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Crossfit Medicine

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Related Terms

  • High Intensity Functional Training (HIFT)
  • High Intensity Power Training (HIPT)
  • Extreme Conditioning Program (ECP)
  • High Intensity Circuit Training
  • CrossFit

Background

  • This page focuses on CrossFit Medicine

History

  • The CrossFit program was developed in 2000.
    • The CrossFit Games, a competition among CrossFit athletes, first started in 2007.[1]

Epidemiology

  • As of 2022, greater than 5 million people globally participate in CrossFit. [1]
    • Of CrossFit athletes, 60% are assigned female at birth.
    • Age breakdown: under 18 (18%), 18-24 (6%), 25-34 (40%), 35-44 (20%), 45-54 (8%), over 55 (7%)
  • Incidence
    • Rate of injuries for CrossFit appears to be similar to that of weightlifting and powerlifting.
    • In a systematic literature review involving 12,079 CrossFit participants across 25 studies, the mean prevalence of musculoskeletal injuries was 35.3%, with an incidence rate between 0.2 and 18.9 per 1000 hours of training.[2]
    • From the studies reviewed, the most common injuries include the shoulder (26%), spine (24%), and knee (18%), and on average 8.7% of the injuries required surgery.[2]

Introduction

  • CrossFit is a company and the trademark name of a strength and conditioning program that involves varied, high intensity functional movement exercises.
    • The fitness regimen incorporates movements derived from powerlifting, gymnastics, calisthenics, plyometrics, and high intensity interval training.
    • Equipment includes barbells, dumbbells, kettlebells, pull-up bars, plyometric boxes, and rowing machines.

Level of Evidence

  • Studies on Crossfit are Limited
    • This includes evaluation of musculoskeletal injury, health aspects, psycho-physiological parameters, and social factors
    • In a 2018 systematic review, only 2 of 31 articles had a high level of evidence and low risk of bias[3]
    • Another 2020 systematic review examining prevalence of injuries showed 11 of 12 studies that met inclusion criteria displayed poor methodological quality.[4]
    • Thus, this page summarizes the best available literature to date regarding CrossFit injuries

Terminology: Pathology

  • Tendinopathy: condition of the tendon causing pain and/or swelling
  • Joint injury: injury of tissues within the joint, including ligaments, tendons, cartilage, and synovial fluid
  • Muscle Strain: stretching or tearing of muscle fibers[5]
    • Grade I strain: limited number of fibers affected
    • Grade II strain: nearly half of fibers torn
    • Grade III strain: complete rupture of the muscle
  • Fracture: partial or complete break in the bone, uncommon in Crossfit
    • Closed: skin remains intact, also termed simple
    • Open: bone protrudes through the skin, also termed compound
    • Non-displaced: bone breaks but remains in relative alignment
    • Displaced: bone breaks moves out of alignment
  • Dislocation: separation of two bones at a joint, less common in CrossFit
  • Rhabdomyolysis: breakdown of muscle tissue and release of intracellular muscle components into the circulation

