High-Intensity Interval Training Exercises May Reverse Decline in Multiple Sclerosis

Through high-intensity interval training, multiple sclerosis (MS) patients could potentially reverse the fiber type specific decline in myogenic stem cells called satellite cells (SC).

Since SCs are essential to muscle growth, repair, and remodeling, researchers wanted to compare the SC content and muscle environment of MS patients to age-matched healthy controls. Furthermore, they wanted to evaluate the effects of a 12-week high intensity training program that combined resistance and endurance training on the SC content in MS patients.

Researchers hypothesized that type 2 fiber SC and myonuclei content was reduced in MS patients compared with healthy patients, and that the training program would be able to reverse the decline in type 2 fibers. The study included 23 MS patients and 18 age matched healthy controls (aged >18 years).

At the beginning of the study, the MS patients were assessed for knee flexor and extensor strength, maximal endurance capacity, body composition, and self-reported physical activity levels. Researchers also collected m. Vastus Lateralis muscle biopsies from both groups at baseline, and from MS patients following 12 weeks of training.

Participants were randomized to participate in 12 weeks of high intensity interval training plus resistance training (H_ITR, n = 12) or high intensity continuous endurance plus resistance training (H_CTR, n = 11), respectively.

The frozen biopsies were sectioned and researchers performed an immunohistochemical analysis for fiber type specific SCs (Pax7⁺). The myonuclei (MN), central nuclei content and fiber cross-sectional area (fCSA) were quantified using ATPase histochemistry.

At baseline, the SCs per fiber and SCs per mm² fiber area in type 1 and 2 fibers were similar between both groups. When expressed as SCs per fiber, the SC content of type 2 fibers was 119 ± 39% (p < 0.01) and 69 ± 21% (p < 0.05) lower compared with type 1 fibers, in MS patients and healthy controls, respectively.

The patients participated in 5 sessions per 2 weeks, with the sessions interspersed by at least 1 day of rest to allow for muscle recovery.

During the first 6 weeks, the group participated in high intensity cycle interval training where the exercise duration gradually increased from 5 × 1 min with a 1-minute rest interval to 5 × 2 min with a 1-minute rest interval. During the second 6 weeks, workload jumped to reach a level at 100 to 120% of the maximal workload.

In the next part of the program, patients began moderate-to-high intensity resistance training involving leg press, leg curl, leg extension, vertical traction, arm curl, and chest press exercises.

When expressed as SCs per mm² fiber area, only the MS group showed 72 ± 21% (p < 0.05) lower SC content in type 2 fibers versus type 1. There were no significant differences found between the groups in MN or central nuclei (p=0.15).

Additionally, no differences were seen in myonuclear content between fiber type 1 and 2 in either group. After training in MS patients, there was an increase in SCs per fiber associated with type 2 fibers of 165 ± 68% (p < 0.05) and per fCSA by 135 ± 63% (p < 0.05), respectively.

For the myonuclear content of type 2 fibers, researchers observed a tendency towards an increase of 35 ± 14% following training (p = 0.06); however, no changes were seen in type 1 fibers. The findings revealed that MS patients had lower SC content in type 2 fibers compared to type 1, but authors noted that the reduction was also seen in the HCs.

The study concluded that high intensity training with resistance and endurance exercise selectively increases the SC and myonuclei content in type 2 fibers in MS patients.