Leg power and hopping stiffness: relationship with sprint running performance (original) (raw)
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Application of Leg, Vertical, and Joint Stiffness in Running Performance: A Literature Overview
Applied Bionics and Biomechanics
Stiffness, the resistance to deformation due to force, has been used to model the way in which the lower body responds to landing during cyclic motions such as running and jumping. Vertical, leg, and joint stiffness provide a useful model for investigating the store and release of potential elastic energy via the musculotendinous unit in the stretch-shortening cycle and may provide insight into sport performance. This review is aimed at assessing the effect of vertical, leg, and joint stiffness on running performance as such an investigation may provide greater insight into performance during this common form of locomotion. PubMed and SPORTDiscus databases were searched resulting in 92 publications on vertical, leg, and joint stiffness and running performance. Vertical stiffness increases with running velocity and stride frequency. Higher vertical stiffness differentiated elite runners from lower-performing athletes and was also associated with a lower oxygen cost. In contrast, leg ...
Interaction Between Leg Muscle Performance and Sprint Acceleration Kinematics
This study investigated relationships between 10 m sprint acceleration, step kinematics (step length and frequency, contact and flight time), and leg muscle performance (power, stiffness, strength). Twenty-eight field sport athletes completed 10 m sprints that were timed and filmed. Velocity and step kinematics were measured for the 0-5, 5- 10, and 0-10 m intervals to assess acceleration. Leg power was measured via countermovement jumps (CMJ), a fivebound test (5BT), and the reactive strength index (RSI) defined by 40 cm drop jumps. Leg stiffness was measured by bilateral and unilateral hopping. A three-repetition maximum squat determined strength. Pearson’s correlations and stepwise regression (p ≤ 0.05) determined velocity, step kinematics, and leg muscle performance relationships. CMJ height correlated with and predicted velocity in all intervals (r = 0.40-0.54). The 5BT (5-10 and 0-10 m intervals) and RSI (5-10 m interval) also related to velocity (r = 0.37-0.47). Leg stiffness did not correlate with acceleration kinematics. Greater leg strength related to and predicted lower 0-5 m flight times (r = -0.46 to -0.51), and a longer 0-10 m step length (r = 0.38). Although results supported research emphasizing the value of leg power and strength for acceleration, the correlations and predictive relationships (r2 = 0.14-0.29) tended to be low, which highlights the complex interaction between sprint technique and leg muscle performance. Nonetheless, given the established relationships between speed, leg power and strength, strength and conditioning coaches should ensure these qualities are expressed during acceleration in field sport athletes.
The effect of speed on leg stiffness and joint kinetics in human running
Journal of Biomechanics, 1999
The goals of this study were to examine the following hypotheses: (a) there is a difference between the theoretically calculated (McMahon and Cheng, 1990. Journal of Biomechanics 23, 65–78) and the kinematically measured length changes of the spring–mass model and (b) the leg spring stiffness, the ankle spring stiffness and the knee spring stiffness are influenced by running speed. Thirteen
Journal of Biomechanics, 2012
It is not presently clear whether mathematical models used to estimate leg stiffness during human running are valid. Therefore, leg stiffness during the braking phase of ground contact of running was calculated directly using synchronous kinematic (high-speed motion analysis) and kinetic (force platform) analysis, and compared to stiffness calculated using four previously published kinetic models. Nineteen well-trained male middle distance runners (age¼21.174.1 yr; VO 2max ¼ 69.577.5 mlO 2 kg À 1 min À 1) completed a series of runs of increasing speed from 2.5 to 6.5 m s À 1. Leg stiffness was calculated directly from kinetic-kinematic analysis using both vertical and horizontal forces to obtain the resultant force in the line of leg compression (Model 1). Values were also estimated using four previously published mathematical models where only force platform derived and anthropometric measures were required (Models 2-5; Morin et al., 2005, Morin et al., 2011, Blum et al., 2009, Farley et al., 1993, respectively). The greatest statistical similarity between leg stiffness values occurred with Models 1 and 2. The poorest similarity occurred when values from Model 4 were compared with Model 1. Analyses suggest that the poor correlation between Model 1 other models may have resulted from errors in the estimation in change in leg length during the braking phase. Previously published mathematical models did not provide accurate leg stiffness estimates, although Model 2, used by Morin et al. (2005), provided reasonable estimates that could be further improved by the removal of systematic error using a correction factor (K¼ 1.0496 K Model2). & 2012 Elsevier Ltd. All rights reserved. stiffness increased with running velocity whilst McMahon and Cheng (1990) did not. Meanwhile Blum et al. (2009) reported that a model utilising kinetic parameters, body mass, leg length and touchdown angle predicted similar leg stiffness values to the method proposed by McMahon and Cheng (1990). Other studies Contents lists available at SciVerse ScienceDirect
