Which statement best describes how neuromuscular factors influence range of motion?

• A. Decreased tone leads to hypermobility, increased tone leads to restricted ROM.
• B. Increased tone always increases ROM.
• C. Muscle mass has no effect on ROM.
• D. Tone only affects balance, not ROM.

Answer: (A)

Neuromuscular tone sets how much resistance a muscle offers to being stretched. When tone is high, muscles stay stiff and resist lengthening, so a joint’s range of motion becomes more limited. When tone is low, muscles are lax and offer less resistance, which can allow greater movement and, in some cases, hypermobility if the joint isn’t well stabilized. ROM is shaped by how the nervous system regulates muscle activation in addition to the passive properties of tissues, so tone directly influences how far a joint can move. The other statements don’t fit because higher tone doesn’t increase ROM, muscle mass can affect ROM through bulk and tension, and tone influences ROM beyond balance alone.