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VOLUME 5, ISSUE 1 

 2022 

 

RESEARCH ARTICLE 

Michelini A., Sivasambu H., Andrysek J. The short-term effects of rhythmic vibrotactile and auditory biofeedback on the gait of individuals after  

weight-induced asymmetry. Canadian Prosthetics & Orthotics Journal. 2022; Volume 5, Issue 1, No.6. https://doi.org/10.33137/cpoj.v5i1.36223 

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1 

Michelini A., Sivasambu H., Andrysek J. The short-term effects of rhythmic vibrotactile and auditory biofeedback on the gait of individuals after weight-induced 
asymmetry. Canadian Prosthetics & Orthotics Journal. 2022; Volume 5, Issue 1, No.6. https://doi.org/10.33137/cpoj.v5i1.36223 

 

 

 
RESEARCH ARTICLE 

 

THE SHORT-TERM EFFECTS OF RHYTHMIC VIBROTACTILE AND AUDITORY BIOFEEDBACK 

ON THE GAIT OF INDIVIDUALS AFTER WEIGHT-INDUCED ASYMMETRY 

Michelini A.1,2 *, Sivasambu H.1,2, Andrysek J.1,2  
 
1 Institute of Biomedical Engineering, University of Toronto, Toronto, Canada. 
2 Bloorview Research Institute, Holland Bloorview Kids Rehabilitation Hospital, Toronto, Canada. 

 

 

 

 

  

 

 

 

 

 

 

 

 
 

 

 

 

INTRODUCTION   

Spatiotemporal gait asymmetry is a condition commonly 

exhibited in clinical populations with mobility difficulties 

including individuals with lower limb amputation (LLA), 

Parkinson’s disease, and cerebral palsy. Gait asymmetries 

result in atypical  biomechanical  and  walking and  loading  

 

 

 

 

patterns, and over time, can lead to long-term 

musculoskeletal issues such as joint degeneration and 

osteoarthritis.1,2 Excessive gait deviations and asymmetry 

can be attributed to a lack of proper gait training leading to 

the development of poor gait habits.1 However, there are 

limitations to conventional in-person gait training sessions 

with a physiotherapist, such as the cost and accessibility of 

the service.3 Modern approaches and technologies such as 

virtual reality, rehabilitation video games, and biofeedback 

(BFB) systems take advantage of motor learning strategies 

and are promising tools for gait rehabilitation in the clinic 

and at home.4 

 
OPEN  ACCESS Volume 5, Issue 1, Article No.6. 2022 

 

 

Journal Homepage: https://jps.library.utoronto.ca/index.php/cpoj/index 

 

ABSTRACT 

BACKGROUND: Biofeedback (BFB), the practice of providing real-time sensory feedback has been shown 

to improve gait rehabilitation outcomes. BFB training through rhythmic stimulation has the potential to 

improve spatiotemporal gait asymmetries while minimizing cognitive load by encouraging a 

synchronization between the user’s gait cycle and an external rhythm. 

OBJECTIVE: The purpose of this work was to evaluate if rhythmic stimulation can improve the stance time 

symmetry ratio (STSR) and to compare vibrotactile to auditory stimulation. Gait parameters including 

velocity, cadence, stride length, double support time, and step length symmetry, were also examined. 

METHODOLOGY: An experimental rhythmic stimulation system was developed, and twelve healthy adults 

(5 males), age 28.42 ± 10.93 years, were recruited to participate in walking trials. A unilateral ankle weight 

was used to induce a gait asymmetry to simulate asymmetry as commonly exhibited by individuals with 

lower limb amputation and other clinical disorders. Four conditions were evaluated: 1) No ankle weight 

baseline, 2) ankle weight without rhythmic stimulation, 3) ankle weight + rhythmic vibrotactile stimulation 

(RVS) using alternating motors and 4) ankle weight + rhythmic auditory stimulation (RAS) using a single-

tone metronome at the participant’s self-selected cadence. 

