Heatstroke and Injury Prevention
What is Heatstroke?
Heatstroke, or exertional heat illness, is a group of conditions that result from doing strenuous exercise or excessive activity in the presence of heat, humidity, or other factors that make it difficult for the body to maintain a constant balanced temperature. Heatstroke can be a medical emergency, but often the lesser transient type of heat illnesses are the ones we are all familiar with (Giersch, Belval & Lopez, 2020).
What Causes Heatstroke?
Our bodies are very good at achieving and maintaining a state of balance in all of the systems required for survival, a state of being called ‘homeostasis’. Imbalance occurs when we can’t regulate our body temperature due to exposure to excessive external heat, or from a lack of ability to cool down, e.g. dehydrated from excessive sweating.
Medically speaking, heatstroke is occurring when the core body temperature is higher than 40℃. However, the patient doesn’t need to have a temperature at or above 40℃ for the situation to be life-threatening. So while a high temperature is dangerous, a lack of a high temperature shouldn’t be a sign that nothing serious is going on (Giersch, Belval & Lopez, 2020).
Dehydration is a condition where there is a lack of fluids in the body, or a lack of specific dissolved salts or electrolytes in that fluid, which leads to poor functioning of the body and mind. Dehydration can occur in a variety of ways, including illness, forgetting to drink enough water, and excessive sweating. Our bodies cool by sweating, but if we’re dehydrated, we can run out of the water to sweat out, and our core body temperature rises (Vic State Govt, 2015).
Heatstroke and dehydration can occur together, although this is not always the case. Both are common in our active and sporty Australian society; both in our organised sports for both children and adults, our recreational sports like surfing and hiking, and outdoors lifestyle, like beach days and backyard cricket.
Lack of Airflow, Crowded Conditions
If you’ve ever been to a summer music festival, hiking in waterproof clothing, inside a busy nightclub or stuck inside a full elevator you’ve experienced this one. Escaping the radiating body heat from yourself or others when you’re insulated can be tricky, even impossible. When you’re close together for long periods, your body can’t escape this radiating heat, and your internal temperature stays high (Giersch, Belval & Lopez, 2020).
Everyone loves a nap after a morning spent at the beach, but this exhaustion is a form of heat illness often accompanied by dehydration. Not to mention the thirst, fatigue and pain if you wake up from that nap with a sunburn.
Australia routinely runs sun exposure and sunburn awareness campaigns, and workplaces often supply mitigation – hats, sunscreen, water, and shade resting areas. For about a quarter of the Australian workforce, who work in the sun, particularly people who work in the middle of the day are at increased risk for sun and heat exposure (SafeWork Australia, 2020).
Even if you’ve never had the bad luck to experience a full-blown bushfire, you’ve probably stood a little too close to the campfire. A slightly lesser version, but you might have had an oven, stove and slow cooker going in a sunny kitchen – the heat feels inescapable. Radiant heat can quickly cause dehydration, heat illness and exhaustion. Bushfires typically occur when the air is scorching and dry, which can compound the dehydration and heat illness risk factors (Vic State Govt, 2015).
Usually, heatstroke and dehydration can be diagnosed clinically, with a check for these signs and symptoms. Scans or blood tests typically aren’t needed.
The simplest way to tell if you’re experiencing dehydration is to have a look at the colour of your urine. You might have seen charts like this pop up on the back of toilet doors in the last few years, especially in public toilets.
How to Tell if Heat Illness is a Medical Emergency
(SA Health, 2018)
Why is this Important for Physiotherapy and Sports Performance?
As physiotherapists, it is our job to keep our athletes safe when we are looking after them from the sidelines. Player wellbeing includes having an understanding of the complex interactions between ‘medical’ health factors, and ‘physical’ health factors, as well as emotional, psychological and societal factors. Heat illness is becoming increasingly important to understand as average temperatures continue to rise (Kakamu et al., 2017).
There is a lack of research around whether extremes of temperature lead directly to injury during sport. The lack of research is probably likely because it is unethical to subject people to hard work at various temperatures to see who gets most injured. After all, we already have researched how detrimental it can be to our brains and bodies. There is evidence mostly in occupational, military and industrial settings, as well as lab research that guides us in decision making for keeping our patients (both athletes and workers) safe in sweltering conditions. Several factors loosely point towards increased heat exposure leading to an increase in injuries.
