Impact of CrossFit Workouts on Different Aspects of Physical Fitness, with Emphasis on Military Fitness: Narrative Review

Document Type : Review

Authors

1 MSc in Exercise physiology, Shahed University, Tehran, Iran

2 Shahed Univercity

Abstract

CrossFit is an exercise program designed to provide general and inclusive physical fitness and improves fitness in all 10 areas including cardiovascular and respiratory endurance, muscle endurance and strength, power, flexibility, speed, coordination and agility. This is especially important for the military population, which must be physically fit to respond to specific occupational and combat missions.
Findings show that the CrossFit program and other functional fitness programs present the U.S. Army with unique opportunities to improve Soldiers’ fitness levels as well as trigger the acute cardiovascular training response and a significant increase in fitness (ie, aerobic and anaerobic performance). Research has shown that CrossFit workouts significantly increases the bone mineral content of legs and trunk in men and women.
The results of limited studies in CrossFit workouts show that this exercise improves the physical fitness of the participants. According to the available documentation, if CrossFit workouts is done with the proper intensity, duration, and monitoring, its physiological changes may be helpful for the combat forces. Carbohydrate diets are particularly important, according to recent studies, CrossFit workouts with low-carbohydrate diets leads to reduced body fat and with high-carbohydrate diets result in improving performance. Studies showed that Crossfit workouts are associated with improved intrinsic motivation to improve the enjoyment of exercise, satisfaction, motivation, mood, and reduce stress. Injuries related to CrossFit workouts have a similar or even lower profile than other sports and improve overall fitness the same or even better than traditional distance running and strength training. Therefore, available studies, it can be said that CrossFit workouts along with other physical fitness programs may help military combat readiness, but further studies are needed.

