This time of year may find you chomping at the bit to ramp up your outdoor running routine. Maybe you’re training for a marathon or other distance race. Or perhaps you just want to shave off a few pounds, enhance your overall health or reduce stress through exercise.
Running is increasingly popular because it doesn’t require expensive equipment, and it can be done practically anywhere,” says Shane McClinton, D.P.T.’07, M.S.P.T.’01, a physical therapist with the DMU Physical Therapy Clinic. That growth in the running industry means the rate of injuries is also increasing, he says. In fact, research estimates that 37 to 56 percent of runners experience an injury in any given year; among those training for marathons, the incidence of injury can be as high as 90 percent. Knee injuries are most common, followed by problems with the foot and ankle, lower leg, hip and pelvis, the Achilles tendon and calf. Avoiding these problems can be a challenge.
“The etiology of a running injury is multifactoral, and each runner has his or her own threshold for injury,” McClinton notes. “The cause of injury may not be addressed simply by static alignment, mechanics, footwear, terrain or training. The human body is very complicated and has an amazing capacity to compensate in both good and bad ways in response to internal and external stresses.”
Unfortunately, research on running is inconclusive on what exactly provokes injuries and what to do to prevent them. McClinton says some evidence indicates runners with overall weekly mileage of more than 20 miles but fewer than 40 seem to have a lower rate of injury.
Previous injury, especially one from which a runner hasn’t fully recovered, is one of the highest predictors the athlete will get hurt again. Other factors include a higher body mass index – a measure of body fat based on height and weight– and over-pronation – the otherwise normal part of the gait cycle that occurs as the foot rolls inward and the arch of the foot flattens, to help absorb shock at the foot.
However, less evidence exists proving that age, running experience, stretching and flexibility exercises, terrain and even footwear prevent injuries. “From a rehabilitative standpoint, we know steps like strengthening certain muscles can help,” McClinton says. “But we know of few isolated and universal risk factors indicating how to avoid injury.”
So what’s a runner to do? McClinton offers the following advice.
• Know thyself and what your body can do. Design your training program based on your past and current physical activity. When increasing your distance, do so by increasing your overall weekly volume 10 to 20 percent, and listen to your body.
• Equip your feet: Current methods of matching different shoe types or orthotics based on static foot characteristics have not been shown to reduce injury risk or lead to better recovery outcomes. Many experts agree that your perception of comfort after trying on different shoe styles may be a reasonable approach to finding the best footwear. Shop for shoes at an athletic store with knowledgeable staff, and find out if it has an exchange policy for you to assess the fit and feel of the shoe outside of the store.
• Include exercises to strengthen your feet in your workout routine. Use your toes to crunch a towel and pick things up. Try raising your big toe while pushing your other toes down; then reverse. Some people can benefit from a very gradual progression of barefoot activities such as walking or jogging in sand or grass. If you are unsure that you will tolerate barefoot activities or exercise, consult an appropriate health care provider.
• If you experience pain that goes beyond sore muscles and doesn’t dissipate within 24 to 48 hours, seek treatment. Untreated injuries often get worse and can affect other parts of the body. As you recover, be sure to return to your running program gradually.
• Consult your health care provider to plan and evaluate your training. Ideally, find a professional with experience in working with runners and other athletes for advice on exercise, technique, performance enhancement and nutrition.
“I’m biased, but musculoskeletal and movement-related function and injury are our areas of expertise as physical therapists. That’s where we fit in the health care system,” McClinton says. “If we see indicators of a nonmusculoskeletal condition, we’ll send you to the appropriate health care provider. It’s all about helping the individual patient and collaborating to meet his or her goals.”
DMU experts run the numbers on
long-distance running
55-60° F the optimal outdoor temperature for running a marathon
Julia Moffitt, Ph.D., assistant professor of physiology and pharmacology, explains: If the temperature is warmer, you will compromise your performance in an effort to keep your body cool. This is because your body must divert blood flow from working skeletal muscle to the skin in order to dissipate the heat. The lower blood flow to the working muscles will reduce your running performance. Regardless, you need to stay hydrated; fluid replacement drinks like Gatorade are highly recommended to replace electrolytes lost during sweating. The hotter and more humid it is, the more critical it is to replace those fluids and electrolytes.
1,300 the number of suggested miles to run the year before running a marathon
Shane McClinton, D.P.T.’07, M.S.P.T.’01, DMU physical therapist, explains: To build a good base for marathon training, a runner should be able to tolerate 25 miles per week for up to a year.
2,600 the number of calories an average person burns running a marathon
Moffitt explains: A good rule of thumb is that the average person burns approximately 100 calories per mile. So running a full marathon would burn about 2,600 calories. Faster runners are burning more calories per hour, but they complete the marathon faster, so it’s about equivalent energy expenditure for a given distance.
160 heartbeats per minute for an average person while running a marathon
Moffitt explains: An average resting heart rate is about 55 beats per minute (BPM). A person in his/her 20s might have a maximum heart rate of 200 BPM. Most individuals run a marathon at 65-80 percent of their maximum heart rate. The higher the percentage of maximum heart rate a runner can maintain for a prolonged period, the faster he or she can complete a marathon. The primary determinant of that is how fast an individual can run without accumulating lactate, or at what percentage maximum heart rate his/her lactate threshold occurs. World-class marathon runners have a very high lactate threshold, near a 90-95 percent maximum heart rate, which allows them to run at a very fast pace for longer than an average person.
36 milliliters of oxygen consumed per kilogram of body weight each minute
Moffitt explains: Someone running six miles per hour (equivalent to a 10-minute mile) will consume approximately 36 milliliters of oxygen per kilogram of body weight each minute. Athletes often have their maximum oxygen consumption measured; this is called a VO2 max. The higher one’s VO2 max, the greater that person’s running performance.
