be considered as a rehabilitation strategy for patients affected by SBMA,” the researchers wrote.

Compared with other low- and moderate-level training modalities, HIT seems to work better to improve patients’ fitness and is favored by patients, they said.

“A likely explanation for the efficacy of HIT and inefficacy of lower intensity training in SBMA could relate to the longer period of restitution between training bouts, and the shorter period that the large motor units in SBMA need to be active vs. longer duration low-to-moderate-intensity training,” the researchers said.

Future studies should evaluate the long-term effects and compliance of high-intensity training for this patient population, they added..