The start of the warm-weather cycling season can be exciting, but also dangerous if, in your rush to enjoy the sun on your Lycra-clad back, you don’t take proper sun-care precautions.
Our body temperature is normally about 37.0oC. In the heat, our body’s main defences include opening our skin blood vessels to release heat through conduction and convection, or else sweating and evaporating heat away from our bodies. If that doesn’t happen, then our core temperature will rise, eventually running into the danger of exertional heat illnesses like heat exhaustion or heat stroke.
Almost every system in your body can experience problems from being too hot. Your heart is under greater stress because it is trying to send blood out to both the muscles for exercise and the skin for heat dissipation. In the past decade, we have also seen that your brain’s ability to recruit muscles, the blood supply to your brain, and even gut function can be seriously impaired at high body temperatures.
So is riding in hot weather as bad as it sounds? The general scientific consensus is that, while you have to be careful, it’s not always a bad thing. The benefit of cycling is that the high windspeeds at even moderate cycling pace generate convective heat flow, so the body is able to dissipate a great amount of heat. This is compared to the much lower speeds found in running used in most scientific studies discussing the dangers of the heat.
UPF or “ultraviolet protection factor” is the rating system used for apparel. It indicates how effectively fabrics shield skin from ultraviolet rays or UV. The higher the UPF number, the greater degree of UV protection a garment offers. UPF gauges a fabric’s effectiveness against ultraviolet radiation from the sun, or UV light. The UPF rating on clothing indicates what fraction of the sun’s ultraviolet rays can penetrate the fabric. A jersey with a UPF of 50, for example, allows just 1/50th of the sun’s UV radiation to reach the skin.
SPF or “sun protection factor”, is the rating system used for sunscreen. An SPF number pertains to a sunscreen’s effectiveness against the sunburn-causing segment of ultraviolet radiation or sunlight. Theoretically, the SPF number indicates how long you can stay in the sun before your skin reddens.
The most important thing is to always wear sunscreen, with at least SPF 30 or above. Sunscreens that contain zinc oxide or titanium dioxide are the most effective for blocking and reflecting UV rays. According to skincancer.org, SPF 30 blocks nearly 97 percent of UVB rays. The efficacy of the sunscreen tapers off around SPF 50, so it is not necessary to apply sunscreen with a SPF higher than 50.
But figuring out which sunscreen works best for you is a process of trial and error. Broad-spectrum coverage sunscreens are ideal, as they cover both UVA rays (which cause aging) and UVB rays (which cause burns). Once you’ve found the one that works for you, apply it consistently when cycling outdoors.
Sunscreen should be reapplied at least every two hours. Trying a quick-absorbing gel formula or a waxy stick sunscreen that will stay put and not run into your eyes and mouth while you ride may be a good option.