High-intensity interval training can be beneficial for people with MS

Eksymä Viivi¹, Paltamaa Jaana²

¹ Pohde-The Wellbeing Services County of North Ostrobothnia, Rehabilitation unit of Haapajärvi, Finland.

² Jamk University of Applied Sciences, School of Health and Social Studies, Rehabilitation Institute, Jyväskylä, Finland.

Abstract

Exercising has become an essential part of rehabilitation and management of multiple sclerosis. Intensity recommended though, has conventionally been moderate at most. Recently, also the question of suitability of more intense training modes has risen and become under research. Aim of this thesis was to find out if high-intensity interval training (HIIT) is suitable for people with MS (pwMS) by recognizing and reporting beneficial and adverse effects of HIIT among pwMS. Scoping review was conducted in four electronic databases (MEDLINE (PubMed), CINAHL Ultimate (EBSCO), Medline (EBSCO) and Cochrane Library). The review revealed several beneficial effects of HIIT for pwMS including increased cardiorespiratory fitness, improved areas of cognitive performance and decreased levels of serum biomarkers that indicate inflammation. Number of adverse effects was low but short-term symptom exacerbation, nausea and exhaustion were experienced by some pwMS. Nevertheless, it can be concluded that HIIT is safe, suitable and beneficial for at least those pwMS who have relapsing-remitting form of the disease and whose disability level is relatively low (EDSS ≤4.5).

Keywords: Multiple sclerosis, exercise methods, high-intensity interval training (HIIT), benefits, harmful effects, reviews

Introduction

Multiple sclerosis (MS) is a chronic neurological disease where neuroinflammation causes demyelination in central nervous system (CNS). MS affects about 2.8 million people worldwide and causes serious physical disability especially among young women. The disease tends to begin around the age of 30, a time of life that is commonly important for career and family planning. (Dendrou et al., 2015, p. 545; MSIF, 2020, pp. 21, 25.) The exact cause of multiple sclerosis is still unclear and pathophysiological processes behind the disease are complicated and multicellular (Dendrou et al., 2015, pp. 546, 551). Pathophysiology of the disease evolves along its course so different processes drive different phases of the disease; inflammation causes onset and relapses whereas other processes like oxidative stress lead to neurodegeneration and chronic progression of MS. (Dendrou et al., 2015, pp. 547, 551; Jakimovski et al., 2024, p. 190.)

The disease can cause wide variety of symptoms. These include cognitive impairment, sensory and motor deficits, bladder and/or bowel dysfunction and fatigue for example. (Halabchi et al., 2017, p. 2; Jakimovski et al., 2024, p. 187; MS-tauti: Käypä hoito -suositus, 2024.) Many of these symptoms impact on functioning (ICF Research Branch, 2017).

Rehabilitation and training of people with multiple sclerosis (pwMS) has conventionally been low or at most moderate in intensity. Previously, physicians recommended to avoid exercise entirely and this practice continued for years. (Halabchi et al., 2017, p. 2.) Nowadays regular exercise is recommended as essential part of clinical management of the disease (Richardson et al., 2020, pp. 1─2). Benefits of exercising for pwMS include managing symptoms, restoring functioning and enhancing quality of life and participation in activities of daily life (Motl et al., 2017, p. 854). To possibly reach these benefits, evidence suggests that pwMS should exercise at least according to general health recommendations (3x at least 30min/week). (MS-tauti: Käypä hoito -suositus, 2024). It seems that even large doses of exercise don’t exacerbate the disease (MS-tauti: Käypä hoito -suositus, 2024) and for example Dobson& Giovannoni (2019, p. 37) recommend 4-5 sessions of aerobic exercise in a week. Recently, also the question of suitability of more intense training modes, including high intensity interval training (HIIT), has risen and become under research. (This is an observation that the author has made from following the field in general.

Lack of standardized terminology, especially of classification of intensity, means that common definition for HIIT still doesn’t exist; e.g Coates et al. (2023, p. 587) define HIIT differently in performance context than in health context. Common feature is that exercise includes repeated bouts of hard work with recovery periods of lighter work or total rest in between them. Definition of American College of Sport Medicine (ACSM) (Kravitz, 2014) also shows the typical “rule”: higher the intensity, shorter the working bout, longer the rest period. Rest periods allow recovery but only partially. The intensity required is what misleads many people when talking about HIIT. Even from health perspective, HIIT has been mistakenly thought to demand very high intensity, even “all out” efforts because early reviews were based on studies that used sprint interval training interventions. (Atakan et al., 2021, pp. 1, 3─4; Coates et al., 2023, pp. 587.)

