This study investigated the relationship between isokinetic muscle strength metrics, landing biomechanics, and their asymmetries, in females. Twenty-three female team sport athletes completed unilateral forward drop landings, and isokinetic muscle strength assessment of the knee extensors and flexors, on both limbs. Discrete two-dimensional kinematics of the trunk, hip, knee, and ankle in the sagittal and frontal plane and peak GRF were recorded during the drop landings. Novel, task-specific isokinetic strength metrics related to the landing task, such as peak concentric and eccentric torque, angle specific torque (AST), functional range and traditional/functional ratios were quantified. Asymmetry for kinematic and muscle strength data were quantified based on the individual variability of the task and the population mean and smallest worthwhile change. Functional concentric flexor range explained 15-18% of the variance in peak frontal trunk (P = 0.003) and hip motion (P = 0.007) and 22% in peak frontal knee motion (P = 0.005), when combined with the functional flexion ratio. Peak eccentric extensor torque explained 13-14% of the variance in peak sagittal hip (P = 0.014) and knee (P = 0.009) motion. Asymmetry in concentric extensor AST explained 28% of the variance in peak knee frontal plane asymmetry (P = 0.010), however the direction of asymmetry was rarely present on the same side for kinematic and strength variables. Novel and task specific isokinetic strength metrics explained small but significant variances in sagittal and frontal plane landing kinematics and asymmetry, which have previously been related to ACL injury risk.

The effect of exercise-induced muscle damage (EIMD) on three-dimensional side cut biomechanics and task achievement were assessed in 16 team sport athletes (eight males and eight females) who completed 45° side cuts before and 48 h after multidirectional running. Angular displacement and joint moments of the hip and knee, and GRF impulse (IGRF) during five successful trials of a 45° side cut, were collected using a 3D motion capture system and force platform at both timepoints. At 48 h, participants had more knee internal rotation (p = 0.009), knee abduction ROM (p = 0.002), lower peak knee extensor moment (p = 0.001) and a higher hip-knee extensor ratio moment (p = 0.020). Large increases in IGRF at 48 h in females (d; ± 95% CI: 1.4; ± 1.4, p = 0.037) suggest a less effective deceleration capacity. Whilst EIMD had no effect on side cut task achievement and sagittal kinematics, EIMD caused participants to shift the extensor demands away from the knee and towards the hip to decelerate the body. Practitioners should be mindful of potential increases in frontal and transverse motions at the knee for athletes with EIMD, which might have implications for strategies to reduce injury risk.

The purpose of this study was to examine the efficacy of high friction socks on in-shoe foot sliding and running performance of male footballers during change of direction movements. Twelve recreational football players (mean age 20.3 +/- 1.1 years) completed a 26 m dynamic agility course at their maximum running speed. 3D kinematic and kinetic data were collected for three maximum speed 45 degrees side-cuts, and 180 degrees turns in two different sock conditions. Comparisons were made between a sock with a high static coefficient of friction (GripSock) and a regular sock (CompressionS). The Gripsock condition significantly increased utilized traction (COFu) and a reduction of GRF angle (GRF alpha) was identified during the braking phase of the side cut (COFu: + 9.3 +/- 10%; GRF alpha: -3.1 +/- 2.9%) but not in the side-cut propulsion, turn braking and turn propulsion phases. Speed perception was raised in the GripSock condition (+18 +/- 30%). However, wearing a sock with high frictional properties did not significantly reduce in-shoe foot sliding in any examined direction nor did it significantly reduce running times over a functional traction course. The relationship between in-shoe traction and running performance is complex and likely dependent on the overall interaction of shoe properties and the type of athletic sock.

