Athletic Training and Sports Health Care

Sports Medicine Digest 

A Physiotherapy Perspective of CrossFit: Guiding You Safely

Jo Ann Kaye, MSc; Jenny Alexanders, PhD, MSc; Lois Smith, MSc

Abstract

Clinical Question: To examine current literature on the effects of CrossFit training (CrossFit, Inc.) on injury rates, provide physiotherapists with an appropriate evidence platform, and generate further interest in this field.

Summary: CrossFit is a constantly varied, high-intensity functional endurance and strength program that has seen a considerable growth in popularity.1 With more than 13,000 licensed CrossFit affiliates worldwide, physiotherapists should have a general knowledge of CrossFit exercise routines due to an increase in patient engagement in such activities. Research and scholarly activity focusing on the incidence and prevalence of both acute traumatic and chronic overuse injuries in CrossFit continues to rise.3 Large scale epidemiological and prospective studies are gaining momentum from the orthopedic, sports science, and coaching sectors into associations between the physiological characteristics of CrossFit and injury.3 Despite these studies occupying valuable journal space, the insightful findings may not be reaching the appropriate physiotherapy audience. Considering physiotherapists play a key role in managing the sports performer, having a sound understanding of CrossFit is of paramount importance in positively shaping the athlete's rehabilitation outcomes and expectations.4

Main Results: CrossFit is a conditioning program that blends multiple synchronistic exercises ranging from rowing, running, and gymnastics to Olympic lifting and power lifting. These exercises are structured into high-intensity workouts that are performed in a rapid and repetitive manner with limited recovery time.5 CrossFit, whose slogan is “forging elite fitness,” aims to prepare individuals for the unknown by mastering the following 10 skills: cardiovascular and respiratory endurance, stamina, strength, flexibility, power, speed, coordination, agility, balance, and accuracy.6 CrossFit programs are based on eccentric exercises involving open chain movements and eccentric lengthening of loaded muscle-tendon units to generate increased force while using fewer motor units.7 Performing such exercises improperly can cause indirect musculoskeletal injuries.7

Weisenthal et al5 identified that 20% of injuries among CrossFit athletes were attributable to Cross-Fit itself, with no significant data suggesting that those who trained more were more susceptible to injuries. Participants reported injuring their shoulders, knees, and lower back most frequently, which was due to gymnastic and power lifting motions.5 These findings are consistent with injury rates in gymnasts and power lifters, who both report similar shoulder pathologies.2 Similarly, the study by Chachula et al7 identified 44% of CrossFit athletes (aged 24 to 54 years) experienced joint-related injuries during Cross-Fit training.Those who presented with no previous or ongoing injuries demonstrated an injury prevalence of 22% (4 of 18) that was not dependent on age or experience. The study by Chachula et al7 was limited due to different population sizes, coaching experience, and risk of potential recall bias.

Shoulder injuries are related to fatigue. Unfamiliarity, excessive loads, speed and repetition, and safety issues are particularly prevalent among CrossFit athletes. Muscular fatigue is a common cause of shoulder injury due to the congruity of the glenohumeral joint requiring correct muscular activation and stabilization.1 Repetitive overhead movements require a significant range of shoulder movement and stability, and athletes should be aware of the potential risks surrounding this. Athletes should strive to reduce risks by ensuring that appropriate form is consistently demonstrated. Correspondingly the musculoskeletal demands of shoulder are similar to weightlifting.8 Subsequent injury prevalence literature reported 76% of weightlifters sustained musculoskeletal trauma, with the majority of them being associated with the shoulder complex.9 It is therefore of critical importance that physiotherapists have sufficient understanding in relation to the physiological characteristics and potential mechanisms of injury of patients who partake in CrossFit. In addition, physiotherapists should consider reviewing past injury patterns before recommending a safe return to the CrossFit environment to minimize reinjury.10

Empirical evidence has revealed that CrossFit training can be…

Clinical Question: To examine current literature on the effects of CrossFit training (CrossFit, Inc.) on injury rates, provide physiotherapists with an appropriate evidence platform, and generate further interest in this field.

Summary: CrossFit is a constantly varied, high-intensity functional endurance and strength program that has seen a considerable growth in popularity.1 With more than 13,000 licensed CrossFit affiliates worldwide, physiotherapists should have a general knowledge of CrossFit exercise routines due to an increase in patient engagement in such activities. Research and scholarly activity focusing on the incidence and prevalence of both acute traumatic and chronic overuse injuries in CrossFit continues to rise.3 Large scale epidemiological and prospective studies are gaining momentum from the orthopedic, sports science, and coaching sectors into associations between the physiological characteristics of CrossFit and injury.3 Despite these studies occupying valuable journal space, the insightful findings may not be reaching the appropriate physiotherapy audience. Considering physiotherapists play a key role in managing the sports performer, having a sound understanding of CrossFit is of paramount importance in positively shaping the athlete's rehabilitation outcomes and expectations.4

