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What is the background?
What is an injury rate?
Injury rates provide one good measure of understanding how likely you are to incur an injury when taking part in a sporting pastime. Rates are very typically expressed in terms of injuries per 1,000 hours of training. So as long as you know roughly how much time you are going to spend training, it gives you an idea of your exposure. Obviously, if you are going to compare two different sporting pastimes with very different training volumes, you will need to scale one to the other. Injury rates are quite useful when the researchers only have access to small samples of subjects (such as is often the case in sporting pastimes) but where each subject records their training hours.
Other common measures of how likely you are to incur an injury when taking part in a sporting pastime are injury incidence and injury prevalence. Injury incidence is the percentage of the population who experience an injury over a certain time period. This time period is highly variable and can be over short or long periods of time (e.g. a month or a year). On the other hand, injury prevalence is the percentage of the population who are currently injured at any given time. Depending on the duration of the injury and the measurement period of injury incidence, injury prevalence can be smaller, similar to, or larger than injury incidence. Injury incidence and injury prevalence are most useful when the samples of the population being studied are reasonably large.
Why consider injury risk in sports?
All physical activity involves a certain risk of injury, whether acute (traumatic) or chronic (overuse). For elite amateur and professional athletes, these risks are accepted in return for the ultimate reward that comes from successful participation at the highest levels. Indeed, many such athletes may not have much choice in the type of sport that they happen to excel at. On the other hand, for non-elite amateur athletes and individuals who make use of participative sport for the purposes of exercise, injury rate (as well as enjoyment) should be an important factor in deciding which type of sport to take part in. Some of the most popular amateur sports are long-distance running, cycling and triathlon. It seems that many of the general population regard such sports as fairly “safe” options to participate in, while strength sports are typically considered more likely to cause injury.
What are the injury rates in common sports?
Injury rates are not reported in all common participative sports so it is hard to give a comprehensive picture. Long-distance running was one of the first sporting pastimes to be extensively explored. Early reviews of the literature in long-distance running quite found that injury rates ranged from 2.5 – 12.1 injuries per 1,000 hours training (Van Mechelen, 1992). Recent studies support injury rates in long-distance running at the top end of this range (Hespanhol, 2013). And researchers investigating triathlon and have found rates around half as high as in solely running, from 1.4 – 5.5 injuries per 1,000 hours training (Korkia, 1993; Zwingenberger, 2014). These findings may imply that not focusing solely on one activity is less injurious from an overuse perspective, or it may imply that swimming and cycling are fundamentally less damaging than running. It is currently hard to tell which factor might be most important.
What are common training loads?
Generally, training volumes are thought to be higher in endurance sports than in strength sports. However, this does not always appear to be the case and may actually be modality-dependent. For example, one group of male recreational marathoners reported performing an average of just 4.5 hours of training per week (Tanda, 2013) and a group of recreational female half-marathoners reported running just 3.2 hours per week (Knechtle, 2011). These training volumes appear similar to those used in strength sports. On the other hand, a recent cycling study reported that club-level cyclists rode on average 10.3 ± 8.7 hours per week (Dahlquist, 2014).
What is the rate of injury in strength sports?
Turning to the point of this article, the rate of injury during various strength sports, including strongman, powerlifting, Olympic weightlifting, bodybuilding and other types of competitive strength-related activities is summarized in the table below and set out in the following studies. Studies were only included in this review where an injury rate per 1,000 hours of training was calculated and presented.
If you are curious about the exact parameters of each of these studies, you can read brief summaries in the following section. Otherwise, you can skip down to the analysis later on.
Winwood (2014) investigated the incidence of injury and their locations during strongman training and competition. They recruited 213 strongman athletes with 12.8 ± 8.1 years resistance-training experience and 4.4 ± 3.4 years strongman experience and asked them to complete a 1-year retrospective survey of injury. Injury was defined as any physical problem that caused a missed or modified training session or competition. The researchers found that 82% of the subjects reported at least one injury over the year in question and the injury rate was 5.5 injuries per 1,000 hours of training. In terms of region of injury, the most common locations were: low back (24%), shoulder (21%), bicep (11%), and knee (11%). The researchers observed that strongman athletes were 1.9 times more likely to sustain an injury when using strongman implements than when using traditional resistance-training methods.
Siewe (2014) assessed the risk of injury during training for competitive bodybuilding by collecting questionnaires from 71 competitive and elite bodybuilders. They found that 45.1% of the subjects reported some symptoms of physical injury while training but the overall injury rate was just 0.24 injuries per 1,000 hours of training. The most common regions injured were the shoulder, elbow, lumbar spine and knee. The researchers concluded that injury rate is low compared to other weightlifting disciplines such as powerlifting, Olympic weightlifting or strongman.
Siewe (2011) assessed injury incidence in 245 competitive and elite powerlifters from 97 incorporated powerlifting clubs by way of a questionnaire. They found that 43.3% of powerlifters complained of injury-related problems during workouts. However, the injury rate was 1.0 injuries per 1,000 hours of training. The most commonly injured regions were the shoulder, low back and knee. Interestingly, the researchers found that the use of weight belts led to greater risk of injury at the low back.
Eberhardt (2007) assessed the risk of injury during training for recreational (non-competitive) bodybuilding. They found that the rate of injury was 1.0 injuries per 1,000 hours but they did not define injury as physical damage leading to time-loss.
Keogh (2006) assessed injury incidence in 82 male and 19 female competitive open and masters powerlifters over a 1-year period. They defined injury as any physical damage leading to a missed or modified training session or competition. The injury rate was 4.4 injuries per 1,000 hours of training and the most commonly-injured body regions were the shoulder (36%), low back (24%), elbow (11%), and knee (9%).
