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Timing is Everything: When you eat is as important as what you eat when working out


Most people know not to eat a gallon of Ben and Jerry’s before an intense workout and that drinking water to hydrate a sweating body is good. That guidance is okay as far as it goes, but operating a complex machine such as the human body with only a meager list of such maxims is akin to feeding a racehorse Mountain Dew and cheesecake so he’ll speed from the sugar—you can do better.

John Ivy
Dr. John Ivy

Dr. John Ivy, chairperson of the Department of Kinesiology and Health Education in the College of Education at The University of Texas at Austin, has spent the past thirty years looking at simple, healthy options for building strength, endurance and muscle mass. What he has discovered is that timing is everything.

For decades, serious athletes as well as hard-pushing weekend warriors have searched for the holy grail of exercise nutrition, following one trend after another in an effort to capture the magic formula that increases strength, endurance and lean muscle mass.

Conventional wisdom in the late 1960s and early 1970s pointed to carbo-loading as a way to super-saturate muscles with carbohydrate and fuel cross-country skiers as well as long-distance runners and endurance cyclists. For strength athletes, that paradigm was flipped on its head and protein intake was stressed.

With each new wave of information and fad-following, the one element that often seemed to be missing was strong, conclusive scientific substantiation.

When Ivy, a world-renowned expert on the role of nutrition in exercise performance, began to study the maximization of physical performance, his research concentrated on the cellular level and a somewhat overlooked element of nutrition—timing. His goal was to explain, in scientific terms, why an athlete sees particular effects when she supplements at specific times with certain nutrients.

“When you exercise,” says Ivy, “the muscles become very sensitive to certain hormones and nutrients, and you can initiate many highly desirable training adaptations if you make sure the correct nutrients are present. This increased sensitivity of the muscles only lasts for a limited length of time, so the element of time becomes absolutely crucial. If you miss this window of opportunity, there’s no way you can stimulate the muscle adaptations to that extent until after the next bout of exercise.”

To understand Ivy’s breakthrough findings, it’s helpful to revisit Biology 101 and look at the delicate, elaborate symphony of hormone activity and energy replenishment occurring behind the scenes when you run, swim, power-lift, ski or cycle.

Three Misconceptions About Exercise Nutrition: For exercise lasting fewer than 45 minutes, water is fine. You have 18-20 hours after workout to restore muscles. Carbohydrate is nutrient for aerobic athletes, and protein is nutrient for strength athletesAs with any good high-performance product, a contracting muscle needs fuel. Adenosine triphosphate (ATP) is the only energy source that can drive muscle contraction, but, like a car that gets two miles to the gallon, muscles can only store enough ATP for a few seconds of high intensity contraction. If muscle contraction is going to be sustained, and you want to keep sprinting or pedaling up a steep incline, the muscle needs this ATP to be continuously replenished.

Fortunately, the body has ways of generating more ATP and keeping the marathon-runner running and the soccer player blocking goals. Through the anaerobic pathway, glycogen and creatine phosphate rush to provide rapid energy for intense bursts of activity as you speed from third base to home plate. Through the aerobic pathway, fat, carbohydrate and protein fill the void and are used to provide sustained energy with much more efficiency than the anaerobic pathway.

As systems scramble to meet the muscles’ appetite for ATP, wear and tear on the body can occur, leaving you tired, dehydrated and with reduced blood volume, a compromised immune system and muscle damage. The degree of the negative effects correlates with the intensity and duration of exercise.

“What we found in our studies,” says Ivy, “is that you can recover more effectively, work out harder more frequently, increase muscle mass and enhance the physical adaptations that are happening when you exercise just by minding what supplements you use and when you supplement.”

Ivy tested distance runners, triathletes and strength athletes between the ages of 19 and 35, hoping to determine what allowed for the fastest recovery of muscle glycogen, a key fuel for contracting, hardworking muscle.

Female athlete drinking sports beverage
Sports drinks that have a 4:1 carb/protein ratio improve endurance, reduce muscle damage and speed recovery after exercise.

When the athletes ingested a carbohydrate supplement immediately after exercise, they had a much higher rate of glycogen recovery, which is fuel for the muscle, than if the supplement was delayed for several hours. Ivy also discovered that once this fuel storage process kicked in it could be maintained at a rapid rate if the individual supplemented at two-hour intervals for up to eight hours after exercise ended.

Although approximately 1.4 grams of carb per kilogram of body weight maximized glycogen storage, Ivy found that more of a seemingly good thing did not end up being better—the rate of glycogen storage could not be increased with an increase in carb intake.

The surprising addition of a limited amount of protein, however, sparked a chain reaction that does a body good.

When protein is added to carbohydrate, the insulin concentration in the blood rises. Insulin is a facilitator and stimulates glucose uptake by the muscle and the conversion of glucose into the highly valuable glycogen, as well as increasing the rate of protein synthesis when the supplement is taken immediately after exercise.

With his research findings, Ivy identified a span of time during which exercise and post-exercise nutrition is very important to the athlete who wants to improve endurance, reduce muscle damage, maintain immune function and jumpstart a much quicker recovery.

