The trade-off between distance and accuracy in the rugby union place kick: a cross-sectional, descriptive study

Little attention has been given to the rotational kinematics of the rugby union place kicking performance, especially in a field setting. The place kick is a means to score points. By maximizing the distance and accuracy a kicker is able to achieve increases the number of point scoring opportunities available to a team. The hypothesis of this study was that there is a relationship between distance and accuracy and the rotational kinematics of place kicking performance of rugby players in the field setting. Twelve first-team university rugby players had their full body kinematics measured for five place kicks. Kick distance and accuracy were directly measured. The current study showed a positive correlation between torso (r=.76) and pelvis (r=.66) rotation with kick distance. Place kick distance (r=.24) or accuracy (r=.54) were not correlated to playing experience. Negative correlations between stance elbow flexion (r=-.78), torso rotation (r=-.74) and X-factor (r=-.79) with kick accuracy were noted. Place kick distance could potentially be maximized by improving torso and pelvic rotations. Place kick accuracy could be improved by full extension of the stance arm. The data suggests that larger torso rotations may promote kicking distance; however, they impede kicking accuracy

Objective measurements and characteristics of spinal excitability in restless Legs syndrome patients

Original published work submitted to the Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, in fulfilment of the requirements for the degree of Doctor of Philosophy. Johannesburg, South Africa, 2018.Restless legs syndrome (RLS) is a neurological disorder that presents with sensory and motor symptoms that worsen in the evening and with rest. An evening state of spinal hyperexcitability has been proposed to be a possible cause of evening increases in RLS symptoms. Therefore the studies included in this thesis aimed to assess circadian variations in the state of spinal excitability in RLS patients in order to extend our knowledge about alterations in spinal processing and provide further elucidation of the pathophysiological mechanisms involved in RLS. The first two studies of this thesis assessed circadian variations in spinal excitability in terms of spinal reflex responses of RLS patients compared to control participants. The plantar, flexor withdrawal, and crossed extensor reflexes all showed a circadian rhythm in RLS patients suggesting an evening increase in spinal excitability. We theorise that the circadian variation in spinal excitability in RLS patients may be due to an evening form of central sensitization particularly affecting nociceptive responses. These results reinforce the notion that there is increased spinal cord excitability in the evening in RLS patients, which corresponds to the symptomatic period of RLS. Although RLS patients demonstrated a circadian variation in the reflex responses, indicating a possible increase in spinal excitability in RLS patients in the evening, RLS patients showed no increases in spinal excitability when compared to control participants. An unexpected finding was decreased plantar reflex responses in RLS patients compared to control participants. Excitability of both the flexor withdrawal and crossed extensor reflexes demonstrated no significant differences between RLS patients and control participants. These results do not support the theory of increased spinal excitability in RLS patients. The findings indicate that the pathophysiology of RLS is likely to involve complex spinal alterations. The concept of global spinal hyperexcitability in RLS patients does not take into account the complex interactions of various sensory modalities in the spinal cord. The plantar, flexor withdrawal, and crossed extensor reflexes studies in this thesis investigated spinal excitability in RLS patients in a static environment. However, dynamic sensorimotor integration is likely to play a role in RLS as inactivity brings on RLS symptoms and movement relieves RLS symptoms. Therefore, the third study of this thesis investigated temporal changes during locomotion in RLS patients using electromyography (EMG) of the muscles involved in gait in order to evaluate dynamic sensorimotor feedback in RLS patients. EMG muscle activity during the gait cycle did not show the circadian variation in RLS patients that was seen in healthy control participants. However, evening differences in gait muscle activation patterns between RLS patients and control participants were evident. These results extend our knowledge about alterations in spinal processing during gait in RLS patients. A possible explanation for these findings is central pattern generator sensitization caused by alterations in sensitivity of cutaneous afferents in RLS patients. In conclusion, the results of these studies provide further insight into the pathophysiology of RLS, highlighting that RLS is not due to a global state of spinal hyperexcitability. As not all sensory processing is affected in the same manner the pathophysiology of RLS is likely to involve complex spinal alterations.LG201

An assessment of the clinical application and utility of the Babinski sign using objective kinematic and electromyographic methods

