A Systematic Review of Lower Limb Asymmetry After Anterior Cruciate Ligament Reconstruction in Adolescent Athletes

Anterior cruciate ligament (ACL) rupture is a common athletic injury in adolescents which typically requires surgery to repair the injured ACL. Despite considerable efforts to improve outcomes, secondary ACL injury is common in athletes who return to sport. One of the main risk factors for secondary ACL injury is asymmetry in landing mechanics. The aim of this systematic review was to identify the common biomechanical asymmetries after ACL reconstruction in adolescents during landing. Sources were identified through searching databases using relevant search terms. Study titles and abstracts were screened using inclusion criteria which resulted in 13 articles being selected for further analysis. The methodological quality of each study was assessed independently by three reviewers. Asymmetry was more commonly identified in kinetic variables than kinematic variables. The most common asymmetries identified were peak knee extension moment and peak vertical GRF, both of which were frequently shown to be significantly lower in the surgical limb compared to the uninjured limb. These findings suggest that return to sport criteria following ACL reconstruction should incorporate analysis of the asymmetry in loading experienced by each limb rather than examining movement patterns alone

Gender difference in lower limb muscle activity during landing and rapid change of direction

Date of Acceptance: 25/02/2015Surface electromyography (EMG) of the rectus femoris, biceps femoris and gluteus maximus were recorded for 10 male and 10 female basketball, volleyball or netball players performing five repetitions each of two tasks; (1) landing from a maximal height vertical jump and, (2) 45° rapid change of direction on their dominant leg. Independent sample t-tests were conducted to determine sex differences and paired samples t-tests were conducted to determine task differences in peak EMG muscle activityPeer reviewe

The effects of bag style on muscle activity of the trapezius, erector spinae and latissimus dorsi during walking in female university students

© by The Author(s). This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License. (CC BY-NC-ND 3.0)Back pain is common in adolescents which has been associated with carrying a bag. However, there is little research examining the effects of bag style in female adolescents. The aim of the study was to investigate the effects of different bag conditions on muscle activity of the trapezius, erector spinae and latissimus dorsi muscles in female university students during walking. Twelve female university students walked on a treadmill for 5 minutes at 1.1 m/s during five conditions; control, 1 strapped rucksack, 2 strapped rucksack, ipsilateral shoulder strap and contralateral shoulder strap, each containing 10% bodyweight. Electromyography for the trapezius, erector spinae and latissimus dorsi was recorded for the last 30 s of each condition. Two-way ANOVA and paired t-tests were used to identify differences between right and left muscles and between bag conditions. Results showed that muscle activity of the left trapezius was significantly higher than the right trapezius during the 1 strap rucksack condition. For the left trapezius, the 2 strapped rucksack and the control condition had significantly lower muscle activity compared to the 1 strapped rucksack and the ipsilateral shoulder strap. For the left erector spinae muscle, there was significantly greater muscle activity when wearing the contralateral shoulder strap compared to the control. For the right erector spinae, significantly lower muscle activity was observed when wearing the 2 strapped rucksack compared to the ipsilateral shoulder strap and contralateral shoulder strap. There were no significant differences in muscle activity of the latissimus dorsi muscles between any of the bag conditions. These findings suggest that a two strapped rucksack should be used when carrying loads to reduce spinal muscle activity which may, in turn, reduce reports of back pain in female adolescentPeer reviewedFinal Published versio

Reliability of an experimental method to analyse the impact point on a golf ball during putting

This study aimed to examine the reliability of an experimental method identifying the location of the impact point on a golf ball during putting. Forty trials were completed using a mechanical putting robot set to reproduce a putt of 3.2 m, with four different putter-ball combinations. After locating the centre of the dimple pattern (centroid) the following variables were tested; distance of the impact point from the centroid, angle of the impact point from the centroid and distance of the impact point from the centroid derived from the X, Y coordinates. Good to excellent reliability was demonstrated in all impact variables reflected in very strong relative (ICC = 0.98–1.00) and absolute reliability (SEM% = 0.9–4.3%). The highest SEM% observed was 7% for the angle of the impact point from the centroid. In conclusion, the experimental method was shown to be reliable at locating the centroid location of a golf ball, therefore allowing for the identification of the point of impact with the putter head and is suitable for use in subsequent studies

