Isotonic drinks
Claims: Improve stamina and ward off dehydration.
Evidence: Isotonic drinks (eg Lucozade Sport and Gatorade) contain 4-6% of easily digestible particles of carbohydrate to top up the body's glycogen (or energy) stores, which become depleted during exercise. They also contain small amounts of sodium, which enhances fluid absorption in the gut. But they can be worse for your teeth than cola, says Anthony von Fraunhofer, director of biomaterials research at the University of Maryland dental school. He found that while most cola drinks contain acids, sports drinks contain additional, organic acids that can speed damage to the enamel.
Verdict: Most top athletes use them, but "they really are not necessary in activities lasting less than an hour when plain water will suffice," says Jeanette Crosland, a consultant nutritionist to the British Olympic Association. Even in long-distance events, do-it-yourself versions work just as well and are cheaper. Mix one part water with one part fresh orange juice and a small pinch of salt.
Cherry juice
Claims: Reduces post-workout muscle aches and pains.
Evidence: A study in the most recent British Journal of Sports Medicine looked at gym-goers who were given either a placebo or the juice of 50-60 Montmorency cherries twice a day for eight days. Midway through the trial they did 40 bicep curls, lifting as much weight as they could with one arm. Two weeks later, they repeated the process on the opposite arm, having taken the other drink. There was less reduction in strength and less pain with the cherry juice, reported researchers at the human perform-ance laboratory of the University of Vermont.
Verdict: "There is a high concentration of anti-oxidants and anti-inflammatories in all cherries, but Montmorency cherries in particular," says Professor Declan Connolly, who led the study. Lots of ordinary cherries would have the same benefits. You can buy cartons of pre-squeezed juice in many supermarkets.
Black coffee
Claims: Improves endurance and fat-burning; speeds recovery.
Evidence: Several studies, including some conducted at the Australian Institute of Sport (AIS), have shown that there are substances in caffeine that trigger the release of body fats into the bloodstream during activity. This means fat is burned during exercise, rather than carbohydrate, the body's primary choice of fuel. Carbohydrates are stored in the muscle as glycogen but the amount that can be stored is limited. If you burn body fat first, it reserves carbohydrate for later use. A study at the University of South Carolina found that drinking one or two cups of coffee up to an hour before a gym session can delay or prevent post-exercise tiredness by up to 60%.
Verdict: Peter Fricker, director of the AIS, says 1-2 cups of black coffee before (or during) exercise is enough for most people: "It works in small doses and there are no gains by taking larger doses."
Chocolate milk
Claims: Aids recovery from intense workouts.
Evidence: A recent study published in the International Journal of Sport Nutrition and Exercise Metabolism looked at a group of cyclists who rode until their muscles were depleted of energy, then rested for four hours before cycling again to exhaustion. While resting, they were given drinks of either chocolate milk, the isotonic drink Gatorade or the high carbo-hydrate and protein Endurox sports drink. When asked to get back in the saddle, the cyclists who had drunk the chocolate milk cycled about 50% longer than those who drank Endurox, and about as long as those who drank the Gatorade before they became exhausted. Milk also contains key nutrients, such as calcium and vitamin D, in quantities that regular sports drinks can't match, says the Indiana University research.
Verdict: "Our results suggest that chocolate milk has an optimal ratio of carbohydrates to protein to help refuel tired muscles," says Dr Joel Stager who headed the Indiana study. Top American swimmer Michael Phelps drinks chocolate milk between races.
Oxygenated water
Claims: Extra oxygen in these commercial drinks, such as OGO - up to 35%, claim some manufacturers - means the body gets an aerobic kick with every sip.
Evidence: Professor John Pocari, an exercise physiologist at the University of Wisconsin, recently measured what happens when runners thought they were getting a performance boost in the form of "super-oxygenated" water in a trial for the American Council on Exercise. Subjects completed three separately run 5-km time trials with half the group drinking a large glass of plain bottled water and the others taking what they thought was super-oxygenated water (but was, in fact, tap water) before they started. Results showed that runners covered the distance an average 83 seconds faster when they thought they were drinking oxygenated water.
Verdict: "Most of the oxygen in the water would escape into the atmosphere when you open the container," says Dr Howard Knuttgen, a physiologist at Pennsylvania State University. "The exchange of gases that allows the body to take in and utilise oxygen is a function of the respiratory, not the digestive system. Any intake of so-called super-oxygenated water would be of no use in improving athletic prowess."
Flat cola
Claims: Improves endurance.
Evidence: Professor Louise Burke, head of nutrition at the AIS, showed that sipping 1-2 cups of flat cola (or coffee) boosted the endurance capabilities of athletes by up to 3% - which is quite significant in long- distance events. Because of its caffeine content, cola has similar fat-burning properties to black coffee (see above). But the sugar it contains could also play an important role. Last year, a study at the University of Birmingham, published in the Journal of Applied Physiology, put cyclists through three two-hour exercise sessions while giving them one of three different drinks - glucose, glucose mixed with caffeine or plain water. Their results showed that caffeine increased the amount of sugar, or carbohydrates, absorbed from the glucose drink by 26%, which could explain cola's effects. It is one of the most popular drinks among elite runners in the London Marathon every year.
Verdict: Jeannette Crosland says: "Used with exercise and diet, caffeine drinks could help you to reach your fitness goals faster"
