Adolescents With MS Have Lower Levels of Physical Fitness, Study Reports

Patricia Inacio, PhD avatar

by Patricia Inacio, PhD |

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Adolescents with multiple sclerosis (MS) have lower levels of fitness compared with healthy teenagers of the same age and a sex, a study suggests.

Findings also demonstrated that among younger MS patients, higher levels of fitness were associated with lower disease activity and disability.

The study “Youth with multiple sclerosis have low levels of fitness” was published in the Multiple Sclerosis Journal.

Previous research suggested that young patients with MS who practice moderate-to-vigorous physical activity have lower disease activity and disability. Physical activity also has been linked to lower occurence of depression and fatigue.

Physical fitness, which is distinct from physical activity and is defined in the study as “a set of attributes that people have or achieve that relates to their ability to perform physical activity,” also may influence disease progression and the outcomes of young MS patients.

This parameter, however, “has not been fully studied in youth with MS or in comparison with healthy controls,” the researchers wrote.

Researchers at The Hospital for Sick Children, in Toronto, Canada, and their colleagues assessed and compared the physical fitness of 19 young MS patients, ages 11–18, to that of 21 age- and sex-matched healthy teenagers.

To that end, they compared their performance in a cardiorespiratory-fitness test, which measured maximum oxygen consumption during intense exercise (aerobic capacity), and in the two-minute walk test 2MWT, which is designed to assess walking endurance.

The cardiorespiratory-fitness test was performed on an electronically-braked cycle ergometer under the supervision of a certified exercise physiologist. After a three-minute warmup, the exercise included increased workload  adjusted to participants’ height. Upon completion, the physiologist analyzed the validity of the exercise test based on four criteria. Failure to meet two of the four criteria meant the test was excluded from the analysis.

Statistical analyses were used to explore possible links between physical fitness, the level of physical activity, fatigue, depression, and disease activity in healthy participants and in those with MS. They also compared the two groups for musculoskeletal strength, which was assessed by a handgrip strength test.

Participants’ fatigue was evaluated by the Pediatric Multidimensional Fatigue Scale, scored from zero to 100, in which higher scores meant less fatigue. Depression was evaluated by the Center for Epidemiological Studies Depression Scale Children’s Rating Scale and MS disability by the Expanded disability status scale, a method of quantifying MS in which higher scores indicate greater disability. Physical activity was measured using an accelerometer and the Godin Leisure Time Exercise Questionnaire.

Analyses showed that maximum oxygen consumption during intense exercise was lower in young MS patients compared with age- and sex-matched healthy participants — 24.7 mL/kg/min (milliliters per kilogram of body weight per minute) vs. 35.2 mL/kg/min).

MS patients also had a worst performance in the 2MWT, covering only 644 feet in two minutes, while healthy participants were able to cover 670 feet in two minutes. However, no differences were seen for grip strength between the two groups.

Researchers also found the mean body mass index (BMI) — a measure of body fat — was higher in MS patients than healthy controls (28.2 vs. 20.8 kg/m2).

Statistical analyses also showed that among young patients with MS, those with lower disease activity tended to have higher levels of cardio-respiratory fitness. MS patients with more disabilities, as shown by higher EDSS scores, tended to have lower muscle strength, while those with lower disability had higher cardiorespiratory fitness.

MS patients with lower fatigue scores also tended to have a higher cardiorespiratory fitness.

Overall, these findings suggest that “youth with MS are physically unfit, and fitness level should be explored to better understand its relationship with disease activity and disability,” they wrote.

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