FINDINGS: As expected the STSR became significantly more asymmetrical with the ankle weight (i.e. 

induced asymmetry condition). STSR improved significantly with RVS and RAS when compared to the 

ankle weight without rhythmic stimulation. Cadence also significantly improved with RVS and RAS 

compared to ankle weight without rhythmic stimulation. With the exception of double support time, the 

other gait parameters were unchanged from the ankle weight condition. There were no statistically 

significant differences between RVS and RAS. 

CONCLUSION: This study found that rhythmic stimulation can improve the STSR when an asymmetry is 

induced. Moreover, RVS is at least as effective as auditory stimulation in improving STSR in healthy adults 

with an induced gait asymmetry. Future work should be extended to populations with mobility impairments 

and outside of laboratory settings.  

ARTICLE INFO 

Received: March 19, 2021 

Accepted: January 22, 2022 

Published: February 7, 2022 

CITATION 

Michelini A., Sivasambu H., 

Andrysek J. The short-term 

effects of rhythmic vibrotactile 

and auditory biofeedback on the 

gait of individuals after weight-

induced asymmetry. Canadian 

Prosthetics & Orthotics Journal. 

2022; Volume 5, Issue 1, No.6. 

https://doi.org/10.33137/cpoj.v5i

1.36223 

KEYWORDS 

Spatiotemporal Gait Asymmetry, 

Biofeedback, Rehabilitation, 

Entrainment, Amputation, 

Rhythmic Stimulation, Gait 

 

 

* CORRESPONDING AUTHOR 

Jan Andrysek, PhD 
Bloorview Research Institute, Holland Bloorview Kids Rehabilitation 
Hospital, Toronto, Canada. 

E-Mail: jandrysek@hollandbloorview.ca 

ORCID ID: https://orcid.org/0000-0002-4976-1228 

https://doi.org/10.33137/cpoj.v5i1.36223
https://jps.library.utoronto.ca/index.php/cpoj/index
https://doi.org/10.33137/cpoj.v5i1.36223
https://doi.org/10.33137/cpoj.v5i1.36223
mailto:jandrysek@hollandbloorview.ca
https://orcid.org/0000-0002-4976-1228


 

2 

Michelini A., Sivasambu H., Andrysek J. The short-term effects of rhythmic vibrotactile and auditory biofeedback on the gait of individuals after weight-induced 
asymmetry. Canadian Prosthetics & Orthotics Journal. 2022; Volume 5, Issue 1, No.6. https://doi.org/10.33137/cpoj.v5i1.36223 

ISSN: 2561-987X 
RHYTHMIC VIBROTACTILE AND AUDITORY BIOFEEDBACK  

Michelini et al., 2022 CPOJ 

 
BFB is the practice of providing real-time feedback to an 

individual based on collected information from that user.5 

BFB can be used to supplement traditional gait training 

using various modalities – most commonly through visual, 

auditory, and vibrotactile. Auditory and vibrotactile feedback 

modalities are most suited for wearable and field-based 

applications, however, there is no clear consensus on the 

most appropriate modality for gait rehabilitation.5 Both 

modalities are commonly utilized as part of sensory 

augmentation and substitution. Specifically, in the case of 

gait rehabilitation, auditory or tactile stimulation modalities 

indirectly provide information about gait movements and 

events. While both modalities act to augment sensory 

feedback, they do so by utilizing different neural physiology 

and pathways.6,7 This can manifest into unique responses 

or levels of biofeedback effectiveness. 

Rhythmic movement interventions are a form of BFB that 

have been shown to improve automaticity and gait 

regularity.8 Entrainment is the phenomenon whereby two 

out of phase rhythms synchronize.9 The practice of using 

entrainment for gait training has been shown to be 

successful for a variety of populations, where the individual 

will synchronize their gait cycle (heel strike or toe-off times) 

