According to the CDC, 7,233 people have died from heat-related deaths over the past 11 years (658 per year on average), with 5,201 of those  being ruled as a direct result of heat exposure (1). While many of the individuals who died were aged 65 years old or older, every summer there are reminders that this isn’t simply an issue with the aging population. In 2017 there was the 16 year old from Riverdale, Florida.

In 2008 there was a 15 year old from Louisville. And many of you might remember the story of Korey Stringer, the 27 year old Pro Bowler from the Minnesota Vikings. These are a few of the examples of what has become a terrible recurrence: heat related deaths during summer practices. In order for this to happen, the body’s core temperature has to reach, and remain at or above, 106ºF.

Temperatures that high represent a catastrophic failure of a system that we, as humans, have evolved to a greater degree than any other animal on Earth. Our ability to thermoregulate…aka…maintain our body temperature, is critical for our survival. When you’re hot, you sweat. But In order to sweat, you gotta hydrate. But only the weak need water breaks, right? Quite the opposite, in fact. In this article, we’ll get you up to speed on the fallout of dehydration and effective strategies to ensure that your athletes are in the clear.

Running on Empty

Most of the early research in dehydration, or hypohydration (hypo = beneath/below), came from the wrestling community; rightfully so when you have athletes who lose, on average, 9-15% of their pre-season body weight in order to compete (2), with most of these cuts coming from a loss in total body water (3). As you can imagine, intentional dehydration results in a less than desirable outcome. Intuitively, dehydration will lead to a decrease in plasma volume, which leads to a lower stroke volume (amount of blood with each heartbeat), leading to an increased resting and exercising heart rate response.

We will call this an increase in cardiovascular strain (4, 5, 6). This increase in cardiac strain has a direct, negative impact on endurance capacity (7, 8). The reduced plasma volume will impair our ability to thermoregulate (5, 9). And, though not a direct impact on performance, this reduced volume can lead to decreased renal function or failure (10). But, what if your sport only requires 6 seconds of total work per competition? Or what if you live in 3-5 yard bursts of energy with 40 or so seconds of rest between each bout? What do power based athletes have to worry about?

Power Athletes and Hydration

There are three main components when it comes to performance in power based sports: muscular strength, power, and high-intensity endurance. It is through these lenses that we will take a glance at the effects of dehydration on the Power Athlete. A reduction in hydration of as little as 3% can elicit, on average, a reduction of 2% in overall strength. Not a huge deal, right? Your athlete that could squat 400 lbs, after sweating a bit, can still squat 392 lbs. But if you’ve made it this far into the article, you’re no idiot. You know it’s not just about strength, it’s about power!

Well now, at that same 3% dehydration you’re looking at about 17% less power (11) in knee extension, and 22% less total anaerobic power output (12). And repeated movements? How about a decrease in jumping height by 5% after only losing 1% total body water (13)?! Your team is a 4th quarter team? Not if they’re dehydrated. You prefer water cuts for your weightlifters? I guess you prefer leaving kilos on the platform too. You picking up what I’m putting down? So now what?

Strategies for Avoidance

The best step to ensuring your athletes remain properly hydrated would be to check them prior to training every day. There are advanced ways to do this (blood and/or urine analysis). But, unless you’re working at the professional level, you don’t have that kind of dough, coach. Fear not, we have you covered. Here are two *ALMOST* free means of helping your athletes be aware of their hydration status.

Weigh-in pre- and post-training:

Simply have your athletes step on the scale prior to and immediately following practice. This won’t let you assess their hydration status going IN to practice, but you can at least make up what you lost in that training session. This is more effective if you have a “heavy” sweater.

Electrolyte balance:

With sweat, your body loses electrolytes. The primary two electrolytes lost are sodium and chloride. Easiest way to battle this to have your athletes have a healthy salt intake. They don’t have to go full Efferding, but adding a bit to their meals throughout the day won’t hurt.

If you’re worried about your athlete’s hydration status, these two pointers may help them in understanding of their own hydration, and take ownership of it.

Bottom Line

As we sit in the thick of summer training, we simply cannot avoid the summer temperatures. The combination of heat and hard work will surely get your athletes sweating. Like nutrition, hydration and rehydration strategies should be a part of your holistic approach to empowering performance. You are now armed with the knowledge to suggests healthy options and avoid a decreased quality of training otherwise seen in athletes.

But, it still comes back to you, coach! Don’t be that guy/gal. Don’t try to instill “mental toughness” by withholding water breaks. Not only is that lazy, unoriginal coaching, it will also bring down your athlete’s in-training performance…and potentially at worst, kill them.

1. Heat-Related Deaths After an Extreme Heat Event — Four States, 2012, and United States, 1999–2009; https://www.cdc.gov/mmwr/pdf/wk/mm6222.pdf
2. Tipton, C. M., & Tcheng, T. K. (1970). Iowa wrestling study: weight loss in high school students. Jama, 214(7), 1269-1274.
3. Steen, S. N., & McKinney, S. (1986). Nutrition assessment of college wrestlers. The Physician and sportsmedicine, 14(11), 100-116.
4. Allen, T. E., Smith, D. P., & Miller, D. K. (1977). Hemodynamic response to submaximal exercise after dehydration and rehydration in high school wrestlers. Medicine and science in sports, 9(3), 159-163.
5. Sawka, M. N., Francesconi, R. P., Young, A. J., & Pandolf, K. B. (1984). Influence of hydration level and body fluids on exercise performance in the heat (No. USARIEM-M-11/84). ARMY RESEARCH INST OF ENVIRONMENTAL MEDICINE NATICK MA.
6. Vaccaro, P., Zauner, C. W., & Cade, J. R. (1976). Changes in body weight, hematocrit and plasma protein concentration due to dehydration and rehydration in wrestlers. The Journal of sports medicine and physical fitness, 16(1), 45.
7. Ribisl, P. M., & Herbert, W. G. (1970). Effects of rapid weight reduction and subsequent rehydration upon the physical working capacity of wrestlers. Research Quarterly. American Association for Health, Physical Education and Recreation, 41(4), 536-541.
8. Saltin, B. (1964). Aerobic and anaerobic work capacity after dehydration. Journal of Applied Physiology, 19(6), 1114-1118.
9. Saltin, B. (1964). Circulatory response to submaximal and maximal exercise after thermal dehydration. Journal of Applied Physiology, 19(6), 1125-1132.
10. Zambraski, E. J., Foster, D. T., Gross, P. M., & Tipton, C. M. (1976). Iowa wrestling study: weight loss and urinary profiles of collegiate wrestlers. Medicine and science in sports, 8(2), 105-108.
11. Viitasalo, J. T., Kyröläinen, H., Bosco, C., & Alen, M. (1987). Effects of rapid weight reduction on force production and vertical jumping height. International Journal of Sports Medicine, 8(04), 281-285.
12. Webster, S., Rutt, R., & Weltman, A. (1990). Physiological effects of a weight loss regimen practiced by college wrestlers. Medicine and Science in Sports and Exercise, 22(2), 229-234.

Hoffman, J. R., Stavsky, H., & Folk, B. (1995). The effect of water restriction on anaerobic power and vertical jumping height in basketball players. International Journal of Sports Medicine, 16(04), 214-218.

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