A comparison of methods to determine bilateral asymmetries in vertical leg stiffness

Abstract

Whilst the measurement and quantification of vertical leg stiffness (K vert ) asymmetry is of important practical relevance to athletic performance, literature investigating bilateral asymmetry in K vert is limited. Moreover, how the type of task used to assess K vert may affect the expression of asymmetry has not been properly determined. Twelve healthy males performed three types of performance tasks on a dual force plate system to determine K vert asymmetries; the tasks were (a) bilateral hopping, (b) bilateral drop jumping and (c) unilateral drop jumping. Across all the three methods, K vert was significantly different between compliant and stiff limbs (P < 0.001) with a significant interaction effect between limb and method (P = 0.005). Differences in K vert between compliant and stiff limbs were −5.3% (P < 0.001), −21.8% (P = 0.007) and −15.1% (P < 0.001) for the bilateral hopping, bilateral drop jumping and unilateral drop jumping methods, respectively. All the three methods were able to detect significant differences between compliant and stiff limbs, and could be used as a diagnostic tool to assess K vert asymmetry. Drop jumping tasks detected larger K vert asymmetries than hopping, suggesting that asymmetries may be expressed to a greater extent in acyclic, maximal performance tasks.

Do stiffness and asymmetries predict change of direction performance?

“…Despite the magnitude of the difference in vertical stiffness between the fast and slow groups, differences in vertical ground reaction force and centre of mass displacement were not significant and only the former was associated with a 'moderate' effect size. This is not in agreement with a previous findings which identify centre of mass displacement as a strong factor in determining vertical stiffness asymmetry (Maloney et al, 2015), although it should be noted that the current study expressed vertical ground reaction force relative to body mass whereas the previous investigation analysed raw values.…”

“…Nonetheless, it is likely that asymmetries in both factors have an additive effect that is exhibited in vertical stiffness asymmetry (Maloney et al, 2015).…”

“…In addition, Pruyn et al (2014) determined vertical stiffness during a cyclic, unilateral hopping task. It has since been observed that the expression of vertical stiffness and associated asymmetries is highly task dependant (Maloney, Fletcher, & Richards, 2015). As a change of direction may be characterised as acyclic, ballistic and unilateral in nature, the unilateral drop jump is likely to demonstrate the greatest correspondence to CODS and may therefore carry greater validity as an assessment for vertical stiffness Several investigations have reported that asymmetries in force/power qualities may be detrimental to athletic performance (Bailey, Sato, Alexander, Chiang, & Stone, 2013;Bailey, Sato, Burnett, & Stone, 2015;Bazyler, Bailey, Chiang, Sato, & Stone, 2014;Bell, Sanfilippo, Binkley, & Heiderscheit, 2014;Hart, Nimphius, Spiteri, & Newton, 2014), however, this relationship is not clear in regards to CODS.…”

Is stiffness related to athletic groin pain?

“…Negative whole‐body power was calculated as the external work done per unit time in an attempt to bring the body to a resting state. While many studies have calculated stiffness from initial contact to peak vertical ground reaction force, the authors felt the eccentric phase more useful given that the timing of peak vertical ground reaction force varied considerably (mean ± SD: 41.3 ± 12.0% of total ground contact), with 33% of all participants producing their peak force during the whole‐body concentric phase. When examining the moment‐angle waveforms of the hurdle hop task in this present study, not all joints demonstrated a clear biphasic pattern as presented in previous research .…”

Vertical and Horizontal Asymmetries Are Related to Slower Sprinting and Jump Performance in Elite Youth Female Soccer Players

“…The notion of inter-limb asymmetries refers to the function of one limb in respect to the other and has been a popular source of investigation in recent years. The majority of literature has focused on the prevalence of between-limb differences in multiple testing modalities such as isokinetic dynamometry (14,37), isometric squat or mid-thigh pulls (16,19), back squatting (30,38), and a variety of jumping-based tasks (3,12,27,28). All of the aforementioned methods have been shown to be sensitive when identifying differences between limbs in both athlete and non-athlete populations.…”