Exercising in Extreme Heat: A Safe and Practical Guide for Hot Climates

Why does heat make exercise harder?

When you exercise your body produces heat as a byproduct of muscle work. In a mild climate, the body disperses this heat efficiently through sweating and increased blood flow to the skin. In very hot weather, that heat transfer becomes much harder: the temperature difference between your body and the air is smaller, and your heart must pump hard to serve both working muscles and the skin simultaneously.

A major review published in Physiological Reviews in 2021, titled 'Exercise under heat stress' by Periard, Eijsvogels, Daanen and colleagues, shows that heat stress substantially reduces exercise capacity even in fit individuals, and that the cardiovascular system under combined exercise and heat load is genuinely more strained than either alone. This is not a matter of willpower: it is physiology.

High humidity compounds the problem. Sweat evaporating from the skin is what actually cools the body. In humid air, evaporation is slower, so the cooling effect of sweating is diminished even as you sweat more. This is why humid heat in coastal parts of the Gulf, Yemen and the Levant can feel more dangerous than dry heat at the same temperature.

When is the right time to exercise in summer?

Timing is the single most important decision for outdoor exercise in the Arab region during summer. Peak temperatures in most of the Gulf, Iraq and Egypt fall between noon and 6 pm. Avoiding this window entirely for outdoor physical activity is not excessive caution: it is basic safety.

The two best windows are before 7 am, when the ground is still releasing overnight cool and air temperatures are typically between 28 and 35 degrees, and roughly one hour after sunset, when solar radiation has ended and the air begins to cool. Early morning is usually better for longer efforts; evenings suit those who do not rise early.

Consensus recommendations published in British Journal of Sports Medicine in 2015 by Racinais and colleagues advise reducing exercise intensity and duration at peak heat, favouring early morning or late evening sessions, and postponing hard efforts until heat acclimatisation is complete. These were written for competitive athletes: for the general public starting out, the caution is even more applicable.

Heat acclimatisation: two weeks that change everything

Heat acclimatisation is the body's process of adapting to hot conditions through repeated graded exposure while exercising. Over 10 to 14 days of daily activity in the heat, measurable physiological changes occur: blood plasma volume expands, sweating begins earlier and at a higher rate, the sweat becomes more dilute conserving salt, and cardiovascular strain at a given effort level decreases. The body becomes genuinely better at cooling itself.

A 2021 roundtable published in Journal of Athletic Training by Adams, Hosokawa, Casa and colleagues on heat acclimatisation in sport found that full adaptation takes 10 to 14 days and that the first three to five days are the highest-risk period, because the body has not yet built its heat-coping capacity. This window requires the greatest caution in terms of intensity, duration and external conditions.

The practical implication: if you exercised indoors all winter and now want to resume outdoor activity in summer, your body is not acclimatised. Start with 20 to 25 minutes of light walking in the early morning during the first week. Add time and pace gradually over two weeks before any sustained effort in the heat.

Hydration: how much and when

Thirst is a delayed indicator of dehydration. By the time you feel thirsty, your blood volume has already dropped enough to reduce both physical performance and cognitive function. Building a pre-emptive hydration habit matters far more than trying to catch up once thirsty.

General guidance for moderate exercise in heat is to drink 200 to 250 millilitres (a large glass) every 15 to 20 minutes during activity, adjusted for body size, exercise intensity and humidity. A simple and reliable check is urine colour: pale yellow indicates good hydration; dark yellow or amber means you need more water. Aim to go into a session already pale yellow.

Sports drinks containing carbohydrates and electrolytes are useful for exercise lasting more than one hour in serious heat, because sweat losses include sodium and potassium alongside water. For light to moderate exercise under an hour, plain water works perfectly well and costs nothing. Caffeinated drinks and carbonated beverages are poor substitutes during exercise because caffeine has a mild diuretic effect and carbonation limits the volume most people can drink.

Indoor options: mall walking is real exercise

In parts of the Gulf, summer air temperatures reach 45 to 48 degrees with high humidity, making outdoor daytime exercise genuinely dangerous for almost everyone regardless of fitness level. Treating indoor alternatives as less valid than outdoor exercise misses the point: the health benefits of regular movement are the same regardless of setting.

Walking in shopping malls, particularly early in the morning before crowds build, is practiced widely across the Gulf and is actively recommended by cardiologists for patients who need regular walking but cannot tolerate environmental heat. The flat even surfaces, consistent temperature and accessibility make malls a practical venue for the general public and for older adults or those with chronic conditions.

A 2025 review published in BMJ Global Health by Alzahrani and colleagues on physical activity policy across GCC countries noted that indoor infrastructure including malls and covered sports facilities represents a primary resource for physical activity in hot climates and should be promoted as a genuine health asset. The WHO physical activity guidelines published in 2020 make no distinction between indoor and outdoor exercise: 150 to 300 minutes of moderate activity per week carries the same benefits regardless of where it happens.

Starting from scratch in a hot climate

A 2018 systematic review in International Journal of Health Sciences by Al-Hazzaa found that over 50 percent of adults in Saudi Arabia were insufficiently active, with heat consistently cited as a primary barrier. This figure is likely representative of much of the Gulf region. It shows that the challenge is real and shared, and that starting from inactivity in a hot environment needs a specific approach, not generic gym advice.

