Effects of injury proneness and task difficulty on joint kinetic variability

ArticleinMedicine & Science in Sports & Exercise 32(11):1833-44 · November 2000with15 Reads
DOI: 10.1097/00005768-200011000-00004 · Source: PubMed
Abstract
The purpose was to investigate the effects of lower extremity overuse injury proneness and landing height on the variability of selected joint moment characteristics. Ten subjects from each of two groups (healthy and injury prone) performed 10 landings from a platform (heights: 50, 100, and 200% of maximum vertical jump). Force platform (1000 Hz) and video (200 Hz) information were collected and used to compute ankle, knee, and hip joint moment values during impact (0-100 ms post contact). Moment peak, time to peak, and impulse values were used to determine variability across 10 trials for each subject and height. MANOVAs and univariate follow-up tests were used to assess variability differences between groups and among heights. Results revealed ankle moment variability differences (P < or = 0.05; Tukey) between groups for peak and time to peak variables at the 100% and 50% heights, respectively. The injury-prone group exhibited greater variability for the peak variable, whereas the healthy group showed greater variability for the temporal variable. Groups also differed on the impulse variables (P < or = 0.02; MANOVA), but follow-up tests failed to determine specific joints or directions of differences. Both groups exhibited tendencies for greater variability (P < or = 0.05; Tukey) with increases in height up to 100% MVJ and decreases in variability with further height increases. Results suggest that groups differed in joint moment variability, possibly indicating a relationship between variability and overuse injuries, although the variables and directions of differences were inconsistent. For some variables, variability increased and then decreased with height increases for both groups, suggesting a range of heights within which the neuromuscular system adapted.
    • "Limited movement variability reduces task complexity via decreasing the degrees of freedom used in the task, this in turn may reach a critical tissue threshold whereby injury occurs (Hamill et al., 2012 ). An injury may occur via the load being unable to distributed across many structures or a shorter duration between loading events, increasing the likelihood of tissue maladaptation (James et al., 2000). Movement variability has been shown to discriminate runners with a history of low back pain from those without a history and current low back pain (Seay et al., 2011). "
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    Article · Jul 2016
    • "Consequently, this allows better load distribution among different tissues (Bartlett et al., 2007; James et al., 2000), different areas within the same tissue, or within the same tissue or location but at different times (James et al., 2000). This has the potential to allow the detrimental effects of repetitive loading to be reduced by enabling a longer adaptation time for tissues between loading events (James et al., 2000). Decreasing the likelihood of tissue maladaptation can be achieved by increasing the number of available movement pattern options between segments or coupled joints via increasing the degrees of freedom utilised to perform a task (Hamill et al., 2012), which in turn, increases movement variability. "
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    • "Movement variability may be considered a protective mechanism against overuse injuries by altering the characteristics of loading application to minimise accumulation of load in a central region (James, et al., 2000), and the detrimental effects of repetitive loading may be reduced by enabling longer adaptation time for tissues between loading events (James, et al., 2000). This suggests that if an individual displays a lack of movement variability in response to ever changing task demands and environmental conditions, they may utilise rigid, inflexible motor behaviours with limited adaptability (Stergiou, Harbourne, & Cavanaugh, 2006), and increase the risk of developing an overuse injury (James, et al., 2000; Bartlett, et al., 2007). The effect of fatigue during the SSC lead to high response variability and large interindividual variations (Regueme, Nicol, Barthelemy, & Grelot, 2005), which may explain why the only moderate difference between fatigue conditions was decreased knee flexion at the time of the peak F VL . "
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