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Are "passive" extension exercises really passive?
1University of Miami School of Medicine, Department of Orthopaedics and Rehabilitation, Coral Gables, FL 33146.
The Journal of Orthopaedic and Sports Physical Therapy
|February 1, 1994
Summary
Extension exercises, often considered passive for back muscles, show significant electromyographic (EMG) activity. These findings suggest that "passive" back extension exercises are not truly inactive for erector spinae muscles.
Area of Science:
- Rehabilitation Medicine
- Biomechanics
- Exercise Physiology
Background:
- Extension exercises are commonly used in back rehabilitation, often presumed to be passive for erector spinae muscles.
- The actual muscle activation during these maneuvers is not fully understood.
Purpose of the Study:
- To quantify electromyographic (EMG) activity in lumbar back extensor muscles during various extension exercises.
- To determine if commonly prescribed "passive" extension exercises are truly inactive.
Main Methods:
- Surface EMG was recorded bilaterally from lower lumbar muscles in 62 pain-free subjects.
- EMG activity was measured during four positions: lying prone, extension in lying prone, standing neutral, and extension in standing.
- Data were analyzed using one-way ANOVA for repeated measures and Tukey's post hoc test.
Main Results:
- EMG activity was significantly greatest during extension in lying prone.
- EMG activity was least when simply lying prone.
- No significant difference in EMG activity was found between the two standing positions.
Conclusions:
- "Passive" back extension exercises are not truly passive, as they elicit significant EMG activity in lumbar back extensor muscles.
- Extension in lying prone generates the highest muscle activation.
- For clinicians prioritizing minimal erector spinae activation, the prone lying position may be more beneficial than active extension exercises.