Relentless Forward Progress_ A Guide to Running Ultramarathons - Bryon Powell [74]
Heat cramps are muscle pains or spasms that usually occur in the arms, legs, or abdomen caused primarily by sweat loss. They can be treated with rehydration or regaining electrolyte balance as well as a reduction in activity and body temperature. Heat cramps can be a symptom of heat exhaustion.
Heat exhaustion is expressed in an array of symptoms, including heavy sweating, paleness, muscle cramps, tiredness, weakness, dizziness, headache, nausea or vomiting, and fainting. Increased heart rate, low blood pressure, as well as fast, shallow breathing may also indicate heat exhaustion. Drinking cold beverages, resting, and applying cold water to the body cool a person suffering from heat exhaustion. If the symptoms are severe or last for more than an hour, seek medical attention.
Heatstroke, which occurs when the body can no longer control its temperature, is the most serious of the heat illnesses. It can lead to permanent health complications and death. With heat exhaustion, the body stops sweating, which leads to a spike in body temperature, possibly up to 105 degrees F in just 10 to 15 minutes! Symptoms include an extremely high body temperature, red, hot, and dry skin with no sweat, a strong, rapid pulse, a throbbing headache, dizziness, nausea, confusion, and unconsciousness. In the case of heatstroke, contact emergency services immediately. Next, take the victim to a shady area and cool the victim as rapidly as possible. Place him or her in a body of cool water, if possible. As an alternative in dry climates, place the victim in light clothes or a light sheet doused in water for evaporative cooling.
Avoid Being Low at High Altitude
Ultrarunning calendars are filled with high alpine races just begging to be run. The problem? Most people live within a few thousand feet of sea level, which means their bodies are not acclimated to high altitude. As with heat, running at high altitude without acclimation can affect both health and performance. The body and, in particular, the cardiovascular system undergo a multitude of changes when presented with significant increases in altitude. We’ll only look into those changes that are most relevant to a lowland runner ascending to moderate to high altitudes (7,000 to 14,000 feet) to run an ultramarathon. This section looks at some of the body’s adaptations to high altitude, issues faced when arriving at altitude, and rare but serious health complications that can arise at high altitudes.
High altitude shouldn’t stop you from running. Just know how to stay safe. (Photo by author)
The Effects of Altitude
Hypoxia, or lack of oxygen, is the primary reason for performance degradation at altitude. The amount of oxygen in the atmosphere decreases logarithmically with increases in altitude. This means that aerobic performance, which is oxygen-dependent, is unaffected below 3,000 feet and minimally affected below 6,500 feet. Above 6,500 feet aerobic performance quickly worsens as altitude increases further. The impact of hypoxia also worsens as race length increases. Hence, running races like the Leadville 100-mile, which starts above 10,000 feet and tops out at 12,600, are an extreme challenge.
One the body’s quickest adaptations to high altitude is a gradual increase in ventilation, the volume of air respired, over the course of hours and days of arrival. The increase in ventilation has a nearly linear relationship with arterial oxygen saturation, a measure that indicates how close blood is to being fully oxygenated. The more oxygenated your blood, the more that’s available for your muscles. For a sea-level runner, the vast majority of ventilatory acclimation occurs within four days of ascending altitudes