In the last blog I mentioned that I would cover why I was able to ride within my lactate threshold heart rate range for two hours and forty-five minutes. That’s not possible – is it?
Recapping some of the altitude specifics, the mainstay of my training over the summer was directed at doing mountain bike races between 8 and 11 hours long and at altitudes between 9,000 and 12,600 feet. I live atroughly 5,000 feet. The September race where I accumulated near three hours at lactate threshold intensity was at altitudes between 3,000 and 6,000 feet.
I’ve written a couple of two-part columns that will give you background of altitude affects on training and racing. The first one is “Altitude Training for Athletic Success” and the second one is “Acclimating to Altitude”. From the columns, a couple of key points:
- Heart rate increases in response to higher altitudes – but you cannot maintain the same speed or power output for that given heart rate at increased altitude. This means that lactate threshold heart rate at increased altitude is lower than your home base.
- For a given speed or power output at a lower-than-your-home-base altitude, the corresponding heart rate will be lower. (Assuming temperature and humidity conditions are similar.)
To know my actual heart rate training zones for all ofthe corresponding altitudes where I raced this summer, I would need to do a test at each location. Since that is logistically not possible for me, I use the same data collection zones for all altitudes and adjust accordingly – I raced according to my rating of perceived exertion (RPE) for the lower altitude event. This means the data for my race at a lower altitude is not really all within an accurate lactate threshold zone. So no, I didn’t spend near three hours at lactate threshold.
Also recall within the altitude columns that you can produce higher speeds and more power output at lower altitudes. (The reason why the Olympians living in Colorado Springs train with supplemental oxygen sources for sea level racing.)
Sans actual power data, I believe I did not have the training to tolerate the power outputs I was generating at the lower altitude race. If the neuromuscular and metabolic systems have not been trained for the speed and power outputs (duration and intensity) possible at lower altitudes, then I believe there is a possibility of cramping.
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