Energy cost of walking and exertional dyspnea in multiple sclerosis

Metabolic costs of walking and arm reaching in persons with mild multiple sclerosis

Movement slowness is a common and disruptive symptom of multiple sclerosis (MS). A potential cause is that individuals with MS slow down to conserve energy as a behavioral adjustment to heightened metabolic costs of movement. To investigate this prospect, we measured the metabolic costs of both walking and seated arm reaching at five speeds in persons with mild MS (pwMS; n = 13; 46.0 ± 7.7 yr) and sex- and age-matched controls (HCs; n = 13; 45.8 ± 7.8 yr). Notably, the cohort of pwMS was highly mobile and no individuals required a cane or aid when walking. We found that the net metabolic power of walking was approximately 20% higher for pwMS across all speeds (P = 0.0185). In contrast, we found no differences in the gross power of reaching between pwMS and HCs (P = 0.492). Collectively, our results suggest that abnormal slowness of movement in MS-particularly reaching-is not the consequence of heightened effort costs and that other sensorimotor mechanisms are playing a considerable role in slowing.NEW & NOTEWORTHY Individuals with multiple sclerosis (MS) often move more slowly than those without the disease. A possible cause is that movements in MS are more energetically expensive and slowing is an adaptation to conserve metabolic resources. Here, we find that while walking is more costly for persons with MS, arm-reaching movements are not. These results bring into question the driving force of movement slowness in MS and implicate other motor-related networks contributing to slowing.

Acute Thermoregulatory and Cardiovascular Response to Submaximal Exercise in People With Multiple Sclerosis

Background

Heat sensitivity occurs in a high percentage of people with multiple sclerosis (PwMS), in response to environmental or exercise-induced increase in body temperature. However, the kinetic and magnitude of adaptation of the internal load and of the core body temperature (CBT) to a submaximal continuous exercise has been poorly addressed in PwMS; this may be relevant for the brief exercise bouts usually occurring in normal daily life. The aim of this work was to evaluate whether multiple sclerosis influences the acute adaptation of the internal load, the CBT and the perceptual load in response to a constant submaximal work step.

Methods

CBT has been continuously monitored (0.5 Hz) by a validated wearable heat-flux sensor and electrocardiography was recorded (250 Hz) by a wearable device during a standard 6-minute walk test (6MWT) in 14 PwMS (EDSS, 4.7 ± 1.2; disease duration: 13.0 ± 10.2 years; m ± SD) and 14 age, sex and BMI-matched healthy subjects (HS). The rate of perceived exertion (RPE) of the lower limbs was assessed during the 6MWT by the Borg scale (6-20).

Results

As expected, PwMS walked a significantly shorter distance (361 ± 98 m) than the HS group (613 ± 62 m, p<0.001 vs PwMS). However, the kinetics of adaptation of CBT and the magnitude of CBT change from baseline did not differ between groups. Similarly, heart rate (HR) kinetics and HR change from baseline were comparable between groups during the 6MWT. Finally, lower limbs RPE gradually increased during the exercise test, but without significant differences between groups.

Conclusion

The internal load, the metabolic heat production, and the perceptive load due to a standard submaximal walking exercise seems to be preserved in PwMS, suggesting a comparable acute heat production and dissipation during exercise. Therefore, it is unlikely that the different distance achieved during the 6MWT may be caused by altered thermoregulatory responses to exercise. Rather, this appears to be a consequence of the known increased energy cost of locomotion in PwMS.

Development and deployment of cyclical focal muscle vibration system to improve walking performance in multiple sclerosis

Vibration, a potent mechanical stimulus for activating muscle spindle primary afferents, may improve gait performance in persons with multiple sclerosis (MS), but has yet to be developed and deployed for multiple leg muscles with application during walking training. This study explored the development of a cyclic focal muscle vibration (FMV) system, and the deployment feasibility to correct MS walking swing phase deficits in order to determine whether this intervention warrants comprehensive study. The system was deployed during twelve, two-hour sessions of walking with cyclic FMV over six weeks. Participants served as their own control. Blood pressure, heart rate, walking speed, kinematics (peak hip, knee and ankle angles during swing), toe clearance, and step length were measured before and after deployment with blood pressure and heart rate monitored during deployment. During system deployment, there were no untoward sensations and physiological changes in blood pressure and heart rate, and volitional improvements were found in walking speed, improved swing phase kinematics, toe clearance and step length. This FMV training system was developed and deployed to improve joint flexion during walking in those with MS, and it demonstrated feasibility and benefits. Further study will determine the most effective vibration frequency and dose, carryover effects, and those most likely to benefit from this intervention.

Sex-Based Differences in Oxygen Cost of Walking and Energy Equivalents in Minimally Disabled Individuals With Multiple Sclerosis and Controls

BACKGROUND

Elevated oxygen cost of walking and energy equivalents are reported for highly and moderately disabled individuals with multiple sclerosis (MS). However, less is known about minimally impaired individuals. Moreover, no sex-based data on the metabolic rates of individuals with MS are available. In this cross-sectional study, the metabolic rates and temporospatial parameters of gait during overground walking in minimally disabled individuals with MS versus matched controls were quantified and whether sex-based differences occur was examined.

METHODS

Sixty-nine minimally impaired adults with MS (37, relapsing-remitting MS [RRMS]; 32, clinically isolated syndrome [CIS]) and 25 matched controls completed two 6-minute walking bouts at comfortable and fast speeds. The oxygen cost of walking, energy equivalents, and respiratory exchange ratio were recorded through breath-by-breath open-circuit spirometry. Gait analysis was performed via a portable electronic walkway.

RESULTS

At comfortable but not at fast speed, men with RRMS showed higher oxygen cost of walking than men with CIS (+17.9%, P = .04) and male controls (+21.3%, P = .03). In the RRMS group, men showed higher oxygen cost of walking (+19.2%, P = .04) and energy equivalents (+19.2%, P = .02) than women. Elevated oxygen cost of walking and energy equivalents in men were paralleled by significantly larger base of support and step time asymmetry during walking.

CONCLUSIONS

Metabolic demands are elevated while walking in minimally disabled individuals with RRMS. Furthermore, higher energy demands occur in men, probably due to increased step symmetry and base of support. Clinicians are advised to follow energy expenditure metrics collected while walking because they can indicate a decrease in fitness, even in the early phase of MS.