A study completed by researchers in Iran (Mazloumi et el, 2014) found that working in heated conditions led to a slow down in reaction time, and a more inferior selective attention ability (the ability to focus on one thing without getting distracted).
The Journal of American College of Nutrition (Lieberman, 2007) published an article called ‘Hydration and Cognition: A Review’. The article discussed a variety of different studies, grouped by the way they induced dehydration. In the research they found was most robust in the ‘heat or exercise’ method of dehydration, showing a consistent downward trend of cognitive abilities with dehydration measured at 1%, 2%, 3% and 4% of body weight when subjects tested for hand-eye coordination, symbol substitution and a concentration test.
Again, don’t forget your day at the beach – that nap that you need..? Well, it’s shown that the cognitive deficits (like poor coordination, reduced information processing, decreased memory and attention span) may show up after 1-2 hours after exposure, from as little as a 1.8℃ increase in core body temperature (Walter et al., 2016). You need a nap because your brain is slowing down to recover!
In a large multi-country study, 30% of workers worldwide experienced a reduction in productivity while working in hot conditions (Flouris et al., 2018). Also, the same study found that proper medical assessment and risk prevention measures for mitigating heat stress in employees significantly reduced lost-injury time and returned workers to their jobs safely in mining, military, and firefighting industries, as well HAZMAT workers.
Muscle cramps are painful sustained muscle contractions or spasms. We know that these cramps are due to changes in the nervous system, but there is some weak evidence to suggest that heat and dehydration can contribute to an increased incidence of cramping (Miller, 2018).
Muscle Function and Strength
In a 2019 study (Racinais et al.) researchers took volunteers and asked them to perform sustained maximal muscle contractions. They found that when volunteers were heated up first, they subjectively reported their strength felt the same, but in fact, their muscle contraction wasn’t as durable over time. The peak torque and peak voluntary activation of fibres both dipped after only 20% of the length of the contraction. However, it found that heat acclimatisation can partially compensate for these effects. This finding is in line with other research suggesting that training in the heat can be beneficial for maximising competitive performance in hot weather.
Proprioception is also known as joint position sense and is used to balance and orient us in the world around us.
A joint Qatari-French study from 2018 (Mtibaa et al.) showed that inducing a state of hyperthermia (increased internal body temperature) produced worse results on several balance tests. This finding is suggesting decreased ankle proprioception. Participants asked to balance on one foot in a variety of tasks found that the participants balancing after they were passively heated up needed more contact with the ground to compensate for lack of joint sensation. Plus, quicker active electrical signalling to the muscles from the brain after the heat suppressed the regular stretch H-reflex from the spinal cord.
The same group of researchers took another look the next year (Mtibaa, 2019) to take a look at ankle proprioception in a treadmill test. Participants asked to run at their own pace, either with or without environmental heating, ran in the heat ran slower, and with more movement error at the ankle. But this was well compensated for further up the body. This change in movement was consistent with other previous studies showing this change with runners who were experiencing exercise-induced fatigue.
It’s a funny term, but intestinal permeability refers to the ease with which certain substances and bacteria pass through the intestinal wall into the bloodstream. Usually, these gaps between cells are tiny, so the cells themselves act as a gatekeeper and filter. They decide which good things can come into the bloodstream and travel to the rest of the body, and keep the bad stuff like intestinal bacteria, indigestible food and bile in the intestine to be passed out as waste.
Hyperthermia leads to a state of high intestinal permeability; that is, the gaps between cells get more prominent, allowing some substances to ‘slip through the net’ and pass into the bloodstream. If these things are nasty, the immune system creates a systemic inflammatory response to target and neutralise the potential danger. Systemic inflammation, especially when prolonged, has been known to contribute to disease risk and reduce sporting performance (Pires et al., 2017).
What are the Heatstroke Treatment Options?
Treatment for heat illness and dehydration is relatively simple – cooling and rehydration. It’s essential to treat slowly to allow the body time to readjust, or it’s possible to make things worse. If you’re not sure, a call to 1800 022 222 or 000 is appropriate for guidance.
Your pitch-side physiotherapist is trained in advanced first-aid, including heat-related illnesses, in addition to their injury treatment training and experience. In the case of suspected acute heat-related illness, you can ask the physiotherapist or other health professional present at the game to assess you and guide you on the next steps for treatment and advice, if appropriate. If you’re looking to improve your balance, muscle function, the efficiency of movement and strength to counteract the effects of heat while playing your sport, you can book in to see one of our physios who will thoroughly assess you and recommend a treatment plan.
