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Muscle cramps in early season football
Cramping in early season football... Just some things to think about that is in the literature on the subject.
1) Is the origin central or peripheral?
a. Central: hyper-excitability of motor neurons at the spinal level. The central inhibitory mechanisms for muscle contraction are suppressed at the same time that excitatory activity is increased due to physical exertion. As a result, a sustained involuntary muscle contraction is generated.
b. Peripheral: spontaneous discharge from the terminal branches of motor nerves. Neuromuscular junctions become hyper-excitable either due to physical or electrolyte changes (or both) resulting in EAMC.
2) Is it dehydration / electrolyte disturbance or fatigue?
a. Dehydration / e-lyte: Whole-body exchangeable sodium deficit develops through sweat loss and as a result the extracellular fluid space becomes contracted. In extracellular space, loss of intravascular volume causes shift from interstitial space to intravascular space further contracting interstitial volume. Contracted interstitial volume "affects nerves" leading to hyper-excitability.
b. Fatigue: Prolonged muscle work results in fatigue and decreased Golgi tendon organ inhibition and increased muscle spindle afferent activity (excitatory) directed at the alpha motor neuron. There are also inhibitory interneurons at the spinal level that might also be suppressed. As a result, you get increased alpha motor neuron activity which leads to cramping.
I think all of these have influence on the development of EAMC. I think it's really interesting that we see cramping more in early season and more in games than practice. At first glance, it seems to make sense (it's hotter, so more sweat loss) and the players work harder during a game (more fatigue). But, they're also more "keyed-up" during a game (especially early in the season or in big games).