Alterations in Leg Muscle Glucose Uptake and Inter-Limb Asymmetry after a Single Session of tDCS in Four People with Multiple Sclerosis

Asymmetrical lower limb weakness is an early symptom and significant contributor to the progressive worsening of walking ability in people with multiple sclerosis (PwMS). Transcranial direct current stimulation (tDCS) may effectively increase neural drive to the more-affected lower limb and, therefore, increase symmetrical activation. Four PwMS (1 female, age range: 27–57) underwent one session each of 3 mA or SHAM tDCS over the motor cortex corresponding to their more-affected limb followed by 20 min of treadmill walking at a self-selected speed. Two min into the treadmill task, the subjects were injected with the glucose analog [¹⁸F]fluorodeoxyglucose (FDG). Immediately after treadmill walking, the subjects underwent whole-body positron emission tomography (PET) imaging. Glucose uptake (GU) values were compared between the legs, the spatial distribution of FDG was assessed to estimate glucose uptake heterogeneity (GUh), and GU asymmetry indices (AIs) were calculated. After tDCS, GU was altered, and GUh was decreased in various muscle groups in each subject. Additionally, AIs went from asymmetric to symmetric after tDCS in the subjects that demonstrated asymmetrical glucose uptake during SHAM. These results indicate that tDCS improved GU asymmetries, potentially from an increased neural drive and a more efficient muscle activation strategy of the lower limb in PwMS.

Aerobic reserve capacity in multiple sclerosis-Preliminary evidence

OBJECTIVES

Aerobic reserve capacity reflects the available energy for performing everyday life tasks, and it has been studied in older adult populations. This preliminary study examined proof of concept and measurement of aerobic reserve capacity in multiple sclerosis (MS).

MATERIALS & METHODS

Twenty-one fully ambulatory people with MS performed a maximal, cardiopulmonary exercise test (CPET). We calculated aerobic reserve capacity based on the difference between peak aerobic power (VO_2peak ) and first stage oxygen consumption (VO₂ ). Participants completed assessments for disability (Expanded Disability Status Scale, EDSS), cognition (Symbol Digit Modalities Test, SDMT), mood (Beck Depression Inventory, BDI), walking endurance (six-minute walk distance, 6MWD), walking speed (Timed Twenty-Foot Walk, T25FW), impact of MS (Multiple Sclerosis Impact Scale, MSIS-29), and anthropometric measurements (height and weight).

RESULTS

Aerobic reserve capacity was 9.3 ± 3.7 ml/kg/min. Aerobic reserve capacity was positively associated with VO_2peak (ρ = .67, p < .01), time to exhaustion (ρ = .63, p < .01), and SDMT (ρ = .51, p < .05). Aerobic reserve capacity was negatively associated with BMI (ρ = -.62, p < .01) and RHR (ρ = -0.47, p < .05).

CONCLUSION

We provide preliminary evidence that aerobic reserve capacity is a feasible outcome derived from maximal CPET (eg, modified Balke protocol) in MS. Aerobic reserve capacity was associated with clinically relevant outcomes and could become an important outcome for rehabilitation in future research.

Association of walking energetics with amyloid beta status: Findings from the Baltimore Longitudinal Study of Aging

INTRODUCTION

Higher energetic costs for mobility predict gait speed decline. Slow gait is linked to cognitive decline and Alzheimer's disease (AD). Whether the energetic cost of walking is linked to AD pathology is unknown. We investigated the cross-sectional association between the energetic cost of walking, gait speed, and amyloid beta (Aβ) status (+/-) in older adults.

METHODS

One hundred forty-nine cognitively normal adults (56% women, mean age 77.5 ± 8.4 years) completed customary-paced walking assessments with indirect calorimetry and 11C-Pittsburgh compound B positron emission tomography. Logistic regression models examined associations adjusted for demographics, body composition, comorbid conditions, and apolipoprotein E ε4.

RESULTS

Each 0.01 mL/kg/m greater energy cost was associated with 18% higher odds of being Aβ+ (odds ratio [OR] = 1.18; 95% confidence interval [CI]: 1.04 to 1.34; P = .011). These findings were not observed when investigating gait speed (OR = 0.99; 95% CI: 0.97 to 1.01; P = .321).

DISCUSSION

High energetic cost of walking is linked to AD pathology and may be a potential target for therapeutic intervention.

The Relationship Between Walking Speed and the Energetic Cost of Walking in Persons With Multiple Sclerosis and Healthy Controls: A Systematic Review

BACKGROUND

Persons with multiple sclerosis (pwMS) experience walking impairments, characterized by decreased walking speeds. In healthy subjects, the self-selected walking speed is the energetically most optimal. In pwMS, the energetically most optimal walking speed remains underexposed. Therefore, this review aimed to determine the relationship between walking speed and energetic cost of walking (Cw) in pwMS, compared with healthy subjects, thereby assessing the walking speed with the lowest energetic cost. As it is unclear whether the Cw in pwMS differs between overground and treadmill walking, as reported in healthy subjects, a second review aim was to compare both conditions.

METHOD

PubMed and Web of Science were systematically searched. Studies assessing pwMS, reporting walking speed (converted to meters per second), and reporting oxygen consumption were included. Study quality was assessed with a modified National Heart, Lung and Blood Institute checklist. The relationship between Cw and walking speed was calculated with a second-order polynomial function and compared between groups and conditions.

RESULTS

Twenty-nine studies were included (n = 1535 pwMS) of which 8 included healthy subjects (n = 179 healthy subjects). PwMS showed a similar energetically most optimal walking speed of 1.44 m/s with a Cw of 0.16, compared with 0.14 mL O₂/kg/m in healthy subjects. The most optimal walking speed in treadmill was 1.48 m/s, compared with 1.28 m/s in overground walking with a similar Cw.

CONCLUSION

Overall, the Cw is elevated in pwMS but with a similar energetically most optimal walking speed, compared with healthy subjects. Treadmill walking showed a similar most optimal Cw but a higher speed, compared with overground walking.

Different Effects of Transcranial Direct Current Stimulation on Leg Muscle Glucose Uptake Asymmetry in Two Women with Multiple Sclerosis

Asymmetrical lower limb strength is a significant contributor to impaired walking abilities in people with multiple sclerosis (PwMS). Transcranial direct current stimulation (tDCS) may be an effective technique to enhance cortical excitability and increase neural drive to more-affected lower limbs. A sham-controlled, randomized, cross-over design was employed. Two women with MS underwent two 20 min sessions of either 3 mA tDCS or Sham before 20 min of treadmill walking at a self-selected speed. During walking, the participants were injected with the glucose analogue, [¹⁸F] fluorodeoxyglucose (FDG). Participants were then imaged to examine glucose metabolism and uptake asymmetries in the legs. Standardized uptake values (SUVs) were compared between the legs and asymmetry indices were calculated. Subject 2 was considered physically active (self-reported participating in at least 30 min of moderate-intensity physical activity on at least three days of the week for the last three months), while Subject 1 was physically inactive. In Subject 1, there was a decrease in SUVs at the left knee flexors, left upper leg, left and right plantar flexors, and left and right lower legs and SUVs in the knee extensors and dorsiflexors were considered symmetric after tDCS compared to Sham. Subject 2 showed an increase in SUVs at the left and right upper legs, right plantar flexors, and right lower leg with no muscle group changing asymmetry status. This study demonstrates that tDCS may increase neural drive to leg muscles and decrease glucose uptake during walking in PwMS with low physical activity levels.

