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

From Sweat to Strain: An Epidemiological Analysis of Training-Related Injuries in CrossFit®

Purpose

This study aims to conduct an epidemiological investigation into the types and causes of injuries during CrossFit® training in Germany.

Patients and Methods

Voluntary athletes from various German CrossFit® gyms participated, providing personal information, training habits, and details on injuries through a standardized questionnaire.

Results

The study involved 308 participants, with an equal sex split, a peak age of 20-40, and a BMI of 24.3 ± 3.3 kg/m2. Most participants trained for over two years (49.4%), primarily in supervised groups. Motivations for engaging in CrossFit® included health prevention (33.1%), athletic training (32.8%), and work-life balance support (17%). Injuries were reported by 28.6% of participants, with 61.4% experiencing single injuries. The majority of injuries (55.3%) occurred during the middle of workouts. Injury types included wounds (23.3%), contusions, sprains, or strains (cumulative 30.8%), and fractures (2.9%). Almost all injured individuals (96.5%) had a time-loss injury, with a return to sport ranging from a day to over three months. Treatments varied, with 50.6% not requiring medical intervention, 34.1% undergoing physiotherapy, 21.2% receiving medication and 8.2% needing surgery. Barbell exercises, notably Snatch and Clean, were main exercises with association to injuries, accounting for 36.3%. The Box Jump stood out as the exercise with the highest isolated injury prevalence (14.3%). Notable injury causes included falls during Pull-Ups and lumbar disc herniation linked to Deadlifts. Following injuries, 45.8% of participants made training adjustments.

Conclusion

This study provides an epidemiological investigation into the types and causes of injuries during CrossFit® training in Germany. The shoulder and knee joint exhibited the highest injury prevalence. Barbell exercises, box jumps, and bar pull-ups were identified as major exercises with association to injuries. Prevention through technical training and the incorporation of soft boxes could reduce the risk of injuries in CrossFit®.

Prevalence and predictors of musculoskeletal injuries among gym members in Bangladesh: A nationwide cross-sectional study

BACKGROUND

Participating in physical exercise is advantageous for maintaining optimum health, improving physical capacity, decreasing the likelihood of chronic diseases, and promoting overall wellbeing.

AIM

This study aimed to find out the prevalence and factors that contribute to musculoskeletal injuries among individuals who participated in fitness activities at the gym.

METHODS

This cross-sectional study included 1123 gym members, both male and female, aged between 18 and 50 years, from selected fitness centers in Bangladesh. Musculoskeletal injuries were assessed using the Nordic musculoskeletal disorder questionnaire. Binary logistic regression identified the gym members' predictors of musculoskeletal injuries.

RESULTS

The highest prevalence of musculoskeletal injuries at the low back (36.6%) was seen among the eight body sites, followed by the shoulder (24.7%) and knee (17.1%). Males (aOR 2.589, CI 1.18 to 5.65) and those who go to the gym to lose weight (aOR 3.859, CI 0.91 to 16.33) and for physical fitness (aOR 1.895, CI 1.07 to 3.35) had a greater risk of musculoskeletal injury. Participants who carried out strength training exercises (aOR 4.10, CI 2.74 to 6.19) had a four-fold increased risk of musculoskeletal injuries than those who did not. Furthermore, higher adjusted odds of musculoskeletal injuries were found for the potential causes of injuries in incorrect holding (aOR 1.69, CI 1.10 to 2.60), overweight lifting (aOR 2.00, CI 1.30 to 3.08), lack of workout knowledge (aOR 3.56, CI 2.09 to 5.85), and insufficient information from the trainer (aOR 5.66, CI 1.84 to 17.39).

CONCLUSION

Musculoskeletal injuries are highly prevalent among gym-goers in Bangladesh. The back was the most often injured area, followed by the shoulder and knee. It is important to exhibit caution and take extra care while doing strength training activities in order to avoid injury. Prior to engaging in gym-based activities, it is essential to have a thorough understanding of proper exercise knowledge.

