Warrick McKinon

Anthropometric, biomechanical, and isokinetic strength predictors of ball release speed in high-performance cricket fast bowlers

Abstract Fast bowling is fundamental to all forms of cricket. The purpose of this study was to identify parameters that contribute to high ball release speeds in cricket fast bowlers. We assessed anthropometric dimensions, concentric and eccentric isokinetic strength of selected knee and shoulder muscle groups, and specific aspects of technique from a single delivery in 28 high-performance fast bowlers (age 22.0 ± 3.0 years, ball release speed 34.0 ± 1.3 m · s−1). Six 50-Hz cameras and the Ariel Performance Analysis System software were used to analyse the fast and accurate deliveries. Using Pearsons correlation, parameters that showed significant associations with ball release speed were identified. The findings suggest that greater front leg knee extension at ball release (r = 0.52), shoulder alignment in the transverse plane rotated further away from the batsman at front foot strike (r = 0.47), greater ankle height during the delivery stride (r = 0.44), and greater shoulder extension strength (r = 0.39) contribute significantly to higher ball release speeds. Predictor variables failed to allow their incorporation into a multivariate model, which is known to exist in less accomplished bowlers, suggesting that factors that determine ball release speed found in other groups may not apply to high-performance fast bowlers.

Static and dynamic balance ability, lumbo-pelvic movement control and injury incidence in cricket pace bowlers.

OBJECTIVES This study aimed to establish the difference in lumbo-pelvic movement control, static and dynamic balance at the start and at the end of a cricket season in pace bowlers who sustained an injury during the season and those who did not. DESIGN This is a longitudinal, observational study. METHODS Thirty-two, healthy, injury free, male premier league fast, fast-medium and medium pace bowlers between the ages of 18 and 26 years (mean age 21.8 years, standard deviation 1.8 years) participated in the study. The main outcome measures were injury incidence, lumbo-pelvic movement control, static and dynamic balance ability. RESULTS Fifty-three percent of the bowlers (n=17) sustained injuries during the reviewed cricket season. Lumbo-pelvic movement control tests could not discriminate between bowlers who sustained an injury during the cricket season and bowlers who did not. However, performance in the single leg balance test (p=0.03; confidence interval 4.74-29.24) and the star excursion balance test (p=0.02; confidence interval 1.28-11.93) as measured at the start of the season was better in bowlers who did not sustain an injury during the season. CONCLUSIONS The improvement in the lumbo-pelvic movement control and balance tests suggests that the intensity and type of physical conditioning that happens throughout the season may have been responsible for this improvement. Poor performance in the single leg balance test and the star excursion balance test at the start of the cricket season may be an indication that a bowler is at heightened risk of injury.

The accuracy of subjective clinical assessments of the patellar reflex.

Introduction: Measurement precision and accuracy of spinal reflexes plays an essential role in the clinical neurological examination. Reflexes are conventionally assessed either electromyographically or with rating scales. In this study we compared objective kinematic T‐reflex and subjective assessments of patellar reflexes in 15 normal healthy subjects. Methods: Randomized recordings of objectively quantified reflexes were rated by 24 medical students, 16 general practitioners, and 12 neurologists, using a visual analog scale and the NINDS and Mayo clinical reflex scales. Results: For all groups of raters, Spearman rank correlations showed that subjective ratings significantly correlated with change of knee angle (R2 = 0.72–0.79, P < 0.001) and maximum T‐reflex amplitude (R2 = 0.84–0.94, P < 0.001). Stepwise multiple regression analysis showed that all subjective rater groups relied most on the change of knee angle to assess the reflex. Conclusions: These findings show that subjective assessments of reflexes using reflex rating scales correlate strongly with biomechanical and electromyographic measures. Muscle Nerve, 2013

Injury and lumbar reposition sense in cricket pace bowlers in neutral and pace bowling specific body positions