Terminology: CrossFit Exercises

  • Deadlift: lifting a loaded bar/barbell off the ground to the level of the hips before lowering it to the ground.
  • Kettle Bell: a common CrossFit weight. Measured in 16lb increments called Pood’s
  • Kipping: a rocking motion to help use momentum to complete a pull-up
  • Snatch: lifting a loaded bar from the ground in a squat position, and flinging it above the head and standing upright in a fluid motion.
  • Clean and jerk: Olympic Lift. Lifting movement of moving weight to rack position (clean) and then moving weight above head (jerk).
  • Bench press: bodybuilding and weightlifting exercise in which a lifter lies on a bench with the feet on the floor and raises a weight with both arms.
  • Push press: while holding barbell in rack position, lift weight above head.
  • Power clean: Olympic lift. Barbell starts on the ground and end in the rack position. See definition of clean.
  • Squat: feet shoulder width apart with feet angled slightly outward. Keeping upper body rigid, bend at the knees lowering upper body in straight line.
  • Overhead press: The overhead press is an upper-body weight training exercise in which the trainee presses a weight overhead while seated or standing.
  • Muscle-up: A combination of pull-up and ring dip
  • Pistol: One-legged squat; sometimes termed a pistol squat
  • Power Clean: Olympic lift. Barbell starts on the ground and end in the rack position. See definition of clean.
  • Power Snatch: Olympic Lift. Barbell starts on the ground and ends up overhead. See definition of squat.
  • Push Jerk: while holding barbell in rack position, slightly squat down and lift weight above head.
  • Push Press: while holding barbell in rack position, lift weight above head.
  • Rack Position: Bar resting on you collar bone and anterior deltoids support by hands.
  • Renegade Rows: variation of push up. While in push up position holding dumbbells, lift each dumbbell alternately with each arm
  • Squat: feet shoulder width apart with feet angled slightly outward. Keeping upper body rigid, bend at the knees lowering upper body in straight line.
  • Squat Snatch: Olympic lift. Barbell starts on the ground and ends up in the overhead squat position. See definition of squat.
  • Stabilize the Midline: Controlling the muscles around the spine to make it stable and strong during exercise
  • Sumo Deadlift High Pull: In a wide stance over a barbell, explosively pull the barbell up from the ground to shoulder height.
  • Tabata: A protocol of 20 seconds of exercise followed by 10 seconds of rest. Named after Dr. Tabata.
  • Thrusters: Hold barbell in rack position, drop down in squat position with barbell in rack position, return to standing position in exploding motion, pushing the barbell over you head.
  • Unbroken (UB): Perform all workouts in a row or start over at the beginning.
  • Wall Balls: Using a medicine ball, drop into a front squat position and stand up using the momentum to push the ball to hit a target on the wall.

Terminology: Equipment

  • Medicine Ball
  • Bike
  • Track
  • Ergometer
  • Rings
  • Parallel bars
  • Plyometric boxes
  • Jump rope
  • Barbell
  • Dumbbell
  • Plates
  • Weighted Vest

Abbreviations

  • WOD: Workout of the day
  • BW: body weight
  • C2: Concept 2 rowing machine
  • CFT: CrossFit Total. The combined weight of your max squat, press, deadlift.
  • CTB/C2B: Chest to bar pull up. Pull body up so that chest crosses the bar.
  • DNF: Did not finish
  • DNS: Did not start
  • DUB: Double under. Refers to clearing the jump rope twice in a single jump.
  • HSPU: Handstand Push Up
  • PB: Personal Best
  • PR: Personal Record
  • ROM: Range of motion

Affiliated Bodies


Risk Factors

  • While studies are limited, risk factors for injury include:[2][6]
    • Previous injuries
    • Lack of coach supervision
    • Male sex
    • Participation in competitions
    • Greater body mass index
    • Frequency of training (some studies show conflicting evidence)
    • Older age (some studies show no significant association)
  • Risk of injury is also associated with type of CrossFit movement
    • Squats and deadlifts responsible for a large portion of injuries, as shown in the figure below.[6]

Pathophysiology

Risk of injury

  • Risk of injury in CrossFit is linked to explosive movements and heavy loading[2]
    • Result in greater strain on joints, range of motion demands, and exertional fatigue
  • Additionally, high intensity with maximal repetitions and minimal rest intervals
    • Increases risk of overuse injury, overreaching, overtraining, and unsafe movement execution.[7]
  • Causes of injury are multifactorial, although overarching mechanism is suspected to be related to the summation of stresses that exceeds the mechanical capacity of the biological tissue involved.[3] Such injuries commonly occur when athletes train beyond their capacity.
  • Injury type is associated with particular CrossFit movement types[8]
    • Shoulder injuries are most common with gymnastics movements
    • Lower back injuries were most common with power lifting movements.

