An Epidemiological Profile of CrossFit Athletes in Brazil

Effects of Acute Citrulline Malate Supplementation on CrossFit® Exercise Performance: A Randomized, Double-Blind, Placebo-Controlled, Cross-Over Study

Given the increasing popularity of CrossFit® as a high-intensity functional training program and the potential benefits of citrulline malate (CM) in enhancing exercise performance through its role as a precursor to L-arginine and nitric oxide production, this study aimed to investigate the acute effects of CM supplementation on CrossFit® performance and cardiovascular function. Using a randomized, double-blind, placebo-controlled, cross-over design, 21 recreationally active participants (mean age 22.2 ± 2.6 years, mean body weight 75.9 ± 10.4 kg) with CrossFit® experience completed the "Cindy" workout under CM and placebo conditions. Participants consumed 4.4 g of CM or a placebo 60 min before the workout, and the performance was measured by the number of rounds completed. Secondary outcomes included heart rate response, time spent in different heart rate intensity zones, and post-exercise recovery time. The results indicated no significant difference in the number of rounds completed between the CM and placebo conditions (13.5 ± 5.2 vs. 13.8 ± 6.7 rounds, respectively; p = 0.587). However, the time spent in zone 4 (80-90% of HR max) was significantly increased in the CM condition (527 ± 395 s vs. 453 ± 334 s; p = 0.017), suggesting a potential benefit for aerobic capacity and anaerobic threshold. No significant differences in post-exercise recovery time were observed (6.6 ± 4.7 h vs. 6.9 ± 4.7 h; p = 0.475). This study highlights the need for further research with larger sample sizes, both genders, and different CM dosages to clarify these findings and better understand CM's role in enhancing athletic performance.

Exploring the Molecular Adaptations, Benefits, and Future Direction of Exercise Training: Updated Insights into Cardiovascular Health

This review emphasizes the globally accepted physical activity guidelines and explores the various molecular adaptations that occur with continuous exercise. It is essential to highlight the critical roles of cardiorespiratory fitness, muscular strength, and muscle mass in reducing mortality and enhancing quality of life. It has been shown in various studies that there are certainly substantial reductions in cardiovascular and all-cause mortality among individuals with high cardiorespiratory fitness levels. Resistance training is also examined, which, likewise, reveals significant mortality benefits, even with minimal weekly engagement. When delving into the molecular mechanisms, it is apparent that exercise training favorably influences certain cardiovascular conditions, mostly owing to its effect on enhanced lipid metabolism, improvement in glucose regulation, ability to modulate inflammation and oxidative processes, and induction of other cardioprotective effects like improved sympathetic tone and left ventricular remodeling. Cardiovascular diseases and malignancy also share the same risk factors, which explains why exercise can also mitigate the risk of developing many types of cancers. But despite these advancements in research, cardiovascular diseases continue to be prevalent, which may suggest the need to devise other means of promoting physical activity involvement. These approaches may include a greater emphasis on the societal benefits of increased exercise adherence, facilitated by community involvement and technological advancements in fitness tracking devices. We conclude that the future directions for exercise research should emphasize the need for personalized or tailored exercise programs to make it more engaging, accessible, and inclusive for a diverse set of people.

Exploring CrossFit performance prediction and analysis via extensive data and machine learning

BACKGROUND

The analysis of athletic performance has always aroused great interest from sport scientist. This study utilized machine learning methods to build predictive models using a comprehensive CrossFit (CF) dataset, aiming to reveal valuable insights into the factors influencing performance and emerging trends.

METHODS

Random forest (RF) and multiple linear regression (MLR) were employed to predict performance in four key weightlifting exercises within CF: clean and jerk, snatch, back squat, and deadlift. Performance was evaluated using R-squared (R2) values and mean squared error (MSE). Feature importance analysis was conducted using RF, XGBoost, and AdaBoost models.

RESULTS

The RF model excelled in deadlift performance prediction (R2=0.80), while the MLR model demonstrated remarkable accuracy in clean and jerk (R2=0.93). Across exercises, clean and jerk consistently emerged as a crucial predictor. The feature importance analysis revealed intricate relationships among exercises, with gender significantly impacting deadlift performance.

CONCLUSIONS

This research advances our understanding of performance prediction in CF through machine learning techniques. It provides actionable insights for practitioners, optimize performance, and demonstrates the potential for future advancements in data-driven sports analytics.

Inter-Rater and Test-Retest Reliability of an Innovative Evaluation Tool: CrossFit Functional Assessment Battery of Tests for the Shoulder Joint

Background and objectives This study aims to introduce an innovative functional assessment tool designed for CrossFit athletes, to identify a high risk of injury at the shoulder joint. Additionally, the study seeks to examine both inter-rater reliability, which was tested in 40 CrossFit participants, and test-retest reliability, which was assessed in twenty subjects. Methodology CrossFit Functional Assessment Battery for the Shoulder Joint (CrossFit FABS) is a newly created instrument presented for the first time. The evaluation of the performance of its six items aimed to reveal deficits that could contribute to incidents of shoulder injuries. For this purpose, 40 healthy CrossFit participants were concurrently but independently examined by two raters, and twenty healthy adults active in sports were assessed by the main investigator at two different time points. Cohen's kappa coefficient was used to analyze categorical data with an ordinal structure. Results Inter-rater reliability ranged from 0.824 to 1 (P = 0.000) and test-retest reliability was 0.661 to 0.906 (P < 0.001) for each test of CrossFit FABS. A strong to almost perfect correlation was demonstrated for all the variables between the two examiners. Moderate to almost perfect correlation was shown through test-retest procedures. Conclusions The proposed test battery was established as a reliable tool for evaluating performance routines that represent high injury-risk elements for the shoulder joint in CrossFit athletes.

Effects of high-intensity functional training on physical fitness and sport-specific performance among the athletes: A systematic review with meta-analysis

OBJECTIVE

This study aims to meta-analyze the impact of high-intensity functional training on athletes' physical fitness and sport-specific performance.

METHODS

A systematic search was conducted in five well-known academic databases (PubMed, Scopus, Web of Science, EBSCOhost, and the Cochrane Library) up to July 1, 2023. The literature screening criteria included: (1) studies involving healthy athletes, (2) a HIFT program, (3) an assessment of outcomes related to athletes' physical fitness or sport-specific performance, and (4) the inclusion of randomized controlled trials. The Physical Therapy Evidence Database (PEDro) scale was used to evaluate the quality of studies included in the meta-analysis.

RESULTS

13 medium- and high-quality studies met the inclusion criteria for the systematic review, involving 478 athletes aged between 10 and 24.5 years. The training showed a small to large effect size (ES = 0.414-3.351; all p < 0.05) in improving upper and lower body muscle strength, power, flexibility, and sport-specific performance.

CONCLUSION

High-intensity functional training effectively improves athletes' muscle strength, power, flexibility, and sport-specific performance but has no significant impact on endurance and agility. Future research is needed to explore the impact of high-intensity functional training on athletes' speed, balance, and technical and tactical performance parameters.

Differential improvements between men and women in repeated CrossFit open workouts

INTRODUCTION

The CrossFit® Open (CFO) acts a preliminary round that qualifies men and women for later stages of its annual Games competition. The CFO typically consists of 4-6 workouts that variably challenge an athlete's weightlifting strength, gymnastic skill, and endurance capacity. Except for differences in prescribed intensity loads, workouts are designed the same for men and women to elicit a similar challenge. While all workouts within a single year are unique to each other, one has been repeated from a previous CFO each year between 2012 and 2021. Because previous CFO workouts are often integrated into training, improvements are expected when a workout is officially repeated. However, besides documented record performances, it is unclear whether most athletes are improving, if these improvements affect ranking, or if differences exist between men and women.

PURPOSE

To examine sex-division differences and performance changes across repeated CFO workouts, as well as their effect on CFO and workout ranking.