Actually, HIIT is defined to require intensity of 80-100% of peak heart rate. Endurance athletes have utilized high-intensity interval training (HIIT) as essential part of their training programs for over a century partially since it enables bigger volume of training at high intensity level than continuous training. (Coates et al., 2023, pp. 585─586.) HIIT has several benefits, equal or superior to moderate intensity continuous training. For instance, preoperative HIIT-intervention was noticed to reduce postoperative complications and associate with increased VO2max (Clifford et al., 2023, pp. 10─11). It has been reported that cardiovascular adaptations following HIIT are similar and even superior to those of endurance training.There are also indications that single weekly HIIT training can be enough to reduce the risk of cardiovascular disease.  (Milanović et al., 2015, pp. 1470, 1477, 1479.)Exercising in intervals allows beginners to reach bigger work volume with less fatigue. Key  to successful HIIT session is to choose appropriate work and recovery intervals. This principal also allows HIIT to be used in improving cardiorespiratory fitness among insufficiently active people. (Coates et al., 2023, pp. 585─587.)

The purpose of this  scoping review  is to find out if high-intensity interval training (HIIT) is suitable for people with MS (pwMS). Thus, the main objective  is to recognize and report effects of HIIT among pwMS. This  is achieved by completing next sub-objectives:

1. explore possible benefits of HIIT for pwMS
2. explore possible adverse effects of HIIT for pwMS
3. form a recommendation of what kind of HIIT is suitable for pwMS and what functioning level is required from pwMS in order to participate in it.

Methods

This study used a scoping review of research articles focusing on MS and HIIT. It was first designed and conducted as part of a Master thesis (Eksymä, 2025). Rather recently (Munn et al., 2022, 24 p. 950) provided the next formal definition to enhance understanding of scoping reviews: “Scoping reviews are a type of evidence synthesis that aims to systematically identify and map the breadth of evidence available on a particular topic, field, concept, or issue”. Scoping review methodology allows wider range of study desings to be incorporated than systematic review and also research questions can be other than related to intervention effectiveness. (Arksey & O’Malley, 2005, p. 8; Levac et al., 2010, p. 1; Munn et al., 2022, pp. 950─951.) The main research question in this study is “Is high-intensity interval training suitable for people with MS?” This is further divided into two more specific questions: “What are possible benefits of HIIT for pwMS? And “What are possible adverse effects of HIIT for pwMS?”

Inclusion criteria

For eligibility criteria, Joanna Briggs Institute (JBI) concept of PCC (participants, concept, context) was followed (Peters et al., 2022, pp. 961─962). Studies were eligible if they included adult participants with one of the three main sub-types of MS (relapsing-remitting, secondary progressive or primary progressive MS). Hence, studies involving participants with other sub-types of MS, un-diagnosed MS or non-humane subjects, were excluded. Concept of the study was high-intensity interval training so initially studies researching the effects of either aerobic or resistance-types of HIIT, were included. HIIT was simply defined as exercise consisting of altering high-intensity and lower intensity or total rest intervals. Intensity wasn’t defined more precisely as the range of different indicators is broad and the authors wanted to allow all of those. Studies were excluded if HIIT was combined with other training modality in order to ensure exploring the effects of HIIT only. Context of the study was set to be in rehabilitation because it was seen important to find out suitability of HIIT for pwMS in this context first before examining the concept in general training -context. Both in-and out-patient settings were eligible. Limits on publication time were not used. Study protocols, review articles and articles lacking free-access full text were excluded. Both experimental and quasi-experimental studies were considered, and these included randomized controlled trials, non-randomized controlled trials, before- and after studies, interrupted time-se-ries studies. Also, prospective cohort studies and case reports could be included. In the case of qualitative research, those appropriate for research objectives were eligible.

Search strategy

Search process began with building an initial search strategy for conducting a pilot search. This was done by first brain-storming and searching glossaries for initial search terms. Next, pilot searches were undertaken in CINAHL Ultimate (EBSCO), Cochrane Library and MEDLINE (PubMed). Pilot results were analyzed at title and abstract level for identification of all relevant keywords and index terms. These were then used in developing the final search query (seen in table 1). Final search was carried out from 4 to 10 May 2024 in MEDLINE (PubMed), CINAHL Ultimate (EBSCO), Medline (EBSCO) and Cochrane Li-brary. In addition, a manual search in the computer archives of one the authors took place. More specifically, one of the authors had done little research about the topic previously as part of her master’s studies. Studies retrieved during this process were searched from her computer and screened for eligibility for this scoping review. Time limits were not set as the aim was to achieve as broad scope as possible of the subject.