to an external beat or tempo.10 This can be accomplished 

through rhythmic auditory stimulation (RAS). RAS has been 

shown to improve cadence and symmetry and can be 

effective for gait recovery.11 It has also been shown to 

reduce stride time, swing time, and step time variabilities for 

individuals with Parkinson’s disease and following stroke.12 

Further potential benefits include increased cadence and 

gait symmetry.13  

For individuals with LLA, RAS has been shown to decrease 

gait training times.14 Compared to its auditory counterpart, 

the effects of rhythmic vibrotactile stimulation (RVS) are not 

as well understood; however, RVS is a promising modality 

for gait rehabilitation and particularly wearable applications 

since it does not interfere with the auditory system. RVS has 

been shown to improve step length, and cadence in patients 

with Parkinson’s disease using vibration motors at the 

wrist13 and ankle.14  

The overall goal of this study was to evaluate and compare 

the efficacy of vibrotactile and auditory rhythmic stimulation 

to improve the stance time symmetry ratio (STSR) of able-

bodied individuals with induced asymmetries. Increased 

stance time symmetry has been associated with improved 

gait performance and rehabilitation outcomes in certain 

patient groups.15-17 Secondarily, the study examined other 

key gait parameters including velocity, cadence, stride 

length, double support time, and step length symmetry 

associated with rhythmic stimulation.  

 

METHODOLOGY 

System Instrumentation 

A wearable microcontroller-based system was developed to 

provide vibrational stimulation at the user’s preferred 

cadence and target STSR. RVS was delivered using 

two 9 mm vibration motors (Model 307-103-Precision 

Microdrives Ltd, London, United Kingdom) for a duration of 

100 ms. Each vibrating motor was supplied with 3.3 V, 

corresponding to a nominal vibration frequency of 250Hz 

and vibration amplitude of 7.5 G. An Arduino UNO (Arduino, 

Somerville, Massachusetts) was used to control the timing 

of the RVS delivery and was placed on the user’s waist as 

shown in Figure 1 using a Velcro waist strap. The system 

was powered by a single cell 5000 mAH Lithium-ion battery. 

A motor was adhered directly to the skin on each side of the 

user’s lower abdomen as per Crea et al.,18 behind the waist 

strap. Recent work has found that higher frequency 

vibrations (>230 Hz), targeting Ruffini cylinders and 

Pacinian corpuscles skin mechanoreceptors, increase user 

detection accuracy and reduce reaction times following 

vibrotactile stimulation.19,20 RVS alternated between the left 

and right sides using the two motors as described in  

Figure 2a.  

RAS was delivered using a digital metronome (Google, 

Mountain View, California) on a PC speaker loud enough 

such that the participant could hear throughout the gait 

laboratory. The auditory tones were delivered using a 

singular tone for both left and right limbs as described in 

Figure 2b.  

Figure 1: Equipment and Instrumentation for RVS system. A: Set-

up of the BFB system on a participant; B: Microcontroller-based 

Control Unit, including the custom electronic board, and power 

supply; C: Vibrating Unit (motors) located at the lower abdomen. 

(A) (C) 

Microcontroller 

Custom 

Electronic 

Board 

Power Bank  

(5 V, 5 Ah) 

Vibrating 

Motors    

Ankle 
Weight 

(B) 

https://doi.org/10.33137/cpoj.v5i1.36223


 

3 

Michelini A., Sivasambu H., Andrysek J. The short-term effects of rhythmic vibrotactile and auditory biofeedback on the gait of individuals after weight-induced 
asymmetry. Canadian Prosthetics & Orthotics Journal. 2022; Volume 5, Issue 1, No.6. https://doi.org/10.33137/cpoj.v5i1.36223 

ISSN: 2561-987X 
RHYTHMIC VIBROTACTILE AND AUDITORY BIOFEEDBACK  

Michelini et al., 2022 CPOJ 

 
Participants 

A convenience sample of twelve (N = 12) able-bodied adults 

were recruited for this study. Inclusion criteria included: 1) 

above the age of 18 years, 2) English speaking, and 3) 

having no physical or gait-related impairments, ambulation 

difficulties, or neuro-motor compromises. The study was 

approved by the Research Ethics Board at Holland 

Bloorview Hospital, Canada. Informed written consent was 

obtained from each participant before commencing. 

Experimental Setup and Data Processing 

Previous research has shown that when using rhythmic 

cueing to improve gait parameters such as stride length and 

cadence, it is most effective when the provided tempo of the 

stimulation is close to the participant’s natural cadence.21,22 

For this reason, the cadence was determined by having the 

participant walk at a self-selected speed without the ankle 

weight. The tempo of the RVS and RAS was set to the 

identified cadence value at the user’s self-selected baseline 

speed. 