Purpose: We examined the movement, physiological and muscle function responses to running with and without (i.e. linear) multiple directional changes to understand which measures of external demands better reflected changes in the internal response. Methods: Twelve team sport athletes completed a linear and multidirectional running trial during which movement characteristics, oxygen consumption (V˙O2), blood lactate (B[La]) and heart rate (HR) were measured. Isometric peak torque of knee extensors and flexors was also assessed before and after each trial. Results: High speed running distance was higher during the linear trial (p < 0.001), whereas time at high metabolic power (p = 0.046), number of accelerations (p < 0.001), summated HR (p = 0.003) and B[La] (p = 0.002) were higher during the multidirectional trial. Integrated external to internal ratios of high-speed running: summated HR and high-speed running: total V˙O2 were different between multidirectional and linear trials (p ≤ 0.001). Conversely, high metabolic power: summated HR and high metabolic power: total V˙O2 were similar (p ≥ 0.246). Small decrements in knee flexor (p = 0.003) and extensor torque (p = 0.004) were observed after both trials. Conclusion: Time at high metabolic power better reflects the increased internal response during running with more directional changes than high speed running.

Objectives: To assess the effect of a home-based over-ground robotic-assisted gait training program using the AlterG Bionic Leg orthosis on clinical functional outcomes in people with chronic stroke. Design: Randomized controlled trial. Setting: Home. Participants: Thirty-four ambulatory chronic stroke patients who recieve usual physiotherapy. Intervention: Usual physiotherapy plus either (1)10-week over-ground robotic-assisted gait training program (n = 16), using the device for ⩾30 minutes per day, or (2) control group (n = 18), 30 minutes of physical activity per day. Measurements: The primary outcome was the Six-Minute Walk Test. Secondary outcomes included: Timed-Up-and-Go, Functional Ambulation Categories, Dynamic Gait Index and Berg Balance Scale. Physical activity and sedentary time were assessed using accelerometry. All measurements were completed at baseline, 10 and 22 weeks after baseline. Results: Significant increases in walking distance were observed for the Six-Minute Walk Test between baseline and 10 weeks for over-ground robotic-assisted gait training (135 ± 81 m vs 158 ± 93 m, respectively; P ⩽ 0.001) but not for control (122 ± 92 m vs 119 ± 84 m, respectively). Findings were similar for Functional Ambulation Categories, Dynamic Gait Index and Berg Balance Scale (all P ⩽ 0.01). For over-ground robotic-assisted gait training, there were increases in time spent stepping, number of steps taken, number of sit-to-stand transitions, and reductions in time spent sitting/supine between baseline and 10 weeks (all P < 0.05). The differences observed in all of the aforementioned outcome measures were maintained at 22 weeks, 12 weeks after completing the intervention (all P > 0.05). Conclusion: Over-ground robotic-assisted gait training combined with physiotherapy in chronic stroke patients led to significant improvements in clinical functional outcomes and physical activity compared to the control group. Improvements were maintained at 22 weeks.

Stroke is a major global health problem whereby many survivors have unmet needs concerning mobility during recovery. As such, the use of robotic-assisted devices (i.e., a bionic leg) within a community setting may be an important adjunct to normal physiotherapy in chronic stroke survivors. This study will be a dual-center, randomized, parallel group clinical trial to investigate the impact of a community-based training program using a bionic leg on biomechanical, cardiovascular, and functional outcomes in stroke survivors. Following a baseline assessment that will assess gait, postural sway, vascular health (blood pressure, arterial stiffness), and functional outcomes (6-minute walk), participants will be randomized to a 10-week program group, incorporating (1) a physiotherapy plus community-based bionic leg training program; (2) physiotherapy only; or (3) usual care control. The training program will involve participants engaging in a minimum of 1 hour per day of bionic leg activities at home. Follow-up assessments, identical to baseline, will occur after 10 weeks, and 3 and 12 months postintervention. Given the practical implications of the study, the clinical significance of using the bionic leg will be assessed for each outcome variable. The potential improvements in gait, balance, vascular health, and functional status may have a meaningful impact on patients' quality of life. The integration of robotic devices within home-based rehabilitation programs may prove to be a cost-effective, practical, and beneficial resource for stroke survivors.