BACKGROUND AND CONTEXT The cricket pace bowling action consists of a complex sequence of forceful actions, involving practiced, particular movements of the lumbar spine. The nature and repetition of the pace bowling action is known to be associated with a high incidence of low back injuries. PURPOSE This study aimed to establish whether lumbar proprioception (as measured by joint position sense) in the neutral lumbar spine position as well as lumbar positions corresponding to those at front foot placement and ball release positions of the cricket pace bowling action were related to previous injury and injury sustained during the cricket season under review. Injuries specifically sustained during the bowling action and those specific to the low back were explicitly investigated. STUDY SETTING Longitudinal study with participants tested at the start and monitored over the duration of a cricket season. PARTICIPANT SAMPLE Seventeen male cricket pace bowlers between the ages of 18 and 26 years participated in this study. OUTCOME MEASURES Physiological outcome measures were used. Lumbar position sense was established using electrogoniometry. METHODS Lumbar reposition error was measured in three positions (neutral lumbar spine, front foot placement, and ball release bowling positions). In each position, lumbar orientation was determined in the sagittal (flexion-extension) and coronal (left-right lateral flexion) planes. Wilcoxon matched-pairs ranks and Kruskal-Wallis tests were used to establish the relationship between variables. RESULTS Reposition error was associated with general injuries sustained in the past and during the cricket season under review, low back injuries, as well as injuries sustained during the bowling action (p<.05). CONCLUSION Lumbar position sense, as a measure of proprioception, was related to injury in general, injuries sustained during the bowling action, and, especially, low back injury sustained in the past. Low back injury prevention methods are particularly needed because of the high load nature of the pace bowling action. If the proprioception of the lumbar spine is improved in pace bowlers, their risk of lumbar injury can potentially be reduced.

The agreement between reaction-board measurements and kinematic estimation of adult male human whole body centre of mass location during running

The segmental method for estimating the centre of mass (COM) location of the human body has been widely used since 1889. How closely this method agrees with direct measurements of the location and movement of COM during activity however, remains unclear. To test this, a novel reaction-board utilizing life sized projections of human subjects is designed for measuring COM location. Agreement between the segmental method and the more direct reaction-board measurement method is then assessed. Our data demonstrate that the reaction-board system has a physical maximum error of 1.28 cm and 1.95 cm for locating COM along the vertical (board length) and horizontal (board width) axes respectively, and show that the reaction-board and segmental methods agree to within limits of 6.0 cm for the location of COM and to within 5.6 cm for the movement of COM between two points, in recumbent individuals. Applied to running, the segmental method agrees to within limits of 4.8 cm for oscillation of COM and 5.3 cm for stride median COM height. The segmental method agrees with a more direct technique of known accuracy, the reaction-board method, most closely when measuring averaged oscillation over repeated strides, where it displays a measurement error range of 5.1 cm to 0.1 cm in runners.

Kinematic and kinetic analysis of the inter- and intra-applicator assessment of the Babinski reflex

AIMS OF THE STUDY The first aim was to quantify variability in the mechanical technique used by neurologists to elicit the Babinski reflex. The second aim of the study was to assess if the mechanical technique is an important determinant of the subsequent reflex response. MATERIALS AND METHODS In this study, twelve neurologists elicited the Babinski reflex five times on the same foot of the same participant using a special reflex hammer which recorded the force and duration of the stroke. Hallux movement, tibialis anterior maximum EMG amplitude and pain felt by the participant for each stroke were recorded. RESULTS A large inter- and intra-applicator variability was shown amongst the neurologists. The change in hallux angle was significantly correlated with the duration of the stroke (R(2)=0.18, P<0.01), maximum (R(2)=0.14, P=0.01) and average (R(2)=0.17, P<0.01) force used to elicit the reflex. No correlations were shown between the hammer forces and duration and the maximum amplitude of the tibialis anterior. Significant correlations were shown between the pain score and the maximum (R(2)=0.15, P<0.01) and average (R(2)=0.17, P=0.001) force used to elicit the Babinski reflex. CONCLUSION These results indicate that there was substantial variation when performing the Babinski reflex test within and between neurologists which could lead to differences in the resultant reflex and therefore may affect subsequent diagnoses.

Side-to-side asymmetry in absolute and relative muscle thickness of the lateral abdominal wall in cricket pace bowlers