To induce asymmetry of gait parameters an ankle weight of 

2.27 kg was used; an intermediate value to that used in 

other studies (1.95 – 3 kg),23,24 placed on the non-dominant 

leg.25 The ankle weight was placed on the non-dominant leg 

to compound the asymmetric effect. To determine leg 

dominance, the participant was asked which leg they use to 

kick a soccer ball.26 The participant was given five minutes 

to adjust to the added ankle weight as per Smith and 

Martin.23  

Gait data were collected with the Cortex software (Motion 

Analysis Corporation, Santa Rosa, California) using a 

system with 12 cameras, sampled at 200 Hz. Twenty 

retroreflective markers were placed following a modified 

Helen Hayes Lower Extremity Marker: medial and lateral 

ankles, toes, heels, tibias, medial and lateral knees, thighs, 

anterior superior iliac spines, sacral, and right offset.27,28 

When the ankle weight was added, the lateral and medial 

ankle markers were placed on the outside of the ankle 

weight and in line with the unloaded lateral and medial ankle 

markers. The motion capture position data were smoothed 

within the Cortex software applying a Butterworth low pass 

filter with a cut-off frequency of 6 Hz, as per the study by 

Schreiber and Moissenet.29 Gait parameters were 

processed automatically using the Cortex Software. 

Protocol 

Data for each participant were collected during a single two-

hour session. The participant was asked to walk at a self-

selected speed back and forth along an 8 m walkway 

located in a gait laboratory. A single walking trial consisted 

of one pass of the 8 m walkway. Five baseline trials were 

collected. On average, 1-2 full gait cycles were recorded on 

each pass of this walkway. Following the baseline trials, the 

researcher analyzed one of the trials to determine the 

participant’s preferred cadence. The participant was then 

instrumented with the unilateral ankle weight, given 5 

minutes to walk and adjust to the weight, and then provided 

a 5-minute break to avoid fatigue. Next, rhythmic stimulation 

was provided. The order of RVS or RAS trials was 

randomized using simple and balanced randomization 

through a random number generator (1= RVS first, 2 = RAS 

first). The participant was instructed to walk to the tempo of 

the RVS or RAS, with their heel strike occurring at the time 

of the stimulus. Five minutes of practice with the stimulation 

was followed by a 5-minute break. Subsequently, 5 walking 

trials with rhythmic stimulation were collected. This process 

was repeated with the other stimulation modality. 

Outcome Measures 

The primary outcome measure for this experiment was 

stance time symmetry ratio (STSR), calculated using 

Equation 1, where the limb with the unilateral ankle weight 

is considered the loaded limb, while the limb without the 

ankle weight is considered the unloaded limb. STSR was 

used because of its demonstrated ease of interpretation by 

the user and the ability to assess gait control through this 

 

Figure 2: A) Rhythmic Vibrotactile Stimulation Delivery; B) Rhythmic Auditory Stimulation Delivery. Note: HS (Heel Strike) and TO (Toe-

Off) indicate when the user should be in the HS and TO portions of the gait cycle, respectively, if following the rhythmic stimulation. 

0% 50% 
100% 

0% 50% 
100% 

0% 
50% 

0% 50% 
100% 

0% 50% 
100% 

0% 
50% 

A 

B 

https://doi.org/10.33137/cpoj.v5i1.36223


 

4 

Michelini A., Sivasambu H., Andrysek J. The short-term effects of rhythmic vibrotactile and auditory biofeedback on the gait of individuals after weight-induced 
asymmetry. Canadian Prosthetics & Orthotics Journal. 2022; Volume 5, Issue 1, No.6. https://doi.org/10.33137/cpoj.v5i1.36223 

ISSN: 2561-987X 
RHYTHMIC VIBROTACTILE AND AUDITORY BIOFEEDBACK  

Michelini et al., 2022 CPOJ 

 
variable.30 Perfect symmetry is equal to a value of 1, while 

asymmetry is less than or greater than 1. The individual 

spends more time in the stance portion of the gait cycle on 

the unloaded limb if the symmetry ratio is less than 1.  Some 

deviation around the value of 1 is considered normal. For 

example, Patterson et al. found that for healthy participants, 

the mean STSR was 1.02 ± 0.02 with an upper 95% 

confidence interval boundary of 1.05.31  

Secondary outcome measures included cadence, forward 

velocity, double support time, step length symmetry ratio 

(calculated using the same formula as STSR), and stride 

length. 

