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Table 1 Main findings of CrossFit’s scientific state of the art

From: CrossFit Overview: Systematic Review and Meta-analysis

Article (1st author) Aspects (type) Sample (profile; n) Intervention or method of analysis Experimental design Main findings
2013 Hak [34] Injury risk Trained people (n = 132) By electronic questionnaire with people who had trained in CrossFit affiliates Descriptive epidemiological study 74% of practitioners had suffered at least one injury while practicing CrossFit. The most common injury sites were the shoulder, lower back, and followed by arm/elbow with an injury rate of 3.1 per 1000 h.
2013 Joondeph [35] Injury risk Trained person (n = 1) Traumatic retinal detachment occurring as result of CrossFit workout doing pull-ups with an elastic band tied around his waist and secured to the pull-up bar thus partially supporting his weight Case report Retina was successfully recovered and vision was normal after 4 months of follow-up.
2014 Alexandrino [37] Life and health Trained person (n = 1) Sports-related stroke registries Case series A case of stroke type intracerebral hemorrhage during CrossFit training with follow-up of 4 months. Study conclusion confirmed that stroke during sport activity is rare and occurs mostly in heathy young males.
2014 Heinrich [38] Body composition and psycho-social behavior Sedentary (n = 20) 8 weeks of CrossFit training Chronic effects CrossFit practitioners were able to maintain exercise enjoyment and were more likely to intend to continue. No significant changes in body composition were found.
2014 Larsen [39] Life and health Trained person (n = 1) Sports-related rhabdomyolysis registry Case report CrossFit practitioner had reported a rhabdomyolysis diagnostic after CrossFit training.
2014 Partridge [40] Psycho-social behavior Trained people (n = 144) By electronic questionnaire with people who had trained in CrossFit affiliates Descriptive epidemiological study The inclusivity is highlighted in CrossFit. However, motivational climate and goals in CrossFit may vary based on demographic variables (i.e., gender and length of time in a program) and that these differences may impact how to most effectively motivate, encourage, and instruct group members.
2014 Weisenthal [41] Injury risk Trained people (n = 381) By electronic questionnaire with people who had trained in CrossFit affiliates Descriptive epidemiological study 19% of practitioners had suffered at least one injury while practicing CrossFit. the shoulder and lower back were the most commonly injured in gymnastic and power lifting movements, respectively.
2015 Bellar [42] Physiological Competitors (n = 21) and physically active (n = 11) Session 01: 12 throws of a 9.07-kg medicine ball at a 3.05-m target, 12 swings of a 16.38-kg kettlebell, and 12 burpee pull-ups (AMRAP during 12 min) Correlational study AMRAP workout performance was associated with both aerobic fitness and anaerobic power.
Session 02: sumo deadlift high pull, 0.5-m box jump, and 40-m farmer’s walk gripping two 20 kg bumper plates (21/15/9 = 21 repetitions in round one, 15 repetitions in round two, and 9 repetitions in round three)
2015 Butcher [43] Physiological Trained people (n = 14) Grace: 30 clean and jerks for time Correlational study CrossFit benchmark WOD performance cannot be predicted by VO2max, Wingate power/capacity, or either respiratory compensation or anaerobic thresholds.
Fran: three rounds of thrusters and pull-ups for 21, 15, and 9 repetitions
Cindy: 20 min of rounds of 5 pull-ups,10 push-ups, and 15 bodyweight squats
CrossFit total: 1 repetition max back squat, overhead press, and deadlift.
2015 Fernandez [44] Physiological Trained people (n = 10) Fran: three rounds of thrusters and pull-ups for 21, 15, and 9 repetitions Acute effects Both WODs could be characterized as high intensity workouts, achieving near maximal physiological (e.g., 90–95% of HRmax; blood lactate values > 10 mmol− 1) and perceptual responses (e.g., RPE values > 8).