Main Results: CrossFit is a conditioning program that blends multiple synchronistic exercises ranging from rowing, running, and gymnastics to Olympic lifting and power lifting. These exercises are structured into high-intensity workouts that are performed in a rapid and repetitive manner with limited recovery time.5 CrossFit, whose slogan is “forging elite fitness,” aims to prepare individuals for the unknown by mastering the following 10 skills: cardiovascular and respiratory endurance, stamina, strength, flexibility, power, speed, coordination, agility, balance, and accuracy.6 CrossFit programs are based on eccentric exercises involving open chain movements and eccentric lengthening of loaded muscle-tendon units to generate increased force while using fewer motor units.7 Performing such exercises improperly can cause indirect musculoskeletal injuries.7

Weisenthal et al5 identified that 20% of injuries among CrossFit athletes were attributable to Cross-Fit itself, with no significant data suggesting that those who trained more were more susceptible to injuries. Participants reported injuring their shoulders, knees, and lower back most frequently, which was due to gymnastic and power lifting motions.5 These findings are consistent with injury rates in gymnasts and power lifters, who both report similar shoulder pathologies.2 Similarly, the study by Chachula et al7 identified 44% of CrossFit athletes (aged 24 to 54 years) experienced joint-related injuries during Cross-Fit training.Those who presented with no previous or ongoing injuries demonstrated an injury prevalence of 22% (4 of 18) that was not dependent on age or experience. The study by Chachula et al7 was limited due to different population sizes, coaching experience, and risk of potential recall bias.

Shoulder injuries are related to fatigue. Unfamiliarity, excessive loads, speed and repetition, and safety issues are particularly prevalent among CrossFit athletes. Muscular fatigue is a common cause of shoulder injury due to the congruity of the glenohumeral joint requiring correct muscular activation and stabilization.1 Repetitive overhead movements require a significant range of shoulder movement and stability, and athletes should be aware of the potential risks surrounding this. Athletes should strive to reduce risks by ensuring that appropriate form is consistently demonstrated. Correspondingly the musculoskeletal demands of shoulder are similar to weightlifting.8 Subsequent injury prevalence literature reported 76% of weightlifters sustained musculoskeletal trauma, with the majority of them being associated with the shoulder complex.9 It is therefore of critical importance that physiotherapists have sufficient understanding in relation to the physiological characteristics and potential mechanisms of injury of patients who partake in CrossFit. In addition, physiotherapists should consider reviewing past injury patterns before recommending a safe return to the CrossFit environment to minimize reinjury.10

Empirical evidence has revealed that CrossFit training can be particularly addictive.11 CrossFit training may lead to fatigue and weakness, with overtraining increasing the risk of harm. This addictive nature can cause individuals to overtrain, especially in the early periods of starting this type of training. Many individuals may not be conditioned for the increase in plyometric exercises and training dosages.11 Incorrect training and education may also hinder the safe pursuit of CrossFit programming. Each CrossFit gym coach is required to have a minimum Crossfit Level 1 qualification from a CrossFit-approved course, and can choose to complete several additional courses to further knowledge in specific areas, such as CrossFit Kids, CrossFit Gymnastics, and Crossfit Weightlifting.12 Even with these specific courses, there is evidence of a wide variation in the quality of CrossFit gyms based on the understanding, knowledge, and experience of coaches.5

Nonetheless, studies have shown there are no differences in fundamental movement patterns between Cross-Fit and other traditional programs such as weightlifting.1 Crossfit leads to aerobic gains, anaerobic gains, and injury rates similar to weightlifting, powerlifting, triathlon training, and gymnastics.13 Therefore, an important factor in improving performance and prevention of injuries is to swiftly recognize and correct defects in mobility, stability, and symmetry.

Feito et al14 provided a multiyear assessment of injuries among individuals who engage in CrossFit training, which indicated that it was a safe training modality. However, individuals within the first year of training and those who participate more than 3 days per week are at a greater risk of injury due the to new intensity, duration, and type of exercise.Therefore, physiotherapists are in an ideal position to safely guide individuals through CrossFit training by highlighting the potential risks and outcomes and how to train and progress through the skills safely and efficiently. Physiotherapists would benefit from having an in-depth understanding of the different components that Cross-Fit offers, which will reduce altered motor programs throughout the kinetic chain if identified initially.14

Meyer et al's systematic review2 acknowledges individuals who engage in CrossFit perform better and have higher gains in aerobic capacity and anaerobic cover. CrossFit gives athletes the freedom to train and develop different skills without direct supervision, which is where the knowledge and expertise from physiotherapists could provide safe and effective recommendations to prevent injury.5