METHODS

Eleven separate samples of 500 men and 500 women, who were representative of the same overall percent rank within each year involving one of the nine repeated CFO workouts (2011-2021) were drawn for this study. Each athlete's age (18-54 years), rank (overall and within each workout), and reported workout scores were collected from the competition's publicly-available leaderboard. Each sample had excluded any athlete who had not met minimum performance criteria (e.g., at least one completed round) for all prescribed (Rx) workouts within a given year (including those not analyzed). Since some workouts could be scored as repetitions completed or time-to-completion (TTC), and because programming was often scaled between men and women, all scores were converted to a repetition completion rate (repetitions divided by TTC [in minutes]).

RESULTS

Separate sex-division x time analyses of variance with repeated measures revealed significant (p < 0.05) interactions in all but one repeated workout comparison. Initially, men were faster in four workouts (~18.5%, range = 3.9-35.0%, p < 0.001), women in two (~7.1%, range = 5.2-9.0%, p < 0.001), and they tied in the remaining three workouts. When workouts were repeated in subsequent years, men were faster in three workouts (~5.4%, range = 0.9-7.8%, p < 0.05), while women were faster in two (~3.8%, range = 3.5-4.1%, p < 0.01). Though performance improved in seven of the nine workouts (~14.3%, p < 0.001) and percentile rank was controlled, athletes earned a lower rank (overall and within workout) on each repeated workout (p < 0.001).

CONCLUSIONS

Performance (measured as repetition completion rate) has improved in most repeated CFO workouts, particularly for women. However, improvements seen among all athletes, along with increased participation, have made it more difficult for athletes to improve their overall rank. To rank higher, individual athletes must improve their pace to a greater degree than the average improvements seen across the competitive field.

Musculoskeletal Injury Prevalence, Pain Perception, and Physical Activity Level Among Brazilian Strength and Cross-Training Practitioners

In this study, we sought to determine the prevalence of musculoskeletal injuries, perceived pain, and physical activity level among Brazilian practitioners of strength training (ST) and functional fitness (FF). Participants were 311 men and women who trained in 10 FF training centers and seven ST gyms. Each participant completed surveys of the prevalence of musculoskeletal injuries, their pain perception, and their physical activity level. A chi square test was used to analyze associations between groups and distributions of injuries. When any significant difference was observed, the difference score was analyzed through the adjusted residual values. Fisher's exact test was used to determined the associations between musculoskeletal injury prevalence and training modality (FF and ST) and between musculoskeletal injury prevalence and practice frequency (times/wk). To measure the magnitude of association between variables, the Phi coefficient was calculated for 2x2 associations and Cramer's V was used whenever the distributions were outside this standard. When the dependent variable presented a dichotomous characteristic, an Odds Ratio (OR) was calculated with a confidence interval of 95%. We found a higher musculoskeletal injury prevalence in the axial skeleton (n = 52; 83.88%) in FF practitioners and in the lower limbs of ST practitioners (n = 9; 52.96%). When the physical activity level cutoff point was set at 300 minutes per week, there was a significant relationship between physical activity and training modality (p = 0.005). There was also a significant association between pain perception and musculoskeletal injury (p < 0.001). Clinical follow-up was a protective factor to being injured (OR = 0.18; CI = 0.06-0.49), and, even after multivariate analysis this significant association was maintained (OR = 0.03; CI = 0.01 - 0.08). Thus, FF practitioners reported more musculoskeletal injuries than STs, and follow-up medical or physical therapy was a protective factor to these injuries. FF practitioners also had a higher level of weekly physical activity weekly than ST practitioners. Functional fitness practitioners may be at a higher risk of injuries than those who participate in traditional strength training.

Prevalence of urinary incontinence in female CrossFit athletes: a systematic review with meta-analysis

INTRODUCTION AND HYPOTHESIS

Studies on the prevalence of urinary incontinence (UI) among CrossFit practitioners are on the rise. This systematic review with meta-analysis was aimed at determining the prevalence of UI among CrossFit practitioners.

METHODS

A systematic review of the literature was performed by searching MEDLINE/PubMed, Scopus, and SPORTDiscus through January 2021. The search strategy included the keywords CrossFit, urine incontinence, exercise, high impact and pelvic floor dysfunction. The inclusion criterion was any study with a sample of CrossFit practitioners and results separated from the other fitness modalities analysed. The subjects were women with no restriction of age, parity, experience or frequency of training. Quality assessment of the studies included was conducted using the Oxford Centre of Evidence-Based Medicine scale and the Newcastle-Ottawa Scale (NOS) adapted for cross-sectional studies.

RESULTS

Thirteen studies (6 comparative and 7 non-comparative) were included for the systematic review, all using a cross-sectional design. The level of evidence was 4, with their quality ranging from poor (n = 10) to fair (n = 3). A total of 4,823 women aged 18 to 71 were included, 91.0% participated in CrossFit, and 1,637 presented UI, which indicates a prevalence of 44.5%. Also, 55.3% and 40.7% presented mild or moderate UI respectively. Stress UI was the most common type reported (81.2%).

CONCLUSIONS

The factors that increased the likelihood of UI were age, body mass index and parity. Exercises based on jumps were commonly associated with urine leakage. CrossFit practitioners presented higher UI than control groups.

Functional assessment of respiratory muscles and lung capacity of CrossFit athletes

CrossFit is a high-intensity training related to physical fitness and respiratory capacity that can promote changes in lung function. This cross-sectional study was aimed at evaluating respiratory muscle strength, electromyographic (EMG) activity, and lung capacity in CrossFit athletes. Thirty subjects aged between 25 and 35 years were divided into groups: CrossFit athletes (n=15) and sedentary individuals without comorbidities (n=15). Respiratory muscle strength was evaluated using maximal inspiratory and expiratory pressures, lung capacity, and EMG of the sternocleidomastoid, serratus anterior, external intercostal, and diaphragm muscles at respiratory rest, maximal inspiration and expiration, and respiratory cycle. Data were tabulated and subjected to statistical analyses (t-test and Spearman test, P<0.05). Respiratory muscle strength on EMG of the sternocleidomastoid, serratus, external intercostal, and diaphragm muscles at the respiratory cycle and maximal forced inspiration and expiration were higher in the CrossFit athletes group than in the sedentary group without comorbidities. CrossFit athlete group showed significantly strong positive correlation between maximal inspiratory and expiratory muscle strengths (Spearman rho= 0.903, P=0.000), with increasing muscle strength during inspiration favoring an increase in strength during expiration. The forced vital capacity (FVC) and forced expiratory volume in 1 sec (FEV₁) also showed a significantly high positive correlation (Spearman rho=0.912, P=0.000) in the CrossFit athletes group, showing that higher FVC favors higher FEV₁. The results of this study suggest that improved fitness is based on increased respiratory muscle strength on EMG in CrossFit athletes.

Epidemiological Profile among Greek CrossFit Practitioners

CrossFit (CF) is a popular and rapidly expanding training program in Greece and worldwide. However, there is a lack of scientific evidence on the risk of musculoskeletal injuries related to CF in the Greek population. A self-administered survey of 1224 Greek CF practitioners aged 18 to 59 was conducted and analyzed using the Statistical Package for Social Sciences (SPSS) software. The highest percentage of the participants (34%) practiced 5 days per week for 60 min (42.2%) and had 2 days per week of rest (41.7%). A total of 273 individuals (23%) participated in CF competitions and 948 (77%) did not. The results showed that the most common injuries were muscle injuries (51.3%), followed by tendinopathies (49.6%) and joint injuries (26.6%). The shoulders (56.6%; n = 303), knees (31.8%; n = 170), and lumbar spine (33.1%; n = 177) were the most commonly injured locations. The logistic regression model showed that participation in competitions (p = 0.001), rest per week (p = 0.01), duration of training per session (p = 0.001), and frequency of training per week (p = 0.03) were statistically significant factors for injury. Training level was not a statistically significant factor for injury (p = 0.43). As CF continues to gain popularity on a global scale and the number of athletes gradually increases, it is important to monitor the safety of practitioners. Clinicians should consider participation in competitions, rest, training duration, and frequency in order to make CF safer.

