From lab to practice, the science of sports drinks and energy repletion
Sports drinks are perhaps the most common avenue employed for replenishment of fluids and calories, especially on the slopes. There is no shortage of information and marketing about the benefits of sports drinks for hydration, energy, or recovery. The scientific literature is overwhelming in its conclusions that sports drinks do in fact work. The question is which ones work, when do they work and what are the ingredients that make them work? We have tested several drinks here at our lab and can discuss some of our finding; for others we have a gag order. But before we get into the science of sports drinks and what’s available, it’s important to consider their role with respect to energy and hydration.
Sports drinks do different things. Some drinks are designed and marketed as pre-exercise drinks, some for consumption during exercise, and then others for post recovery. This is an important distinction because our need for fluids and calories is different depending upon whether we are exercising or not i.e. recovering. Drinks that are consumed during exercise are primarily designed to replenish fluid. If the exercise period extends beyond 60-90 minutes then they can also deliver calories that have clearly been shown to delay fatigue and enhance performance. A defining characteristic of during exercise drinks is their concentration. These drinks are typically around 6-7% concentration as this optimizes their passing through the digestion system and into the blood and muscle. This low concentration is also important because it does not adversely affect the blood flow to contracting muscle. However, when exercise is complete, the blood flow challenge is diminished and one can now consume food and beverage at a greater density and concentration. Thus “recovery” drinks tend to have more calories and indeed proteins and fats.
There has been a lot of recent activity regarding the contents and ingredients of sports drinks. The sports drink market leader “Gatorade” contains only carbohydrates (high fructose corn syrup) and has been criticized for its lack of protein that has been shown to enhance glycogen repletion and enhance recovery. A review of the literature does suggest a trend towards using a protein carbohydrate mix during both exercise and recovery. However, recovery from exercise has several additional challenges. Firstly, there is the glycogen repletion, secondly, there is the muscle damage and repair of muscle microtears, and thirdly, there is fluid replacement (although this challenge can be accomplished with water alone). The issue of muscle damage is particularly interesting as this is a limiting factor in repeat performances. We have done extensive work in the area of muscle damage and recovery and, with that in mind, set about developing and testing a new sports drink (CherryPharm). Previous work that we published indicated the role of both anti-inflammatories and antioxidants in recovery from exercise, especially high intensity exercise. It just so happens that Montmorency tart cherries are high in both these ingredients. The problem is that when you process cherries or indeed any fruit, and make a juice from concentrate, many active compounds are destroyed. We convinced a colleague of ours in food science to make a drink for test purposes that was basically “freshly squeezed.” Once we cleared that hurdle we set about designing our study to assess if the drink could in fact reduce muscle damage. The study was designed to use subjects as their own controls and in a controlled manner put subjects through a damaging bout of strenuous exercise. In essence we were creating the muscle soreness you experience after the early days on the slopes. Subjects were supplemented with either a placebo or a CherryPharm blend. These results were published in the British Journal of Sports Medicine and elsewhere and showed both a significant protective and increased recovery effect from the drink.
So the question is: what is the best drink? To answer that question you have to think about what your specific needs are. Do you just need fluid? Do you need fluid and calories? Do you need fluid, calories, and some anti-inflammatory and anti-oxidant effect? Once you have your answer then you can make a more informed decision about whether to go simple or complex. But remember, all drinks are not the same and your benefits will vary dramatically, so chose wisely.
Article by Declan AJ Connolly
Professor
Director, UVM Human Performance Lab
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