Equation (1) 

𝑆𝑇𝑆𝑅 =
𝑆𝑡𝑎𝑛𝑐𝑒 𝑇𝑖𝑚𝑒 𝑙𝑜𝑎𝑑𝑒𝑑  𝑙𝑖𝑚𝑏

𝑆𝑡𝑎𝑛𝑐𝑒 𝑇𝑖𝑚𝑒 𝑢𝑛𝑙𝑜𝑎𝑑𝑒𝑑 𝑙𝑖𝑚𝑏

  

 

Statistical Analysis 

Statistical analyses were performed using JMP Pro 

Software (Statistical Discovery, SAS, USA). The data were 

tested for normality using the Shapiro-Wilk W test for each 

set (p<0.05). Using a repeated measures multivariate 

analysis of variance (rMANOVA), the outcome measures 

were compared among baseline, ankle weight without 

rhythmic stimulation, RVS, and RAS. To account for Type I 

error, a Bonferroni Correction was applied to the original α 

value of 0.05. Therefore, the significance level of α = 0.05/6 

= 0.0083 was used for all statistical tests. The order of RVS 

and RAS was applied in the rMANOVA as an effect to 

account for training throughout the experiment. A paired t-

test was applied for post hoc analysis. If p<0.0083, we 

rejected the null hypothesis that: 

𝐻𝑜: 𝜇𝑏𝑎𝑠𝑒𝑙𝑖𝑛𝑒 = 𝜇𝑎𝑛𝑘𝑙𝑒 𝑤𝑒𝑖𝑔ℎ𝑡 𝑏𝑎𝑠𝑒𝑙𝑖𝑛𝑒 = 𝜇𝑅𝑉𝑆 = 𝜇𝑅𝐴𝑆. 

Effect sizes were calculated using partial η2 with effect sizes 

of  0.01, 0.06, and >0.14 considered small, medium, and 

large, respectively. Mauchly’s Test of Sphericity was used 

to test for the assumption of sphericity.32 

RESULTS 

The participant characteristics are shown in Table 1.  

Table 1: Participant Characteristics. 

Variable Range 
Mean ± Standard 

Deviation 

Age (years) 23-61 28.4 ± 10.9  
  Height (cm) 167-183 174.6 ± 4.7  
Weight (kg) 58.5-113 71.6 ± 15.7 

Calculated Cadence 
(steps/min) 

103-118 111.9 ± 4.7  

Sex: M/F M: 5, F: 7 

Ankle Weight Placement: 
Left/Right 

Right: 1, Left: 11 

 

Mauchly’s Test of Sphericity indicated that the assumption 

of sphericity had been violated (p<0.05) for cadence [χ2(5) 

= 21.48, p<0.0001], stride length [χ2(5) = 14.88, p = 0.011], 

velocity [χ2(5) = 14.66, p = 0.012], and step length ratio 

[χ2(5) = 19.81, p = 0.0.0014], therefore degrees of freedom 

were corrected using Greenhouse-Geisser estimates of 

sphericity. The rMANOVA showed significance for STSR 

[F(3,9) = 55.5, p <0.0001], double support time [F(3,9) = 

17.63, p = 0.0004] and cadence [F(1.91, 21.05) = 17.86, 

p<0.0001], while step length ratio [F(1.43, 15.72) = 0.86, 

p = 0.41], stride length [F(1.67,18.42) = 0.99, p = 0.38] and 

velocity [F(1.78,19.56) = 4.45, p = 0.035] were not.  The 

corresponding effect sizes were 0.95, 0.854, 0.731, 0.001, 

0.011 and 0.012, respectively. There was no order effect in 

the experiment. Means and standard deviations for the 4 

conditions and 6 parameters are found in Table 2. Based on 

the post hoc tests, there was a significant decrease in STSR 

from the no ankle weight baseline to ankle weight without 

rhythmic stimulation conditions [t(11) = -11.99, p<0.0001]. 