Effectiveness of Percutaneous Needle Electrolysis to Reduce Pain in Tendinopathies: A Systematic Review With Meta-Analysis

CONTEXT

Tendon injuries are common disorders in both workers and athletes, potentially impacting performance in both conditions. This is why the search for effective treatments is continuing.

OBJECTIVE(S)

The objective of this study was to analyze whether the ultrasound-guided percutaneous needle electrolysis technique may be considered a procedure to reduce pain caused by tendinosis.

EVIDENCE ACQUISITION

The search strategy included the PubMed, SCOPUS, CINAHL, Physiotherapy Evidence Database, SciELO, and ScienceDirect up to the date of February 25, 2024. Randomized clinical trials that assessed pain caused by tendinosis using the Visual Analog Scale and Numeric Rating Scale were included. The studies were evaluated for quality using the Cochrane Risk of Bias 2, and the evidence strength was assessed by the GRADEpro GDT.

EVIDENCE SYNTHESIS

Out of the 534 studies found, 8 were included in the review. A random-effects meta-analysis and standardized mean differences (SMD) were conducted. The ultrasound-guided percutaneous needle electrolysis proved to be effective in reducing pain caused by tendinosis in the overall outcome (SMD = -0.97; 95% CI, -1.26 to -0.68; I2 = 58%; low certainty of evidence) and in the short-term (SMD = -0.83, 95% CI, -1.29 to -0.38; I2 = 65%; low certainty of evidence), midterm (SMD = -1.28; 95% CI, -1.65 to -0.91; I2 = 0%; moderate certainty of evidence), and long-term (SMD = -0.94; 95% CI, -1.62 to -0.26; I2 = 71%; low certainty of evidence) subgroups.

CONCLUSION(S)

The application of the ultrasound-guided percutaneous needle electrolysis technique for reducing pain caused by tendinosis appears to be effective. However, due to the heterogeneity found (partially explained), more studies are needed to define the appropriate dosimetry, specific populations that may benefit more from the technique, and possible adverse events.

Functional capacity and risk of injury in CrossFit practitioners measured through smartphone apps

BACKGROUND

CrossFit is a high intensity functional training that tends to challenge physical limits. The objectives of this study were to assess functional capacity, prevalence and risk of injury in CrossFit practitioners.

METHODS

This cross-sectional, observational and prospective study evaluate the rate of injuries that occurred in CrossFit practitioners in the last 12 months and their functional capacities. The sample was given for convenience, with a total of 22 participants. Functional capacities and risk of injury were measured by functional tests using PHAST and Clinometer applications. The prevalence of injuries was cataloged using the Nordic Musculoskeletal Questionnaire.

RESULTS

5% of the injuries occurred in the neck; 9% in shoulder, hip, thighs, ankles and feet; 14% in the lumbar spine and knees. The worst functional results were for the shoulder medial rotation ROM test, where 86-95% of the athletes were classified as "Bad"; the dorsiflexion ROM test also performed poorly in 68% of athletes.

CONCLUSION

This study shows that the CrossFit practice suggests that the injury prevalence is relatively low, affecting mainly knees, lumbar spine, wrists and hands. However, the risk of injuries shown by the functional musculoskeletal assessment is higher, especially in the shoulder and ankle, and it is important for the practitioner to realize a specific functional assessment before starting training.

Standardized vs. Relative Intensity in CrossFit

CrossFit is characterized by being a standardized training program that improves physical performance through the provision of several stimuli regardless of the participant's strength level. This study aimed to compare the acute response in total repetitions as a measurement of performance, jump ability, physiological demand (heart rate and blood lactate), and perceived effort considering the participants' strength level with individualized intensity in CrossFit. Thirty-five participants were assessed and asked to participate on two separate days in a standardized and relative 'As Many Repetitions As Possible' (AMRAP) CrossFit circuit. Both AMRAPs comprised strength, gymnastic and aerobic exercises, although only strength was individualized according to the participant's level. Before the statistical analysis, participants were allocated to higher- or lower-strength groups following the one-repetition maximum-bodyweight ratio in the push press exercise. Results support the existence of a strong relationship between strength level and total repetitions in both AMRAPs. In addition, differences in total repetitions and rate of perceived exertion between strength groups are discarded when AMRAP intensity is individualized while physiological demand and jump ability are maintained. Thus, the higher-strength participants may benefit from similar responses with a lower number of repetitions. Therefore, CrossFit trainers should be encouraged to prescribe strength tasks based on the percentage of 1RM for every training.

