It's getting hot in here...

von Pascale Gränicher

Sultry nights, sticky ice cream hands, muddy brains - this is summer at its best.

It is hard to focus if the sun constantly burns down and sweat drips tireless from and to everywhere.

Heat waves are great when you have nothing else to do but to read a good book under a parasol, lie on a beach and sip a refreshing coconut. Yes… Oven-like offices and physio practices are definitely not the place to keep a cool head. It is hard to concentrate when your brain is busy coordinating body's own cooling processes instead of thinking about intelligent stuff or composing therapy programs for injured patients.

The number of work-related injuries seems to increase in hot weather. Due to physiological limitations (e.g. decreased blood flow, central fatigue), the ability to work decreases in temperatures above 26°C. Since concentration and motor skills can also be impaired, the risk of mistakes and accidents has been shown to increase in high temperatures. In addition, body core temperature rises, causing a shift from aerobic to anaerobic energy production. This means, muscles' energy stores empty much faster and we get tired and sluggish.
In summer, life takes place more outdoors and outdoor activities seem to encourage more accidents (apart from the under-the-parasol-book-reading-part).
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But there are also a few positive aspects of this hot summer – apart from the seamless tan and barbecue:

• Lots of vitamin D: Positive effect on sexual functioning in men, improvement of the immune system and regulation of the inflammatory response: Get outside
• Improved wound healing: Stem cell populations in the sweat glands seem to support the regeneration and repair of (scar) tissue: After surgery, it is okay to sweat
• Direct sunlight No. 1: Better mental health and higher work attitudes and satisfaction: Get outside
• Direct sunlight No. 2: Favourable effect on cardiovascular risk factors: Even if you suffer from heatwave stress, your blood pressure will remain cool (to a certain extent). A little sunbathing never hut anyone
• Sport performance: Improved top speed when sprinting. Don’t skip your workout – muscles like warm weather (only with sufficient water intake and preferably in the shade and not for too long)
• Being happy: Serotonin production in our brain is directly related to the amount of time spent in bright sunlight. Need a cheer up? Go outside!

What is decisive is how you deal with the hot situation – you, yourself and your patients or athletes. Important basics like drinking enough water and using sunscreen don't need to be repeated…
Remember: Your body and brain cool down in hot weather, so try to be cool, too.

References
Biedermann, T. et al. (2010). Human Eccrine Sweat Gland Cells Can Reconstitute a Stratified Epidermis. J Investig Dermatol; 130(8): 1996-2009
Holick, M.F. (2004). Sunlight and vitamin D for bone health and prevention of autoimmune diseases, cancers, and cardiovascular disease. Am J Clin Nutr; 80: 1678-1688.
Krysiak R, Szwajkosz, A. & Okopien, B. (2018). The effect of low vitamin D status on sexual functioning and depressive symptoms in apparently healthy men: a pilot study. Int J Impot Res; doi: 10.1038/s41443-018-0041-7. [Epub ahead of print]
Kjellstrom, T., Kovats, R.S., Lloyd S.J., et al. (2009). The direct impact of climat change on regional labor productivity. Arch Environ Occup Health; 64:217-227.
Lambert, G.W., Reid, C., Kaye, D.M., Jennings, G.L. & Esler, M.D. (2002). Effect of sunlight and season on serotonin turnover in the brain. Lancet; 360(9348):1840-1842.
Mihyang, A., Colarelli, S.M., O’Brien, K. & Boyaijan, M.E. (2016). Why We Need More Nature at Work: Effects of Natural Elements and Sunlight on Employee Mental Health and Work Attitudes. PLos One; 11(5): e0155614
Otte im Kampe, E., Kovats, S. & Hajat, S. (2016). Impact of high ambient temperature on unintentional injuries in high-income countries: a narrative systematic literature review. BJM Open; 11,6(2): e010399.
Sheng, R. et al. (2018). Does hot weather affect work-related injury? A case-crossover study in Guangzhou, China. Int J Hyg Environ Health; 221(3):423-428.

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