Keywords


1. Glassman G. The crossfit training guide. CrossFit Journal. 2010;30(1):1-115. 2. Heinrich KM, Patel PM, O'Neal JL, Heinrich BS. High-intensity compared to moderate-intensity training for exercise initiation, enjoyment, adherence, and intentions: an intervention study. BMC public health. 2014;14(1):789. doi:10.1186/1471-2458-14-789 3. Baghinzadeh M, Abbasi B. Crossfit comprehensive training book: Daneshparvar; 2019. 4. Glassman G. Crossfit Training Guide L1 2018 [Available from: www.crossfit.com. 5. Poston WS, Haddock CK, Heinrich KM, Jahnke SA, Jitnarin N, Batchelor DB. Is high-intensity functional training (HIFT)/CrossFit safe for military fitness training? Military medicine. 2016;181(7):627-37. doi:10.7205/MILMED-D-15-00273 6. Shakibaee A, Rahimi M, Bazgir B, Asgari A. A review on physical fitness studies in military forces. EBNESINA. 2015;16(4):64-79. 7. Paine J, Uptgraft J, Wylie R. CrossFit study. Command and General Staff College. 2010:1-34. doi:10.21236/ADA560056 8. 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 and tendons journal. 2016;6(1):157. doi:10.32098/mltj.01.2016.19 9. Meyer J, Morrison J, Zuniga J. The benefits and risks of CrossFit: a systematic review. Workplace health & safety. 2017;65(12):612-8. doi:10.1177/2165079916685568 10. Smith MM, Sommer AJ, Starkoff BE, Devor ST. Crossfit-based high-intensity power training improves maximal aerobic fitness and body composition. J Strength Cond Res. 2013;27(11): 3159-72. doi:10.1519/JSC.0b013e318289e59f 11. Feito Y, Burrows EK, Tabb LP. A 4-Year Analysis of the Incidence of Injuries Among CrossFit-Trained Participants. Orthopaedic Journal of Sports Medicine. 2018;6(10). doi:10.1177/2325967118803100 12. Beilke C, Hetzel L, Kreft B, Pan L, Schroeder J. CrossFit Training Improvements in Sport Performance and Body Composition in Young Healthy Adults. 2012. 13. Butcher SJ, Neyedly TJ, Horvey KJ, Benko CR. Do physiological measures predict selected CrossFit® benchmark performance? Open access journal of sports medicine. 2015;6:241. doi:10.2147/OAJSM.S88265 14. Butcher SJ, Judd TB, Benko CR, Horvey KJ, Pshyk AD. Relative intensity of two types of CrossFit exercise: Acute circuit and high-intensity interval exercise. Journal of Fitness Research. 2015;4(2):3-15. 15. Barfield J, Anderson A. Effect of CrossFit™ on health-related physical fitness: A pilot study. Journal of Sport and Human Performance. 2014;2(1):23-8. 16. Eather N, Morgan PJ, Lubans DR. Improving health-related fitness in adolescents: the CrossFit Teens™ randomised controlled trial. Journal of sports sciences. 2016;34(3):209-23. doi:10.1080/02640414.2015.1045925 17. Goins JM. Physiological and Performance effects of CrossFit: University of Alabama Libraries; 2014. doi:10.1249/01.mss.0000493998.84691.5d 18. Dexheimer JD, Schroeder ET, Sawyer BJ, Pettitt RW, Aguinaldo AL, Torrence WA. Physiological Performance Measures as Indicators of CrossFit® Performance. Sports. 2019;7(4):93. doi:10.3390/sports7040093 19. Mangine GT, Cebulla B, Feito Y. Normative values for self-reported benchmark workout scores in crossfit® practitioners. Sports medicine-open. 2018;4(1):39. doi:10.1186/s40798-018-0156-x 20. Fernández JF, Solana RS, Moya D, Marin JMS, Ramón MM. Acute physiological responses during crossfit® workouts. European Journal of Human Movement. 2015;35:114-24. 21. Maté-Muñoz JL, Lougedo JH, Barba M, Cañuelo-Márquez AM, Guodemar-Pérez J, García-Fernández P, et al. Cardiometabolic and Muscular Fatigue Responses to Different CrossFit® Workouts. Journal of Sports Science & Medicine. 2018;17(4):668. 22. Kliszczewicz B, John QC, Daniel BL, Gretchen OD, Michael ER, Kyle TJ. Acute exercise and oxidative stress: CrossFit™ vs. treadmill bout. Journal of human kinetics. 2015;47(1):81-90. doi:10.1515/hukin-2015-0064 23. Feito Y, Hoffstetter W, Serafini P, Mangine G. Changes in body composition, bone metabolism, strength, and skill-specific performance resulting from 16-weeks of HIFT. PloS one. 2018;13(6):e0198324. doi:10.1371/journal.pone.0198324 24. Perciavalle V, Marchetta NS, Giustiniani S, Borbone C, Perciavalle V, Petralia MC, et al. Attentive processes, blood lactate and CrossFit®. The Physician and sportsmedicine. 2016;44(4):403-6. doi:10.1080/00913847.2016.1222852 25. Sarah L Dunn, Winnie Siu, Judith Freund, Stephen H Boutcher. The effect of a lifestyle intervention on metabolic health in young women. 2014. 26. Bagheinzadeh M, Nahid T. Comparison of the effect of traditional and CrossFit resistance training on FFMI net mass index and FMI fat mass index of overweight and obese adult women. National Conference on Physical Education and Sports Medicine Mashhad University of Medical Sciences 13982019. 27. Fisker F, Kildegaard S, Thygesen M, Grosen K, Pfeiffer‐Jensen M. Acute tendon changes in intense CrossFit workout: an observational cohort study. Scandinavian journal of medicine & science in sports. 