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Biomedical subjects

R J Neal

Publications and source records attributed to R J Neal.

At least 19 recordsLinked to original sources
PubMed2002

A comparison of peak power in the shoulder press and shoulder throw.

The ability to generate peak power is central for performance in many sports. Currently two distinct resistance training methods are used to develop peak power, the heavy weight/slow velocity and light weight/fast velocity regimes. When using the light weight/fast velocity power training method it was proposed that peak power would be greater in a shoulder throw exercise compared with a normal shoulder press. Nine males performed three lifts in the shoulder press and shoulder throw at 30% and 40% of their one repetition maximum (1RM). These lifts were performed identically, except for the release of the bar in the throw condition. A potentiometer attached to the bar measured displacement and duration of the lifts. The time of bar release in the shoulder throw was determined with a pressure switch. ANOVA was used to examine statistically significant differences where the level of acceptance was set at p < 0.05. Peak power was found to be significantly greater in the shoulder throw at 30% of 1 RM condition [F, (1, 23) = 2.325 p < 0.051 and at 40% of 1 RM [F, (1, 23) = 2.905 p < 0.05] compared to values recorded for the respective shoulder presses. Peak power was also greater in the 30% of 1 RM shoulder throw (510 +/- 103W) than in the 40% of 1 RM shoulder press (471 +/- 96W). Peak power was produced significantly later in the shoulder throw versus the shoulder press. This differing power reflected a greater bar velocity of the shoulder throw at both assigned weights compared with the shoulder press.

Adult↗
PubMed1999

Visual characteristics of clay target shooters.

A comprehensive battery of standardised visual tests was administered to 11 skilled and 12 novice clay target shooters in an attempt to determine the distinctive visual characteristics of expert performers in this sport. The static and dynamic visual acuity, ocular muscle balance, ocular dominance, depth perception and colour vision of each of the subjects was measured in addition to their performance on simple and choice reaction time, peripheral response time, rapid tachistoscopic detection, coincidence timing and eye movement skills tasks. Expert superiority was observed on the simple reaction time measure only, and the novices actually outperformed the skilled subjects on a number of the other visual measures (viz., static acuity at near distance, dynamic acuity, vertical ocular muscle balance, choice reaction time and rapid target detection discriminability). Scores on all measures for both groups were within the expected normal range indicating that normal and not necessarily above-average basic visual functioning is sufficient to support skilled clay target shooting. An important implication of the finding that skilled shooters are not characterised by supranormal levels of basic visual functioning is the recognition that any attempt to improve shooting performance through training of general attributes of vision to supranormal levels is likely to be unproductive.

Adolescent↗
PubMed1999

Knee joint kinematics during the sidestep cutting maneuver: potential for injury in women.

PURPOSE: There is a paucity of data describing female lower limb biomechanics during "high risk" movements linked to noncontact ACL injury. This study compared, across gender, knee kinematics associated with sidestepping maneuvers to provide insight into why women display a significantly higher incidence of this injury than do men. METHODS: Thirty participants (16 men, 14 women) had bilateral knee joint kinematic data recorded while sidestepping. A custom software package (JTMOTION) quantified maximum, minimum, and range of motion during stance for each of the three clinical knee joint rotations (flexion/extension, adduction/abduction and external/internal rotation) over 20 (leg x condition x trial (5)) trials. RESULTS: Gender differences possessed limited clinical significance with all maximum values well within safe ranges of knee motion. Women did, however, display increased intertrial variability for axial rotation patterns during cutting compared with men. This variability was thought to be unaffected by gender, with experience level found statistically (P < 0.01) to be the major determinant of knee kinematic variability during sidestepping. Hence, the level of exposure to sidestep cutting may have a large impact on the subsequent risk of ACL injury when when one performs these maneuvers. CONCLUSIONS: Gender differences in knee motions during cutting did not contribute to the increased risk of noncontact ACL injury in women compared with men. The reasons for this increased incidence, therefore, remain unclear. The potential relationship between gender and other parameters linked to ACL injury such as joint geometry, ligament morphology, and physical conditioning requires further investigation.

Adult↗
PubMed1998

The dynamic loading response of surfaces encountered in beach running.

