The purpose of this blog is to explore the impact that climate (particularly temperature, humidity, and radiation) can have on your distance running performance. Knowing how to train for a specific climate OR choosing an ideal race based on climate can help you achieve your goal time at your goal event. It is our hope that by the end of this blog, you understand how heat stress can impact your race day performance and how to adjust your training to maximize performance and minimize risk.
Adaptations to training and considerations for racing
It is possible to improve your racing results in both the heat and the cold by training in the heat. Short-term heat exposure (minimum 6 runs in 2 weeks) will result in physiological adaptations such as expansion of blood volume through increased plasma volume and improvement in sweating/heat loss strategies. In cold or temperate environments, this is capable of facilitating performance gains of a few percent (1-3%). Don’t forget to train smart in the summer and see the results at your next race!
For racing, the temperature should be at its optimum
Running a PB in a race depends heavily on the climate (especially for marathons). Numerous studies have shown that advanced recreational runners should run at a temperature of ~6 degrees Celsius during a marathon (3 hours) and elite runners should run at a temperature of ~3 degrees Celsius during a marathon (2 hours 10 minutes). Since elite athletes race at a higher percentage of their VO2 Max, which means more aerobic metabolism and higher cellular heat production, cooler conditions are important.
In hotter conditions, how will your performance change? Exercise Physiologist Matthew Ely and his team (2007) have discovered that elite Marathon runners (2h 10min) racing in 10-15 deg C will add 1-2min (up to 1.5%), whereas advanced marathon runners (3h) racing in 10-15 deg C will add 4-8min (up to 4.2%), with time losses increasing as race day temperatures rise.
Enter your event, goal time, and anticipated race day temperature into the calculator to see how heat may affect your performance.
The effects of solar radiation
It has also been shown that high levels of solar radiation negatively affect race day performance in addition to high temperatures and humidity (Otani et al. 2016).
To prolong your time to exhaustion, consider covering up some skin if your race will be in full sunlight (i.e. not early in the morning).
Race travel
Training is feasible all year round in Scotland’s climate, which is ideal for distance runners. Many European or further afield cities will experience significant differences in training temperatures between summer and winter. It is common for athletes to train in heat over 30 degrees at 5.30pm in the summer, while it is only 10 degrees at the same time in the winter. Although the body’s physiology at the cellular level is similar, it has a completely different way of cooling itself (primarily by rerouting blood flow to the skin). Your body will deal with heat stress differently on race day depending on whether you trained in the summer or winter. Every year, we see the London Marathon in April where most of the training has taken place in Winter compared to the Loch Ness Marathon where most the training takes place in summer. Training through the summer presents the body with regular heat stress and allows for significant adaptation in blood plasma volume. When you have trained in the heat, through summer, then run in cooler climates, this allows this extra blood to be directed to the muscles. Extra blood increases the oxygen availability, which in part should increase performance. It seems to be easier to achieve a personal best when training through the summer into a cooler marathon.
It is also the case when the race day temperature may be the same but the training block completed in the cold has less benefits than one in the heat.
Physiorun Guidelines for training in the heat
Successful outcomes are based on three mainstays. Volume (high), anaerobic threshold (high) and training days missed (low). The heat can affect the last of these mainstays. Heat training is all relative. If you are used to living in a hot country or region , then these conditions have a minimal effect. However, if you aren’t use to the heat, it will have a more significant effect on your training.
In summary the further from your normal training temperatures the more conservative you would have to be with the training / intensity.
High Intensity Training
With HIT training the easiest way to accomodate for the heat is to keep the same volume of time to be spent at a high level, but reduce the intensity (pace) of the workout. The body is stuck with a conundrum with sending blood to the skin to cool it down or to the working skeletal muscles, it can’t do both. By reducing the intensity you will avoid higher risk of injury and allow the body to adapt to the heat, as more adaptation takes place the pace can increase. The drop in pace could be as low as 10s per kilometer and allows you to have an oxygen reserve that you can use during exercise.
Low Intensity Training
If you are looking to do a long slow run in the heat the recommendation is the opposite of the above. Reduce the volume (duration) of the run but vary the intensity to sit on the slower side of normal into the recovery pace side. If you run at a steady speed it will feel more like a tempo session , whilst it may feel ok at the time this can cause stress that will need to be recovered from, more than a normal session.
The effect on the sessions lateral on in the week will have a knock on effect, the best session is the one you can adequately recover from.
When looking at reducing your run volume, beginner to recreational runners should be cautious about running for >1h in hot conditions (remember that hot is a relative term compared to what you usually training in), whilst advanced runners should be cautious about running for >1h 30min. If you are in a building phase of your training (i.e. your goal event is still a while away), then it’s highly recommended sticking to these volume limits. Cutting a long run or easy run marginally short and respecting the conditions will ensure you don’t over stress your body and end up missing whole sessions down the track. If you are into a specific phase of your training (i.e. your goal race in less than 3-4 weeks away) and the run is a race-specific preparation run, then you are best not to tinker with the run. Aim to complete it as planned on a later date when the conditions are more favourable (the specifics of which should be discussed with your coach). This allows the specific aims of the session to be achieved and to give you the necessary information to strategically plan for your goal race.
Summary
I trust you now have a greater understanding as to how you can ensure your race selection provides you with the best opportunity to beat your best as well as how you can adjust your training when faced with an increased relative training temperature. Thank you for reading and hopefully the greater understanding of the heat intensity can aid your reasoning going forward.
James
(Resource @frontrunnersports – running in the heat)