Disclaimer: this post is not meant to replace medical advice. Before starting any workout regimen it is important to get clearance from your doctor to avoid adverse events.
As someone who is a physical therapist who also does CrossFit I get questioned a lot about the safety of CrossFit. I’ve even had people ask me “how can you be a physical therapist and still do CrossFit?” There are a lot of people who believe it causes injuries, have experienced an injury themself in CrossFit, or know someone who has sustained an injury.
There are not a lot of peer reviewed journal articles out there on this topic since this sport is relatively new. I have summed up what I’ve come across in the information to follow.
Injury Incidence and Prevalence in CrossFit
In a study by Costa et al (2019), they surveyed CrossFitters at multiple CrossFit-affiliated sites using a questionnaire. These authors defined injury as an incident that resulted in at least 1 week of rest from physical activity, something that the individual sought medical attention for, or at least 2 weeks duration of modification for intensity, duration, or modality for workouts. The incidence of injuries sustained was 3.24 injuries per 1,000 hours of participation and the prevalence was about 36%. The results found that the most common injuries sustained included shoulder and low back injuries. It’s important to note that the amount of injuries and type of injury are very similar to injuries sustained in the sports of olympic weightlifting, gymnastics, and powerlifting all of which are foundational movements of CrossFit. This article also notes that injuries occur at a higher rate in individuals who may be competitive with the sport of CrossFit. Majority of injuries reported in this study were mild to moderate in severity. This means they healed relatively quickly and was not long standing. Muscle strains would go under the category of a mild injury in most cases which I find to be a very common injury in CrossFitters caused by overtraining or overloading- this is based solely on my experience.
Costa, et al. 2019. CrossFit: Injury prevalence and main risk factors. Clinics;74
Physiological Changes in CrossFit
In terms of physiological function with CrossFit, there is an interesting study by Timon et al (2019) that goes into detail about biomarkers with two different types of CrossFit workouts. The first workout was in the style of “as many reps as possible” (AMRAP) during an allotted time frame, where your score is the amount of reps you did. The second style was a “rounds for time” (RFT) workout where you do the workout as fast as you can, and your score is the time it took to complete the workout. They looked at physical performance and biomarkers up to 48 hours following the workouts. The plank was used immediately following the workout and again at 24 hours and 48 hours following the workout to measure physical performance of trunk/core stabilizing muscles. Biomarkers were measured via blood draw to assess inflammatory and metabolic stress. It was found that individuals had a decrease in physical performance and an increase in biomarkers following the workout and up to 48 hours post-workout. These measures returned to baseline after 48 hours. When comparing the two types of workouts the RFT style elicited greater stress on the body than did the AMRAP style. It is important to note that none of these participants had reached a level of pathology from these workouts. This means that depending on the workout style, the amount an individual participates in CrossFit during the week, and the movements during a CrossFit workout there may be an impact on the potential injuries sustained. If your core is fatigued from the day prior’s workout and you are doing heavy deadlifts that day, you are at a higher risk of injury compared to someone who had rested the day prior. It is important in these scenarios to remember the importance of recovery and the potential need for modifying if you’ve had a week of intense workouts.
Timon, et al. 2019. 48-hour recovery of biochemical parameters and physical performance after two modalities of CrossFit workouts. Biol Sport;36(3)
Another interesting study was performed by Poderoso et al (2019) where they looked at hormonal changes in CrossFit participants over a period of 120 training sessions with data taken at baseline, month two, month four, and month six. They found a statistically significant increase of testosterone in male participants with no significant change in female athletes following a CrossFit workout. Cortisol was significantly lower in both males and females at month six compared to baseline and month two. This study is interesting as long duration CrossFit participation may lead to higher levels of testosterone in men and decreased cortisol in men and women. Cortisol is a hormone naturally produced in the body that helps regulate sugar, reduce inflammation, regulate salt:water balance, and regulate metabolism amongst other important functions. However, this hormone increases in individuals with high stress levels and has also been seen to be elevated in obese individuals.
Poderoso, et al. 2019. Gender diffferences in chronic hormonal and immunological responses to CrossFit. Int J Environ Res Public Health;16
Injuries in other Sports
Arnold and Moody (2018) looked at injuries sustained in runners. They note that the one-year injury rate was 27% in novice runners, 32% in long distance runners, and 52% in marathon runners. Unlike CrossFit the most common injuries were tendinopathies especially in the knee and ankle.
Arnold & Moody. 2018. Common running injuries: Evaluation and management. American Family Physician;97(8)
Even golf has a significant number of injuries every year. Parziale and Mallon (2006) discuss injury rates in golfers. They discuss a study of 167 golfers of which 57% had sustained some sort of injury. Of these injuries, men were most likely to sustain low back injuries whereas females had an injury of the upper extremity in both amateur and professional golfers.
Parziale & Moody. 2006. Golf injuries and rehabilitation. Phys Med Rehabil Clin N Am;17
A very interesting systematic review by Cramer et al (2018) discusses injuries that are sustained during yoga. They found that incidence of an injury during a yoga class was 22.7%. The prevalence of injury over one year was 4.6% and over a lifetime was 21.3% of the yoga practitioners, however serious injuries only occurred in 1.9% of individuals. The most common injuries sustained were muscle strains or ligament sprains.
Cramer & et al. 2018. Injuries and other adverse events associated with yoga practice: A systematic review of epidemological studies. J Sci Med Sport;21(2)
Benefits of CrossFit
Lastly, in an article by Briseboise et al (2018) they looked at physiological and fitness adaptions in previously inactive adult individuals following an eight week high intensity functional training (HIFT) CrossFit regimen. These individuals performed the HIFT program three times per week for one hour, including a warm up, workout, and cool down. Physiological results found included an improved VO2max and decreased resting diastolic blood pressure. These individuals had decreased body fat as well as increased lean body mass. Even though leg press and bench press were not performed during the entirety of the HIFT program, there was still an increase in both bench press and leg press 5 rep max when compared to pre-regimen testing. They also found an improvement in upper body muscular endurance through the YMCA bench press test. The researchers also tracked injuries and found only very acute injuries were sustained. This study also notes that the general frequency of injuries sustained during CrossFit style workouts are similar to that of powerlifting and olympic weightlifting but less than that of any contact sport.
Brisebois, et al. 2018. Physiological and fitness adaptions after eeight weeks of high-intensity functional training in physically inactive adults. Sports;6
CrossFit has become my outlet for stress and has fulfilled a hole I’ve had since ending my competitive cheerleading career. I can honestly say I have never been healthier and the community I have been welcome into has become my biggest support system. Yes I have sustained injuries during my time participating in CrossFit but these injuries were from overtraining and I have always recovered in under a week. I will end this by saying CrossFit may not be appropriate for every single person, but it is highly modifiable which allows for almost anyone to participate. Not everyone has to lift heavy, go full depth in a squat, perform impact activities, or do the high skilled movements. There are many options for modifications that will keep you safe and still allow for a good workout. It also has a lot to do with the coaches. If you go to a gym with good coaches, they will ensure you are performing movements with good form and at a weight that is appropriate for you. There are coaches out there that simply push for you to do heavy weights that you have no business doing or perform movements during a workout that you haven’t yet perfected. So if you are interested in CrossFitting then you need to do your research and find gyms that have high rated coaches. I also want to state that all forms of activity have their own risk of injury. CrossFit has been in a negative spotlight however there is no research out there that I came across that shows CrossFit having higher injury rates than any other sport.