Will a suntan make you FASTER (part 2)
WHY SUNSCREEN? - SUNBURN is an AVOIDABLE INJURY
Sometimes people find the wearing of sunscreen unpleasant when sweating and sometimes justify the abstinence of sunscreen because of a perception that it may interfere with normal sweating and thermoregulation (Ouyang & Schmalenberg, 2015).
Others are caught out by unexpected changes in weather, a failure to appreciate the sun strength, especially at altitude or just the logistical challenges of sport.
Even the best can be caught out, in 2014 multiple Tour de France winner Chris Froome suffered severe sunburn whilst training in an experimental mesh backed skinsuit with little UV protection (Wynn, 2014). If Froome had suffered the same injury during competition the additional stress and consequential effects on sleep quality in addition to possible impaired thermoregulation would undoubtedly have adversely affected his performance.
Sunburn is an avoidable injury
Most people are aware of the potential chronic health risks from sunburn, but it is also worth considering that sunburn is an inflammatory condition placing additional stress on the body. This additional stress will compromise the body’s ability to adapt to training.
Prevention really is the best option.
Whilst many options have been used to treat sunburn, researchers warn that there is no way to reverse damage to epidermal cells (Han & Maibach, 2004). In their 2004 review of treatment options Han and Maibach reported that the most effective practical approach to sunburn was to treat the pain, redness and swelling with emollient creams and anti-inflammatory pain killers.
An interesting development in sunburn remedies was reported in the Journal of Investigative Dermatology (Scott et al., 2017). In this double-blind placebo-controlled study, huge doses of vitamin D given one hour after a UV lamp burn where shown to significantly reduce skin reddening and inflammation.
“It is worthwhile to conjecture that vitamin D3 may provide an ‘endocrine barrier’ within the skin, utilizing energy derived from sunlight to reduce inflammation, and promote wound healing, tissue repair, and an enhanced epidermal barrier”.
Whilst it would be difficult to advocate the huge doses of vitamin D used in this study without medical supervision the proposed mechanisms suggest it may actually be sensible to optimize vitamin D levels before periods of increased sun exposure (Bikle 2017).
Vitamin D Paradox
Whilst the importance of sun exposure for normal vitamin D production is well known, the risks associated with UV skin damage caused by over exposure to sunlight can be serious. This limits the practicality of relying on annual vacations to binge on sun exposure in the hope of optimizing vitamin D levels. In a 2013 review on photoprotection and vitamin D, Kannan & Lim (2014) suggested that supplementation with vitamin D or vitamin D fortified foods was preferable to prolonged UV exposure to maintain proper serum levels.
Experts continue to stress the importance of using sun screen to protect against the negative consequences of sun exposure, this is especially important in periods of intense sun exposure typical of an annual vacation.
Whilst sun exposure can increase vitamin D levels, the dangers UV damage mean it is not a sound reason to avoid sunscreen. This is especially true in periods of intermittent intense sun exposure typical of an annual vacation.
In a recent review on photoprotection and vitamin D, Kannan & Lim suggested that oral intake of vitamin D supplements or fortified food was recommended over UV exposure to maintain optimal serum levels (Kannan +Lim 2013).
Whilst sunscreens applied at recommended concentrations of 2 gm/cm2 does reduce vitamin D synthesis in practical in-use settings sunscreen application has not been shown to have a detrimental effect on plasma vitamin D levels.
For those familiar with the anti-inflammatory effects of omega-3 fish oils it is perhaps unsurprising to find a link between fish oil consumption and sunburn. Researchers from the University of Liverpool reported in the mid 1990’s that dietary fish oil rich in omega3- fatty acids markedly reduced the sunburn response (Rhodes et al 1995).
In particular they were interested in the effects of fish supplementation on Polymorphic light eruption , fairly common skin rash cause by sun or artificial UV light exposure in those that have developed a sensitivity. This study involved patients taking a hefty dose of fish oil, 1.8g EPA; 1.2g DHA for 3 months. They were able to demonstrate that this dose of fish oil was effective in reducing the sensitivity of skin to this inflammatory disease process in addition to increasing resistance to sunburn.
