Analysis of Joint Power and Work During Gait in Children With and Without Cerebral Palsy.

Purpose: To compare joint work in the lower limb joints during different sub-phases of the gait cycle between Cerebral Palsy (CP) and healthy children. Methods: Eighteen CP and 20 healthy children's gait data were collected. The CP group included orthoses, intra-muscular injection of botulinum toxin and surgery groups. A motion capture system was used to collect gait data. Joint work was calculated as positive and negative components in six subphases during gait and normalised by speed when comparing the groups. Results: The CP group had a slower walking speed, smaller stride length and longer stance phase than the healthy group. Hip max positive work was 0.12 ± 0.02 Jkg-1/ms-1 for the CP group in pre-mid-stance but 0.07 ± 0.01 Jkg-1/ms-1 for the healthy group during the terminal phase. In terminal stance, ankle positive work was significantly lower in the CP group (0.12 ± 0.01) than in the healthy group (0.18 ± 0.01). The knee showed a similar distribution of positive work in the stance phase for the two groups. In the ankle and hip, the CP group had energy generation mainly in midstance while the healthy group was mainly in terminal stance. In the ankle, the CP group had larger energy absorption in mid-stance than the healthy children group, while the CP group showed lower energy generation in the terminal stance phase than seen in the healthy group. Conclusion: The qualitative and quantitative analysis of joint work provides useful information for clinicians in the treatment and rehabilitation of CP patients.

Analysis of mechanical energy in thigh, calf and foot during gait in children with cerebral palsy.

BACKGROUND: Many studies on children with cerebral palsy (CP) have focused on metabolic energy, however research on the mechanical energy in the lower limbs is sparse. RESEARCH QUESTION: What differences of mechanical energies in the lower limbs exist between the children with CP and typically developing (TD) children during gait? The purpose of this research was to analyse the mechanical energy changes of the lower limbs of children with CP during walking and compare them with TD children. METHODS: Twelve children with CP including 8 diplegic and 4 hemiplegic without severity levels (aged 4-22 year old) and 14 TD participants (aged 5-15 year old) walked barefoot in a gait lab where a motion capture system collected marker data during walking. The translational and rotative kinetic energy and potential energy in the thigh, calf and foot were then calculated using the marker data. Gait parameters, e.g., stride frequency, pace, stride length, stride width, were also obtained. FINDINGS: The results show that the children with CP had significantly lower values than the TD group in terms of kinetic energy and potential energy. This was especially seen in the thigh where the energy recovery coefficient in the children with CP was 31% compared with 43% in the TD group. In the calf and foot, the CP and TD groups had similar energy recovery to the TD group, i.e. not significantly different clinically. The gait parameters showed that children with CP had slower walking speed, shorter stride length, larger step width than TD but similar cadence to TD. INTERPRETATION: The energy recovery coefficient represents the efficiency of exchanges of kinetic and potential energies. The higher its value, the better the energy use during gait. SIGNIFICANCE: This study concluded that CP gait is weaker in the use of energy than TD gait. To our best knowledge, this study is the first one to analyse mechanical energy changes in the lower limbs for CP and TD groups during gait.

Effect of wheelchair configurations on shoulder movements, push rim kinetics and upper limb kinematics while negotiating a speed bump.

This study aimed to provide a comprehensive assessment of upper limb kinetics and kinematics and shoulder movements during wheelchair propulsion while negotiating a speed bump of 6 cm height using four different wheelchair configurations. 16 healthy males aged 30.8 ± 5.7 years participated in the experiment. The kinetic and kinematic data during wheelchair propulsion were recorded. A smart system was used to collect the push forces and a motion capture system was used to collect upper limb movements. The results show that approximately 50% more pushing force was required to negotiate the speed bump than that of level ground propulsion. At the upward-forward axle position, peak total forces were 95.17 ± 5.70 N which resulted in significantly improved propulsion ergonomics, but 129.36 ± 6.68 N was required at the upward-back axle position at the speed bump push. The findings could help manufactures to design protective gloves for wheelchair users and provide useful rehabilitation information to clinicians and patients. Practitioner summary: This study investigated pushing forces and movements during wheelchair propulsion over a speed bump. Approximately 50% more pushing force was required to negotiate the bump than a level surface propulsion. The upper-forward axle position was found to be reasonably better than other positions during wheelchair propulsion. Abbreviations: UF: upper and forward position; UB: upper and back position; DF: down and forward position; DB: down and back position; ROM: range of motion.

Barbell back squat: how do resistance bands affect muscle activation and knee kinematics?

OBJECTIVES: This study aimed to determine whether looped resistance bands affect knee kinematics and lower body muscle activation during the barbell back squat. METHODS: Twenty-six healthy participants (13 female, 13 male) calculated their one repetition maximum (RM) prior to data collection. Each participant performed three squats at both 80% and 40% 1RM wearing a light resistance band, an extra-heavy resistance band and no resistance band.Vicon 3D motion analysis cameras were used to collect the kinematic data, and Delsys Trigno Lab wireless electromyography (EMG) system was used to measure vastus medialis, vastus lateralis, gluteus maximus, gluteus medius and biceps femoris muscle activity. Peak knee flexion angle, peak knee valgus angle and maximum tibial rotation values were examined. Peak EMG values were also analysed after being normalised and expressed as a percentage of maximum voluntary contraction (MVC). RESULTS: Gluteus maximus (GM) activity is significantly increased when a resistance band is used during squatting. However, squatting with a resistance band is detrimental to knee kinematics as it leads to an increase in knee valgus angle and maximum tibial rotation angle. A direct correlation is recorded between an increase in resistance and an increase in these two angles. CONCLUSIONS: Squatting with resistance bands is likely to increase the risk of knee injury. Coaches and clinicians who already implement this technique are advised to remove resistance band squats from training and rehabilitation programmes. Further research evaluating the long-term effects of using resistance bands during the barbell back squat should be considered.

