EVIDENCE FOR THE EXISTENCE OF A MOVEMENT SIGNATURE IN SPORT

The purpose of this study was to investigate whether consistent kinematic characteristics exist that enable perceptual categorisation and recognition of movement. Two forms of point-light presentation were employed, a person wearing black clothing in a blackened environment with the joints marked by reflective tape (RT) and a second presentation where the body and background were removed completely and the joints represented by a blue dot (801 or 802). The results of experiment 1 showed the blue dot presentation elicited more correct answers than the RT presentation (p = .005). The blackened background showed some environmental cues in addition to the point-light data, which may have had a distraction effect. Consequently a second experiment was conducted to confirm the differences in the two methods and control for any possible order of presentation. The results stlowed the BD presentation was superior for recognition of consistent kinematic characteristics in randomised presentations (p = .000)

The impact of tool selection on back and wrist injury risk in tying steel reinforcement bars: a single case experiment

The paper explores the risk of work-related musculoskeletal injury in tying steel reinforcement bars. Three tools are compared to determine the extent to which ergonomic tools can reduce the risk of injury to the back and wrist in steel-tying. A whole body system of wearable sensors was used to measure biomechanical risk in tying. Three tools were assessed to determine their impact on the risk of work-related musculoskeletal injury when used at different heights. These were: a conventional pincer-cutting tool; a power-driven tying tool, and a long handled stapler tool. No tool was found to work best in all situations. The long handled stapler tool significantly reduced trunk inclination when used from ground to shoulder height, but produced higher trunk extension (backward bending) when used above shoulder height. The power tying tool did not reduce the need to bend when working at lower work heights. The power-tying tool produced significantly lower peak wrist flexion values compared to the conventional pincer-cutter tool at all work heights except overhead. The power tying tool involved significantly lower levels of wrist rotation than the conventional pincer-cutter tool at all work heights above knee level. Many assessments of ergonomic risk factors in construction rely on observational methods. The use of small, lightweight wearable sensors permits the objective measurement of biomechanical risk factors for work-related musculoskeletal injury, as well as providing objective performance data that can be used in the design and selection of task-specific tools. Our analysis of work by height also provides insight into the way in which risk factors and reduction opportunities afforded by different tools vary depending on the height at which work is to be performed

THE EFFECT OF CLUB DRIVER LENGTH UPON HIP, SHOULDER AND PELVIC MOTION IN GOLF

The aim of this study was to examine the hip, shoulder and pelvic motion elicited by differing lengths of a golf driver (standard and overlength). Seven male golfers with a handicap ranging from 11 to 14 participated in the study. Clubs were fitted to each player and involved a standard length driver and an overlength driver that was 2 inches longer. A preliminary analysis of the data found no significant differences in the hip, shoulder and pelvic motion. Trunk lean, however, was found to be greater with the standard driver for the majority of the swing. This suggests that differences in the shaft length of a driver affects the motion of the trunk and spine

THE ECOLOGICAL VALIDITY OF INJURY PREVENTION SCREENINGMEASURES USED TO IDENTIFY PELVIC INSTABILITY IN ELITE MALE SPRINTERS

The purpose of this study was to ascertain the ecological validity of clinical measures of pelvic stability currently used in injury prevention programs with elite sprinters. Fifteen elite male sprinters of National level participated in this study. Each participant completed 3 trials for two clinical measures of pelvic stability, the standing hip f1exion and dip tests, followed by 3 maximal sprints. A significant moderate correlation coefficient (r =.46, P < .05) was found between the pelvic list data for the hip f1exion test and the pelvic list data for sprinting. Weak non-significant correlation coefficients (r < .23), however, were found for the remaining data. These findings suggest the current clinical measures of pelvic stability may not be ecologically valid

MEASUREMENT ERROR IN SIMULATED 20 GAIT DATA EXTRACTED BY A VIDEO-BASED MOTION MEASUREMENT SYSTEM

An instrument reliability study was conducted in order to quantify the measurement error contained in 2D spatial data (linear and angular) commonly collected in gait and long jump studies (e.g. footfall position, toe-board-distance or limb orientation) by video-based motion measurement systems. Three experiments examined the effect of camera-to-object distance (5 to 10 m) and field of view (2.5 to 4.5 m) upon marker sets (stationary) representative of walking or running motion. The results show 7 to 10 m camera-to-object distances to be associated with the least error (mean absolute error = 0.59 cm) or about a third of the error found for the 5 m distance (mean absolute error = 1.5 cm). No systematic changes in measurement error were found across the differing camera fields of view with the mean absolute error falling below 0.66 cm and 0.6

The impact of tool selection on back and wrist injury risk in tying steel reinforcement bars: a single case experiment

