7 Types of Running Pain and the Science Behind It
The reasons runners hit the pavement are diverse. Some want to get fit, others want to lose weight and some have a goal of completing a marathon or other race. Although each runner is vastly different, he or she all has one thing in common: running hurts each person in the same way. Although far from being a contact sport, running is considered by many to be the most painful of activities. From the searing lungs to the burning muscles and inability to get out of bed in the mornings, many people may question the sanity of the common runner.
In an ideal runner’s world, even a 100-mile race would be 100% pain-free. No twinges, no aches, no lingering soreness from the last workout. Truth is, there are plenty of runners out there who constantly fight with a slight disturbance – a whiny knee, a tight hamstring or a tender foot. While these issues often are not serious enough to cause a time-out, they can become truly annoying, especially when you can’t train at your maximum nor fully enjoy your running.
The secret behind running pain is to think of it in terms of a long spectrum.
There is the red zone at one end, with severe injuries such as stress fractures, and there is the green zone at the other end, with mild aches that annoy you one day and disappear the next. The bad news? Most runners are stuck right in the middle, the not-quite-injured and not-quite-healthy, yellow zone.
Whether you linger in that yellow zone, return to the green or land in the red end of the spectrum depends much on how you handle the first stab of pain. The science behind running pain is simple. You have to take a short time off now or plenty of time off later.
There is one easy way not to end up in the red end. The key is to reduce your mileage, decrease the intensity of your trainings, and create a long-term injury-prevention plan (with strength training and stretching).
I bet nobody likes physical therapy, yet the pain will always come back if one don’t pay close attention to his or her body.
Origins of Pain
Pain is mainly based on the human body’s perception of threat. Evolution has taught our brains that pain is necessary, as it helps protect us from damage. If you touch a hot stove with your fingers, your brain wants you to feel pain so that you don’t suffer severe consequences. If you tear a tendon or a muscle, you will go through terrific pain, a necessary reminder to stop using the injured limb.
There is a great problem with running, especially when your brain keeps telling you “ouch” after the tissue has been completely healed. We’ve all been there, beginners or seasoned runners. After each injury, your body retains discrete memories of those painful experiences. TheoriesTherefore, you may encounter little pains during a long run, but that doesn’t mean you are injured.
What causes the pain that can stop a runner in his tracks, forcing him to hunch over and gasp for breath? The following examines seven different types of pain, and the physiology of what is happening inside the runner’s body.
1. Runner’s Knee
Also called patellofemoral pain syndrome (PFPS), runner’s knee got its nickname for a very unfortunate and obvious reason – it’s quite common among runners. Running causes irritation where the patella (kneecap) rests on the thighbone. The pain is usually dull and chronic or sharp and sudden. While running biomechanics can be blamed, the cause can also be traced back to tight hamstrings and conditioned quadriceps. Since weak quads can’t support the kneecap, this leads to pressure on the knee. One of the easiest ways to avoid another bout with PFPS is by adding stretching and strengthening to your routine.
Theories about the physiology underlying the pain have come and gone. There is a reason why all of these proposed etiologies can’t stand for too long, as researchers found no structural abnormality associated with patellofemoral pain syndrome. Recently all studies performed with x-ray, surgical arthroscope or MRI have lead orthopedists to a new view in which the pain itself comes from a chronic stimulation of pain nerves in the knee. This could be the essence of the runner’s knee.
Minor tissue degradation like the inflammation of the synovium, a pouch that holds the knee’s lubricating fluid, may be the cause of this nerve stimulation.
Any tips about treatment? Target the pain by avoiding running and anything that causes pain in your knee. You can power walk or even jog as long as you do it pain-free. By using this approach you will enable the target tissue to restore its homeostasis (the natural equilibrium state), and you will keep the knee adapted to the stress caused by running.
Increase your running gradually and keep an eye on the pain level. Reverse the process whenever soreness emerges.
Don’t get sad if you have runner’s knee. It’s a very minor condition and as studies have found, it really is just a chronic inflammation of tissues within the knee. Calibrate your running distances according to your experience and fitness, and you will have no issues. However, know that it can become a serious breakdown if you continue training and do nothing to minimize the impact.
2. Side Stitches
All runners will experience a side stitch at some point in their lives, whether during a recreational run or a race. Characterized by an intense stabbing sensation under the rib cage, the side stitch, formally called exercise-related transient abdominal pain (ETAP), has no definitive cause. Although researchers once thought side stitches were brought on by dehydration, a study found that each runner who was not given any liquids, water, nor sports drinks during exercise had an equal chance of developing the dreaded ETAP.
The most recent and generally accepted theory developed by sports physiologists is that the diaphragm, which is a large muscle at the base of the rib cage that expands and contracts to help regulate the intake of air into the lungs, is to blame. When a person is running, the diaphragm works harder than at rest. Even a slight strain in the ligament that connects the diaphragm to the abdominal muscles can cause severe muscle cramping, resulting in a side stitch.
Preventative measures for ETAP include core strengthening and stretching.
3. Muscle Cramps
The pain and cramping that often affects large muscle groups in the legs, such as calves, hamstrings, and quadriceps, is most often caused by the production of lactic acid within the muscles. Throughout the day, oxygen is used as the main driving force to perform glycolysis, which is the breakdown of glucose (sugar) into energy.
Glucose that has been stored in the muscles as a result of eating carbohydrates is converted into pyruvate, an important metabolite, which is used in slow-moving energy conversion processes. However, during hard anaerobic exercise (i.e. exercise that induces heavy breathing, such as running), muscles require energy at a faster rate than can be delivered by traditional oxygen-carrying pathways.
During hard workouts, glycolysis in the absence of oxygen is performed by converting pyruvate into lactate, which in turn quickly breaks down more glucose for immediate muscle consumption. This cascading process delivers energy more quickly than during aerobic activity, but does so at the cost of lactate build up within the muscular system.