Cindy: 20 min of rounds of 5 pull-ups,10 push-ups, and 15 air-squats
2015 Friedman [45] Injury risk Trained person (n = 1) Magnetic resonance imaging examination demonstrated a high-grade tear of the right latissimus dorsi myotendinous junction. Initial injury occurred while performing a muscle up exercise. Case report This competitor was treated conservatively and was able to resume active CrossFit training within 3 months. At 6 months post-injury, he had only a mild residual functional deficit compared with his pre-injury level.
2015 Heinrich [46] Body composition, physiological and psycho-social behavior Sedentary (n = 6) 5 weeks of CrossFit training Chronic effects CrossFit training to cancer survivors had provoked significant improvements in emotional functioning, body composition (i.e., lean mass, fat mass and body fat percentage), balance, carrying a weighted object, lower body strength and power, aerobic capacity and endurance, and perceived difficulty for flexibility.
2015 Kliszczewicz [47] Physiological Physically active (n = 10) Cindy: 20 min of rounds of 5 pull-ups,10 push-ups, and 15 air-squats Acute effects The Cindy bout elicited an acute blood oxidative stress response comparable to a traditional bout of high-intensity treadmill running.
2015 Lu [48] Life and health Trained people (n = 3) Magnetic resonance imaging examination demonstrated the cervical internal carotid artery dissection Case report While direct causality cannot be proven, intense CrossFit workouts may have led to the internal carotid artery dissections in these practitioners.
2015 Martínez [49] Psycho-social behavior Physically active (n = 104) 8 CrossFit sessions during a didactic unit in the school Chronic effects CrossFit practice during physical education lessons have shown high levels of enjoyment, effort, and learning perception in the students. Furthermore, boys perceive higher enjoyment and intensity than girls.
2015 Murawska [50] Body composition and physiological Physically active (n = 12) 12 weeks of CrossFit training Chronic effects CrossFit training had beneficial influence on the practitioners’ body composition, anaerobic capacity and cardiovascular fitness as well as an increase in brain-derived neurotrophic factor (a protein that stimulates processes of neurogenesis).
2015 Shaw [51] Physiological Sedentary (n = 12) CrossFit triplet: 3 burpees, 4 push-ups, and 5 squats Acute effects This WOD can be considered moderate to high intensity (heart rate ~ 108 bpm; blood lactate ~ 6 mmol/L) and is of sufficient intensity and safety (no significant changes in blood pressure, blood glucose, total cholesterol, and pulse and arterial pressure).
2016 Eather [53] Psycho-social behavior Physically active (n = 51) 8 weeks of CrossFit teens training Chronic effects CrossFit teens training did not improve mental health outcomes in the full students. However, the results from this study provides preliminary evidence for improving mental health in adolescents “at risk” of developing psychological disorders.
2016 Eather [54] Body composition, physiological and psycho-social behavior Physically active (n = 51) 8 weeks of CrossFit teens training Chronic effects CrossFit teens training had improved body composition (i.e., waist circumference, BMI) and results in performance tests (i.e., sit and reach, standing jump, and shuttle run). Retention was 82%, adherence was 94%, and satisfaction ranged from 4.2 to 4.6 out of 5 (1 = strongly disagree to 5 = strongly agree)
2016 Fisher [55] Psycho-social Behavior Trained people (n = 314) By electronic questionnaire with people who had trained in CrossFit affiliates, group resistance exercise, alone and personal trainer Descriptive epidemiological study The study findings suggest that the motivations for engaging in CrossFit may be similar to those seen in sport participation and therefore may have an influence on facilitating long-term adherence in comparison with other resistance exercise modalities.
2016 Fisker [5] Biomechanical Trained people (n = 34) 5 rounds, 5 front squats; 10 box jumps; 15 double unders Acute effects Increased thickness of patellar and Achilles tendons, without changes in Plantar.
2016 Koteles [56] Psycho-social behavior Trained people (n = 186) By electronic questionnaire with people who had trained in CrossFit affiliates Descriptive epidemiological study CrossFit training was not connected with higher levels of psychological functioning (well-being, affect, body awareness, and self-esteem) and satisfaction with body image.
