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

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 VO_2max, 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 HR_max; 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.