The purpose of this study was to measure the response to dynamic loading of sand surfaces typically encountered in beach running. An instrumented drop test rig was constructed and used to guide a drop mass through impact with two surfaces (i) dry, uncompacted sand; and (ii) wet, compacted sand. Four drop masses (3.86, 7.24, 10.62 and 14.0 kg) were chosen and dropped from four different drop heights (100, 200, 300 and 400 mm) to represent the kinetic energies typically experienced during heelstrike in running. Accelerations were measured using a piezoelectric accelerometer and the trajectory of the drop head was measured using a displacement transducer. The following response variable were calculated for each trial: (i) peak impact force, (ii) mean impact force, (iii) impulse, (iv) total impact time, (v) rise time, (vi) fall time, (vii) maximum penetration, (viii) energy absorbed by the surface, and (ix) surface stiffness. Mean and peak impact forces were approximately 4 times greater for the wet surface while penetration, impact time and rise time were approximately 3-4 times greater for the uncompacted surface condition. The wet surface was also found to be 6 times stiffer than the uncompacted surface indicating the presence of water substantially altered surface compliance. Results are discussed in terms of their implications for performance and the potential for injury to athletes who run on these surfaces.

Algorithms↗
PubMed1998

A quantitative analysis of knee joint kinematics during the sidestep cutting maneuver. Implications for non-contact anterior cruciate ligament injury.

This study accurately quantifies the knee joint kinematics associated with sidestep cutting maneuvers in vivo. These data were subsequently evaluated to determine the relationship between sidestep cutting and non-contact anterior cruciate ligament (ACL) injury. Sixteen male subjects, proficient in the sidestep cutting maneuver, had knee joint kinematic data recorded during the stance phase of straight line running and sidestep cutting. Cutting speeds (5.5 msec-1 to 7.0 msec-1) and angles (30 degrees to 55 degrees) were chosen to reflect the sporting context. All subjects underwent medical screening prior to testing to ensure data represented joint biomechanics of healthy, ACL intact individuals. The temporal three dimensional positions of externally mounted (skin) markers were submitted to a custom software package (JTMOTION), which described in clinically meaningful terms, movements for the three rotational degrees of freedom at the knee joint. While mean patterns of motion for the three clinical knee rotations compared favorably between running and cutting data, sidestepping induced significantly (p < 0.01) greater maximum knee joint rotations during stance. Knee joint rotational ranges were also found to be significantly (p < 0.01) larger during cutting when compared to running. Increases in knee joint kinematics during cutting however, were not of a great enough magnitude to alone elicit spontaneous non-contact ACL injury, falling well within "safe" ranges of knee motion. Significant increases in inter-trial variability for the three rotations were observed in some subjects for sidestepping compared to running. It was concluded that a lack of consistency in knee joint biomechanics between cutting maneuvers increased the risk of ACL injury with the performance of an abnormal and potentially hazardous sidestep being more likely. The risk of non-contact ACL injury during cutting maneuvers was suggested to increase further when an individual displayed these "atypical" joint biomechanics in conjunction with specific joint structures, levels of experience and conditioning, and ligament morphologies.

Adult↗
PubMed1996

An injury profile of elite ironman competitors.

An injury questionnaire was administered to the 30 elite ironman competitors (mean age = 25.7 +/- 4.6 yrs) participating in a commercially sponsored seven race national series. Responses provided retrospective data from the preceding three years indicating the type, location, frequency, cause and severity of injuries sustained by ironmen, and associated these injuries with particular race components (run, swim, board, ski). Twenty self-reported questionnaires were returned for analysis that described a total of 67 injuries incurred by 19 subjects. Results indicated the following: (i) the most frequently injured body parts were the knee (n = 18) and shoulder (n = 14) with the lower extremity accounting for 55% of all injuries reported; (ii) knee, shin and calf injuries had a significant association with the run component and upper extremity injuries had a significant association with the swim component; (iii) running was perceived to be the most injurious race component in terms of the frequency and severity of injury; (iv) overtraining was perceived to be the main cause of injury; (v) tendinitis was perceived to be the main type of injury; (vi) athletes adjusted their training mode to accommodate injury so that total training volume could be maintained; and (vii) injury did not result in withdrawal from competition. Further research investigating the techniques used in the ironman event and their relationship to injury is recommended.

Adult↗
PubMed1995

Self-selected manual lifting technique: functional consequences of the interjoint coordination.

The pattern of movement self-selected by 39 subjects to lift light loads from 9 cm above the ground is described in kinematic and electromyographic terms. Hamstring length changes were estimated from hip and knee angular kinematics. Subjects adopted a posture at the start of the lift intermediate between stoop and full-squat postures. A consistent coordination between knee, hip, and lumbar vertebral joints during lifting was described through calculation of the relative phase between adjacent joints and found to be exaggerated with increases in load mass. During the early phase of lifting, knee extension leads hip extension, which in turn leads extension of the lumbar vertebral joints. Early in the lifting movement, when load acceleration is greatest, the erectores spinae are thus relatively long and shortening slowly. Both of these factors produce greater back extensor strength. Rapid hamstring shortening is also delayed, which enhances their strength, and coactivation of the monoarticular knee extensors and biarticular hamstring observed early in the lifting movement suggested that the knee extensors contribute to hip extension through a tendinous action of the hamstrings.

