- HYROX is a relatively new fitness competition, created in 2017, that combines 8 km of running with performance at eight exercise stations.
- In this international survey of more than 400 HYROX competitors, half reported sustaining an injury the previous year during training; pain related to tendons in the lower extremities, with gradual onset, was the most common injury type.
- Many of these injuries were consistent with overuse, suggesting that competitors should adjust their training regimens to avoid excessive strain.
Half of participants in a new, increasingly popular fitness competition called HYROX said they had sustained an injury during training for it during the previous year, an international survey found.
Among 418 HYROX athletes from 30 countries and territories, 49.8% reported at least one injury they believed was related to their training in the past 12 months, according to Michael Zyskowski, PD Dr.med, of the Technical University of Munich, and colleagues.
The survey, administered earlier this year, also asked how much time respondents had spent in training, which added up to 177,000 hours. With 293 injuries reported in total, that worked out to a rate of 1.65 per 1,000 hours of training, the researchers reported in a manuscript posted to the medRxiv preprint server (which therefore has not yet been peer reviewed).
While that may seem high, the sport is relatively intense and studies of other competitive activities show similar or even higher rates. A recent meta-analysis focusing on CrossFit, for example, found a rate of 3.2 per 1,000 hours for musculoskeletal injuries. In another study, professional soccer players incurred 8.1 injuries per 1,000 hours.
HYROX was introduced in Hamburg, Germany, in 2017 and has since expanded around the world. It is conducted indoors, primarily in big-city exhibition halls, and combines 8 km of running with performance at eight exercise stations. The latter involve a SkiErg machine, broad jumps, rowing, and carrying, pulling, and pushing heavy weights. Some 1.5 million individuals are estimated to participate this year, with more than 100 races scheduled, including 17 in the U.S. over the next 12 months.
One reason for its popularity is that, unlike most other fitness competitions, it is completely standardized — it’s exactly the same at every venue, so that performance in different events is easily compared. Since it’s indoors, weather is not a factor. An individual can expect to spend around 90 minutes completing the course during a competition, according to the HYROX website.
Although it’s arguably the world’s fastest-growing fitness sport, only one previous study has examined its injury epidemiology, Zyskowski and colleagues observed — an ad hoc survey of 80 HYROX participants, with only two sentences in the published report addressing injuries (although it, too, found a rate close to 50%).
Of the 418 athletes included in the new survey, 274 were from Germany; 31 were from the U.S., which had the next most respondents. Mean age was 37, and 55% were men. Most reported having previously participated in other fitness sports.
Among 197 of those with injuries who also provided data on their severity, 13% said they had to stop training for 4 weeks or more, and 8% reported never returning to their previous performance ability.
Relatively few injuries occurred during actual HYROX competitions — just 9%. Most were attributed either to general endurance (30%) or strength training (10%) or to activity meant to prepare specifically for a competition (28%). Running took the biggest toll, accounting for 28% of injuries; the next most common injury-producing activity was the “sandbag lunge” at 12%.
The lower body was primarily affected. Knee injuries were 21% of the total, followed by spine/back problems (15%), the hip-groin area (13%), feet (8%), and ankle (7%). Only 10% of injuries affected shoulders or arms. Moreover, for 42% of injuries, respondents believed they involved the tendons; another 20% said they were muscular and 13% blamed ligaments. Well over half came on gradually over time.
Athletes’ sex and body types didn’t seem to affect injury rates, as no association was seen for such factors as body mass index (BMI). In fact, the only factor that appeared to predict injury was higher training frequency, which the researchers divided into five categories ranging from less than once weekly to daily; each step up was associated with 61% greater odds for injury (P=0.001).
Overall, Zyskowski and colleagues said the pattern was strongly suggestive of overuse injury. While they cautioned that the study design precludes assertions about causality — prospective studies focusing more closely on training regimens are needed, they wrote — their results still support recommendations for athletes and their support people.
“The predominance of gradual onset, lower-extremity and tendon-related complaints suggests that athletes, coaches and clinicians should be alert to overuse problems, particularly around running and lower-limb loading, and that overall training load — including weekly frequency — deserves attention,” they wrote.
HYROX doesn’t give much information itself regarding safety during training, advising only that athletes should “familiarize” themselves with the sport “so that you train the exercises in the right manner and avoid bad movements and potential injuries.”
The study came with several limitations: respondents were recruited in several ways (through gyms and coaches, social media, and printed materials) but may not be entirely representative of the HYROX community, and data were all self-reported and therefore subject to multiple potential biases and errors. That most respondents were from Germany may also limit generalizability to other regions. The survey may have been underpowered for some subgroup analyses, such as by BMI category.
