Hydration Strategies
With summer in full-swing and this heat wave rolling through, staying hydrated is vital to our health and physical performance yet proper hydration is often overlooked! Water helps to regulate body temperature, aids in digestion, and maintains many other bodily functions. Our bodies constantly expend water through sweat, breathing, and digestion, therefore monitoring hydration status throughout the day can make a big difference in day-to-day activities!
Our bodies are literally made up of water; water represents a larger percentage of body mass than any other substance! With that in mind, now you can understand how important hydration is for optimal health and well-being. Dehydration can be a scary and confusing concept to many, but the good news is that the majority of people do not need a specific hydration strategy due to the low volume of sweat loss experienced during a standard workout session. With that being said, there are scenarios where hydration advice can be pivotal in helping optimize physical performance…such as in the kind of high temperatures we are currently experiencing!
Physiology of Hydration: Around 2/3 of the fluid in the body is located inside of individual cells, called intracellular fluid(ICF); the rest can be found in the vascular system or in the space between cells, collectively called extracellular fluid(ECF). There are two electrolytes that help govern where body water will go: Sodium(NA+), which is the major ECF solute, and potassium(K+), which is the major ICF solute. You know how sports drinks advertise that they contain electrolytes? Well what exactly is an electrolyte? Electrolytes are molecules that contain a negative or positive charge; hence the plus sign you see after the atomic symbol (NA+, K+). The mechanism that regulates and dictates total body water levels and distribution of water to various body compartments is called osmolality. Our bodies have multiple sites that house osmoreceptors which detect shifts in osmolality and generate responses to return the body to fluid and sodium homeostasis. Fluid and electrolyte shifts in the body are caused by: Fluid gain (Food and Beverage intake), and Fluid Loss (Urine output during recovery and sweat loss during exercise). (Choosing a sports drink and figuring out if it’s actually necessary for you to consume those additional calories can be confusing, so schedule a consult with Plus Forte for guidance!)
Where does sweat come into play? Body temperature regulation during exercise is influenced by total-body water levels, but hydration status alone will not determine whether someone will experience a heat-related illness or heat stroke. Sweating provides the greatest cooling effect on the body, and earlier onset of sweating and an increase in sweat rate are important adaptations for improving tolerance to exercise in hot environments. The transformation of sweat from liquid to vapor produces this cooling effect. There are many elements that determine sweat evaporation rates: heat, humidity, convection—>refer to the infographic.
What makes you thirsty? A sensation of thirst is related to a loss of body water- sweating and urine production, resulting in decreased blood pressure due to a loss in total blood volume. Our bodies house receptors known as baroreceptors that detect these pressure changes and stimulate thirst drive. In typical conditions, total body water losses are minimal and severe thirst is generally not experienced without an intake of salty foods. Exercising in the heat can result in increased sweat rates BUT unfortunately the fluid loss from sweat does not always result in a sufficient thirst response, leading to inadequate fluid intake during recovery. This is why having a hydration strategy can be very important!
How does hydration status affect my performance? There are two major factors concerning athletic performance that hydration status can affect: cardiovascular and thermoregulatory function. The majority of thermoregulation attributed to body water in hot conditions comes from the production and evaporation of sweat. Half-marathon running studies conducted under hot environmental conditions demonstrated body temperature increases to greater than 104 degrees F despite lack of heat-related illness symptoms(Dion et al., 2013), and suggested that most endurance athletes will only replace 15 to 20% of their sweat losses during longer duration training bouts or competition(Lee et al., 2010). Exercising dehydrated results in upward drifts of heart rate and body temperature. The good news is that even if you begin exercising dehydrated, simply drinking to natural preference can be enough to offset the upward drift of HR and temperature(Armstrong et al., 1997). So, when in doubt, listen to your body and drink ad libitum to help ward off the potentially harmful effects of dehydration!
Want to develop a personalized hydration strategy that fits your training intensity, location, and schedule? Plus Forte can help you with that!
Reference: NASM. (n.d.). Lesson 1-4: Hydration. In Nutritional Science: Nutrition Certification.
