My friends in St. Pete expect me to return in top shape after a couple of months at altitude. But it didn’t really happen last year, my first extended adventure riding at seven, eight, nine thousand feet and above. In fact, when I first returned I was exhausted after a relatively easy ride. The Florida air felt like a brick wall, or at least a gel I had to plow through. It took about a week to get back normal sea level riding.
So I decided to research the issue as I returned to the hills this month. When I started with a few Google search terms, most of what I found was what you would expect. At altitude your heart beats faster. (I also learned that blood pressure increases, though it returns to normal after a few weeks.)
Yet, I’ve noticed when I ride at altitude my heart rate rarely reaches beyond 145 beats per minute (bpm) for sustained efforts. (My max heart rate is about 175 bpm.) One hundred fifty beats per minute feels like I would not explode so much as fall over as my legs crumbled and I gasp for air. Even at a heart rate of 125 bpm, my breathing is fast.
Turns out that may be normal. At extremely high altitudes, researchers found that maximal heart rate decreases as much as 30 bpm. While your resting heart rate is faster, and climbing stairs can put you out of breath, you can’t get the ticker pumping as fast during hard exercise.
That seems logical because at altitude, the thin air makes it more difficult to get the oxygen you need to work hard. The heart simply doesn’t have much to work with.
But heart rate is less important since I bought a power meter. I brought it with me to the mountains. But again, at certain power levels I felt I was working harder than I do at sea level in St. Pete. Additional research led me to several articles that suggested that power levels need to be adjusted downward to coincide with the grater exertion you experience in thin air.
The most widely cited study suggested a formula: Percentage of power held at altitude = -1.12(altitude in km)^2 – 1.90(altitude in km) + 99.9. For example, at an altitude of 2.286 km (a little lower than where I live), power zones need to be about 89.7% of what they are at sea level. My functional threshold power (FTP) would drop from 210 watts to 188 watts, and the zones based on the FTP by the same percentage.
But training at lower power levels has consequences, according to exercise physiologists Ben Griffin and Michael Chiovitti.
The issue here is that the cyclist may in fact de-train due to never actually training at the physiological level of their [anaerobic threshold]. So when this cyclist returns to sea-level after altitude exposure and tries to ride the AT @ 300W it is going to feel extraordinarily hard as they have never actually pushed 300W since prior to going to altitude.
Maybe this is why I was exhausted the first week back in St. Pete last year.
I also found that “altitude training” is not the simply a weeks-long vacation in the mountains riding your bike. There are three basic varieties of altitude training:
- Train high, live high, which is what I do and what I think most pro teams do.
- Train high, live low, which literally means ride your bike at altitudes and then come down from on high to spend the rest of your day.
- Train low, live high, the exact opposite of #2 and a seemingly the preferred method these days.
The idea behind train high and live low is that training at altitude increases red blood cells, or the amount of hemoglobin, but you recover better at lower levels. Train low, live high advocates say simply living at altitude increases your red blood cells but you must train at higher power outputs. More on the three methods here.
Few of us can live high and train low or vice versa. Even those of us who can spend time at altitude must make a commitment as it takes at least three to four weeks to get any benefit from altitude training. Pro racer Michael Rogers says it takes at least a week to acclimate. Virtually his entire first week was easy (for him) riding.
But given that living and riding at 7,000 feet and above as I do here for a few months may actually hurt me when I return to sea level, what training methods can mitigate the loss of power (in spite of increase red blood cells)? Acclaimed trainer Joe Friel has a couple of strategies. The first is shorter intervals with longer recovery periods.
Something on the order of work intervals of two minutes or less followed by two minutes or more of recovery intervals will allow you keep power and pace high. The intensity of these two-minute-or-shorter work intervals needs to be above anaerobic/lactate/functional threshold. Ten to thirty minutes of total high intensity time within a workout, depending on the intensity, your fitness and your purpose, is probably about all you need two to three times a week.
Secondly, Friel says, is to give yourself a break and return to lower levels to recover your sea legs.
At altitude there is a loss of muscular fitness since the workouts can’t be as intense as at sea level. Coming back down for a few days (perhaps as much as two weeks) allows this muscular fitness to be re-established by higher-intensity training.
I can’t do that, so I’ll need to pay the price when I get back to my flat land habitat. So, St. Pete friends, don’t expect much. Riding the hills may not be all that it’s cracked up to be. But it sure is pretty!