From: http://www.adidas.com/CN/micoach/articles/2010/2/the-new-science-of-workout-nutrition.aspx 

Guidelines for what to eat and drink before and after exercise used to be as simple as “have a snack” or “grab a water bottle.” Times have changed. Today, experts know that properly timed pre- and post-workout meals build lean muscle, improve performance, speed recovery, and even help you lose weight.

When to Eat

“Thirty to 60 minutes before and after exercise is the ideal time for snacks,” says Danielle LaFata, a registered dietician and performance nutritionist at Athletes’ Performance. Simply put, training requires energy; following a challenging workout, your energy is zapped, your muscles taxed. Your body is in a state of total breakdown, or what exercise scientists refer to as “catabolic.” To reverse to an “anabolic,” or rebuilding state, you need to refuel (eat) and rehydrate (drink). “The quicker you do this, the better,” says LaFata. You’ll preserve hard-earned muscle and kickstart the recovery process.

What you eat depends on many factors, which we’ll discuss below, but just know that eating something during this window of time is critical—even if you’re looking to lose weight. While it may sound strange to add more snacks, or meals, to your day to trim down, the key is to spread your calories throughout the day. So, you aren’t taking in more calories, you’re just eating more often and more strategically. By eating before exercise, you’ll have energy for a productive workout. As a result, you’ll burn more calories during your session.

While a pre-workout snack is sufficient for workouts under an hour, training sessions lasting more than 60 minutes require more energy to avoid fatiguing early. This means eating during the workout, too. “Grab a sports gel every 45 minutes, and then drink water the rest of the workout,” advises Amanda Carlson, director of performance nutrition at Athletes’ Performance.

How it Works

If you’ve ever felt like you hit a wall mid-workout, it was likely because your body was low on energy, or what we like to call “fuel.” Your body primarily uses carbohydrates for energy during exercise. Sure, you have energy stored from previous meals, but your pre-workout meal tops off your fuel tank, so to speak, so you won’t sputter out halfway through your training session.

By the time your workout is over, your body is spent. Here’s what happens:

• An intense workout creates tiny tears within your muscles cells and exhausts your energy supply.
• Waste products like lactic acid can build up in your muscles, causing fatigue.
• Levels of insulin and testosterone, your body’s main muscle-building hormones, tend to decrease.

It may sound strange to hear about your body being under siege because of exercise. But think of it this way: Like any challenge in life, it’s your ability to bounce back that makes you stronger. Exercise is no different. To repair itself, your body needs fluids, nutrients, minerals and vitamins.

The good news: There’s no better time to eat than within the first 30 minutes following a workout. Exercise stimulates your muscle cells, making them more receptive to insulin. Eating carbohydrates causes insulin levels to spike, which helps move your body into the desired anabolic state. Like a speedy messenger, the insulin drives nutrients from the blood to your muscles. The carbohydrates and protein in particular then spur on the muscle-building process.

In other words, exercise improves your body’s ability to deliver much-needed energy and nutrients where you need them most. “If you don’t take advantage of the 30-minute window to refuel,” says LaFata, “the body won’t recover as quickly, immunity will be suppressed, and your ability to build lean muscle will be reduced.”

What to Eat

While the research is fairly complex, the take-home menu is actually quite simple. Studies show that a 2:1 or 3:1 ratio of carbohydrates to protein is best, depending on the intensity and duration of your workout. For a short, low to medium intensity workout, a 2:1 ratio is enough. But for longer, harder runs, aim for a 3:1 or 4:1 ratio—you’ll need the extra carbohydrates to help refuel your depleted energy stores.

Keeping those ratios in mind, aim for a combination of 15-30 grams of protein and 30-120 grams of carbohydrates before and after your workout. You’ll boost energy levels to stay sharp, both mentally and physically, throughout even the toughest of workouts—and you’ll recover better afterward.

As you’ve heard before from miCoach, every runner is unique. Training needs differ, as do your nutritional needs based on factors such as age, fitness, body size and goals. What follows is a basic set of guidelines, courtesy of the performance nutritionists at Athletes’ Performance.

Using the chart, select appropriate pre- and post-workout snacks based on your weight and the intensity of your workout. Don’t feel constrained to these options. They’re simply meant to be ideas to help you get stared and inspire your inner performance chef. Keep in mind that calorie counts vary, so take your overall daily calorie intake into consideration when choosing your workout nutrition. Bon appétit!

作者是世界顶级运动训练机构 Core Performance 的一位杰出教练。 Core Performance 已与 adidas 携手合作，共同创造 miCoach 所独有的训练方式。 请访问 CorePerformance.com 了解更多详情。