Individuals with multiple sclerosis (MS) exhibit gait impairments characterized by reduced walking speed, gait asymmetry, and instability contributing to increased fall risk [1–3]. Maintaining walking stability requires complex, multi-faceted neurophysiological processes that rely, in part, on the integration of sensory information regarding an individual’s movements and relationship to the surrounding environment [4]. Impaired sensory input and integration in persons with MS are suspected to cause compromised compensatory postural movements, both in anticipation of goal-directed voluntary actions and in response to perturbations [2, 5]. People with MS not only receive sensory information at a slower rate [6], but also experience impaired processing of sensory feedback [7] contributing to their gait dysfunction and fall risk [8, 9].

Axial loadingweightlifting

PDDS = Patient Determined Disease Steps, MSWS-12 = Multiple Sclerosis Walking Scale, MFIS = Modified Fatigue Impact Scale, FES-I = Falls Efficacy Scale International

Research reported in this publication was supported by the National Institute of General Medical Sciences (NIGMS) of the National Institutes of Health (NIH) under Award Number P20GM135007: Vermont Center for Cardiovascular and Brain Health.

This study provided preliminary evidence that non-specific axial loads of varying weights appear to improve certain gait parameters. As such, this modality may offer mobility benefit and serve as an accessible home-based intervention alternative aimed at improving walking in individuals with MS.

Within the control group, significantly faster cadence and gait speed were found from 0%PRE to 2%, to 5%, and to 0%POST as well as from 4% to 0%POST vest weights (table 3). Double support time significantly increased from 2% to 4% and to 5%, while significantly decreasing from 4% to 0%POST and from 5% to 0%POST. The control group also exhibited significantly faster turn velocity from 0%PRE to 0%POST.

Data were analyzed using SPSS Statistics 25 software [International Business Machines (IBM), Chicago, IL, USA]. Sample demographic characteristics and descriptive details of each outcome measure were derived and presented as mean ± SD or as proportions (%). After meeting assumptions for parametric statistics, a 2 (group) × 5 (weighted vest) multivariate analysis of variance (MANOVA) was performed to determine any significant differences between groups (MS and healthy) and across weighted vests (0%PRE, 2%, 4%, 5%, 0%POST) for each gait variable. Post-hoc analysis involved pairwise comparisons with adjustment for multiple comparisons using the Tukey’s test. Additionally, correlations between MS-specific variables and gait parameters were examined and, given the small sample size, paired t-tests and corresponding effect sizes were utilized to determine if significant within-group differences existed across weighted vests for the MS and control groups, separately. Significance was set at p < 0.05.

The results of this study, while promising, must be considered in light of several limitations. While gait impairments have been empirically associated with falls in people with MS, it is not possible to determine whether the changes observed in the present study are sufficient enough to prevent falling. Prospective research must be conducted to determine the magnitude of gait changes necessary to decrease fall risk. Additionally, participants were instructed to walk at a comfortable walking speed throughout the trials. As fast-paced walking speeds have been shown to challenge participants with minimal disability more than self-selected speeds have [40], it is plausible that the lack of statistical significance found in some gait parameters across weighted vests could be reflective of our walking protocol. Research assessing the effects of weighted vests on face-paced walking may accentuate differing effects on gait parameters and turning. Additionally, future research employing weighted vests may help explain the specific mechanisms underlying gait changes and facilitate the development of more targeted walking and fall prevention interventions.

Participants wore an adjustable vest which had pockets along the lower edge of both the front and back (see figure 1). Axial load was applied by placing ½ pound cylindrical weights in the individual vest pockets, with the weight evenly distributed at the front and back, left and right sides.

Send correspondences to: Dr. Susan Kasser, PhD, Department of Rehabilitation and Movement Science, 106 Carrigan Drive, University of Vermont, Burlington, 05405 USA, Susan.Kasser@med.uvm.edu

Axial loadingbody

Due to the small convenience sample, results of this study may not be representative of the general population of people with MS. The participants in this sample were middle aged, had mild to moderate gait impairment, and most had only moderate concerns about falling. These characteristics have been shown to affect gait control and may have affected the magnitude of the effect or the movement techniques participants used in response to axial loading. Further research that involves a more diverse sample is warranted. Furthermore, due to the small sample size and low statistical power, repeated measures analysis was not possible. Larger studies are needed to conduct stronger statistical analyses and further examine the impact of differently weighted vest conditions on walking and turning in people with MS.