Adult↗
PubMed1995

The influence of hand guards on forces and muscle activity during giant swings on the high bar.

To investigate the influence of hand guards on the loads experienced by gymnasts during giant swings on the high bar, forces applied to the bar by each hand and muscle activity of the extrinsic finger flexor and wrist extensor muscle groups were measured in 10 male gymnasts as they completed a minimum of three backward giant swings on the high bar. Measurements were made under four conditions of performance: bare hands, with webbing loops, with doweled hand guards (DHG), and a wind-up swing using DHG. Peak reaction forces at the hands were of the order of 2.2 times body weight (BW) on each hand, and were significantly (P < 0.05) lower when swinging bare-handed, compared with the other three conditions. By contrast, the integrated electromyograms showed that both wrist flexor and extensor muscle activity was unchanged across conditions. These results indicate that the use of hand guards allows greater tensile forces to act across the wrist without a measureable increase in forearm muscle activity. Thus, it is possible that there is extra stress on the ligaments of the wrist or at the epiphyseal plates. In adolescent and preadolescent gymnasts, the additional tension on the distal epiphyses of the radius and ulna may have implications for bone growth.

Adult↗
PubMed1993

Relative phase quantifies interjoint coordination.

This note illustrates by example how expression of joint movement on a phase plane can quantitatively describe multijoint coordination during complex actions. Automatic digitisation of high-speed video records was used to obtain lumbar vertebral, hip, knee and ankle joint angular kinematics in the sagittal plane of a subject performing a symmetric two-handed lifting movement. A consistent proximal-to-distal coordination was illustrated via angle-angle and relative phase angle presentations. During bending to pick up a load, the joints began their movement in the order proximal to distal while the reverse order of joint involvement occurred during extension. Phase angle relationships between joints may provide sufficiently sensitive measurements to identify changes in multijoint coordination induced by alterations in task variables such as (in the case of lifting) object mass, lifting height and load moment. Information regarding multijoint coordination is likely to be important in attempting to understand the respective roles and interaction between the bi and monarticular muscles which are involved in everyday complex actions like lifting.

Adult↗
PubMed1992

Against relative timing invariance in movement kinematics.

The kinematics of stair climbing were examined to test the assertion that relative timing is an invariant feature of human gait. Six male and four female subjects were video-recorded (at 60 Hz) while they climbed a flight of stairs 10 times at each of three speeds. Each gait cycle was divided into three segments by the maximum and minimum angular displacement of the left knee and left foot contact. Gentner's (1987) analysis methods were applied to the individual subject data to determine whether the duration of the segments remained a fixed proportion of gait cycle duration across changes in stair-climbing speed. A similar analysis was performed using knee velocity maxima to partition the gait cycle. Regardless of how the gait cycle was divided, relative timing was not found to remain strictly invariant across changes in speed. This conclusion is contrary to previous studies of relative timing that involved less conservative analysis but is consistent with the wider gait literature. Strict invariant relative timing may not be a fundamental feature of movement kinematics.

Adult↗
PubMed1991

Bidirectional promoter and terminator regions bracket mmr, a resistance gene embedded in the Streptomyces coelicolor A3(2) gene cluster encoding methylenomycin production.

Low- and high-resolution nuclease mapping of in vivo transcripts, and in vitro transcription reactions using purified RNA polymerase, were used to analyse transcription of and around the mmr gene, which specifies resistance of Streptomyces coelicolor A3(2) to methylenomycin (Mm) and is located in the middle of a cluster of Mm-production-encoding genes. Transcription of mmr is from a single major start point (tsp) which is separated by only 81 bp from a divergent tsp. A pattern of direct and inverted repeats in the nucleotide sequence in this region may play a part in regulation of these promoters. The 3' end of the mmr transcript overlaps by 20-30 bp the 3' end of an RNA molecule involved in Mm production. The converging transcripts both terminate at the same large inverted repeat in the DNA. Purified RNA polymerase terminated transcription at this sequence in vitro (albeit only in one orientation).

Anti-Bacterial Agents↗
PubMed1991

Note: A statistical problem in testing invariance of movement using the phase plane model.

