Impact-Induced Muscle Damage and Contact Sports: Etiology, Effects on Neuromuscular Function and Recovery, and the Modulating Effects of Adaptation and Recovery Strategies

Abstract

Athletes involved in contact sports are habitually exposed to skeletal-muscle damage in their training and performance environments. This often leads to exercise-induced muscle damage (EIMD) resulting from repeated eccentric and/or high-intensity exercise and to impact-induced muscle damage (IIMD) resulting from collisions with opponents and the playing surface. While EIMD has been an area of extensive investigation, IIMD has received comparatively little research, with the magnitude and time frame of alterations following IIMD not presently well understood. It is currently thought that EIMD results from an overload of mechanical stress that causes ultrastructural damage to the cellular membrane constituents. Damage leads to compromised ability to produce force, which manifests immediately and persists for up to 14 d following exercise exposure. IIMD has been implicated in attenuated neuromuscular performance and recovery and in inflammatory processes, although the underlying course over time remains unclear. Exposure to EIMD leads to an adaptation to subsequent exposures, a phenomenon known as the repeated-bout effect. An analogous adaptation has been suggested to occur following IIMD; however, to date, this contention remains equivocal. While a considerable body of research has explored the efficacy of recovery strategies following EIMD, strategies promoting recovery from IIMD are limited to investigations using animal contusion models. Strategies such as cryotherapy and antioxidant supplementation that focus on attenuating the secondary inflammatory response may provide additional benefit in IIMD and are explored herein. Further research is required to first establish a model of generating IIMD and then explore broader areas around IIMD in athletic populations.

Quantifying the Collision Dose in Rugby League: A Systematic Review, Meta-analysis, and Critical Analysis

“…During this phase, the athletes involved wrestle or grapple to achieve dominance in the tackle and this necessitates large muscular force generation whilst in a near stationary position [75]. These static exertions involve isometric and eccentric muscle actions that are likely to produce extensive muscle damage [27] and incur substantial energetic costs [75]. Despite the apparent high energetic demand of such events, microtechnology is incapable of quantifying the work completed in a stationary position due to minimal displacement of the device [75,76].…”

“…Whilst postcollection processing of the data to remove errors may be considered a limitation, this information enables applied practitioners to attain a similar level of accuracy when monitoring collisions via microtechnology. Indeed collisions of low duration and intensity may not be as physically or perceptually fatiguing as those of higher durations and intensities [27]. As such, it may be less pertinent to consider these collisions in the context of contact load monitoring.…”

“…Indeed, various methods to quantify physical or collision workload intensity have been suggested in the research including subjective measures such as rating of perceived challenge [78], rating of perceived exertion (RPE) [79], and rating of mental effort [79]. Others have investigated intensity based on objective markers including muscle damage biomarkers (such as creatine kinase) [27] and shoulder impact forces [80]. As there is currently no gold standard and a lack of consensus in regard to the measure(s) that appropriately capture collision intensity, future research into the validation of collision intensity and load metrics as reported via microtechnology is warranted.…”

“…Automating this process would streamline analysis and provide practitioners with further detailed information on contact loads. This would inform short-and longterm collision load monitoring and allow for the exploration of interactions with contact-related injuries [31], contact adaptation [27], and the effects of contact skill and conditioning programmes [4,85].…”

“…Additionally, the rugby league is characterised by collisions between teammates, opponents, and the playing surface [26]. These collisions typically occur between the tackler(s) and the ball carrier during the tackle event and have been reported to lead to soreness and muscle damage which compromises muscle integrity, attenuates force generation capacity, and has the potential to delay athletic recovery [27]. Additionally, the vast majority (9 4%) of match-related injuries in the professional rugby league are tackle related [28].…”