In theory, triathletes should have fewer overuse injuries, compared to other endurance athletes. After all, 'cross training' is believed to minimise the risk of injury (and is even prescribed for injured athletes as a way to recover), and triathletes cross train routinely. A triathlete whose main strength is running, for example, could be described as cross training for 67% of all workouts (if running, swimming, and cycling workouts occur with equal frequencies). Indeed, initial reports indicate that overuse injuries may be lower for triathletes; one study found an overuse-injury frequency of 41% in a group of triathletes, compared with the usual 50 to 65% injury rates found in 'pure' runners ('An Epidemiological Investigation of Training and Injury Patterns in British Triathletes,' British Journal of Sports Medicine, Vol. 28, pp. 191-196, 1994).
However, other research has identified a 90% (!) injury rate in triathletes, well
above the norm for endurance-sport participants ('Overuse Injuries in Ultraendurance Triathletes,' American Journal of Sports Medicine, Vol. 17, pp. 514-518, 1989). Indeed, some sports-medicine experts argue that triathletes are more prone to injury, since each of the three triathlon sports tends to trigger a particular type of malady. Swimming, for example, is known to induce shoulder injuries, which are seldom seen in running. Cycling is associated with a higher risk of lower back damage, which is usually not a problem in endurance swimmers. In addition, triathletes often carry out more total workouts per week, compared with 'straight' swimmers, runners, or cyclists. From these perspectives, triathlon competition might be considered a 'high-risk' sport.
So, the question remains: do triathletes get injured more or less often than 'specialist' endurance athletes? In addition, which triathletes are at the highest risk for injury? Do psychological state, physique, age, and gender play a role in determining risk? How about the number of years of triathlon experience, the time spent competing, training mileage, training time, number of workouts per week, training pace, and even stretching? To answer these questions, researchers at Staffordshire University in Stoke-on-Trent recently examined the five-year training programmes of 12 elite triathletes from the British National Squad, 17 national-development-team members, and 87 male club triathletes ('Injury and Training Characteristics of Male Elite, Development Squad, and Club Triathletes,' International Journal of Sports Medicine, Vol. 19, pp. 8-42, 1998). An injury was defined as any musculoskeletal problem causing cessation of training for at least one day, a reduction in training mileage, the taking of pain medicine, or the seeking of medical aid. Overuse injuries were recorded separately from traumatic injuries, such as those resulting from bicycle accidents.
And the results?
As it turned out, injury prevalence did not differ significantly between the ability groups; 75% of elite, 75% of developmental, and 56% of club athletes suffered an overuse injury during the five-year period (the downturn in injury rate in the club athletes was not statistically significant); total time taken off from training as a result of injury was also not different between groups. In addition, there was no significant difference between the three groups in the proportions of athletes sustaining injury in particular parts of the body; for example, club athletes were no more likely to sustain Achilles-tendon injuries, compared to developmental and elite triathletes. The knee, Achilles tendon, and lower back tended to be the most-injured body areas for the athletes overall. Injury occurrence was not linked to age, height, weight, or body-mass index.
As you might expect, running injuries were responsible for most of the problems, accounting for from 58 to 64% of all injuries in the three groups; cycling was far back with 16 to 34%, and swimming produced very few difficulties. A key question, then was: what factors increased the risk of running injury? The Staffordshire-University researchers were able to identify total weekly triathlon training distance (the sum of running, swimming, and cycling mileage), weekly cycling distance (!), swimming distance per week, total number of workouts per week, cycling training pace, and number of weekly running workouts (but not the running distance covered per week) as key risk factors for running injury.
Retarding muscular recovery
These findings might seem surprising at first. After all, why would an extra hour spent swimming or an extra 40k on the bike increase an athlete's risk of developing a running injury? The key, of course, is that while such efforts do not produce the kind of impact damage to muscles associated with running, they can - when carried out in large-enough volume - retard muscular recovery enough so that muscles respond less well to the stresses of running and are thus more vulnerable to being injured as a result of run training.
Triathlon training is a true 'balancing act'; workouts which improve cycling or swimming fitness can sometimes hurt running capacity or even increase the risk of sustaining a running injury. In such cases, it would be better to try to improve cycling or swimming fitness less and thus maintain the ability to run well and without injury. Progressing to higher levels of fitness in each of the three sports without having a setback in one is an extremely difficult undertaking.
So is the triathlon a high-risk sport? The 75% injury figures cited above seem high, but it's important to note that such a rate of overuse injury was observed over a five-year period; in comparison, studies have found that 50 to 65% of endurance runners are injured during just one year of training. Thus, overuse-injury frequency for triathletes appears to be relatively low, even though workout frequency often ranges from nine to 12 training sessions per week. Avoidance of a pattern of 'hammering away' in just one sport (running) and instead engaging in three different movement patterns (running, swimming, cycling) does indeed seem to be beneficial, from an injury-prevention standpoint. There are few studies comparing injury rates in triathletes with those in pure swimmers or cyclists, but the rates are likely to be higher in the former, because of the inclusion of running in the overall spectrum of activity.
Finally, since triathlon injuries tend to revolve around the knee, lower back, and Achilles tendon, triathletes should spend extra time strengthening those parts of their bodies in functional ways, ie, during movement patterns which mimic those occurring naturally in their sports.