Perceived ambulation disability was assessed with the Multiple Sclerosis Walking Scale-12 (MSWS-12) [22]. Participants rated on a five-point scale (1 = no impact, 5 = extreme impact) the impact MS has on their ability to walk under different situations. The Falls Efficacy Scale - International (FES-I) [23] was used to assess the participant’s concerns about falling when performing seven activities of daily living. Fear of falling was reported on a four-point scale (from “1 = not concerned” to “4 = very concerned”) for each activity. The FES-I has been found predictive of fall risk in those with MS [24]. The effect of perceived fatigue on performance of various daily activities was assessed using the Modified Fatigue Impact Scale (MFIS) [25], with 21 items scored on a scale of 0 (never) to 4 (almost always). This scale has been shown to be valid and associate with balance deficits and predict falls in individuals with MS [26].

The two-way MANOVA revealed a significant main effect of group (F (6,100) = 14.74, p = .000; Pillai’s Trace = .47; partial eta squared = .47) on the combined gait variables. When considered separately and adjusting for multiple comparisons, double-limb support time, gait speed, stride length, and turn velocity were statistically significant between groups (table 2). There were no between group main effects for cadence or turn duration. Results also showed no significant main effect of weighted vest (F (24,412) = .19, p = 1.00; Pillai’s Trace = .04; partial eta squared = .01) or interaction effect between group and weighted vest conditions (F (24,412) = .16, p = 1.00; Pillai’s Trace = .04; partial eta squared = .01).

Unlike with walking, there was no significant effect of any weighted vest on turn duration or velocity in the MS group. While turn velocity did significantly increase from pre- to post-weight vest in the control group, it is unclear why this was not the case for participants with MS. It may be that the weighted vests impacted the quality of the turn (i.e., using a step or spin strategy) rather than the temporal nature of turning, especially as turn strategy differs with changing gait parameters [39].

Axial loadingmedical

A convenience sample of twelve participants with MS were recruited through advertisement. Inclusion criteria included having clinically-diagnosed MS, self-reporting a score of 0 to 4 on the Patient Determined Disease Steps (PDDS) scale [21], and acknowledging the absence of disease exacerbation in the previous month. A comparison group of eleven age and gender matched healthy individuals were recruited through word of mouth and required to be neuro-typical and without a diagnosis that might contribute to imbalance.

This study investigated the acute effects of non-specific axial loading on gait velocity and quality during forward walking and turning in individuals with MS. Given previous research on axial loading, we hypothesized that wearing weighted vests would improve specific gait parameters as well as turning metrics, especially in those with MS. Developing a more detailed understanding of these immediate effects on walking can facilitate the development of targeted interventions aimed at improving gait control in this group.

Axial loadingspine

Sensory integration can be manipulated to improve balance and mobility in persons with MS [10]. Interventions that include somatosensory training have demonstrated improvements in functioning [11] and postural stability in those with greater impairment [12, 13]. One sensory modulation technique involves adding weight to the torso. Balance-based torso weighting – an axial loading technique that applies strategically-placed weights to the trunk to alter the center of mass – has been shown to improve postural stability in quiet stance, tandem standing, and dynamic balance and mobility in persons with MS [14–16]. Much of this research, however, has focused on postural control while stationary or when assessed with clinical measures. It remains unclear how torso weighting specifically effects gait metrics and walking quality. Only one study to date has evaluated the effects of balance-based torso weighting on gait parameters in individuals with MS. Gorgas and colleagues [17] found, when weighted, participants with MS had significantly increased velocity and cadence and decreased time in double-limb support, suggestive of improved gait stability. However, given the significant association between turning and falls [18], additional research should examine forward walking along with changing directions to better understand the potential value of torso weighting on mobility.

Axial loadingwrist

People with MS commonly present with impaired sensory integration that contributes to greater mobility challenges and increased fall risk [2, 8, 31]. Interventions to improve gait through sensory modulation, specifically balance-based torso weighting, have been shown effective [14–16]. The present study extends this research by demonstrating that non-specific axial loading significantly improves cadence and gait speed in both persons with and without MS. These findings are noteworthy given improved gait parameters correlate with reduced falls in people with MS [32].

