The Influence of Exercise-Induced Fatigue on Inter-Limb Asymmetries: a Systematic Review

Abstract

Background Non-contact injuries such as anterior cruciate ligament ruptures often occur during physical load toward the end of a match. This is ascribed to emerging processes due to exercise-induced fatigue. Moreover, non-contact injuries often occur during dynamic actions such as landing or cutting movements. Inter-limb asymmetries are suggested as one possible cause for those injuries based on findings indicating that asymmetries between limbs are associated with a higher injury risk. Hence, assessing inter-limb asymmetry during physical load in the condition of exercise-induced fatigue is warranted to identify potentially relevant precursors for non-contact injuries. Objective The objective of this study was to overview the current state of evidence concerning the influence of exercise-induced fatigue on inter-limb asymmetries through a systematic review. Methods A systematic literature search was conducted using the databases Web of Science, Scopus, PubMed, SURF, and SPONET to identify studies that assessed inter-limb asymmetries of healthy people, calculated with an asymmetry equation, before and after, or during a loading protocol. Results Thirteen studies were included in the systematic review. The loading protocols involved running, race walking, jumping, squatting, soccer, rowing, and combinations of different exercises. Moreover, different tasks/procedures were used to assess inter-limb asymmetries, e.g., squats, single-leg countermovement jumps, gait analysis, or isokinetic strength testing. The results seem to depend on the implemented loading protocol, the tasks/procedures, and the measured parameters. Conclusions Future research needs more systematization and consistency, assessing the effect of exercise-induced fatigue on inter-limb asymmetries. Moreover, the emergence of inter-limb asymmetries should be regarded in the context of sport-specific movements/tasks. Testing before, after, and during a physical loading protocol is advisable to consider the influence of exercise-induced fatigue on sport-specific tasks and to identify the possible mechanisms underlying load-dependent inter-limb asymmetries with regard to risk of non-contact injury.

Spatio-temporal gait parameters obtained from foot-worn inertial sensors are reliable in healthy adults in single- and dual-task conditions

“…Recent results of Wei et al (2017) further revealed that gait asymmetry is an important factor for the prediction of falls in stroke patients 68 . Also of note is that chronic gait asymmetry could also lead to increased risk of lower-limb overuse injuries and articular joint degeneration due to the increased weight bearing and propulsion demands placed on one lower limb during walking, in both pathological 69 – 72 and healthy populations 73 . Along these lines, gait asymmetry can be used as (i) a metric to assess pathology status, patients’ functional recovery or disease progression, (ii) a target for interventions aiming to improve gait performance, and (iii) outcome to evaluate and compare different gait rehabilitation programs interventions 43 , 55 , 74 – 77 .…”

The Influence of Physical Load on Dynamic Postural Control—A Systematic Replication Study

“…However, all the subjects with a side-difference greater than 4 cm had composite scores under 94% post-load, indicating an especially high potential injury risk for these subjects. In future work, given inter-individual variation and task-specificity of side-differences, a more individual approach seems advisable [33,49]. Nevertheless, the prediction of the likelihood of injuries using the YBT has recently been doubted [50], and the particular YBT is not able to give an overall impression of all types of dynamic postural control.…”

“…For example, Wright et al [20] found a negative effect after running but not after cycling, suggesting that the results may additionally depend on the type of load and the induced type of fatigue (whole body vs. local) [20]. This loading protocol specificity should also be considered during future studies [29] and the used tasks and protocols should try to mimic the sport-specific demands [33].…”

“…might not be stressed equally by the loading protocols [20,29], and the protocols might induce different types of fatigue (whole body vs. local) [20]. Nevertheless, loading protocols should reflect sport-specific demands and situations in order to be able to make reliable and consistent statements [32,33].…”

“…Furthermore, both legs are involved in sporting movements, injuries can occur in both legs [34] and corresponding side-differences are an additional factor enhancing the likelihood for non-contact injuries [8,33]. However, most of the studies assessed dynamic postural control of only one leg [3][4][5]16,20,22], usually of the 'dominant leg', mostly defined as the athlete's kicking leg [3,5] or the 'take-off leg' [4].…”