Typically you see quad and medial glute spasm occur just as much on the bike as on the run, and in that case, it is usually due to either tight or adhesed external rotators from upper hip immobility. Usually, that type of immobility is traced to a stuck sacroiliac joint, or a gluteus medius section that needs soft tissue work or trigger therapy.

I suppose it’s possible that your run spasm could have been due to training leading up to the race on the bike, or your bike utilization at the race, in which case you could have your SI joint adjusted and do a ton of foam roller work on the external rotators.

However, if this were more of a nutrition issue, I would certainly be looking into: A) potassium (bear in mind that adrenal exhaustion, overtraining or inadequate recovery will cause increased sodium excretion and potassium retention, which can lead to elecrolyte imbalances and cramping); B) magnesium (over 75% of endurance athletes are deficient, and this could be addressed via use of a topical magnesium rubbed into arms and legs pre training/racing, along with 250-500mg magnesium citrate like Natural Calm before bed each night); C) glycogen depletion (unlikely if you were fueled up, but certainly possible).

Hope that helps!

Ben Greenfield