Study selection

After undertaking the data search, data selection took place. Duplicates were removed and results were first screened at title and abstract level. Potentially relevant sources were retrieved in full 26 text. Selection continued with screening of full text. During these two screenings, irrelevant re-ports were excluded. Figure 5 shows the Prisma flow chart of selection process. At selection phase, studies involving high intensity resistance training were also categorized as illegible due to different physiological effects than aerobic high-intensity interval training. This decision was also made for cohesion of the study results as resistance HIIT in the studies involved repetitions and sets instead of time intervals like in aerobic HIIT. Selection phase also included brief quality assessment of final reports included. JBI Critical Appraisals tools were utilized here (Barker et al., 2023; Moola et al., 2020).

Data extraction

Data was extracted by using an extraction table/form based on recommendations of JBI (Pollock et al., 2023, p. 522). The extraction form was piloted with three sources from pilot search and necessary changes were made in the final form. Data extracted included author(s), country, study type, aim of the study, participant descriptives, details of methods/intervention protocol, outcome measures and measurement methods and results.

In addition to eight quantitative studies included, one mixed-methods feasibility study was used here to reveal perceptions of pwMS themselves of HIIT training. This study didn’t go through the official data extraction. Relevant findings were highlighted and written as notes in Microsoft Word- formed study diary (that supported the Microsoft Excel-formed notes of study progress).

Synthesis

After data extraction process, synthesis of evidence took place and results are presented in tables and figures. Data was first categorised so that adverse effects of HIIT were separated from other results already during the data extraction phase. Then the results, including beneficial effects, were further categorised accroding to different outcome measures used in included studies. Based on synthesis and as final phase of interpreting and presenting the results, a recommendation was created to work as basis for suitable HIIT-program for pwMS.

Results

Summary of included studies

Initially 139 studies were identified and retrieved from the four databases. 69 duplicates were removed and 62 studies excluded based on the exclusion criteria. Finally, 8 studies from database search and one article from manual search were included. Data selection process can be seen in Prisma flow chart (figure 1). Four of the nine included studies were primary studies and five were secondary analyses.

Figure 1. Prisma flow chart (Eksymä, 2025, p. 26)

Overall, out of 277 pwMS 144 participated in HIIT interventions and 133 did control exercise which was continuous exercise at medium intensity. Four out of five secondary studies utilized the same sample of inpatients at Valens clinic in Switzerland. Most of the participants had relapsing-remitting MS. For 10 participants of mixed-methods study by Humphreys et al. (2022), data of the MS subtypes was not available. Mean age of participants in the studies ranged from 41.6 to 51.02 years for HIIT groups and from 42.8 to 49.7 years for control groups. Mean Expanded Disability Status Scale (EDSS) scores ranged from 2.29 to 4.5 in the HIIT group and from 2.17 to 4.6 in the control group. For this scoping review, mean EDSS score of all HIIT-participants was 4.13 and for those in control groups 4.17. Total of 16 dropouts were reported (HIIT 8, control 8), but in some studies there were inconsistencies and even lack of information in this aspect. More specifically, for one study (Humphreys et al., 2022) locating a version including participant characteristics table was unsuccessful. In addition, study of Feltham et al. (2013) used Barthel index instead of EDSS. More information about study participants can be seen in table 2.

*Inconsistencies in reporting participant numbers, ** Not reported for 10 participants

As it comes to concept, there were some differences in HIIT-interventions used in included studies. High-intensity interval durations ranged from 0.5 min to 3 min and durations of recovery intervals were between 0.5 and 2 min. Intensity of work intervals was between 85% and 100% of maximum heart rate or 70%-90% of peak power. During recovery interval, intensity ranged from 50% to 60% of maximum heart rate or 0% to 50% of peak power between included studies. HIIT-sessions were performed 2-3 times per week and interventions lasted three, six, eight and 12 weeks. In all included studies both interventions and control exercises were performed with cycle ergometer. Outcome measures used in the studies were cardiorespiratory fitness/response, cognitive performance, fatigue, depression and serum biomarkers.

As set in eligibility criteria, context in included studies was rehabilitation. Two studies used outpatient-setting where exercise sessions were undertaken at fitness centre, clinical exercise and rehabilitation centre or at community leisure centre. For other studies, the setting was inpatient at rehabilitation clinic.