Trunk muscles influence lower limb performance in crossfit athletes: A cross-sectional study

INTRODUCTION

Crossfit is a sport that combines cardio-respiratory and muscle endurance, strength, flexibility, muscle power, speed, coordination, agility and balance. However, there is no information in the literature regarding functional performance of the lower limbs and the endurance of core muscles in this population. The objective of this study was to evaluate the correlation between trunk strength/endurance and lower limb function through lower limb symmetry and balance tests.

METHODS

Forty-one young adults aged 19-41 years (26.3 ± 5.4) participated, 15 sedentary and 26 cross fit practitioners for at least one year. The tests were as follows: Biering-Sørensen Test of trunk extensor endurance, Trunk Flexors Endurance Test at 60°, Side Plank Endurance Test, Lumbar Dynamometry, Single-Leg Hop Test and Star Excursion Balance Test.

RESULTS AND DISCUSSION

Although there were higher values, there was no significant difference (p > 0.05) between the groups for lower limb symmetry and strength of trunk flexor muscles. For balance, strength and resistance variables of trunk extensor muscles, the values found were higher in crossfit practitioners than in sedentary subjects.

CONCLUSION

There is a relationship between trunk muscle strength and endurance and lower limb balance. Moreover, cross fit athletes showed higher values of trunk muscle strength/endurance and lower limb balance compared to sedentary adults.

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.

Spinal Muscle Thickness and Activation during Abdominal Hollowing and Bracing in CrossFit® Athletes

Exercises that improve muscle activation are essential for maintaining spinal stability and preventing low back pain. The purpose of this study was to compare the effects of abdominal hollowing and bracing on the activation of the core muscles in CrossFit® participants using ultrasound and electromyography (EMG). Twenty-four healthy adults aged 21 to 42 years old with at least two years of CrossFit® experience performed three core stability exercises (plank, side plank, bridge) with abdominal hollowing and bracing. We measured the ultrasound relative thickness of the local core muscles (transversus abdominis, internal oblique, and lumbar multifidus), and the EMG percentage of maximal voluntary contraction (MVC) of the global core muscles (rectus abdominis, external oblique, and iliocostalis lumborum). Analysis of variance tests showed that the relative thickness of the local core muscles was greater (p = 0.016) during hollowing (range from 26.8 ± 5.33 to 88.4 ± 11.9% of rest) than bracing (range from 15.9 ± 3.54 to 61.2 ± 15.9% of rest), while the EMG of the global muscles was greater (p = 0.001) in bracing (range from 24.4 ± 7.30 to 72.5 ± 9.17% of MVC) than hollowing (range from 16.4 ± 3.70 to 56.6 ± 7.65% of MVC). These results indicate that the recruitment of spinal muscles during popular exercises is achieved with both hollowing and bracing. Nevertheless, it appears that hollowing tends to recruit more of the local muscles, whilst bracing recruits more of the global muscles. The grading of the exercises varied between muscles and varied between maneuvers, especially for the surface abdominals and lumbar muscles. CrossFit® practitioners can choose to use either hollowing or bracing to activate their core muscles more selectively or more appropriately, depending on the goal and purpose of the exercise.

Trunk, Mass Grasp, Knee, and Hip Muscle Performance in CrossFit Participants: Reference Values According to Participants' Sex and Limb Dominance

Background

CrossFit is characterized by a diverse range of exercises recruiting different muscles and requiring different muscle functions. A characterization of muscular performance parameters in this population is needed.