Once consumed omega-3 fatty acids are incorporated into the phospholipids within skin and increase the ratio of omega-3 to omega-6. A typical western diet tends to be short on omega-3 fats and high in proinflammatory omega-6. It was suggested that increasing this ratio could modify the inflammatory response in addition to omega-3 acting as an oxidizable buffer. Omega-3 fats are easily oxidised and by ‘soaking up’ free radicals caused by UV exposure they may protect more critical structures from free radical damage. Due to the mode of action these authors also speculated that omega-3 may have a role in protecting from UV induced skin cancers.
This speculation finds support in more recent epidemiological studies that demonstrate a consistent tendency for reduced squamous cell skin cancer risk with higher omega-3 fatty acid consumption and a lower risk of melanoma development with higher consumption of fish oil (cited from Huang et al 2018).
Consideration of dietary consumption of omega-3 fatty acids to induce a healthy omega-3 to 6 ratio is likely to bring about numerous health benefits. Increased protection from the potential negative consequences of sun exposure is another good reason to optimise this area of diet.
Those concerned with photoaging and longer-term skin health should be aware of adventitious sun exposure, especially when travelling in vehicles and planes. Whilst vehicle widows block a significant amount of UV radiation they transmit a significant amount of damaging UVA. Several studies have demonstrated greater UV damage and incidence of skin cancers on the drivers’ side of faces which are more exposed to solar radiation (Paulson et al 2012). It may be good practice therefor to use a sunscreen with a good UVA filter when travelling on a regular basis.
JUST TO MAKE THIS REAL;- This author recently had treatment for a solar keratoses
on the right-hand side of the face – probably due to high UV exposure as a UK car driver. At a similar time, a friend suffered a similar but more serious condition on the left-hand side of the face. At first this was thought strange until it was realised that this driver had spent a considerable amount of time driving left hand drive vehicles on the continent.
Apply Sunscreen Regularly
Recent reports in the press have highlighted a WHICH survey (Fletcher, 2016) suggested that many once a day sunscreens lose up to 74% of their effectiveness after 6-8 hours. Clearly, this is still significantly more protection that if no sunscreen was applied at all and obviously it is not always practical to stop in the middle of an event to reapply sunscreen! However, a quick stop during training may be worth considering for those long training days, especially when it’s tempting to chat at the coffee stop for a little longer than usual.
Can Sunscreens impair thermoregulation and performance?
Some practitioners have questioned the use of sunscreen and other topical creams for use during exercise hypothesizing that they may reduce evaporative cooling via sweat. Some support for this stand can be found in a 1984 study which showed that sun screen usage resulted in a higher mean skin temperature, than in a no sun screen condition, in a short exercise test (Wells, Jessup & Langlotz, 1984) Higher skin surface temperatures reduce the temperature gradient between the core temperature and the surface of the skin and may therefore compromise thermoregulation.
In a more recent study however, Connolly & Wilcox, (2000) demonstrated that the use of sunscreen resulted in a cooler skin temperature, thus increasing the potential for heat loss. Although offering a robust defence of their methodology, which they believe to be superior to the earlier study, they were unable to offer a definitive explanation as to their findings. Interestingly they did note that the amphipathic nature of sun screens (contains molecules with water-loving and fat-loving properties) may result in more water being trapped on the skin and available for evaporative cooling, rather than just dripping off the skin without contributing to cooling.
A similar Australian study was conducted to clarify whether wearing sunscreen could compromise the ability to maintain core temperature in safe limits during exercise. Naughton et al. (2000) concluded that there were no detrimental effects to exercise performance or thermoregulation through sun screen usage.
If sunscreen has no detrimental effect on sweating and thermoregulation the same cannot be said for sunburn. Reporting a study in the Journal of Physiology, Thompson (1951) described his observations working as a Medical Officer in Ceylon during the ‘last war’. He noted that personnel exposed to sufficient sun to cause reddening had a reduced sweating rate and described a series of studies replicating this effect in a clinical setting. In a later paper (Thompson,1951a), he explored the possible mechanisms by which the trauma of sunburn could result in impaired sweat gland activity.
In conclusion, whilst there is limited published research on the effects on sunscreen on sports performance, there is little doubt that sunburn should be avoided. Some sun exposure is beneficial for natural vitamin D production, but this is best done with controlled exposure – there is little support for forgoing sun screens for sports performance.
A winning ‘tan’ probably has more to do with increasing carotenoid pigments than melanin; - Your Grandmother was right, and so was Baz Luhttps://www.youtube.com/watch?v=sTJ7AzBIJohrmann;- eat your vegetables and take your fish oils: wear sunscreen!