2016 Lichtenstein [57] Psycho-social behavior Trained people (n = 598) By electronic questionnaire with people who had trained in CrossFit affiliates Descriptive epidemiological study This study found a prevalence of exercise addiction of 5% in CrossFit. Exercise addiction is more prevalent in young practitioners (below 30 years) and in males. It is associated with high exercise volumes and negative exercise attitudes that might lead to negative consequences such as injuries and loss of social relations.
2016 Middlekauff [58] Life and health Physically active (n = 70) CrossFit: 15 push-ups, 5 deadlifts at 80% of 3 repetition maximum, 5 push-presses at 80% of 3RM, 15 burpees, and 20 sit-ups Acute and chronic effects Acute: after an exercise bout typical for each group, vaginal support and vaginal resting pressure decreased slightly in both groups.
Walking: 20-min walk at their self-selected exercise pace   Chronic: the strenuous exercise did not promote beneficial or deleterious effects for nulliparous women. Pelvic floor muscle strength did not change.
2016 Perciavalle [59] Physiological Competitors (n = 15) WOD 15.5: Thrusters + rowing with 29/27/15/9 repetitions Acute effects High levels of blood lactate negatively impacted the performance of dual task attention and reaction time.
2016 Pickett [60] Psycho-social behavior Trained people (n = 276) By questionnaire with people who had trained in CrossFit affiliates, group exercises, or individual exercise programs Descriptive epidemiological study The study found that the explicit community-building mantra encouraged by CrossFit was successful in creating greater levels of felt sense of community than other fitness outlets.
2016 Sprey [4] Injury risk Trained people (n = 622) By electronic questionnaire with people who had trained in CrossFit affiliates Descriptive epidemiological study 31% of practitioners had experienced some type of injury while practicing CrossFit.
2016 Summitt [61] Injury risk Trained people (n = 187) By electronic questionnaire with people who had trained in CrossFit affiliates Descriptive epidemiological study 24% of practitioners had suffered at least one shoulder injury in the last 6 months. Injury rate was 1.9 per 1000 h.
2016 Tibana [62] Physiological Trained people (n = 9) WOD 01: 5× snatch (80% 1MR with 2–5 min of rest); 3 × 5 of touch and go snatches full (75% 5MR with 90 s of rest); 3 × 60 s of weighted plank hold (90 s of rest); after 5 min of rest: 10 s of as many round as possible (AMRAP) of 30 double unders and 15 power snatches (34 kg). WOD 02: 5× clean and jerk box (80% 1MR with 2–5 min of rest); 3 × 5 of touch and go cleans full (70% 5MR with 2–5 min of rest); 3 × 10 of strict hand standing push-ups; after 5 min of rest: 12 min of AMRAP of row 250 m and 25 target burpees Acute effects in 2 consecutive days Increases in blood glucose and lactate levels, along with pro and anti-inflammatory cytokines but without interfering in muscle performance for the next training session.
2016 Whiteman [63] Psycho-social behavior Trained people (n = 100) By questionnaire with people who had trained in CrossFit affiliates and traditional gym Descriptive epidemiological study The study found that CrossFit may offer a greater sense of community level compared with a traditional gym. Specifically, CrossFit practitioners had higher levels of social capital and feelings of community belongingness than members of a similar traditional gym.
2017 Drum [52] Physiological, life, and health Trained people (n = 157) By electronic questionnaire with people who had trained in CrossFit affiliates and ACSM-certified personal trainers clinics Descriptive epidemiological study CrossFit was perceived as strenuous or “very hard” activity by practitioners as well as they have been reporting a feeling of excessive fatigue, muscle pain and swelling, and limb movement difficulties within 48 h after a workout. A practitioner was diagnosed with rhabdomyolysis.
  1. ACSM American College of Sports Medicine, AMRAP as many rounds as possible, BMI body mass index, bpm beats per minute, HR max maximum heart rate, mmol/L millimole/liter, MR maximum repetitions, RPE ratings of perceived exertion, VO 2max maximal oxygen uptake, WOD workout of the day
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