Purpose

To determine reference values for various aspects of muscular performance of muscles of the trunk, thigh, hip, and mass grasp in CrossFit participants. Also, this investigation aimed to compare the strength measures between male and female CrossFit participants, as well as between dominant and non-dominant limbs.

Design

Descriptive, Cross-sectional.

Setting

Laboratory.

Methods

Isometric strength of trunk extensors (TE) and mass grasp was measured with handheld and Jamar dynamometer respectively. An isokinetic dynamometer was used to assess the muscle performance of the knee flexors (KF) and extensors (KE) (at 60º/s and 300º/s), and hip flexors (HF), extensors (HE), and abductors (HA) (60º/s and 240º/s ). Reference values for torque, work, power, fatigue, flexor:extensor ratio for the knee (hamstring:quadriceps - H:Q) and hip (HF:HE) joints were calculated. The torque and work values were normalized by the body mass. Mixed multivariate and univariate analyses of variance and independent t-tests were used for statistical analyses to compare between sexes and limbs.

Results

Participants included 111 individuals (58 males and 53 females) with at least one year of experience in CrossFit. Normative data are provided for the outcome variables. Males had greater values of muscular performance parameters than females in most variables (p<0.05). Also, the dominant limb had greater mass grasp strength (p<0.002), greater KE power at 60º/s (p=0.015), lower H:Q ratio at 60º/s (p=0.021) and 300º/s (p=0.008), and lower KE fatigue (p=0.002).

Conclusion

This study provides reference values for the trunk extensors, mass grasp, knee, and hip muscle performance in male and female CrossFit practitioners. Their muscle performance profile was characterized by few inter-limb asymmetries, and males demonstrated greater muscular performance outcomes than females, even after normalization by body mass. These reference values can be used for comparisons in research and clinical settings.

Level of Evidence

3b.

How Do Fitness Club Members Differentiate in Background Characteristics, Exercise Motivation, and Social Support? A Cross-Sectional Study

Fitness clubs are one of the largest exercise arenas worldwide. Still, membership withdrawal and exercise dropout rates are 40-65% in the first six months. One important approach to retaining members may be to create an environment that feels inclusive, and clusters members with mutual needs and interests. Increased knowledge in this field can provide valuable information that leads to more effective exercise promotion strategies and better retention rates, important to the long-term success of the gym and public health. Thus, we aimed to compare background factors, motivation, and social support between members of multipurpose (wide range of exercise concepts/facilities, middle to high membership fee), fitness-only (low membership fee), and boutique (one or two specialized exercise concepts, high membership fee) fitness clubs. A total of 232 members from multipurpose (n = 107), fitness-only (n = 52), and boutique gyms (n = 73) were recruited for this cross-sectional study. Data included background variables (age, gender, body weight and height, smoking, total household income, occupation, education, and general health), exercise behaviour, exercise motivation, and social support. A one-way between-group ANOVA with Bonferroni correction or a chi-square test was used as appropriate. Multipurpose and fitness-only members were older (mean diff: 9.1 years, p = <0.001) and exercised less (mean diff: 1-1.2 sessions/week, p = <0.001) than members from boutique clubs. Compared with multipurpose and fitness-only members, members from boutique clubs reported the highest autonomous motivation (intrinsic regulation: mean diff: 0.3, p = 0.030), and perceived greater social support from family/friends (mean diff: 6.4 to 6.6, p = <0.001). Boutique members were younger, exercised more, and reported higher autonomous motivation and social support than multipurpose and fitness-only members. Our results suggest that exercise enjoyment and a social community, the "philosophy" of boutique gyms, may be important for regular exercise.