The presence of lactate increases the acidity within the muscle groups, and also disturbs the body’s normal production of other necessary metabolites. Only when the body slows down and returns to aerobic activity (such as walking) is the typical aerobic pathway for shuttling pyruvate for energy consumption restored. However, the change in acidity within the muscles decreases the efficiency of this process, which results in the feeling of decreased energy.
The pain associated with lactic acid build up is not caused by the presence of lactate in the muscles. It is caused by the production process of converting pyruvate into lactate and the disruption of the muscle’s normal metabolism. Interestingly, this process is the body’s defense mechanism used to slow down the body to ward off muscular damage. By causing pain, the body is forced to return to aerobic activity, jumpstarting muscle recovery by immediately converting the remaining lactate into pyruvate for energy consumption.
4. Stress Fracture
We have just arrived in the depth of red zone pains. Stress fractures are for runners like severe earthquakes are for big cities. When the athlete puts great stress on his body, the damage might be too much for the body to repair, potentially ending a runner’s career.
Stress fractures are small, microscopic breaks in a bone caused by the repeated forces during exercise and occur in the outside portion called the cortex. They are not caused by trauma. Usually, forces come from running impacts or from tendons and muscles pulling very hard on the bone. It’s simple physiology. When the bone is constantly under huge pressure it will eventually become weak. While it’s true that the body keeps up with such stresses caused by running by generating osteoblasts, cells that make bones, that threshold can be be left behind and that is when pathology starts.
Left untreated, that severely-injured bone can break.
When it comes to stress fracture risk, bone density, shoe condition, muscle condition and bone shape all have a role. Studies show that female and beginning athletes bear the highest risk. The most common stress fracture bone? The tibia.
Diagnosis is difficult as stress fractures are quite rare, yet they can be caused by different factors. The main symptom is a deep pain that usually worsens throughout a run. The key is to not make a minor stress fracture get worse.
5. Searing Lungs
Running makes you breathe rapidly and forces the lungs to work very hard to get the necessary amount of oxygen for the body.
No matter the level of runner, each has experienced the telltale burning sensation in his lungs that feels reminiscent of holding his breath. When a runner takes air into his lungs, the oxygen is converted into carbon dioxide, which is expelled when he exhales.
However, as a runner’s breathing becomes heavier during exercise, he will have a more difficult time efficiently expelling the carbon dioxide that is rapidly accumulating. The burning sensation is caused by the same response that reminds a person to breathe when holding his breath, which is the buildup of carbon dioxide in alveolar tissue. As runners become more efficient athletes, their ability to expel carbon dioxide improves.
I will now explain the physiology of why lungs hurt during and after running.
Using your mouth to breathe during running can cause pain in your lungs because your brain actually thinks CO2 is being lost in excess. Your body produces a type of cells called goblet cells. They produce mucus, which exponentially slows your breathing and quickly constricts your blood vessels.
The excess mucus and vasoconstriction will make your breathing more difficult, resulting in a very painful burning sensation. Have no worries, the phenomenon is usually temporary and it will go away as you gain more and more experience with running.
Pay attention: there is also a pathology called exercise-induced asthma. It is a chronic condition generated by narrowing of the airways and inflammation. If you have asthma, see a physician as soon as possible.
6. Delayed Onset Muscle Soreness (DOMS)
Researchers have found that the muscle soreness and weakness experienced 24 – 72 hours after exercise (i.e. the reason a runner is unable to walk down a flight of steps for a few days post-marathon) is not caused by lactic acid build up, as originally thought. The pain appears to be the result of muscle cell damage and an increased release of metabolites during strenuous exercise.
Delayed onset muscle soreness is most commonly associated with eccentric motion of the muscle with heavy loading, such as would occur in downhill running. The body issues an inflammatory response to repair the muscle damage, which is the cause of painful soreness and swelling. Researchers are presently exploring ways to mitigate the inflammatory response with use of anti-inflammatory medications.
However, preliminary research suggests that these medications can inhibit muscle repair, so although the pain is gone, the healing process will be slowed down. For now, the RICE (rest, ice, compression and elevation) treatment method seems to be the only reliable way to counteract pain associated with the damage.
7. Lactic Acid Buildup
The popular belief says that lactic acid is just a waste product that “builds up” in your muscles during exercise, leading to stiff muscles and fatigue. It is an inaccurate and distorted version of the real story, one could say.
The truth is, pain is produced by a substance called lactate, which is involved in muscle function and plays a key role in the production of ATP (energy) to fuel the muscle. Lactic acid is something completely different, another chemical compound that does not come into play.
Glucose is broken down by the human body to create energy, and that’s the point when pyruvate (an acid) is produced. Pyruvate is converted into lactate, and lactate is converted into energy. The amount of glucose that is not used is turned into glycogen, another important element in the muscle-building process.
When you exercise too much your body produces a lot of pyruvate and lactate. The conversion process can be quickly overwhelmed. Although plenty of research has been done to find out what exactly causes fatigue during exercise, no one knows a specific answer. There is a theory which suggests that hydrogen ions elevate the acidity when released into the bloodstream. This leads to fatigue.
What’s more, lactate does not cause post-exercise soreness. It actually comes from the muscle damage that results from intense workouts.
Why you should understand the science of pain in running
There is no argument that running is a painful, yet extremely efficient, form of exercise. Despite the pain, or perhaps because of it, runners enjoy the process of becoming fit and fast. Many runners admit that the fun is not in running, but in the feeling of stopping. An understanding of the science behind the pain may not necessarily make the discomfort go away, but can give the athlete a better appreciation for the intense work his body is performing.
Embrace pain and you will master the art of running.