Which Comes First, Cardio or Weights_ - Alex Hutchinson [84]
Post-exercise nutrition has two primary goals. First, you want to recharge your body’s depleted energy stores so that you’re fresh and recovered before the next workout—whether that’s coming later the same day or later in the week. Second, you’re maximizing your fitness gains by providing the raw materials your body needs to synthesize the contractile proteins that increase strength and the mitochondrial proteins that boost endurance. “It’s a continuum between short-term recovery and long-term adaptation,” says Trent Stellingwerff, a Canadian scientist in the performance nutrition group at the Nestlé Research Center in Switzerland.
The key factors to consider are when and what you eat. For the first half-hour after exercise, the body is processing nutrients to repair itself at a dramatically elevated rate. After about two hours, this “window” is closed and the opportunity for any accelerated recovery is lost. This is where high-tech recovery bars and drinks can be useful, since they’re easy to have on hand immediately after you finish exercising—though it’s also easy to pack a sandwich in your workout bag.
In the past, conventional wisdom held that weightlifters should ingest protein to build muscle, while endurance athletes should focus on carbohydrates. Now researchers agree that both macronutrients are important no matter what type of exercise you’re doing, Stellingwerff says. Recent studies suggest that you should aim to consume about one gram of carbohydrate and 0.3 grams of protein per kilogram of body weight during the first hour or two after a typical cardio workout.
Some sports drinks tout very specific carb-to-protein ratios that companies say will optimize recovery and adaptation. Endurox, for example, has a 4-to-1 ratio—which happens to be the naturally occurring ratio in chocolate milk. In truth, “there’s no magic ratio,” says John Ivy, an exercise physiologist at the University of Texas at Austin and author of Nutrient Timing: The Future of Sports Nutrition. “Anywhere in the range from 2.5-to-1 to 4-to-1 works well,” he says. For very long workouts lasting a few hours or more, a higher ratio of up to 6-to-1 may be appropriate, Stellingwerff adds.
Whatever the ratio, the idea that the body needs fuel immediately after exercise is now widely accepted. But some people take this advice too enthusiastically, as research at the University of Massachusetts at Amherst’s Energy Metabolism Laboratory has shown. One of exercise’s prime benefits for those seeking to lose weight is that it heightens insulin sensitivity, which helps to clear sugars from the bloodstream. Researchers at Amherst asked 16 sedentary, overweight subjects to walk on a treadmill for an hour a day at a moderate pace, burning 500 calories. Half the participants replaced the lost calories by drinking a sports drink and eating immediately after the workout, while the other half were given nothing. Surprisingly, while insulin sensitivity spiked 40 percent in the abstaining group, no improvement at all was seen in the group that refueled.
These results suggest that if you’re trying to lose weight rather than trying to win races, you might be better off skipping the post-workout snack. That doesn’t necessarily mean fasting completely: Ivy points to other studies showing that people who take in a small amount of protein after exercise are less likely to overeat several hours later. But the basic message is clear, Ivy says: “If you’ve gone out and burned 300 calories by walking for 30 minutes, don’t refuel by taking a 500-calorie dietary supplement.” Let the magnitude of your workout dictate the size of the chocolate milk carton.
A POST-WORKOUT