CrossFit®: 'Unknowable' or Predictable?-A Systematic Review on Predictors of CrossFit® Performance

The functional fitness training program CrossFit^® is experiencing fast-growing and widespread popularity with day-to-day varying 'Workouts of the Day' (WOD). Even among tactical athletes, the training program is widely applied. Nevertheless, there is a lack of data on which parameters influence CrossFit^® performance. For this reason, the purpose of this study is to conduct a systematic review of the existing literature to identify and summarize predictors of CrossFit^® performance and performance enhancement. In accordance with the PRISMA guidelines, a systematic search of the following databases was conducted in April 2022: PubMed, SPORTDiscus, Scopus, and Web of Science. Using the keyword 'CrossFit', 1264 entries are found, and 21 articles are included based on the eligibility criteria. In summary, the studies show conflicting results, and no specific key parameter was found that predicts CrossFit^® performance regardless of the type of WOD. In detail, the findings indicate that physiological parameters (in particular, body composition) and high-level competitive experience have a more consistent influence than specific performance variables. Nevertheless, in one-third of the studies, high total body strength (i.e., CrossFit^® Total performance) and trunk strength (i.e., back squat performance) correlate with higher workout scores. For the first time, this review presents a summary of performance determinants in CrossFit^®. From this, a guiding principle for training strategies may be derived, suggesting that a focus on body composition, body strength, and competition experience may be recommended for CrossFit^® performance prediction and performance enhancement.

Musculoskeletal Injuries and Risk Factors in Spanish CrossFit® Practitioners

CrossFit^® Training is a physical and sports-conditioning system based on constantly varied functional movements performed at high intensity. CrossFit^® has been shown to significantly improve general physical performance and body composition. Although there seems to be an association between the practice of CrossFit^® and musculoskeletal injuries, the relationship between CrossFit^® and injury risks has been poorly studied. The main objective of this study was to establish the relationship between CrossFit^® and musculoskeletal injuries. Secondary objectives were the analysis of various risk factors and injury and the comparison of the incidence of CrossFit^® injuries to that of other sports. An online questionnaire was distributed to gyms affiliated with CrossFit^®, Inc. in the Principality of Asturias, Spain in order to carry out a retrospective transversal descriptive study. The frequency of injuries in CrossFit^® is similar to most sports. Injuries are often minor and of short duration, with the shoulder being the most affected joint complex.

Humeral Fracture in a Young CrossFit Practitioner

CrossFit (CrossFit Inc, Washington, DC) is a recent, high-intensity strength and conditioning sport that is growing in popularity worldwide. Potential risks and injuries have been described in previous reports. Distal humeral fractures without direct trauma were related to sports like baseball or wrestling. However, they have never been reported in a CrossFit athlete. We present the first case of distal humeral fracture associated with a CrossFit workout, during a gymnastic movement. Our patient had no relevant medical history but the investigation revealed reduced vitamin D levels and low bone density. The patient was surgically treated and he completed the rehabilitation program. He returned to sports practice 12 weeks after the surgery.

Using Wearable Inertial Sensors to Monitor Effectiveness of Different Types of Customized Orthoses during CrossFit® Training

BACKGROUND

Dynamic balance plays a key role in high-impact sports, such as CrossFit, where athletes are required to maintain balance in various weightlifting exercises. The loss of balance in these sport-specific movements may not only affect athlete performance, but also increase the risk of injuries.

OBJECTIVES

The aim of the study is to achieve greater insight into the balance and athlete position during the CrossFit training by means of inertial sensors, with a particular focus on the role of different custom foot orthoses (CFOs) in order to detect correlations with the role of the cavus foot.

METHODS

A total of 42 CrossFit^® athletes, aged 25 to 42 years, were enrolled in this study. One-way ANOVA tests with post-hoc analysis of variance were used to compare foot posture groups and effects of different types of customized foot orthoses.

RESULTS

When comparing the effects of CFOs with the respective balance basal level during the pistol squat exercise, we observed a significant (p = 0.0001) decrease in the sway area, antero-posterior displacement (APD) and medio-lateral displacement (MLD) compared to the basal using both types of CFOs.

CONCLUSION

No significant positive effects of CFOs were observed in some static tests. On the contrary, positive effects of CFOs and, in particular, postural insoles, are relevant to dynamic balance.

