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Determining Your Sweat Rate

The goal of this test is to see exactly how much fluid loss (dehydration) is occurring to you during your training sessions or competition. This sweat rate is specific to you and how your body deals with temperature control, within given environmental conditions, during a specific exercise/sport and at specific intensities. Once you know this you will be able to determine your hourly fluid replacement needs for optimal rehydration and thus minimizing one of the greatest factors for poor performance.

Note: Increases in air temperature, humidity and exercise intensity will individually increase the amount of fluid loss, therefore will increase the amount of fluid needed to be taken in to rehydrate. Additionally your fitness level can also affect how much you sweat, with some elite athletes sweating considerably more than your average competitor. It is recommended that the test be completed over a variety of conditions and across each sporting discipline (for multi sport athletes) so that the data is as accurate as possible.

How to complete the Test

1. Empty you bladder, then weigh yourself holding your full water bottle (of which you will consume all or part of during the session) and record your weight (nude or swim suit) prior to the session. Do not consume any food or additional fluids after you have weighed yourself, until you have finished your test and reweighed yourself post workout (other than from your water bottle which you were weighed with). Select the units of weight, pounds or kilograms. Enter the results Pre-exercise weight in (A) in the calculator.
2. Complete a 1 hour workout at a given intensity, and drink like you normally would. Note the intensity level eg easy, moderate, hard as well as the air temperature and if possible the humidity.
3. Once you have finished your workout, towel dry, empty your bladder and then record your weight  (nude or swim suit) holding your water bottle with whatever fluid is left in it even if empty. Enter the result Post-exercise weight in (B) in the calculator.

You will now see the fluid loss in weight and fluid measurement, along with the percentage of body weight you have lost. Refer to the “Dehydration and Heat Stress” Table below to understand the impact of this on your performance.

There is a recommended fluid intake per hour listed at the bottom of the table, which relates to the specific conditions the test was undertaken in, therefore any increase in intensity, temperature or humidity would potentially increase the amount of fluids per hour required.

Dehydration and Heat Stress Table

% Body Weight Loss	Estimated % Performance Drop	Normal Temperatures	High Temperatures and/or Strenuous Exercise
1-2%	5-10%	Impaired Judgement, Irritability, Headache, Muscular Aches	Sweating, Flushed Face
3%	15%	Thirst Reflex Initiated, Sense of Fatigue, Tight Sore Muscles, Increased effects of 1-2% Symptoms	Profuse Sweating, Noticeably (to others) Impaired Judgement and Confusion
4-6%	25-35%	Profound Thirst, Dizziness, Muscle Cramps, Weakness, Fatigue	Very Irritable, May Act Irrational, Pale, Severe Headache Especially at Base of Skull
7-8%	40-45%	Nausea, Vomiting, Severe Vertigo or Dizziness, Somewhat Irrational, Severe Muscle Cramps, Staggering	Cold, Clammy Skin even though Core Body Temperature may be 104 o F or higher, May Have Stopped Sweating
9-10%	50-55%	Collapse, Very Irrational, Unconscious	Skin Pale, Cold and Clammy, Stopped Sweating, Muscles Tense & Contracted, Pupils Normal or Dilated, Pulse Weak and Rapid, Low Blood Pressure, Respiration Shallow
8-10%+	45-55%	Heat Stroke. Skin temperature may be 102-104 o F and the core temperature may be over 108 o F which, if prolonged, will lead to kidney failure and death.	Heat Stroke Skin Red, Dry, & Hot, Sweating has Stopped, Severe Headache, Extremely Weak, Numbness and Tingling in Extremities, Muscles Tense and Convulsive, Confusion, Dark Urine (if any), Pupils Contracted, Pulse Strong and Bounding,Rapid/Shallow/Labored Respiration, Delirious, Unconscious, Comatose