Comfortable walking speed and energy cost of locomotion in patients with multiple sclerosis

Comfortable walking speed and energy cost of walking are physiological markers of metabolic activity during gait. People with multiple sclerosis are characterized by altered gait biomechanics and energetics, related to the degree of disability and spasticity, which lead to an increased energy cost of walking. Several studies concerning the energy cost of walking in multiple sclerosis have been published. Nevertheless, differences in protocols and characteristics of the sample have led to different outcomes. The aim of the present meta-analysis is to summarize results from studies with specific inclusion characteristics, and to present data about the comfortable walking speed and the energy cost of walking at that speed. Moreover, a detailed discussion of the potential mechanisms involved in the altered metabolic activity during exercise was included. A total of 19 studies were considered, 12 of which were also part of the quantitative analysis. Despite the strict selection process, high between-group heterogeneity was found for both outcomes. Nevertheless, the overall results suggest a pooled mean comfortable walking speed of 1.12 m/s (95% CI 1.05-1.18) and energy cost of 0.19 mLO₂/kg/m (95% CI 0.17-0.21). These findings support the results of previous studies suggesting that energy cost of walking may be increased by 2-3 times compared to healthy controls (HC), and encourage the use of this marker in association with other parameters of the disease.

Prediction of oxygen uptake during walking in ambulatory persons with multiple sclerosis

People with multiple sclerosis (MS) have an increased rate of gross oxygen uptake (gross-VO2) during treadmill walking, and their gross-VO2 may further vary with walking impairment. This study attempted to develop an equation for predicting gross-VO2 from walking speed and an index of walking impairment in persons with MS and examine its accuracy. Gross-VO2 was measured with open-circuit spirometry in 43 persons with MS (47 +/- 9 yr; 38 women) during five treadmill walking trials, each lasting 6 min, at 2.0, 2.5, 3.0, 3.5, and 4.0 mph (0.89, 1.12, 1.34, 1.56, and 1.79 m/s). The 12-Item Multiple Sclerosis Walking Scale (MSWS-12) and the single-item Patient Determined Disease Steps scale (PDDS) provided indices of walking impairment. Multilevel modeling with random intercepts and slopes showed significant effects of speed and MSWS-12 on gross-VO2 (p </= 0.014; R(2) = 0.70). PDDS was not a significant predictor. Gross-VO2 estimated by the regression equation did not differ from actual gross-VO2 across speeds. Mean absolute prediction error across speeds was 9.1%. The Bland-Altman plot indicated zero mean difference between actual and predicted gross-VO2 with modest 95% confidence intervals. Therefore, speed and MSWS-12 score are jointly highly predictive of gross-VO2 during treadmill walking in persons with MS.

Cross-validation of oxygen uptake prediction during walking in ambulatory persons with multiple sclerosis

BACKGROUND

An equation for predicting the gross oxygen uptake (gross-VO2) during walking for persons with multiple sclerosis (MS) has been developed. Predictors included walking speed and total score from the 12-Item Multiple Sclerosis Walking Scale (MSWS-12).

OBJECTIVE

This study examined the validity of this prediction equation in another sample of persons with MS.

METHODS

Participants were 18 persons with MS with limited mobility problems (42 ± 13 years; 14 women). Participants completed the MSWS-12. Gross-VO2 was measured with open-circuit spirometry during treadmill walking at 2.0, 3.0, and 4.0 mph (0.89, 1.34, and 1.79 m·s(-1)).

REULTS

Absolute percent error was small: 8.3 ± 6.1% , 8.0 ± 5.6% , and 12.2 ± 9.0% at 2.0, 3.0, and 4.0 mph, respectively. Actual gross-VO2 did not differ significantly from predicted gross-VO2 at 2.0 and 3.0 mph, but was significantly higher than predicted gross-VO2 at 4.0 mph (p <  0.001). Bland-Altman plots indicated nearly zero mean difference between actual and predicted gross-VO2 with modest 95% confidence intervals at 2.0 and 3.0 mph, but there was some underestimation at 4.0 mph.

CONCLUSIONS

Speed and MSWS-12 score provide valid prediction of gross-VO2 during treadmill walking at slow and moderate speeds in ambulatory persons with MS. However, there is a possibility of small underestimation for walking at 4.0 mph.

Can aerobic treadmill training reduce the effort of walking and fatigue in people with multiple sclerosis: a pilot study

Impaired mobility in multiple sclerosis (MS) is associated with high-energy costs and effort when walking, gait abnormalities, poor endurance and fatigue. This repeated measures trial with blinded assessments investigated the effect of treadmill walking at an aerobic training intensity in 16 adults with MS. The intervention consisted of 12 sessions of up to 30 minutes treadmill training (TT), at 55–85% of age-predicted maximum heart rate. The primary outcome measure was walking effort, measured by oxygen consumption (mL/kg per metre), during treadmill walking at comfortable walking speed (CWS). Associated changes in gait parameters using the ‘Gait-Rite’ mat, 10-m time and 2-minute distance, and Fatigue Severity Scale were examined. Following training, oxygen consumption decreased at rest (P = 0.008), CWS increased (P = 0.002), and 10-m times (P = 0.032) and walking endurance (P = 0.020) increased. At increased CWS, oxygen consumption decreased (P = 0.020), with a decreased time spent in stance in the weaker leg (P = 0.034), and a greater stride distance with the stronger leg (P = 0.044). Reported fatigue levels remained the same. Aerobic TT presents the opportunity to alter a motor skill and reduce the effort of walking, whilst addressing cardiovascular de-conditioning, thereby, potentially reducing effort and fatigue for some people with MS.