2017;27(11):1258-62. doi:10.1111/sms.12781 28. Maxwell C, Ruth K, Friesen C. Sports nutrition knowledge, perceptions, resources, and advice given by certified CrossFit trainers. Sports. 2017;5(2):21. doi:10.3390/sports5020021 29. Gregory RM, Hamdan H, Torisky D, Akers J. A low-carbohydrate ketogenic diet combined with 6-weeks of crossfit training improves body composition and performance. Int J Sports Exer Med. 2017;3:1-10. doi:10.23937/2469-5718/1510054 30. Durkalec-Michalski K, Nowaczyk PM, Siedzik K. Effect of a four-week ketogenic diet on exercise metabolism in CrossFit-trained athletes. Journal of the International Society of Sports Nutrition. 2019;16(1):16. doi:10.1186/s12970-019-0284-9 31. Rountree J, Krings B, Peterson T, Thigpen A, McAllister M, Holmes M, et al. Efficacy of carbohydrate ingestion on crossfit exercise performance. Sports. 2017;5(3):61. doi:10.3390/sports5030061 32. Escobar KA, Morales J, Vandusseldorp TA. The effect of a moderately low and high carbohydrate intake on crossfit performance. International journal of exercise science. 2016;9(4):460. 33. Kephart W, Pledge C, Roberson P, Mumford P, Romero M, Mobley C, et al. The three-month effects of a ketogenic diet on body composition, blood parameters, and performance metrics in CrossFit trainees: a pilot study. Sports. 2018;6(1):1. doi:10.3390/sports6010001 34. Kramer SJ, Baur DA, Spicer MT, Vukovich MD, Ormsbee MJ. The effect of six days of dietary nitrate supplementation on performance in trained CrossFit athletes. Journal of the International Society of Sports Nutrition. 2016;13(1):39. doi:10.1186/s12970-016-0150-y 35. Sales A, Fisher J, Carlson L, Steele J, Fisher J, Terrace EP, et al. A comparison of the motivational factors between CrossFit participants and other exercise modalities. 2016. 36. Kaus RJ. Affect and enjoyment associated with crossfit exercise: Bowling Green State University; 2014. 37. Partridge JA, Knapp BA, Massengale BD. An investigation of motivational variables in CrossFit facilities. The Journal of Strength & Conditioning Research. 2014;28(6):1714-21. doi:10.1519/JSC.0000000000000288 38. Claudino JG, Gabbett TJ, Bourgeois F, de Sá Souza H, Miranda RC, Mezêncio B, et al. Crossfit overview: systematic review and meta-analysis. Sports medicine-open. 2018;4(1):11. doi:10.1186/s40798-018-0124-5 39. Sławińska M, Stolarski M, Jankowski KS. Effects of chronotype and time of day on mood responses to CrossFit training. Chronobiology international. 2019;36(2):237-49. doi:10.1080/07420528.2018.1531016 40. Lichtenstein MB, Jensen TT. Exercise addiction in CrossFit: Prevalence and psychometric properties of the Exercise Addiction Inventory. Addictive Behaviors Reports. 2016;3:33-7. doi:10.1016/j.abrep.2016.02.002 41. Brupbacher G, Harder J, Faude O, Zahner L, Donath L. Music in CrossFit®-influence on performance, physiological, and psychological parameters. Sports. 2014;2(1):14-23. doi:10.3390/sports2010014 42. Maibach M. Feelings in CrossFit: The Relationship between High Intensity Physical Activity and A ffective Responses. 2013. 43. Sprey JW, Ferreira T, de Lima MV, Duarte Jr A, Jorge PB, Santili C. An epidemiological profile of crossfit athletes in Brazil. Orthopaedic journal of sports medicine. 2016;4(8). doi:10.1177/2325967116663706 44. Klimek C, Ashbeck C, Brook AJ, Durall C. Are injuries more common with CrossFit training than other forms of exercise? Journal of sport rehabilitation. 2018;27(3):295-9. doi:10.1123/jsr.2016-0040 45. Hopkins BS, Li D, Svet M, Kesavabhotla K, Dahdaleh NS. CrossFit and rhabdomyolysis: A case series of 11 patients presenting at a single academic institution. Journal of science and medicine in sport. 2019;22(7):758-62. doi:10.1016/j.jsams.2019.01.019 46. Hopkins BS, Cloney MB, Kesavabhotla K, Yamaguchi J, Smith ZA, Koski TR, et al. Impact of CrossFit-related spinal injuries. Clinical journal of sport medicine. 2019;29(6):482-5. doi:10.1097/JSM.0000000000000553 47. Mehrab M, de Vos R-J, Kraan GA, Mathijssen NM. Injury incidence and patterns among Dutch CrossFit athletes. Orthopaedic journal of sports medicine. 2017;5(12). doi:10.1177/2325967117745263 48. Minghelli B, Vicente P. Musculoskeletal injuries in Portuguese CrossFit practitioners. J Sports Med Phys Fitness. 2019. doi:10.23736/S0022-4707.19.09367-8 49. Montalvo AM, Shaefer H, Rodriguez B, Li T, Epnere K, Myer GD. Retrospective injury epidemiology and risk factors for injury in CrossFit. Journal of sports science & medicine. 2017;16(1):53. 50. Maté-Muñoz JL, Lougedo JH, Barba M, García-Fernández P, Garnacho-Castano MV, Dominguez R. Muscular fatigue in response to different modalities of CrossFit sessions. PloS one. 2017;12(7):e0181855. doi:10.1371/journal.pone.0181855 51. Drum SN, Bellovary BN, Jensen RL, Moore MT, Donath L. Perceived demands and postexercise physical dysfunction in CrossFit® compared to an ACSM based training session. J Sports Med Phys Fitness. 2017;57(5):604-9.