The total STSR decrease was 0.061 ± 0.018. Significant 

differences were also found between baseline and RVS 

[t(11) = -11.68, p<0.0001], and baseline and RAS conditions 

[t(11) = -13.09, p<0.0001]. There was also a significant 

improvement from ankle weight without rhythmic stimulation 

to RVS condition [t(11) = 4.91, p = 0.005]. Further, there 

were significant differences in two of the secondary 

outcome measures, including cadence, and double support 

time (Table 2). 

Post hoc analysis showed a significant decrease in cadence 

occurred from baseline to ankle weight without rhythmic 

stimulation conditions t(11) = -4.37, p = 0.0011. There was 

also a significant increase in cadence from ankle weight 

without rhythmic stimulation to RVS conditions t(11) = 5.45, 

p = 0.0002, ankle weight without rhythmic stimulation to 

RAS condition t(11) = 5.25, p = 0.0003, and RVS to RAS 

t(11) = 3.01, p = 0.0117. Significant differences were found 

between double support times at baseline and ankle  

weight without rhythmic stimulation condition t(11) = -5.42, 

p = 0.0002, baseline and RVS condition t(11) = -6.17,  

p<0.0001, baseline and RAS t(11) = -7.76, p< 0.0001, ankle 

weight without rhythmic stimulation and RVS t(11) = -3.15, 

p = 0.0093, and ankle weight without rhythmic stimulation 

and RAS t(11) = -4.14, p = 0.0016. 

DISCUSSION  

This study has uniquely compared auditory and vibrotactile 

stimulation and shown that RVS may be at least as effective 

as its auditory counterpart in improving walking symmetry, 

as well as cadence while maintaining other gait parameters 

(with the exception of double support time). This presents 

an important step in the development of wearable 

biofeedback systems to augment the gait rehabilitation of 

individuals with mobility impairments. 

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5 

Michelini A., Sivasambu H., Andrysek J. The short-term effects of rhythmic vibrotactile and auditory biofeedback on the gait of individuals after weight-induced 
asymmetry. Canadian Prosthetics & Orthotics Journal. 2022; Volume 5, Issue 1, No.6. https://doi.org/10.33137/cpoj.v5i1.36223 

ISSN: 2561-987X 
RHYTHMIC VIBROTACTILE AND AUDITORY BIOFEEDBACK  

Michelini et al., 2022 CPOJ 

 

These findings align with previous studies involving both 

clinical and healthy populations.  In this study the addition 

of an ankle weight provided a means to simulate 

asymmetrical gait. Without any form of rhythmic stimulation 

the weight significantly reduced STSR via an elongation of 

step time of the loaded limb.24,25 Rhythmic stimulation was 

then provided resulting in improved gait symmetry. A similar 

effect has also been found in clinical populations, namely 

stroke patients.33-35 

Although biofeedback significantly improved symmetry in 

this study, perfect symmetry was not achieved. The inability 

to achieve a greater change in STSR and/or perfect 

symmetry is likely related to limitations of the person’s 

capabilities; in the case of clinical populations, this may, for 

example, include motor control issues or limited muscle 

strength, associated with the disability. Similarly, the healthy 

individuals in this study were likely not able to fully 

overcome the effects of the ankle weight. Not only may 

perfect symmetry be unachievable in some cases, but it 

may also be undesirable. In the case of someone with a 

physical or biomechanical asymmetry (i.e. contralateral 

limbs of different masses such in the case of a lower-limb 

prosthetic user, or stroke patient with muscle weakness on 

one side), a slightly asymmetrical gait may present a more 

optimal walking pattern (i.e. to decrease metabolic cost or 

increase stability).36 Hence, the application of biofeedback-

based gait training must carefully consider the patient’s 

capabilities as well as rehabilitation goals. 