Shoulder

  • Movements like pull-ups, bar dips, and rope climb put large demand on shoulder stability and range of motion.[2]
  • Movements during bench press and snatch put the shoulder in extreme flexion and abduction.[2]
  • When the shoulder is in hyperflexion, internal rotation, and abduction
    • Forces are distributed to the joint and surrounding tissue, increasing the risk of injury.[6]

Spine

  • Movements like squats, deadlifts, and tire flips require spinal alignment through extension of the lower back.
  • Improper technique, especially in the setting of fatigue from heavy weight and high repetitions, increases the risk of spondylosis back injuries.[9]
  • Quadriceps fatigue may alter posture and spinal alignment during a lift, and the stooped position
    • I.e. flexed as opposed to extended lower back places greater stress on the thoracic and lumbar spine
    • Increasing the risk of spinal injury.[6][10]

Knee

  • Powerlifting movements put a heavy load on stabilizing soft tissues in the knee, potentially increasing risk of injury.
  • Increased depth of squat (40-45° vs 80-100° knee flexion) was once suspected to contribute to degenerative changes
    • Thought to be due to increased compressive stress and range of motion on the tendofemoral complex
    • A 2013 literature review demonstrated no such correlation.[11]

Tendon

  • Acute increases in tendon thickness have been noted following CrossFit sessions.
    • A post-exercise ultrasound evaluation showed significant increase in patellar and Achilles tendon thickness (n=34)
    • Likely associated with concentric and eccentric muscle movements.[12]
    • The significance of these morphological changes on risk of injury requires further investigation.

Muscle

  • Rhabdomyolysis[13]
    • Intense exercise may result in rhabdomyolysis, the breakdown of muscle tissue
    • Symptoms include muscle pain, weakness, nausea/vomiting, and confusion.
  • While rare, cases of rhabdomyolysis in the setting of CrossFit training have been reported
    • One such includes in 35 year old woman who was hospitalized for edema, weakness, and reduced range of motion of her upper extremities following 3 days of intense exercise through kayaking and pull-ups in CrossFit.[14]

Prevention

  • Goal is to decrease risk of injury due to[7]
    • Overuse or improper technique
    • Appropriate supervision
    • Progressive increases to load and intensity

Technique

  • Proper technique and progressive training loads[11]
    • Can strengthen the lower extremity and protect against injuries of the knee.
  • Maintaining spinal alignment throughout powerlifting movements like squats and deadlifts[6]
    • Prevent back injury.
  • Supervision by a trainer can lower the risk of improper technique and is associated with lower injury risk.

Stretching

  • Stretching for injury prevention has long been debated.
  • In a cross-sectional study, stretching was associated with increased injury[6]
    • However, it is difficult to draw conclusions as the type of stretching (static vs dynamic) was not elicited.
  • Commonly agreed that sports with high-intensity stretch-shortening cycles require more compliant muscle tendon units[15]
    • Athletes should benefit from dynamic stretching to increase muscle compliance
    • Further studies are needed to determine a recommendation

Frequency

  • The literature characterizing relationship between frequency of training and injury is mixed.
    • Some studies report greater prevalence of injury with infrequent weekly training sessions
    • Others report increased prevalence of injury with increased frequency of training.
  • The relation between experience level and injury is similarly mixed.[6]
  • Frequency of training and experience level are likely confounded by factors like improper technique and training beyond capacity.[6]
    • Improper technique may stem from the inexperience of athletes who practice CrossFit infrequently.
    • Improper technique may also stem from experienced athletes who practice CrossFit frequently
    • But compromise their form or ability to recover by training beyond capacity.

Stabilization exercises

  • Ankle stabilization exercise[16]
    • Performed before CrossFit has shown promise for patients with chronic ankle insufficiency.
    • In a randomized control trial, ankle-dorsiflexion range of motion had greater improvement for those participating in CrossFit with stabilization exercises compared to CrossFit alone.

Nutrition recommendation

  • No evidence-based nutritional recommendation currently exists specifically for CrossFit
  • From a 2021 systematic review of CrossFit and dietary supplementation[17]
    • Further studies are needed to identify optimal nutritional strategies for performance and recovery.

Comorbidity Considerations

Obstetrics

  • Evidence is limited
    • CrossFit among nulliparous women was shown to have no significant beneficial or deleterious effect on pelvic floor strength.[18]
    • At this time, there is no evidence to suggest CrossFit is unsafe for pregnant women with uncomplicated pregnancy

Cardiovascular

  • No studies to date have measured the impact of CrossFit on resting blood pressure and heart rate.[3]

Pulmonary

  • CrossFit is an aerobically intensive workout
    • Thus care must be taken for those with respiratory diseases
    • Patients with asthma should be managed with an appropriate medical regimen for asthma control and exacerbation.