Beneficial effects of HIIT for pwMS

This scoping review showed that HIIT has several beneficial effects for pwMS. These focus on cardiorespiratory fitness, factors of cognitive performance and serum biomarkers of MS. Three out of eight studies reported positive and significant changes in these areas. Results regarding fatigue were  heterogeneous.

Cardiorespiratory fitness seemed to improve in all five studies that used it as one of the outcomes. This happened regardless of parameter used (VO2max, VO2peak, VO2norm) (Feltham et al., 2013, pp. 768-770; Rademacher et al., 2021a, p. 4; Wolf et al., 2022, pp. 3-4; Wonneberger & Schmidt, 2019, p. 561; Zimmer et al., 2018, p. 1639.) All three studies that measured cognitive performance found positive changes in processing speed and verbal learning (Rademacher et al., 2021a, pp. 4-5; Rademacher et al., 2021b, pp. 3-6; Zimmer et al., 2018). Processing speed improved in both HIIT and control groups whereas changes in verbal learning were more linked to HIIT groups  (Rademacher et al., 2021b; Zimmer et al., 2018).  Studies also showed signs that HIIT has anti-inflammatory and potentially even neuroprotective effects; studies detected decreases in many serum biomarkers indicating inflammation and neurodegeneration but also increases in levels of neuroprotective agent kynurenic acid (Zimmer et al., 2018, p.1639; Joisten et al., 2021a, p. 1137, Joisten et al., 2021b, p. 2, 4-6). As mentioned earlier, findings regarding fatigue were variable. HIIT was followed by either no significant change in fatigue levels of pwMS or decreased fatigue at least if person with MS was suffering from increased fatigue. In addition to quantitatively measurable outcomes, HIIT sessions brought up such positive  (psychological) changes as increased energy levels, sense of achievement and better ability to cope. (Wonneberger & Schmidt, 2019, p. 561; Humphreys et al., 2022, p. 11; Rademacher et al., 2021a; Wolf et al., 2022.)

Adverse effects of HIIT for pwMS

In addition to mixing results concerning HIIT’s effect on fatigue, some contradiction exists also in other findings especially regarding adverse effects of HIIT; although eight quantitative studies in this review reported barely any symptom exacerbations, qualitative part of the study of Humphreys et al. (2022, pp. 12-13) reported that eight out of 10 participants experienced symptoms like tingling in extremities, blurred vision, partial deafness and one-sided weakness.. In addition, some participants experienced nausea during HIIT-session and muscle ache and feeling wiped out afterwards. Bike as exercise mode was also experienced uncomfortable. Study of Wonneberger and Schmidt (2019, p. 564) also brought up that potential reason for dropouts in their study was overexertion from exercising 3 times a week. This phenomenon was linked to both exercise modalities, HIIT and continuous training.

Recommendation of suitable HIIT for pwMS

Based on this scoping review, HIIT on a cycle ergometer can be considered as part of rehabilitation of people with relapsing-remitting MS with relatively low disability level. Specifically this refers to pwMS  who are  able to walk at least 300 metres unaided and without rest (EDSS ≤4.5). They are able to work full day despite their disabilty, but might need minimal assistance or somewhat limit full acitivity. (Multiple Sclerosis Trust, 2024.) EDSS score of 4.5 was chosen as roof value in this context because among included studies it was the highest mean EDSS score and hence refers to most significant disability on average among those participating in HIIT sessions. HIIT it is generally safe as number of possible adverse effects is rather low. It seems to be beneficial and time-efficient way to exercise cardiorespiratory fitness for pwMS.  Recommendation of suitable HIIT-program by cycle ergometer is presented in figure 2.

Figure 2. Recommendation of suitable HIIT-program for pwMS (Eksymä, 2025, p. 34)

Discussion

Discussion of results

This scoping review revealed that potential benefits of HIIT for pwMS are increasing of cardiorespiratory fitness, improvements in some areas of cognitive performance and positive changes in serum biomarkers indicating anti-inflammatory and even neuroprotective effects.  Heterogeneous findings were discovered regarding effects of HIIT on fatigue, but they seem to show that HIIT might be able to reduce or at least not increase fatigue. In addition to these, HIIT can enhance such positive feelings as sense of achievement and better coping. Logically, these should improve functioning and quality of life of pwMS.