EFFECTS OF FOOTWEAR ON SAGITTAL PLANE KINEMATICS AND CENTRE OF PRESSURE EXCURSION DURING THE BARBELL BACK SQUAT

Footwear has been proposed to alter squat performance whereby flat soles may reduce footfloor proprioception and raised heels may decrease joint range of motion. This study aimed to investigate the effects of footwear on centre of pressure excursion (CPE) and sagittal plane kinematics during the back squat. Seven males performed squats during five different footwear conditions (barefoot, weightlifting shoe, running shoe, minimal shoe, flat-soled shoe) while sagittal plane kinematics and CPE were recorded. Results showed no significant difference in CPE between any footwear conditions. Peak knee flexion was significantly greater for running shoes and weightlifting shoes compared to barefoot. Peak shank angle was significantly greater when wearing weightlifting shoes compared to minimal footwear. This suggests footwear which increases heel height may increase peak joint angles to allow for a deeper squat

The effect of movement variability on putting proficiency during the golf putting stroke

Movement variability has been considered important to execute an effective golf swing yet is comparatively unexplored regarding the golf putt. Movement variability could potentially be important considering the small margins of error between a successful and a missed putt. The aim of this study was to assess whether variability of body segment rotations influence putting performance (ball kinematic measures). Eight golfers (handicap range 0–10) performed a 3.2 m level putt wearing retro-reflective markers which were tracked using a three-dimensional motion analysis system sampling at 120 Hz. Ball roll kinematics were recorded using Quintic Ball Roll launch monitor. Movement (segment) variability was calculated based on a scalene ellipsoid volume concept and correlated with the coefficient of variation of ball kinematics. Statistical analysis showed no significant relationships between segment variability and putting proficiency. One significant relationship was identified between left forearm variability and horizontal launch angle, but this did not result in deficits in putting success. Results show that performance variability in the backswing and downswing is not related to putting proficiency or the majority of ball roll measures. Differing strategies may exist where certain golfers may have more fluid movement patterns thereby effectively utilising variability of movement. Therefore, golf instructors should consider movement variability when coaching the golf putt

Gender differences in intra-limb coordination during single limb landings on dominant and non-dominant legs

This study investigated the effects of gender and landing limb on intra-limb coordination during single limb drop landings. Fourteen females and eight males performed drop landings while lower limb kinematics were recorded in the sagittal plane. Discrete relative phase (DRP) and standard deviation of DRP were calculated for hip-knee, knee ankle and hip-ankle joint couplings. Mixed between-within ANOVA showed no significant gender effects for DRP of joint couplings (p > 0.05). Females showed significantly greater standard deviation of DRP for the hip-knee (p = 0.03) and hip-ankle (p = 0.04) joint couplings. There were no significant effects for limb in DRP of joint couplings (p > 0.05). Knee-angle standard deviation of DRP was significantly greater for the dominant limb compared to the non-dominant limb (p = 0.04). These findings suggest males and females adopt similar intra-limb coordination strategies when landing, however, females exhibit greater variability in coordination which may indicate greater adaptation in coordination patterns in an attempt to mitigate the effects of fatigue or compensate for gender differences in landing kinematics and kinetics identified in previous research

THE EFFECT OF UPPER LIMB POST-ACTIVATION POTENTIATION ON INCREASES IN VERTICAL JUMP HEIGHT DUE TO AN ARM SWING

Post-activation potentiation (PAP) refers to the phenomenon where muscular performance is improved as a result of contractile history. The aim of this study was to investigate the effects of upper limb PAP on vertical jumping. Firstly, countermovement jumps were performed with (CMJAS) and without an arm swing (CMJ). Participants then carried out 10 dumbbell swings with a weight of 15% of the participant’s body weight and performed further countermovement jumps with an arm swing at 3 (PAP3mins), 6 (PAP6mins) and 9 (PAP9mins) minute rest periods. There was a significant difference (p \u3c 0.05) in jump height, peak vertical GRF and peak concentric power when comparing CMJ to CMJAS. No significant difference was found when comparing a CMJAS to any of the conditions with induced PAP on the upper limbs. This indicates that inducing PAP on the upper limbs does not have a significant effect on jump height