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Splish, Splash, Are We Back in Class?





      By Ashley Casto & Kaitlyn Rexroady  




As many of us have been confined indoors throughout the cold winter months, aquatic class participants are eager to return to the outdoor pools! A lapse in class participation is difficult for many exercise enthusiasts during the winter months. Many find themselves lacking social engagement, physical activity, much needed energy, and a healthy lifestyle. As participants are anticipating the opportunity to rejoin their outdoor pool classes around the world, the question arises, “When is it too cold to exercise in the water?”

This decision must be made based on safety concerns regarding how the cold weather affects the physiological processes, causing safety risks and health concerns to arise. There are numerous reasons that factor into this decision, such as safe water temperatures and air temperatures. We decided to “dive” right into this subject in order to keep you informed!

Water Temperature

Water temperature is a very important component to any aquatic class, and the American Red Cross recommends different water temperatures for varying facility activities. These activities and their respective temperature ranges are as follows according to the Pool & Spa Operator Handbook (2017): “recreational aquatic classes/sessions (82℉)*, aquatic sessions for infant/preschool children (90-93℉), children swimming programs (84-89℉), competitive swimming sessions (77-82℉), and spa areas (≤104℉)”.

*AEA recommends 83-86℉ for most aquatic fitness classes.  You can download the AEA Aquatic Fitness Programming Standards & Guidelines here, https://aeawave.org/Education/AEA-Protocols.


These temperature ranges serve to provide the most comfort for participants throughout their sessions, keep the muscles warm, as well as allow for optimal breathing patterns. This is not the only purpose, however, as prime water temperatures also allow for the proper function of pool chemicals. If temperatures are maintained within these ranges, then the chemicals used to disinfect the water will function properly. When the temperatures are too low, chemicals (i.e., chlorine) will have difficulty dissolving. On the other hand, if water temperatures are too hot then the chemicals will react too quickly, and more will need to be added to the water. Maintaining adequate chemical levels is key to a safe swimming environment, therefore, it is imperative to balance the pool water in order to avoid hazardous conditions. 

Everyone will react differently to colder water temperatures and acclimation will also contribute to one’s levels of tolerance. The term “acclimation” refers to one’s ability to adjust to altered temperatures in their surroundings. Therefore, someone can train their body to better tolerate colder temperatures in order to maintain normal bodily functions. Below is a table that describes, generally, how differing temperatures affect the body.

Water Temperature () Response
>77 77-82℉ is a comfortable temperature for competitive swimming. Temperatures around 80℉ or higher are typically desired for children and older adults.  Additionally, in waist depth or deeper water, warmer water temperatures increase the thermal load on the cardiovascular system yielding an increase in heart rate. 
<77 Changes within the body can begin at this temperature. For example, one may begin to experience slightly altered breathing.  Sympathetic nervous system activity begins to increase at lower water temperatures, which can accelerate heart rate, widen bronchial passages, constrict blood vessels, cause piloerection (goose bumps), and raise blood pressure.  

Breathing patterns are further affected. It may become more strenuous to control/hold one’s breath. There is also less thermal stress on the cardiovascular system.  Additional metabolic demands have also been noted during water immersion at or below 68 °F (20 °C), although heart rate and blood pressure responses remain unchanged.  It has also been noted that this lower water temperature will stimulate increased food consumption following immersion. 


“Swimming in temperatures below 70 degrees Fahrenheit can lead to increased heart rate and blood pressure. Risk, particularly for cardiac arrest, continues to increase in water under 64 degrees Fahrenheit, which is why many regulatory bodies require wetsuits when these conditions apply to an open water competition.” - US Master Swimming

50-60 This is a very dangerous temperature range for controlled breathing; this is where cold shock can occur. At this range, one loses their ability to control their breathing pattern and hypothermia can become a concern.  In addition to breathing, quick and/or powerful movements are impaired and total work ability is reduced.
<40 This water temperature is extremely dangerous. Similar to the 50-60℉ range, breathing control is nonexistent and the water can feel unbearable to the skin. 

Table 1. Various Water Temperatures and Their Impact on Breathing, information was gathered from the National Center for Cold Water Safety (n.d.),  Dixon et al, Šrámek et. al, Alshak et al, White et.al., US Masters Swimming, and Gleim et. al.

Air Temperature

For indoor pools, air temperature and humidity are much easier to maintain at a constant or alter at your leisure. The air humidity of an indoor pool is modified for the participants’ comfort and safety in addition to proper water balance within the pool. If humidity is too low, evaporation will occur and alter the water chemicals. Ample controls are set up for the facility to allow cooling and heating; set temperatures to be easily regulated by the staff. The ideal temperature range for the pool is predetermined and the range is to be strictly maintained. These are constantly monitored and adapted to the pool programming.

In terms of outdoor pools, Mother Nature often throws in a gust of wind, a beam of sunshine, a sprinkle of rain, a warm humid day, or a burst of arctic air with snowflakes into the setting. With each season bringing unpredictable weather, it is difficult to coordinate proper programming for the aquatic sessions. According to the Aquatic Exercise Association (n.d.), air temperatures in the outdoors cannot be regulated thoroughly, but limits are predetermined by the population involved in each program as well as the purpose of the class. However, for indoor temperatures the Aquatic Exercise Association (n.d.) recommends the air temperature in the aquatic facility be kept “between 75-85℉ with humidity between 50-60%” to avoid evaporating pool water. Therefore, it is presumed that ideal temperatures outdoors be modified versions of these limitations while accounting for the climate’s effects on the pool participants and their health conditions.

