Extreme athletes’ nails experience enormous pressure and tension as a result of their activities. Abrupt and intense forces can completely remove a finger or toenail. More commonly, athletes develop nail changes related to chronic, low-grade pressure, and tugging. The changes related to these physical forces include longitudinal and transverse ridging, onycholysis (separation of the nail plate from the nail bed), discoloration around the periungual area, and calluses periungually (Fig. 6.2) [1, 3].

Extreme athletes must employ several techniques to prevent athlete’s nail. All nails should be closely cut in a straight-across fashion that allows an equal distribution of the force created during the athlete’s physical activity. Cutting nails in a curved manner places increase pressure on the middle portion of the nail. As the sport allows, wearing gloves also helps to reduce the friction and pressure experienced by fingernails. Extreme athletes need to ensure that their footwear has an adequate toe box [1]. Unique lacing techniques can also redistribute the physical forces away from the toenails and onto the ankle which is better suited to experience the forces that create long-term nail changes. To employ this lacing method, the athlete undoes both laces from the last eyelet; instead of crossing the lace into the opposite side’s eyelet, one enters the eyelet on the same side such that two loops are generated. The free lace ends then are crossed and thread through the opposite loop. Then the athlete can tie the ends as usual [4].

The significance of talon noire resides in the fact that this condition can confuse the clinician to believe that the athlete has warts or melanoma. Talon noire, otherwise known as black heel, occurs most commonly in younger athletes on the posterior lateral or medial heel (Fig. 6.3) [1]. Caused by friction with subsequent hemorrhage into the skin, talon noire is asymptomatic and requires no therapy [5].

In addition to friction, pressure can also create havoc in an extreme athlete’s skin. Piezogenic pedal papules primarily affect the feet of young women, and while most often not painful, the discomfort associated with the condition can prevent the endeavors on the extreme athlete. The subcutaneous fat and associated nerves and microvasculature protrude up into the dermis that can cause strangulation and subsequent pain [1]. Clinicians may misdiagnose the foot pain and embark on an extensive musculoskeletal work-up without having the athlete stand on only the affected extremity that then readily reveals the skin colored to yellow papules most often on the sides of the heel. Multiple therapies exist including intralesional steroids [6], compression [7], and acupuncture [8]. Susceptible athletes sometimes find heel pads prevent piezogenic pedal papules.

A combination of pressure and friction, particularly along the lower extremities, can cause a skin condition called athlete’ nodules. Two mechanisms exist by which athletes can develop these lesions. First, surfers get “surfer’s knots or nodules” on their legs as a result of pressure, friction, and rough board surface (along with sand) [9]. As surfers paddle out to catch waves (especially those in colder waters), they kneel on the board, and the combination of these factors and forces creates a foreign-body reaction in the skin. Second, these nodules can develop as a reaction to constant pressure in one particular location that most often related to protective equipment or shoewear. As a result, the dermis hypertrophies creating a collagenoma.

Regardless of the exact etiology, the differential diagnosis of these firms, skin colored to erythematous nodules can be vast. Atypical mycobacterial and deep fungal skin infections have this appearance, as do inflammatory conditions such as granuloma annulare and rheumatoid nodules. Primary and secondary malignancies can also share a similar morphology. While a biopsy will differentiate among these various cutaneous ailments, linking the lesion to one’s athletic pursuits facilitates early accurate diagnosis.

Athlete’s nodules may require excision, while others respond to intralesional steroids. Occasionally changing the equipment or footwear results in clearance. To prevent athlete’s nodules, extreme athletes can wear padding between their skin and the offending piece of equipment [10]. In the case of surfer’s knots, surfers may lie prone on the board to equally distribute forces along the board. Surfers, in colder waters, may wear a wet suit to comfortably allow a prone position.

Extreme athletes experience an enormously high level of ultraviolet radiation (UVR). As a result, these athletes ultimately risk acquiring skin cancer and actinic damage (wrinkles and dyspigmentation) (Figs. 6.4 and 6.5).

Several factors result in this intense UVR exposure. Athletes practice and compete during the time of peak UVR that is between 10 am and 4 pm. Additionally, they train for long periods of time and started this training often early in their life resulting in an immense total lifetime exposure. Sweating, inherent to most extreme sports, enhances the potency of the UVR such that it takes 40 % less UVR to burn athletes if they did not sweat [11]. Several extreme sports exist at very high altitudes. At high altitudes, the atmosphere has not had a chance to filter a significant portion of UVR. For example, the UVR experienced high in the mountains is comparable to the UVR affecting an individual at sea level [12]. Lastly, extreme athletes who compete in snow and water environments must also contend with the significant reflection of UVR off the surfaces. Wearing hats that shade the face will provide no protection against UVR reflecting up to the athletes’ face from the environment.

To prevent sunburns and long-term actinic damage, athletes must apply water- and sweat-resistant sunscreen and reapply the lotion or spray after practicing or competing. They should take care to apply areas that athletes often forget which include the ears and any part created by hairstyles. If possible, athletes should avoid the peak hours of UVR exposure and practice early morning or evening. Tightly woven and dark clothing provides ideal sunblocking properties. While athletes traditionally prefer light-colored clothing to keep them relatively cool, the myriad commercially available synthetic moisture-wicking clothing allows the athlete to wear a sporting garment with both excellent UVR-blocking capabilities and good cooling qualities [1].

Exposure to extraordinary heat and UVR plays a major role in many extreme sports. One relatively rare cutaneous condition that may occur more often in this population is miliaria crystallina. An affected athlete will develop delicate, crystal-like, small vesicles on their skin; unsuspecting clinicians may misdiagnose the lesions as herpes or another skin infection (Fig. 6.6).

Miliaria crystallina, which results from superficial obstruction of the eccrine duct, highlights the fierce heat that challenges the athlete. Wearing moisture-wicking, dark-colored synthetic clothing will assuage some of the affect of the heat [1].

While heat can cause many ailments in an athlete’s skin, cold exposure poses its own challenges. Prolonged exposure to cold can cause significant damage to the cutaneous structures. Wind and moisture can exacerbate the issue. An extreme athlete with frostbite will initially complain of pain and develop erythema on the toes and fingers; as the condition progresses, necrosis ensues. To treat frostbite, clinicians should rapidly rewarm the area by dunking in 40 °C water [13]. This treatment should only occur if no chance of subsequent exposure to prolonged cold remains. Rewarming frostbitten skin and subsequently refreezing that skin result in maximal tissue damage. Extreme athletes whose environment includes freezing temperatures must use thermal clothing and gloves and chemical heating packets [1, 13].

While uncommon overall, extreme athletes risk encounters with water creatures that can affect their skin. Water-based extreme athletes may experience painful jellyfish stings from their long tentacles. Once the tentacles contact the skin, nematocysts fire and cause a linear, erythematous, and edematous eruption. Treatment includes removing the tentacles with tweezers and applying vinegar solution. Athletes and clinicians should avoid applying freshwater that can activate the nematocysts [1]. Extreme athletes who wish to enter seawater with jellyfish should minimize skin exposure by wearing wet suits as their sport allows.

Among the most common cutaneous ailments in extreme athletes, after traumatic skin events result from allergies. The main categories of allergy include allergic contact dermatitis, exercise-induced anaphylaxis, and urticaria.