Gym junkies on junk food

As a long Jersey winter reluctantly yields to spring, many of us will choose a sunny game of ultimate frisbee over a half-hour on the Stairmaster or treadmill. But while the crowds in Stephens Fitness Center thin and the lines for exercise machines disappear, others will keep coming back to the gym — for the a/c, the reassuring sense of communal masochism and, most of all, the peace of mind that comes from reading our digitally-displayed calorie loss. Yes, for those balancing a seasonal penchant for a Thomas Sweet's blend-in with the loftier goal of attracting mating partners on the beach, we will step, run, bike or "ellipse" with added vigor, hoping to push our caloric burn to truly pyrotechnic heights.

Fortunately, such hormonally-driven discipline is well-founded. However, there are myriad dietary prescriptions to sort through, from 'Atkinsing' your way into an egg and meat cholesterol bender to 'Zoning' it with an aesthetically pleasing 40-30-30 balance. Yet while the nutrition wars rage on, good-old fashioned exercise remains chic and acceptable across the board. As Matt Brzycki, guardian of all that is good and wholesome in Princeton's million-dollar fitness center, explained to me, the classic formula of three to five times a week for 20 to 60 minutes of intense activity remains the scientifically recommended allowance for staying in shape (or getting there).

But exercise, like education, is often pursued for its side benefits rather than its intrinsic good. Yes, I'm talking about eating 'bad food' without guilt, shamelessly throwing nutritional sense to the wind as we embrace the psychological (and metabolic) capital gained through a tiring workout: arduously climbing 100 Stairmaster flights to the tune of Laura Branigan's "Gloria," all for the thrill of wantonly quaffing a "post-workout" Halo Pub shake.

Fortunately, this trade-off is legit so long as we are honest about the exchange rate between sweat and sweets. It takes a lot longer to burn off 300 calories than it does to consume them. What one sheds in 30 minutes can be reacquired in 30 seconds. But thanks to the wonders of modern exercise technology, we can weigh those choices with a great deal of accuracy.

How do the exercise machines count the calories we expend? The method to their magic is a formula based on weight of the exerciser and intensity of activity. For example, the treadmill employs a mathematical equation for calories burned per minute while running on a flat surface: [(Speed in meters/min x 0.2) + 3.5] x [Body weight in kg/200]. (Calories are a metric unit — the amount of heat needed to raise one gram of water one degree Celsius — so you have to use meters and kilograms for these equations. As a benchmark consider that a 70 kg individual running five km in 20 minutes burns a whopping 18.725 calories/minute.) Step machines and stationary bikes use similar formulas.

While any Princetonian could crunch those numbers in his or her head while running, reading the New York Times and watching ESPN, the machines' internal computers save us the effort while also accounting for changes to incline and intensity. Although there is a bonus "afterburn" of calories in the period following heavy exercise, these red-lit readouts give the best estimate for the caloric drain of a workout. So a final tally of "Calories spent: 400" means just that, an amount nearly undone by ingesting a Balance bar and a 20oz. Powerade.

Denise Bollinger, a local health promotion specialist, cautions that one should not exercise just to be able to eat more. Still, if you know you are going to miss a workout then it is sensible to take in fewer calories than you consume during a day of cardio exercise. In other words, the trade-off of sweat for sweets can go the other way as well. When a student is swamped because of generals studying or thesis writing he or she can opt to eat less junk food to gain time by skipping the gym. Still, if done too frequently, that choice may have hidden costs since exercise reduces stress and builds self-confidence, crucial factors for producing superior academic work.

I've always thought the maxim "moderation in all things" was a bit extreme. It is comforting to know that our cardio machines can help us make informed decisions to buy off nutrition through exertion and periodically enjoy a glut of caloric decadence. Jason Brownlee is a politics major from Raleigh, NC. He can be reached at brownlee@princeton.edu.