The purpose of this study was to quantify the 3D kinetics and kinematics of six punch types among amateur boxers. Fifteen males (age: 24.9 +/- 4.2years; stature: 1.78 +/- 0.1m; body mass: 75.3 +/- 13.4kg; boxing experience: 6.3 +/- 2.8years) performed maximal effort punches against a suspended punch bag during which upper body kinematics were assessed via a 3D motion capture system, and ground reaction forces (GRF) of the lead and rear legs via two force plates. For all variables except elbow-joint angular velocity, analysis revealed significant (P<0.05) differences between straight, hook and uppercut punches. The lead hook exhibited the greatest peak fist velocity (11.95 +/- 1.84m/s), the jab the shortest delivery time (405 +/- 0.15ms), the rear uppercut the greatest shoulder-joint angular velocity (1069.8 +/- 104.5 degrees/s), and the lead uppercut the greatest elbow angular velocity (651.0 +/- 357.5 degrees/s). Peak resultant GRF differed significantly (P<0.05) between rear and lead legs for the jab punch only. Whilst these findings provide novel descriptive data for coaches and boxers, future research should examine if physical and physiological capabilities relate to the key biomechanical qualities associated with maximal punching performance.

There is evidence that increasing the longitudinal bending stiffness of sprinting footwear can lead to improved sprinting performance although this has not yet been established. This study examined the effect of four known shoe stiffness conditions on both sprinting performance and metatarsophalangeal joint (MTPJ) motion. Twelve trained sprinters performed 40 m maximal sprints along an indoor running track, two sprints in each stiffness condition, and high-speed video (600 Hz) recorded two-dimensional MTPJ motion during ground contact. To explore individual responses to the footwear manipulations, three-dimensional (1000 Hz) kinematic and kinetic data were collected during maximal sprinting for two sprinters. At the group-level, increasing shoe bending stiffness elicited no significant differences in sprinting performance or MTPJ motion, with any changes between conditions being subject-specific. In-depth individual analyses revealed that increased shoe stiffness could restrict motion about the MTPJ and there appeared to be a preferred stiffness for best performance. This notion of individual optimal sprint shoe stiffness and what factors might contribute to the optimum requires further investigation.

The metatarsophalangeal joint is an important contributor to lower limb energetics during sprint running. This study compared the kinematics, kinetics and energetics of the metatarsophalangeal joint during sprinting barefoot and wearing standardized sprint spikes. The aim of this investigation was to determine whether standard sprinting footwear alters the natural motion and function of the metatarsophalangeal joint exhibited during barefoot sprint running. Eight trained sprinters performed maximal sprints along a runway, four sprints in each condition. Three-dimensional high-speed (1000 Hz) kinematic and kinetic data were collected at the 20 m point. Joint angle, angular velocity, moment, power and energy were calculated for the metatarsophalangeal joint. Sprint spikes significantly increase sprinting velocity (0.3 m/s average increase), yet limit the range of motion about the metatarsophalangeal joint (17.9% average reduction) and reduce peak dorsiflexion velocity (25.5% average reduction), thus exhibiting a controlling affect over the natural behavior of the foot. However, sprint spikes improve metatarsophalangeal joint kinetics by significantly increasing the peak metatarsophalangeal joint moment (15% average increase) and total energy generated during the important push-off phase (0.5 J to 1.4 J). The results demonstrate substantial changes in metatarsophalangeal function and potential improvements in performance-related parameters due to footwear.

The metatarsophalangeal joint (MPJ) is a significant absorber of energy in sprinting. This study examined the influence of MPJ axis choice and filter cut-off frequency on kinetic variables describing MPJ function during accelerated sprinting. Eight trained sprinters performed maximal sprints along a runway. Three-dimensional high-speed (1000 Hz) kinematic and kinetic data were collected at the 20 m point. Three axis definitions for the five MPJs were compared. MPJ moments, powers and energies were calculated using different filter cut-off frequencies. The more anatomically appropriate dual axis resulted in less energy absorbed at the MPJ compared to the oblique axis which also absorbed less energy compared to the perpendicular axis. Furthermore, a low cut-off frequency (8 Hz) substantially underestimated MPJ kinematics, kinetics and the energy absorbed at the joint and lowered the estimate of energy production during push-off. It is concluded that a better understanding of MPJ function during sprinting would be obtained by using an oblique or anatomically appropriate representation of the joint together with appropriate kinematic data sampling and filtering so that high frequency movement characteristics are retained.