Jeff Nichols (https://www.performancefirstus.com) and Stew Smith (https://www.stewsmithfitness.com) discuss training hard in the heat of the summer and the many thing you should be doing to avoid heat performance issues, heat exhaustion, and heat stroke and even rhabdo and death. 

https://www.military.com/military-fitness/general-fitness/beating-the-summer-heat-work-training-and-play

Check out other videos of combat swimmer stroke, workouts, and other spec ops related training.  See http://www.stewsmithfitness.com for more information about military, law enforcement, special ops, fire fighting training programs.