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Phys. Ther. Korea 2022; 29(3): 187-193

Published online August 20, 2022

https://doi.org/10.12674/ptk.2022.29.3.187

© Korean Research Society of Physical Therapy

Immediate Effect of Neuromuscular Electrical Stimulation on Balance and Proprioception During One-leg Standing

Jeongwoo Je , PT, BPT, Woochol Joseph Choi , PT, PhD

Injury Prevention and Biomechanics Laboratory, Department of Physical Therapy, Yonsei University, Wonju, Korea

Correspondence to: Woochol Joseph Choi
E-mail: wcjchoi@yonsei.ac.kr
https://orcid.org/0000-0002-6623-3806

Received: July 4, 2022; Revised: August 2, 2022; Accepted: August 4, 2022

This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Background: Neuromuscular electrical stimulation (NMES) is a physical modality used to activate skeletal muscles for strengthening. While voluntary muscle contraction (VMC) follows the progressive recruitment of motor units in order of size from small to large, NMES-induced muscle contraction occurs in a nonselective and synchronous pattern. Therefore, the outcome of muscle strengthening training using NMES-induced versus voluntary contraction might be different, which might affect balance performance. Objects: We examined how the NMES training affected balance and proprioception.
Methods: Forty-four young adults were randomly assigned to NMES and VMC group. All participants performed one-leg standing on a force plate and sat on the Biodex (Biodex R Corp.) to measure balance and ankle proprioception, respectively. All measures were conducted before and after a training session. In NMES group, electric pads were placed on the tibialis anterior, gastrocnemius, and soleus muscles for 20 minutes. In VMC group, co-contraction of the three muscles was conducted. Outcome variables included mean distance, root mean square distance, total excursion, mean velocity, 95% confidence circle area acquired from the center of pressure data, and absolute error of dorsi/plantarflexion.
Results: None of outcome variables were associated with group (p > 0.35). However, all but plantarflexion error was associated with time (p < 0.02), and the area and mean velocity were 37.0% and 18.6% lower in post than pre in NMES group, respectively, and 48.9% and 16.7% lower in post than pre in VMC group, respectively.
Conclusion: Despite different physiology underlying the NMES-induced versus VMC, both training methods improved balance and ankle joint proprioception.

Keywords: Balance, Biomechanics, Neuromuscular electrical stimulation, One-leg standing, Proprioception

Article

Original Article

Phys. Ther. Korea 2022; 29(3): 187-193

Published online August 20, 2022 https://doi.org/10.12674/ptk.2022.29.3.187

Copyright © Korean Research Society of Physical Therapy.

Immediate Effect of Neuromuscular Electrical Stimulation on Balance and Proprioception During One-leg Standing

Jeongwoo Je , PT, BPT, Woochol Joseph Choi , PT, PhD

Injury Prevention and Biomechanics Laboratory, Department of Physical Therapy, Yonsei University, Wonju, Korea

Correspondence to:Woochol Joseph Choi
E-mail: wcjchoi@yonsei.ac.kr
https://orcid.org/0000-0002-6623-3806

Received: July 4, 2022; Revised: August 2, 2022; Accepted: August 4, 2022

This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Background: Neuromuscular electrical stimulation (NMES) is a physical modality used to activate skeletal muscles for strengthening. While voluntary muscle contraction (VMC) follows the progressive recruitment of motor units in order of size from small to large, NMES-induced muscle contraction occurs in a nonselective and synchronous pattern. Therefore, the outcome of muscle strengthening training using NMES-induced versus voluntary contraction might be different, which might affect balance performance. Objects: We examined how the NMES training affected balance and proprioception.
Methods: Forty-four young adults were randomly assigned to NMES and VMC group. All participants performed one-leg standing on a force plate and sat on the Biodex (Biodex R Corp.) to measure balance and ankle proprioception, respectively. All measures were conducted before and after a training session. In NMES group, electric pads were placed on the tibialis anterior, gastrocnemius, and soleus muscles for 20 minutes. In VMC group, co-contraction of the three muscles was conducted. Outcome variables included mean distance, root mean square distance, total excursion, mean velocity, 95% confidence circle area acquired from the center of pressure data, and absolute error of dorsi/plantarflexion.
Results: None of outcome variables were associated with group (p > 0.35). However, all but plantarflexion error was associated with time (p < 0.02), and the area and mean velocity were 37.0% and 18.6% lower in post than pre in NMES group, respectively, and 48.9% and 16.7% lower in post than pre in VMC group, respectively.
Conclusion: Despite different physiology underlying the NMES-induced versus VMC, both training methods improved balance and ankle joint proprioception.

