The Fifth Season is Here: Fire Season
Wildfire smoke is a reality southwest Montana mountain bikers will have to accept.
by Sam Van De Velde, Exercise Physiologist
Local mountain bikers are used to wildfire season, when the skies better resemble downtown LA than southwest Montana. But as conditions become more intense and fires more frequent, we’re stuck with unhealthy air for a longer period of the summer. So, can you still bike? Should you still bike? How hard? And for how long? What are the harmful effects that can occur exercising in wildfire smoke?
Exercise inherently increases the number of inhaled pollutants. Pollutants in the air disrupt the blood-oxygen transport, causing excessive cardiovascular strain. Pollution also increases metabolites and various other physiological responses that directly affect the individual's performance during physical activity. Furthermore, exercising in air-polluted environments might increase the risk of diseases due to an exercise-induced amplification in respiratory uptake, lung deposition, and toxicity of inhaled pollutants.
If there are underlying atherosclerosis or early signs of cardiovascular disease, even fit individual’s pollutants can exacerbate cardiovascular complication as pollutants not only increase cardiovascular strain due to less oxygen transport, but pollutants distribute a systemic and pulmonary inflammation response. Lastly, chronic exposure to pollutants can lead to chronic systemic inflammation that increases chances of atherosclerosis, or hardening of vessel walls.
But is sedentary behavior riskier?
Exercise is still beneficial, and is one of the leading markers to health and longevity. Despite the negative effects of pollutant exposure the heart is a muscle, and if you don’t use it you lose it. Cardiovascular disease is the number one cause of death. Therefore, we don’t want to avoid exercise to the point where we become sedentary, and wildfire smoke is not an excuse to become or remain a couch potato. More importantly be aware of when, how hard, for how long we should be exercising during fire season. Below is a series of tips and tricks to make the appropriate decision on duration, intensity, and general exposure upon mountain biking during fire season.
Tips for Cyclists During Poor Air Quality
No matter what, reduce air pollution exposure during rest and exercise as much as possible. Air pollution does have concrete links to lung disease, heart disease, and mortality—it is bad for us!
Try to reduce poor air quality index with time of exposure, and distance from exposure. There can be a lot of variation with mountains that can trap smog and wind that can also blow smog away. For example, Sypes Canyon could have a high AQI, as smoke is trapped in the Gallatin Valley, where Garnet Mountain might have clearer air
Ozone levels are typically best early in the morning—go get that worm
Download an air-quality app to map out your exercise plans for the week or day
Why does it matter?
When we begin pedaling uphill, our ventilation of oxygen consumption can climb to five times the volume of air in comparison to our oxygen consumption at rest. This means the more particulate in the atmosphere, the greater effect there is on our pulmonary system as demand for oxygen consumption rises.
Therefore, there are two ways to think about exposure to airborne hazards that can damage an athlete’s lungs.
Amount of time exposed
The intensity of the ride
How to consider exposure
Example 1: Intense 60-min ride @ 4.3L per min x 60 min = 194L of oxygen consumption with particular matter
Example 2: 3-hour easy intensity hike @ 2.4L per min x 180 min = 432L of oxygen consumption with particular matter
Sometimes it may be more advantageous to ride faster and harder for a shorter period than “riding easy” but for a longer trail ride.
To ride or not to ride, that is the question
As a competitive cross-country mountain biker and exercise physiologist, I recognize the risk, however I also appreciate the health benefits riding my bike brings to me mentally and physically. Here’s how I decide when to ride.
Good to Moderate, 0-100 AQI: minimal considerations, a good day for an over distance backcountry trail ride or a high intensity interval ride; bikepacking also a go.
Unhealthy for Sensitive Groups, 101-150 AQI: I will use intensity as a tool to limit my exposure. I would consider racing depending on the temperatures. I will keep rides below 90 minutes, with an adequate rest day following. I will take the day off if I can foresee a better quality day in the near forecast. Bike-packing is a no go due to the duration of exposure.
Unhealthy, 151-200 AQI: No go. Train indoors or take a rest day.
Very Unhealthy, 201-300 AQI: Minimal outdoor exposure all together.
As you can see, deciding whether or not to ride on a smoky day is never black and white. As with most things, there are shades of grey and context matters. Below is a good suggestion from Dr. Phil Hess. “Individuals with asthma, chronic lung issues, or cardiovascular disease should be extra cautious. For most of us, it feels terrible inhaling a lot of particulate and dirty air from wildfires. Through the lens of deciding to race or not, we definitely can’t perform our best, but the long-term effects are negligible considering one bout of exercise.”
If you have more questions, would like a one-on-one consultation, or are interested in an indoor training plan for those smoky days, reach out at any time.
—Sam Van de Velde, Exercise Physiologist, svandevelde@lonepeakpt.com