Thesis--University of Helsinki, 1988. / Also published in : Proceedings of the Finnish Dental Society, 1988, vol. 84, Suppl. VI. Includes bibliographical references.

This study investigates the effects of cumulative concussive and subconcussive mild head injury on the cognitive functioning of professional rugby players. A comprehensive battery of neuropsychological tests was administered to 26 professional rugby players and a noncontact sport control group of 21 professional cricket players. The test performances of the rugby players were compared to those of the cricket players. Within the rugby group, forward and backline players were compared. An analysis of mean score differences between the rugby and cricket group failed to support the presence of brain damage effects in the rugby group. However, there was significantly increased variability of scores for the rugby players compared with the cricket players on tests particularly sensitive to cognitive deficit associated with mild head injury. This invalidates the null indications of average effects, indicating that a notable proportion of rugby players’ performances were falling off relative to the rest of the rugby players on tests vulnerable to the cognitive effects of diffuse brain damage. Mean score comparisons within the rugby group indicated that it was the subgroup of forward players, in particular, whose test performances revealed deficits suggestive of cerebral damage. Specifically, deficits were found in working memory, visuoperceptual tracking, verbal memory and visual memory, a pattern of deficits commensurate with cumulative mild head injury. The theoretical perspectives of Satz’s (1997) Brain Reserve Capacity Theory and Jordan’s (1997) ‘Shuttle’ model of variability are drawn upon in order to elucidate research findings and suggestions for future research are provided.

This study investigates the effects of cumulative mild head injury on the cognitive functioning of elite rugby players. A comprehensive battery of neuropsychological tests was administered to top national (Springbok) rugby players (n=26), national Under 21 rugby players (n= 19), and a non-contact sport control group of national hockey players (n=21). The test results of the Total Rugby group (Springbok Rugby and Under 21 Rugby players), the Under 21 Rugby group, the hockey controls, and the Total Rugby and Under 21 Rugby forward and backline players respectively, were each compared with established normative data. Results showed significant differences in the direction of a poorer performance relative to the norms for the Total Rugby and Under 21 Rugby groups, and for the Total Rugby Forwards and Under 21 Rugby Forwards, on tests sensitive to the effects of diffuse brain damage. On the other hand, the Hockey Control group and the Total Rugby Backs and Under 21 Rugby Backs tended to perform within the normal range or better than the norm on some tests. These results confirm the hypothesis that rugby players, and the forward players in particular, are at risk of adverse cognitive effects consequent on cumulative mild head injury. The theoretical implications are that the aggregate effects of multiple exposures to mild head injuries in the rugby players served to reduce their brain reserve capacities and acted as a threshold-lowering influence associated with symptom onset.

sustained multiple concussions may be at risk of cumulative impairment. The role of neuropsychological testing in the management of sports-related concussion is a contentious and challenging issue which has gained credibility given the lack of clear and well-established guidelines pertaining to the diagnosis, assessment and return-to-play decisions following concussion. Despite various traditional paper and pencil tests being shown to be effective indicators of postconcussive neuropsychological dysfunction, testing has not been widely implemented, due to time- and labour-demands. ImPACT, a computer-based neuropsychological assessment instrument, has been recognised as a valid and reliable tool in the monitoring of athletes' symptoms and neurocognitive functioning preseason and postconcussion. As a part of larger-scale concussion research conducted on top-team university rugby players, this is an in-depth case study conducted on a 20-year old participant with a history of multiple concussions, who was referred following a concussion sustained during the season. The objectives of the study were: (i) to determine the sensitivity of ImPACT versus WAIS-III Digit Span and Trail Making Test during the acute postconcussive phase; and (ii) to examine the sensitivity of ImPACT versus a comprehensive battery of neuropsychological tests to possible residual deficits as a result of the multiple concussions. ImPACT was determined to be more sensitive to acute postconcussive impairment following concussion than Digit Span and Trail Making Test. Furthermore, the ImPACT preseason baseline scores appear to be sensitive to neurocognitive dysfunction, possibly due to cumulative concussive injuries.

This study investigates the cumulative effects of concussive and subconcussive mild head injury on the cognitive functioning of schoolboy rugby players. A comprehensive battery of neuropsychological tests and a self-report postconcussive questionnaire were administered to top level schoolboy rugby players (n=47), and a non-contact sport control group of top level schoolboy hockey players (n=34). Group comparisons of the percentage of individuals with cognitive deficit were carried out between i) the schoolboy rugby and the schoolboy hockey players, ii) the rugby forward and the rugby backline players; iii) the rugby forward and the schoolboy hockey players and, iv) the rugby backline and the schoolboy hockey players. Results on the neuropsychological test battery did not provide any substantial evidence of a higher level of neuropsychological impairment in the rugby players relative to the control group, or in the rugby forward players relative to the rugby backline players. Results obtained on the postconcussive symptom questionnaire provided tentative indications that the rugby players do report a greater frequency of postconcussive symptomatology. The symptoms most frequently reported were being easily angered, memory problems, clumsy speech and sleep difficulties. It was hypothesized that the absence of cognitive impairment in the schoolboy rugby players compared with that noted for professional players was due to their younger age, relatively high IQ and education level and a less intensive level of physical participation in the sport, and hence less accumulated exposure to the game, thereby decreasing their exposure to mild head injuries. From a theoretical perspective, these pre-existing conditions were considered to act as protective factors against reductions in brain reserve capacity and concomitant susceptibility to the onset of neuropsychological dysfunction.