The use of non-specific axial loading – a loading technique that evenly distributes a percentage of the participant’s body weight across the torso – is another strategy shown to increase strength in older adults with no negative effects on fall risk indices [19, 20]. Studies examining this intervention technique in persons with MS are limited. Non-specific axial loading differs from balance-based torso weighting in that it does not require clinically-based quantitative movement analysis for determination of ideal weight placement. As a result, this type of torso weighting may serve as a more simplistic and accessible intervention technique for individuals with MS and, if shown effective, enhance their capacity to engage in independent therapeutic activities at home. Widener and colleagues [16] found that non-specific axial loading in ambulatory persons with MS improved walking speed, although they did not examine the impact of loading on other fall-predictive spatiotemporal gait parameters.

Within the MS group, paired t-tests indicated significantly increased cadence from 0%PRE to 2%, to 4% and to 0%POST weighted vests respectively (table 3). There were also significantly increased gait speeds from 0%PRE to 2% and from 0%PRE to 0%POST weighted vest conditions. From 0%PRE to the 0%POST, cadence and gait speed increased by 3.5% and 6.5% respectively. While not significant, there was shorter time spent in double support from vest weight 2% to 5% and from 5% to 0%POST and longer stride lengths from 0%PRE to 2%, with moderate to large effect sizes of .66, .63, and .62, respectively [30].

Axial loadingexamples

Participants ranged in age from 44 to 75 years and the majority were female. For those with MS, the mean time since diagnosis was 22.6 years with 83% presenting moderate ambulation disability (PDDS 2–4) and reporting moderate to high concerns about falling [29] (table 1). For the MS group, a significant inverse association was found between perceived fatigue and gait speed (r = −.59) in the 2% weighted vest trial only. Falls efficacy was significantly and inversely correlated with cadence (r = −.65, −.69, −.75), with gait speed (r = −.61, −.60, −.58), and with turn velocity (r = −.59, −.57, −.61) at 0% Pre, 2% and 0% post weight vests respectively. There were no significant associations found between perceived walking disability and any gait variable at any vest weight.

More importantly, the results of this study are in accordance with the existing literature on balance-based torso weighting in MS. We found that, with 2% body weight loads, improved gait speed and cadence were observed. While not significant, we also found a large effect of non-specific axial loading on double support time (.66 and.63 for 2% to 5% and 5% to 0%POST respectively) and on stride length (.62 for 0%PRE to 2%). Given that the magnitude of effect is less influenced by sample size [30], these findings offer further support for the benefit of weighted vests. Previous research has shown that increased sensory feedback to people with MS may facilitate postural control and motor responses by increasing the number of signals to the central nervous system [10, 11]. It has been proposed that adding weight to the torso might increase proprioceptive information by adding resistance and joint compression during movement or by enhancing sensory input through tactile signals from the vest [35]. This may have, in part, also been true for the participants in our study, yet we neglected to see improved gait performance with increasing vest weight, especially in the 5% condition. It is possible that the greater loads did not offer enhanced sensory benefits and that the lighter 0% and 2% conditions were sufficient for enhancing sensory input. It may also be that improvement in gait could have occurred due to attentional focus. Research has shown that stability can be affected by the direction of attention placed on a task [36]. Applying an axial load may have caused participants to more intentionally direct their attention on their walking, thereby improving performance, and that increased vest weight was not necessary to further focus their attention. Previous research has also shown that perceived stability is a significant moderator of fall risk [37]. Although speculative, the perception of gait control caused by the initial axial load of 2% may have increased the participants’ feelings of stability while walking with increased vest weight offering no additional benefit.

Secure .gov websites use HTTPS A lock ( Lock Locked padlock icon ) or https:// means you've safely connected to the .gov website. Share sensitive information only on official, secure websites.

The observed gait improvements may also be explained by the study design. Regardless that weighted vests were randomized to control for order effects, the time between the first non-weighted condition and the last non-weighted condition may have allowed participants to physiologically warm-up. Increased temperature, blood flow to muscle, and neurological potentiation resulting from movement in the earlier trials may have led to the improvement of gait parameters observed in this last trial independent of the axial load condition [38].

Axial loadingexercises

All key personnel involved with the study completed Human Subjects Training through the Research Protections Office of their institution and the institution’s Committee on Human Research in the Medical Sciences reviewed and approved the study protocol and related documents. Eligibility of participants was determined through telephone screening and informed consent was obtained prior to data collection.

