Instructor’s are usually not in control of the pool temperature of a facility. One of my most uncomfortable memories was someone screaming at me that the pool was too cool for them and could I turn up the temperature PLEASE #^^*? Did she realize what she was asking and how dense the water is? I not only had no idea where the temperature controls were, I knew changing the temperature would take much more than an hour to change in a 25 meter pool. And the bottom line - I was the newest member on the staff and had absolutely no power to make decisions on changing the temperature! I smiled and said that I would warm all of them up with my energetic class design.
The reality is that instructors do not have control over the temperature gauge and that most bigger pools may become even cooler with the cost of pool maintenance, cut backs, and yes, even more penny pinching (i.e. recession). We cannot always control the pool temperature; however, we can learn how to offer participants more comfort by understanding how to keep them moving to stay warm.
From facility to facility, season to season, time of day, back wash or a maintenance problem - pool temperature will ALWAYS be a challenge for us. Another complication is that everyone acclimatizes differently to the same water temperature. The reality is that some people may enjoy the cooler temperatures for the refreshment (for instance: menopausal women, exercising on hot and humid days, or the hypertensive person) while others may prefer warmer pool temperatures (especially if they are in pain or not able to generate more heat through muscle or movement). Understanding the science to design a balanced program as well as understanding the mechanisms of thermoregulation is critical to pool comfort.
Generally pools have temperatures of between 27 and 32 degrees Celsius or the equivalent 81-90 degrees Fahrenheit. Over 32 C or 90 F is considered a therapy pool may pose the opposite challenge of over heating.
The ideal pool temperature for regular aquatic exercise and providing a balanced program is between 28-29°C or 83-86°F.
Body composition largely determines how an individual thermo regulates. Muscle tissue heats you up and body fat insulates. Becoming cool or cold will illicit shivering which contracts or cramps the muscles and will accentuate pain and discomfort. Conversely overheating may be more dangerous as someone with cardiovascular diseases such as hypertension (1 in 3 adults have HBP, 1 in 4 children have HBP, and 1 of 2 women over 70 have HBP) may put their heart at risk and perhaps induce a stroke and risk to their heart.
Mechanism of Thermoregulation:
Why and How: Thermal regulation is the ability to maintain the body’s core temperature based on the balance between heat production and heat loss.
As shown in the illustration, body temperature, or the temperature of the deeper tissues or core is constantly trying to create a balance between the factors that add or subtract body heat. The balance is maintained by the integration of mechanisms that alter heat transfer to the periphery or shell, regulate evaporative cooling and vary the body’s rate of heat production (McArdle, William D, Exercise physiology: energy, nutrition and human performance, 3rd ed. 1991, pg. 547).
When exercising in a warm environment, heat is gained through active muscles and through heat being absorbed from the environment (air and water in the pool). Core temperature rises. Core temperature falls when heat is lost by conduction, convection and the vaporization of water from the skin and breathing.
Conduction: Heat moves from warmer to cooler regions during stationary muscle conditioning or flexibility exercises. Water temperature that is cooler than your body temperature, gives you a sense of being cooler because heat is moving away from your body and into the pool water. This is heat loss by conduction.
Convection: Cool water is exchanged for warm water close to your skin. Body movement causes water to be continually replaced by cooler water. This is heat is loss by convection. In 2006, research done by Data and his group proved that the rate of heat loss from the body is further accelerated, due to convection, when water is moving around the subject as happens during aquatic exercises.
Vaporization: Heat evaporates from the body as sweat because the air is cooler than your skin temperature.
When participants get into the pool, the water will generally feel cool to the body because of the difference between body temperature (98.6 degrees) and the lower water temperature. As the program begins the exerciser becomes warmer usually within 2- 3 minutes. The core temperature rises because moving and using the legs to generate heat will warm up the body. Research suggests 4.2 METS (such as the energy required for a moderate walk ) will thermal regulate someone in 84 F/29 C H20 temperature. The instructor needs to move throughout the warm up and to provide a gradual increase in intensity as well as an active range of motion and preparation for the workout. As the class progresses into the conditioning segment, an instructor should alternate cardiovascular conditioning for warmth (keeping the legs moving generates heat) with muscle conditioning where the body may cool and core temperature decreases due to less movement. The instructor needs to train muscular strength and flexibility to balance the program as well as increase the exercisers lean muscles mass which contributes to the ability to sustain duration and intensity for cardiovascular performance. Only doing cardiovascular movements will not provide a balance program nor a system to increase lean muscle mass and muscular fitness.
To maintain thermal regulation throughout an aquatic program it is critical to alternate active movement with lesser intensity. The goal for every program is that a participant remains comfortable throughout – i.e. they never become either too cool or too overheated.
Just as we need to keep participants warm and happy, realize that working in a pool that is too warm also has its drawbacks. Overheating is detrimental especially for anyone with a cardiovascular problem or High Blood Pressure. Did you know that 1 in 3 adults, 1 in 4 children and 1 out of 2 women over 70 have high blood pressure? Yes, high blood pressure is that prevalent! So doing too much in a warm pool can place these participants at risk. It is critical to thermal regulate or balance the core temperature for safety.
The Warm Down portion of the program (notice that we do not say cool down) is intended to help relax the exerciser, re-stretch the tight musculature and gradually lower heart rate. Additionally the warm down provides a method to bring participants safely back to land and gravity. This point in the program is usually where there is less movement for the exercise and the core temperature falls. To prevent cooling to the point of shivering, the warm down should encompass some active stretching or providing filler movements in between the static stretches. This allows exerciser to remain thermal regulated and will get out of the pool while still warm.
Checklist for programming:
· Who is the exercise program for? Apparently healthy people or those with an assortment of medical conditions?
· What is the purpose of the exercise program? High Intensity, gentle fitness or a mixture of both?
· What is the temperature of the pool?
Remember: Participants need to develop appropriate levels of muscular strength and endurance FIRST to be able to move effectively through the water. Incorporating muscle work into a program will create the required strength to move effectively to generate heat and stay warm throughout the program. Additionally, muscle conditioning is critical to supporting the integrity of the joints.
FYI – Researchers found: body heat moves through water quicker than it does through air! The rate at which heat flows through water (thermal conductivity) is 26 times greater than air. The rate at which heat flows through the body is 4 times greater than air (Wilmore & Costill, 1994).
Research has proven that heat loss is reduced by wearing appropriate clothing (Kang, 1983; Wakabayashi, 2006).
Wearing items for warmth will greatly help to insulate the body. WaterART offers products such as: thermal vests, a ball cap, aquatic mitts, water shirts, shorts/ jammers/capris/leggings, full shoe or body suits.
We recommend patrons “layer” on their clothing (and layer off when they are warmer or have properly thermal regulated). All water wear should be made of endurance fabrics such as 1005% polyester because this fabric does not damage the pool filter and lasts longer. Additionally, this fabric resists shrinkage or losing its shape, resists odor and dries quickly because of the built-in ventilation. The new polyester is a great wave of the future because not only does this fabric machine wash easily – it feels great on your skin and should ( with proper care and pool chemical balance) last for years (not months).
Prepared by Julie Twynham & Rikki Gross
More information on Thermal Vests
More information on Water Wear