Heat Chamber Horror

We've had a few hot days recently here in Victoria so no better time than now to reflect on how to successfully manage our bodies while exercising or competing in warmer conditions.  I recently dug up an article I wrote for a Tri club magazine about 10 years ago and thought it might provide some fodder for the blog.  The trial sought trained male athletes to be involved in a study of the affects of heat on muscle during exercise, which is relevant  now that we are coming into summer.

First up was a VO2 (http://en.wikipedia.org/wiki/Vo2_max) test on an exercise bike.  During this trial the resistance on the bike increased every three minutes for the first nine minutes and then every minute for the remainder of the trial.  Basically you ride till you drop.  On the surrounding walls of the VUT lab at Footscray where the trial was held were photographs of the who’s who of Australian sport.  The "Oarsome Foursome”, Big Merv Hughes and the Aussie cricket team and the cream of the AFL who had gone before me on the exercise bike.  The researcher measured my CO2 output to also obtained a measure of my maximum oxygen uptake per minute.  This reading is generally proportional to the amount of muscle in your body.  The more muscle, the higher the VO2 reading.

The second trial involved a heat chamber trial at Deakin Uni. I got changed into my cycling gear and had the procedure explained to me.  Next they gave me a fine piece of tubing which they said would help measure my core temperature.  My next comment was something like “You want me to put it where?  Surely you are joking".  No they weren’t!  Next was to put on a heart rate monitor followed by a muscle biopsy of my quadricep with a great big hollow horse needle in to obtain a sample (a bit like sucking a thickshake through a straw).  After the biopsy the temperature of my muscle was taken and then a bung was placed in my arm and a few blood samples were taken.

It was off to the heat chamber and onto the bike, where the temperature was a warm 40 degrees celsius.  The level of resistance was set and I started off comfortably spinning at around 90-95 RPM in time to the techno beats.  Every five minutes an assistant took three samples of blood via the bung in my arm, while another collected my CO2 for two of every five minutes for about the first thirty minutes.  Before too long I was dripping with sweat and doing it hard in the dry heat.  The research assistants were full of support telling me I was doing a great job.  How much longer I thought to myself.  The revs started to slip from 90 to 80 and I tried to pick up the pace again, but it was getting harder to maintain the momentum to keep the pedalling easy.  As the fifty minute mark approached I knew I was near the threshold of my efforts.  The assistants all yelled support, while at the same time gathering around me like vultures waiting for me to die.  After I could not pedal even one more rev, the doctor repeated the muscle biopsy, temperature reading and a few more blood samples.  After being assisted (carried) off the bike, they set about feeding me to replenish my lost reserves – Gatorade, muffins, jelly beans and muesli bars.  Mmmm – almost worth the pain.

A week later the third trial was conducted.  It was identical in all aspects to the first heat chamber trial, with the exception that the temperature was 22 degrees Celsius.  This time I rode for one hundred minutes, exactly double that of my effort in almost twice the temperature.  Another couple of interesting results to come out of the survey were the facts that my muscle temperature and my core body temperature were the same in both trials, so it's clearly muscle temperature which is the key determinant in when the body says no more.

All of the trials involved fasting before the trials and no fluid intake during the trial.  One of the important lessons is to ensure you are properly hydrated when participating in physical activity, especially in the heat and to lessen your expectations in warmer conditions.  While not everyone likes taking on fluid before and during exercise, it's an important part of preparation, so if you are going for a run make it around a park where there are bubblers, take a camel back or some change to buy a drink.  If you're going for a ride take a second water bottle just in case you need it and a great tip for keeping your drink cool is to put your bidon in a wet sock.  Remember your body is like a car radiator and needs to be topped up and it's too late to do anything once it has run dry.

If you've got a tip on  keeping cool during summer exercise, then post it to the comments.