Risk Factors for Musculoskeletal Injury in CrossFit: A Systematic Review

The objective of this systematic review was to identify potential risk factors for injury in CrossFit participants. Embase, Medline, Web of Science, Cochrane, CINAHL, Google Scholar, and SportDiscuss databases were all searched up to June 2021. Cohort studies that investigated risk factors for CrossFit injuries requiring medical attention or leading to time loss in sports were included. A best-evidence synthesis was performed combining all the outcomes from prospective cohort studies. From 9,452 publications identified, we included three prospective cohort studies from which two had a low risk of bias and one a high risk of bias. The studies examined 691 participants of whom 172 sustained an injury. There was limited evidence that switching between prescribed and scaled loads during training is associated with increased injury risk and that increased duration of participation is a protective factor for injury. This could mean that novice CrossFit athletes and those increasing their training load should have closer supervision by CrossFit coaches. These risk factors should be considered when developing preventive interventions.

Epidemiology of High Intensity Functional Training (HIFT) injuries in Brazil

BACKGROUND

High intensity functional training (HIFT), usually called CrossFit, is a physical training that has gained much popularity in the past few years. The risk of acute and overuse injuries in HIFT is unclear. This study evaluated the incidence of injuries in HIFT, characterizing severity, location, and associated risk factors.

METHODS

This cross-sectional study was conducted between January and May 2021. HIFT practitioners were recruited through social media and answered an online questionnaire on training characteristics and injury history.

RESULTS

A total of 606 subjects (264 male and 342 female) were included. The average age of the participants was 29.78 ± 7.14 years. The mean height was 169.60 ± 8.96 cm, and the mean body mass was 73.69 ± 13.11 kg. Overall, participants were involved in HIFT for an average of 25.36 ± 20.29 months. A total of 58.6% of participants took part in 5 to 6 training sessions per week, 31.7% practiced 5 to 6 h per week. 62.7% of the responders performed other physical activities in parallel, 98.2% performed warm-up before the training, and a formal cooldown was accomplished by 29.4% of participants. 6.8% of athletes followed individual worksheets. 45.9% of participants participated in competition.

CONCLUSIONS

The overall rate of injuries was 3.51/1000 h. 59.2% of subjects experienced two or more injuries. The shoulder was involved in 21.3% of cases, lower back in 18.3%, and the knee in 13.4%. No difference was found in injury rate between males and females. Experienced athletes were more prone to injury compared to those who trained under 12 months. Approximately the half of injuries did not cause training interruption. No difference was found in injury rate between males and females. The purpose of the participant did not impact the injury rate, nor did the practice of warm-up and cooldown, the time of weekly training, the league and level of competition. Finally, the participation in other sports in parallel did not demonstrated association with the injury occurrence.

TRIAL REGISTRATION

The present study was approved by the Ethics and Research Committee by Plataforma Brazil and follows the Resolution 466/2012/CNS/MS/CONEP.

EVALUATION OF SCAPULAR DYSKINESIS IN CROSSFIT®- PRACTICING ATHLETES

Objective

Evaluate the scapular movement of Crossfit® practitioners and identify whether they present an increased incidence of scapular dyskinesis (SD) compared to non-practitioners.

Method

A transversal study was evaluated quantitatively and dynamically, using retro-reflective spherical markers, the scapular movements of ten volunteers composing the control group, and 11 Crossfit® practitioners. The control group's results were used as a normality parameter and compared to those of the Crossfit® practitioner's group.

Results

It was identified that the superior scapular rotation in the ascending phase is inferior in the group of Crossfit® practitioners (p = 0.02).

Conclusion

The regular practice of Crossfit® causes scapular dyskinesis (SD), with alteration in the scapular superior rotation movement. Level of Evidence III: Retrospective comparative .

Predicting the Clean Movement Technique in Crossfit® Athletes Using an Optimal Upper-Limb Range of Motion: A Prospective Cohort Study

BACKGROUND

The aim of this study was to determine the optimal upper-limb range of motion (ROM) profile for the catch phase of the clean movement (CPCM) and to identify the key ROMs for performing the CPCM in CrossFit® athletes.

METHODS

A prospective cohort study of twenty CrossFit® athletes aged 20-36 years was conducted. Data were collected regarding age, anthropometrics, CrossFit® training experience and upper-limb ROM. The ROM was measured using the ROM-SPORT method. After 7 months, athletes performed a clean movement with a load of 80% one repetition maximum. A Bayesian Student's t-analysis, binary logistic regression analysis and Receiver Operating Characteristic analysis were performed.

RESULTS

The optimal upper-limb ROM profile that predicted correct CPCM performance was 78° in shoulder extension, 173° in shoulder flexion, 107° in shoulder external rotation, 89° in shoulder internal rotation, 153° in elbow flexion, 99° in elbow pronation and 92° in wrist extension (area under the curve ≥ 651; positive predictive value ≥ 80%). Shoulder external rotation, elbow pronation and wrist extension were found to be the most important ROMs for the efficient and safe performance of CPCM (area under the curve ≥ 854; positive predictive value ≥ 85.7%).

CONCLUSION

The upper-limb ROM profile is associated with proper clean performance. Further studies are warranted to determine whether improving flexibility on upper-limb ROM may improve proper clean movement performance.

Exercise dependence and orthorexia nervosa in Crossfit: exploring the role of perfectionism

Physical exercise and healthy diet have a positive effect on health. However, the pathological dimension of both behaviors, namely exercise dependence and orthorexia nervosa, can lead to negative results. So far, literature on these behaviors in the context of high-intensity sports is limited. The present study aims for investigating exercise dependence and orthorexia nervosa in a sample of Crossfit athletes, as well as examining the mediating role of perfectionism in their manifestation.The sample consisted of 110 people who attended Crossfit programs and 131 active gym members. The Exercise Dependence Scale was used to assess exercise dependence, the ORTO-15 to assess orthorexic behavior and the Almost Perfect Scale to evaluate perfectionism.19.8% of crossfitters and 3.8% of gym members were at risk for exercise dependence. 11.7% of participants in the Crossfit group and 10% of participants in the control group had orthorexic symptoms. An association was found between the scores on the two behaviors. In addition, the dimension of perfectionism high standards predicted obligatory exercise and orthorexia nervosa, while the dimension of discrepancy predicted only exercise dependence.The study suggests that exercise dependence is more evident in Crossfit compared to gym athletes and may be accompanied by orthorexic symptoms. Orthorexia nervosa is a noticeable phenomenon in the population of active exercisers. Perfectionism is a risk factor for obligatory exercise and orthorexia. A more demanding selection of target populations is encouraged in order to better understand exercise dependence, orthorexia nervosa and their personality background.

Joint and muscle injuries in men and women CrossFit® training participants

OBJECTIVE

Verify the incidence and rate of joint and muscle injuries with the practice of CrossFit® and the potential risk factors for injuries in men and women.

METHODS

A total of 184 CrossFit® participants (97 men and 87 women). A questionnaire was conducted based on characterization, training routine, injuries, and additional information. The incidence refers to the number of new cases of injury in the sample during the CrossFit® training. The injury rate was calculated by estimating the number of weekly training hours and converted into the number of injuries per 1000 training hours.

RESULTS

Among the participants, 38.6% reported some type of injury, being joint injuries (83.1%) and/or muscle injuries (45.1%). The injury rate was 3.4/1000 h, with men having a higher rate. The location of the joint injuries was shoulders, wrists, and elbows, in addition to the lumbar spine in women. As for muscle injuries, the deltoid, upper back muscles, and quadriceps femoris were the most reported in men and deltoid, trapezius, upper back muscles, and gastrocnemius in women.

CONCLUSIONS

A better understanding of the anatomical distribution of the injuries may help coaches prescribe the most adequate workout that may reduce the likelihood of injuries occurring in CrossFit® training participants. It was demonstrated that gender, experience, weekly frequency, and previous injuries are important factors, and professionals must be concerned with the assessment of the participants and with an individualized progression in order to avoid risks.

Prevalence and factors associated with urinary incontinence in female crossfitters: A cross-sectional study

OBJECTIVE

To determine the prevalence and factors associated with urinary incontinence (UI) in female crossfitters.

METHODS

This is a cross-sectional study. Data were collected using assessment forms: Knowledge, Attitude and Practice survey for young female athletes; Incontinence Severity Index; and International Consultation on Incontinence Questionnaire for UI. Descriptive analysis was conducted to obtain absolute and relative frequencies, means and 95% confidence intervals (95% CI). Multivariate analysis was carried out to determine the association between UI and sociodemographic, gynecological-obstetric, and anthropometric variables, associated morbidities, previous history and physical activity.