Energy cost of walking, symptomatic fatigue and perceived exertion in persons with multiple sclerosis

A higher energy cost of walking (Cw) is sometimes observed in MS, and could contribute to fatigue. The purpose of this study was to compare Cw at three speeds in MS and controls, and determine the effects of walking speed on fatigue and perceived exertion. We hypothesized that MS would have higher Cw, fatigue and exertion during walking than controls. Ten persons with MS and 14 controls of similar age and physical activity levels were studied. Oxygen consumption (VO2) was obtained at rest and during treadmill walking at 0.6 and 1.4ms(-1), and preferred speed. Cw was calculated as net VO2:velocity. Fatigue and exertion were assessed using the visual analog fatigue and modified Borg scales, respectively. Preferred treadmill speed was not different between groups. Cw was higher in MS than controls across walking speeds (p=0.003), with a group-by-speed interaction indicating higher Cw in MS at 0.6ms(-1) (p=0.001), but not at preferred speed or 1.4ms(-1). MS reported greater fatigue (p=0.001) and exertion (p=0.004) at all speeds. Despite similar preferred speeds, and Cw at preferred and fast speeds, MS exhibited higher fatigue and exertion at all walking speeds. These results suggest that increased energy demands in MS are most notable at low speeds such as those used in everyday activities, which may contribute to fatigue over the day.

Evidence for a central mechanism in the process of fatigue in people with multiple sclerosis

The study aimed to establish quantitative and qualitative aspects of fatigue among a group of people with multiple sclerosis (MS) who had identified fatigue as a troublesome symptom and a control group of healthy adults. An interview, a fatigue diary and a fatigue-inducing experiment were designed and the Nottingham Health Profile was employed. People with MS experienced significantly more fatigue than healthy adults, on a daily basis. Factors noted to cause and to relieve fatigue were similar in people with MS and healthy adults. The only differences were that a hot bath improved fatigue in healthy adults and accentuated it in people with MS and that more of the healthy adults mentioned lack of sleep as a cause of fatigue. Physiological muscular fatigue during a quadriceps test was of similar magnitude in the two studied groups but the perceived fatigue levels were disproportionally high in the patient group. The results support the view that central mechanisms are responsible both for muscle weakness and for the sense of fatigue experienced so frequently in multiple sclerosis. This central mechanism is likely to reside in motor pathways within the nervous system. Further studies, measuring corticomotor conduction times, motor unit firing frequencies and metabolic factors, are recommended.

Comparison of energy consumption in different clinical forms multiple sclerosis with normal subjects (cohort study)

BACKGROUND

Multiple sclerosis (MS) is one of the most common joint disorders that influence walking performance.

OBJECTIVES

The objectives are to determine if energy consumption of three different clinical forms of MS differs from each other. Is there any difference between MS and normal subjects? Is there an association between the Physiological Cost Index (PCI) and the Expanded Disability States Scale (EDSS)?

METHODS

MS subjects (EDSS>4) were separated in three groups based on the Ashworth and Ataxia scales, including ataxic (n=16), spastic (n=15) and ataxic-spastic (n=14). In addition, 13 age-and-gender-matched healthy subjects were used as the control group. A Heart Rate (HR) Polar Electro Finland was used to record the heart rate during resting and walking. The energy consumption was measured based on PCI. ANOVA, MANOVA, Post-hoc Tukey analysis and Pearson correlations were used for statistical analysis (P<0.05).

RESULTS

There was a significant difference between the walking speeds of normal (76.05±5.70m/min) with ataxic (36.78±12.68m/min), spastic (34.45±16.32m/min) and ataxic-spastic (27.21±14.76m/min) groups (P<0.001). There were no significant differences between the resting HR and walking HR of four groups, and no significant difference between the PCI of ataxic, spastic and normal groups (P>0.1). The correlation between PCI and EDSS was 0.65 (P<0.001).

CONCLUSION

The performance of the cardiovascular system in MS subjects was the same as normal subjects. Their energy consumption increased significantly due to a decrease in their walking speed. It seems that the weakness of muscles of the lower extremity and spasticity of knee extensors play a significant role in this regard.

Respiratory dysfunction in multiple sclerosis

Respiratory dysfunction frequently occurs in patients with advanced multiple sclerosis (MS), and may manifest as acute or chronic respiratory failure, disordered control of breathing, respiratory muscle weakness, sleep disordered breathing, or neurogenic pulmonary edema. The underlying pathophysiology is related to demyelinating plaques involving the brain stem or spinal cord. Respiratory complications such as aspiration, lung infections and respiratory failure are typically seen in patients with long-standing MS. Acute respiratory failure is uncommon and due to newly appearing demyelinating plaques extensively involving areas of the brain stem or spinal cord. Early recognition of MS patients at risk for respiratory complications allows for the timely implementation of care and measures to decrease disease associated morbidity and mortality.

Neurological disability and its association with walking impairment in multiple sclerosis: brief review

SUMMARY 

Neurological disability and walking impairment are two common, co-varying consequences of multiple sclerosis (MS) that can result in substantial patient burden for daily activities and quality of life. Indeed, neurological disability and walking impairment are driven by pathological changes in the central nervous system, and measurement of walking function is a common method of monitoring the progression of disease and neurological disability. The existing data indicate that the presence of walking impairments range from performance through real-world outcomes based on comparison of MS versus healthy controls, and walking impairments become worse with increasing severity of neurological disability (i.e., progression). Accordingly, researchers and clinicians have considered both pharmaceutical and rehabilitation approaches for managing walking impairment in MS. Both approaches yield beneficial effects on walking outcomes, although the majority of research has focused on exercise training rather than pharmaceutical interventions. Overall, this underscores the importance of continued efforts toward identifying approaches for preventing, forestalling and restoring walking function in persons with MS across the spectrum of neurological disability and its progression.

Experiences of functional electrical stimulation (FES) and ankle foot orthoses (AFOs) for foot-drop in people with multiple sclerosis

PURPOSE

A constructivist phenomenological study explored impacts of ankle foot orthoses (AFOs) or functional electrical stimulation (FES) on people with foot-drop from multiple sclerosis (MS).

METHOD

Focus groups following topic guides were analysed using interpretative phenomenological analysis, with researcher reflexivity, participant verification and peer checking of analysis. Participants with sustained use of the devices (under 2 y) were invited from two quantitative studies that (a) investigated immediate FES effects (n = 12) and (b) compared habitual use of AFO (n = 7) or FES (n = 6). Two focus groups addressed AFO (n = 4) and FES (n = 6) experiences.

RESULTS

Similar numbers of positive and negative aspects were described for AFO and FES. Both reduced fatigue, improved gait, reduced trips and falls, increased participation, and increased confidence; greater balance/stability was reported for AFOs, and increased walking distance, fitness and physical activity for FES. Barriers to both included avoiding reliance on devices and implications for shoes and clothing; a non-normal gait pattern was reported for AFO, and difficulties of application and limitations in the design of FES. However, participants felt the positives outweighed the negatives.