Health Conditions & the Cold Outdoors

There are many health conditions that coincide with swimmers and aquatic exercise participants in cold outdoor environments. A few of the most typical health conditions include hypothermia, frostbite, and respiratory tract infections. Hypothermia occurs when individuals are exposed to low temperatures for long periods of time. As the body loses heat to the surrounding cold water, the body begins to slow and alter the brain’s ability to critically consider the danger of the situation (CDC 2019).

Frostbite is a more severe reaction as a result of exposure to cold environments. This freezing condition inflicts a numbing sensation that can cause irreversible damage on the body that changes color and may, in the most critical cases, result in the possibility of an amputation of the exposed part of the body. A respiratory tract infection (RTI) is a disease that can occur in either the upper or lower regions of the respiratory tract. It has been noted that there is an increase in RTIs during the winter months due to the vasculature tightening and constricting from contact with the cold air (Mourtzoukou and Falagas, 2007). As a result, the body has a decreased defense to pathogens and is likely to incur greater risk of illness.  


Exercising is a very important component when it comes to promoting and living a healthy lifestyle. Moreover, it is equally vital to choose a form of physical activity that will pique one’s interest, thus ensuring that they stay engaged in the session.

So, when are water and air temperatures safe for aquatic exercise? There are a few factors that must be considered, especially in outdoor pools. First, is the pool heated? As water temperatures drop below 77℉, the sympathetic nervous system becomes more engaged in the ability to control breathing, altering metabolic responses, and the urge to consume more calories. This may not seem initially problematic, but can become an issue if the clients have prior health conditions or if the session becomes too vigorous. Furthermore, variations in water temperature will impact the effectiveness of the pool chemicals. If left unmonitored, this could create hazardous conditions for those in and around the facility. 

No matter if the pool is heated or unheated, air temperature and humidity will play a factor in outdoor sessions. If the air is less humid, the pool will undergo an increased amount of evaporation, ultimately leading to a decrease in water temperature as heat is lost through this process. General recommendations suggest keeping indoor facilities around a 50-60% humidity level, with air temperatures above 75℉. Therefore, we would want to aim for similar conditions outside, whenever possible. Keeping this in mind, it may be beneficial to begin outdoor classes when the temperature and humidity are consistently above/around these ranges.

When trying to determine the best start and end dates for outdoor aquatic sessions, as well as when it would be prudent to cancel a class, we must consider all of these factors, and the impact the conditions will have on one’s overall health.



Alshak MN, M Das J. Neuroanatomy, Sympathetic Nervous System. [Updated 2020 Jul 27]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2020 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK542195/

Aquatic Exercise Association (n.d.). Aquatic Fitness Programming Standards and Guidelines. Retrieved from https://aeawave.org/Portals/0/AEA_Cert_Docs/AEA_Standards_Guidlines_2020.pdf?ver=2019-12-18-131623-417×tamp=1576696862726

Bergen, K. 2019.  What’s a Safe Pool Temperature? https://www.usms.org/fitness-and-training/articles-and-videos/articles/whats-a-safe-pool-temperature

Center for Disease Control and Prevention. February 8th, 2019. Hypothermia|winter weather. Retrieved from https://www.cdc.gov/disasters/winter/staysafe/hypothermia.html

Dixon PG, Kraemer WJ, Volek JS, Howard RL, Gomez AL, Comstock BA, Dunn-Lewis C, Fragala MS, Hooper DR, Häkkinen K, Maresh CM. The impact of cold-water immersion on power production in the vertical jump and the benefits of a dynamic exercise warm-up. J Strength Cond Res. 2010 Dec;24(12):3313-7. doi: 10.1519/JSC.0b013e3181f212e2. PMID: 21068679.

Gleim GW, Nicholas JA. Metabolic costs and heart rate responses to treadmill walking in water at different depths and temperatures. The American Journal of Sports Medicine. 1989;17(2):248-252. doi:10.1177/036354658901700216

Mourtzoukou EG, Falagas ME. September 2007. Exposure to cold and respiratory tract infections. Int J Tuberc Lung Dis. 11(9):938-43. PMID: 17705968.

National Center for Cold Water Safety. (n.d.). What is cold water? Retrieved from http://www.coldwatersafety.org/WhatIsCold.html

Pool & Spa Operator Handbook. 2017. National Swimming Pool Foundation. Colorado Springs, CO.

Šrámek, P., Šimečková, M., Janský, L., Šavlíková, J., & Vybíral, S. (2000). Human physiological responses to immersion into water of different temperatures. European journal of applied physiology, 81(5), 436-442.

White, L. J., Dressendorfer, R. H., Holland, E., McCoy, S. C., & Ferguson, M. A. 2005. Increased caloric intake soon after exercise in cold water. International journal of sport nutrition and exercise metabolism, 15(1), 38-47.


Ashley Casto is a senior undergraduate student at West Virginia University. She is majoring in exercise physiology, minoring in sports and exercise psychology, and emphasizing in aquatic therapy. She will continue her education at West Virginia University to obtain her doctor of physical therapy degree. Ashley’s aquatic fitness credentials include AEA Aquatic Fitness Professional, AEA Arthritis Foundation Program Leader, and Certified Pool Operator certifications.

Kaitlyn Rexroad is a senior at West Virginia University and she is pursuing a Bachelor of Science in exercise physiology. Additionally, she will graduate with an emphasis in aquatic therapy. Kaitlyn has obtained many aquatic certifications throughout her time in the program, these are as follows: AEA Arthritis Foundation Program Leader, Certified Pool Operator, and AEA Aquatic Fitness Professional. She has been accepted into The Ohio State University College of Optometry to further her professional education.

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