Introduction

Despite the initial unlikely acquaintanceship between physical exercise and skin cancer, understanding their relationship is crucial for maintaining good skin health and physical fitness in general. This article will examine the relationship between the two and provide recommendations on how to balance our need for physical activity to maintain good health with the need to protect ourselves from sun exposure when exercising outdoors.

Importance of physical activity for overall health

Regular physical exercise is beneficial for your overall health because it can:

• Help prevent a range of diseases, including heart disease, diabetes, and hypertension 
• Boost your immune system, thereby keeping you healthy by preventing infections¹

Physical activity is good for health, but being physically active outdoors means our skin is exposed to UV radiation. This is the leading cause of skin cancer. Understanding how to exercise outdoors while remaining protected from the sun is critical for promoting skin health and general well-being.

Ultraviolet exposure and skin cancer

Prolonged exposure to ultraviolet radiation (UVR) is well-recognised as a significant risk factor for both melanoma and non-melanoma skin cancers, along with genetic predisposition and a weakened immune system.

Sweating during physical activity can contribute to UV-related skin damage by enhancing skin photosensitivity and increasing the risk of sunburn.

Understanding skin cancer

Skin cancer is defined as the uncontrolled multiplication of abnormal skin cells. It is one of the most prevalent types of cancer, with an estimated 1.5 million new cases diagnosed in 2022.

The three main types of skin cancer are basal cell carcinoma, squamous cell carcinoma, and melanoma, with each having different degrees of severity and spread. Basal cell and squamous cell carcinomas are the most frequently diagnosed types of skin cancer.

• Basal cell carcinoma appears as a little pink or red raised lump on the skin or a flat, scaly spot 
• Squamous cancer cells typically form on body areas that are regularly exposed to sunlight, such as the face, neck, ears, lips, and throat
  • They resemble a scaly, reddish, or pink patch, lump, or sore that will not heal
• Melanoma is a less commonly diagnosed form of skin cancer
  • It begins with your melanocytes, which create melanin – the pigment that gives skin, hair, and eyes their colour 
  • Melanoma typically appears as an irregularly shaped mole or pigmented patch on the skin
  • It is more aggressive and more likely to spread to other parts of the body 

The role of UV radiation

Ultraviolet radiation damages DNA in our skin cells which can lead lead to mutations in our DNA sequence. This mutation is what causes cancer.

UV radiation types

UV radiation is classified into the following three main types, based on their wavelengths:

• UVA: penetrates deeply into the skin, causing accelerated aging and long-term damage
• UVB: causes sunburn and has been related to the development of skin cancer
• UVC: is mostly absorbed by the Earth's atmosphere and does not reach the ground hence there is no major danger of skin cancer

The impact of sun exposure on skin cancer risk 

• Prolonged or strong sun exposure, especially during childhood, dramatically raises the chance of developing skin cancer later in life
• The risk is increased for people who engage in outdoor activities without proper sun protection

How physical activity influences skin cancer

Reducing overall cancer risk 

• Research shows that regular physical exercise, alongside a balanced diet, can help lower the risk of several malignancies. There is some evidence to suggest that increased levels of physical activity are associated with a decreased risk of skin cancer²
• Exercise also improves general health by reducing the risk of heart disease, stroke, and diabetes

Preventing recurrence 

• Maintaining an active lifestyle after treatment for skin cancer can help prevent cancer recurrence 

Prehabilitation 

• If you are going to begin cancer treatment, you should consider a process of prehabilitation (also known as preoperative rehabilitation or "prehab") which can involve exercises and other interventions
  • Prehab entails being physically ready for treatment by improving fitness and psychologically preparing for what comes next. It aims to reduce side effects and complications from treatment and enhance recovery

Physical activity and increased sunlight exposure

Common outdoor physical activities include: 

• Jogging 
• Cycling 
• Hiking 
• Swimming
• Team sports 

Each of these activities can require lengthy periods of sun exposure, especially during the peak hours for UV radiation (between 11 a.m. and 4 p.m). People who participate in outdoor sports or exercise can experience a lot of UV exposure, especially if they spend time outside around noon when UV radiation is at its peak.³

