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Original articles  


The Journal of Sports Medicine and Physical Fitness 2000 March;40(1):35-40

language: English

The effects of an application of suncream on selected physiological variables during exercise in the heat

Connolly D. A. J., Wilcox A. R. *

From the Human Performance Laboratory Program in Physical Education University of Vermont, Burlington, USA
* Department of Exercise and Sport Science Oregon State University, Corvallis, USA


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Background. The pur­pose of ­this ­study was to inves­ti­gate the ­effects of an appli­ca­tion of sun­cream on ­mean ­skin tem­per­a­ture (MST), rec­tal tem­per­a­ture (Tre), oxy­gen con­sump­tion and ­heart ­rate dur­ing exer­cise in the ­heat.
Methods. Twenty-two ­male sub­jects under­went two ­steady ­state exer­cise ­tests (55% of max­i­mum oxy­gen con­sump­tion, ­mean ­work ­rate 153 ­watts) for 40 min­utes (fol­low­ing a 5 min­ute ­warm-up), ­under two treat­ment con­di­tions at the ­same ambi­ent tem­per­a­ture (32°C, 54% rel­a­tive humid­ity). One treat­ment ­involved wear­ing an appli­ca­tion of sun­cream (SC) ­while the oth­er treat­ment did not (NSC). Suncream was ­applied in the ­amount of 30 ml/m2 of ­body sur­face ­area.
Results. Results of ­this ­study indi­cat­ed ­that an appli­ca­tion of sun­cream sig­nif­i­cant­ly ­reduced MST, on aver­age. 31°C, dur­ing exer­cise in the ­heat (p=0.03). However, fur­ther sta­tis­ti­cal anal­y­sis ­revealed ­that ­this was a func­tion of a sig­nif­i­cant inter­ac­tion ­effect (p=0.001) (main ­effect is sun­screen; inter­ac­tion ­effect sun­screen ­plus tem­per­a­ture). MST was low­er for the SC con­di­tion ver­sus NSC ­over all ­time meas­ure­ments. Results ­also ­showed a sig­nif­i­cant dif­fer­ence in the ­mean ­core to ­skin tem­per­a­ture gra­di­ent (p=0.001), ­with a great­er gra­di­ent exist­ing in the SC con­di­tion. There did not ­appear to be any ­effect of sun­cream on ven­ti­la­tion, rec­tal tem­per­a­ture, oxy­gen con­sump­tion, lac­tate lev­els, ­sweat ­loss, per­cent plas­ma vol­ume ­change, rat­ing of per­ceived exer­tion, or res­pir­a­to­ry ­exchange ­ratio. Interestingly, ­although not sta­tis­ti­cal­ly sig­nif­i­cant (p=0.18), rec­tal tem­per­a­ture ­remained low­er, on aver­age 0.1°C, ­under the SC con­di­tion for eve­ry meas­ure­ment through­out the exer­cise ses­sion.
Conclusions. In con­clu­sion, ­results of ­this pre­lim­i­nary ­study sug­gest ­that an appli­ca­tion of sun­cream ­does not ­impair ­heat dis­si­pa­tion as indi­cat­ed by a ­decreased MST and ­increased ­core to ­skin ther­mal gra­di­ent.

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