If you have any further question, please ask your physiotherapist.
References available on request.
Muscle Pain Injuries
Myalgia, or muscle pain, can have many sources. Here are some of the more common sources of your muscle pain. Please click the links for more information.
Muscle Strains By Region
Neck & Back:
Systemic Causes of Myalgia
More Information: Myalgia
Article by John Miller
Muscle Strain Treatment
Muscle strain treatment will vary depending upon an accurate diagnosis from your health professional. The severity of your muscle strain, and what function or loads your injured muscle will need to cope with, will impact the length of your healing and rehabilitation process.
Until you’ve been accurately diagnosed with a muscle strain, use the following guidelines:
- Ice and a compression bandage.
- Elevate the injured region if it is swollen.
- If it’s painful to walk you should be using crutches.
- Cease or reduce your exercise or activity level to where you feel no pain.
Muscle strain can take anywhere from a few days to several weeks to rehabilitate successfully. Please seek the advice of your physiotherapist, doctor or your health care practitioner who specialises in muscle injuries eg massage therapist, to guide your treatment.
Common Treatments for Muscle Strain
The following options are available to your physiotherapist to assist the rehabilitation of your muscle strain. Please seek their professional advice prior to self-managing your injury to avoid aggravating your muscle strain. These are general guidelines only and should not be treated as individual treatment advice.
Acute Muscle Strain Treatment
Subacute Muscle Strain Treatment
- Sub-Acute Soft Tissue Injury Treatment
- Acupuncture and Dry Needling
- Soft Tissue Massage
- Kinesiology Tape
- Supportive Taping & Strapping
- Electrotherapy & Local Modalities
- Heat Packs
Later Stage Muscle Strain Treatment Options
- Foam Roller
- Stretching Exercises
- Strength Exercises
- Closed Kinetic Chain Exercises
- Eccentric Exercises
- Proprioception & Balance Exercises
- Agility & Sport-Specific Exercises
Other Factors to Consider
- Biomechanical Analysis
- Joint Mobilisation Techniques
- Gait Analysis
- Running Analysis
- Video Analysis
What Causes Post-Exercise Muscular Pain?
What Causes Muscular Pain?
You know the feeling… dreaded “stiff and sore muscles” a day or two after you’ve done a little more exercise than usual.
Shortly after exercise begins, a mix of lactic and carbonic acids builds up in muscle tissue. These acids are waste products of muscle contractions. Don’t worry. These acids are normal. To produce “energy”, muscles burn stored glycogen. Lactic and carbonic acids are by-products of this metabolic process.
The good news is that most of these acids convert back into glycogen and are restored in preparation for your next bout of exercise. Pain and muscle fatigue can exist until the acid levels in your muscles return to normal.
How Does Massage Help?
Massage helps to eliminate the irritation caused by these acidic wastes. Research shows that massage can increase muscle recovery much quicker than rest alone.
Why is Massage So Useful When You Exercise?
Regular exercise causes many body changes. One improvement is the increase in blood vessels to the muscles to meet the demand for more oxygen and nutrients. This circulation increase helps to eliminate the waste products and toxins that build up with exercise. Importantly, it can take several weeks to develop improved muscular circulation.
Until the blood supply increases, you will have trouble with oxygen and nutrients supply. This allows toxic wastes to back up and stagnate. You will experience soreness, pain and stiffness. Many exercise enthusiasts regard aches and pains as the inevitable price to be paid. This is usually not true.
What about Muscle & Joint Stiffness?
Massage eases muscle and joint stiffness. Using massage strokes to reduce muscle tension and passive movement to stretch the connective tissue found around joints massage will improve your performance. Massage also lengthens muscle and tendon units to help prevent injuries from occurring in the first place.
What about Soft Tissue Injuries and Massages?
Massage aids recovery from soft tissue injuries such as sprains and strains. Tissue repair accelerates by increasing circulation in the injured area. Massage therapy can help speed, improve recovery, and reduce discomfort from soft tissue injuries.
Massage is Drug-Free Treatment
Massage is a drugless therapy. Headaches, insomnia, neck and back pain, digestive disorders including constipation and spastic colon, arthritis, asthma, carpal tunnel syndrome and muscular aches and pains are just some of the problems that can respond to massage therapy.