Personally I love Townsville weather for running, it’s not too cold in the mornings and it rarely rains. Obviously a downside to this the humidity. The average annual humidity is 61% making for some pretty tough training conditions.
Whilst this may come as no surprise but it is significantly more difficult to run in the heat vs the cold. In fact the best running conditions are around to 5-10 degree mark, and for relatively humidity to be low.
The basic physiological basis as to why is it so much harder comes from two main problems, Inability to cool-down and dehydration.
During moderate activity in warm conditions classified as 20°C-30°C you can lose up at 2-3% water, which in itself is enough to significantly reduce exercise performance.
Following is a simplified description of the demands on the body during hot/humid weather. During exercise in the heat the cardiovascular system becomes unable to supply enough blood for both the muscle and blood, you also start to sweat and this loss of water in turn increases the viscosity of the blood and reducing the stroke volume of the heart, leading to a drop in blood pressure. The body considers maintenance of blood pressure more important than muscle cooling so it increases the heart rate to compensate for the drop in cardiac output and the muscle and skin starts to receive less blood. This continues to push the core temperature higher and you start to get inefficiencies with increasing muscle temperature and lactic aid production. A very common cause for premature termination of exercise (before hitting vo2max or energy depilation) is core temperature of around >39 °C
Some good news is that there may be something is “heat” training similar to people who altitude train, studies have seen training at a hotter environment will give you an advantage to those that train in cooler environments under the same working conditions, whilst the exact causes for this advantageous adaptation has yet to be shown conclusively in studies the main suggested improvements are reduced oxygen uptake & blood lactate at a given power output, plasma volume expansion and improved myocardial efficiency.
So whilst doing outdoor training in Townsville’s oppressive heat and humidity is tough, there is benefit in training in the heat, and when cooler weather comes around again, you’ll notice the benefits.
