By Page Love, MS, RDN, CSSD, LD, USPTA, and Colter Ellis, Dietetic Intern
From daily hydration outside or hydrating in the middle of a tiebreaker, there are many different beverage and sport food options to choose from that claim to enhance your energy levels. But should you take a risk on trying all the popular caffeinated sport foods and drinks before you walk onto the tennis court? Why do so many sport foods contain caffeine? Caffeine is a popular and common ingredient added to some of these energy and hydration products because of the perceived boost. Regarding improving performance without side effects, proceed with caution — especially when it’s hot outside.
Higher caffeine intake can increase your heart rate, adding extra stress to a cardiac system already in overload with the high anaerobic demands of tennis play. This, in turn, can accelerate dehydration, increasing your risk for heat illness from dizziness, loss of motor control accuracy or shot precision, to muscle cramps and even all out-heat exhaustion. Any one of these side effects can cause a negative match outcome or default situation!
Beware of energy drinks
Energy drinks have been around for decades and continue to gain popularity in the sport arena. They may contain vitamins and minerals, and carbohydrate energy. However, these drinks often include multiple sources of herbal stimulants and other ingredients that are stimulatory including ma huang, guarana, ginseng, kola mate, taurine, theophylline, theobromine, glucuronolactone, and high levels of B-vitamins. Many energy drinks use multiple combinations of these ingredients (often referred to as “stacked”) with stimulants increasing risk of dehydration and heat illness! Additionally, these beverages often include the same amount of caffeine as two cups of home-brewed coffee (between 200-300 mg of caffeine, on average). Other ingredients, such as taurine, can be presented in misleading ways. This nutrient has been shown to help with muscle contraction and fatigue, but while this might be beneficial by itself, the combination with other stimulants increases risk of dehydration. Also, high B-vitamin levels — especially high levels of niacin — can cause vasodilation and muscle flushing often at levels much above the safe dietary intake recommendations.
Why is caffeine of concern? Caffeine is a nervous system stimulant, causing a false sense of energy by increasing your heart rate, blood pressure, breathing rate, and increasing the rate that all organs function, including the rate your kidneys excrete urine, acting as a diuretic causing your body to excrete fluids, thus lowering body fluid levels (and less fluids for cooling muscles). These side effects are amplified when caffeine is combined with herbal plant extracts that mimic caffeine’s effects. While this may feel like a needed boost in your tennis playing performance, it can be detrimental by causing you to become tired sooner, partially from dehydration but also as the stimulation from caffeine and herbal stimulants wear off. Drinks with higher levels of caffeine can dehydrate you more than the liquid itself hydrates, thus negating the benefit of using these beverages for their original purposes to hydrate and provide real energy. Additionally, caffeine also acts as an appetite suppressant, making it more difficult to feel your hunger to fuel adequately before, during, or after your match.
What is a better choice? It is known, however, if you are a regular caffeine consumer, you may be less sensitive to caffeine and at less risk for dehydrating side effects, but the added consequences of “stacked” caffeine-like ingredients definitely outweigh any perceived energy gains you may think you have with using an energy drink.
Also be wary of pre-workout drinks that contain caffeine
Pre-workout drinks that contain caffeine (and most of them do) also can be enticing, with claims of boosting your energy. These are similar to the composition of energy drinks and all have their own formulations that largely include caffeine and other similar stimulants listed above. The caffeine content in these products still can cause dehydration and work against the goal of pre-hydrating before a tennis match! Caffeinated pre-workout drinks also cause an increase in sweating, intensifying loss of body fluids before you even start playing, leading to early-on fatigue in a match. Dehydration, fatigue, weakness, and loss of precision in shot execution all can be symptoms of becoming dehydrated.
Choose “real” sports beverages instead
Sports beverages that contain adequate electrolytes and carbohydrate energy such as Gatorade, Powerade, Liquid IV, and Pedialyte Sport are the most appropriate choices for hydration, especially for long matches or matches in the heat. Ideal composition is a 6-percent to 8-percent carbohydrate energy solution and 100 mg of sodium, as well as other key electrolytes lost in sweat such as chloride and potassium. Also, be aware that sugar-free beverages that only contain electrolytes (Gatorade Zero, Body Armour Lyte, Powerade Zero, Biosteel, etc.), will not provide energy for longer matches.
Non-caffeinated sports beverages and pre-workout beverages are superior choices for hydration before, during, and even after tennis. And the energy drinks should be kept far from the tennis court!
What about caffeine energy gels and chews?
The last sport food to be wary of are caffeinated energy chews and gels. These are carbohydrate mixtures often also containing electrolytes in a thicker solution form. Most brands have both caffeinated and decaffeinated options. Those that contain caffeine contain much less caffeine than energy drinks, but if you are caffeine sensitive, avoid those as well. Definitely do not combine these with caffeine-containing energy drinks or pre-workout drinks! Perfect for some quick, absorbable energy and easier to digest than more solid carbohydrate foods, these sport food gels are quickly becoming a common choice for tennis players. Because the caffeine content is usually much lower than their drink counterparts (averaging 30-75 mg caffeine per serving), these can be a safer option for those who feel they can benefit from a small amount of caffeine. For those who are sensitive to caffeine, choose the decaffeinated options, so make sure to check the labels. Also, make sure to drink plenty of water with these as they do not contain enough liquid to hydrate and are really meant to be a compact energy and electrolyte source to be combined with water to fully replace a sport beverage.
Five top warning signs to consider about caffeine sport food intake
- Many energy drinks contain between 200-300 mg caffeine, and those with heart conditions, such as high blood pressure or caffeine sensitivity, should be mindful of caffeine intake. You should limit your daily caffeine intake to 400 mg or less, bearing in mind the combined total for those who may drink more than one can a day, in addition to any coffee or other caffeine source.
- Be aware and try to avoid the following ingredients that indicate stimulant side effects: ma huang, guarana, kola mate, ginseng, taurine, theophylline, theobromine, and glucuronolactone.
- Caffeine is an appetite suppressant and may make it difficult to be hungry for pre- and post-workout fueling snacks. This may also suppress overall hunger and can lead to less adequate fueling throughout the day.
- High caffeine intake consumed within five hours of sleeping can disrupt sleep patterns. This may result in fatigue and prevent restful sleep. So, watch out for energy drinks before evening tennis, but also be aware that your next morning tennis also may be affected by inadequate sleep.
- Caffeine-containing energy drinks can be dehydrating, especially the ones with 300 mg or more caffeine. This can cause unintentional increased heart rate during exercise with leads to increased kidney function and increased urine output.
Page Love is an avid ALTA participant and sport dietitian/nutrition advisor for the WTA and ATP professional tours, serves on the USTA sport science committee and holds a Masters in Sport Nutrition and works with players of all ages in her Sandy Springs practice. You can reach her at nutrifitga.com. Colter Ellis holds a bachelor’s in Nutrition and Dietetics from the University of North Carolina Greensboro, and is a dietetic intern at Life University. She is a recreational and former high school tennis player, and is interested in both clinical and sports nutrition.