RESULTS

Prevalence of UI, in the 189 included volunteers, was 38.6% and the most frequent type was stress UI (69.9%). A total of 72.6% of incontinent women reported urine loss during CrossFit training. Knowledge (53.4%) and attitude (86.2%) regarding UI were generally adequate, while prevention, management and treatment were inadequate (96.3%). The predominant characteristics of UI were frequency of once a week or less (74.0%), in small amounts (86.3%), mild intensity (57.5%) and slight impact on quality of life (64.3%). In multivariate analysis, no variable was significantly associated with UI.

CONCLUSIONS

The prevalence of UI in female crossfitters was 38.6%. The factors investigated did not contribute to the development of UI.

Prediction of Injuries in CrossFit Training: A Machine Learning Perspective

CrossFit has gained recognition and interest among physically active populations being one of the most popular and rapidly growing exercise regimens worldwide. Due to the intense and repetitive nature of CrossFit, concerns have been raised over the potential injury risks that are associated with its training including rhabdomyolysis and musculoskeletal injuries. However, identification of risk factors for predicting injuries in CrossFit athletes has been limited by the absence of relevant big epidemiological studies. The main purpose of this paper is the identification of risk factors and the development of machine learning-based models using ensemble learning that can predict CrossFit injuries. To accomplish the aforementioned targets, a survey-based epidemiological study was conducted in Greece to collect data on musculoskeletal injuries in CrossFit practitioners. A Machine Learning (ML) pipeline was then implemented that involved data pre-processing, feature selection and well-known ML models. The performance of the proposed ML models was assessed using a comprehensive cross validation mechanism whereas a discussion on the nature of the selected features is also provided. An area under the curve (AUC) of 77.93% was achieved by the best ML model using ensemble learning (Adaboost) on the group of six selected risk factors. The effectiveness of the proposed approach was evaluated in a comparative analysis with respect to numerous performance metrics including accuracy, sensitivity, specificity, AUC and confusion matrices to confirm its clinical relevance. The results are the basis for the development of reliable tools for the prediction of injuries in CrossFit.

Injury in CrossFit®: A Systematic Review of Epidemiology and Risk Factors

OBJECTIVE

To review the characteristics of the injuries among CrossFit® practitioners, including prevalence and incidence, nature, location, and risk factors.

METHODS

PubMed/MEDLINE, EMBASE, Web of Science, Scopus, and SPORTDiscus databases were searched from inception through August 2020, and English-language articles reporting on CrossFit®-related injuries were included. Data including sample (sex, age, and demographics) and injuries' characteristics (prevalence, incidence rate, nature, location, percentage of injuries requiring surgery and risk factors) were extracted.

RESULTS

Overall, twenty-five studies involving a total of 12,079 CrossFit® practitioners met the inclusion criteria. The mean prevalence of injuries among the included studies was 35.3%, with an incidence rate varying between 0.2 and 18.9 per 1000 hours of training. The most injured areas were shoulder (26%), spine (24%), and knee (18%). Among the studies that reported the injuries requiring surgery, the mean percentage was 8.7%. Regarding the risk factors associated with injuries, older age, male sex, a greater body mass index, the existence of previous injuries, the lack of coach supervision, the experience on CrossFit® and the participation in competitions were reported by the studies.

CONCLUSIONS

CrossFit® training has an injury incidence rate similar to weightlifting and powerlifting. Findings from the studies suggest that the most affected areas are shoulder, spine, and knee. The limited quality of the studies prevents us from drawing solid conclusions about injury risk factors.

Function, strength, and muscle activation of the shoulder complex in Crossfit practitioners with and without pain: a cross-sectional observational study

BACKGROUND

The shoulder joint is the most commonly injured joint in CrossFit practitioners, because of the high intensity and loads associated with this sport. Despite the large number of clinical cases, there is a shortage of studies that investigate influence of biomechanical aspects of upper limbs' injuries on CrossFit practitioners. This study hypothesized that there would be a difference in function, strength, and muscle activation between Crossfit practitioners with and without shoulder pain.

METHODS

We divided 79 Crossfit practitioners into two groups according to whether they reported pain (n = 29) or no pain (n = 50) in the shoulder during Crossfit training. Muscle function, strength, and activation were assessed using the Disability Arm, Shoulder and Hand function questionnaire, Upper Quarter Y Balance Test and Closed Kinetic Chain Upper Extremity Stability Test shoulder tests, isometric muscle strength assessment by manual dynamometry and muscle activation by surface electromyography and pain report.

RESULTS

The function based on questionnaire was associated with pain (p = 0.004). We observed a statistically significant difference between the two groups only in the surface electromyography activity of the lower trapezius, and in the variables of shoulder pain and function (p = 0.038).

CONCLUSION

Crossfit practitioners with shoulder pain occurring during training showed good function and stability of the shoulder joint, but there was a reduction in the activation of stabilizing muscles, especially the lower trapezius. Trial registration Registro Brasileiro de Ensaios Clinico (Brasilian National Registry) with the ID: RBR-2gycyv.

Disordered eating behaviors among CrossFit athletes

ABSTRACT Objective: Evaluate differences in disordered eating symptoms between men and women who practice CrossFit and to evaluate its predictors in this population. Methods: A cross-sectional study (April to June 2019) was carried out with 194 adults (103 women and 91 men) enrolled in private CrossFit boxes in Brazil, with a mean age of 30.19 years (SD = 5.34). Participants answered a sociodemographic questionnaire, the Eating Attitudes Test-26 (disordered eating), the Sociocultural Attitudes Towards Appearance Questionnaire-3 (body-ideal internalization), and the Drive for Muscularity Scale (drive for muscularity). A series of Student's t-tests was applied to test differences in disordered eating symptoms between men and women. Multiple linear regressions were conducted to evaluate predictors of disordered eating for both sexes. Results: Women showed greater disordered eating symptoms, dietary restrictions and excessive concern about thinness than men. Moreover, younger women with a higher BMI are more likely to have disordered eating symptoms. Higher drive for muscularity and greater general body-ideal internalization were also associated with disordered eating among women. In men, muscularity-oriented behavior was the only predictor of disordered eating. Conclusion: These findings are relevant, as they point out that women who practice CrossFit seem to be a high risk group for the development of eating disorders. In addition, muscularity-oriented behaviors in men and the drive for muscularity, internalization of the ideal body, BMI and age in women are predictors of disordered eating in CrossFit practitioners.

Incidence, severity and perceived susceptibility of COVID-19 in the UK CrossFit population

BACKGROUND

Contemporary literature indicates that a higher body mass index (BMI) serves as a risk factor for metabolic disease and is also correlated with greater disease severity. Subsequently, it has been linked to increased COVID-19 severity. The purpose of the study was to investigate whether regular CrossFit™ participation was associated with lower BMI, decreased COVID-19 severity and susceptibility.

METHODS

A cross-sectional study was conducted on 1806 CrossFit™ (CF) participants. Participants were asked about their age (yrs), sex (male vs. female), ethnic group, body height (cm) and weight (kg). Body mass index (BMI, kg/m2) was computed and consistent with WHO (2018) criteria. Participants self-reported their training history, health and lifestyle history, nutritional customs, present training status and suspected levels of exposure to COVID-19. Once submitted the collected data were coded, cleaned and analysed.

RESULTS

The final model comprised of 1806 CF individuals from an online survey response rate of 2086. The participants age ranged from 18 to 65+ yrs. Self-reported mean body mass index (BMI: kg/m2) reported that < 1% were underweight, 41% were healthy, 46% overweight, 10% class I obese, 2% class II obese, and < 1% class III obese. A Kruskal-Wallis H test compared gender and self-reported probability of being infected with COVID-19 with significant differences between subgroups (x2 (4, N = 1739) = 10.86, p = 0.03). Analysis of BMI and perceived severity of COVID-19 revealed a difference however not, significant (x2 (4, N = 1739) = 9.46, p = 0.051). Results on BMI and perceived probability of COVID-19 infection revealed no significant difference (x2 (4, N = 1739) = 2.68, p = 0.61). A separate analysis on BMI and perceived COVID-19 susceptibility revealed no significant difference (x2 (4, N = 1740) = 6.02, p = 0.20).

