Plasma brain-derived neurotrophic factor (BDNF) and sphingosine-1-phosphat (S1P) are NOT the main mediators of neuroprotection induced by resistance training in persons with multiple sclerosis-A randomized controlled trial.

Resistance training (RT) has been shown to elicit neuroprotective effects in persons with multiple sclerosis (pwMS). Brain-derived neurotrophic factor (BDNF) and Sphingosine-1-phosphat (S1P) have been put forward as potent mediators of the neuroprotective effects induced by RT. However, while increases have been shown in acute and chronic circulating BDNF levels in pwMS following aerobic exercise alone or in combination with other exercise regimes, no studies have examined this in response to RT. As a novel 'proof-of-concept' approach, we therefore examined the effects of 24 weeks of RT on acute and chronic circulating BDNF and S1P levels in the same pwMS whom our group had previously observed RT-induced neuroprotective effects in (i.e. increased cortical thickness and preservation of whole brain volume). A total of n = 30 relapsing-remitting pwMS were randomized into a training group (TG: 24 weeks of progressive high intensity resistance training, 2 sessions per week; n = 16, age 44[40:51] years, EDSS score 3.0[2.0:3.5] (median[IQR]) or a control group (CG: 24 weeks of habitual lifestyle; n = 14, age 45[37:47] years, EDSS score 3.0[2.5:3.5]). Plasma levels of BDNF and S1P were assessed by ELISA kits before and after the 24-week intervention period. No within- or between group changes were observed in acute or chronic circulating levels of BDNF. A substantial proportion of the participants had S1P levels below the detection limit, yet no within- or between changes were observed in chronic S1P plasma levels in the remaining samples. Thus, the present findings do not support that circulating plasma BDNF or S1P levels are the main mediators of the neuroprotective effects previously reported in the same group of pwMS.

Acute and chronic cytokine responses to resistance exercise and training in people with multiple sclerosis.

Exercise is a well-established part of rehabilitation for people with multiple sclerosis (PwMS), and it has been hypothesized to stimulate an anti-inflammatory environment that might be disease modifying. Yet, investigations on exercise-induced immune responses are scarce and generally not paying attention to the medical treatments of the patient. At present, PwMS are routinely enrolled in immunosuppressive medication, but exercise-induced immunomodulatory effects have not been investigated under these circumstances. The objective of this study was to investigate the acute and chronic cytokines responses to resistance exercise training in medicated PwMS. Thirty-five people with relapsing-remitting multiple sclerosis (MS) treated with interferon (IFN)-ß, were randomized to a 24-week progressive resistance training (PRT) or control group. Plasma interleukin (IL)-1ß, IL-4, IL-10, IL-17F, IL-23, tumor necrosis factor-α and IFN-γ were measured before and after 24 weeks of PRT. The acute effect was evaluated following standardized single-bout resistance exercise in the untrained and the trained state. No changes were observed in resting cytokine levels after PRT. However, an indication of reduced IL-17F secretion following resistance exercise was observed in the trained compared with the untrained state. This study suggests little acute and chronic effect of PRT on cytokine levels in IFN-treated PwMS.

Differentiated mTOR but not AMPK signaling after strength vs endurance exercise in training-accustomed individuals.

The influence of adenosine mono phosphate (AMP)-activated protein kinase (AMPK) vs Akt-mammalian target of rapamycin C1 (mTORC1) protein signaling mechanisms on converting differentiated exercise into training specific adaptations is not well-established. To investigate this, human subjects were divided into endurance, strength, and non-exercise control groups. Data were obtained before and during post-exercise recovery from single-bout exercise, conducted with an exercise mode to which the exercise subjects were accustomed through 10 weeks of prior training. Blood and muscle samples were analyzed for plasma substrates and hormones and for muscle markers of AMPK and Akt-mTORC1 protein signaling. Increases in plasma glucose, insulin, growth hormone (GH), and insulin-like growth factor (IGF)-1, and in phosphorylated muscle phospho-Akt substrate (PAS) of 160 kDa, mTOR, 70 kDa ribosomal protein S6 kinase, eukaryotic initiation factor 4E, and glycogen synthase kinase 3a were observed after strength exercise. Increased phosphorylation of AMPK, histone deacetylase5 (HDAC5), cAMP response element-binding protein, and acetyl-CoA carboxylase (ACC) was observed after endurance exercise, but not differently from after strength exercise. No changes in protein phosphorylation were observed in non-exercise controls. Endurance training produced an increase in maximal oxygen uptake and a decrease in submaximal exercise heart rate, while strength training produced increases in muscle cross-sectional area and strength. No changes in basal levels of signaling proteins were observed in response to training. The results support that in training-accustomed individuals, mTORC1 signaling is preferentially activated after hypertrophy-inducing exercise, while AMPK signaling is less specific for differentiated exercise.

Multiple sclerosis and progressive resistance training: a systematic review.

Recently progressive resistance training (PRT) has been recognised as an effective tool in the rehabilitation of persons with multiple sclerosis (MS). The objective of this study was to systematically review the literature of PRT studies for persons with MS. A comprehensive literature search (PubMed, SveMed+, Embase, Cochrane, PEDro, SPORTDiscus and Bibliotek.dk) was conducted. Identified papers were rated according to the PEDro-scale. Sixteen studies were included and scored between 3 and 8 of 11 total points on the PEDro-scale, showing a general lack of blinding. Strong evidence regarding the beneficial effect of PRT on muscle strength was observed. Regarding functional capacity, balance and self-reported measures (fatigue, quality of life and mood) evidence is less strong, but the tendency is overall positive. Indications of an effect on underlying mechanisms such as muscle morphological changes, neural adaptations and cytokines also exist, but the studies investigating these aspects are few and inconclusive. PRT has a positive effect on muscle strength for persons with MS. Heterogeneous results exist regarding the effect on functional capacity and self-reported measures probably because of differences in training protocols, samples sizes, type and severity of MS. The area of underlying mechanisms deserves more attention in future research.