Both gait velocity and gait symmetry are commonly used to 

measure overall gait performance as indicators for 

community ambulation and level of gait control, 

respectively.31 Robinson and Smidt note that as gait velocity 

increases, so does overall mobility.37 In our previous 

research using corrective biofeedback, symmetry was 

achieved at the cost of decreased walking speed and 

cadence;38 in contrast, this experiment demonstrated 

greater symmetry (using both biofeedback modalities) 

accompanied by a significant increase in cadence, while 

other measured spatiotemporal parameters remained 

unchanged from the baseline condition. The lack of 

significant change in velocity, stride length and step length 

symmetry ratio may be a result of the biofeedback targeting 

temporal rather than spatial aspects of gait. Hence 

vibrotactile rhythmic stimulation, like its auditory 

counterpart, applied in this experiment has the potential to 

improve gait more holistically.   

Both stimulation methods (vibrotactile and auditory) 

produced similar results, and improvements in gait. This 

was not necessarily an expected finding, since the sensory 

systems utilize different receptors, neural pathways and 

processing centers. Sigrist et al. has said that auditory 

feedback is suitable for the perception of temporal 

information, while haptic feedback is appropriate for the 

perception of spatial and temporal information.6 Moreover, 

in everyday life, humans are exposed to auditory and 

vibrotactile rhythmic stimuli differently, hence one might 

expect that responses would differ also. For example, music 

is a common stimulus resulting in entrainment and the 

synchronization to auditory signals.39 Entrainment based on 

somatosensory stimulation on the other hand, is less 

common in the physical world. Hence, one may expect 

auditory stimuli to be more effectively utilized. This study, 

however, suggests that the sensory modality may play a 

minor role, as long as signals are able to be adequately 

sensed.  Further, it may be possible that gait performance 

is more substantially influenced by elements of motor 

control or even perhaps biomechanics (ability of our 

muscles to control the movements to overcome the effects 

of the ankle-weight) rather than the ability to sense and 

process rhythmic stimulation. Future work is needed to 

better elucidate the neurophysiological mechanisms 

involved in the utilization of biofeedback in gait.   

The findings of this experiment may be influenced by 

several factors. Increased double support times were 

exhibited across all conditions in this study compared to 

typical gait of 20%.40 This may be due to slower gait or gait 

Table 2: Gait Parameters Under Different Conditions. 

 
No ankle weight 

baseline 
Ankle weight without 
rhythmic stimulation 

Ankle weight with 
rhythmic vibrotactile 
stimulation (RVS) 

Ankle weight with 
rhythmic auditory 
stimulation (RAS) 

(Mean ± Standard Deviation) 

Stance Time 
Symmetry Ratio 

0.999 ± 0.007†‡ 0.938 ± 0.019*‡ 0.952 ± 0.016*† 0.950 ± 0.014* 

Cadence (steps/minute) 111.9 ± 5.2† 107.9 ± 5.5*‡ 111.7 ± 4.4† 112.5 ± 4.3†‡ 

Step Length 
Symmetry Ratio 

0.998 ± 0.025 0.994 ± 0.055 1.006 ± 0.023 1.009 ± 0.019 

Stride Length (cm) 139.6 ± 11.6 140.8 ± 13.9 142.4 ± 15.9 142.8 ± 15.4 

Velocity (cm/s) 130.1 ± 11.5 126.8 ± 14.9 132.7 ± 16.6 133.9 ± 15.6 

Double Support Time 
(% of the gait cycle) 

32.7 ± 1.7†‡ 31.2 ± 2.1*‡ 30.3 ± 2.6*† 30.1 ± 2.2*† 

 

* Denotes significantly different values than the baseline condition 
† Denotes significantly different values than the ankle weight without rhythmic stimulation condition 
‡ Denotes significantly different values than the RVS condition  
 

 

 

 

 

 

 

 

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6 

Michelini A., Sivasambu H., Andrysek J. The short-term effects of rhythmic vibrotactile and auditory biofeedback on the gait of individuals after weight-induced 
asymmetry. Canadian Prosthetics & Orthotics Journal. 2022; Volume 5, Issue 1, No.6. https://doi.org/10.33137/cpoj.v5i1.36223 

ISSN: 2561-987X 
RHYTHMIC VIBROTACTILE AND AUDITORY BIOFEEDBACK  

Michelini et al., 2022 CPOJ 

 
compensations that were caused by the test conditions. 