Risk Factors for Injury in CrossFit®-A Retrospective Analysis

CrossFit^® is a physical activity program and sport which is based on functional movements performed at high intensity and with high variability of exercises. It develops all motor skills. The study included 424 athletes (266 men and 158 women) from twelve centers in Poland, actively practicing CrossFit^® between 18 and 60 years of age. A questionnaire consisting of 25 questions was used, which was divided into four subsections concerning the characteristics of the sample, training routine, injuries, and information about environment. In total, 48% of respondents participating in the study suffered at least one injury during their entire training history. The injuries suffered most often involved shoulder joint and lumbar spine. Men were found to face a higher risk of injury than women, at 32.78% vs. 15.33% (p = 0.027). The shorter the training period, the smaller the number of injuries observed among the trainees. It was also noted that the shorter the training period, the lower the number of injuries that occurred (p = 0.041). An increase in the number of training sessions per week did not increase the incidence of injuries (p > 0.05). Performing isometric exercises during warm-up reduced the likelihood of injury during CrossFit^® training itself (p = 0.012). Training despite of concomitant acute pain had a significant adverse effect on the incidence of injuries (p = 0.002). The most common risk factors for injury in the CrossFit^® training process include, in particular: gender, training experience, and length of training sessions. Proper warm-up including isometric exercises and training conducted without accompanying pain symptoms reduces the risk of injury.

Acute physiological outcomes of high-intensity functional training: a scoping review

Background

Systematic reviews and meta-analyses related to high-intensity functional training (HIFT) have been conducted. However, due to a restricted pool of available research, these investigations are often limited in scope. As such, a scoping review investigating the present literature surrounding the acute physiological response to HIFT-based exercise was chosen as a more appropriate structured review.

Methodology

A scoping review was conducted following Arksey and O'Malley's framework. Three large scale databases were searched to reveal any article pertaining to HIFT and related exercise terminology.

Results

A total of 2,241 articles were found during the initial search. Following this, titles, then abstracts, and full-texts were reviewed to determine inclusion eligibility. A total of 60 articles which investigated a combined total of 35 unique HIFT workouts were included within this review.

Conclusions

A variety of physiological parameters and HIFT workouts have been examined. Markers of intensity (e.g., blood lactate concentrations, heart rate) have been most consistently assessed across all studies, and these support the idea that HIFT workouts are typically performed at high-intensity. In contrast, the inclusion of most other measures (e.g., hormonal, markers of inflammation and damage, energy expenditure, performance) has been inconsistent and has thus, limited the possibility for making generalized conclusions. Differences in study methodologies have further impacted conclusions, as different studies have varied in sample population characteristics, workouts assessed, and time points. Though it may be impossible to comprehensively research all possible HIFT workouts, consistent adoption of population definitions and workload quantification may overcome this challenge and assist with future comparisons.

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.

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.

Upper Extremity Injuries in CrossFit Athletes-a Review of the Current Literature

PURPOSE OF REVIEW

Cross-discipline fitness, or CrossFit, has exploded in popularity during the last two decades. During this time, there have been a high volume of patients presenting to clinicians with a wide range of associated injuries. Given the high intensity, high repetition, and competitive nature of CrossFit training and competition, athletes are vulnerable to injury, particularly upper extremity injury. The rate of injury to the shoulder, elbow, and wrist in CrossFit is higher when compared to traditional weight-training and more comparable to elite-level gymnastics and Olympic-style lifting. Due to the growing popularity of CrossFit-style exercise and the relatively high rate of injury among its participants, clinicians are likely to encounter these athletes. The purpose of this review is to familiarize clinicians with CrossFit and the associated injuries they will likely encounter.

