In response to an enquiry: “Jumping on trampoline and have muscle spasm in leg.”
Muscle spasms may occur while jumping on the trampoline, while running, while sleeping, while walking, while sitting, and even while standing.
One rather common complaint of writers who sit for long periods writing is inner thigh muscle spasm while sitting. One likely cause is the long period of the sitting posture and bad circulation.
Cold bedrooms and cold legs while sleeping are often the cause of leg muscle spasms in the early morning or in the middle of the night.
Muscle spasms during exercise are mostly expressions of muscle fatigue. Rapidly repeating muscle contractions may serve several purposes: to pump more oxygen and blood to the muscles internally; to autonomically “reboot” the muscles; to autonomically indicate muscle fatigue.