Psychiatric

  • An 8-week randomized control trial studied mental health in adolescents participating in CrossFit[19]
    • No improvement in mental health was seen overall
    • However, significant improvement in mental health was seen in a subgroup identified as “at risk” of psychological distress.
  • Exercise addiction[20]
    • Tendency to continue exercise despite injury, feelings of guilt when unable to exercise, development of obsession with exercise.
    • Initial surveys have shown exercise addiction is prevalent in CrossFit, with young males at highest risk.

MSK

  • Previous injuries are some of the most significant risk factors for subsequent injuries
    • Caution should be taken for those with persistent musculoskeletal injuries.
    • Appropriate rest and gradual return to exercise should be considered.[2]

Complications

  • Musculoskeletal injuries are the most common adverse consequences from CrossFit.
  • Complications from extreme exertion include rhabdomyolysis
  • Urinary incontinence due to effects on pelvic pressure
    • A systematic review demonstrated no significant difference in prevalence of incontinence among women participating in CrossFit compared to women participating in other sports.[21]
  • Case reports described in the literature
    • 1 case of a tear of the latissimus dorsi myotendinous junction during a muscle-up [22]
    • 1 case of a retinal detachment during a weighted pull-up [23]
    • 3 cases of cervical carotid dissection have been associated with CrossFit, however direct causality was not shown [24]
    • 1 case of an intracranial hemorrhage in a young man with no trauma or stroke risk factors [25]