RECENT FINDINGS

The medical literature focusing on CrossFit has demonstrated exponential growth, with the first article published in 2012 and 59 articles published in 2020. Although the body of literature is growing, there are no high-level studies focusing on CrossFit. The literature mainly consists of level IV and V studies, primarily consisting of case reports and case series. Recent studies have proven that CrossFit athletes are vulnerable to high rates of upper extremity injury and a few studies have identified risk factors for injury. Future high-level research is required to study modifiable risk factors, diagnostic criteria, and treatment options for these high-risk athletes in order to improve the safety of their sport. The CrossFit body of research is limited to level IV and V studies; however, the literature is clear, CrossFit athletes face a high rate of upper extremity injury. For this reason, clinicians must be familiar with CrossFit and its associated pathology. The goal of this review is to familiarize clinicians with CrossFit and the associated pathologies they will likely encounter.

The aging athlete

Aging athletes, those 60 years and older, are a growing population of mature, active individuals who value sports and exercise participation throughout their lifespan. Although recommendations for younger and masters athletes have been extrapolated to this population, there remains a paucity of specific guidelines, treatment algorithms, and considerations for aging athletes. The benefits of living an active lifestyle must be weighed against the risks for unique cardiovascular, metabolic, and musculoskeletal injuries requiring diagnostic and therapeutic interventions. In this article, we review the unique cardiovascular and muscular physiology of aging athletes and how it influences the risk of specific medical conditions. We also discuss general prevention and treatment strategies. Finally, we identify areas of future research priorities and emerging treatments.

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.

Disease burden of osteoarthritis of the knee and hip due to a high body mass index in China and the USA: 1990-2019 findings from the global burden of disease study 2019

Background

Osteoarthritis (OA) is a leading cause of disability and a source of societal costs among older adults, especially with an increasingly obese population. However, very few published studies have investigated the burden of knee and hip OA due to a high body mass index (BMI). Therefore, this study aimed to systematically summarize the trends of knee and hip OA due to a high BMI in China and the USA between 1990 and 2019.

Methods

Data from the Global Burden of Disease Study 2019 were used to estimate the age-standardized prevalence, disability-adjusted life years (DALYs) rates of knee and hip OA, and the burden of knee and hip OA due to a high BMI by sex. Joinpoint regression analysis was used to determine the temporal trend changes in the related DALYs rates of knee and hip OA.

Results

The trends in the DALYs rates of knee OA due to a high BMI have shown a steady and large increase in China, while the trends first showed an increase followed by a large decrease near 2001-2005 and finally a steady increase in the USA. The trends in the DALYs rates of hip OA due to a high BMI have shown a steady and large increase in both men and women in China and the USA from 1990 to 2019. For the comparison by age categories from 30 to 34 years to 90–94 years in 2019, the age-standardized DALYs rates due to a high BMI first increased and then decreased after 60–64 years and 70-74 years in both men and women from China and the USA for knee OA, respectively. For hip OA, the age-standardized DALYs rates first increased and then decreased after 70–74 years in both men and women from China and the USA.

Conclusions

The burden of knee and hip OA due to a high BMI is substantially increasing in China and the USA in recent years. Researchers and health policy makers should assess the changing patterns of high BMI on the burden of OA and devise corresponding weight-control strategies.

Injury profile in CrossFit® practitioners: Prevalence and associated factors during a year of sports practice

ABSTRACT This study aimed to investigate the prevalence of injuries in CrossFit® practitioners and the influence of sports practice and demographic characteristics on these injuries. A retrospective cohort study was carried out with 180 CrossFit® practitioners who answered a questionnaire with demographic characteristics (age, body mass, height, and sex), sports characteristics (number of years practicing CrossFit®; training frequency, duration, and training program; and practice of other sports), and presence of any injury suffered and its characteristics (number of injuries, region, and type of injury). The Mann-Whitney U test investigated the difference in continuous variables between those with and without injury history. The chi-square test and Fisher’s exact test investigated the association between categorical variables and the presence or not of injury over the last year. The chi-square goodness-of-fit test investigated if the frequency of injuries per body location and type differed from the expected one. Injury prevalence was 63%. Participants with a history of injury showed a shorter time of CrossFit® practice. The presence of injury history was associated with lesser weekly and daily training frequency, shorter training duration, and Scale training program. The frequency of injuries on leg, knee, lumbar spine, shoulder, and wrist, and the muscle and tendon was greater than expected. The other variables were neither different between groups nor associated with injury presence. Thus, most participants presented injury over the last year, influenced by the sports characteristics but not by demographic characteristics.