CONCLUSIONS

The purpose of the study was to establish whether habitual CrossFit™ participation is associated with reduced BMI, and to further investigate whether habitual participation impacted perceptions of disease. Results of the study indicate that self-reported CrossFit™ participation during the first UK lockdown, measured in minutes of exercise was indicative of a lower BMI. This has been associated with greater host immunity to disease. A history of CrossFit™ participation was not shown to impact perceptions of disease. However, our sample population reported few changes to habitual exercise during lockdown which may be due to the 'community' and increased adherence associated with CrossFit™.

An Analysis of Sport-Specific Pain Symptoms through Inter-Individual Training Differences in CrossFit

Background: CrossFit is one of the fastest growing “high-intensity functional training” methods in recent years. Due to the very demanding motion sequences and high loads, it was initially assumed that there was an extremely high risk of injury. However, studies have shown that injury rates are given between 0.74–3.3 per 1000 h of training, which is not higher than in other individual sports such as weightlifting. The purpose of the study was to estimate the type of pain symptoms that are directly related to CrossFit, to estimate the frequency of injuries that occur within a population of recreational CrossFit athletes, and, finally, to identify the factors influencing the frequency of pain during CrossFit training. Methods: A total of 414 active CrossFit athletes completed an online survey inclusive of 29 items focusing on individual physical characteristics and training behavior, as well as simultaneous or previously practiced sports. Results: There was a significantly higher proportion of knee pain in athletes who had previously or simultaneously played another sport (p = 0.014). The duration, intensity, or type of personal training plan developed, along with personal information such as age, gender, or BMI, had no significant influence on the pain data. We could not find any significant variance between the groups that we formed based on the differently stated one-repetition max (RMs). There were differences in athletes who stated that they did specific accessory exercises for small muscle groups. Above all, athletes performing exercises for the hamstrings and the gluteus medius indicated fewer pain symptoms for the sacro-iliac joint (SIJ)/iliac and lower back locations. Conclusions: It is important not to see CrossFit as a single type of sport. When treating a CrossFit athlete, care should be taken to address inter-individual differences. This underlines the significant differences of this study between the individual athletes with regard to the ability to master certain skills or their previous sporting experience. The mere fact of mastering certain exercises seems to lead to significantly more pain in certain regions. In addition, there seems to be a connection between the previous or simultaneous participation in other sports and the indication of pain in the knee region.

Correlation between previous sedentary lifestyle and CrossFit-related injuries

Objective:

To correlate CrossFit-related injuries with previous sedentary lifestyle, and to investigate other factors potentially associated with higher rates of injury among practitioners.

Methods:

A nationwide cross-sectional study involving CrossFit practitioners who received a digital questionnaire inquiring into CrossFit-related injuries, previous sedentary life, training intensity and experience, site of injury and general demographics.

Results:

This sample included 121 CrossFit practitioners, 34.7% of participants were sedentary prior to starting CrossFit practice, from these, 45.2% reported CrossFit-related injuries, compared to 30.4% from previously active practitioners (p=0.104). The shoulder/elbow (60.5%), lumbar spine (30.3%) and wrist/hand (16.3%) were the most common sites of injury among participants reporting CrossFit-related injuries (35.5%). Participants performing intense weight training were more prone to injuries than those practicing light or moderate weight training (p=0.043). On average, participants with a history of injury spent significantly more time training than those with no history of injury (68.4 and 61.7 minutes, respectively; p=0.044).

Conclusion:

The incidence of CrossFit-related injuries did not differ significantly between previously sedentary and physically active participants. Intense weight training was associated with a higher incidence of injuries. The overall injury rate was 35.5%, similar to that found in previous studies, and the most common site of injury was shoulder/elbow.

Injuries in functional fitness: an updated systematic review

INTRODUCTION

This study aimed to analyze injuries of functional fitness participants through a systematic review.

EVIDENCE ACQUISITION

A systematic search of the literature was conducted in CINAHL, EMBASE, PEDro, PubMed, SCOPUS, SPORTDiscus, and Web of Science, supplemented by searching in the grey literature, from 2017 to November 2020. This systematic review followed the PRISMA guidelines and was documented in the PROSPERO registry (CRD42020201259). Two reviewers independently extracted data including methodological (age, sex, time of practice, location, period, time frame, and completion rate) and injury (definition, diagnosis, prevalence, incidence, severity, mechanism, type, location, risk factors, and treatment) variables, as well as assessing study quality and risk of bias.

EVIDENCE SYNTHESIS

Twenty-six studies were included (10967, range 6-3049, participants). Injury was defined fairly differently across studies. The majority of studies used a retrospective study design and the main variables reported were prevalence, body location, and associated factors of injuries. The mean prevalence of musculoskeletal injuries was 32.8%, ranging from 2.4 to 60.6%, and the injury incidence per 1000 hours ranged from 0.21 to 67 36. The most affected body location in the studies was the shoulder, followed by lumbar spine, and knee. Muscle, joint, and ligament/tendon injuries were the most frequently reported. The majority of studies were of moderate methodological quality. All studies were considered as high risk of bias.

CONCLUSIONS

This review broadened the scope of 75 previous reviews on injuries in functional fitness. There have been few investigations regarding severity, mechanism, and treatment of injuries, so further research is warranted.

A Study on the Incidence of Hand or Wrist Injuries in CrossFit Athletes

Purpose

The purpose of this study was to investigate the reported rates and characteristics of injuries among CrossFit athletes with specific attention to the hand and wrist. We further sought to identify trends and associations of these injuries by examining demographic data.

Methods

A questionnaire was created to capture self-reported information on the incidence of hand or wrist injuries and their associations in CrossFit athletes. It was distributed between April 2020 and July 2020 to athletes training at CrossFit affiliated gyms in the New York and Pennsylvania regions. Bivariate logistic regression analysis was used to identify factors correlated with an injury.

Results

A total of 270 responses (97.5% response rate) were available for final analysis. The median age of respondents was 34 years and 72.2% had been participating in CrossFit for at least two years. CrossFit athletes reported injury rates of 62.2% while engaged in CrossFit training and 20.4% reported an injury specific to the hand or wrist. The majority of hand or wrist injuries occurred after one year of CrossFit training (65.4%). The majority of reported initial injuries occurred to the wrist (75.4%); subsequently, 29.1% reported reinjuring the same region. While 58.2% reported not yet having healed or taking longer than one month to feel fully healed, 72.8% reported returning to unmodified training within one month. Only 15 respondents reported seeking medical attention from a physician for their injury. Physicians generally recommended a training break of over one month, but only two patients reported taking a break this long. Male sex and length of participation in CrossFit were associated with an increased risk of developing a hand or wrist injury.

Discussion

Hand and wrist injuries represent a significant proportion of injuries among CrossFit athletes. CrossFit practitioners are potentially returning to unmodified training too early following injury, leaving them susceptible to further injury. Physicians and therapists must consider these findings and address both therapies and preventative measures for these types of injuries with their patients.

Acute Vertigo After CrossFit Workout in a Young Woman With Chiari I Malformation

CrossFit workout is associated with injuries mostly located over the spine and upper limb. Chiari I malformation (CIM) is characterized by migration of the cerebellar tonsils below the foramen magnum and this clinical condition has never been described after high-intense training such as CrossFit. A 19-year-old woman presented to the ED with acute vertigo, nausea, vomiting, and horizontal spontaneous nystagmus; symptoms began after an intense workout session. During neuro-otological examination, spontaneous positional left-beating horizontal nystagmus, normal response to bi-thermal caloric stimulations, and unremarkable cervical vestibular evoked myogenic potentials in both ears were observed; pure tone audiometry showed normal hearing. Central vertigo was suspected; therefore, an MRI was done, which identified a CIM. The patient's symptoms spontaneously improved at short term. The six-month follow-up MRI confirmed no changes. The subject completely stopped any training and remained asymptomatic over a 12-month follow-up. Our case report is the first describing CIM presented with acute vertigo after a high-intensity training.