See Also


References

  1. 1.0 1.1 81 CrossFit Statistics You Should Know. LIVESTRONG.COM. Accessed October 25, 2022. https://www.livestrong.com/article/13730816-crossfit-statistics/
  2. 2.0 2.1 2.2 2.3 2.4 2.5 2.6 Ángel Rodríguez M, García-Calleja P, Terrados N, Crespo I, Del Valle M, Olmedillas H. Injury in CrossFit®: A Systematic Review of Epidemiology and Risk Factors. Phys Sportsmed. 2022;50(1):3-10. doi:10.1080/00913847.2020.1864675
  3. 3.0 3.1 3.2 Claudino JG, Gabbett TJ, Bourgeois F, et al. CrossFit Overview: Systematic Review and Meta-analysis. Sports Med - Open. 2018;4:11. doi:10.1186/s40798-018-0124-5
  4. Barranco-Ruiz Y, Villa-González E, Martínez-Amat A, Da Silva-Grigoletto ME. Prevalence of Injuries in Exercise Programs Based on Crossfit®, Cross Training and High-Intensity Functional Training Methodologies: A Systematic Review. J Hum Kinet. 2020;73:251-265. doi:10.2478/hukin-2020-0006
  5. Mueller-Wohlfahrt HW, Haensel L, Mithoefer K, et al. Terminology and classification of muscle injuries in sport: The Munich consensus statement. Br J Sports Med. 2013;47(6):342-350. doi:10.1136/bjsports-2012-091448
  6. 6.0 6.1 6.2 6.3 6.4 6.5 6.6 6.7 Alekseyev K, John A, Malek A, et al. Identifying the Most Common CrossFit Injuries in a Variety of Athletes. Rehabil Process Outcome. 2020;9:1179572719897069. doi:10.1177/1179572719897069
  7. 7.0 7.1 Bergeron MF, Nindl BC, Deuster PA, et al. Consortium for Health and Military Performance and American College of Sports Medicine consensus paper on extreme conditioning programs in military personnel. Curr Sports Med Rep. 2011;10(6):383-389. doi:10.1249/JSR.0b013e318237bf8a
  8. Weisenthal BM, Beck CA, Maloney MD, DeHaven KE, Giordano BD. Injury Rate and Patterns Among CrossFit Athletes. Orthop J Sports Med. 2014;2(4):2325967114531177. doi:10.1177/2325967114531177
  9. Hopkins BS, Cloney MB, Kesavabhotla K, et al. Impact of CrossFit-Related Spinal Injuries. Clin J Sport Med Off J Can Acad Sport Med. 2019;29(6):482-485. doi:10.1097/JSM.0000000000000553
  10. Trafimow JH, Schipplein OD, Novak GJ, Andersson GB. The effects of quadriceps fatigue on the technique of lifting. Spine. 1993;18(3):364-367. doi:10.1097/00007632-199303000-00011
  11. 11.0 11.1 Hartmann H, Wirth K, Klusemann M. Analysis of the load on the knee joint and vertebral column with changes in squatting depth and weight load. Sports Med Auckl NZ. 2013;43(10):993-1008. doi:10.1007/s40279-013-0073-6
  12. Fisker FY, Kildegaard S, Thygesen M, Grosen K, Pfeiffer-Jensen M. Acute tendon changes in intense CrossFit workout: an observational cohort study. Scand J Med Sci Sports. 2017;27(11):1258-1262. doi:10.1111/sms.12781
  13. Gabow PA, Kaehny WD, Kelleher SP. The spectrum of rhabdomyolysis. Medicine (Baltimore). 1982;61(3):141-152. doi:10.1097/00005792-198205000-00002
  14. Larsen C, Jensen MP. [Rhabdomyolysis in a well-trained woman after unusually intense exercise]. Ugeskr Laeger. 2014;176(25):V01140001.
  15. Witvrouw E, Mahieu N, Danneels L, McNair P. Stretching and injury prevention: an obscure relationship. Sports Med Auckl NZ. 2004;34(7):443-449. doi:10.2165/00007256-200434070-00003
  16. Cruz-Díaz D, Hita-Contreras F, Martínez-Amat A, Aibar-Almazán A, Kim KM. Ankle-Joint Self-Mobilization and CrossFit Training in Patients With Chronic Ankle Instability: A Randomized Controlled Trial. J Athl Train. 2020;55(2):159-168. doi:10.4085/1062-6050-181-18
  17. de Souza RAS, da Silva AG, de Souza MF, et al. A Systematic Review of CrossFit® Workouts and Dietary and Supplementation Interventions to Guide Nutritional Strategies and Future Research in CrossFit®. Int J Sport Nutr Exerc Metab. 2021;31(2):187-205. doi:10.1123/ijsnem.2020-0223
  18. Middlekauff ML, Egger MJ, Nygaard IE, Shaw JM. The impact of acute and chronic strenuous exercise on pelvic floor muscle strength and support in nulliparous healthy women. Am J Obstet Gynecol. 2016;215(3):316.e1-7. doi:10.1016/j.ajog.2016.02.031
  19. Eather N, Morgan PJ, Lubans DR. Effects of exercise on mental health outcomes in adolescents: Findings from the CrossFitTM teens randomized controlled trial. Psychol Sport Exerc. 2016;26:14-23. doi:10.1016/j.psychsport.2016.05.008
  20. 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
  21. Álvarez-García C, Doğanay M. The prevalence of urinary incontinence in female CrossFit practitioners: A systematic review and meta-analysis. Arch Esp Urol. 2022;75(1):48-59.
  22. Friedman MV, Stensby JD, Hillen TJ, Demertzis JL, Keener JD. Traumatic Tear of the Latissimus Dorsi Myotendinous Junction: Case Report of a CrossFit-Related Injury. Sports Health. 2015;7(6):548-552. doi:10.1177/1941738115595975
  23. oondeph SA, Joondeph BC. Retinal Detachment due to CrossFit Training Injury. Case Rep Ophthalmol Med. 2013;2013:189837. doi:10.1155/2013/189837
  24. Lu A, Shen P, Lee P, et al. CrossFit-related cervical internal carotid artery dissection. Emerg Radiol. 2015;22(4):449-452. doi:10.1007/s10140-015-1318-5
  25. Alexandrino GM, Damásio J, Canhão P, et al. Stroke in sports: a case series. J Neurol. 2014;261(8):1570-1574. doi:10.1007/s00415-014-7383-y
Created by:
John Kiel on 1 February 2023 22:18:11
Last edited:
3 May 2024 00:40:03
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