As expected and observed in previous research [33], there were significant differences between groups. Compared to healthy controls, participants with MS exhibited a greater percentage of the gait cycle in double-limb support, slower gait speed and cadence, and smaller stride length. However, there was no significant effect of weighted vest between groups on any gait or turning parameter, similar to other research on turning metrics in people with and without MS [34].

Despite these limitations, the results of this study contribute foundational data that support the potential use of axial loading in gait interventions for people with MS. Still, more needs to be determined about the scope and duration of this approach. The current study showed that the effects of axial loading persisted after the load was removed in some gait parameters. Additional research can help to determine how long these observed effects on gait last once the load is removed as well as elucidate vest weight percentages to achieve an optimal dose-response. It will also be important to assure that increased axial loads do not inadvertently and negatively impact gait stability and further predispose individuals with MS to greater fall risk.

A significant between groups main effect was found for group (F (6,100) = 14.74, p = .000) in multiple gait parameters (p < 0.05), although no significant main effect was found for weighted vest. Within group analyses indicated significantly increased cadence and gait speed across varying weighted vests for both MS and control groups (p < 0>05). Increased vest weight from 0%PRE to 2% also had large effect on shortening double support time and increasing stride length in the MS group.

Publisher's Disclaimer: This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

Despite uncertainty regarding the exact mechanisms, employing body-worn motion sensors to collect movement data allowed for the detection of subtle changes in gait measures shown to be predictive of falls and not otherwise captured in many clinical tests. One important finding of this study was that non-specific axial loads of varying weights did not appear to have a detrimental impact on gait in this sample. Indeed, the observed impact of the weighted vest conditions appeared to improve certain gait parameters. This finding is noteworthy as weighted vests have been successfully used in home-based programs with older adults to improve strength and functional performance [19] and may offer the same versatility and benefit for adults with MS. Unlike balance-based torso weighting, non-specific axial loading does not require prior gait analysis by a clinician to determine specific weight placements. Additionally, this modality is of low cost and can be integrated into daily free-living physical activity at home. As such, this technique may serve as a more generalizable and accessible intervention alternative aimed at improving walking in individuals with MS.

Axial loadinginjury

Official websites use .gov A .gov website belongs to an official government organization in the United States.

Participants walked back and forth for two continuous minutes, turning at each end of a standard 25-foot distance. Given the exploratory nature of the study and unknown consequences of weighted vests on fall risk, participants were instructed to “walk with purpose” to encourage a self-selected pace that was neither slow nor fast. Each participant completed five trials, with brief rest breaks given between. Each trial was completed while wearing the weighted vest at a different percentage of the participant’s body weight. A vest containing 0% of the participant’s body weight was used for trials one and five (referred to as the 0%PRE and 0%POST vests respectively). The inclusion of a 0% weighted vest after the 4 proceeding trials allowed insight into persistence of axial loading effects. Trials two through four were a randomized order of vest weights containing 2%, 4%, and 5% of the participant’s body weight to minimize order effects. Vest loads were chosen to fall within body weight percentages previously found safe in people with MS [28] and effective for improving gait stability in older adults [19].

Twelve participants with MS and eleven age- and gender-matched healthy controls participated in a cross-sectional study. All participants completed five trials of continuous walking with turns wearing weighted vests at 0%, 2%, 4%, 5%, and then 0% of their body weight. Gait parameters were measured using wireless inertial sensors. A 2 (group) × 5 (vest weight) multivariate analysis of variance (MANOVA) was performed to determine any significant differences between groups and across weighted vests for each gait variable. Post-hoc analysis and paired t-tests with corresponding effect sizes were also conducted.

Spatiotemporal parameters of gait were collected using four Opal wireless inertial sensors (ADPM Inc., Portland, OR, USA), one on each foot, the sternum, and the lumbar spine. Instrumented walking using wireless sensors has been found to offer sensitive, objective, and reliable gait assessment in adults with MS [27]. Data from the OPAL sensors was collected wirelessly at 128 Hz onto a laptop computer. Algorithms within the APDM Mobility Lab software automatically generated specific spatial and temporal gait variable, including gait speed, double-limb support, stride length, turn duration and velocity, and cadence.

Impaired sensory integration is heavily involved in gait control and accentuates fall risk in individuals with multiple sclerosis (MS). While axial loading has been found beneficial, little is known about the effect of non-specific axial loads on gait parameters and mobility tasks in those with MS. Research Question: What are the effects of non-specific axial loading via weighted vests on walking and turning in those with MS.