For decreasing muscle spasm during mechanical lumbar traction, the most appropriate force is:

The appropriate force for decreasing muscle spasm during mechanical lumbar traction is based on the principle that optimal traction helps in relieving nerve root compression and reducing muscle tension. Generally, a force of about 25% of body weight is recommended for effectively managing muscle spasms while ensuring enough separation between the vertebral structures.

This percentage is sufficient to create a therapeutic effect on the lumbar spine by helping to decompress the spinal discs and joints, facilitating blood flow, and promoting relaxation of the muscles. At this level of traction, the goal is to achieve muscle relaxation and relief from pain without causing excessive discomfort or adverse effects.

Lighter forces, such as 10% or 15% of body weight, may not provide adequate traction to effectively address muscle spasms, while heavier traction at 50% of body weight can potentially cause discomfort and may be less effective due to the increase in resistance and tension experienced during treatment. Thus, using around 25% of body weight is the most commonly accepted and effective choice for therapeutic lumbar traction in the context of muscle spasms.