Sprint mechanical differences at maximal running speed: Effects of performance level
As the effect of performance level on sprinting mechanics has not been fully studied, we examined mechanical differences at maximal running speed (MRS) over a straight-line 35 m sprint amongst sprinters of different performance levels. Fifty male track and field sprinters, divided in Slow, Medium and Fast groups (MRS: 7.67 ± 0.27 m•s −1 , 8.44 ± 0.22 m•s −1 , and 9.37 ± 0.41 m•s −1 , respectively) were tested. A high-speed camera (250 Hz) recorded a full stride in the sagittal plane at 30-35 m. MRS was higher (p < 0.05) in Fast vs. Medium (+11.0%) and Slow (+22.1%) as well as in Medium vs. Slow (+10.0%). Twelve, eight and seven out of 21 variables significantly distinguished Fast from Slow, Fast from Medium and Medium from Slow sprinters, respectively. Propulsive phase was significantly shorter in Fast vs. Medium (−17.5%) and Slow (−29.4%) as well as in Medium vs. Slow (−14.4%). Fast sprinters had significantly higher vertical and leg stiffness values than Medium (+44.1% and +18.1%, respectively) and Slow (+25.4% and +22.0%, respectively). MRS at 30-35 m increased with performance level during a 35-m sprint and was achieved through shorter contact time, longer step length, faster step rate, and higher vertical and leg stiffness.
Changes in spring-mass model characteristics during repeated running sprints
European Journal of Applied Physiology, 2011
This study investigated fatigue-induced changes in spring-mass model characteristics during repeated running sprints. Sixteen active subjects performed 12 × 40 m sprints interspersed with 30 s of passive recovery. Vertical and anterior–posterior ground reaction forces were measured at 5–10 m and 30–35 m and used to determine spring-mass model characteristics. Contact (P < 0.001), flight (P < 0.05) and swing times (P < 0.001) together with braking, push-off and total stride durations (P < 0.001) lengthened across repetitions. Stride frequency (P < 0.001) and push-off forces (P < 0.05) decreased with fatigue, whereas stride length (P = 0.06), braking (P = 0.08) and peak vertical forces (P = 0.17) changes approached significance. Center of mass vertical displacement (P < 0.001) but not leg compression (P > 0.05) increased with time. As a result, vertical stiffness decreased (P < 0.001) from the first to the last repetition, whereas leg stiffness changes across sprint trials were not significant (P > 0.05). Changes in vertical stiffness were correlated (r > 0.7; P < 0.001) with changes in stride frequency. When compared to 5–10 m, most of ground reaction force-related parameters were higher (P < 0.05) at 30–35 m, whereas contact time, stride frequency, vertical and leg stiffness were lower (P < 0.05). Vertical stiffness deteriorates when 40 m run-based sprints are repeated, which alters impact parameters. Maintaining faster stride frequencies through retaining higher vertical stiffness is a prerequisite to improve performance during repeated sprinting.
Determinants of difference in leg stiffness between endurance- and power-trained athletes
Journal of Biomechanics, 2008
Understanding the leg and joint stiffness during human movement would provide important information that could be utilized for evaluating sports performance and for injury prevention. In the present study, we examined the determinants of the difference in the leg stiffness between the endurance-trained and power-trained athletes. Seven distance runners and seven power-trained athletes performed in-place hopping, matching metronome beats at 3.0 and 1.5 Hz. Leg and joint stiffness were calculated from kinetic and kinematics data. Electromyographic activity (EMG) was recorded from six leg muscles. At both hopping frequencies, the power-trained athletes demonstrated significantly higher leg stiffness than the distance runners. Hip, knee, and ankle joints were analyzed for stiffness and touchdown angles. Ankle stiffness was significantly greater in the power-trained athletes than the distance runners at 3.0 Hz as was knee stiffness at 1.5 Hz. There was no significant difference in touchdown angle between the DR and PT groups at either hopping frequencies. When significant difference in EMG activity existed between two groups, it was always greater in the distance runners than the powertrained athletes. These results suggest that (1) the difference in leg stiffness between endurance-trained and power-trained athletes is best attributed to increased joint stiffness, and (2) the difference in joint stiffness between the two groups may be attributed to a lack of similarity in the intrinsic stiffness of the muscle-tendon complex rather than in altered neural activity.
