Runners aren't the most injury-prone of athletes, but they're high on the list. Here's a review of the literature telling you what to avoid
Don't be too upset if you, or one of your athletes, have had a running-related injury during the past 12 months. After all, you're in the majority. Scientific studies show that about 60-65% of all runners are injured during an average year (by definition, an 'injury' is a physical problem severe enough to force a reduction in training).
When compared to many other endurance sports, the risks associated with running are higher. For example, runners miss about 5 to 10% of their scheduled workouts due to injury, while racewalkers are absent just over 1% of the time, and step-aerobics participants conk out with a frequency of less than 1% ('Incidence and Severity of Injury Following Aerobic Training Programs Emphasising Running, Racewalking, or Step Aerobics' Medicine and Science in Sports and Exercise, vol. 25(5), p. S81, 1993).
Still, running is far from being the most injury-producing sport. In a study in the Netherlands, running ranked fourth - behind outdoor soccer, indoor soccer, and volleyball - in the total number of injuries produced per year, and when injuries were expressed per hour of actual activity, running was well down the list - in 14th place (Sportblessures breed Uitgemeten, Haarlem, DeVrieseborch, 1990).
In addition, running's 65-%-injury and 10-%-absence rates could be significantly lower if runners knew more about the actual causes of injuries and made a few simple adjustments in their training schedules. In fact, research suggests that running injuries could be cut by around 25% (Sport for All: Sport Injuries and Their Prevention, Council of Europe, Netherlands Institute of Sports Health Care, Oosterbeek, 1989).
The injury hotspots
We'll explain how to minimise the risk, but before that let's identify where injuries are likely to occur. The five anatomical 'hotspots' for running injuries are:
(1) The knee (25-30% of all injuries to endurance runners occur there);
(2) The calf and shin (20% of all injuries);
(3) The iliotibial band - a long sheath of connective tissue which runs from the outside of the hip down to the lateral edge of the knee (10% - see also SIB issue 7);
(4) The Achilles tendon (8-10% - see also SIB issue 5 ), and
(5) The foot - the focal point for hobbling injuries like plantar fasciitis (10 percent - see also SIB issue 3).
About 25% of running injuries require an actual medical consultation, and 75% of runners who seek medical care report either a 'good' or 'excellent' recovery. Two to 3% of running injuries force runners to miss some time at work (American Journal of Sports Medicine, vol. 16(3), pp. 285-294, 1988). 65% of runners report that they are running pain-free after eight weeks of treatment, and iliotibial band problems (no. 3 from above) appear to require the longest recovery period (South African Medical Journal, vol. 65(8), pp. 291-298, 1984).
'Large numbers of runners think that training speed, racing speed, running surface, and body weight are closely related to the risk of injury'
There are many misconceptions about running injuries. For example, coaches and runners often believe that males have higher injury rates than females, but male and female runners actually have about the same injury rate per hour of training (males tend to train for more hours per week, accounting for the perception that they are more injury-prone). Large numbers of runners think that training speed, racing speed, running surface, and body weight are closely related to the risk of injury, but research suggests otherwise. For instance, if you're heavier than average, you're not more likely than a lightweight runner to be injured during a typical year of training. Likewise, if you carry out most of your training on concrete roadways, you're probably not hurt more often than the runner who pads along softly on forest trails. In addition, your foot-strike pattern - whether you prefer to land on the heel or forefoot while running - doesn't necessarily have a significant impact on your injury risk (American Journal of Sports Medicine, vol. 16(3), pp. 285-294, 1988).
Another common belief is that proper warm-ups, thorough cool-downs, and appropriate stretching exercises all help to reduce injury risk, but research again says no. In a recent study, 159 Dutch runners were taught how to warm up
, cool down, and stretch effectively, while a second group of 167 similar runners received no 'injury-prevention' instruction at all. The warm-up and cool-down consisted of six minutes of very light running and three minutes of muscle-relaxing exercises, and the stretching, carried out twice a day for 10 minutes at a time, loosened up the runners' hamstrings, quadriceps, and calf muscles. However, over a four-month period, the injury rates were identical in the two groups, averaging about one injury per 200 hours of running, so the stretching, warm-ups, and cool-downs had no protective effect at all ('Prevention of Running Injuries by Warm-Up, Cool-Down, and Stretching Exercises,' The American Journal of Sports Medicine, vol. 21(5), pp. 711-719, 1993).
On the other hand, experience should make you wiser about injury avoidance or should at least give you time to strengthen weak body parts, and one recent scientific study did uncover an inverse relationship between injury risk and the number of years involved in running. In this investigation, newcomers to the sport were significantly more likely to be injured than those who had been training for many years (American Journal of Sports Medicine, vol. 16(3), pp. 285-294, 1988).
Where does it hurt?
Interestingly enough, the part of your body most at risk of injury seems to depend on your preferred race distance. Marathon runners most often suffer from foot problems, middle-distance runners specialise in back and hip maladies, and sprinters prefer to tear apart their hamstrings.
