A number of recent posts have requested information about this as summer approaches and if we can get everybody tuned in, with an increase in understanding the physiological impact of heat, then we can improve performance and safety when racing. (Originally prepared by TrainingBible Coach David Warden)
How many of you have had heat reduce your performance? Age groupers tend to avoid or are infrequently able to train in the heat, a problem since it's difficult to avoid heat in 70.3 and full Ironman events. Once-weekly week-end bricks are insufficient and the cruel irony is that slow age-groupers are more likely to race in heat. Reduced speed and a later wave start can make for a very long day. Heavy athletes are particularly at risk, so since training should simulate racing conditions as much as possible, heat acclimatization should be considered a part of any training plan.
Non-heat acclimatized athletes perform poorly in the heat as there's competition for blood between skin and muscles. There's more blood flowing to the skin surface for cooling and less is delivering oxygen to the muscles which leads to reduced performance. They also tend to have a higher concentration of electrolytes in their sweat, the loss of which can lead to accelerated muscular fatigue and muscle cramping. Also, when exercising in the heat, the body must increase metabolism in order to cool down leading to increased usage of glycogen, increased blood lactate, potentially invalidating ones training zones-a higher heart rate for a given power output.
While you can neither avoid racing in the heat, nor it's consequences, you can increase your rate of sweating by introducing the body to heat before the race. Warden points out that by exercising an hour a day at the anticipated temperature for 5-10 days, accompanied by an equal reduction in intensity (e.g, zone 2 workouts only for first few workouts), that an improved tolerance to heat develops and can last up to 10 days. This could be accomplished while tapering, say from 17 days to 7 days before your race. But, heat acclimatized athletes should not assume lower fluid requirements.
Additional reading can be found in what the US Army recommends www.usariem.army.mil/download/heatacclimatizationguide.pdf and a lengthy but informative piece by sports scientsts at www.csmfoundation.org/GSSI_-_Preparing_Athletes_for_Competition_in_the_Heat.doc - .
This is an important topic that affects us all and an open forum discussion can benefit many.
Again thanks to David Warden for bring this to light.
John H. Post, III, MD
Orthopedic Surgeon
Charlottesville, VA
How many of you have had heat reduce your performance? Age groupers tend to avoid or are infrequently able to train in the heat, a problem since it's difficult to avoid heat in 70.3 and full Ironman events. Once-weekly week-end bricks are insufficient and the cruel irony is that slow age-groupers are more likely to race in heat. Reduced speed and a later wave start can make for a very long day. Heavy athletes are particularly at risk, so since training should simulate racing conditions as much as possible, heat acclimatization should be considered a part of any training plan.
Non-heat acclimatized athletes perform poorly in the heat as there's competition for blood between skin and muscles. There's more blood flowing to the skin surface for cooling and less is delivering oxygen to the muscles which leads to reduced performance. They also tend to have a higher concentration of electrolytes in their sweat, the loss of which can lead to accelerated muscular fatigue and muscle cramping. Also, when exercising in the heat, the body must increase metabolism in order to cool down leading to increased usage of glycogen, increased blood lactate, potentially invalidating ones training zones-a higher heart rate for a given power output.
While you can neither avoid racing in the heat, nor it's consequences, you can increase your rate of sweating by introducing the body to heat before the race. Warden points out that by exercising an hour a day at the anticipated temperature for 5-10 days, accompanied by an equal reduction in intensity (e.g, zone 2 workouts only for first few workouts), that an improved tolerance to heat develops and can last up to 10 days. This could be accomplished while tapering, say from 17 days to 7 days before your race. But, heat acclimatized athletes should not assume lower fluid requirements.
Additional reading can be found in what the US Army recommends www.usariem.army.mil/download/heatacclimatizationguide.pdf and a lengthy but informative piece by sports scientsts at www.csmfoundation.org/GSSI_-_Preparing_Athletes_for_Competition_in_the_Heat.doc - .
This is an important topic that affects us all and an open forum discussion can benefit many.
Again thanks to David Warden for bring this to light.
John H. Post, III, MD
Orthopedic Surgeon
Charlottesville, VA