This scoping review shows that HIIT increases cardiorespiratory fitness also among pwMS. This is meaningful finding considering that cardiorespiratory fitness of pwMS is lower than general population and they also have more inactivity-related comorbidities. Improved cardiorespiratory fitness has secondary health benefits (Motl et al., 2017, p. 849; Wonneberger & Schmidt, 2019, p. 563) and evidence suggests that HIIT is either superior or equally efficient than continuous training in improving cardiovascular risk factors (Campbell et al., 2018). Increased cardiorespiratory fitness is in line with the findings of Atakan et al. (2021, p. 15), Campbell et al. (2018, p. 22), Halabchi et al. (2017, p. 3), Latimer-Cheung et al. (2013, p. 1825), Milanovic et al. (2015, p. 1479) and Platta et al. (2016, p. 1571) who have shown exercise-induced improvements in both healthy adults and populations with multiple sclerosis, obesity, cancer and metabolic syndrome. In addition, Clifford et al. (2023, pp. 10─12) found that HIIT-intervention improved cardiorespiratory fitness and significantly reduced post-operative complications in population going through major surgery. However, there is no clear consensus of how much VO2peak should increase to produce clinically significant improvements in pwMS. Increase of about 3.5ml/min/kg is suggested as it reduces mortality by 13 % and incidence of cardiovascular diseases by 15% but in healthy people (Kodama et al. 2009 in Wonneberger and Schmidt 2019, p. 563). 

Evidence of benefits of exercise on cognitive performance among pwMS is inconsistent as the review of Sandroff et al., (2016, p. 284) reveals. On the other hand, these researchers found possible association between better physical fitness and better cognitive performance. All the studies measuring cognitive outcomes in this  study found beneficial effects; some improvements only took place in HIIT-intervention group, but many were observed also in active control groups. However, Langeskov-Christensen et al. (2021, p. 1594) found that progressive aerobic exercise involving interval training had no effect on cognitive domains in pwMS. The exception was clinically relevant improvement in processing speed among cognitively impaired subgroup. Similar findings were observed in this  review in the study of Rademacher et al. (2021b, p. 5) as baseline lower cognitive status and HIIT-group predicted bigger improvements in verbal learning.

HIIT’s positive effects on different serum biomarkers and possibly having anti-inflammatory or neuroprotective influence is partly supported by meta-analyses of Shobeiri et al. (2022) and review of Dalgas and Stenager (2012). Shobeiri et al. (2021, p. 10─14) found that physical activity (aerobic, combined and anaerobic) increases peripheral levels of brain-derived neurotrophic factor (BDNF) in pwMS which can indicate neuroregenerative or neuroprotective effects of exercising. Dalgas and Stenager (2012, p. 93) also concluded that although findings are conflicting, exercise may have an impact on levels of different neurotrophic factors with neuroprotective properties in pwMS. On the other hand, it still can’t be concluded that exercise would have disease-modifying effects in pwMS (Proschinger et al., 2022, p. 2922).

Variable findings were discovered regarding effects of HIIT on fatigue. Whereas no significant change was seen in the studies of Wolf et al. (2022) and (Rademacher et al., 2021a) two other research groups (Humphreys etal., 2022; Wonneberger & Schmidt, 2019) showed reduced fatigue in their trials. Earlier findings about effects of exercise on fatigue among pwMS are equally inconsistent although they seem to favor slightly more the findings of latter researchers. Both Gallien et al. (2007, p. 375) and Latimer-Cheung et al. (2013, p. 1825) stated in their reviews that exercise can improve fatigue. Learmonth and Motl (2016, p. 1235) disagree with this view and list increased fatigue as an adverse consequence of exercise for pwMS. One of the reasons for this inconsistency at least in this study, might be use of different measuring methods of fatigue. In larger scale, variable dosage of exercise might confuse findings.

The number of reported adverse events in this scoping review was very low. PwMS were mostly able to participate in HIIT sessions and complete the programs mainly without significant adverse events. This is accordingly with Pilutti et al. (2014, p. 7) and Halabchi et al. (2017, p. 9) who declare exercising as safe for pwMS. On the other hand, symptom exacerbation, nausea and discomfort were adverse effects experienced by some participants. There was also indication of overexertion and challenge with correct execution of HIIT session. Atakan et al. (2021, p. 4) seem to agree with this as they claim that high exertion that HIIT requires is too strenuous for sedentary people. It should be mentioned that Uthoff phenomenon seemed to be present in the study of Humphreys et al. (2022) as participants reported of short-term symptom exacerbation. Although it has no lasting effects, it can be very unpleasant and reduce willingness to engage in more permanent active behaviour (Richardson et al.2020, p. 4).