Can foot angle influence the risk of injury to the lower limb joints during a field hockey hit?

OBJECTIVES: The lower limb is widely reported as the most commonly injured body part in the field of hockey, more specifically lateral ankle sprains and internal knee injury. Despite this, there remains limited understanding of how the biomechanics of the sport could be adapted to minimise injury. The aim of this study was to propose a foot position during the hockey hit that results in the smallest joint angles and moments, from a total of four different foot positions: 0°, 30°, 60° and 90°, which may correlate to injury risk. METHOD: Eighteen players from the local University Ladies Hockey Club participated in this study. Each player was required to perform a hit with their lead foot in four different positions: 0°, 30°, 60° and 90°, where 0° was a lead foot position perpendicular to the direction of motion of the ball. Angles and moments were calculated with the Vicon system using force plates and motion analysis. RESULTS: Significant differences (p<0.05) were found between the angles and moments of the four foot positions tested, indicating that foot angle can influence the degree of angulation, and moments, produced in the lower limb joints during the hockey hit. CONCLUSION: There is a relationship between lead foot position and the angles and moments produced in the lower limb joints during the hockey hit, and this may correlate with injury risk.

Effect of ball position on the risk of injury to the lower limb joints during the hockey sweep pass in women.

OBJECTIVES: This study aimed to determine if ball position influences the risk of lower limb non-contact injury in hockey sweep pass. It also aimed to determine a ball position that minimises excessive strain placed on the lower limb joints of the lead leg during the sweep pass. METHODS: A cohort of 18 female hockey-playing volunteers (age: 19.7±1.5 years; height: 165.5±5.4 cm; body mass: 66.4±7.0 kg) were recruited. Participants performed the sweep pass using three different ball positions: in front, in line with, and behind the heel of the lead (left) foot.Motion analysis and force plate data were collected. Moments and angles in all three planes of motion for the three main lower limb joints were then calculated using Vicon software. Results were statistically analysed using SPSS software. RESULTS: Significant differences (p<0.05) were found between the three tested ball positions for the mean maximum angles and moments, and mean ranges of motion produced at the lead three main lower limb joints. Positioning the ball in line with the heel of the lead foot resulted in the lowest moments and angles when compared with the other two ball positions. CONCLUSIONS: The results indicate that positioning the ball in line with the heel of the lead foot is recommended to minimise the risk of injury to the lower limb joints during the hockey sweep pass. It is hoped that these findings will result in this position being implemented by players new to hockey or those returning to the sport following injury.

Establishing state of motion through two-dimensional foot and shoe print analysis: A pilot study.

According to the College of Podiatry, footprints rank among the most frequent forms of evidence found at crime scenes, and the recent ascension of forensic podiatry reflects the importance of footwear and barefoot traces in contemporary forensic practice. In this context, this pilot study focused on whether it is possible to distinguish between walking and running states using parameters derived from two-dimensional foot or shoe prints. Eleven subjects moved along four tracks (barefoot walking; barefoot running; footwear walking; footwear running) while having their bare feet or footwear stained with artificial blood and their footstep patterns recorded. Contact stains and associated bloodstain patterns were collected, and body movements were recorded through three-dimensional motion capture. Barefoot walking prints were found to be larger than barefoot static prints (1.789±0.481cm; p<0.001) and barefoot running prints (0.635±0.405cm; p=0.006). No correlation was observed for footwear prints. Running trials were more associated with the presence of both passive and cast off stains than walking trials, and the quantity of additional associated stains surrounding individual foot and shoe prints was also higher in running states. Furthermore, a previously proposed equation predicted speed with a high degree of accuracy (within 6%) and may be used for clinical assessment of walking speed. Contact stains, associated bloodstain patterns and stride length measurements may serve to ascertain state of motion in real crime scene scenarios, and future studies may be capable of designing statistical frameworks which could be used in courts of law.

A pilot biomechanical assessment of curling deliveries: is toe sliding more likely to cause knee injury than flatfoot sliding?

BACKGROUND: The aim of this study was to determine whether toe sliding is more likely to cause knee injuries than flatfoot sliding in curling. METHODS: Twelve curlers participated in the study, each delivering 12 stones. Six stones per volunteer were delivered using a flatfoot slide and six were delivered using a toe slide. The Pedar-X in-shoe pressure system recorded the plantar pressure during each of the slides, while a sagittal plane digital video recorded the body position of the curler. Measurements were taken from the video recordings using a software overlay program (MB Ruler), and this, combined with the Pedar-X data, gave the overall joint force in the tuck knee. RESULTS: The knee joint force for toe sliding was more than double that of flatfoot sliding (p<0.05). There was a strong correlation between the increase in knee joint force and the increase in the moment arm of the ground reaction force. Images produced using the three-dimensional Vicon system confirm that toe sliding produces a larger moment arm than flatfoot sliding. CONCLUSION: Injuries are more likely to occur in toe sliding, compared with flatfoot sliding, due to the increase in force and moment, pushing the weight of the curler forward over the knee, which could make the adopted position less stable. Curlers might consider avoiding toe sliding to reduce the risk of knee injuries if the two types of delivery could be performed equally well.