Raske and Norlin (2002) investigated the incidence and prevalence of injuries among both elite Olympic weightlifters and powerlifters in both 1995 and in 2000. Across both sports and across both time periods, the subjects incurred 2.6 injuries per 1,000 hours of training. In 1995, the most commonly-occurring injury location was the low back but in 2000, the most commonly-occurring injury location was the shoulder. The researchers observed that the Olympic weightlifters tended to experience low back and knee injuries, while the powerlifters were more prone to shoulder injuries.
Calhoon (1999) assessed the incidence and nature of injury among elite US male weightlifters training at United States Olympic Training Centers over a 6-year period. The researchers found that the rate of injury was 3.3 injuries per 1,000 hours of weightlifting exposure. They noted that the most commonly-occurring injury locations were the back (primarily low back), knees, and shoulders.
Haykowsky (1999) assessed the incidence and nature of injury among 11 elite blind powerlifters (9 males and 2 females). They reported that the rate of injury was 1.1 injuries per 1,000 hours of training and they noted that the most commonly-occurring injury locations were equally the low back and shoulders.
Quinney (1997) assessed the incidence and nature of injury among 31 elite powerlifters. They reported that the rate of injury was 3.7 injuries per 1,000 hours of training and they noted that the most commonly-occurring injury location was the low back.
Brown (1983) assessed the risk of injury in adolescent powerlifters by way of a questionnaire in 71 contestants entered in the 1981 Michigan Teenage Powerlifting Championship. The researchers found that the average subject had participated in 4.1 workouts per week for 17.1 months wherein each workout lasted 99.2 minutes. Since 98 powerlifting injuries occurred during this time, the rate of injury was 0.85 injuries per 1,000 hours training. The researchers found that the low back was the most commonly-injured area.
Hak (2013) assessed the injury rates and profiles of subjects participating in a popular high-intensity power-training program using resistance-training exercises (CrossFit), with an online questionnaire. The researchers collected 132 responses of whom 97 individuals (73.5%) reported sustaining an injury during this type of training. Several individuals reported sustaining more than one type of injury and a total of 186 injuries were reported, of which 9 needed surgery. The researchers found that the injury rate was 3.1 injuries per 1,000 hours of training. They noted that the most commonly-injured region was the shoulder, followed by the back.
What is the rate of injury in strength sports?
From the above studies, it should be fairly clear that the risk of injury (whether acute or chronic) is not higher when training for strength sports than when performing endurance-type training such as running or triathlon. The rate of injury ranges between 0.24 – 5.5 injuries per 1,000 hours of training.
How does this rate compare to endurance sports?
In comparison to the overall rate of injury in strength sports of between 0.24 – 5.5 injuries per 1,000 hours of training, the rate of injury during long-distance running is around 2.5 – 12.1 injuries per 1,000 hours and the rate during triathlon is around 1.4 – 5.4 injuries per 1,000 hours training. Thus, strength sports are certainly no more injurious than those endurance activities that have been investigated widely.
Where are the most commonly-injured regions?
We can see that the most commonly-occurring injury locations for strength athletes are the low back and shoulder. It is tempting to consider that the Olympic weightlifters and strongman athletes are more prone to low back injury and that the powerlifters and bodybuilders are more prone to shoulder injury but this conclusion seems a little premature based on the available literature.
Which strength sports put athletes at greatest risk of injury?
The relative risk associated with participation in different strength sports is unclear. Few studies assessed more than one strength sport concurrently. Therefore, is possible that differences between study injury rates during training could have arisen from study artefacts (i.e. things like the exact way an injury was defined, or the precise population, etc.) and not from the type of strength sport being studied. Nevertheless, if we are to draw any conclusion about the relative risks associated with injury rate in strength sports, it is that bodybuilding training is less injurious than training for other strength sports.
Exactly what aspects of the bodybuilding training approach mean that it is less dangerous are unclear. Various rationales have been suggested. In their study, Siewe (2014) proposed that bodybuilding tends to use slower and more controlled movements, as well as smaller loads. In their review, Fisher (2014) picked up on similar ideas and also suggested that these training variables might be important modifying factors for injury. Additionally, it is possible that there are differences in the risk of injury associated with training using free-weights versus training using machines. However, such factors remain to be explored in long-term trials and we cannot make any conclusive statement about these factors at the present time.
What does this mean for the general population?
For the general population, we might expect training injury rates to be lower if bodybuilding-style methods were adopted, in comparison to powerlifting-, strongman- or Olympic weightlifting-style training methods. However, this would need to be confirmed in populations of non-athletes, preferably by monitoring multiple groups to avoid the effects of study artefacts.
What does this mean for the athletic population?
For the athletic population, it is an interesting question to consider whether incorporating some elements of bodybuilding practices would lead to a reduction in injury rates during training. Of course, the major two unknowns would be the effect on performance and the impact on injury rates during competition. To the best of my knowledge, there is no research in either of those areas so it would be purely speculative to assess whether the risk-reward of incorporating such methods would be better or worse than existing practices.
What are the practical implications?
Training for strength sports is associated with similar or lower rates of injury than training for endurance sports such as long-distance running and triathlon. When selecting activities for health, people can be advised that strength sports are not more likely to cause injury than endurance sports.
A bodybuilding style of resistance-training seems to lead to a lower injury rate than other types of resistance-training. When selecting activities for health, this method of training may lead to a superior risk-reward ratio than strongman, powerlifting, or Olympic weightlifting styles of training.
Whether it is worth considering deliberately using bodybuilding-style training in athletic programs in order to reduce training injury rates seems premature until research clarifies its effect on performance and competition injury risk.