Sweat rates vary by individuals and can be influenced by the fitness level of the worker, the intensity of activity, hydration status, environmental conditions (heat, humidity, etc.), and clothing. Sweat losses between approximately 300 ml (~10 oz) and 1000 ml (~34 oz) per hour have often been reported in the industrial athlete. Over an 8-hour work shift, this can mean a loss of up to 2 gallons of sweat.
Fluid lost through sweat, but not replaced through drinking leads to dehydration. In workers and athletes alike, dehydration can lead to a decrease in strength, a drop in endurance, and a reduction in motor skills.
Dehydration can also contribute to serious health and safety issues. Fluids not replaced can lead to feelings of fatigue and may inhibit cognitive (thinking) function. For many industrial athletes, loss of cognitive function, which can include slowed reaction time and poor decision making, may impact their physical safety as well as that of their colleagues.
Dehydration and Heat Illness: Warning Signs
Besides adversely affecting the performance and safety of workers, dehydration can also put individuals at a greater risk for heat illness. If the body is not able to clear the heat produced by the working muscles, core temperature can increase to unsafe levels. If the rise is too severe, heat illness may follow.
Heat illness can encompass heat cramps, heat exhaustion, or potentially deadly, heat stroke. Heat illnesses can progress from heat cramps to heat exhaustion to heat stroke, although a victim may not go through all stages and could quickly succumb to heat stroke. Common signs and symptoms for dehydration, heat exhaustion, and heat stroke include the following:
- Nausea or vomiting
- Decreased performance
- Heat sensations on head or neck
- Nausea or vomiting
- Decreased muscle coordination
- Heat sensations on head or neck
- Dry mouth
- Loss of balance/muscle function/collapse
- Elevated core temperature
Unfortunately, the signs and symptoms of heat exhaustion and heat stroke are not necessarily specific to each condition, nor is there a systematic order of appearance. If heat exhaustion is suspected, move the individual to a cool environment, remove excess clothing, elevate his or her legs, and provide fluids. The individual’s condition should improve fairly quickly.
However, heat stroke is a medical emergency requiring the individual to be cooled down as soon as possible. If heat stroke is suspected, contact emergency personnel immediately, but start the cooling process first.
Minimizing Dehydration and Heat Illness: Controlling the Risks Maintaining proper hydration can help reduce the risk of dehydration and heat illness. Arriving to your shift properly hydrated is the first step and drinking adequate fluids during the shift is the second step. To help your employees assess their hydration status, have them ask themselves 3 questions:
- Is my body weight notably less than it was yesterday?
- Is my urine dark in color?
- Am I thirsty?
If they answered "yes" to any or all of these questions, they may be dehydrated.
To help your employees stay on top of fluid losses, encourage them to drink the necessary fluid throughout their shift. To determine the amount of fluid an individual should consume to adequately replace sweat losses, they should weigh themselves before and after their shift. An inexpensive, but reliable digital scale placed in the locker rooms is an excellent tool for workers to track their hydration needs. If weight is lost during the shift, drink more fluids next time. If weight is gained, drink less. For every 1 pound of weight lost during a shift, the body is down approximately 16 oz of fluid.
Providing beverages with flavor and electrolytes, particularly sodium, can also help your workers stay hydrated. Compared with water, beverages with flavor and electrolytes have been shown to increase drinking. Consuming a sports drink, like Gatorade, may also aid hydration as it contains a small amount of sodium that helps maintain the level of sodium in the blood and reduces urine production. Research in occupation-simulated environments indicated workers stay better hydrated when they have access to a sports drink compared to water alone. Additional research has shown that the sodium in a sports drink like Gatorade poses no risk to blood pressure even when workers consumed up to a gallon of the beverage during 8-hour work shifts.
Other strategies that will help minimize dehydration and heat illness in the workplace include clothing options and breaks. While not possible for all industrial athletes, wearing light-colored, breathable clothing that allows sweat evaporation can help keep their core temperature down. If safety gear is required, be sure the employees remove as much of it as possible when in a safe area and if it is permitted. Also, be sure to provide frequent breaks, particularly when the environmental stress is high. This is a great time to seek a cool place for a nice cold beverage! By taking just a few simple precautions, you can help maintain the performance and safety of your industrial athletes.
Melissa Tippet is a scientist and Craig Horswill is a senior research scientist at the Gatorade Sports Science Institute. Both conduct research on hydration and heat stress in sports, exercise, and occupational work environments.