The WHO 2020 physical activity guidelines set a target of 150 to 300 minutes per week of moderate-intensity activity. That is achievable in small daily pieces: three 20-minute walks on weekdays, two longer sessions at the weekend, or a mix of indoor and outdoor activity across the week depending on temperature. No single session needs to be long or hard to contribute to the total.

A realistic first-month plan for someone starting from inactivity in a hot climate: week one, walk 20 minutes three times per week in the early morning. Week two, increase to 25 minutes four times per week, or use an air-conditioned mall. Weeks three and four, add a fifth day or increase pace. Month two, introduce light resistance exercises at home on non-walking days. The goal is consistency over months, not transformation in weeks.

Exercising during Ramadan

Exercising while fasting during Ramadan requires a different plan because daytime heat and no fluid intake cannot safely combine. The two practical options are exercising after iftar, ideally one to two hours after eating, or exercising in the final hour or two before iftar with very light intensity only.

Post-iftar exercise takes advantage of cooler evening temperatures, available hydration and some fuel from the meal. Wait at least an hour after eating before starting any sustained effort. Resistance training and stretching suit this timing well. If you prefer cardiovascular exercise, choose moderate intensity rather than pushing hard in the first Ramadan weeks.

The goal during Ramadan is to maintain your activity level and preserve muscle, not to achieve new fitness gains. Overexertion combined with fasting increases injury risk and may slow recovery. Many people find that 30 minutes of moderate activity four or five evenings per week is both achievable and sufficient to maintain conditioning through the month.

Clothing and gear for hot conditions

Clothing choice genuinely affects how your body manages heat during exercise. Moisture-wicking technical fabrics pull sweat away from the skin surface and allow faster evaporation, which improves cooling. Heavy cotton absorbs sweat and stays wet against the skin, reducing evaporative cooling and adding weight. Light-coloured garments reflect more solar radiation than dark ones, a meaningful difference during outdoor morning exercise.

A wide-brimmed hat or cap shading the face and neck reduces direct radiation loading significantly. Sunscreen on exposed skin protects against UV damage and prevents the skin surface changes that can impair sweating over time. In very humid conditions, some people find lightweight ventilated gloves useful if they need to grip equipment with sweating hands.

Footwear matters in a specific way in the region: paved and asphalt surfaces in summer reach temperatures of 60 to 70 degrees. Well-insulated shoes with good soles protect the feet from this conducted heat and from the impact-related injury risk that increases when muscles fatigue faster in heat. Replace worn-out athletic shoes rather than continuing with depleted cushioning.

In the Arab and Muslim context where many people, particularly women, exercise in modest or loose-fitting clothing, fabric choice becomes even more important. Loose garments can work well if they are made from breathable, lightweight technical fabric rather than heavy cotton. The goal is to keep fabric from trapping heat against the body. Many sports brands now produce full-coverage activewear designed for this purpose. The specific style is much less important than the fabric weight and breathability.

Monitoring how your body is coping

Paying attention to how you feel during and after exercise in heat is one of the most important habits you can build. Early warning signs that your body is under heat stress include a heart rate that feels unusually high for the effort level, a strong desire to stop that comes on faster than usual, and headache or nausea that starts during exercise. These are signals to slow down immediately, find shade and drink water.

A simple tool used by athletes training in the heat is to track resting heart rate each morning before getting out of bed. An elevated morning heart rate of more than five to eight beats above your normal baseline often signals incomplete recovery, whether from heat stress, dehydration or inadequate sleep. On those days, reduce exercise intensity or switch to a gentle indoor session rather than pushing through.

Over two to three weeks of gradual heat exposure with moderate exercise, you should notice that a given effort level feels easier, your heart rate at that effort is lower, and you begin sweating sooner into exercise (an indicator of improved heat adaptation rather than a problem). If after three weeks of regular activity you still find heat exercise as difficult as day one, that is worth mentioning to a doctor as it may point to a cardiovascular or metabolic issue worth checking.

Sources

• Periard JD, Eijsvogels TMH, Daanen HAM et al: Exercise under heat stress: thermoregulation, hydration, performance implications, and mitigation strategies, Physiological reviews, 2021
• Racinais S, Alonso JM, Coutts AJ et al: Consensus recommendations on training and competing in the heat, British journal of sports medicine, 2015
• Bull FC, Al-Ansari SS, Biddle S et al: World Health Organization 2020 guidelines on physical activity and sedentary behaviour, British journal of sports medicine, 2020
• Al-Hazzaa HM: Physical inactivity in Saudi Arabia revisited: A systematic review of inactivity prevalence and perceived barriers to active living, International journal of health sciences, 2018
• Alzahrani AA, Gelius P, Grunseit A et al: Physical activity policies in the six Gulf Cooperation Council countries: a qualitative study with document analysis, BMJ global health, 2025
• Adams WM, Hosokawa Y, Casa DJ et al: Roundtable on Preseason Heat Safety in Secondary School Athletics: Heat Acclimatization, Journal of athletic training, 2021