Although heart rate (HR) might be the easiest way to measure intensity, with pwMS there is a risk for unreliable measuring due to possible impairment in autonomic regulation of HR and unreliable baseline measurement (untrained person finishing the test because of leg fatigue instead of reaching true HRmax). Due to this, RPE scale can be used as additional measurement method. (Atakan et al., 2021, p. 3; Halabchi et al., 2017, p. 6.) Supervision is advisable in case of serious medical event. Risk for Uthoff syndrome/short-term symptom exacerbation exists (Humphreys et al., 2022, pp. 12-13) and person with MS willing to try HIIT should acknowledge it. The risk of symptom exacerbation and rising core temperature can be minimized by using cooling vest and properly air-conditioned environment (Richardson et al., 2020, p. 4).

Strengths and limitations

Data search in this scoping review successfully resulted in nine subject-related research articles which gave good amount of data to work with in relation to human resources available for the process. Regardless of limitations and some qualitative issues, authors were able to fulfill the sub-objective three of the study and produce rough guideline for carrying out HIIT sessions for pwMS. All included studies of this scoping review utilised the same equipment (cycle ergometer) for performing HIIT which facilitated the making of previously mentioned guidelines. Strength of this study is also that careful recording of research process and results was kept, including utilizing existing forms and guidelines for scoping review and data.

What it comes to limitation of this scoping review, there was a lack of diversity and variability in findings as many of included studies used the similar setting and same sample of participants. This has an impact on generalizability of the results. Furthermore, most participants had relapsing-remitting MS so less is known about suitability and effects of HIIT for people with progressive multiple sclerosis. Furthermore, any of included studies didn’t report activity levels of the participants so it is impossible to conclude whether HIIT is advisable for pwMS of all fitness levels. For most of the secondary analysis -studies, locating the primary study was unsuccessful regardless of the effort. Hence, it seemed that for example reporting dropouts and adverse events was incomplete. Related to this issue with primary studies, was that ability and decision to use only open/free access research probably resulted in missing some relevant studies.  To increase reliability of findings, two instead of one researcher carrying out study selection and data extraction would have been justifiable.

Recurring issues with the quality of included studies were partial lack of blinding and missing of proper follow up period after intervention. All randomized controlled trials included used only single blinding (blinding of assessors) which, on the other hand, is understandable since blinding of participants and those delivering the interventions would be challenging or even impossible in this kind of intervention setting. In addition to lack of follow up period, duration of majority of the studies was very short (3 weeks). Hence, it is impossible to make conclusions of persistence or longer-term effects of HIIT among pwMS. Reporting and dealing with confounding factors were inadequate throughout the sample which weakens repeatability and reliability of the studies. Finally, since some of the studies were short reports and also secondary analyses, some elements of the appraisal remained unclear if retrieving primary study was unsuccessful.

Future research

Future research should focus on investigating HIIT’s effect on MS-symptoms more precisely and maybe more broadly. For example, no study using spasticity as outcome was found during this thesis process. Studies need to include more people with primary or secondary progressive multiple sclerosis, and higher disability levels (≥5.0 EDSS), as participants. Participants’ self-evaluated performance should be also a factor to consider in future studies. This subject also needs more primary studies, especially interventions lasting longer than 3 weeks, and happening in outpatient setting or so that other therapies or treatments as confounding factors can be minimized as well as ethically possible. Finally, all the studies here used cycle ergometer in performing HIIT-sessions so studying other methods for HIIT training is relevant.

Conclusion

To conclude, high-intensity interval training is generally suitable for pwMS who have relapsing-remitting form of the disease and whose disability level is relatively low (EDSS ≤4.5). Benefits seem to outweigh adverse effects, but individual differences, preferences and health should be considered. More research of the subject is needed especially regarding different types of MS and more variable disability levels.

Acknowledgement

The manuscript is based on a thesis for a Master’s degree in Sport and Exercise Physiotherapy at Jamk UAS.

Conflict of Interest

The authors declare no conflict of interest.

Data availability statement:

Data supporting the findings of this review were obtained from published articles included in the scoping review. The data extraction tables are available in the supplementary materials. Supplementary materials are available upon request from the journal’s editorial office.

Contact Person

Jaana Paltamaa, Jamk University of Applied Sciences, The School of Health and Social Studies, Rehabilitation Institute

firstname.lastname@jamk.fi

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URN: http://urn.fi/urn:nbn:fi:jamk-issn-2954-1069-15