The use of various strength-power tests as predictors of sprint running performance
Backround. The present study assessed the relationship between various strength-power tests and maximal running velocity parameters. Methods. Nine trained males were tested on four separate occasions. On the first occasion the maximum running velocity (MRV), stride rate (SR) and stride length (SL) were measured over 35 m. On the second occasion maximal vertical jumps [squat jump (SJ), standing broad jump (SJ), counter movement jump (CMJ) and drop jumps (DJ) from heights of 30, 50 and 80 cm] were performed on a force platform: On the third occasion the maximal bilateral isometric force (MBIF) of leg extensors and the force time characteristics (f-t 10-30%, f-t 10-60% and f-t 10-90%) were determined using a leg extension machine connected to a force plate. On the final fouth occasion peak anaerobic power was measured via repeated 6 s maximum cycle sprints. Pearson product-moment correlation coefficients were calculated for all the aformentioned parameters. Results. The correlation coefficients showed that MRV correlated significantly with f-t 10-60% and DJ30 (r = -0.73 and r =0.73, p<0.05 respectively). In addition, SR and SL showed significant, and critical for SR, relationship with f-t 10-60% (r = -0.82, p<0.01 and r = 0.75, p<0.05 respectively). Conclusions. The present findings suggest that the ability to produce force quickly, as measured by the time to achieve 60% of maximum voluntary contraction is related to sprinting performance, with the coefficient of determination accounting for 53% of the variance in the data. These data also showed that sprinting ability is linked with drop jumping performance, especially the drop jump from a height of 30 cm. It is suggested that the above tests may prove useful in preparing and testing the sprinting ability and sprint specific strength levels.
International Journal of Environmental Research and Public Health
Background: Musculotendinous reactive strength is a key factor for the utilization of elastic energy in sporting activities such as running. AIM: To evaluate the relationship between musculotendinous reactive strength and lower-limb stiffness during running as well as to identify age-related differences in both variables. Methods: Fifty-nine amateur endurance runners performed three 20-cm drop jumps and a constant 3-min easy run on a motorized treadmill. Reactive strength index and dynamic lower-limb stiffness were calculated with a photoelectric cell system by jumping and running, respectively. Additionally, sit to stand difference in plantar arch height was assessed as a static lower-limb stiffness measure. The cluster analysis allows the comparison between younger and older runners. Results: No significant correlations were found between jumping reactive strength and running lower-limb stiffness. The younger group performed better at drop jumps (p = 0.023, ES = 0.82), whereas hig...
Vertical Stiffness, Jumps and Sprint Kinematics of Well-Trained Youth Female and Male Sprinters
journal biology of exercise
Maximal sprint speed and kinematic step characteristics depend on the vertical stiffness (K vert) and jump strength, which are tested by vertical jumps with short (hopping jump (HT), drop jump (DJ)) and long (counter movement jump (CMJ)) stretch shortening cycle. The purpose was to determine the reproducibility of a HT, and the differences of sprint speed, K vert as well as DJ and CMJ height between groups. Male junior national squad, male and female Hamburger regional squad athletes were measured in flying 30 m sprint and vertical jumps. The group differences were tested with an analysis of variance. The HT (2.2 Hz) reached a high reproducibility with ICC values >0.97 for K vert. The group of the faster male sprinter demonstrated a shorter contact time, higher frequency with comparable flight time during sprint, a higher K vert during HT as well as a higher jump height during DJ, but only a jump height difference of 3 cm during CMJ. The female sprinters realized a lower K vert as the male athletes. Differences of K vert could be tested reliable by means of HT. K vert and the DJ height differentiated between the male groups with different sprint speed (10.04 vs. 9.19 m/s), but not the CMJ height.