Health&Nutrition

Body Work: Lab Rat

September 30, 2011
By Mihira Lakshman

When I arrived at Ian MacLean’s studio dressed in racing attire, I was prepared for a painful, but necessary experience - a process that I hoped would yield useful training tools. I’ve been a serious runner for about 15 years, but I had never tested my VO2 max. Since I recently started using a heart rate monitor, the value was especially important.

“Even for elite athletes who are experienced and think they know what’s going on - a heart rate monitor is great,” says MacLean, who runs ImFit.ca, a personal coaching service and VO2 max testing lab in Milton, Ont. “But if you don’t really know what that heart rate means, you’re kind of shooting blankly.”

Without a baseline knowledge of an athlete’s maximum heart rate and VO2 max - the amount of oxygen your body can deliver to its muscles during maximum effort - it’s tough to accurately determine training zones.

VO2 max is a common term tossed around in running circles, a key determinant of your speed in middle- and long-distance races. The mark is primarily based on genetics, although it can be trained somewhat. American distance legend Steve Prefontaine had one of the highest ratings for a runner at 84.4 ml/kg/min (cross-country skier Bjorn Daehlie’s 96 is the highest ever recorded VO2 max). In running, VO2 max-pace is somewhere around the speed of a 3K or 5K race.

It’s important, however, not to get hung up on that single number, MacLean says. A VO2 max test provides so much more than a mere rating of your lungs and heart. The test also provides useful data, which pinpoints your heart rate for the five different training zones of varying intensities.

Most of us have grown accustomed to using shortcuts to figure out how hard to push ourselves in a given workout. A subjective rate-of-perceived-exertion scale can help determine intensity levels for the five different training zones, from the slow-aerobic zone 1 to high-intense anaerobic zone 5. There are also shortcuts to find certain measures such as 220 minus your age for maximum heart rate, or plugging a recent 5K race time into a formula to predict your VO2 max. None of those calculations are particularly accurate, MacLean says.

That’s why he recommends going to a testing lab once or twice each season. You’ll not only get your VO2 max and maximum heart rate readings, you’ll also receive two other, and perhaps more vital, training tools: aerobic endurance base, the intensity (zone 2) that your body uses fat as its primary source of fuel; and anaerobic threshold (zones  4), the intensity at which the body can no longer buffer the lactic acid produced in the muscles. “I see people spend thousands of dollars on bikes and shoes and equipment. None of that is any good if you don’t go to the core, which is the engine driving all of that.”

A VO2 Max test costs around $100-160 and takes about 30 minutes. You strap a heart rate monitor around your chest and put on a mask, which has a tube connected to a machine, measuring oxygen intake and carbon dioxide output as you run on a treadmill. Starting out slow, the pace and the incline gradually increases until you reach your breaking point. That’s when you hold the pace as long as you can, reaching your VO2 max, before you stop. The breath-gas data is cross-referenced with heart rate information, determining your aerobic endurance base, anaerobic threshold and maximum heart rate, pinpointing your various training zones.

For runners who aren’t in their best shape, just starting out or coming off a break, they should focus on improving their aerobic endurance base, which unlike VO2 max, can change dramatically over just a few months, MacLean says. Training the body to use fat as a main source of fuel at higher intensities is one of the keys to getting fit. The anaerobic threshold, the effort you could hold for a race lasting about an hour, is another important measure and highly trainable; the best endurance athletes have an anaerobic threshold (also called lactate threshold) that is close to VO2 max.

There are varying methods on how to improve VO2 max: running lots of mileage at 70 per cent of VO2 max effort has been widely regarded as the staple for most distance runners. But a recent study in the Strength and Conditioning Journal suggests that high-intensity interval training may be even more effective. The short bursts of speed training are also likely to improve running economy. Lactate threshold also improved with high-intensity interval training, which the athletes supplemented with gym-based strength and power exercises.

MacLean says arming yourself with the most information possible allows you to train smarter, usually more effective than working out to exhaustion. “I was seeing people training like elite athletes and blowing up, getting injured, just not achieving the results.”