The study sought to determine whether there is evidence for the presence of residual (chronic) deleterious effects on cognition due to repetitive mild traumatic brain injury in top team university level rugby players, using ImPACT 3.0, Trail Making Test (TMT) and Digit Span. The initial sample of 48 participants was divided into groups; Rugby (n = 30) and Controls (n = 18), Rugby Forwards (n = 14) and Rugby Backs (n = 16). A reduced sample (N = 31) comprised of Rugby (n = 20) and Controls (n = 11), Rugby Forwards (n = 9) and Rugby Backs (n = 11). Comparative subgroups were equivalent for estimated IQ but not for age and educational level in the full sample; in the reduced sample there was equivalence for all three variables of age, education and estimated IQ. All cognitive test measures were subjected to independent t-test analyses between groups at the pre- and post-season, and dependent t-test analyses for Rugby and Controls at pre- versus post-season. Overall, the results implicated the presence of deleterious effects of concussive events on Rugby players in the areas of speed of information processing, working memory and impulse control. Significant practice effects were found on the TMT and Digit Span for controls, but not on ImPACT 3.0, supporting the use of this computer-based programme in the sports management context.

This study investigated the cumulative effect of mild head injuries on rugby players. A comprehensive battery of neuropsychological tests was administered and subjects completed a self-report postconcussive symptom questionnaire. Data were collected for the two rugby groups, Springbok rugby players (n = 26) and Under 21 rugby players (n = 19), and for the control group, national hockey players (n = 21). Group comparisons of the percentage of individuals with deficit or self-reported symptomatology were made between: (i) the contact sport groups and the control group; (ii) the forwards and the backs within each rugby group and the rugby forwards and the control group; and (iii) the Springbok and Under 21 rugby players. Broadly speaking, comparative results on the neuropsychological tests and the self-reported postconcussive symptoms clearly distinguished between contact sport players and non-contact sport players and indicated the presence of diffuse brain damage in the contact sport players. There was also clear evidence of positional variation within the rugby groups, with the forwards (more full contact positions) most susceptible to impairment. Neuropsychological test results revealed deficit in information processing speed, attention and concentration, mental flexibility, visual memory and verbal new learning. The most significant neuropsychiatric complaints were reported in the areas of memory, social contact, sensitivity to noise, lowered frustration tolerance, anxiety and worry, and depression. The most sensitive neuropsychological test used in the present study was the Digit Symbol Substitution test. This test clearly distinguished contact sport players from non-contact sport players, and forwards from backs.

The objective of the study was to investigate the cumulative neurocognitive effects of repetitive concussive and subconcussive events in club level Rugby Union (hereafter rugby) during the course of one rugby season, in a combined group and individualized case-based approach. Amateur adult club level rugby players (n = 20) were compared with a non-contact control group (n = 22) of equivalent age, years of education and estimated IQ (p = > .05, in all instances), although the two groups were clearly differentiated on the basis of a history of reported concussions (p = < .05). Video analyses documented the tackling maneuvers observed amongst the players during all matches across the rugby season revealing a sobering average of more than a thousand tackles per player, excluding any contact practice sessions. Five rugby players (n = 5) who were observed to have a head jarring event were also isolated for individualized postconcussive follow-up analysis of their neurocognitive profiles. Measures included the ImPACT Verbal and Visual Memory, Visual Motor Speed and Reaction Time composites and the Purdue Pegboard. Independent and dependent statistical analyses were employed to compare the rugby versus control group neurocognitive test profiles at and between the three test intervals. Correlational analyses explored the association between concussion, tackling and neurocognitive test outcomes. Descriptive comparisons of individual neurocognitive test scores with normative data were employed for the case analyses. Taken together, the results implicated vulnerability amongst club rugby players on the motor and speeded tasks, with less robust indications on the memory tasks. While limited in terms of its small sample size, it is considered that the outcome of the study was rendered more robust by virtue of being methodologically multifaceted with heuristic implications for future research studies in the area. The novel inclusion of tackling data as well as fine-tuned case analyses, were of particular relevance in that regard. The results add to a growing body of literature that implicates deleterious neurocognitive effects in participants of a sport such as rugby due to repetitive head jarring incidents that are intrinsic to the game.