Modality selection for providing feedback through sensory 

substitution is a continuously developing field as the 

underlying mechanisms and resulting effectiveness for 

specific applications are uncovered.7 Work performed in the 

field of balance control found varying effectiveness and 

latencies in responding to feedback modalities based on 

age, proposing that decreased residual processing capacity 

may affect one’s ability to respond to cues from feedback 

systems.7,41 In case future research confirms auditory and 

vibrotactile stimulation to produce similar neurophysio-

logical responses, the ultimate decision about which 

modality to use in biofeedback systems may hinge on other 

factors such as cost and ease of implementation. 

Study Limitations 

This study has several limitations. One limitation of this 

study is that the sound from the motors was not controlled 

for in this experiment. One study that used rhythmic haptic 

stimulation had the participants wear headphones with 

white noise so that they would avoid entrainment with the 

sound of the vibrations and external stimuli.42 However, 

self-generated auditory feedback such as footsteps when 

walking is an important factor when controlling spatial and 

temporal parameters,43 therefore headphones with white 

noise were not used to mask the sounds from the 

vibrotactile stimulation in our experiment. Additionally, the 

mass of the ankle weight used for all participants was equal 

regardless of body mass index, leg strength or other factors. 

In future work the ankle weight should be adjusted based 

on the participant’s characteristics to achieve a similarly 

difficult experience for all subjects.  

Opportunities for Future Research 

Future experiments should also collect and analyze 

kinematic data, which would have been useful in identifying 

any further compensatory mechanisms that the individual 

exhibited. Future work should provide more than one gait 

training session and assess the retention values and long-

term efficacy of RVS and RAS. In terms of prototype 

development, testing of the RVS system should be 

conducted outside of controlled settings to better 

characterize aspects related to cognitive loading and 

impacts of environmental factors on the user’s ability to 

effectively use the system.  

Although it was important to first test this system on able-

bodied adults with an induced asymmetry, future work 

should evaluate the effectiveness of RVS and RAS on other 

clinical populations, such as individuals with LLA. With 

clinical populations, other therapy goals must be addressed 

before and during gait training such as range of motion, 

muscle strength, stability, and proprioception. Further, 

studies are needed to inform the patient demographics that 

may benefit from the biofeedback system. Not all patients 

may be able to utilize or appropriately respond to 

biofeedback, and in some cases targeting gait 

improvements may not align with or be a rehabilitation goal.  

CONCLUSION 

This study has shown that both rhythmic vibrational 

stimulation and rhythmic auditory stimulation can effectively 

improve walking asymmetry induced by the addition of an 

ankle weight. In addition to improving stance time symmetry 

ratio, other important aspects of gait such as cadence were 

preserved. Establishing the viability of vibrotactile based 

gait training and BFB systems is an important step in 

developing technologies and feedback modalities for use 

outside of clinical settings where auditory feedback may not 

be appropriate.  

ACKNOWLEDGEMENTS 

The authors wish to thank Firdous Hadj-Moussa for her support in 

reviewing and editing the manuscript. 

DECLARATION OF CONFLICTING 

INTERESTS 

Contents from this manuscript were part of a master’s thesis. The 

authors declared no potential conflicts of interest with respect to the 

research, authorship, and/or publication of this article. 

AUTHOR CONTRIBUTION 

Alexandria Michelini: Conceptualization, methodology, validation, 

formal analysis, investigation, writing original draft, 

writing/review and editing, visualization. 

Harry Sivasambu: Validation, formal analysis, investigation, 

writing/review and editing, visualization. 

Jan Andrysek: Supervision, conceptualization, methodology, 

investigation, writing/review and editing. 

SOURCES OF SUPPORT 

The project was supported by Ontario Graduate Scholarship and 

by NSERC CRD (CRDPJ 491125). 

ETHICAL APPROVAL 

The study was approved by the Research Ethics Board at Holland 

Bloorview Hospital, Canada. Informed written consent was 

obtained from each participant before commencing.  

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