Impact of Heat on Fitness

Every year in the UAE the ‘dreaded’ summer comes round. Training peaks feedback becomes weather related and the race to winter begins.

It can be a really difficult time for training, it can also be a great time for training. How you approach the heat will define how you deal with it and ultimately how consistent you remain with your program. 

Some simply chose to stay away from the heat, indoor running, riding and swimming and the comfort of an air-cooled gym. This is fine and certainly any key intense sessions should be done in controlled and cooled conditions, but are you missing out not exposing yourself to the heat?

Exercise in hot conditions places the body under greater physical stress compared to the same intensity of exercise in cooler conditions, that is a fact. A consequence of this fact is performance in the hot conditions is impaired, however, as we know, if we recover properly from stress (training) we develop greater fitness. Remember, exercise breaks down muscle tissue and recovery enables it to be built back up, this is the underpinning mechanism of building fitness. So by increasing stress further through exercising in hot conditions, we can actually gain fitness from it. 

This might not be making sense to you if you have experienced slowly melting into the tarmac of Al Qudra, or wobbling slowly down the beach track wondering why you’re seeing double, but if you think about the timeline of the Dubai race season, and when most of the PB’s occur its usually Dec, Jan and Feb time. A reason for this is that training sub maximally in hot conditions has been shown to increase Vo2 max, enhance cooling capabilities, increase blood plasma volume, a stabilised fluid balance and resting cardiac response. All this means you have a great fitness boost as you head into the critical ‘race build’ through Sept, Oct and Nov. That boost in fitness means a higher training load and training stress tolerance. Those who remained indoors, won’t get this affect as fast because they will have to go through the adaptive phase while the outsiders will be cherishing the cooler climate.

So if you’re an indoor athlete in the summer months, it might be worth considering some heat adaptation. Here are some key points to remember when heading back outside.

  • Stay at sub max intensities. Keep your work rate at 90% or less of threshold HR, pace or power. Basically Do everything at 10% less than you normally would.
  • Lower your temp immediately post exercise. Iced slushies or smoothies are a great way to do this and should be consumed as close to finishing the session as possible.
  • Weight yourself before and after sessions, the weight diff is your fluid loss. 1kg = 1L, replace fluid loss by 1.5 times and include electrolytes.
  • Short term adaptations (7 - 10 days) are rapid, don't give up after 2 - 3 sessions, stick with it to see quick benefits.
  • Long term adaptations kick in after 10 - 14 days, this is when you will notice performance increasing in cooler conditions and resting metrics (pulse, HRV, lower core temp) start to show.

For those who are exercising outside in the summer already, consider the below to help you get the most from the hot months.

  • Know your sweat rate, you may have done it at the beginning of summer but as you adapt further and get better at cooling you will sweat more so be conscious of that.
  • Don't neglect the indoors completely. It is often wise to do your hard (vo2 max/ zone 5 / maximal sprints) indoors if you can. That way you are maximising your anaerobic system which is one area of the bodies physiology that doesn’t improve in the heat.
  • Be aware that for each day out of the heat, the rate of decay is up to 2.5% per day. So if you have spent a few days indoors, be ready for the first day back outside to feel hot!
  • You don't get better at retaining electrolytes, you should always be replacing your electrolytes in hot conditions. Sodium being the most important one. Just water in the heat isn’t enough and you will be seriously impacting your fluid balance, recovery and sleep if you don’t replace what you lose. As sweat rate increases, so will electrolyte loss. 

So that’s it, maybe its time to stop complaining about the Dubai summer and embrace it!? The InnerFight Endurance team certainly does, it isn’t easy but stick to the 10% less rule, replace your fluid loss and electrolytes, eat frozen açai post session and reap the rewards come cooler months. 

By: Coach Tom Walker, Endurance Coach