Wednesday, January 28, 2015

Real Deal #5: Why Sports Drinks Are Only Good for Intense Workouts

“For most players, thirst is a good guide for hydration,” says Dr. Francis Wang, the team physician for Harvard athletics. "Athletes will not need vitamin and mineral supplements if adequate energy to maintain body weight is consumed from a variety of foods," the American Dietetic Association and American College of Sports Medicine say in a position paper on nutrition and athletic performance.
Toronto Star:
THE INTRODUCTION
Dr. Robert Cade, who invented the sports drink Gatorade in 1965 - along with Dr. Dana Shires, Dr. H. James Free and Dr. Alejandro de Quesada - died of kidney failure in 2007. He was 80.

Cade's researchers at the University of Florida College of Medicine determined a football player could lose up to 18 pounds – 90 to 95 per cent of it water – during the three hours it takes to play a game. Players sweated away sodium and chloride and lost plasma volume and blood volume.

Using their research, and about $43 in supplies, they concocted a brew for players to drink while playing football. The first batch was not exactly a hit. "It sort of tasted like toilet bowl cleaner," said Dana Shires, one of the researchers.

They added some sugar and some lemon juice to improve the taste. It was first tested on freshmen because Coach Ray Graves didn't want to hurt the varsity team. Eventually, however, the use of the sports beverage spread to the Gators, who enjoyed a winning record and were known as a "second-half team" by outlasting opponents.

It wasn't until 1991 when the company instructed America to "Be Like Mike" that sports drinks really launched in popularity. Today, Gatorade, which is owned by PepsiCo, is sold worldwide and has more than 80 percent of the $7.5 billion U.S. market.


THE EVIDENCE
Water performs a number of essential functions to keep your body in balance and hydrated, and these include regulating temperature of your body, transporting nutrients to cells and removing waste products. When you are performing physical activities that cause you to sweat, your body will lose a substantial amount of water, resulting in dehydration and possibly muscle cramps and nausea. It is important that you drink water whenever you feel thirsty, so that you will always be well-hydrated.

When exercising, the human body loses more water during normal activity than through sweat; this water must be replaced to maintain the body's health.

"Water provides no sodium, which helps the body hold onto water and helps fluid get to the right places in the body, like muscles and blood," says nutritionist Heidi Skolnik, M.S., CDN, FACSM, who advises both the New York Giants and the New York Knicks on healthy eating as well as drinking.

Your body soaks up electrolytes quicker because your electrolytes are depleted from sweat and exercise, and they soak up the water right along with it. Regular water works just fine too, it just doesn’t get absorbed as quickly.

WebMD:
Basically, a sports drink offers your body three things it might need before, during, or after vigorous exercise:
  • Hydration. The American College of Sports Medicine recommends that people drink about 17 ounces of fluid about two hours before exercise, to promote adequate hydration and allow time for the body to excrete any excess water. During exercise, they recommend that athletes start drinking early and at regular intervals in order to take in fluids at the rate they're losing them through sweating.
  • Fuel. The carbohydrates found in sweetened sports drinks provide energy to help delay fatigue, Clark says. When the body burns calories, it needs carbohydrates to replace energy lost. The longer the workout, the more carbohydrates are needed. The Gatorade Co. says lab tests have shown that 6% carbohydrate (14 grams of carbohydrate per 8 ounces of water) is the optimal percentage of carbs for speeding fluid and energy back into the body. As the carbohydrate level gets higher than 7%, absorption is slowed and therefore fruit juices and some sports drinks aren't recommended during exercise.
  • Electrolytes or Minerals. These are things like sodium, potassium, and chloride that athletes lose through sweat. When water goes out of the body, so do electrolytes. They speed the rate at which fluids empty the stomach, promote absorption from the small intestine, and encourage fluid retention. Sodium stimulates the absorption of both carbohydrate and water from the small intestine. It stimulates thirst receptors, so you are encouraged to drink more and hence replace fluids faster.

But many juices and sports drinks contain excessive amounts of sugar, and sugar causes your body to become dehydrated.

Men's Fitness:
THE VERDICT
Generally, you won’t need to consume anything except water during your workout, unless you are engaging in a strenuous activity or working out for longer than one hour.

The answer, it seems, lies in how much you're sweating.

The American College of Sports Medicine says that during exercise lasting less than one hour there's little evidence of any difference in performance between exercisers who drink beverages containing carbohydrates and electrolytes, and those who drink plain water.

Skolnik suggests frequently sipping small amounts of whatever you hydrate with to avoid a rare condition called hyponatremia, typically occurring in long distance athletes who drink too much water without the necessary sodium.

Sports drinks don’t appear to prevent hyponatremia. A study of marathoners by Harvard-based researchers found that 13% had some degree of hyponatremia, and that it was just as likely to happen among those who guzzled sports drinks during the marathon as it was among those who stuck with water.

Another reason to avoid chugging water? You can actually lose fluid. "Drinking a lot of water sends the signal to the kidney that there's some excess fluid in the blood and blocks the anti-diuretic hormone (vasopressin) which would help you hold on to water resulting in signaling you to urinate."

More important than selecting between the two is maintaining proper hydration before, during and after exercise.

More information:
» ESPN 30 for 30 Shorts: The Sweat Solution
» Patent: Compositions and methods for achieving improved physiological response to exercise
» New York Times: Are Vitamin Drinks Putting Our Health at Risk?

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