Sweat, Sun and Fun Pt. 2

Sweat, Sun and Fun Pt. 2

The peak summer heat and humidity is upon us. Workout intensity continues to increase. The AC at the office is broken. The ceiling fan is clicking on high.

As for maintaining thermoregulation, extreme environmental conditions bear an entire new level of difficulty (1). This is why we often hear of heat-

related illnesses during the summer (e.g. heat cramps, heat exhaustion, heat stroke).

As we discussed when busting last week’s sweat myth – our first adaptation to exercise is to sweat sooner.

Our bodies are pretty picky. They want to maintain a narrow homeostatic body temperature of 98.6 F.  When we exercise, several powerful physiological mechanisms of heat loss kick in to prevent an excessive rise in core body temperature (2)

Throw heat and humidity into the mix. This only adds to the challenge exercise already imposes on the human thermoregulatory system. Humidity is the equivalent of the skin’s worst sinus infection – congested with moisture from sweat with nowhere to go. With high temperatures present, the failure to dissipate internal heat causes the body temperature to rise even more. These conditions impair heat exchange between the body and environment. Pushing through the last set of prisoner push-ups is enough, now you’re forced to combat the heat too!

Good news – our body refuses to take ‘no’ for an answer. Give us heat, we take it on like a champ; adapting to deal with the environment wherever we go.

In just 10-14 days you’ve already adapted (most of which occurs in the first five days) (3)!

In the meantime, a few things happened making you better than ever …

• Increase plasma volumes: No more hot temperatures taxing us as before (it’s hard work trying to stay at 98.6 F) AND we don’t require as much fluid (4)
• Sweat earlier and faster: Less heat storage that would demand more fluid replacement (3)(6)
• Reduce the amount of electrolytes lost in sweat: Remember, efficiency. We need these for other processes!
• Reduce blood flow to the skin: Blood can go to other areas like your muscles…which trust me, you need (7)

The next brutal day when you’re hiking through the Pamulaklakin Forest, trapped in a house that feels like your college dorm from the ‘50s, and braving a lunch break power walk in a full suit – take your mind off the heat and embrace the changes your body is making.

You would feel much worse if you weren’t sweating…kind of like what happens when dehydrated…

Check back next week to see how it’s related!

References:

1. International Olympic Committee consensus statement on thermoregulatory and altitude challenges for high-level athletes. M. F. Bergeron, R. Bahr, P. Bärtsch, L. Bourdon, J. A.. L. Calbet, K. H. Carlsen, O. Castagna, J. González-Alonso, C. Lundby, R. J. Maughan, et al. Br J Sports Med. 2012 September; 46(11): 770–779. Published online 2012 June 9. doi: 10.1136/bjsports-2012-091296
2. Temperature regulation during exercise. M. GleesonInt J Sports Med. 1998 June; 19 (Suppl 2): S96–S99. doi: 10.1055/s-2007-971967
3. Acclimatization strategies–preparing for exercise in the heat. Y. Shapiro, D. Moran, Y. Epstein Int J Sports Med. 1998 June; 19 (Suppl 2): S161–S163. doi: 10.1055/s-2007-971986
4. Powers, S. K, Howley, E. T  (2012). Exercise Physiology: Theory and Application to Fitness and Performance. New York: McGraw-Hill Humanities/Social Sciences/Languages.
5. Exercise in the heat: challenges and opportunities. Ron Maughan, Susan Shirreffs. Sports Sci. 2004 October; 22(10): 917–927. doi: 10.1080/02640410400005909
6. Effects of training, environment, and host factors on the sweating response to exercise. L. E. Armstrong, C. M. Maresh. Int J Sports Med. 1998 June; 19 (Suppl 2): S103–S105. doi: 10.1055/s-2007-971969
7. Control of skin circulation during exercise and heat stress. M. F. Roberts, C. B. Wenger. Med Sci Sports. 1979 Spring; 11(1): 36–41.

Sweat, Sun and Fun Pt. 1

Sweat, Sun and Fun Pt. 1

Myth: Unfit people sweat more

Many assume that sweating is a sign of exertion, failure to respond to exercise, or lack of fitness. In fact, it’s the exact opposite – what’s concerning is NOT sweating.

Sweating is our response to any physical demand – it says “Hey, this is hard, but it’s all good because I know how to deal with it!”

At rest, your metabolic rate (how fast your body uses energy, which produces heat) is low. You aren’t doing much and your body can easily get rid of heat. However, start movin’ and groovin’ and your metabolic rate spikes. You’re burnin’ more energy! …and it’s going to take more than radiation to get all this heat out of your body. You need to cool down fast!

While you can handle the heat, your body isn’t having it. You are forced to switch gears and rely on cooling down (thermoregulation) a bit differently than before – evaporation (1).

In other words, sweating.

Now, each individual responds differently. Training adaptations and fitness are both factors in the sufficiency of sweating mechanisms, and subsequent need for fluid replacement. However, one thing’s for sure – with some training, an athlete achieves a better maintenance of body temperature (2).

This is at the expense of an increased sweat rate.

Remember: More sweat, more evaporative heat loss (this is the way we get rid of heat when exercising or else we would burn up). Our first adaptation to exercise is to sweat sooner (3). We are forced to become more efficient, and as a result improve thermoregulation.

Faster sweat →  more sweat →  more sweat on your skin that can’t evaporate → and more sweat that drips wastefully from the skin…as you notice when exercising (4).

While this isn’t pretty, it’s a more efficient adaptation. We are always looking for ways to do everything better and faster. If sweating and burning energy is what it takes for me to work out stronger and not feel sick, I’ll take it!

What this really means is that fit people are just more efficient sweaters (5). In most cases, our body’s first physiological response to being more efficient is to sweat more. As always, this varies person to person – some will respond in other ways.

In some cases, you will have people who sweat a ton but are extremely inefficient. Regardless, if you are sweating you are doing something right. So next time you leave the gym looking like you just hopped out of the pool, give yourself a pat on the back and rock it!

Look out for Part 2 of this series next week to see what happens when we start to heat things up!

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References

1. Thermoregulation during exercise in the heat: strategies for maintaining health and performance. Daniël Wendt, Luc J. C. van Loon, Wouter D. van Marken Lichtenbelt.Sports Med. 2007; 37(8): 669–682.
2. Long Distance Runners Present Upregulated Sweating Responses than Sedentary CounterpartsLee, J.-B., Kim, T.-W., Min, Y.-K., & Yang, H.-M. (2014). PLoS ONE, 9(4), e93976. doi:10.1371/journal.pone.0093976
3. Sex differences in the effects of physical training on sweat gland responses during a graded exercise.Ichinose-Kuwahara T1, Inoue Y, Iseki Y, Hara S, Ogura Y, Kondo N. Exp Physiol. 2010 Oct;95(10):1026-32. doi: 10.1113/expphysiol.2010.053710. Epub 2010 Aug 9.
4. American College of Sports Medicine (1996). Position Stand on Exercise and Fluid Replacement. Med. Sci. Sports Exerc. 28(1): i–vii.
   Control of skin circulation during exercise and heat stress. M. F. Roberts, C. B. Wenger. Med Sci Sports. 1979 Spring; 11(1): 36–41.