CONCLUSIONS

Participants felt benefits outweighed the drawbacks for AFO and FES; greater understanding of user preferences and satisfaction may increase likelihood of usage and efficacy. Implications for Rehabilitation Interventions to reduce the impacts of foot-drop in people with multiple sclerosis (MS) are important to optimise physical activity participation and participation in life; they include ankle foot orthoses (AFOs) and functional electrical stimulation (FES). Research is lacking regarding user satisfaction and perceived outcomes, therefore, two separate focus groups were conducted from a constructivist phenomenological perspective to explore the impacts of AFOs (n = 4) and FES (n = 6) on people with foot-drop from MS. Some similar positive aspects of AFO and FES use were described, including reduced fatigue, improved gait and fewer trips and falls, while common barriers included finding the device cumbersome, uncomfortable, and inconvenient, with some psychological barriers to their use. On balance, the impacts of the devices on improving activities and participation were more important for participants than practical barriers, highlighting the importance of combining understanding of individual experiences and preferences with clinical decision-making when prescribing a device to manage foot-drop.

Oxygen cost of walking in persons with multiple sclerosis: disability matters, but why?

Background. The oxygen cost (O₂ cost) of walking is elevated in persons with MS, particularly as a function of increasing disability status. Objective. The current study examined symptomatic (i.e., fatigue, pain, anxiety, and depression) and gait (i.e., velocity, cadence, and step length) variables that might explain why disability status is associated with O₂ cost of walking in persons with MS. Materials and Methods. 82 participants completed the Patient-Determined Disease Steps, Fatigue Severity Scale, McGill Pain Questionnaire, and Hospital Anxiety and Depression Scale and undertook 2 trials of walking on a GAITRite electronic walkway. Participants then completed a six-minute walk test with concurrent assessment of expired gases for quantifying oxygen consumption and O₂ cost of walking. Results. Disability (r = 0.55) as well as fatigue (r = 0.22), gait velocity (r = −0.62), cadence (r = −0.73), and step length (r = −0.53) were associated with the O₂ cost of walking. Cadence (β = −0.67), but not step length (β = −0.14) or fatigue (β = −0.10), explained the association between disability and the O₂ cost of walking. Conclusions. These results highlight cadence as a target of rehabilitation for increasing metabolic efficiency during walking among those with MS, particularly as a function of worsening disability.

Energy expenditure during everyday activities--a study comparing people with varying mobility limitations due to multiple sclerosis and healthy controls

PURPOSE

To investigate energy expenditure of people with multiple sclerosis (MS) during everyday activities.

METHODS

Fifteen healthy controls, 19 people with MS who used at most a stick to walk outdoors (MS-A), and 11 people with MS who used bilateral support for gait (MS-B) completed scripted everyday activities. A portable indirect calorimetry unit calculated energy expenditure. Steps were counted from video.

RESULTS

There was no significant difference in kcal between the three groups (ANOVA: F(2, 42) = 2.877, p = 0.067). There was a significant difference in steps: F(2, 42) = 17.93, p < 0.001. (Controls-MS-A 470.5, 95% CI 85.2, 855.7, Control-MS-B 1091.3, 95% CI 648.5, 1534.1, MS-A-MS-B 620.8, 95% CI 198.2, 1043.4.) Energy cost of movement was estimated by dividing kcal by steps. The Kruskal-Wallis analysis found significant difference for total (x(2 )= 11.726, df2, p = 0.003), Walking (x(2 )= 9.01, p = 0.011), Stairs (x(2 )= 16.436, 2, p < 0.001). Post-hoc analysis revealed significant differences between MS-B group and control and MS-A groups.

CONCLUSIONS

People with MS do not use more energy than healthy controls during everyday activities at a self-selected pace. People with MS take significantly fewer steps during activities of daily living's. People who use bilateral support for gait have greater energy cost per step for walking and stairs activities. Implications for Rehabilitation This study found that the energy cost of movement is greater for people with MS with significant disability. Energy expenditure is an important consideration when prescribing physical activity and structured exercise for people with disability. It may be more appropriate to have energy, rather than movement, targets when prescribing physical activity for this population.

The impact of gait disability on the calibration of accelerometer output in adults with multiple sclerosis

Accelerometer activity counts have been correlated with energy expenditure during treadmill walking among ambulatory adults with multiple sclerosis (MS). This study examined the effects of gait disability on 1) the association between rates of energy expenditure and accelerometer output in overground walking and 2) the calibration of accelerometer output for quantifying time spent in moderate-to-vigorous physical activity (MVPA) in people with MS. The sample consisted of 24 individuals with MS, of whom 10 reported gait disability based on Patient-Determined Disease Steps (PDDS) scores. The participants undertook three 6-minute periods of overground walking while wearing an accelerometer and a portable metabolic unit (K4b2, Cosmed, Rome, Italy). In the first period of walking, the participants walked at a self-selected, comfortable speed. In the two subsequent walking periods, participants walked at speeds above and below (±0.5 mph) the comfortable walking speed, respectively. Strong linear relationships were observed between rates of accelerometer activity counts and energy expenditure during walking in the overall sample (R(2) = 0.90) and subsamples with (R(2) = 0.88) and without gait disability (R(2) = 0.91). The slope of the relationship was significantly steeper in the subsample with gait disability (β= 0.0049) than in the subsample without gait disability (β= 0.0026). The difference in slopes resulted in a significantly lower cut-point for MVPA (1886 vs. 2717 counts/min) in those with gait disability. These findings provide a metabolic cut-point for quantifying time spent in MVPA in people with MS, both with and without gait disability.

Exercise in multiple sclerosis

Exercise is an intervention that may be used in the management of multiple sclerosis (MS). Certain exercise physiology characteristics are commonly seen among persons with MS, particularly in the more debilitated. Studies have shown that properly prescribed exercise programs can improve modifiable impairments in MS. Exercise is generally safe and well tolerated. General guidelines are available for exercise prescription for the MS population. There are several recommendations that may help improve the quality of future MS exercise trials.

Multiple sclerosis alters the mechanical work performed on the body's center of mass during gait

Patients with multiple sclerosis (MS) have less-coordinated movements of the center of mass resulting in greater mechanical work. The purpose of this study was to quantify the work performed on the body's center of mass by patients with MS. It was hypothesized that patients with MS would perform greater negative work during initial double support and less positive work in terminal double support. Results revealed that patients with MS perform less negative work in single support and early terminal double support and less positive work in the terminal double support period. However, summed over the entire stance phase, patients with MS and healthy controls performed similar amounts of positive and negative work on the body's center of mass. The altered work throughout different periods in the stance phase may be indicative of a failure to capitalize on passive elastic energy mechanisms and increased reliance upon more active work generation to sustain gait.

Accelerometry and its association with objective markers of walking limitations in ambulatory adults with multiple sclerosis

OBJECTIVE

To validate accelerometry based on its correlations with 6-minute walk distance (6MWD) and oxygen cost of walking as objective markers of walking limitations in multiple sclerosis (MS).

