Multimodal agility-based exercise training (MAT) versus strength and endurance training (SET) to improve multiple sclerosis-related fatigue and fatigability during inpatient rehabilitation: a randomized controlled pilot and feasibility study [ReFEx]

Weak grip strength among persons with multiple sclerosis having minimal disability is not related to agility or integrity of the corticospinal tract

INTRODUCTION

Mobility impairment is common in multiple sclerosis (MS); however, agility has received less attention. Agility requires strength and neuromuscular coordination to elicit controlled propulsive rapid whole-body movement. Grip strength is a common method to assess whole body force production, but also reflects neuromuscular integrity and global brain health. Impaired agility may be linked to loss of neuromuscular integrity (reflected by grip strength or corticospinal excitability).

OBJECTIVES

We aimed to determine whether grip strength would be associated with agility and transcranial magnetic stimulation (TMS)-based indices of corticospinal excitability and inhibition in persons with MS having low disability. We hypothesized that low grip strength would predict impaired agility and reflect low corticospinal excitability.

METHODS

We recruited 34 persons with relapsing MS (27 females; median [range] age 45.5 [21.0-65.0] years) and mild disability (median [range] Expanded Disability Status Scale 2.0 [0-3.0]), as well as a convenience sample of age- and sex-matched apparently healthy controls. Agility was tested by measuring hop length during bipedal hopping on an instrumented walkway. Grip strength was measured using a calibrated dynamometer. Corticospinal excitability and inhibition were examined using TMS-based motor evoked potential (MEP) and corticospinal silent period (CSP) recruitment curves, respectively.

RESULTS

MS participants had significantly lower grip strength than controls independent of sex. Females with and without MS had weaker grip strength than males. There were no statistically significant sex or group differences in agility. After controlling for sex, weaker grip strength was associated with shorter hop length in controls only (r = 0.645, p < .05). Grip strength did not significantly predict agility in persons with MS, nor was grip strength predicted by corticospinal excitability or inhibition.

CONCLUSIONS

In persons with MS having low disability, grip strength (normalized to body mass) was reduced despite having intact agility and walking performance. Grip strength was not associated with corticospinal excitability or inhibition, suggesting peripheral neuromuscular function, low physical activity or fitness, or other psychosocial factors may be related to weakness. Low grip strength is a putative indicator of early neuromuscular aging in persons with MS having mild disability and normal mobility.

Experiences of fatigued persons with multiple sclerosis with multimodal agility-based exercise training and the ReFEx study protocol: a qualitative extension of a feasibility study

OBJECTIVES

(1) To explore experiences of fatigued persons with multiple sclerosis (pwMS) with a new multimodal agility-based exercise training (MAT) framework and (2) to investigate the demands of the Rehabilitation, Fatigue, and Exercise (ReFEx) study protocol, which compares high-frequency MAT and 'traditional' strength and endurance training (SET) to identify possible adaptations for a powered randomised controlled trial (RCT).

DESIGN

A qualitative interview study nested within a feasibility RCT, comparing MAT and SET.

SETTING

Neurological inpatient rehabilitation centre in Germany.

PARTICIPANTS

Twenty-two pwMS were recruited for the feasibility study. Six were selected from MAT and SET, respectively, for semistructured face-to-face interviews prior to discharge, following a purposive sampling strategy. Participants had low physical disability but were at least moderately fatigued.

INTERVENTIONS

During inpatient rehabilitation (4-6 weeks) MAT participants attended group-based and manual-based MAT sessions in the gym (5×/week, 30 min) and the pool (3×/week, 30 min). SET participants exercised individually on a cycle ergometer (5×/week, 22 min) and on strength training machines (3×/week, 30 min).

RESULTS

Three key categories emerged from the interviews: (1) facilitators regarding MAT were variety and playfulness, group setting and challenging exercises. Barriers regarding MAT were feeling overburdened, feeling pressured in the group setting and the wish to perform 'traditional' strength training (not part of MAT). (2) MAT benefits were of physical and psychological nature, with improved balance stated the most. (3) Demands described the perceived exertion during MAT and SET, reflecting that there is no accumulation of fatigue during the intervention.

CONCLUSIONS

MAT is appreciated by pwMS and includes facilitators less attainable with 'traditional' SET. Evaluation of MAT in a powered RCT is indicated, if rest breaks postsession, and screening for negative self-evaluation and social comparison are considered. Future (qualitative) research should investigate the important factors of inpatient rehabilitation contributing to fatigue reduction in pwMS.

TRIAL REGISTRATION NUMBER

DRKS00023943; German Clinical Trials Register.