Brain derived neurotrophic factor in multiple sclerosis: effect of 24 weeks endurance and resistance training.

BACKGROUND AND PURPOSE: Brain derived neurotrophic factor (BDNF) is suggested to play a neuroprotective role in multiple sclerosis (MS). However, the BDNF response to long-term exercise in MS remains unknown. Our objective was to compare resting BDNF profiles of healthy controls (HCs) and persons with relapsing-remitting MS (RRMS) and to investigate the impact of a 24-week exercise intervention on serum BDNF release in MS. METHODS: At baseline, blood BDNF levels were assessed in MS (n = 22, mean Expanded Disability Status Scale 2.6 ± 0.2, mean age 43 ± 2 years) and HCs (n = 19, mean age 47 ± 1 year). Next, persons with MS were randomized to an exercise intervention group (EX, n = 15) or a sedentary control group (SED, n = 7) completing a 24-week randomized controlled trial. In persons with MS, muscle strength, exercise tolerance and body composition were assessed, as compliance measures, at baseline and after 24 weeks. RESULTS: At baseline, the BDNF concentration of persons with RRMS was 21% lower than HCs. Following 24 weeks of intervention, changes in BDNF concentrations differed significantly between EX and SED. In particular, within EX BDNF concentrations increased 13.9% ± 8.8%, whereas it decreased 10.5% ± 4.1% within SED. Furthermore, 24 weeks of exercise induced changes in the compliance measures between EX and SED. In addition, within EX muscle strength, exercise tolerance and lean tissue mass improved, whereas these remained stable within SED. CONCLUSION: In conclusion, BDNF concentration of persons with RRMS was lower compared to HCs and increased after 24 weeks of exercise in persons with MS, compared to the non-exercise MS control group.

Ventilatory function during exercise in multiple sclerosis and impact of training intervention: cross-sectional and randomized controlled trial.

BACKGROUND: Patients with MS (pwMS) often experience resting ventilatory anomalies. Ventilatory function during exercise and impact of long-term training intervention remains however uncertain. AIM: The aim of this study was to examine the ventilatory function during exercise and impact of a 6-month training intervention in pwMS. DESIGN: Combination of a cross-sectional (part 1) and randomized controlled trial (part 2). SETTING: University rehabilitation facility. POPULATION: Caucasian patients with MS and healthy controls. METHODS: In part 1, the ventilatory function during submaximal endurance exercise was compared between pwMS (N.=37) and healthy participants (N.=15). In part 2, pwMS were then randomly assigned to a 6-month training intervention (N.=16) or usual care (N.=11). Following training intervention, ventilatory function during exercise was re-evaluated. RESULTS: Despite comparable relative exercise testing intensities between groups in part 1, significantly elevated steady-state exercise dead space/tidal volume ratio, O2 uptake and CO2 output equivalent, end-tidal O2 pressure, ratings of perceived exertion and lowered end-tidal CO2 pressure and O2 pulse was observed in pwMS (P<0.05). The degree of ventilatory dysfunction during exercise correlated significantly with ratings of perceived exertion and blood lactate content (P<0.05). In part 2, despite an improved exercise tolerance (based on reductions in heart rate, blood lactate content and ratings of perceived exertion during exercise at similar workload) after a 6-month training intervention, ventilatory dysfunction remained present during endurance exercise (P>0.05). CONCLUSION: Patients with MS experience a ventilatory dysfunction during endurance exercise, which is related to worse exercise tolerance. This ventilatory anomaly remains present after long-term training intervention. CLINICAL REHABILITATION IMPACT: Patients with MS experience ventilatory dysfunction during exercise. This dysfunction is related to exercise tolerance and ratings of perceived exertion. Long-term exercise training did not remediate this ventilatory dysfunction. The systematic examination of the pulmonary/cardiovascular system at rest and during exercise is recommended in MS.

Is long-term exercise intervention effective to improve cardiac autonomic control during exercise in subjects with multiple sclerosis? A randomized controlled trial.

BACKGROUND: Patients with multiple sclerosis (MS) suffer from a disturbed cardiac autonomic control during exercise (based on heart rate (HR) changes during exercise), which affects exercise tolerance. Whether long-term exercise intervention improves HR changes during exercise in patients with MS remains unknown. AIM: To examine whether long-term exercise intervention improves HR changes during exercise, and correlates with improvements in exercise tolerance, in patients with MS. DESIGN: Randomized controlled trial. SETTING: University rehabilitation facility. POPULATION: Twenty-three patients with MS were randomly assigned to six months of follow-up (n=9) or six months of exercise training (n=14, 54-60 training sessions). METHODS: At baseline and after three and six months of follow-up, exercise-onset (first 20 and 60 seconds) and -offset (1-minute recovery) heart rate (HR) change was determined during a constant-load exercise test: these data reflect the (re)activation of the (para)sympathetic nervous system at initiation and/or cessation of exercise. Blood lactate, HR, oxygen uptake, expiratory volume and ratings of perceived exertion (RPE) were assessed during exercise as indicators for exercise tolerance. RESULTS: Exercise-onset and -offset HR and exercise tolerance did not change during follow-up in the control group (P>0.05). In the exercise intervention group, blood lactate content and RPE during exercise decreased significantly (group/time interaction effect P<0.05), but exercise-onset and -offset HR did not change (P>0.05). No correlations were found between changes in exercise tolerance and changes in exercise-onset and -offset HR (P>0.05). CONCLUSION: In patients with MS, long-term exercise intervention does not improve HR changes during exercise, despite improvements in exercise tolerance, indicating that cardiac autonomic control during exercise is not easily improved by exercise intervention in patients with MS. CLINICAL REHABILITATION IMPACT: This study indicates that patients with MS suffer from a disturbed cardiac autonomic control during exercise, based on heart rate changes, which is not easily remediated by exercise intervention. Because a disturbed cardiac autonomic control is related to exercise intolerance in MS, it should further be explored how to remediate this anomaly through exercise intervention or other approaches.