The Science of Sports Drinks

A tactical perspective on hydration.

The Science of Sports Drinks
By: Martin Day

Water makes up about 70 percent of the human body. The intake of water is obvious, so it may be overlooked when job demands take priority over thirst and hunger. Staying hydrated and nourished while on duty, and especially during tactical operations is imperative for performance. Dehydration of greater than two percent of bodyweight degrades aerobic ability as well as cognitive and mental performance in warm environments. 

General patrol, use of force, and tactical deployments are athletic events. Like other athletic events, the body is taxed and the need to recover or maintain performance can be minimal or deadly serious.

Water is the primary consideration for combating dehydration. Pre-hydration, i.e., taking adequate fluids and meals before a water-taxing event, should be implemented, in addition to replenishing fluids during and after an event.

Choosing how to replenish fluids is influenced by the type, duration and intensity of an activity as well as environmental factors such as heat and humidity. Various types of tactical operations and callouts dictate whether nourishment can be replenished at regular intervals. Thus, fluids may be the only intake of nutrients during a particular operation.   

Sports drinks can be used to maintain hydration and electrolytes and provide carbohydrates.  Replenishing carbohydrates is important because carbohydrates are the preferred fuel for muscular contraction. The composition of a sports drink should mimic the composition of the nutritional deficit caused by the athletic event.  

There are three general types of sports/rehydration drinks. First, isotonic drinks. These contain similar water, mineral and sugar content as the human body. Second, hypertonic drinks. These contain higher concentrations of minerals and sugar than the human body. Third, hypotonic drinks. These contain lower concentrations of minerals and sugar than the human body.

Every officer has a story that involves being drenched in sweat. The evaporation of sweat is the basis for cooling the surface of the body and eventually the core temperature. The addition of body armor, winter uniforms, headgear and the like exacerbate heat stress, and the body responds to the increase in temperature by sweating. Even in cold weather, body armor and tactical uniforms are not permeable so the rate of sweating increases while the body’s ability to cool is worsened.  

Isotonic Sports Drinks

Isotonic sports drinks contain similar water, mineral and sugar content as the human body. The greatest number of common sports drinks (Gatorade G02, Powerade Ion4, Vitamin Water, Powerbar, All Sport) is isotonic. Lightly sweetened coffee and lightly sweetened tea are also examples of isotonic beverages, mentioned due to their wide consumption in law enforcement.   

Isotonic drinks should be used if the primary concern is the loss of water, minerals and carbohydrates. Water loss occurs during long bouts of low-intensity (as a measure of heart rate) exertion. Water is lost through sweat, respiration and urination. Sodium and other minerals are lost through sweat, but not respiration.   

The theory behind isotonic drinks is based on replenishing minerals lost in sweat and carbohydrates expended during strenuous exercise. Various position papers and studies support use of isotonic drinks to maintain and increase performance for activities lasting one hour or more. Most isotonic sports drinks contain between 10 and 20 grams of sugar per 8-ounce serving.     

Performance during tactical operations or trainings that last more than one hour may be optimized by using isotonic sports drinks. There is no such thing as a typical length of a tactical operation, whether emergency callout or planned missions, so the use and availability of sports drinks should be incorporated into training. 

Hypotonic Sports Drinks

Hypotonic drinks contain little or nothing in the way of sodium, vitamins or minerals. Water is the original and most abundant hypotonic sports drink. An example of a commercial hypotonic drink is Slazenger S1. Unsweetened tea and coffee are also hypotonic. 

If ample food is consumed and the loss of electrolytes is minimal, then hypotonic beverages would be the preferred method of hydration. Unfortunately, a balanced meal is not always a reality during police work. Meal breaks are often unscheduled and emergency response takes precedence over nutritional timing. Loss of sodium may be mitigated because the typical American diet is high in sodium, but other trace minerals may be lacking. 

Hypotonic drinks should work best for rapid hydration and when the primary concern is the loss of water and not minerals and carbohydrates. During very cold weather with low-intensity physical effort, the greatest loss of water is through respiration (and urination) with little mineral/sodium loss. What this means is that absent high temperature, intense operations and training hypotonic drinks may be the best form of hydration. 

Hypertonic Sports Drinks

Hypertonic drinks contain a higher concentration of minerals and/or carbohydrates than the human body. Hypertonic drinks are not as easily digested as hypotonic and isotonic beverages since they require more digestive work. Hypertonic drinks are more slowly absorbed in the digestive tract and may cause cramping, discomfort and even nausea in some circumstances. 

During intense physical exercise, intense heat, or intensive mental stress, the nervous system signals blood away from the digestive tract and toward the skeletal muscles as part of the fight or flight response. This can exacerbate poor digestion of hypertonic drinks and solid foods during callouts, tactical operations and intense physical training. Hypertonic drinks appear to be best suited for replenishment and recovery after the event, not during. 

Fruit juices, milk and coffee with heavy cream are examples of hypertonic drinks. There are few ready-made Hypertonic Sports Drinks and most commercially available hypertonic sports drinks are sold as powdered mixes. Gatorade offers a ready-to-drink hypertonic in their G03 series of products (this product includes supplemental protein).


