Some people are prone to primary exercise headaches (aka, exertional headaches); many people who backpack have experienced these mostly annoying but sometimes excruciating events. Even though primarily benign, some are more ominous and require front-country medical attention; these secondary exercise headaches have an underlying cause.
If you experience an exercise headache for the first time, a physician should evaluate it for a possible underlying condition. The hiker can take action to prevent primary exercise headaches. When exercise headaches (EH) strike in the back-country, there are ways to lessen or eliminate the pain.
The current thinking is that long-duration heavy physical activity may lead to EH (Sjaastad et al., 2002). Although bilaterally throbbing in type, these headaches are relatively short duration, self-limiting, and might include nausea and vomiting like migraines (Sjaastad et al., 2003). EH is sometimes comorbid with migraine and is manageable by trigger avoidance and indomethacin (Halker and Vrgus, 2013).
Headaches to worry about
According to Doctor Paul Auerbach in his book “Medicine For The Outdoors,” worrisome headaches include ones that are made worse by breath-holding and straining; associated fever and chills; are increasing severity; of sudden onset; cause neurological changes such as weakness in an arm or leg; or any of the following: stiff neck, body rash, dental abscess, or after a head injury. It would be best if you considered a hiker with any of the prior mentioned complications for evacuation.
What triggers exercise headaches?
Some things lead to headaches in the backcountry that probably would not happen in the nice environmentally controlled fitness center. Long-duration heavy physical activity incites EH that begins during or immediately after exercise and may last minutes to 48-hours (Sjaastad et al., 2002; Upadhyaya et al., 2020).
In a study of cyclists, 26% experienced EH (van der Ende‐Kastelijn et al., 2012). The authors found that EH among the cyclists decreased with age, thus theorizing that lower intensity work was associated with lower EH rates. Further, up to 37% of cyclists used medication to control their EH. The rates of EH are 0.2 and 12.3% in the adult general public (van der Ende‐Kastelijn et al., 2012).
Rates of exercise headaches
The brain and factors that may lead to exercise headaches
The brain is a sensitive organ and is prone to exercise-induced trauma when stressed or injured. The brain accounts for about 2 to 3% of total body weight but uses up to 20-25% of total energy. The brain’s main energy source is glucose, and its metabolism is aerobic.
Several factors can stress the brain in the backcountry.
– The heat from the sun
– Dehydration and glucose depletion
– Exertion and gear
Sun and backcountry headaches
During the summer, EH is increased. The heat and humidity affect the brain and its vascular response to cooling. Solar radiation is known to penetrate the brain’s cortical surfaces and may cause some impairment in complex motor and combined motor-cognitive tasks (Piil et al., 2020). This is independent of body core temperatures. This heating of the brain may lead to EH by increasing blood flow by dilating blood vessels to enhance cooling, thus inducing vascular swelling.
Weather induced headaches?
This theoretical model for headache formation posits that extreme environmental conditions trigger a survival mechanism that motivates us to find safer environments (i.e., indoors, shade) until the weather changes. Some of the conditions include heat, high humidity, storms (changes in barometric pressure), arid conditions, or dusty conditions (Robinson, 2021).
Dealing with the sun
Keeping cool is critical; start your hike early before the intense heat of the day. Wear a hat that can protect you from the sun. Rest in the shade as much as you can. Hydrate often and effectively.
Dehydration, nutrition and exercise headaches
Dehydration has been identified as a potential trigger for exercise headaches. Water makes up 50-60% of our total body mass. Our daily fluid turnover is about 2 to 3L or 5 to 10% of total body water at rest and 10 to 12L or more with heavy exertion in hot environments (Maughan, 2003). Even modest dehydration harms brain function and health. Merely a 1 to 2% of body mass in fluid lost is associated with a decline in athletic performance, cognitive function, and increased reported headache (Maughan, 2003).
Related post: How Much Water Should You Drink on a Hike, and Why?
Nutrition on the trail is a consideration regarding EH. The brain uses 20 to 25% of the body’s total energy supply. The brain’s main energy source is glucose, and its metabolism is aerobic. It is well established that individuals with diabetes who experience hypoglycemic episodes report headache as a common symptom.
The sympathetic nervous system is critical in maintaining serum glucose levels for the nervous system, including the brain. It is asserted that headaches associated with low blood glucose levels are due to an upregulation in the sympathetic nervous system’s function to keep the brain’s energy supply adequate (Hufnagl & Peroutka, 2002). Given this, the hiker’s diet needs to replenish blood glucose stores to prevent exercise-induced hypoglycemia and possible headache.
Prevention of EH through hydration and feeding
Starting hikes prehydrated and well-fed is of utmost importance. Beginning a hike in a mildly dehydrated state will significantly increase the risk for dehydration. Using a carbohydrate-based sports drink will help maintain blood glucose levels. Grazing as you hike rather than waiting for a “lunch break” will help keep blood glucose and energy level. Eat sufficient calories.
Drink fluids regularly to prevent dehydration. Use drinks with electrolytes to avoid electrolyte depletion and exercise-associated hyponatremia (EAH). EAH is a condition that occurs when a person drinks too much plain water, which may reduce blood sodium levels. In rare instances, it can be fatal. Water loss with heavy physical exertion can reach 6600 mL (Auerbach, 2009/2016), equal to 223 oz! Along with oral fluids, ingesting fruits and vegetables provide valuable sources of fluids with vitamins and minerals (National Strength & Conditioning Association, 2011).
