High-intensity Interval Training Reduces Symptom- And Disability-associated Inflammation Marker In Persons With Multiple Sclerosis

Abstract

The inflammation marker neutrophil/lymphocyte ratio (NLR) receives increased attention in various diseases and can be influenced by acute exercise. In persons with multiple sclerosis (PwMS), the NLR is elevated and associated with disability and symptom severity. High-intensity interval training (HIIT) may induce larger benefits in PwMS than moderate continous training (MCT). PURPOSE: To explore acute and chronic effects of HIIT vs. MCT on NLR and cardiorespiratory fitness (chronic only) in PwMS. METHODS: An interims analysis of a randomized controlled trial comparing 3-weeks of HIIT vs. MCT during inpatient rehabilitation was conducted. 60 PwMS (mean age 49.7 yrs, EDSS 3-6) with relapsing remitting (n=38) and secondary progressive (n=22) subtype were included. The HIIT group performed 5×1.5 min intervals at 95–100% of their maximum heart rate (HRmax) with active breaks for 2 min in between. The MCT group exercised 24 min continuously at 65% HRmax. Both groups exercised 3×/week. An incremental exercise test with spirometry was conducted before and after the intervention. To assess chronic effects on NLR, blood samples were collected before (T0) the first exercise session and after the intervention period (T3) during resting conditions. To assess acute effects on NLR, samples were also collected immediately (T1) and 3 hours (h) (T2) after the first exercise session. NLR was calculated from blood panels. Baseline-adjusted ANCOVAs with Bonferroni post-hoc test were performed. RESULTS: Relative VO2peak increased in HIIT (mean difference (MD)=2.47 ml.kg-1.min-1, p<.001) and MCT (MD=1.5 ml.kg-1.min-1, p=.004), but no group differences were found. The increase in realtive peak power was larger in HIIT than in MCT (MD=.17 watts.kg-1, p=.031). NLR decreased after the intervention period (T3) within HIIT only (MD=-.27, p=.01). NLR was greater in HIIT 3 h after the first exercise session (T2) compared to MCT (MD=1.6, p=.05). CONCLUSION: Despite the short intervention period, cardiorepiratory fitness improved in both exercise modalities, whereas HIIT may induce greater enhancements. Only HIIT chronically reduced the NLR, thereby potentially contributing to symptom alleviation in PwMS. This chronic response might be due to repetitive inflammatory states after each HIIT session as reflected by the acute effects.