Sports Drinks During Tactical Deployments

The absorption of nutrients and water is influenced not only by the composition of the drink, but also on the contents of the stomach. The rate of gastric emptying affects the ability of a drink to rehydrate and whether the drink’s content of carbohydrates and trace minerals are absorbed and transported to the cells.  

Food can change the rate of absorption of the water and nutrients. Responding to on-duty emergencies precludes a “pre-game” meal that is employed by athletic competitors. Planned warrant services and tactical operations will allow for meal planning, so practice eating and hydrating should be done on training days. A healthy diet balanced with clean sources of fats, proteins and carbohydrates should be followed for general health and is important to stay hydrated. 

High-salt diets interfere with cellular hydration and high-fat diets can interfere with the speed and rate of food absorption. The most suggested method for hydration during athletic events is to start with a moderately large volume and repeatedly drink small amounts of fluid during the duration of the event. This method is likely a good way to stay hydrated over a period of prolonged exercise and operations that occur in hot, humid environments.  

Each officer should experiment with what ways of hydrating works best personally while training since a negative gastro-intestinal effect can be disastrous on the road or a tactical operation. For short-duration events on hot days (or days when body armor and equipment cause a lot of body heat) water replacement should be a priority.

Isotonic or hypotonic drinks with less than 8 percent carbohydrates are the theoretical best choice. For longer duration, moderate climate endeavors the theoretical choice would be a drink containing 10–15 percent carbohydrate content.   

Ready-made drinks can be diluted with water to achieve the proper ratio. Powdered drink mixes can be made with less water to achieve higher carbohydrate ratios. Since nervousness is never factored in the advertising copy or physiological studies of sports drinks, tactical athletes have to account for the effect adrenaline; cortisol and stress will have on any intake of fluid or food.

Immediate to physical performance, phosphates, magnesium and iron have an influence over oxygenation of blood and cellular respiration. Working muscles are like engines in that they require fuel (carbohydrate) oxygen and spark (neurological firing based on calcium.) 

None of us should be suffering from malnutrition, but expending the body’s stores of carbohydrates and trace minerals has shown a negative effect on athletic performance. Water loss, glycogen depletion and loss of minerals can easily occur during prolonged police efforts.   Lengthy callouts and training sessions test and tax the body in ways that are similar to sustained athletic events. 


A sound diet of wholesome foods complemented by frequent intake of water should be followed daily. This foundation is the basis for overall health. Staying hydrated in the gym is an easier task than staying hydrated on duty or on operational details. It is important to frequently take in fluids and have drinks available on hand. If your diet lacks vegetables and fruits, you may wish to rehydrate with a drink that will provide essential minerals. Hypertonic fluids may be needed if meals are skipped because of hectic call volume or the general busy schedule of modern life. 

Most commercially available sports drinks will meet the basic needs of providing water, some minerals and simple carbohydrates. Just as we should train with a particular weapon before using it on duty, experimenting with the different sports drinks during training will let you know which one works best for you.

For their part, Gatorade makes it clear which of their drinks to take when. The Prime 01 product line consists of a pre-game fuel in a gel consistency, positioned for consumption prior to athletic activity. Traditional Gatorade products such as Gatorade Thirst Quencher (Original Gatorade), G2, and Gatorade Powder are categorized under the Perform 02 classification, representing their intention for consumption during periods of physical exertion. Recover 03 refers to a post-workout protein and carbohydrate drink, formulated with the consistency of a sports drink. The composition of this beverage reflects its intention to provide both hydration and muscle recovery after exercise.

Personal taste and tolerance will probably trump the theoretical application of sports drink use.   For best practice, each individual should decide if sports drinks are the right choice for themselves. Some find they like or dislike certain flavors and swear by one flavor over another even if it is the same brand or type of drink. With the vast array of flavors and types (hypotonic, hypertonic and isotonic), there is no easy way to suggest one drink for every circumstance. That said, it is hard to argue against Mother Nature’s original sports drink—water. 

In the interest of full disclosure, the author uses sports drinks/rehydration supplements sparingly. I take a commercially available vitamin and mineral supplement with meals that are comprised of a protein, fibrous vegetable, and starchy carbohydrate. I generally carry a bottle of water in my patrol car and drink from it regularly. 

Due to shift work and personal taste, I regularly drink black coffee but forego carbonated drinks.  I use isotonic sports drinks when meals have been skipped on the same days that I have extended myself in hot environments (i.e., humid days of bicycle patrols, long outside instruction, or training days).

Martin Day is a sworn, full-time police officer in Southwest Ohio, part-time adjunct police academy instructor, Fit-Force© certified fitness coordinator, Ohio Peace Officer Training Commission Fitness Specialist and Subject Control instructor, Parrillo Performance Certified Personal Trainer, and an American Kettlebell Club Coach. He may be reached at

Published in Tactical Response, Jul/Aug 2013

Rating : 7.3



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