According to studies, outdoor athletes are more likely to develop skin cancer. Endurance runners, for example, have an increased risk of developing skin lesions and cancer as a result of prolonged sun exposure.^3,4,5

Protective measures 

Sunscreen 

• Use a broad-spectrum sunscreen (i.e. one that protects your skin from both UVA and UVB rays) with an SPF (sun protection factor) of at least 30 
• Higher SPF ratings offer more protection from UVB rays, particularly during prolonged outdoor activity
• Apply sunscreen liberally 15-30 minutes before heading outside 
• Reapply every two hours, or more regularly if you’re exercising or swimming

Protective clothing

• Hats: Wear wide-brimmed hats to protect your face, ears and neck
• Long sleeves and UV-blocking fabrics: Choose long-sleeved shirts, long pants, and UV-protective clothing

Time 

• To avoid peak UV exposure, plan outside activities for the early morning or late afternoon, when UV radiation is lower
• Avoid outdoor activity between 10 a.m. to 4 p.m 

Seeking shade and umbrellas 

• When feasible, remain in shady places or use umbrellas to reduce direct sun exposure
• There are some umbrellas available on the market designed to block UV radiation

Balancing physical activity and sun safety

• Need for regular physical activity: We all need to maintain physical fitness for general health, both mental and physical
• Indoor workout options: Indoor activities such as gym workouts, indoor swimming, yoga, and fitness courses are recommended as alternatives to outside activities
• Combining indoor and outdoor activities for a healthy lifestyle: Aim for a combination of indoor and outdoor workouts to reap the advantages of both types of exercise while minimising UV exposure. For example, rotate between indoor workouts and outdoor activities during the peak sun hours

The advantages of physical activity for skin health

• Improved circulation: Regular exercise increases blood flow to the skin, supplying more oxygen and nutrients. This effectively enhances skin health and appearance⁷
• Stress reduction: Physical exercise lowers stress levels, which can help manage stress-related skin disorders such as acne and eczema⁶
• Potential role of exercise in skin cancer prevention: According to research, regular physical activity can enhance the immune system.¹ This increases the body's ability to repair DNA damage, potentially lowering the risk of skin cancer⁴

FAQs

What is the best type of sunscreen to use for outdoor activities?

Use a broad-spectrum sunscreen that has an SPF of 30 or higher. Look for water-resistant formulas if you'll be sweating or swimming.

Can I still get enough exercise if I avoid the sun?

• Yes, you can engage in indoor activities such as gym workouts, swimming in indoor pools, and exercise classes 
• Additionally, outdoor activities can be scheduled during the early morning or late afternoon when UV radiation is less intense

How often should I reapply sunscreen during exercise?

Reapply sunscreen every two hours, or more frequently if you’re swimming or sweating heavily.

What are some signs of skin cancer I should look out for?

• Look for new or changing moles, sores/ulcers that don't heal within four weeks or any unusual growths or lumps on your skin 
• If you notice anything suspicious, consult your doctor promptly

Summary 

• Physical exercise and skin cancer are closely related, with the most direct link being the risk posed by prolonged sun exposure
• Outdoor physical activity is good for overall health, but it means our skin is exposed to UV radiation, which is the main cause of skin cancer
  • The three main forms of skin cancer are basal cell carcinoma, squamous cell carcinoma, and melanoma
  • Ultraviolet radiation damages the DNA in our skin cells, leading to mutations that cause cancer
• Engaging in outdoor activities in which you are exposed to the sun for extended periods, increases the risk of sunburn and skin cancer. However, with the effective use of preventive measures, it’s possible to enjoy regular workouts outside, while reducing your risk of developing skin cancer
  • Key preventative measures include: applying a broad-spectrum sunscreen, wearing protective clothing, and refraining from exercising during the hours of peak UV exposure (10 a.m to 4 p.m.) 
• Understanding how to combine sun protection and physical exercise is critical for preserving skin health and general well-being 
• Regular physical activity can also influence skin cancer by reducing overall cancer risk, being a valuable step in pre-treatment ‘prehabilitation’ and preventing recurrence