Some sort of contraption is covering my nose and mouth, and various cords are attached to my body. I start to breath heavily. No, I’m not enduring some form of torture; in fact, it’s fun. I’m voluntarily undergoing a VO2 test, which is analyzing how efficient my body uses oxygen to break down fuel into energy.

Colleen Conners-Pace, from the Tahoe Center for Exercise and Sports Performance in Truckee, calmly stares at the computer and dishes out encouragement as she slowly increases the steepness and speed on the treadmill. As my heart rate increases and I gasp for breath, she gives me good news: ‘You are a good fat burner.’ This is great because I am addicted to aerobic exercise, and efficiently burning up all that delicious fat I am eating is a necessary thing. It’s also confirmation of a well known but little-acknowledged fact by exerciseaholics — exercising isn’t enough to lose weight; you also have to eat less. Damn.

In about 15 minutes the test is complete, and Conners-Pace and I sit down to look at the results. While I was working up my heart rate, the mask over my mouth was monitoring gases and determining how my body was responding. By comparing this gas mixture with my heart rate, the program determines how much fat and how many carbs I’m burning at different heart rates. When you burn fat, you lose weight; running through carbs just tends to make you hungry. While you always burn both, understanding your most efficient zone will help you burn a higher ratio of fat to carbs.


Conners-Pace showed me how I kept burning more and more fat until my heart rate got to the point where my fat consumption started to drop while the carbohydrate burning increased. From a weight loss perspective, I learned that the key is to bring your heart rate up to the point of maximum fat burning, without going too far, and then keeping it there for a long, sustained aerobic workout at a nice, steady pace. Think skate skiing in Tahoe Donner’s mellow Euer Valley, instead of grunting and groaning your way up the steep and winding, double-black ‘I’m OK, Euer OK’ trail at Tahoe Donner Cross-Country.

Each person has their own unique VO2 max, or the rate at which they can continue to work out and efficiently burn fat. Lance Armstrong, who comes in at a whopping 86 ml/kg/min (milliliters of oxygen, per kilogram of body weight, per minute), has one that is much higher than the rest of us normal recreational athletes, who measure in the 50s. You can build up your max by training, but you are still limited by your body and genetics. The goal is not to become Armstrong, just to understand what your own capabilities are and learn how to use them to the best advantage.

Of course, nothing is simple when it comes to our bodies and the real key to training is varying your routine. While those long, steady workouts are good, pushing the envelope and going to your maximum heart rate increases your overall fitness and your body’s ability to burn fat more efficiently. It all gets back to a balanced training regime. By taking the VO2 test, I think I’m one step closer to understanding how my heart rate helps me achieve that balance.

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Though Tim spends most winters working on his V2 skate ski technique, this was his first encounter with VO2.


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