As a heat wave sweeps across Europe and North America, governments and media are releasing advice to ensure that citizens are informed and can take steps to avoid overheating. For elite athletes who are racing in these hot temperatures, cooling is essential because heat impacts performance. In the men's and women's Tour de Suisse, the extremely hot racing conditions has meant that pre-cooling and active cooling is prevalent, and we take a closer look at the cooling strategies of the world's best teams and cyclists.
Get your ice cubes ready because this year the Tour de Suisse has been hit by the hot weather, we recorded outside temperatures up to 40ºC / 104ºF. Athletes already get hot with sustained physical intensity (including in cooler temperatures) and this increased body heat affects performance. When outside temperatures are extreme, it becomes even harder to keep cool. The body has to work harder to stay cool by circulating blood to the skin for cooling through sweat evaporation which means there is less blood is circulating to deliver oxygen to the muscles so there is a natural drop in power when athletes get hot.
Before the race, it is assumed that the athletes have already completed heat training and conditioned themselves so that their body is capable of performing better when hot to deliver higher power output and sustained intensity. Of course, athletes want to avoid overheating, but fundamentally, keeping as cool as possible is better for racing performance. These are pre-cooling and active cooling strategies spotted at the Tour de Suisse this year that are helping to keep the riders cooler for longer.
Pre-cooling ahead of the race
The idea of pre-cooling is to simply to keep body temperature as cool as possible at the start of the race to delay the inevitable heat. Typically, riders need to warm-up on the trainers before a race start which naturally increases the core body temperature. At the Tour de Suisse, all of the 'strategies' for pre-cooling were used:
• Ice-vests are more popular than ever and provide the obvious effect of cooling the skin and circulating blood. Some riders were also on the starting line awaiting the race start with their cooling vests still on under the hot sun to slow their increase in core body temperature.
• Cool and wet towels are usually dipped in an ice bucket and have an added effect of wetting or saturating the cycling-kit. Aside from the pleasant cooling effect, this cools the skin and adds more moisture to the skin (in addition to sweat) to provides even more cooling from evaporation.
• Icepacks are typically used on the neck and provide the feeling of relief and cooling. While melting ice can deliver more water to the skin and clothing and the 'feeling' of being comfortable is important, the value of icepacks is debatable as the effect of feeling cool from cooling the body on one spot can delay the natural sweating behavior of the body.
• Fans are indispensable, the more air flow, the better the cooling as it expedites sweat evaporation. When the skin and clothing is wet with sweat and moisture, the cooling effect is greater.
• Cool drinks and slushies used in combination with other pre-cooling approaches is often refreshing and can help somewhat to keep the internal body temperature low.
• Staying in the shade for as long as possible... this one is obvious.
• Drenching the body and clothing ahead of the race start adds extra moisture to help cooling via evaporation and at the Tour de Suisse several riders were also opting to be completely drenched from the starting line.
Active cooling during the race
During the race, the cooling strategy is usually planned in advance and includes advice to the riders by the coaches and sports directors, the placement of the drink stations along the route and strategic planning (in combination with other racing factors) to consider break-aways and attacks from predictions of the condition and racing behavior of the team riders and of the competitors.
Most trained riders are aware of their own individual thresholds, the core body temperature is one of these and managing this meaning that using cooling approaches ahead of time is important. As body temperature changes comparatively slowly compared to other variables like power output and heart rate, active cooling needs to be started in advance, particularly as it is more effective to keep cool than to recover when too hot:
• Hydration is obvious for cooling however during a race can be easily forgotten. Cool drinks from the team car can bring relief.
• Water drenching is one of the most effect active cooling approaches. In hotter weather and while riding at faster speed, sweat can evaporate quickly so drenching the head and body with water adds more moisture to trigger the evaporation effect which cools the skin and the circulating blood. During downhills when sweat dries quickly, dousing the body in water repeatedly triggers more cooling from the evaporation.
• Ice and icepacks can provide relief and the melting ice provides more moisture for evaporative cooling.
• Sportswear fabrics has taken big steps in recent years for custom-fit, lightweight, breathable, and aerodynamic performance. Cooling is a factor that can contrast against other performance attributes. For example, a material that is excellent for moisture wicking to draw sweat from the skin may be counter-productive for cooling where moisture retention and evaporation of moisture against the skin beings better cooling for the athlete. For summer races, many of the teams have cycling kit that provides more breathability and wind-cooling.
• Aerodynamics trade-off is one of the dilemmas in cycling as good aerodynamics of the bike, clothing and riding position typically come at a cost of cooling as the airflow to the rider is limited. Depending on the stage and duration, some teams can opt for bikes, cycling clothing and helmets that are better suited.
• Drafting is a highly effective cooling strategy as less power is required by riders who draft. This reduction in power output reduces the amount of heat the body creates and needs to dissipate. In practice, drafting can be used by riders in a breakaway or in a team seeking to control the peloton to ensure each rider has enough recovery. A rider at the front with the highest power output as they are riding against the wind needs to drop back and then draft to recover and avoid their body temperature spiraling too high.