Abstract
BackgroundAs 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.AimTherefore, the objective of this study was to determine the IPSJ in males engaged in CrossFit training at different competitive levels.MethodsIn 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.ResultsThe 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.ConclusionThese 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.
Highlights
CrossFit is practiced in 142 countries worldwide (Claudino et al, 2018) and involves participants competing in a range of diverse athletic events ranging from those requiring short-duration maximal efforts to longerduration, lower-intensity efforts, with some events offering information on the nature of competition only a few moments prior to participation (Pritchard, Keogh & Winwood, 2020)
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
The greater mean power values in the advanced level group might be associated with the higher training loads undertaken by that cohort compared to the intermediate and beginner participants, this needs further confirmation our findings suggest that isokinetic muscle power could help to characterise differences between competitive levels among male CrossFit training participants
Summary
CrossFit is practiced in 142 countries worldwide (Claudino et al, 2018) and involves participants competing in a range of diverse athletic events ranging from those requiring short-duration maximal efforts (e.g. one repetition maximal barbell lifting) to longerduration, lower-intensity efforts (e.g. endurance-dominant events), with some events offering information on the nature of competition only a few moments prior to participation (Pritchard, Keogh & Winwood, 2020). Several studies report that the shoulder joint is the most affected by overuse injuries in Crossfit practitioners (Klimek et al, 2018), in males (Dominski et al, 2018; Weisenthal et al, 2014) This finding is supported by the results of a systematic review of weight training sports, such as weightlifting, strongman and powerlifting, in which the shoulder is typically the most frequently injured body part due to the execution of heavily loaded overhead exercises (Keogh & Winwood, 2017). 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. The participants from the advanced competitive level exhibited an imbalance of peak torque between the
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