Exertional rhabdomyolysis , AKA “march rhabdo†occurs in athletic “adventures†or in recruits ( hence the reference to marchingâ€.
Eccentric muscle contraction , which you do on long downhills, overexertion, inadequate conditioning, heat, dehydration and more are factors. In most mild or moderate cases like on Whitney, Bob’s suggestions and time work well. I had it there on one occasion but not the others. But if severe, there are very serious medical complications . For more info, see
Rhabdo