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Blog / 2013 / May / The Science of Sweat
May 21, 2013

The Science of Sweat


Personal trainers, health coaches, group exercise instructors, and physical therapists all must be able to handle and address client concerns-such as a client that doesn't like to sweat. Every client will be different in how much they sweat and how much sweat they can tolerate. In order to provide support and guidance to your client, it's important to have a basic understanding of why we sweat. It's also important to have some sweat-related tips readily available to help clients "beat the heat."

Why Do We Sweat?

There are two types of sweat glands: eccrine and apocrine. The body has thousands of eccrine glands, which effectively regulate the body's temperature. As the body's temperature rises, the nervous system goes to work to stimulate the eccrine glands to release sweat. Sweat is made up of water, sodium and other substances that help cool the body down.

Apocrine glands are found mainly in the underarm and groin areas. Although the body's temperature can stimulate these glands, they are also triggered by stress, anxiety or fluctuating hormones. The apocrine glands produce bacteria that help break down the sweat, which causes body odor. That's why we just put deodorant under the arms rather than all over the body.

People have an average of two to four million sweat glands. But how much sweat is released by each gland is determined by many factors, including gender, genetics, environmental conditions, age or your fitness level. Two of the major contributors to sweat rate are an individual's fitness level and weight. If an individual weighs more, sweat rate is likely to increase because the body must exert more energy to function and there is more body mass to cool down.

On the other hand, a fit person will start sweating earlier and easier. It may sound strange at first but as someone becomes fit, the body becomes more efficient at regulating the body's temperature. When you start sweating earlier the body cools down faster, which releases extra body heat and allows you to work out harder for longer. Another theory suggests that during exercise, the body needs to pump more blood to the working muscles, which also stimulates the eccrine and apocrine glands.

Dealing With Sweat During Workouts

As trainers, it's important to encourage your clients not to use sweat as a weight loss tool. Increasing the level of sweating will not lead to a smaller waist size; but it can cause dehydration. Environmental heat and humidity can even have a negative effect on your client's ability to sweat.

Here are several tips that you can provide to your clients to help make sweating bearable and keep their workout efficient:

  • Wear sweat-wicking clothes. Wear clothes that are not skin-tight to allow the heat to move away from the body.
  • Pull up your hair and keep it dry. Having the neck and face clear of hair will help dry sweat cooling down the body faster. Wearing a head band to keep bangs off the face can also help.
  • Stay hydrated throughout the day. If you go into a workout dehydrated, your body won't be able to sweat as efficiently as it should. This causes an increase in body temperature, but limits the ability to sweat easily to cool the body back down. ACSM provides guidelines on how to stay hydrated.
  • Wash the hands, face and arms before a workout. Lotions and make-up can cause blocked sweat glands, which can cause irritation and heat rash.
  • Some suggest that removing excess hair from the armpits can reduce body odor caused by sweating since the hair traps in the bacteria and sweat.
  • If your client feels they sweat excessively, they can talk to their doctor about a condition called hyperhidrosis, which is a disorder of overactive nerves connected to the sweat glands, and causes sweating from normal activities.

Most importantly, listen to your client as they express their concerns and address them appropriately. Just because you like to sweat doesn't mean your client feels the same way. Determining what works on an individual basis, and educating clients on the science behind the sweat is key to developing a successful workout routine. For more information on excessive sweat, see 7 Signs of Excessive Underarm Sweat by Beth W. Orenstein.

Share your workout tips for dealing with sweat in the comments below. 

Julieann Hansen is an ACSM Certified Personal Trainer, Certified Yoga Instructor, Certified ACE Group Fitness Instructor, Certified Spin Instructor, Certified Workplace Wellness Specialist and has her Masters in Public Health. She has been in the fitness and wellness industry for nearly 10 years.  

She currently serves on the Exam Development Team for ACSM's Committee on Certification and Registry Boards (CCRB). Julieann writes for a few online magazines and blogs, including Livestrong.com and Patriots Fitness Magazine. Julieann currently works as the Wellness Specialist for Rocky Mountain Health Plans and loves helping employer groups implement their wellness programs. When Julieann isn't working, she loves music, the outdoors, and running.

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