Can confirm. Any training regimen needs to be carefully planned with gradual ramp-up as part of conditioning.
I had two platoons of reserve Soldiers training in Florida for a few months in a strenuous physical course. Any physical activity was planned in advance with a gradual buildup in intensity and carefully monitored, and Soldiers were encouraged to eat full meals (“this isnt the time to start a diet”) and hydration was forced. All was going well, until after about five weeks one Soldier started babbling after a routine morning workout, then passed out and had to be rushed to the hospital. He had severe dehydration and rhabdo and spent three days in the hospital. It turns out he had been sneaking out at night to do additional workouts with heavy weights and hadn’t told us (or asked, we would have refused him).
The US Army’s physical training guide:
https://armypubs.army.mil/epubs/DR_pubs/DR_a/ARN30964-FM_7-22-001-WEB-4.pdf