Perfil de lesões em praticantes de CrossFit®: prevalência e fatores associados durante um ano de prática esportiva

RESUMO Este estudo teve como objetivo investigar a prevalência de lesões durante um ano em praticantes de CrossFit® e a influência das características da prática esportiva e demográficas nessas lesões. Foi realizado estudo de coorte retrospectivo com 180 praticantes de CrossFit®, que responderam a um questionário sobre: características demográficas (idade, massa corporal, altura e sexo), características da prática esportiva (tempo de prática esportiva, frequência e duração de treino, formação de carga e prática de outro esporte) e ocorrência e características da lesão (quantidade, região lesionada e estrutura acometida). Por meio do teste de Mann-Whitney U, investigou-se a diferença nas variáveis contínuas entre aqueles com e sem histórico de lesão. Utilizando o teste de qui-quadrado e o teste exato de Fisher, avaliou-se a associação entre variáveis categóricas e a presença ou não de lesão. O teste de qui-quadrado goodness-of-fit foi aplicado para investigar se a frequência observada de lesões por região do corpo e por tipo era diferente da esperada. A prevalência de lesão foi de 63%, e aqueles com histórico de lesão tinham menor tempo de prática esportiva. A presença de histórico de lesão foi associada a menor frequência semanal e diária e menor duração de treinos, assim como à formação de carga Scale. A frequência de lesão em perna, joelho, coluna lombar, ombro e punho, assim como do tipo músculo e tendão foi acima da esperada. As demais variáveis não apresentaram diferença entre grupos ou não foram associadas à presença de lesão. Logo, a maioria dos investigados relatou lesão que foi influenciada pelas características da prática esportiva, e não pelas demográficas.

Isokinetic force-power profile of the shoulder joint in males participating in CrossFit training and competing at different levels

Background

As participants who engage in CrossFit training and competition perform a large volume of high intensity overhead activities, injuries to the shoulder are one of the most common in this sport. Previous research in other sports has indicated that the isokinetic force power profile of the shoulder joint (IPSJ) rotator muscles may assist in the prediction of shoulder injury.

Aim

Therefore, the objective of this study was to determine the IPSJ in males engaged in CrossFit training at different competitive levels.

Methods

In a cross-sectional study design, participants (age, 24.1 ± 2.7 years) classified as ‘beginner’ (n = 6), ‘intermediate’ (n = 7) or ‘advanced’ (n = 9) provided informed consent to participate in this study. The IPSJ assessment involved rotational and diagonal movements, including internal and external shoulder rotator muscles, at both 180°.s⁻¹ and 300°.s⁻¹. The variables analysed were peak torque/body mass (%), mean power (W) and the external/internal peak torque/body mass ratio (%). A Kruskal–Wallis test was used to compare the IPSJ of the three groups, with Dunn’s test used for post-hoc analysis. The alpha level was set at p < 0.05.

Results

The IPSJ showed greater torque and power values in those who competed at the advanced level as compared to those at a lower competitive level (i.e. intermediate, beginner). This was observed mainly for the internal rotation and internal diagonal movements at both 180°.s⁻¹ and 300°.s⁻¹. However, such differences between competitive levels were, in general, absent for the external rotation and external diagonal movements. Moreover, the participants from the advanced competitive level exhibited an imbalance of peak torque between the muscles responsible for the external–internal rotational and external-internal diagonal movements of the shoulder (i.e. peak torque external/internal ratio <66%), particularly in the dominant shoulder.

Conclusion

These findings suggest greater development of the shoulder internal rotators and a higher probability of shoulder injury in CrossFit athletes at the advanced competitive level. Based on these results, participants engaged in CrossFit training and competition may wish to increase the volume of training for the shoulder external rotator muscles to complement the large increases in shoulder internal rotator strength that occur as a part of their regular training regimes.

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.