Conclusions: Every form of physical activity holds potential risk of injury, and rates of CrossFit training injuries are consistent with rates in other fitness routines.2 Individuals want to strive for optimum success within CrossFit, and they want to achieve this in a safe and effective manner. Likewise, physiotherapists want to help people engage in fitness activities while understanding the health implications and safety of those activities to continue to improve their strength, stamina, endurance, and mobility within a safe environment.14

Physiotherapists should have an awareness of CrossFit training to accurately treat the various patterns of injuries incurred by athletes. Comparable injuries can be found in other recreational athletes such as runners, Olympic lifters, gymnasts, and power lifters.5 Despite the variety and intense nature of CrossFit, injury rates do not vary from other similar intense activities, and there is no correlation between demographic or training data with the presence of injury. With safe incremental increases in intensity, accurate coaching, slow progression, and good technique, CrossFit can be a beneficial form of exercise for healthy adults looking for a varied routine. There is no consistent evidence to suggest that CrossFit is injuring athletes more than other comparable exercise routines.

References

  1. Tafuri S, Notarnicola A, Monno A, Ferretti F, Moretti B. CrossFit athletes exhibit high symmetry of fundamental movement patterns: a cross-sectional study. Muscles Ligaments Tendons J. 2016;6(1):157–160. doi:10.32098/mltj.01.2016.19 [CrossRef]
  2. Meyer J, Morrison J, Zuniga J. The benefits and risks of CrossFit: a systematic review. Workplace Health Saf. 2017;65(12):612–618. doi:10.1177/2165079916685568 [CrossRef]
  3. Reichel T, Mitnacht M, Fenwick A, Meffert R, Hoos O, Fehske K. Incidence and characteristics of acute and overuse injuries in elite powerlifters. Cogent Med. 2019;6(1):1588192. doi:10.1080/2331205X.2019.1588192 [CrossRef]
  4. Quartey J, Afidemenyo S, Kwakve SK, Quartey J, Ghana KA, Kwakve SK. Athletes expectations about physiotherapy in sports injury rehabilitation in greater Accra region. Hong Kong Physiother J. 2019;39(2):1–14. doi:10.1142/S1013702519500094 [CrossRef]
  5. Weisenthal BM, Beck CA, Maloney MD, DeHaven K, Giordano BD. Injury rates and patterns among CrossFit athletes. Orthopedic J Sports Med. 2014;2(4).
  6. Glasman G. Foundations: The CrossFit Journal. 2002. Accessed January 18, 2018. https://library.crossfit.com/free/pdf/Foundations.pdf
  7. Chachula LA, Cameron KL, Svoboda SJ. Association of proper injury with the report of new injuries sustained during CrossFit training. Athletic Training & Sports Health Care. 2016;8(1):28–34. doi:10.3928/19425864-20151119-02 [CrossRef]
  8. Summitt RJ, Cotton RA, Kays AC, Slaven E. Shoulder injuries in Individuals who participate in CrossFit Training. Phys Ther. 2016;8(6):514–520.
  9. Everhart JS, Kirven JC, France T, Hidden K, Wasileff W. Rates and treatment of CrossFit-related injuries at a single hospital system. Curr Orthop Pract. 2019;30(4):347–352. doi:10.1097/BCO.0000000000000766 [CrossRef]
  10. Oh RC. Coming out of the CrossFit closet. Journal of the Uniformed Services Academy of Family Physicians. 2013;7(1):31–33.
  11. Lichtenstein MB, Jensen TT. Exercise addiction in CrossFit: prevalence and psychometric properties of the exercise addiction inventory. Addict Behav Rep. 2016;3:33–37. doi:10.1016/j.abrep.2016.02.002 [CrossRef]
  12. CrossFit Training Courses. 2018. Accessed January 18, 2018. https://training.crossfit.com/specialty
  13. Klimek C, Ashbeck C, Brook AJ, Durall C. Are injuries more common with cross-fit training than other forms of exercise?J Sport Rehabil. 2018;27(3):295–299. doi:10.1123/jsr.2016-0040 [CrossRef]
  14. Feito Y, Burrows E K, Tabb L P, Matson A. A 4-year analysis of the incidence of injuries among CrossFit-trained participants. Orthop J Sports Med. 2018;6(10):2325967118803100. doi:10.1177/2325967118803100 [CrossRef]
Authors

From the School of Health and Social Care, Teeside University, Middlesbrough, United Kingdom (JK, JA); and the Department of Sport, Health, and Exercise Science, School of Life Science, University of Hull, Yorkshire, United Kingdom (LS).

The authors have no financial or proprietary interest in the materials presented herein.

Correspondence: Jo Ann Kaye, MSc, School of Health and Social Care, Centuria Building, Teesside University, Middlesbrough TS1 3BX, United Kingdom. Email: K0036121@live.tees.ac.uk

10.3928/19425864-20200305-01

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