DESIGN

Cross-sectional.

SETTING

Laboratory and general community.

PARTICIPANTS

Ambulatory participants with MS (N=26) who resided in the local community.

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

Patient Determined Disease Steps (PDDS) scale and Multiple Sclerosis Walking Scale-12 (MSWS-12); 6-minute walk test while wearing a portable metabolic unit for measuring the 6MWD and oxygen cost of walking; accelerometer during the waking hours of a 7-day period.

RESULTS

The average of total daily movement counts from the accelerometer correlated significantly and strongly with MSWS-12 scores (ρ=-.681, P=.001), PDDS scores (ρ=-.609, P=.001), 6MWD (ρ=.519, P=.003), and oxygen cost of walking (ρ=-.541, P=.002).

CONCLUSIONS

We provide evidence that further supports the validity of accelerometry as a measure of walking limitations in ambulatory persons with MS.

Walking impairment in patients with multiple sclerosis: exercise training as a treatment option

Multiple sclerosis (MS) is a chronic disease of the central nervous system that culminates in the progression of physical and cognitive disability over time. Walking impairment is a ubiquitous feature of MS and a sentinel characteristic of the later or advanced stages of the disease. This paper presents a conceptual rationale along with empirical evidence for exercise training as a rehabilitation approach for managing walking impairment and improving walking function in persons with MS. Conceptually, MS is associated with a decrease in physical activity, which, in turn, can result in deconditioning across multiple domains of physiological functioning. The resulting deconditioning feeds back and further drives physical inactivity until a threshold is reached that likely initiates the progression of walking impairment in MS. Empirically, physical activity and exercise training have been associated with beneficial effects on walking function in persons with MS. This is based on cross-sectional, longitudinal, and experimental research that included diversity in the breadth of measures of walking, persons with MS, and exercise/physical activity characteristics. Of particular importance, future researchers might consider examining the combinatory effects of exercise training plus pharmacological agents on walking mobility in MS. Collectively, exercise training and physical activity might hold significant potential for the management of progressive mobility disability in MS.

Influence of exercise on nutritional requirements

There is no consensus on the best diet for exercise, as many variables influence it. We propose an approach that is based on the total energy expenditure of exercise and the specific macro- and micronutrients used. di Prampero quantified the impact of intensity and duration on the energy cost of exercise. This can be used to determine the total energy needs and the balance of fats and carbohydrates (CHO). There are metabolic differences between sedentary and trained persons, thus the total energy intake to prevent overfeeding of sedentary persons and underfeeding athletes is important. During submaximal sustained exercise, fat oxidation (FO) plays an important role. This role is diminished and CHO's role increases as exercise intensity increases. At super-maximal exercise intensities, anaerobic glycolysis dominates. In the case of protein and micronutrients, specific recommendations are required. We propose that for submaximal exercise, the balance of CHO and fat favors fat for longer exercise and CHO for shorter exercise, while always maintaining the minimal requirements of each (CHO: 40% and fat: 30%). A case for higher protein (above 15%) as well as creatine supplementation for resistance exercise has been proposed. One may also consider increasing bicarbonate intake for exercise that relies on anaerobic glycolysis, whereas there appears to be little support for antioxidant supplementation. Insuring minimal levels of substrate will prevent exercise intolerance, while increasing some components may increase exercise tolerance.

Oxygen cost of treadmill and over-ground walking in mildly disabled persons with multiple sclerosis

Walking impairment is a ubiquitous feature of multiple sclerosis (MS) and the O(2) cost of walking might quantify this dysfunction in mild MS. This paper examined the difference in O(2) cost of walking between persons with MS who have mild disability and healthy controls and the correlation between the O(2) cost of walking and disability. Study 1 included 18 persons with mild MS and 18 controls and indicated that the O(2) cost of walking was significantly higher in MS than controls and that disability was significantly associated with the O(2) cost of slow, moderate, and fast treadmill walking. Study 2 included 24 persons with mild MS and indicated that disability was significantly correlated with O(2) cost of comfortable, fast, and slow over-ground walking. We provide evidence that the O(2) cost of walking is an indicator of walking dysfunction in mildly disabled persons with MS and should be considered in clinical research and practice.

Does an accelerometer accurately measure steps taken under controlled conditions in adults with mild multiple sclerosis?

BACKGROUND

Accurate measurement is required by researchers and clinicians who are interested in the physical activity behavior of individuals with multiple sclerosis (MS). Advances in technology have resulted in an increased number of motion sensors such as pedometers and accelerometers that are worn on the body and that measure bodily movement. Accelerometers are becoming less expensive and more user-friendly, but there is limited evidence regarding the accuracy of measurement in persons with MS.

OBJECTIVE

The present study examined the accuracy of an ActiGraph accelerometer for measuring steps taken during controlled conditions in persons with MS compared with a sample of individuals without MS.

METHODS

The participants were 24 adults with mild MS and 24 adults without MS who undertook three 6-minute periods of walking at 54, 80, and 107 m·min(-1) on a motor-driven treadmill. We measured steps taken through observation and an ActiGraph model 7164 accelerometer worn around the waist above the right hip.

RESULTS

The accelerometer accurately measured steps during moderate (80 m·min(-1)) and fast (107 m·min(-1)) walking in both persons with MS and control subjects. There was a small degree of underestimation of step counts (≈4% error) for the accelerometer during slower walking (54 m·min(-1)) in both persons with MS and control subjects.

CONCLUSIONS

Such findings support the accuracy of a waist worn ActiGraph accelerometer for the measurement of steps in persons with MS and control subjects.

Multiple Sclerosis Walking Scale-12 and oxygen cost of walking

BACKGROUND

The 12-item multiple sclerosis walking scale (MSWS-12) has been validated against self-report and clinical markers, but has not been validated with a physiological marker of locomotor impairment.

OBJECTIVE

This study further validates the MSWS-12 based on its correlation with the oxygen cost (O(2) cost) of walking as a physiological marker of locomotor impairment in persons with multiple sclerosis (MS).

METHODS

Participants (N=24) with MS completed the MSWS-12 and then wore a portable metabolic unit for measuring the O(2) cost of walking during three 6-min walk (6MW) tests. The first 6MW test involved the participant's comfortable walking speed (CWS), whereas the second and third 6MW tests were undertaken above (faster walking speed, FWS) and below (slower walking speed, SWS) the participant's CWS (i.e., +/-5mph CWS).

RESULTS

MSWS-12 scores correlated strongly with O(2) cost of walking during the 6MW tests undertaken at CWS (r=.641, p=.001), FWS (r=.616, p=.001), and SWS (r=.639, p=.001).