Epidemiology and associated factors for CrossFit-related musculoskeletal injuries: a cross-sectional study

BACKGROUND

CrossFit® is usually composed of high intensity workout routines and is executed quickly, repetitively and with limited rest time. Previous studies have identified a high prevalence of injuries in CrossFit®. This study aimed to determine the prevalence of CrossFit-related musculoskeletal injuries and to identify potential associated factors.

METHODS

A cross-sectional study was conducted with 413 CrossFitters. Participants completed a questionnaire containing personal data, training characteristics and injury history in the last 12 months. Data were analyzed by descriptive statistics and logistic regression models.

RESULTS

The prevalence of CrossFit-related musculoskeletal injuries was 24.0%; and the injury rate was of 0.80 injuries per 1,000 hours of exposure. The regions of the body most affected were the lumbar spine (33.3%), shoulders (31.3%) and knees (14.1%). The majority of CrossFitters participated in competitions (74.6%), had more than 12 months of experience in CrossFit® (62.7%), and trained up to 90 minutes a day (82.3%) for more than 4 days a week (76.8%). The variables that showed a significant association with CrossFit®-related musculoskeletal injuries were weekly training frequency (OR=2.25; 95% CI: 1.13-4.48) and regular physiotherapeutic care (OR=1.85; 95% CI: 1.11-3.07).

CONCLUSIONS

The prevalence of musculoskeletal injury was 24.0%, and the most affected regions of the body were the lumbar spine, shoulders and knees. Training more than four days a week and do not receive regular physiotherapeutic care were associated with CrossFit-related musculoskeletal injuries.

Injury Incidence, Patterns, and Risk Factors in Functional Training Athletes in an Asian Population

Background

Functional training, also known as CrossFit, is a unique sport that combines weightlifting, gymnastics, and metabolic conditioning into a single program. There are an estimated 50 functional training centers in Malaysia.

Purpose

To analyze the injury rates, patterns, and risk factors of functional training/CrossFit.

Study Design

Descriptive epidemiology study.

Methods

Electronic questionnaires were distributed to 244 participants from 15 centers in the country. Descriptive data regarding the athletes, injury occurrence within the past 6 months, injury details, and risk factors were collected.

Results

Of the 244 athletes, 112 (46%) developed at least 1 new injury over the previous 6 months. Injury rates were significantly higher in athletes from nonaffiliate training gyms compared with CrossFit-affiliated gyms, in athletes with previous injuries, and in those who perceived themselves as having more than average fitness.

Conclusion

Coaches and athletes need to be more aware of risk factors for injury to enable safer and better training strategies.

CrossFit® – Development, Benefits and Risks

CrossFit is a form of high-intensity interval training and comparable to other high-intensity exercises. CrossFit exercises increase VO_2max, strength, endurance, and improves the body composition (e. g. lean body mass).

The injury risk in CrossFit is similar to that of other, comparable sports such as Olympic weightlifting, powerlifting and gymnastics and lower than that of competitive contact sports such as rugby union and rugby league. Shoulder joint, shoulder girdle and spine injuries are predominating in CrossFit and require special attention from physicians and coaches. In particular, this includes expert instruction for CrossFit beginners as well as an initial orthopedic examination before starting CrossFit training. The involvement of well-educated coaches correlates with a decreased injury rate. For this reason, it is recommended that beginners complete a special program with slow load increase and instructions of the fundamental CrossFit techniques. In CrossFit, previous injuries also increase the risk of re-injury, which is consistent with the findings of other sport-related injury studies, and should also be taken into account.

Evidence Level III

Breaking the myths of competition: a cross-sectional analysis of injuries among CrossFit trained participants

Objectives

The purpose of this study was to examine the injury rates of individuals engaged in CrossFit training and examine the risk of injury associated with competition.

Study design

Cross-sectional analysis.

Methods

Descriptive statistics, including injury incidence and rates, were examined for individuals reporting participation in a CrossFit sanctioned competition between 2013 and 2017. To examine the odds of being injured, we considered logistic regression models, where the primary independent measure was participation length—individual measures of interest included age, sex, body mass index, CrossFit affiliation and competition status.

Results

3049 individuals completed the survey (60% completion rate). All competitors, regardless of competition level, had similar incidence of injury (χ²=1.1, p=0.571). For those who reported competing, our calculated injury rate was 0.21–0.54 injuries per 1000 training hours, while for those not competing, the injury rate was calculated as 0.39–1.30 injuries per 1000 training hours. Logistic regression demonstrated short length of participation in CrossFit training as the main factor associated with the odds of being injured (OR=1.82; 95% CI: 1.15 to 2.92). Additionally, training at an official CrossFit affiliate appeared to have a protective effect from injury (OR=0.85; 95% CI: 0.65, 1.10).

Conclusion

Our findings provide evidence of the low risk of injury related to these events. Moreover, these findings support the notion that musculoskeletal injuries may be the result of poor progression plans, which may be minimised by participating in an official CrossFit affiliate.

Interquartile differences in biomechanical parameters in CrossFit® athletes during deep squats with submaximal load until fatigue

BACKGROUND

CrossFit^® exercises are demanding and require high power outputs sustained over time, therefore the daily workouts (WOD) could provoke considerable fatigue and lead to injury in a subsequent exercise session. To improve performance and prevent injury, the effect of pacing strategies has to be studied, by observing how fatigue modifies movement biodynamics until muscle failure. Thus, the present study aimed to analyze the interquartile differences in biomechanical parameters in CrossFit^® athletes during deep squats with submaximal load until fatigue.

METHODS

This is a comparative and descriptive applied research study using electromyographic analysis. Twenty CrossFit^® competition athletes participated in this study (age 27±6 years; training experience 14.4±7.7 months; weight 80±11 kg; height 175±7 cm; BMI 26±3 kg/m²).

RESULTS

The mean time until fatigue was 14±8 minutes. Pairwise comparisons confirmed fatigue by using the lactate results (pre=1.80 mg/dL, post=12.60 mg/dL; P=0.0001). Significant differences were noted among quartiles (Pillai's trace F=3.99; P=0.001) on the composite variable.

CONCLUSIONS

The results supported the hypothesis of self-regulation and showed higher velocity associated with higher maximal power. Concentric muscular recruitment was associated to the detriment of the eccentric phase during progressive fatigue. Coaches and athletes can apply the results of the present study when establishing WOD strategies during training and competition.

Injury risk and injury incidence rates in CrossFit

INTRODUCTION

Despite completing complex movements under cardiovascular and muscular fatigued conditions, CrossFit suggested safety of participants is one of the most important factors to consider. Therefore, the aim of this brief review was to provide an overview of the injury incidence and incidence rates reported in the current literature as well as to assess the injury risks associated with CrossFit.

EVIDENCE ACQUISITION

Research papers were searched using the following databases: Scopus, SPORTDiscus, Web of Science, PubMed, and MEDLINE. The search identified 718 potential articles across all databases. After the application of inclusion criteria, a total of 14 articles were included in this review.

EVIDENCE SYNTHESIS

The shoulder, spine, and knee are the most commonly injured areas in CrossFit. Injury incidence of each study ranges from 12.8-73.5% and reported injury rates ranging from 0.27-3.3/1000 training hours.

CONCLUSIONS

Reported findings in the current literature would suggest CrossFit has a relatively low injury risk. The current review highlights three important factors associated with injury incidence and incidence rates in CrossFit: 1) training frequency; 2) duration of CrossFit experience; 3) individuals that compete in CrossFit competitions. Due to recall bias and selection bias further research is warranted over a longitudinal prospective study. Additionally, further research is needed to investigate mechanisms of injury and the relationship between training load and injury risk in CrossFit.

CrossFit and the Epidemiology of Musculoskeletal Injuries: A Prospective 12-Week Cohort Study

Background:

Despite the increasing international popularity of CrossFit, there is a paucity of scientific evidence on the risk of CrossFit-related musculoskeletal injuries (CRMIs).

Purpose:

To investigate the incidence (cumulative incidence proportion [IP] and incidence density [ID]) of CRMIs and the association of CRMIs with personal and training characteristics.

Study Design:

Descriptive epidemiology study.

