Purpose Foot strike patterns (FSP) influence landing mechanics, with rearfoot strike (RFS) runners exhibiting higher impact loading than forefoot strike (FFS) runners. The few studies that included midfoot strike (MFS) runners have typically grouped them together with FFS. In addition, most running studies have been conducted in laboratories. Advances in wearable technology now allow the measurement of runners’ mechanics in their natural environment. The purpose of this study was to examine the relationship between FSP and impacts across a marathon race. Methods A total of 222 healthy runners (119 males, 103 females; age, 44.1 ± 10.8 yr) running a marathon race were included. A treadmill assessment was undertaken to determine FSP. An ankle-mounted accelerometer recorded tibial shock (TS) over the course of the marathon. TS was compared between RFS, MFS, and FFS. Correlations between speed and impacts were examined between FSP. TS was also compared at the 10- and 40-km race points. Results RFS and MFS runners exhibited similar TS (12.24g ± 3.59g vs 11.82g ± 2.68g, P = 0.46) that was significantly higher (P < 0.001 and P < 0.01, respectively) than FFS runners (9.88g ± 2.51g). In addition, TS increased with speed for both RFS (r = 0.54, P = 0.01) and MFS (r = 0.42, P = 0.02) runners, but not FFS (r = 0.05, P = 0.83). Finally, both speed (P < 0.001) and TS (P < 0.001) were reduced between the 10- and the 40-km race points. However, when normalized for speed, TS was not different (P = 0.84). Conclusions RFS and MFS exhibit higher TS than FFS. In addition, RFS and MFS increase TS with speed, whereas FFS do not. These results suggest that the impact loading of MFS is more like RFS than FFS. Finally, TS, when normalized for speed, is similar between the beginning and the end of the race.

The use of virtual reality (VR) to simulate confrontational human behaviour has signifcant potential for use in training, where the recreation of uncomfortable feelings may help users to prepare for challenging real-life situations. In this paper we present a user study (n=68) in which participants experienced simulated confrontational behaviour performed by a virtual character either in immersive VR, or on a 2D display. Participants reported a higher elevation in anxiety in VR, which correlated positively with a perceived sense of physical space. Character believability was infuenced negatively by visual elements of the simulation, and positively by behavioural

A simple method to quantify the kinematic chain in a propulsive task would facilitate assessment of athlete effectiveness. The study's aim was to assess if the kinematic chain distinguishes between skill levels. Fencers were separated into two groups based on attacking lunge ability (7 skilled; 8 novices). Rear leg 3D joint angular extension velocity magnitudes and timings, sword kinematics and rear leg kinetics were obtained in the propulsion phase of the attacking lunge. Skilled fencers obtained greater sword velocity (3.24 ± 0.24 m•s−1 vs. 2.69 ± 0.29 m•s−1; p = 0.02). The skilled group had a greater sequential kinematic chain of the hip, knee and ankle, demonstrated by significantly greater ankle angular velocity (9.1 ± 2.1 rad·s−1 skilled; 5.4 ± 2.9 rad·s−1 novice). Ankle plantarflexion velocity showed a strong positive correlation with horizontal peak force (r = 0.81; p < 0.01). The skilled group demonstrated greater horizontal impulse (1.85 ± 0.29 N·s·kg−1 skilled; 1.45 ± 0.32 N·s·kg−1 novice), suggesting greater effectiveness in applying the kinematic chain towards horizontal propulsion. Analysis of the kinematic chain, which was able to distinguish between skill levels in a propulsive task, is an effective and simple paradigm to assess whole limb contributions to propulsive movements.

Biofeedback (BFb) can enhance the motor learning process by guiding skill exploration. Too much BFb, however, can foster dependency leading to skill retention deficits once removed. A reducing BFb schedule could negate dependency effects, however limited methodologies exist to assess the effectiveness of an intervention during application. This research proposes a new bi-variate method (CI2Area) to quantify coordination variability (CoordVar) as a measure of skill exploration during a motor learning intervention. Thirty-two participants were introduced to a novel explosivelunge task. A BFb group (n=16) were provided with visual BFb on rear hip, knee and ankle joint extension magnitudes and timing during a 26-week reducing schedule BFb intervention. CoordVar of hip-knee and knee-ankle angular velocities were quantified by calculating the area encompassed by the 95% confidence intervals of joint coupling angular-velocity bi-variate plots (CI2Area). Linear regressions were fitted to group and individual CoordVar longitudinal data. The BFb was effective in successfully altering whole limb technique within just two sessions, and these changes were retained. The BFb group demonstrated a continual increase of CoordVar throughout the intervention, showing continual skill exploration strategies, while the Control group remained unchanged. Gradually increasing time between sessions, using a longitudinally reducing BFb schedule, successfully negates dependency effects on BFb while also encouraging motor learning. Manipulating time between sessions allows for the provision of a high frequency of 100% BFb without fostering dependency. The CI2Area method was able to detect individual exploration strategies and could be used in the future to direct individual intervention modifications.

This study investigated overarm throwing technique at different developmental ages in children from the perspective of three distinct, though potentially complementary, approaches to motor skill acquisition. Children at 6, 10, and 14 years of age (N = 18), completed dominant overarm throws during which whole-body kinematic data were collected. Firstly, application of Newell's (1985) stages of learning identified three distinct age-related coupling modes between forward motion of the centre-of-mass (CoM) and the wrist, which demonstrated a greater range of couplings for older children. Secondly, in line with Bernstein's (1967) hypothesis of freezing before freeing degrees of freedom, a significantly smaller range of motion (ROM) at the ankle and knee joints, but greater ROM at the hip and upper limb joints was found for the 6 year old group compared to the 10 and 14 year old groups. Thirdly, based on the components model (Roberton & Halverson, 1984), the overarm throws demonstrated by 6 year olds were characterised as primitive to intermediate, where 10 and 14 year old's throws were characterised by the penultimate action level for each component. Characteristics of CoM-wrist coupling more clearly identify children's age-related technique and highlight the importance of posture-ball release dynamics. The posture-ball dynamics were supported by changes in ROM and the components model, revealing the complementary nature of the 3 approaches to the analysis of age-related differences in overarm throwing action.