INTERPRETATION

We provide evidence that further confirms the validity of the MSWS-12 as a measure of the impact of MS on walking.

Calibration of accelerometer output for ambulatory adults with multiple sclerosis

Motl RW, Snook EM, Agiovlasitis S, Suh Y. Calibration of accelerometer output for ambulatory adults with multiple sclerosis.

OBJECTIVES

To examine the association between the rates of accelerometer activity counts and energy expenditure during walking in persons with multiple sclerosis (MS) versus controls and then to calibrate the output of accelerometers for computing time spent in light, moderate, and vigorous physical activity based on common metabolic equivalent unit categories in persons with MS.

DESIGN

Mixed-model design.

SETTING

Laboratory.

PARTICIPANTS

People with MS (n=24) and people without MS (n=24) who were similar in age, sex, height, and weight.

INTERVENTIONS

The participants undertook three 6-minute periods of walking at 3.2, 4.8, and 6.4km.h(-1) on a motor-driven treadmill.

MAIN OUTCOME MEASURES

Activity counts and energy expenditure were measured with an accelerometer worn on the right hip and open-circuit spirometry, respectively.

RESULTS

The results indicated that (1) persons with MS had greater energy expenditure, but not activity counts, during walking on a treadmill than did controls; (2) there was a strong linear relationship between activity counts and energy expenditure during treadmill walking, but the slope of the relationship was steeper in persons with MS than in controls; and (3) the cut-points for light, moderate, and vigorous physical activity were lower in persons with MS than in controls.

CONCLUSIONS

Such findings provide evidence for a strong linear relationship between activity counts and energy expenditure during walking in persons with MS and cut-points based on counts per minute for quantifying time spent in light, moderate, and vigorous physical activity using accelerometers in this population.

Multiple sclerosis and physical exercise: recommendations for the application of resistance-, endurance- and combined training

This review summarizes the existing knowledge regarding the effects of physical exercise in patients suffering from multiple sclerosis (MS). Furthermore, recommendations are given regarding exercise prescription for MS patients and for future study directions. Previously, MS patients were advised not to participate in physical exercise. During recent years, it has been increasingly acknowledged that exercise benefits MS patients. The requirement for exercise in MS patients is emphasized by their physiological profile, which probably reflects both the effects of the disease per se and the reversible effects of an inactive lifestyle. To date the effects of exercise have only been studied in moderately impaired MS patients with an EDSS score of less than 7. Evidence exists for recommending participation in endurance training at low to moderate intensity, as the existing literature demonstrates that MS patients can both tolerate and benefit from this training modality. Also, resistance training of moderate intensity seems to be well tolerated and to have beneficial effects on MS patients, but the methodological quality of the existing evidence is in general low and the number of studies is limited. Only two studies have evaluated the effects of combined resistance- and endurance training, making solid conclusions regarding this training modality impossible.

Measuring activity patterns using actigraphy in multiple sclerosis

Multiple sclerosis (MS) is a demyelinating disease resulting in impairments in motor and mental performance and restrictions in activities. Self-report instruments are commonly used to measure activity patterns; alternatively, actigraphs can be placed on several parts of the body. The aims of this study were to evaluate the superiority and specificity of actigraph placement (wrist vs. ankle) in subjects with MS and healthy controls and explore the relationship between self-report and objective activity patterns. A total of 19 subjects with definite MS and 10 healthy volunteers wore actigraphs on the non-dominant wrist and ankle for three days while they kept a log to register performed activities every .5 h. Wrist and ankle actigraphs produced similar activity patterns during the most active hours (09:00-20:30 h) (ANOVA, timexlocation interaction: F=.901, df=23, p=.597) in individuals with MS and healthy controls (between subjects factor F=3.275, p=.083). Wrist placement of the actigraphs was better tolerated than ankle placement. Wrist actigraph data corresponded to a higher degree with self-reported activities of the upper limbs in the early afternoon, whereas ankle data seem to reflect better whole body movements in the later afternoon/early evening. Overall, actigraph data correlated moderately with self-reported activity (r=.57 for ankle and r=.59 for wrist). The regression model revealed that self-reported activities explained 44% of the variance in ankle and 50% of wrist data. Wrist and ankle actigraphs produce similar activity patterns in subjects with MS and in healthy controls; however, the placement of actigraphs on the wrist is better tolerated. Ankle actigraphs reflect general movement but underestimate upper body activity. Subjective registration of activity level partly matches with objective actigraph measurement. A combination of both objective and subjective activity registration is recommended to evaluate the physical activity pattern of subjects with MS.

Effect of aerobic training on walking capacity and maximal exercise tolerance in patients with multiple sclerosis: a randomized crossover controlled study

BACKGROUND AND PURPOSE

Physical deconditioning is involved in the impaired exercise tolerance of patients with multiple sclerosis (MS), but data on the effects of aerobic training (AT) in this population are scanty. The purpose of this study was to compare the effects of an 8-week AT program on exercise capacity-in terms of walking capacity and maximum exercise tolerance, as well as its effects on fatigue and health-related quality of life-as compared with neurological rehabilitation (NR) in subjects with MS.

SUBJECTS AND METHODS

Nineteen subjects (14 female, 5 male; mean age [X+/-SD]=41+/-8 years) with mild to moderate disability secondary to MS participated in a randomized crossover controlled study. Eleven subjects (8 female, 3 male; mean age [X+/-SD]=44+/-6 years) completed the study.

RESULTS

After AT, but not NR, the subjects' walking distances and speeds during a self-paced walk were significantly improved, as were their maximum work rate, peak oxygen uptake, and oxygen pulse during cardiopulmonary exercise tests. The increases in peak oxygen uptake and maximum work rate, but not in walking capacity, were significantly higher after AT, as compared with after NR. Additionally, the subjects who were most disabled tended to benefit more from AT. There were no differences between AT and NR in effects on fatigue, and the results showed that AT may have partially affected health-related quality of life.

DISCUSSION AND CONCLUSION

The results suggest that AT is more effective than NR in improving maximum exercise tolerance and walking capacity in people with mild to moderate disability secondary to MS.

Cardiopulmonary and metabolic functions, aerobic capacity, fatigue and quality of life in patients with multiple sclerosis

OBJECTIVES

The objectives of this study were to evaluate cardiopulmonary and metabolic functions in patients with multiple sclerosis (MS) and to clarify the relationship between these functions and neurological deficits, respiratory involvement, fatigue and quality of life.

MATERIALS AND METHODS

Twenty-five patients with MS and 15 healthy controls were included in the study. Cardiopulmonary and metabolic responses to maximum exercise were investigated with an electronically braked arm crank ergometer. A computerized gas analysis system collected and analysed expired gases during exercise.