Dissertation submitted to the Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, in fulfilment of the requirements for the degree Master of Science. 2013The Babinski sign is a pathological response elicited by a stimulus to the lateral plantar border of thesole of the foot. The resulting reflex involves dorsiflexion (upward motion) of the toes, most notably the hallux, with accompanying flexion in the ankle, knee and hip. It is an important part of the clinical neurological examination and aids in the diagnosis of central nervous system dysfunction. There is however no wholly standardised method to elicit this reflex or interpret it, resulting in possible variation in its utility. The resulting aim of the studies constituting this dissertation were therefore to: 1) assess what techniques and pressures are used to elicit the reflex in a group of neurologists;2) to investigate the relationship between input variables of the reflex and the resultant output variables as measured with the use of electromyography and kinematics;3) compare objective variables, relating to toe, foot and leg movement, of the pathological reflex to the healthy response; 4) assess the inter-rater reliability of the reflex and 5) determine what aspects of the reflex are most closely related to the ratings of the students and neurologists. A specialized custom-built Babinski hammer was constructed to measure the duration of the stroke and pressures exerted on the foot of a single healthy subject by neurologists (n=12). The relationship between the recorded pressures and the movement of the toes (measured kinematically), muscle activity in the tibialis anterior and the pain felt by the subject (gauged using a visual analogue scale) were evaluated. Following this, the average pressure used by the neurologists was used to elicit the reflex in six patients with known positive Babinski responses and six healthy gender and age matched controls. These reflexes were compared with kinematic (measurement of toe, foot and leg movement) and electromyographic (muscle activity of the involved muscles) methods. These reflexes were recorded and the recorded footage was shown to 12 medical students and 12 neurologists who were asked to interpret if 3 the responses were pathological or non-pathological. Kinematic and electromyographic descriptions of each reflex made it possible to assess what aspects of the reflex are important for classification of a pathological response for both medical students and neurologists. A large amount of intra- and inter-rater variability was shown amongst the neurologists in how they elicited the reflex. The amount of pressure applied was shown to be significantly related to hallux movement (p<0.01) as well as to the degree of pain felt by the subject (p<0.01). Significant differences were found between the patients and controls for change in hallux angle (p<0.0001), movement latency (p<0.05)and the maximum electromyographic amplitude of tibialis anterior(p<0.01). The inter-rater reliability of the medical students and the neurologists showed substantial agreement between raters (kappa = 0.67 and 0.72 respectively). Both neurologists and students made use of the change in hallux angle, time taken to reach maximum ankle angle, movement latency and the maximum amplitude of gastrocnemius when rating the reflex. Neurologists alone observed time taken to reach maximum hallux angle and change in ankle angle as being important while medical students‘ alone looked at maximum amplitude of biceps femoris. In conclusion, I found a large variation between the techniques of neurologists when assessing the Babinski reflex. This variation is related to variation in aspects of the resultant reflex. The pathological response (the Babinski sign) has shorter movement latency and less activity in the tibialis anterior muscle than the flexor response seen in healthy individuals. Ratings of pre-recorded Babinski responses had substantial agreement when both neurologists and medical students assessed pathology. In order to assess them both groups made use of the speed of the reflex, the direction of hallux movement and concurrent withdrawal activity in the leg to differentiate between a pathological and a healthy response

Relationships between physical and biomechanical parameters and golf drive performance: a field-based study

A proficient golf swing is composed of a sequence of highly complex biomechanical movements and requires precisely timed and coordinated body movements to achieve great distance and accuracy. The aim of the current study was to identify the key physiological and biomechanical variables that relate to golf drive performance. Eighteen golfers (handicap 11±6 strokes, playing experience 18±15 years), volunteered to take part in the study. Drive distance and accuracy were measured directly. Balance was assessed using a modified stork test and hand-eye coordination was assessed using a 3D maze. Average balance duration of both legs (r= 0.563; p=0.015), left leg (r= 0.620; p=0.006) and right leg (r= 0.488; p=0.044) were all significantly correlated to drive distance. Hand-eye coordination was significantly negatively correlated to total drive distance (r=-0.600 p=0.008), but was not associated significantly with the centre of hit between the clubface and ball. Several parameters were found to have significant relationships to golf drive distance in a group of amateur golfers. Therefore, training regimes could include tasks that aim to improve hand-eye coordination and balance.Key words: Co-ordination; Balance; Biomechanics; Golf; Performance