Background. The abdominal musculature plays a protective role against lower-back injury. Knowledge of the asymmetry in abdominal wall thickness in healthy, injury-free cricket pace bowlers may provide a useful platform against which pathology could be assessed and the effects of training could be evaluated. Objective. To compare side-to-side differences in absolute muscle thickness and activity of the abdominal musculature and to compare these measurements at the start, with those at the end of a cricket season among a group of amateur pace bowlers. Methods. This was a controlled longitudinal prospective study. Rehabilitative ultrasound imaging was used to assess abdominal muscle thickness in 26 right-handed, injury-free cricket pace bowlers at the start and at the end of a cricket season. Thickness measurements were done at rest, during an abdominal drawing-in manoeuvre (ADIM) and the active straight-leg raise (ASLR) on the left (-L) and right (-R). Results. The absolute thickness of the non-dominant obliquus abdominis internus (OI) was higher than that of the dominant OI at the start (p=0.001; ES=0.87) as well as at the end of the cricket season (p=0.001; ES 1.09). At the start of the season, the percentage change during the ADIM, thus muscle activity, was higher for the non-dominant OI than for the dominant OI (p=0.02; ES=0.51). Absolute thickness of the dominant obliquus abdominis externus (OE) at rest was significantly higher at the end of the season compared with the start of the season (p=0.0001; ES=0.85). During ASLR-R, the activity of the left transversus abdominis (TA) was significantly higher than that of the right TA during ASLR-L (p=0.03) when measured at the end of the season. Conclusion. This study highlights the possible muscle adaptations in absolute muscle thickness and activity as a consequence of the asymmetrical bowling action.

The patellar reflex: does activity of quadriceps femoris muscles reflect leg movement?

Abstract Objectives: The assessment of spinal reflexes has traditionally been performed by clinicians with minimal need for recording equipment, where doctors rely on their training and may use established subjective reflex rating scales. With advances in technology, it is now possible to assess reflexes objectively. This study compared two objective methods of assessing patellar reflex magnitude, duration, and latency, namely electromyography (EMG) of the quadriceps muscles and kinematic assessment of the leg movement around the knee joint. Methods: Reflexes of 24 healthy participants were assessed and seven variables were found to describe each reflex. These were the change in knee angle, the velocity of the reflex, the time to maximum knee angle, the biomechanical movement latency, the EMG maximum amplitude, the negative peak duration, and the EMG latency. Spearman’s rank correlation tests were run in order to compare all of the variables. Results: The results showed that there were positive correlations between EMG maximum amplitude and the change in knee angle (R2 = 0·75; P<0·0001) as well as the EMG maximum amplitude and the velocity of the reflex (R2 = 0·30; P = 0·0058). There was also a negative correlation between EMG maximum amplitude and the biomechanical movement latency (R2 = 0·35; P = 0·0024). Discussion: The results show that there is a relationship between muscle activity and the actual visual movement of the leg assessed using kinematics. This relationship is closest between kinematic measurements and EMG measures of reflex amplitude.

Extrinsic and intrinsic factors associated with non-contact injury in adult pace bowlers: a systematic review protocol

