Optimization of Protocols Using Neuromuscular Electrical Stimulation for Paralyzed Lower-Limb Muscles to Increase Energy Expenditure in People With Spinal Cord Injury

Am J Phys Med Rehabil, 2023 · DOI: 10.1097/PHM.0000000000002120 · Published: June 1, 2023

Spinal Cord Injury Neurology Rehabilitation

Simple Explanation

This study investigates if using surface neuromuscular electrical stimulation (NMES) on paralyzed lower-limb muscles can increase energy expenditure in people with spinal cord injury (SCI). The study also looks at whether activating more muscles and adjusting the stimulation pattern (duty cycle) affects this increase. The study found that NMES significantly increased energy expenditure compared to sitting without NMES. The largest increase occurred when more muscles were activated and the rest period between stimulations was shorter. However, the study also found that muscle fatigue increased with more intense NMES protocols. This fatigue could potentially reduce energy expenditure over longer periods. Future studies should focus on optimizing NMES parameters and examining long-term effects on weight management in SCI patients.

Study Duration

Not specified

Participants

9 men with SCI

Evidence Level

Cross-sectional study

Key Findings

1
NMES significantly increases energy expenditure compared to sitting without NMES in individuals with SCI.
2
The greatest increase in energy expenditure was observed when more muscles were activated and the duty cycle had a shorter rest period.
3
Muscle fatigue occurred significantly with more intense NMES protocols, which may lead to decreased energy expenditure during longer protocols.

Research Summary

This cross-sectional study evaluated the effect of surface neuromuscular electrical stimulation (NMES) of paralyzed lower-limb muscles on energy expenditure in individuals with spinal cord injury (SCI). The study examined the impact of the number of activated muscles and duty cycle on potential increases in energy expenditure. The results indicated that energy expenditure during all NMES protocols was significantly higher than without NMES. The highest increase (+51%) was achieved with the protocol that activated more muscles and used a duty cycle with a shorter rest period. However, the study also found a significant decrease in muscle contraction size with longer stimulation time, more muscles activated, or a shorter rest period. The study concludes that NMES can significantly increase energy expenditure in paralyzed lower-limb muscles compared to sitting without NMES, with the most substantial increase occurring with more muscles activated and a shorter rest period. However, muscle fatigue occurred with more intense protocols, which could reduce energy expenditure during longer periods. Future studies are needed to optimize NMES parameters and investigate long-term effects on weight management in SCI.

Practical Implications

Weight Management Strategies

NMES can be a potential strategy for increasing energy expenditure and aiding weight management in individuals with SCI.

Protocol Optimization

Future research should focus on optimizing NMES parameters, such as frequency, intensity, and duty cycle, to maximize energy expenditure and minimize muscle fatigue.

Clinical Application

Clinicians can consider incorporating NMES protocols that activate more lower-limb muscles with shorter rest periods to achieve greater increases in energy expenditure, while monitoring for muscle fatigue.

Study Limitations

1
Small sample size (n = 9)
2
Relatively short NMES protocols (10 minutes)
3
Lack of validity and reliability studies for muscle contraction size and sitting pressure variance measurements

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