Invariant positions on a phase plane of joint angular position and velocity have been proposed as a means by which interlimb coordination may be achieved. This note identifies a problem in the testing, using conventional statistics, of hypotheses derived using the phase plane model. A possible solution is proposed based on directional statistics. Conclusions regarding phase angle invariance, which are based on conventional statistics, must be viewed with some caution.

Journal Article↗
PubMed1988

The gait of pacers. 1: kinematics of the racing stride.

Standardbred pacers have been studied under race conditions to describe the gait of the pacer, and to determine relationships between stage of the race, finish order and selected gait kinematics. Overlap increased with the stage of the race while pacing speed decreased marginally for low order pacers and increased for high order finishers. High order finishing pacers appear to have greater stance and stride lengths than do low order finishers. Pacers could be separated into low order and high order groups on the basis of their movement patterns. High order pacers exhibited greater ranges of limb motion than did low order finishers.

Animals↗
PubMed1988

The gait of pacers. 2: factors influencing pacing speed.

Standardbred pacers were studied at four different nominated speeds and selected gait kinematics were analysed to determine factors which contribute to pacing speed. A deterministic model is proposed in which pacing speed is a function of stride length and stride timing variables. Stance length and suspension time remained relatively constant over the different pacing speeds. Variables which discriminated best between pacing speeds were suspension length and overlap time. At near maximal speed, the pacers increased speeds with increased stride length. This was attributed to an increased suspension length with little difference in suspension times. A 22 per cent increase in pacing speed resulted in a 13 per cent increase in stride length, 26 per cent increase in suspension distance, 8 per cent increase in stride frequency, 35 per cent and 16 per cent increases in advanced placement and completion times and a 23 per cent decrease in the period of overlap.

Animals↗
PubMed1987

Nucleotide sequence analysis reveals similarities between proteins determining methylenomycin A resistance in Streptomyces and tetracycline resistance in eubacteria.

Previous studies had localised the gene (mmr) for resistance to methylenomycin A (Mm) to a 2.5-kb PstI fragment in the middle of a cluster of Mm biosynthetic genes from the Streptomyces coelicolor plasmid SCP1. In this paper, the gene has been more precisely located by sub-cloning, and the nucleotide sequence of the whole fragment has been determined. The predicted mmr-specified protein (Mr 49238) would be hydrophobic, with some homology at the amino acid level to tetracycline-resistance proteins from both Gram-positive and Gram-negative bacteria. Comparisons of hydropathy plots of the amino acid sequences reinforces the idea that the proteins are similar. It is suggested that Mm resistance may be conferred by a membrane protein, perhaps controlling efflux of the antibiotic. No significant homology was detected by hybridisation analysis between mmr and a cloned oxytetracycline (OTc)-resistance gene (tetB) of the OTc producer Streptomyces rimosus, and no cross-resistance was conferred by these genes. Sequences on both sides of mmr appear to encode proteins. The direction of translation in each case would be opposite to that of mmr translation. This suggests that mmr is transcribed as a monocistronic mRNA from a bidirectional promoter. An extensive inverted repeat sequence between the stop codons of mmr and the converging gene may function as a bidirectional transcription terminator.

Amino Acid Sequence↗
PubMed1985

Scaling segmental moments of inertia for individual subjects.

The purpose of this investigation was to validate methods of scaling human segmental moments of inertia for the transverse principal axis. Firstly, two methods of scaling Chandler et al.'s (Pamphlets DOT HS-801 430 and AMRL TR-74-137, Wright Patterson Air Force Base, OH, 1975) mean subject data to estimate the segmental moments of inertia were used. Chandler et al.'s data were scaled using body mass and segment length (formula 1) or body mass and standing height (formula 2). These data were then compared with a procedure of using the cadaver whose anthropometric measurements most closely match those of the subject. The difference between the criterion data (Chandler's subject data) and scaled values were plotted on scatter diagrams with confidence limits of p less than 0.05 at d.f. = 17. For procedure 1, 43% of the scaled values were plotted within the confidence limits using formula (2) (mass and standing height), compared with 26% for formula (1) (mass and segment length). Formula (1) markedly underestimated the tallest and heaviest subjects. In procedure 2, only 16% and 21% of the scaled values, using formula (1) and (2), respectively, fell within the confidence limits. Results suggested that scaling formulae approximate the moment of inertia of body segments with only limited accuracy. However, if scaling was to be adopted then mean moment of inertia data from an appropriate data set, using the formula that incorporates subject mass and standing height, gave results closest to the criterion value.

Anthropometry↗