Review question/objective Review question: which extrinsic and intrinsic factors are associated with non‐contact injury in adult cricket pace bowlers? Review objective: the objective of this review is to determine the extrinsic and intrinsic factors associated with non‐contact injury in adult pace bowlers. Background Cricket is generally considered to be a sport of low injury risk1 compared to other sports.2 In cricket, the pace bowler strives towards the adoption of a bowling technique with a relatively low injury threat that will, at the same time, allow for a fast (>120km/hr) and accurate delivery to the opposing batsman. However, of all the various roles of the cricket player, the pace bowler has the highest risk of injury, especially for low back and lower limb (lower quarter) injury.3,4 The reason for this high risk of injury is due to the inherent, high‐load biomechanical nature of the pace bowling action.3‐5 The high prevalence of injury amongst pace bowlers3,4 highlights the great need for research into factors associated with injury. Both extrinsic and intrinsic factors work in combination to predispose the bowler to injury. Extrinsic or environment‐related factors include bowling workload (the numbers of overs a bowler bowls), player position (first, second or third change) and time of play (morning or afternoon). A high bowling workload has been linked with a higher risk of injury in pace bowlers. Foster et al.5 found in an observational study that bowling too many overs in a single spell or bowling too many spells may increase the pace bowlers risk of sustaining a low back injury. In another observational study, Dennis et al.6 found that an exceptionally high bowling workload as well as an uncommonly low bowling workload is associated with injury risk. The major extrinsic factors for bowling injury identified by Orchard et al.1 are a high number of match overs bowled in the previous week, number of days of play and bowling second (batting first) in a match. Extrinsic factors are known to make the bowler more susceptible to injury, especially in the presence of intrinsic factors. Intrinsic, or person‐related, factors include muscle strength, flexibility, balance and biomechanics.7‐11 Intrinsic, strength‐related factors, such as shoulder depression, horizontal flexion strength for the preferred limb and quadriceps power in the non‐preferred limb are also significantly related to back injuries in fast bowlers.5 Both upper limb and lower limb‐related intrinsic factors are known to be associated with injury. A prospective study by Dennis et al.12 aimed to identify the risk factors for injury in adolescent cricket fast bowlers. Their findings concluded that bowlers with a hip internal rotation range of motion of ≤30° on the leg ipsilateral to the bowling arm were at a significantly reduced risk of injury compared with bowlers with >40° of rotation. Moreover, bowlers with ankle dorsiflexion lunge of 12.1‐14.0 cm on the leg contralateral to the bowling arm were at a significantly increased risk of injury compared to bowlers with a lunge of >14 cm. Reduced hamstring flexibility was also associated with lumbar disc abnormalities.13 Bowling‐related biomechanical risk factors for injury have been established such as trunk rotation of the shoulders by to a more side‐on position during the delivery stride.5 Portus et al.14 also reported that shoulder counter‐rotation was significantly higher in bowlers who reported lumbar spine stress fractures, while the non‐trunk injured group displayed a more flexed knee at front foot contact and ball release. In addition to the above kinematic risk factors, there are high ground reaction forces associated with the power phase ‐ between the front foot placement and ball release components of the pace bowling action.15‐17 A combination of kinematic bowling related issues as described above and high ground reaction forces may predispose the bowler to injury. Morton et al.18 conducted a systematic review on pace bowlers between the ages of 13.7 and 22.5 years on risk factors and successful interventions for cricket‐related low back pain. Young cricketers between the ages of 13 and 18 years are different to adults in terms of their physiology which impacts on their predisposition to injury and phases of healing.19,20 Young cricketers may differ from an adult population in that young pace bowlers who sustain injuries during their bowling career may have given up on the sport by the time they approach adulthood, and the composition of the adult pace bowler population group is therefore affected by natural selection which may cause this group to differ from the original population. Caution is thus advised when generalizing findings from this young population group to adult pace bowlers which emphasizes the need for studies amongst adult pace bowlers. Furthermore, the review by Morton et al.18 included articles that specifically investigated factors associated with low back pain. However, due to the interconnectedness between the spine and the lower limbs, kinematic variables affecting the spine will also affect the load placed on the lower limbs21,22 with subsequent risk of injury.23 The interdependent mechanical interactions in a linked segment system such as the system of motion of the low back can be caused by movement coordination patterns in other body segments.24 The systematic review by Morton et al.18 only included intrinsic factors while the proposed review will also look at extrinsic factors. Therefore, the primary objective of this review is to determine extrinsic and intrinsic factors associated with non‐contact injury in adult pace bowlers.

Combined individual scrummaging kinetics and muscular power predict competitive team scrum success

Abstract Scrummaging is a major component of Rugby Union gameplay. Successful scrummaging is dependent on the coordination of the forward players and the strength of the eight individuals. The study aim was to determine whether individual scrummaging kinetics and other candidate factors associated with scrummaging performance discriminate team scrum performances. Sixteen club-level forwards (stature: 1.80 ± 0.1 m; mass: 99.0 ± 18.2 kg) were initially divided into two scrummaging packs. A total of 10 various scrum permutations were tested, where players were randomly swapped between the two packs. Winning scrums were determined by two observers on opposite sides of the scrum. Fatigue (100 mm visual analogue scale (VAS)) and scrummaging effort (6–20 rating of perceived exertion (RPE)) were assessed following each scrum contest. Individual scrummaging kinetics were acquired through an instrumented scrum ergometer and muscular power indicated through vertical jump heights. Student’s t-tests were used to differentiate between winning and losing scrum packs. VAS and RPE were assessed using repeated measures ANOVAs. Winning scrum packs had significantly larger combined force magnitudes (p < .002), regardless of the player contribution calculations. Additionally, winning packs had less individual movement (p = .033) and higher combined vertical jump heights (p < .001) but were not significantly heavier (p = .759) than losing scrum packs. While perceived VAS and RPE values progressively increased (p < .001), no differences in the individual scrum magnitudes were observed between the 1st and 10th scrum (p = .418). The results indicated that the combination of individual forces, variation in movement and factors related to scrummaging performance, such as vertical jump height, were associated with team scrummaging success.