Effects of exercise training on multiple sclerosis biomarkers of central nervous system and disease status: a systematic review of intervention studies.

BACKGROUND AND PURPOSE: Multiple sclerosis (MS) is a demyelinating and neurodegenerative disease of the central nervous system (CNS) that can be tracked through biomarkers of disease status. We investigated the effects of exercise on MS biomarkers associated with CNS status including imaging, blood-brain barrier (BBB) function and neurotrophic factors. METHODS: We conducted open-dated searches of Scopus, Medline, EMBASE and the Cochrane Library. We included studies written in English describing interventions of exercise that measured one or more of the biomarkers associated with MS published up to October 2018. RESULTS: We located a total of 3012 citations through searches in electronic databases. Of these, 16 studies were eligible for review; six studies focused on magnetic resonance imaging (MRI) markers, nine studies focused on neurotrophic factors and three studies focused on BBB function markers. It is of note that two studies included both neurotrophic factor and BBB function markers and are therefore included across categories of biomarkers in this review. The existing evidence from MRI studies confirmed that exercise training can improve CNS integrity and function. There is evidence of a positive effect of exercise training on modulation of BBB permeability markers and brain-derived neurotrophic factor. CONCLUSIONS: Exercise successfully improves MRI outcomes and peripheral biomarkers (i.e. brain-derived neurotrophic factor) in people with MS. This suggests that exercise can be recommended as an adjuvant therapy for MS treatment. This conclusion is tempered by some methodological limitations including small sample sizes and high drop-out rates in the reviewed studies.

The effect of resistance training on quadriceps muscle volume and some growth factors in elderly and young men.

Aging process is associated with loss of muscle mass, strength and growth factors dysfunction. Resistance training is one of the effective methods to overcome a decline in muscle mass, strength and also can modulate the level of myostatin, follistatin and insulin-like growth factor-1 (IGF-1) factors. The purpose of this study was to investigate the effect of 8 week resistance training on different anabolic factors which influence muscle hypertrophy in elderly and young men. Fifteen elderly and sixteen young men volunteered and participated in a periodized 3-day per week progressive resistance training program for a total of 8 weeks. Daily calorie intake, muscle volume, cross-sectional area (by computed tomography) and myostatin, follistatin, IGF-1, growth hormone (GH) and testosterone were calculated before and after the training protocol. At the end of the training period, the strength in the elderly group increased significantly compared to the young group (p<0,05); no differences of daily nutrient intake were found in both groups (p>0,05). Quadriceps muscle volume and cross-sectional area increased more in the younger group (p<0,05). Myostatin concentration significantly decreased in both groups (p<0,05), yet the amount of change was not different in either groups (p>0,05). Follistatin and testosterone increased in both groups (p<0,05), but growth hormone and IGF-1 increased in the younger group only (p<0,05). Resistance training improved hypertrophy and lead to anabolic conditions in elder and young subjects, but in different ways. In this regard, GH-IGF-1 axis and growth factors profile at the baseline had an important role in different age-related hypertrophy.