This study aimed to compare the angle-specific (AS) and non-angle-specific (NAS) hamstring to quadriceps conventional and functional ratios between healthy, hamstring- and ACL-injured elite soccer players. One hundred and eleven players (27.42 ± 8.01 years, 182.11 ± 6.79 cm, 75.93 ± 7.25 kg) completed a series of concentric knee flexor and extensor strength in addition to eccentric knee flexor strength was measured at an angular velocity of 60°.s-1. Normalized and raw peak torque values, and the torque-angle profiles were extracted for analysis. Conventional and functional NAS (peak values) and AS (waveform ratios) hamstring to quadriceps ratios were calculated and compared between the groups. Healthy players produced greater functional and conventional ratios compared to players with either ACL or hamstring injury. Players with hamstring injury produced a lower AS functional ratios between 46° and 54° of knee flexion. Players suffering from ACL injury depicted a lower value for the AS functional ratio between 33° and 56° of knee flexion. Although NAS can identify soccer players with previous hamstring or ACL injury, the range where there is a strength deficiency is eluded. With the use of AS the range where the deficiency is present can be identified, and clinicians can benefit from this analysis to design robust rehabilitation protocols.
Mobile phone use affects the dynamics of gait by impairing visual control of the surrounding environment and introducing additional cognitive demands. Although it has been shown that using a mobile phone alters whole-body dynamic stability, no clear information exists on its impacts on motor variability during gait. This study aimed at assessing the impacts of various types of mobile phone use on motor variability during gait; quantified using the short- and long-term Lyapunov Exponent (λS and λL) of lower limb joint angles and muscle activation patterns, as well as the centre of mass position. Fourteen females and Fifteen males (27.72 ± 4.61 years, body mass: 70.24 ± 14.13 Kg, height: 173.31 ± 10.97 cm) walked on a treadmill under six conditions: normal walking, normal walking in low-light, walking while looking at the phone, walking while looking at the phone in low-light, walking and talking on the phone, and walking and listening to music. Variability of the hip (p λS = .015, λL = .043) and pelvis (p λS = .039, λL = .017) joint sagittal angles significantly increased when the participants walked and looked at the phone, either in normal or in low-light conditions. No significant difference was observed in the variability of the centre of mass position and muscle activation patterns. When individuals walk and look at the phone screen, the hip and knee joints are constantly trying to adopt a new angle to regulate and maintain gait stability, which might put an additional strain on the neuromuscular system. To this end, it is recommended not to look at the mobile phone screen while walking, particularly in public places with higher risks of falls.
Background: Stability is one of the key demands in human locomotion including running. Various kinematical analytical approaches are adopted to investigate the running strategies; nevertheless, the impacts of running speeds on the variability of angles in individual lower limbs joints is still unclear. Objective: This study was aimed to investigate the impact of various running speeds on linear and non-linear variability of the hip, knee and ankle joints movement. Methods: Twenty-three collegiate athletes (13 females, 10 males, age 22.04 ± 3.43 years, body mass 62.14 ± 9.26 kg, height 168.29 ± 7.06 cm) ran at preferred running speed, 20% lower, and 20% higher than preferred running speed on a treadmill and their lower limbs joints kinematics were recorded using myoMOTION system at the sampling frequency of 200 Hz. The repeated measure analysis of variance test was adopted to investigate the linear (mean and standard deviation) and non-linear (Lyapunov exponent) variability of the hip, knee and ankle angle in sagittal, frontal and transverse planes throughout the running cycle. Results: No significant difference was observed between the lower limbs joint angles variability in linear analysis, while the Lyapunov exponent of the hip (p = .008, ηp2 = .338), knee (p = .002, ηp2 = .249) joints in the sagittal plane significantly increased as running speed increased. Conclusions: Findings of this study revealed that the hip and knee joints respond with more freedom of movement in the sagittal plane while walking speed increases, although nonlinear approaches were the only ones capable of detecting it. Given that speed changes might reduce body stability, it appears that these joints are attempting to maintain body stability by regulating internal body system perturbations by increasing their variability.
- Klíčová slova
- Lyapunův exponent,
- MeSH
- běh * fyziologie MeSH
- biomechanika MeSH
- lidé MeSH
- výzkum MeSH
- Check Tag
- lidé MeSH
This study investigated the whole-body coordination patterning in successful and faulty spikes using self-organising map-based cluster analysis. Ten young, elite volleyball players (aged 15.5 ± 0.7 years) performed 60 volleyball spikes in a real-game environment. Adopting the cluster analysis, based on a self-organising map, whole-body coordination patterning was explored between successful and faulty spikes of individual players. The self-organising maps (SOMs) portrayed whole body, lower and upper limb coordination dissimilarities during the jump phase and the ball impact phases between the successful and faulty spikes. The cluster analysis illustrated that the whole body, upper limb and lower limb coordination patterning of each individual's successful spikes were similar to their faulty spikes. Range of motion patterning also demonstrated no differences in kinematics between spike outcomes. Further, the upper limb angular velocity patterning of the players' successful/faulty spikes were similar. The SPM analysis portrayed significant differences between the normalized upper limb angular velocities from 35% to 45% and from 76% to 100% of the spike movement. Although the lower limb angular velocities are vital for achieving higher jumps in volleyball spikes, the results of this study portrayed that the upper limb angular velocities distinguish the differences between successful and faulty spikes among the attackers. This confirms the fact that volleyball coaches should shift their focus toward the upper limb velocity and coordination training for higher success rates in spiking for volleyball attackers.
- MeSH
- biomechanika MeSH
- dolní končetina MeSH
- lidé MeSH
- mladiství MeSH
- pohyb MeSH
- rozsah kloubních pohybů MeSH
- shluková analýza MeSH
- sportovní výkon * MeSH
- volejbal * MeSH
- Check Tag
- lidé MeSH
- mladiství MeSH
- Publikační typ
- časopisecké články MeSH