Keywords: Balance, Biomechanics, Neuromuscular electrical stimulation, One-leg standing, Proprioception

Fig 1.

Figure 1.Schematics of the (a) neuromuscular electrical stimulation intervention, and (b) voluntary muscle contraction intervention.
Physical Therapy Korea 2022; 29: 187-193https://doi.org/10.12674/ptk.2022.29.3.187

Fig 2.

Figure 2.(A) One-leg standing with eyes open or closed. (B) Ankle proprioception measure on the Biodex (Biodex R Corp.).
Physical Therapy Korea 2022; 29: 187-193https://doi.org/10.12674/ptk.2022.29.3.187

Table 1 . Demographic information of participants.

GroupSexHeight (cm)Mass (kg)BMI (kg/m2)Age (y)
VMCMale173.0 ± 6.576.5 ± 14.025.4 ± 3.322.9 ± 2.6
VMCFemale161.6 ± 5.959.3 ± 8.822.7 ± 3.322.2 ± 3.0
NMESMale175.0 ± 5.581.0 ± 19.626.4 ± 6.024.7 ± 2.8
NMESFemale162.1 ± 3.957.4 ± 6.221.9 ± 2.522.4 ± 2.1

Table 2 . Values of outcome variables of balance.

NMESVMCp-value


MaleFemaleMaleFemale




ECEOECEOECEOECEO









PrePostPrePostPrePostPrePostPrePostPrePostPrePostPrePostGroupSexVisionTime
MDISTa
(mm)
17.4 ± 6.815.1 ± 4.17.9 ±
1.4
8.4 ±
2.0
12.3 ± 2.911.4 ± 2.26.8 ±
1.4
6.5 ±
1.1
15.6 ±
5.6
12.8 ±
2.8
8.4 ±
1.8
7.2 ±
1.6
12.8 ±
3.0
12.5 ±
3.2
6.7 ±
1.9
6.9 ±
1.0
0.5520.001*0.000*0.003*
RDISTb
(mm)
19.7 ± 8.116.6 ± 4.78.9 ±
1.6
9.3 ±
2.1
13.8 ± 3.312.7 ±
2.4
7.7 ±
1.5
7.4 ±
1.2
12.6 ±
6.8
14.3 ±
3.1
9.4 ±
2.0
8.1 ±
1.7
14.3 ±
3.4
14.0 ±
3.6
7.6 ±
2.1
7.6 ±
1.2
0.5550.001*0.000*0.002*
MVELOc
(mm/s)
117.7 ± 48.196.0 ± 31.749.5 ± 11.844.2 ± 14.379.8 ± 16.366.1 ±
14.6
32.5 ±
7.9
30.4 ±
8.3
95.9 ± 28.680.4 ± 24.443.2 ±
11.3
40.6 ±
7.3
87.2 ±
19.1
77.0 ±
21.0
37.7 ±
6.5
34.0 ±
7.3
0.5410.000*0.000*0.000*
TOTEXd
(mm)
941.2 ± 385.0529.0 ± 117.1395.7 ± 94.3353.8 ± 114.3638.7 ± 130.1529.0 ±
117.1
259.8 ±
63.0
243.4 ±
66.2
767.2 ±
229.0
643.5 ±
195.4
345.2 ±
90.6
325.0 ±
121.0
697.5 ±
152.4
615.6 ±
168.0
301.9 ±
52.0
271.8 ±
58.5
0.5410.000*0.000*0.000*
AREAe
(cm2)
40.3 ± 40.425.4 ± 17.87.0 ±
2.4
7.6 ±
3.3
17.0 ± 8.714.2 ±
5.5
5.2 ±
2.2
4.9 ±
2.0
35.8 ±
45.4
18.3 ±
9.4
7.7 ±
3.1
5.8 ±
2.2
18.2 ±
9.5
17.5 ±
10.2
5.3 ±
3.5
5.2 ±
1.7
0.7430.012*0.000*0.021*

Table 3 . Values of outcome variables of proprioception with closed eyes.

MeasureNMESVMCp-value



MaleFemaleMaleFemale





PrePostPrePostPrePostPrePostGroupSexTime
Dorsiflexion error (°)2.8 ± 1.92.7 ± 2.24.3 ± 2.02.9 ± 1.73.4 ± 1.82.2 ± 0.93.9 ± 2.12.3 ± 1.70.5790.2090.005*
Plantarflexion error (°)3.1 ± 2.63.8 ± 2.64.7 ± 2.23.5 ± 2.03.3 ± 1.73.8 ± 1.96.7 ± 4.14.4 ± 2.80.3540.0520.051