If you're a distance runner, you may be happy to know that sprinters have about double the injury rate per hour of actual training, compared to distance athletes. You may not be aware that spring and summer are the 'high seasons' for injuries, and your best direct injury predictor may be the number of miles you ran last month. This means that if May is a high-mileage month, watch out in June - your body is apparently poised for a breakdown (American Journal of Sports Medicine, vol. 15(2), pp. 168-171, 1987)
The actual injury rate per hour of running varies from study to study, but a reasonable guess is that the real rate is about one injury per 150-200 hours of running ('Prevention of Running Injuries by Warm-Up, Cool-Down, and Stretching Exercises,' The American Journal of Sports Medicine, vol. 21(5), pp. 711-719, 1993). Of course, that means that total training mileage is an excellent predictor of injury: the more miles you accrue per week, the more time you spend running and the higher your risk of damage.
'Injury risk is linked with inexperience; individuals who had been training for less than three years were more likely to get hurt'
Not surprisingly, one recent investigation found a significant upswing in injury risk above about 40 miles of training per week. This same study reinforced the idea that injury risk is linked with inexperience; individuals who had been training for less than three years were more likely to sustain injuries, compared with runners who had been involved in the sport for longer periods of time (Archives of Internal Medicine, vol. 149(11), pp. 2565-2568, 1989). Although that observation seems to contradict the idea that total hours of running are a good predictor of injury (since veteran runners tend to have more total hours), the research probably means that newcomers to the sport have a particularly hard time handling large increases in training volume.
The two best predictors of injury
Only about 50% of running injuries are actually new trouble areas; the rest are recurrences of previous problems (Archives of Internal Medicine, vol. 149(11), pp. 2561-2564, 1989). That brings to mind an important point: the absolute-best predictor of running injury is a prior history of injury. In other words, if you've been injured before, you're much more likely to get hurt, compared with a runner who's been trouble-free.
Pause for a moment on the point that 50% of running injuries are recurrences of prior maladies. This tells us that standard therapeutic approaches to running injuries (i.e., rest, icing, and anti-inflammatory medications) are effective over the short but not the long term. What's needed is a new approach in which injuries are treated not as temporary annoyances or bits of bad luck but as signs that a particular body region is not strong enough to stand up to the selected training. Once this realisation is made, injury-prone body parts can be strengthened dramatically with running-specific exercises, and the risk of a recurrence should drop.
At any rate, prior history is the best prognosticator of trouble, and the second-best predictor is probably the number of consecutive days of training you carry out (which, of course, tends to be correlated with total training volume). Consecutive days are counted as follows: If you train on Monday, Tuesday, Wednesday, and Friday, you train on three consecutive days each week (Friday doesn't count because it has a rest day before and after it).
Reducing the number of consecutive days seems to lower the risk of injury. For example, instead of running six miles every day from Monday through Friday (five consecutive days), you could reduce your risk by completing 7.5 miles per workout, four days per week (Monday, Wednesday, Friday, and Saturday, for example). Your weekly mileage would be the same in each case, but the second strategy would reduce your consecutive days from five to two, giving you much more average recovery time between sessions and a lower risk of injury (Running Research News, vol. 8(4), p. 10, 1992).
And - oh yes - some studies have shown that runners who are aggressive, tense, and compulsive have a higher risk of injury than their relaxed peers. These worried, 'Type-A' individuals also have more multiple injuries and lose twice as much training time when an injury actually occurs (Journal of Family Practice, vol. 30(4), pp. 425-429, 1990).
Sports doctors and physical therapists have come up with some novel treatments for injuries. One of the most unique therapies is the 'ice-tin' treatment for plantar fasciitis (an inflammation of the connective tissue which runs along the bottom of the foot). To treat fasciitis, keep a 12-ounce tin of non-carbonated soda or iced tea in the freezer section of your refrigerator, and roll this frozen tin under your hurting arch for 10-12 minutes at a time, several times a day. The coldness reduces inflammation, while the rolling action applies a nice stretch to your hyper-tight fascia. If you cut back on your mileage, take ibuprofen as directed by your doctor, and start the tin-rolling process early while the fasciitis is still in its infancy, you may be able to avoid making the acquaintance of an expensive set of orthotics. Don't use a carbonated-soda tin, however, or you may injure your hands trying to clean up your freezer.
Once your plantar-fasciitis symptoms have subsided, it's time for some of those strengthening exercises we mentioned. One of the best exertions for plantar fasciitis is something called 'toe pulls', also described in SIB issue 3. To carry these out, stand barefooted with your feet hip-width apart. In an alternating pattern, curl the toes of your right foot and then your left foot down and under, as though you are grasping something with the toes of each foot. Repeat this action (right foot, left foot, right foot, etc.) for a total 50 repetitions with each foot. Rest for a moment, and then complete two more sets. Try pulling yourself across the floor (smooth surfaces work best) for a distance of three to six feet as you become more skilled at this exercise. Toe pulls strengthen the muscles and connective tissues in the arches of your feet, taking the pressure off your plantar fasciae.
As you know, catastrophic injuries are uncommon in endurance runners, but the repetitive motions of long-distance running do produce lots of little strains and inflammations. Normally, these small problems develop into major difficulties only if the right steps aren't taken. The key is to develop training strategies which promote healing - not irritation - of hurting body parts. These strategies include taking more rest days between workouts (having fewer consecutive days of training), reducing mileage whenever a trouble spot arises, and carrying out plenty of running-specific strength training. If you want to toughen your training without raising your risk of injury too much, a reasonable strategy is to slightly raise your average training speed, instead of tacking on lots of additional miles.
Finally, remember that by far the best predictor of future injury is a past history of injury, so if you were hurt sometime during 2000, be careful! Your chance of an injury this year is about 50% greater, compared to the lucky runners who managed to stay injury-free last year.