There are three types of sweat glands in the human body. Whilst all play some role in keeping us cool, some do it better than others and for different reasons:
- Eccrine glands aim to regulate the body’s temperature. As we heat up (through exercise or simply because it is hot), our nervous system goes to work to stimulate the eccrine glands to cool us down by releasing sweat. Primarily made up of water and sodium, the fluid coats our skin to create a coolant.
- Apocrine glands are found mainly in the underarm and groin regions. Although our body’s temperature can stimulate these glands, they are largely triggered by stress, anxiety or hormones. The apocrine glands regions are also home to a number of bacteria that metabolise sweat in these areas. This process is how body odour is created – the smell of bacteria dining out on our sweat. Yum.
- Apoeccrine glands have characteristics of both types of glands above. They are larger than eccrine glands, but smaller than apocrine glands. Apoeccrine glands are found in the armpits and perianal region and secrete more sweat than both eccrine and apocrine glands.
In this article, we are going to focus on exercise induced sweat which primarily looks at eccrine glands.
Why do we sweat?
Two major components to our individual sweat rates are our fitness level and weight/surface area.
The heavier an individual is, or the larger their frame, the harder their body needs to work in order to move, jump, or achieve what they set out to achieve. Accordingly, there is also more “size” to cool down.
Equally, a “fit” person will typically start sweating earlier and with less effort because as we become fitter, our body becomes more efficient at regulating our body temperature. The sooner we begin sweating, the sooner we begin to cool down allowing us to perform at a higher intensity for longer.
Size is significant
A study conducted in 2011 for the American Journal of Physiology suggested that sweat rates depend on how much physical work we do, and our surface area in relation to heat production.
It was found that sweat rates depended on heat production which related to how hard our bodies work in order to “move”. Under “normal” conditions (i.e. not scorching temperatures), the amount we sweat depends on how much physical work we are doing, and our physical size. Changes in core temperature and sweat volume are determined by metabolic heat production, body mass, and body surface area.
Those with a greater body mass will typically sweat more because they have greater metabolic processes in action, thus producing more heat.
When we start exercising, most of the calories we burn (energy) generate heat rather than motion. To neutralise that heat, our bodies sweat, creating an evaporative effect that cools our skin.
As our fitness improves (endurance, strength, power etc.), we can work harder for longer. The consequence of this is that we are now capable of generating a lot more heat, and can generate it for longer periods. The body responds by starting the sweating process sooner and with greater volume in order to give us the best chance of keeping our bodies temperature at a safe level.
Greater volumes of local and whole-body sweat are found in individuals with a high aerobic fitness due to greater metabolic heat production and greater need for evaporative measures to cool their system.
A 2010 study published in Experimental Physiology compared sweating rates of fit participants to that of unfit participants and found fit participants not only perspire more, but they also start sweating sooner during exercise. The study concluded that high fitness levels allow us to exercise at a higher intensity, generating more heat, which leads to more sweat.
Interestingly, in less fit individuals, forehead sweat volumes are double that of fitter individuals. In this case, this type of sweating creates greater “wetness” on the skin rather than an efficient glaze, leading to dripping, and reduced sweating efficiency.
Staying cool and hydrated
We wrote an article here on keeping cool during the hot season which lists a few ideas to help stay cool. But otherwise, drink plenty of water, and consider looking into an electrolyte supplement (the Project UNITED mob use Endura and Xtend). If you sweat like a weapon, water may not be enough to keep your systems at their best so an electrolyte replacement supplement may be the ticket. Try to avoid pre-bottled big brand sports drinks if you can help it. They have a tendency to be loaded with sugar or artificial sweeteners, and can be costly if you are using them frequently.