Methods:

A prospective, 12-week descriptive epidemiology cohort study was conducted in a convenience sample of CrossFit facilities in a single Brazilian city. Printed baseline questionnaires were distributed to 13 CrossFit boxes. All participants who filled out the questionnaire and consented to participate in the study were invited to respond to an online follow-up questionnaire every 2 weeks to collect data on CrossFit training characteristics and CRMIs. A CRMI was defined as any self-reported musculoskeletal injury or pain that prevented an athlete from exercising for at least 1 day. The IP was defined as the number of new cases divided by the entire population at risk, while the ID was defined as new events divided by the total person-time exposure in hours. Logistic mixed models were developed to investigate the association of CRMIs with personal and training characteristics.

Results:

A total of 515 CrossFit participants filled out the baseline questionnaire and provided informed consent, and 406 (78.8%) completed at least 1 follow-up measure. There were 133 participants who reported at least 1 CRMI during the study, and a total of 247 unique and new CRMIs were reported over a total estimated person-time exposure to CrossFit of 13,041 hours. The IP was 32.8% (95% CI, 28.4%-37.5%). The ID was 18.9 (95% CI, 16.6-21.3) per 1000 hours of CrossFit exposure. The shoulders (19.0%; n = 47) and lumbar spine (15.0%; n = 37) were most affected. Muscle injuries (45.3%; n = 112) and joint pain (24.7%; n = 61) were the most common CRMI types reported. Switching between prescribed and scaled down training loads (odds ratio [OR], 3.5 [95% CI, 1.7-7.3]) and previous injuries (OR, 3.2 [95% CI, 1.4-7.7]) were risk factors for a CRMI, while CrossFit experience was identified as a protective factor (OR, 0.7 [95% CI, 0.5-1.0]).

Conclusion:

In this 12-week prospective study, the ID was 18.9 CRMIs per 1000 hours of exposure; switching between training loads and previous injuries was associated with 3.5- and 3.2-fold higher odds, respectively, of sustaining CRMIs.

Part I: Crossfit-Related Injury Characteristics Presenting to Sports Medicine Clinic

OBJECTIVE

To investigate CrossFit-related injuries presenting to a pediatric sports medicine clinic.

DESIGN

Retrospective review of pediatric CrossFit-related injuries from between January 1, 2003, and June 31, 2016.

SETTING

Pediatric sports medicine clinic at a tertiary-level academic medical center.

PATIENTS

Patients with injury related to CrossFit participation.

INDEPENDENT VARIABLES

Sex, age, injury site, diagnosis, diagnostic imaging, and treatment.

MAIN OUTCOME MEASURES

Annual CrossFit-related injury proportion (%) over time.

RESULTS

One hundred fifteen medical identified (N = 55 female; mean age, 25.2 ± 10.4 years). Proportion of CrossFit-related injuries presenting to clinic relative to overall clinic volume consistently increased over time (Pearson r = 0.825; P = 0.022). Injury location included head (0.08%), trunk/spine (25.2%), upper extremity (27.0%), and lower extremity (47.0%). Common injured joints included knee (27%), spine (24.3%), and shoulder (16.5%). Nearly half of patients had a single diagnostic imaging (49.6%; 57 of 115). Most common diagnostics included magnetic resonance imaging (60.0%; 69 of 115), plain radiographs (51.3%; 59 of 115), ultrasound (10.4%; 12 of 115), and computerized tomographic scan (9.6%; 11 of 115). Most commonly prescribed treatments included physical/occupational therapy (38.3%; 44 of 115), activity modification (19.1%; 22 of 115), crutches/brace/splinting/compression sleeve (13.0%; 15 of 115), and non-steroidal anti-inflammatory medications (10.4%; 12 of 115).

CONCLUSIONS

CrossFit-related injury proportion presenting to a pediatric sports medicine clinic increased over time. A notable proportion of injuries occurred to the trunk and spine. Advanced imaging was obtained in approximately half of these youth athletes. Further research in youth CrossFit athletes is required surrounding mechanism of injury to prevent future injury in this mode of training for youth athletes.

Injuries in Novice Participants during an Eight-Week Start up CrossFit Program-A Prospective Cohort Study

Background: Previously published studies have reported injury rates ranging from 0.74 to 3.3 per 1000 h of exposure in CrossFit participants. However, the existing body of evidence is mainly based on experienced participants; therefore, the injury incidence and injury rate within novice CrossFit participants remains relatively unknown. The aim of this study wasto investigate the injury incidence and injury rate among novice participants in an eight-week CrossFit program. Methods: This survey-based prospective cohort study included CrossFit Copenhagen’s novice members who began an eight-week, free-of-charge membership period. A questionnaire was distributed at baseline and at eight-week follow-up. Information about exposure was retrieved through the online booking system. Injury incidence, defined as proportion of participants who sustained an injury, and injury rates per 1000 h of exposure were calculated. Results: Among the 168 included participants, a total of 28 injuries (14.9%) were reported. The number of injured participants and total exposure time resulted in an injury rate per 1000 h of exposure of 9.5. Conclusions: Compared to the existing body of evidence, the findings in this study indicate that the risk of injuries is higher among novice participants than among experienced CrossFit participants.

Identifying the Most Common CrossFit Injuries in a Variety of Athletes

Background

CrossFit is an increasingly popular, rapidly growing exercise regimen. Few studies have evaluated CrossFit-associated musculoskeletal injuries on a large scale. This study explores such injuries and associated risk factors in detail.

Objective

To identify the most common musculoskeletal injuries endured during CrossFit training among athletes at different levels of expertise.

Design

Survey-based retrospective cross-sectional study.

Setting

Distribution at CrossFit gyms in the United States and internationally. Also published on active online forums.

Participants

A total of 885 former and current CrossFit athletes.

Methods

Institutional review board-approved 33-question Web-based survey focused on CrossFit injuries and associated risk factors. Survey submissions were accepted for a period of 6 months.

Main outcome measurements

Specific injuries with associated workouts, risk factors that affected injury including (1) basic demographics, (2) regional differences in reported injuries, (3) training intensity, and (4) expertise level at time of injury.

Results

Of the 885 respondents, 295 (33.3%) were injured. The most common injuries involved the back (95/295, 32.2%) and shoulder (61/295, 20.7%). The most common exercises that caused injury were squats (65/295, 22.0%) and deadlifts (53/295, 18.0%). Advanced-level (64/295, 21.7%) athletes were more significantly injured than beginner-level (40/295, 13.6%) athletes. International participants were 2.2 times more likely than domestic US participants to suffer injury. Individuals with 3+ years of CrossFit experience were 3.3 times more likely to be injured than those with 2 or less years of experience. Participants who trained for 11+ h/week were significantly more likely to be injured than those who trained less than or equal to 10 h/week.

Conclusions

As CrossFit becomes more popular, it is important to monitor the safety of its practitioners. Further studies are needed to explore how to lower this injury prevalence of 33.3%. Areas to focus on include factors that have caused the regional (international vs US states) differences, level of expertise/experience differences (advanced level vs intermediate and beginner levels), and stretching routine modifications.

Assessment and validation of a Spanish version of the Muscle Dysmorphia Disorder Inventory in Argentinian men who exercise: Inventario de Dismorfia Muscular

Despite an increase in body dissatisfaction and muscularity concerns among Latin American men, there is a paucity of research relating to muscle dysmorphia in this population. In this study we aimed to evaluate, for the first time in Latin America, the factor structure of the Muscle Dysmorphic Disorder Inventory (MDDI; Hildebrandt, Langenbucher, & Schlundt, 2004). A sample of 551 men who exercise completed measures of body dissatisfaction, disordered eating, and the MDDI. Exploratory factor analysis in a first split-half sample revealed a 3-factor solution similar to the original version, which was then tested through confirmatory factor analysis (CFA) in a second split-half sample. A re-specified model (allowing for error correlations between Items 10-13 and 11-13) presented adequate fit. Omega coefficients revealed adequate internal consistency (> .80) for the Drive for Size and Functional Impairment subscales. The internal consistency for the Appearance Intolerance subscale was .74 and .72 across subset samples. Associations with body dissatisfaction, disordered eating, body mass index, and frequency of training and rest days are presented as evidence of construct validity. Finally, multi-group CFA indicated that the model was invariant across type of exercise. Overall, these data suggest that the MDDI is suitable for use in Spanish-speaking Latin American male populations.