The significance of this research lies in the fact that it makes a meaningful contribution to the development of comprehensive injury prevention programmes. The studies included in this thesis investigate technique-related intrinsic factors where injury is prevented at the expense of performance as well as intrinsic factors where there is potential for both injury prevention and performance to be simultaneously optimised. The cricket pace bowler is prone to injury due to the high load nature of the pace bowling action involving a complex sequence of forceful actions, consisting of practiced, particular movements. Various injury prevention programmes incorporating extrinsic factors have been studied and implemented previously, however the intrinsic factors associated with both injury and performance in pace bowlers have not yet been investigated sufficiently. In this thesis an overview of the literature includes the review of injuries sustained by pace bowlers, factors associated with injury and performance, and the kinematics of the pace bowling action. Premier league (amateur) cricket pace bowlers were recruited for this study. All pace bowlers were injury free at the start of the season. Details around past injuries as well as incidence of injuries were recorded throughout an eight month cricket season. Performance measures, namely ball release speed and accuracy, were measured during execution of the pace bowling action. Included in this thesis are six original papers. The first five papers investigated the association between intrinsic factors, injury and performance, while the sixth paper described abdominal muscle adaptations in the pace bowler. The first paper (Chapter 2) investigated bowlers’ ability to perform lumbo-pelvic movement control, static and dynamic balance tests at the start and at the end of a 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 (SLBT) (p=0.03) and the star excursion balance test (SEBT) (p=0.02) as measured at the start of the season, was better in bowlers who did not sustain an injury during the season. Paper 2 (Chapter 3) investigated 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 of the cricket pace bowling action in relation to previous injury and injury sustained during the cricket season under review. Lumbar reposition error in the sagittal plane (flexion-extension) was between 1.48˚ and 1.82˚ and in the frontal plane (left-right lateral flexion) it was between 0.81˚ and 0.88˚. Lumbar reposition error, as measured in two planes and in three different positions, was associated with self-reported general injuries, injuries sustained during the bowling action and especially, low back injury sustained in the past (p<0.05). From findings indicated in Papers 1, 2 and 3 (Chapters 2, 3 and 4) it can be postulated that if static balance, dynamic balance and lumbar proprioception can be improved in pace bowlers, their risk of lumbar injury may be reduced. Paper 3 and 4 (Chapter 4 and 5) investigated the relationship between kinematic angles as measured in the power phase of the pace bowling action and injury, as well as performance, respectively. In Paper 3 (Chapter 4) a difference was found between lumbar spine lateral flexion positioning (p=0.02) at the start compared to at the end of the season in injured pace bowlers. The range of flexion between front foot placement and ball release at L1 is much greater in the non-injured group than in the injured group as measured at the end of the season (p=0.03). Bowlers who did not sustain an injury during the season displayed a larger degree of absolute flexion at the start of the season than those who sustained an injury (p=0.02). Findings from Paper 4 (Chapter 5) are that the following absolute angles were positively correlated with higher ball release speeds at the start of the season: a more extended knee angle (p=0.037), a larger arm to thorax angle (p<0.0001), larger L1 (p=0.01), T10 (p<0.0001) and T7 (p<0.0001) segmental spinal lateral flexion and more global trunk left rotation (p=0.02). Paper 3 and 4 (Chapter 4 and 5) thus show that low back flexion and lateral flexion, and front knee kinematics, as found in the power phase of the pace bowling action, are associated with and may predict lower quarter injuries and performance outcomes in cricket pace bowlers. The fifth paper (Chapter 6) hypothesised that correlations between front knee angle, knee reposition error, as a measure of proprioception, and ball release speed should be present, however no such correlation could be established. The correlations between joint reposition error in 140˚ of knee extension (r=0.06), 160˚ of knee extension (r=0.30), front foot placement (r=0.22) and ball release (r=0.23) positions were not statistically significant (p>0.05). Furthermore, correlations between knee position error and reproduced knee angles were also not statistically significant (r=-0.35 to r=0.09; p>0.05). It was concluded that static knee joint position sense is not associated with dynamic knee angle during the bowling action, or with ball release speed and that dynamic mechanisms may contribute to knee angles and bowling speeds. The sixth study (Chapter 7) investigated and highlighted the possible muscle adaptations in absolute muscle thickness and activity as a consequence of the asymmetrical bowling action. The absolute thickness of the non-dominant obliquus abdominis internus (OI) was higher than that of the dominant OI at the start (p<0.0001) as well as at the end of the cricket season (p<0.0001). At the start of the season the percentage change during the abdominal drawing in manoeuvre, thus a measure of muscle activity, was higher for the non-dominant OI than for the dominant OI (p=0.02). Absolute thickness of the dominant obliquus abdominis externus (OE) at rest was significantly higher at the end of the season compared with at the start of the season (p<0.0001). During right side active straight leg raise, the activity of the left transversus abdominis (TA) was significantly higher than that of the right TA during left side active straight leg raise (p=0.03) when measured at the end of the season. These asymmetries in abdominal muscle thickness and activity may contribute to the predisposition to low back injury in cricket pace bowlers or may occur in an attempt to protect the pace bowler against injury. In conclusion, the high load nature of the pace bowling action allows for high ball release speeds to be attained but at the same time renders the pace bowler vulnerable to injury. Intrinsic factors found to be associated with both lower quarter injury and performance should be appropriately incorporated into injury prevention programmes in order to prevent the occurrence of injuries in the presence of the high load nature of the pace bowling action. Further research needs to be conducted on the effectiveness of these injury prevention programmes to prevent injury amongst pace bowlers.

No description available.