When running throughout the summer months, there is always an evident difference in the way my body responds to physical exercise - as I am sure is the case for many others. At the beginning of my running journey, I was always that person to wear too many layers for my sessions. No matter how many times I rapidly warmed up within the first mile, I still continued to insist I needed the jacket or pair of gloves that frankly were not always necessary.
Given I now try and wear as fewer layers as I can, it got me thinking about how warm conditions and general over-heating can actually impact our running performance. Personally, I notice a real difference in my running if I am at a comfortable temperature compared to melting under my jacket. Many of my PBs have been achieved when appropriately dressed for how my body will be feeling mid-run rather than when I first step out of the door.
After much thought, I decided to look into the area more and find out how warmer conditions do impact running performance and how these effects can be limited.
How do warmer conditions impact my body?
Partaking in continual exercise within warmer environmental conditions puts physiological strain, often referred to as heat strain, on our thermoregulatory system. Thermoregulation is our bodies process of working to keep our core temperature within certain acceptable boundaries, even when external temperatures show extreme fluctuation. In essence, the mechanisms work to maintain our bodies state of equilibrium.
Models of thermoregulation have suggested that there are critical temperatures that, once reached, can cause our cardiovascular and metabolic systems to overload and function inadequately. Often during exercise, this results in accelerated onset of fatigue. In terms of why this overload occurs, studies have shown that there becomes an enhanced competition for attention within our cardiac system. Our bodies develop a need for increased skin circulation and heat dissipation in order to attempt to cool down, alongside the already demanding metabolic requirements of the muscles that are working during exercise. Therefore, a redistribution of blood flow occurs from the muscles to the skin, reducing the oxygen supply to our muscle tissue and consequently creating feelings of fatigue for the athlete.
How is my running performance subsequently effected?
As discussed, these warmer environmental conditions cause increased strain on our bodies which can result in a clear reduction in exercise performance due to earlier fatigue. Although the optimal temperature for maximal mean speed may vary between runners, studies have shown performance to be detrimentally affected by hot environments when compared with cooler temperatures.
In example, one large study compared data from results of six of the largest marathon races across Europe and America between 2001 and 2010. These results spanned both men and women of all different running abilities. Air temperature was found to have the biggest influence on human racing performance above all other environmental parameters tested, with the findings that our running speed decreases when temperature goes above optimal levels.
Alongside faster rates of fatigue, our levels of water loss due to increased sweating are thought to also play a key role in this reduction in performance. One of my previous posts covers the importance of hydration during exercise in more depth, however a loss of water during exercise can reduce our ability to tolerate the added heat strain. Expectedly, levels of sweat loss were found to be two times higher for athletes running in warm, humid conditions compared with colder conditions. Of these athletes, their worst recorded performances occurred when the highest amount of water had been lost, suggesting a clear correlation between the two.
How can I combat the effects of a warmer environment?
In terms of attempting to cool the body as we run, research suggests there are certain prime spots that will offer more benefit than others. For example, our face is an area of high thermosensitivity meaning that cooling down our face results in a two to five times greater reduction in thermal discomfort than cooling other regions of our body like our limbs or torso. Essentially spots that are closer to our thermoregulatory centre, located in the hypothalamus in the brain, are optimal for cooling due to this proximity.
The act of cooling our body during exercise, such as cooling down our neck or face with cold towels, works by masking the extent of the heat strain we are experiencing. During self-paced exercises, a network of feedback and feed-forward systems regard the physiological state of our bodies in order to regulate whether the task can be completed within ones manageable limits. This network has been further described in the Central Governor Model as a central nervous system mechanism, that without we could exert ourselves to the point of causing serious bodily damage.
Cooling techniques essentially work by deceiving these systems and allowing the athlete to push further whilst exercising in warm conditions. However, it is suggested that there is a limit to how far our central governing system can be deceived before uncovering the true strain being experienced. This ensures we do not push ourselves to point of catastrophic failure during physical exertion. Therefore it can be concluded that our efforts to combat the impact of warmer conditions on our running performance will only work so far and some negative effects should always be expected, particularly with highly strenuous activity.
Thinking in less biological terms, ensuring you do not over dress for the weather can help provide some relief from heat strain. My personal rule of thumb is that temperatures of 10 degrees Celsius or higher usually require minimal kit, even if it feels a little chilly when starting out. Exceptions to this can be dependent on the wind or the sun, since both of these can significantly alter how the temperature feels. Ultimately this is quite a personal preference and something which needs to be trialled and tested on your runs to achieve the optimal solution for your performance.
And of course, as well as methods to keep cooler, hydration is always an effective tool to combat some effects of a hotter environment. Ensuring to pre-load and consume a good amount of liquids the day before a long or strenuous run is good practice. This heightens your blood plasma levels and makes sure your body enters the strenuous physical activity in a good place. Alongside this, taking in fluid during your session is also advised. This doesn't mean consuming vast amount of water in one go, but a good gulp every 15 to 20 minutes will help to keep dehydration at bay.
Have you experienced the impact of warmer conditions on your running performance, perhaps during a particular event? How did it make you feel? Let me know in the comments.