RESULTS

In the present study, significant respiratory muscle weakness, and decreased aerobic performance and cardiopulmonary and metabolic responses to maximum exercise were determined in patients with MS.

CONCLUSIONS

As respiratory muscle function plays a strong role in aerobic capacity and in most of the cardiopulmonary and metabolic responses to exercise, measurement of respiratory muscle strength and endurance should also be carried out in the MS population.

Treadmill training for individuals with multiple sclerosis: a pilot randomised trial

This pilot study investigated whether 4 weeks of aerobic treadmill training in individuals with multiple sclerosis (MS) improved mobility and reduced fatigue. Individuals with MS were recruited to this prospective, randomised controlled trial. Individuals were assessed at baseline, week 7 and 12 with a 10 metre timed walk, a 2 minute walk, the Rivermead Mobility Index, and the Fatigue Severity Scale. After a pre-assessment familiarisation session and a baseline assessment, individuals were randomly allocated to an initial intervention or delayed intervention group. Treadmill training consisted of 4 weeks of supervised aerobic exercise delivered weeks 3-6 in the immediate group and 8-11 in the delayed group. Of the initial 19 recruits, 16 individuals completed the study. There was a significant difference in walking endurance between the delayed and immediate groups at baseline (p<0.05). On reassessment in week 7, decreases in 10 metre walk time were found in both groups, which was significant in the immediate group (p<0.05). The 2 minute walk distance significantly increased in both groups (p<0.05). In the training group, reassessed at week 12 after training ceased, there was a return towards baseline scores. No significant changes in fatigue scores were found. This study showed that in individuals with MS, aerobic treadmill training is feasible and well tolerated. Walking speed and endurance increased following training with no increase in reported fatigue. Detraining occurred in the period following training. A larger randomised clinical trial is warranted.

Six-minute walk distance as a measure of functional exercise capacity in multiple sclerosis

PURPOSE

We hypothesised that six-minute walk (6MWT) distance of patients with ambulatory multiple sclerosis (MS)would differ from age-matched healthy control subjects. We also investigated the contribution of demographic, physical and physiological factors to impaired functional capacity in MS.

METHOD

Thirty MS patients and 30 healthy subjects participated in this study. Respiratory muscle strength was measured. Pulmonary function test and 6MWT were performed. The Barthel Index (BI) was used to assess activities of daily living, and the Modified Ashworth Scale was used to determine spasticity. Symptomatic fatigue was measured using the Fatigue Severity Scale (FSS).

RESULTS

Pulmonary function and respiratory muscle strength of ambulatory MS patients were significantly lower, and baseline heart rate and fatigue perception were significantly higher than were healthy controls (p < 0.05). MS patients reached a significantly higher exercise heart rate, and walked significantly shorter distance than did healthy subjects (p < 0.05). The BI score, baseline heart rate and FSS score together accounted for 81 percent variance in 6MWT distance of MS patients (p < 0.05).

CONCLUSION

The shorter distance covered during a 6MWT is determined by the limitations in activities of daily living,resting heart rate and subjective symptomatic fatigue in ambulatory patients with MS. Respiratory muscle weakness, lung function and level of neurological impairment do not contribute to impaired functional exercise capacity in these patients.

Exercise and Rehabilitation for Individuals with Multiple Sclerosis

It is the coexistence of physical and cognitive impairments, together with emotional and social issues in a disease with an uncertain course, that makes MS rehabilitation unique and challenging. Inpatient rehabilitation improves functional independence but has only limited success improving the level of neurologic impairment. Benefits are usually not long lasting. Severely disabled people derive equal or more benefit than those who are less disabled, but cognitive problems and ataxia tend to be refractory. There is now good evidence that exercise can improve fitness and function for those with mild MS and helps to maintain function for those with moderate to severe disability. Therapy can be performed over 6 to 15 weeks in outpatient or home-based settings or as a weekly day program lasting several months. Several different forms of exercise have been investigated. For most individuals, aerobic exercise that incorporates a degree of balance training and socialization is recommended. Time constraints, access, impairment level, personal preferences, motivations, and funding sources influence the prescription for exercise and other components of rehabilitation. Just as immunomodulatory drugs must be taken on a continual basis and be adjusted as the disease progresses, so should rehabilitation be viewed as an ongoing process to maintain and restore maximum function and QOL.

Cardiorespiratory response to walk in multiple sclerosis patients

To ascertain whether fatigue perception is linked to exertion dyspnea and/or to an impaired cardiorespiratory response during walk, 11 patients (8 females, age range 21-46 years) with multiple sclerosis (MS) and mild disability underwent the 6-min walk test. Ten healthy subjects (7 females, age range 25-49 years) were studied, as a control group. Patients did not differ from controls in spirometry, lung volumes and respiratory muscle strength. There was a significant difference in walk distance between patients and controls (P<0.001), but not in dyspnea perception. In patients, the walk distance significantly related to disability score (P<0.01), but not to fatigue. Compared to controls, patients had a significant decrease in oxygen pulse during walk (P<0.05) and a significant increase in the ventilatory equivalent of CO2 both at baseline and during walk (P<0.05). The relative contribution of both the tidal volume and of the ratio of inspiratory to total breathing cycle duration to the increase in minute ventilation during walk was significantly less in patients, as compared to controls (P<0.05). We conclude that in MS patients with mild disability, fatigue and exertion dyspnea are different sensations without any link and a peripheral limitation during walk can occur.

Effects of a short-term exercise training program on aerobic fitness, fatigue, health perception and activity level of subjects with multiple sclerosis

Multiple sclerosis (MS) patients of an inpatient rehabilitation program have been randomly assigned to an exercise training (MS-ET) or nontraining group (MS-NI). Before and after 4 weeks of aerobic exercise training, a graded maximal exercise test with measurement of gas exchange and a lung function test was administered to all 26 patients fulfilling the inclusion criteria. Activity level, fatigue and health perception were measured by means of questionnaires. Twenty-six healthy persons served as control group and were matched in respect of age, gender and activity level. Training intervention consisted of 5x30 min sessions per week of bicycle exercise with individualised intensity. Compared with baseline, the MS training group demonstrated a significant rightward placement of the aerobic threshold (AT) (VO2+13%; work rate [WR])+11%), an improvement of health perception (vitality+46%; social interaction+36%), an increase of activity level (+17%) and a tendency to less fatigue. No changes were observed for the MS-NI group and the control groups. Maximal aerobic capacity and lung function were not changed by either training or nontraining in all four groups. Overall compliance to the training program was quite low (65%), whereas incidence of symptom exacerbation by physical activity has been lower than expected (6%).