According to Ivy, “nutrient timing” begins 30 minutes before exercise, when one should fully hydrate and raise blood glucose levels by consuming approximately 14-20 ounces of water or electrolyte solution. This delays the development of dehydration, hastens the onset of sweating and moderates the rise in body temperature.

During exercise, smart nutrition choices become even more important. In order to spare muscle glycogen, limit cortisol and free radical levels, prevent dehydration and set the stage for faster recovery after a workout, Ivy found that fluids should be replenished every 15 to 20 minutes, if possible.

Effects of Increasing Dehydration on Physical Performance. As body water loss increases, effects on body's physical performance worsenIn one study with cyclists, Ivy discovered that drinking a fluid containing carbohydrate and protein in a 4:1 ratio improved endurance 57 percent compared with water and 24 percent compared with a carbohydrate drink.

Because muscle breakdown occurs faster during exercise, consuming a supplement that includes protein while exercising gives muscles some of the protein they need to produce extra energy. The result is less muscle damage. Similarly, maintaining blood glucose levels by ingesting carbohydrates during exercise leads to less depletion of glycogen stores and less fatigue.

Wrapping up the metabolic window of opportunity around exercise is the very important 30 minutes following a workout. In fact, according to Ivy, this is the most important time for minding nutrition p’s and q’s.

In the 30 minutes following a workout, a muscle’s potential to rebuild peaks, and it is extremely sensitive to insulin. To take full advantage of the muscle rebuilding benefits that can occur in this golden window of opportunity, the right combination of nutrients, such as carbohydrate and high quality protein, should be consumed within 15 to 45 minutes after exercise.

Insulin sensitivity, and the ability of muscle fibers to pack in as much energy as possible, falls significantly one hour after exercise. After two hours, muscles not only lose their sensitivity but actually become insulin resistant and muscle breakdown occurs. Even though activity has stopped, the muscles continue to lose protein and nutrients without supplementation.

“Paying attention to what you eat or drink and when you consume it is a lot easier, cheaper, healthier and safer than using some plant steroids, androstenedione or creatine supplementation, for example,” says Ivy. “Just following a good basic diet and supplementing at the right time may not sound all that exciting, but solid scientific research says it works and yields increases in muscle mass, strength and endurance. It can even protect your immune system and keep you from getting as many colds and upper respiratory ailments.”

Muscular arm of weightlifter holding a large weight
Supplementation should begin 15 to 45 minutes after exercise ends or you risk missing the metabolic window of opportunity.

Ivy’s pioneering findings in the area of sports nutrition are presented in his two latest books, “Nutrient Timing” and “The Performance Zone,” which he co-authored with Dr. Robert Portman, president and director for PacificHealth Laboratories.

With “Nutrient Timing,” the guidance is geared to strength athletes and bodybuilders. In it, Ivy emphasizes that attention to timing and nutrition during the muscles’ 24-hour growth cycle can help weight trainers break through plateaus, increase muscle mass and suffer less soreness and stiffness after workouts.

“The Performance Zone” serves as a sports nutrition action plan and workbook for all levels of athletes, with sports-specific information from Olympic swimmers, exercise physiologists, world champion triathletes and professional sports stars. In order to encourage amateurs as well as more serious exercise enthusiasts to implement nutrient timing, the book includes, among other things, information on calculating the number of calories expended during different types of exercise, how to determine fluid and nutrient needs during exercise and a comparison of the many sports drinks on the market. The specific needs of female athletes as well as active children also are addressed.

“At any given time, there’s a lot of information out there about how to train better,” says Logan Schwartz, an Austin strength conditioning coach who trains professional as well as high school and college athletes. “But there’s not much good information. Dr. Ivy’s nutrient timing system, which I and my clients use, stands apart because when you look behind the claims you find valid scientific research. Attention to nutrition as a vital part of improving physical performance is really a fairly new, revolutionary thing, and it’s turning out to be very important.”

Cyclist riding his bike across campus
In exercise, as dehydration increases, quality of performance will continue to decrease.

Although Ivy now finds himself talking to reporters and interested groups from coast to coast about nutrient timing, sports nutrition might be described as something of a second love. For the past 30 or more years the bulk of his research has been devoted to diabetes and, most specifically, the effects of exercise on diabetes.

“One thing we discovered that’s very significant,” says Ivy, “is that muscle contraction, which happens when you exercise, increases glucose uptake differently from the way that insulin increases glucose uptake. Diabetics who are insulin-resistant have muscles that cannot efficiently take up glucose by insulin stimulation, but the muscle will take up glucose in a normal manner with muscle contraction. That means you can help regulate blood glucose levels through exercise. That’s good news and a natural way to address the problem.”

Having spent his professional career studying exercise and nutrition, one would expect Ivy to practice what he preaches. And he does.

A former college baseball player, he is trim and athletically built, with an office ringed in pictures of his trim, muscled and athletic children, one of whom is test-driving the nutrient timing system along with Ivy.

Glancing at Ivy and the photos of his cheerleading, baseball-playing progeny, you might be tempted to argue that the family simply enjoys good genes. But that’s like watching the smooth, perfect arc of a Tiger Woods swing and saying he’s just awfully lucky again and again—you’re ignoring the importance of hard work…and good timing.

Kay Randall

Photos: Marsha Miller

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  Updated 2014 October 13
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