Verbal Encouragement and Between-Day Reliability During High-Intensity Functional Strength and Endurance Performance Testing

As verbal encouragement (VE) is used in high intensity functional exercise testing, this randomized controlled crossover study aimed at investigating whether VE affects high intensity functional strength and endurance performance testing. We further examined between-day variability of high intensity functional strength and endurance performance testing with and without VE. Nineteen experienced athletes (seven females and 12 males, age: 23.7 ± 4.3 years) performed a standardized one repetition maximum (1 RM) squat test and a 12-min high-intensity functional training (HIFT) workout [as many repetitions as possible (AMRAP)] on four different days over a 2-week period. Athletes randomly performed each test twice, either with VE or without (CON), with a minimum of 72 h rest between tests. Very good to excellent relative between-day reliability with slightly better values for strength testing (ICC: 0.99; CV: 3.5–4.1%) compared to endurance testing (ICC 0.87–0.95; CV: 3.9–7.3%) were observed. Interestingly, VE led to higher reliability during endurance testing. Mean squat strength depicted higher strength values with VE (107 ± 33 kg) compared to CON (105 ± 33 kg; p = 0.009, Cohen’s d: 0.06). AMRAP in the endurance test showed negligible differences between VE (182 ± 33 AMRAP) and CON (181 ± 35 AMRAP; p = 0.71, Cohen’s d: 0.03). In conclusion, the effects of VE do not notably exceed day-to-day variability during high intensity functional strength (CV: 3.5–4.1%) and endurance (CV: 3.9–7.3%) testing. However, high intensity functional strength and endurance testing with VE seems to be slightly more reliable, particularly during endurance testing.

CrossFit®: Injury prevalence and main risk factors

OBJECTIVES

This study sought to determine prevalences of injuries associated with CrossFit® training and assess profiles of these injuries and the affected athletes.

METHODS

Data were collected over a 12-month period using a questionnaire administered directly to practitioners at CrossFit®-affiliated fitness centers in the state of São Paulo, Brazil. Of the 414 participants, 157 (37.9%) participants reported having suffered an injury while practicing CrossFit®.

RESULTS

The injury rate was 3.24 injuries per 1,000 hours of training. The probability of injury for athletes who had practiced CrossFit® for longer than 12 months was 82.2%, which was higher than the corresponding probability for beginner athletes. The probability of injury was 5-fold higher among competitive-level athletes than that among less-experienced athletes. No evidence of an association between the occurrence of injuries during CrossFit® practice and any of the following athlete characteristics was found: age, gender, practice of other sports, weight, and height. The incidence of injuries in this sports modality was similar to that in other modalities, including Olympic weight lifting (OWL), basic weight lifting, and artistic gymnastics.

CONCLUSION

CrossFit® appears to be a training program that is suitable for different age groups when performed in a safe environment and with assistance from qualified professionals.

Are extreme conditioning programmes effective and safe? A narrative review of high-intensity functional training methods research paradigms and findings

Extreme conditioning programmes (ECPs, eg, CrossFit, Insanity and Gym Jones) are a growing fitness regimen characterised by functional movements performed at high-intensity and with constantly varying movements. While the popularity and number of practitioners of ECPs are growing, a debate has been established between what is observed in the scientific literature and anecdotal reports from athletes, coaches and physicians about safety (incidence and prevalence of injuries and rhabdomyolysis) and benefits (physical and mental health). In this article, we review the prevalence and incidence of injuries, rhabdomyolysis, physiological responses and chronic adaptations to ECPs. The majority of the available evidence confirm that the estimated injury rate among athletes participating in ECPs is similar to that in weightlifting and most other recreational activities. Additionally, ECP sessions resulted in increased acute oxidative, metabolic and cardiovascular stress, and depending on the stimulus (intensity, duration and non-usual exercise) and training status of the practitioner, an ECP session may precipitate rhabdomyolysis. In the scientific literature, the current chronic effects of ECPs showed little or no effects on body composition and improvements in physical fitness and psychological parameters; however, further studies are important.

A 4-Year Analysis of the Incidence of Injuries Among CrossFit-Trained Participants

Background:

High-intensity functional training (HIFT) is a new training modality that merges high-intensity exercise with functional (multijoint) movements. Even though others exist, CrossFit training has emerged as the most common form of HIFT. Recently, several reports have linked CrossFit training to severe injuries and/or life-threatening conditions, such as rhabdomyolysis. Empirical evidence regarding the safety of this training modality is currently limited.

Purpose:

To examine the incidence of injuries related to CrossFit participation and to estimate the rate of injuries in a large cross-sectional convenience sample of CrossFit participants from around the world.

Study Design:

Descriptive epidemiology study.

Methods:

A total of 3049 participants who reported engaging in CrossFit training between 2013 and 2017 were surveyed.

Results:

A portion (30.5%) of the participants surveyed reported experiencing an injury over the previous 12 months because of their participation in CrossFit training. Injuries to the shoulders (39%), back (36%), knees (15%), elbows (12%), and wrists (11%) were most common for both male and female participants. The greatest number of injuries occurred among those who participated in CrossFit training 3 to 5 days per week (χ² = 12.51; P = .0019). Overall, and based on the assumed maximum number of workout hours per week, the injury rate was 0.27 per 1000 hours (females: 0.28; males: 0.26), whereas the assumed minimum number of workout hours per week resulted in an injury rate of 0.74 per 1000 hours (females: 0.78; males: 0.70).

Conclusion:

Our findings suggest that CrossFit training is relatively safe compared with more traditional training modalities. However, it seems that those within their first year of training as well as those who engage in this training modality less than 3 days per week and/or participate in less than 3 workouts per week are at a greater risk for injuries.

Comparing forward and backward chaining in teaching Olympic weightlifting

The popularity of Olympic-style weightlifting in fitness routines is growing, but participating in these exercises with improper technique places lifters at increased risk for injury. Fitness training professionals have developed multiple teaching strategies, but have not subjected these strategies to systematic evaluation, particularly with novice lifters. Two strategies recommended by professional training organizations are akin to forward and backward chaining, which have been shown effective at teaching other novel, complex behaviors. The present study compared these forward- and backward-chaining-like strategies to teach novice lifters "the clean" and "the snatch," two Olympic weightlifting movements frequently incorporated into high-intensity training programs. Participants performed lifts taught with forward chaining more accurately than lifts taught with backward chaining.

Perfil de lesões em praticantes de CrossFit: revisão sistemática

RESUMO O CrossFit se apresenta como um novo método de treinamento físico que vem ganhando popularidade desde sua criação. O objetivo deste estudo foi analisar o perfil de lesões em praticantes de CrossFit por meio de uma revisão sistemática da literatura. Utilizaram-se as recomendações da Declaração PRISMA para condução da revisão sistemática. A busca foi realizada nas bases de dados CINAHL, SciELO, Science Direct, SCOPUS, LILACS, PEDro, PubMed, SPORTDiscus e Web of Science. Avaliou-se a qualidade metodológica dos estudos, entre os quais dez foram considerados elegíveis. A prevalência de lesões nos praticantes de CrossFit variou de 5 a 73,5%, e a taxa de lesão variou de 1,94 a 3,1 lesões a cada 1.000 horas de treinamento. A região corporal mais acometida por lesões nos estudos selecionados foram os ombros, seguidos pelas costas e joelhos. Em relação aos fatores associados às lesões, destacou-se o tipo de exercício realizado e o tempo de prática de CrossFit. O sexo apresentou associação com a prevalência de lesões, estudos demonstraram que os homens apresentaram maior número de lesões em relação às mulheres. A idade esteve entre os fatores que não estiveram associados às lesões. Conclui-se que os ombros são a região corporal mais comumente acometida entre os praticantes de CrossFit, em indivíduos do sexo masculino e com lesões prévias, muitas vezes obtidas em outras modalidades. Ainda, que o CrossFit pode ser praticado com segurança por indivíduos de 18 a 69 anos.