Electrically Induced Muscle Contractions Influence Bone Density Decline After Spinal Cord Injury

Spine (Phila Pa 1976), 2006 · DOI: 10.1097/01.brs.0000201303.49308.a8 · Published: March 1, 2006

Spinal Cord Injury Neurology Musculoskeletal Medicine

Simple Explanation

After a spinal cord injury, individuals often experience a rapid decline in bone mineral density, especially in paralyzed limbs, due to the lack of mechanical loading typically provided by muscle contractions. This study investigated whether a specific exercise program involving electrically stimulated muscle contractions in the legs could help reduce bone loss in people with spinal cord injuries. The research showed that stimulating muscle contractions can indeed help to preserve bone density, suggesting that this could be a valuable approach to prevent bone fractures and other complications following a spinal cord injury.

Study Duration

3 Years

Participants

6 individuals with complete paralysis

Evidence Level

Longitudinal repeated-measures; within-subject control

Key Findings

1
The percent decline in BMD for the trained tibia (~10%) was significantly less than the untrained tibia (~25%).
2
Trained limb percent decline in BMD remained steady over the first 1.5 years of the study.
3
Bilateral hip and untrained tibia BMD declined significantly over the course of the training.

Research Summary

This study examined the effect of electrically induced muscle contractions on bone mineral density (BMD) decline in individuals with spinal cord injury (SCI). Six individuals with complete paralysis underwent a 3-year unilateral plantar flexor muscle activation program, with the opposite limb serving as a control. The results indicated that compressive loads induced by muscle contractions partially prevent the loss of BMD after SCI, suggesting a potential intervention strategy to mitigate bone loss in paralyzed extremities.

Practical Implications

Rehabilitation Strategy

Electrical stimulation of muscles can be used as a rehabilitation strategy to prevent bone loss after SCI.

Dosage Optimization

Future research should focus on establishing dose-response curves to determine the optimal amount of compressive load needed to prevent bone loss.

Long-Term Bone Health

Maintaining bone integrity through muscle contractions can help individuals with SCI avoid secondary complications such as fractures.

Study Limitations

1
Small sample size, it is difficult to speculate on the reason for the diminution of the training effect after 1.5 years.
2
Future studies need to determine whether or not this loading strategy remains effective indefinitely.
3
Future studies must also determine whether attenuation of BMD decline can persist beyond 3 years of training.

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