The paper explores the risk of work-related musculoskeletal injury in tying steel reinforcement bars. Three tools are compared to determine the extent to which ergonomic tools can reduce the risk of injury to the back and wrist in steel-tying. A whole body system of wearable sensors was used to measure biomechanical risk in tying. Three tools were assessed to determine their impact on the risk of work-related musculoskeletal injury when used at different heights. These were: a conventional pincer-cutting tool; a power-driven tying tool, and a long handled stapler tool. No tool was found to work best in all situations. The long handled stapler tool significantly reduced trunk inclination when used from ground to shoulder height, but produced higher trunk extension (backward bending) when used above shoulder height. The power tying tool did not reduce the need to bend when working at lower work heights. The power-tying tool produced significantly lower peak wrist flexion values compared to the conventional pincer-cutter tool at all work heights except overhead. The power tying tool involved significantly lower levels of wrist rotation than the conventional pincer-cutter tool at all work heights above knee level. Many assessments of ergonomic risk factors in construction rely on observational methods. The use of small, lightweight wearable sensors permits the objective measurement of biomechanical risk factors for work-related musculoskeletal injury, as well as providing objective performance data that can be used in the design and selection of task-specific tools. Our analysis of work by height also provides insight into the way in which risk factors and reduction opportunities afforded by different tools vary depending on the height at which work is to be performed

TIMING ERROR BY CHILDREN IDENTIFIED WITH DCD LEADS TO INEFFICIENT JUMP PERFORMANCE

The aim of this study was to identify outcome and response differences in vertical jumping between children typically developing (TD) and those identified with Developmental Coordination Disorder (DCD). Efficient vertical jumping is essential to physical activity in children. The TD group jumped higher as a result of a faster vertical velocity of the centre of mass (VCOM) at take-off. Peak VCOM was greater and occurred closer to take-off in TD when compared to DCD. Earlier occurrence of peak VCOM observed in DCD caused a noticeable loss of VCOM at take-off compared to TD. The timing of the peak VCOM before take-off resulted in large group variation for DCD (CV = 50%) compared to the stereotyped TD (CV = 6%). The difference between groups emphasises coordination difficulties of DCD during vertical jumping

ACCURACY OF THE POSITIONAL ACTIVITY LOGGER#2 (PAL2) TO IDENTIFY HUMAN POSTURE AND MOVEMENT

This study investigated the accuracy of the Positional Activity Logger 2 (PAL2, ProMed Pty Ltd) to identify activity. Eighteen healthy adults participated in this study. Activities were performed three times in random order for durations ranging from 10 to 110 s and were simultaneously recorded by a PAL2 (10 Hz) and Vicon System (120 Hz). The PAL2 correctly identified all activities. Significant duration differences were found for lying, running, sitting and standing (p=0.001). No significant duration differences were found for walking. Mean absolute errors ranged from 3.27 to 5.40 s. The validity of the PAL2 was also assessed with ICCs. It was found to be high for lying and running (ICC=0.87, ICC=0.94, p=0.0001), good for sitting and standing (ICC=0.74, ICC=0.76, p=0.0001) yet low for walking (ICC=0.58, p=0.001). Overall, the PAL2 exhibited good accuracy

Efficacy of Vibration Exercise as a Warm-up Modality for Overground Sprinting

International Journal of Exercise Science 8(4): 385-393, 2015. This study investigated the efficacy of vibration exercise (VbX) as a warm-up modality for maximal overground sprinting. Ten national level sprinters participated in a randomized crossover design (14.0 ± 7.4 days washout period). A VbX warm-up was compared to a warm-up involving sprint-specific exercises (control condition). The VbX warm-up involved 10 ´ 1 minute bouts delivered by a Galileo 900 side-alternating plate (frequency = 26 Hz, peak-to-peak displacement = 9 mm) with 30 s rest between bouts (total time = 15 minutes). The sprint-specific warm-up involved jogging, dynamic exercises and sprinting drills followed by 3 ´ 40 m sub-maximal sprints not exceeding 95% of maximal speed over a 15 minute period. After each warm-up (within 2 minutes), 6 ´ 40 m maximum sprints were completed from a crouch start position with starting blocks. Outcome measures were recorded by timing gates (Swift Performance, Australia) and a Vicon Motion Measurement System (Oxford, UK). Measures recorded were sprint time over the 0-4 m, 5-10 m, 10-20 m, 20-40 m and 5-40 m intervals. The stride length, stride velocity and stride time of both legs were recorded over the 0-4 m interval by the Vicon system. All measures remained unchanged across warm-up modalities. It is reasonable to conclude that VbX may be used as an alternative warm-up for sprinting over 40 m. Given its time efficiency and suggested relatively low metabolic cost, VbX may be a suitable warm-up for activities requiring multiple sprints over a competition day or game period

The effect of muscle fatigue on the last stride before stepping down a curb

The stride before landing may be important during stepping down. The aim of this study was to analyze variability of the kinematics and muscle activity in the final stride before stepping down a curb, with and without ankle and knee muscle fatigue. Ten young participants walked at self-selected speed and stepped down a height difference (10-cm) in ongoing gait. Five trials were performed before and after a muscle fatigue protocol (one day: ankle muscle fatigue, another day: knee muscle fatigue). The analysis focused on the trailing leg during the last but one and the last step on the higher level. Kinematics and muscle activity were recorded. Fatigue increased variability of foot-step horizontal distance in the last step on the higher level of the trailing limb, as well as in the first steps on the lower level for both limbs. This appeared due to an increase in the range of motion of the knee joint after both fatigue protocols. Participants additionally showed an increased ankle and hip ROM and decreased knee ROM. Our results suggest a loss of control under fatigue reflected in a higher variability of trailing and leading limb-step horizontal distances, with compensatory changes to limit fatigue effects, such as a redistribution of movement over joints. © 2012 Elsevier B.V