The feeling of fatigue when you’re participating in sports is your body’s way of communicating that you need to ease up on the intensity of your physical activity. Dr. Wim Ament explains in a 2009 journal review in "Sports Medicine" that fatigue helps prevent you from performing exercise at an intensity and duration that could cause harm to your body. While high-intensity or long-duration sports always eventually lead to fatigue, you can help prevent it with proper conditioning and fueling.
Lack of Conditioning
Participating in sports requires a high level of conditioning in order for your muscles to be able to continue to work at a high intensity or for a longer duration. The University of Washington’s Orthopaedics and Sports Medicine department notes that a lack of conditioning can cause your muscles to weaken and thus lead to fatigue more quickly. Once participation in your sporting event causes you to work at a level or duration beyond that of which you’re conditioned, you’ll feel fatigued. This is why athletes incorporate additional conditioning work into their training regimen.
When you’re participating in a sport, your muscles require adenosine triphosphate, which fuels contractions. During high-intensity sports, such as those that require sprinting, the ATP is provided through the anaerobic lactic pathway, which is extremely limited. As a result, you hit fatigue more quickly. During lower-intensity sports, such as distance running, the ATP is provided via the aerobic pathway, which is available in larger amounts; when conditioned, you can go farther without hitting fatigue. Once the ATP is used up, you’ll feel fatigued. The body converts glucose and glycogen, which you get from food, to ATP, so ensure your blood glucose and glycogen levels are available for fuel by consuming carbohydrates prior to a sporting event. In addition, dehydration limits your body’s ability to transport fuel to your working tissues, so take in plenty of fluids before and during sport to maintain performance.
Short-term, intense exercise during sports can cause your neuromuscular system to become fatigued, and the neurotransmitters, which carry a nerve’s message to the muscles, become impaired. When the neuromuscular system becomes fatigued, it’s less efficient, and the muscle fibers contract with less force and power.
Some fatigue can be caused by outside health issues. For example, athletes with arthritis can suffer from fatigue more quickly. A lack of sleep and low levels of iron also can lead to fatigue. In addition, emotional issues, such as depression and stress, can cause you to become physically fatigued more quickly.