by Jo Vartanian

If you’re like me and many other Australians, we love our long hot summer days and getting outdoors on our incredible hiking trails. But with our Australian climate comes the added risk of heat-related illness.

Some of Australia’s best multi-day hikes like the Larapinta Trail, Overland Track and Six Foot Track require careful management of hot conditions, even in winter months.

Even hiking in the Blue Mountains or any of our National Parks is not without risk. The same management strategies we use for long day hiking should be used when training or exercising outdoors.

Over 10 years of hiking and trail running with teams of women in Australia and around the world has exposed me to incidences of heat-related illness (in myself and in others). I’ve learnt what works to prevent and manage these serious conditions. My training, experience and the Sports Medicine Australia’s (SMA) evidence-based guidelines, in their 2021 Extreme Heat Policy, inform the following.

Midday rest after an early start on the Jatbula Trail, NT.

When is it too hot to hike or Trek Train in Australia?

The common occurrence of high temperatures and high humidity in Australia is an important consideration because the risk of heat-related illness occurs at lower temperatures. This is due to the reduction in the efficiency of the body’s natural ability to cool itself. When the air is damp, sweat evaporation which usually cools the body is decreased.

SMA has come up with a temperature/humidity graph that allows you to assess heat stress risk. For example, for hiking at a brisk pace, a temperature of 35 degrees and 60% relative humidity (RH) would put you in the extreme risk category. At 90% RH you would be in the extreme category when the temperature is just 29 degrees. At the extreme risk level, you should stop exercising and rest in the shade.

Graph courtesy of Sports Medicine Australia.

Can you still hike when it is hot?

YES! If the temperature and RH put you below the ‘extreme’ risk category, then there are things you can do to manage your risk very effectively. It involves planning ahead - often overlooked by inexperienced hikers.

HYDRATION

This begins well before you step outdoors. Every 2-3hrs before your hike or training you should consume around 500ml of water. Eating a good balanced meal and/or using electrolyte supplementation is also important. Beginning your hiking day well hydrated is my NUMBER ONE tip for managing heat. I start the hydration process several days before an event or trek and if I’m on a multi-day trek, hydrating the evening before, during the night and in the morning is top of my ‘to-do list’. Fear of peeing in the bush and/or waking at night and having to leave your tent and warm sleeping bag must not be a reason to avoid these hydrating essentials.

You need to offset the fluids your body uses by replacing them during exercise. Everyone is different. We recommend 3L for a full day hike. To determine how much fluid you use during a session, record how much fluid you consume and weigh yourself before and after the session. Calculate the difference to determine your fluid needs. Drinking too much fluid can also have negative impacts on your health.

CLOTHING

Layering allows you to adjust to your body temperature requirements. Wearing lightweight, loose, breathable clothing is important to allow the body to use it’s natural evaporative cooling system. When sweat meets the air, the body cools, so the skin needs to be exposed. Don’t cover yourself with such things as long tights or skins. Use sunscreen on exposed skin (sunscreen will not impede sweating). Avoid cotton fabrics and choose synthetic or merino fabrics with wicking/cooling properties.

REST BREAKS and INTENSITY

Increase the frequency and duration of rest breaks during periods of high risk. Decrease the intensity of your hike or training by moving at a slower pace, avoiding steep terrain, hiking in cooler areas and times of day, and avoiding high-intensity interval training.

ACTIVE COOLING

You can take active measures to assist the body’s cooling system. These include wetting down the skin with available water (wet your cap, wipe your skin with a wet buff, pour water over your arms and head, use a spray bottle for your face and body and best of all, jump in a waterhole). Gel or ice packs and wetted neck scarves are excellent cooling products. Increasing airflow on the skin through fanning or hiking in open areas where there is a breeze will improve evaporative cooling.

Waterholes like this are made for plunging!

Is there anything you can to do to prepare for hiking in hot conditions?

Definitely. Just like acclimatising for hiking in high altitude conditions, you can acclimatise your body to manage heat better. It takes around 2 weeks to acclimatise to hot conditions. Gradually increase the temperature you train in and begin with walks of around 1-2hrs. Learning to manage the heat is an important part of this preparation phase and it’s much better to do it in a controlled training session than once you are out in a remote hiking location where the risks are significantly greater.

Even more important is building your fitness over a long period of time so that your body is more efficient on the trails and its cooling response is more effective. Increasing your aerobic capacity will allow you to tolerate heat better. Strength training (that’s why hill training and those pack-weighted squats and lunges are included in our training) results in less exertion on steep, hilly trails and consequently, your body temperature remains more stable.

Our Summer Trek Training adopts active cooling methods.

How do you know if you are experiencing a heat-related illness and what do I do?

If you notice any of the following symptoms, chances are your body is experiencing some degree of heat illness and you need to act quickly. If left untreated heat illness can become heat exhaustion then heat stroke, which is potentially fatal. The early symptoms include:

· Muscle cramps

· Nausea or vomiting

· Dizziness/fainting

· Headache

· Increased heart rate

· Increased sweating

· Dry mouth/excessive thirst

· Vision problems

If you or someone you are with is experiencing any of these symptoms stop immediately and take steps to cool the person and ensure they are hydrating. Move them to a cooler, shady area, lie them down and elevate the legs, and remove or loosen clothing. Give water and /or electrolyte drink and place ice packs or cool wet cloths under their arms and on the back of the neck. Fan the person and if they do not show improvement in 30 minutes seek medical help.

A cooling moment on the Larapinta Trail.

Are you in a high-risk group for heat-related illness?

Even the fittest athletes can experience heat-related illness but there are certain groups who are especially vulnerable.

· Thermoregulation may become progressively worse as we age, so be more mindful if you are aged over 65 years (especially if you are unfit).

· Recently sick with a fever

· Heart or Kidney disease/condition

· Taking prescription medication that impedes sweating

· Very high body fat

· Recently (in the past week) returned from a cold climate

A Final Word

If you live in Australia and love hiking, then the chances are you will be hiking in hot, humid conditions at some point. It doesn’t have to stop you. With some good planning and making sure you maintain a good level of fitness, managing the heat will be just another skill in your hiking tool kit.