Use your urine color to judge your hydration level. Urinating frequently is a good sign of hydration level with a frequency of about two hours adequate (Reuter, ed., 2012)
Use the urine color chart to gauge hydration status.
Altitude-related headaches are worth mentioning. Even though not directly related to exercise, I feel it is part of the melee in backcountry headaches. When making rapid ascents to altitudes of 8202′ (2500 m), altitude-related problems may occur. The most common range for severe high altitude illness is between 11,483 to 18,045 ft (3500 to 5500 m) (Auerbach, 2009/2016), including headache.
Climbers should take high-altitude headaches (HAH) seriously as this (and many others) can be a symptom of high altitude cerebral edema or precursor to acute mountain sickness (Auerbach, 2009/2016). Headache alone should be treated as a HAH and be completely resolved before a climber moves any higher on the mountain.
It is unclear what causes HAH, but risk factors include migraine history, low arterial oxygen saturation, high ratings of perceived exertion, low fluid intake (Burtscher et al., 2011), acclimatization, cellular hypoxia, genetic factors (Marmura & Hernandez, 2015). Older age is inversely related to HAH (Silber et al., 2003).
The main preventative measure a climber can take is avoiding sudden ascent to a sleeping altitude of over 9843 ft (3000 m) (Auerbach, 2009/2016). Following prescribed ascent protocols is key. Staying hydrated and well-fed and adding rest days on the climb.
If HAH occurs treat to complete resolution before moving any higher on the mountain.
Exertion and gear
EH is associated with prolonged high-intensity exercise. Some evidence shows that activity involving intense abdominal and chest movements triggers exercise headaches (Jarvis, 2006) and could be due to high intra-abdominal pressure and intrathoracic pressure. However, high intra-abdominal pressure and intrathoracic pressure via Valsalva-maneuver improve athletic performance, stabilize the trunk, unload the lumbar spine, and prevent injury (Blazek et al., 2019). Valsalva-type breathing may lead to vascular brain injuries, especially in people with lower fitness, hypertension, cardiovascular disease, or extreme body overload (Blazek et al., 2019).
Poor-fitting backpacks that are not made for the activity and misloaded packs can strain the spine and the shoulders, affecting the entire body up and down the kinetic chain (Manning-Schaffel, 2021). These problems with backpacks may lead to altered posture on and off the trail. The strain of muscles, particularly in the neck and shoulder regions, can lead to headaches (Manning-Schaffel, 2021).
Dealing with exertion and gear issues
Get fit. Hiking is a great way to get fit. But adding some in the gym training will help develop the agility, strength, power, and aerobic fitness needed to travel in the backcountry safely. Develop functional core strength with a well-rounded resistance training program.
Learn how to fit and use a backpack properly. The success of your hikes and backpacking outings is partially dependant on having and properly using good equipment. Watch the video below on “Fit a Backpack Right.”
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Blazek, D., Stastny, P., Maszczyk, A., Krawczyk, M., Matykiewicz, P., & Petr, M. (2019). Systematic review of intra-abdominal and intrathoracic pressures initiated by the Valsalva manoeuvre during high-intensity resistance exercises. Biology of Sport, 36(4), 373–386. https://doi.org/10.5114/biolsport.2019.88759
Burtscher, M., Mairer, K., Wille, M., & Broessner, G. (2011). Risk factors for high-altitude headache in mountaineers. Cephalalgia, 31(6), 706–711. https://doi.org/10.1177/0333102410394678
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Manning-Schaffel, V. (2017, September 25). Why Our Bags Are Wrecking Our Backs. NBC News; NBC News. https://www.nbcnews.com/better/health/why-bags-are-wrecking-our-backs-ncna803541
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Piil, J. F., Christiansen, L., Morris, N. B., Mikkelsen, C. J., Ioannou, L. G., Flouris, A. D., Lundbye-Jensen, J., & Nybo, L. (2020). Direct exposure of the head to solar heat radiation impairs motor-cognitive performance. Scientific Reports, 10(1), 7812. https://doi.org/10.1038/s41598-020-64768-w
Reuter, B., & National Strength & Conditioning Association (U.S. (2012). Developing endurance. Human Kinetics.
Robinson, J. (2019, August 18). Barometric Pressure Headaches, Migraines, and Weather. WebMD. https://www.webmd.com/migraines-headaches/headache-and-migraine-trigger-weather
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Upadhyaya, P., Nandyala, A., & Ailani, J. (2020). Primary Exercise Headache. Current neurology and neuroscience reports, 20(5), 9. https://doi.org/10.1007/s11910-020-01028-4
van der Ende‐Kastelijn, K., Oerlemans, W. and Goedegebuure, S. (2012), An Online Survey of Exercise‐Related Headaches Among Cyclists. Headache: The Journal of Head and Face Pain, 52: 1566-1573. https://doi.org/10.1111/j.1526-4610.2012.02263.x
Silber, E., Sonnenberg, P., Collier, D. J., Pollard, A. J., Murdoch, D. R., & Goadsby, P. J. (2003). Clinical features of headache at altitude: A prospective study. Neurology, 60(7), 1167–1171. https://doi.org/10.1212/01.wnl.0000055876.26737.b9
Backwoods wanderer with a passion for backpacking, hiking, kayaking, and exploring the wilds of the Catskills and Adirondacks in New York. A Catskill 3500 Club Member and Adirondack Forty-Sixer. Climbed Mount Rainier. Professionally an Exercise Physiologist.