Descriptive epidemiology of Australian football injuries presenting to sports medicine clinics

Sports injury prevention has been the focus of a number of recent public health initiatives due to the acknowledgement that sports injuries are a significant public health problem in Australia Whilst Australian football is one of the most popular participation sports in the country, only very limited data is available about football injuries The majority of sports injury data available for this sport is from hospital emergency departments and elite-level injury surveillance Overall there is a paucity of data from treatment settings other than hospitals In particular, there is a lack of information about the injuries sustained by community-level, junior and recreational Australian football participants. One good potential source of football injury data is sports medicine clinics. Analysis of injury presentations to sports medicine clinics was undertaken to provide a detailed description of the epidemiology of Australian football injuries that present to this treatment setting and to determine the implications for injury prevention in this sport. In addition, the data from sports medicine clinics was compared with existing sources of Australian football injury data to determine how representative sports medicine clinic data is of other football injury data sources and to provide recommendations for future injury surveillance n Australian football. The results contained in this thesis show that Australian football is the sport most associated with injury presentation at sports medicine clinics. The majority of injured Australian football players presenting to sports medicine clinics are community-level or junior participants which suggests that sports medicine clinics are a good source of information on the injuries sustained by sub-elite football participants. Competition is the most common context in which Australian football players presenting to sports medicine clinics are injured. The major causes of injuries to Australian football players are being struck by another player, collisions and overuse. Injuries to Australian football players predominantly involve the lower limb. Adult players, players who stopped participating immediately after noticing their injury and players with overuse injuries are the most likely to sustain a more severe injury (i.e. more than four weeks before a full return to football participation and a moderate/significant amount of treatment expected). The least experienced players (five or less years of participation) are more likely to require a significant amount of treatment than the more experienced players. The prevention of lower limb injuries, injuries caused by body contact and injuries caused by overuse should be a priority for injury prevention research in Australian football due to the predominance of these injury types in the pattern of Australian football injuries Additionally, adult players, as a group, should be a focus of injury prevention activities in Australian football due to the association between age and injury severity. Overall, the pattern of Australian football injuries presenting to sports medicine clinics appears to be different than reported by club-based and hospital emergency department injury surveillance activities. However, detailed comparison of sports medicine clinic Australian football data with other sources of Australian football injury data is difficult due to the variable methods of collecting and reporting injury information used by hospital emergency department and club-based injury surveillance activities. The development of a standardised method for collecting and reporting injury data in Australian football is strongly recommended to overcome the existing limitations of data collection in this sport. In summary, sports medicine clinics provide a rich source of Australian football injury data, especially from the community and junior levels of participation. The inclusion of sports medicine clinic data provides a broader epidemiological picture of Australian football injuries. This broader understanding of the pattern of Australian football injuries provides a better basis for the development of injury prevention measures in this sport.

Older adults' neuromuscular adaptations to resistence training and effects on challenging gait tasks

Community locomotion is threatened when older individuals are required to negotiate obstacles, which place considerable stress on the musculoskeletal system. The vulnerability of older adults during challenging locomotor tasks is further compromised by age-related strength decline and muscle atrophy. The first study in this investigation determined the relationship between the major muscle groups of the lower body and challenging locomotor tasks commonly found in the community environment of older adults. Twenty-nine females and sixteen males aged between 62 and 88 years old (68.2 ±6.5) were tested for the maximal voluntary contraction (MVC) strength of the knee extensors and 1-RM for the hip extensors, flexors, adductors, abductors, knee extensors and flexors and ankle plantar flexors. Temporal measurements of an obstacle course comprising four gait tasks set at three challenging levels were taken. The relationship between strength and the obstacle course dependent measures was explored using linear regression models. Significant associations (p≤0.05) between all the strength measures and the gait performances were found. The correlation values between strength and obstructed gait (r = 0.356-0.554) and the percentage of the variance explained by strength (R2 = 13%-31%), increased as a function of the challenging levels, especially for the stepping over and on and off conditions. While the difficulty of community older adults to negotiate obstacles cannot be attributed to a single causal pathway, the findings of the first study showed that strength is a critical requirement. That the magnitude of the association increased as a function of the challenging levels, suggests that interventions aimed at improving strength would potentially be effective in helping community older adults to negotiate environmental gait challenges. In view of the findings of the first study, a second investigation determined the effectiveness of a progressive resistance-training program on obstructed gait tasks measured under specific laboratory conditions and on an obstacle course mimicking a number of environmental challenges. The time courses of strength gains and neuromuscular mechanisms underpinning the exercise-induced strength improvements in community-dwelling older adults were also investigated. The obstructed gait conditions included stepping over an obstacle, on and off a raised surface, across an obstacle and foot targeting. Forty-three community-living adults with a mean age of 68 years (control =14 and experimental=29) completed a 24-week progressive resistance training program designed to improve strength and induce hypertrophy in the major muscles of the lower body. Specific laboratory gait kinetics and kinematics and temporal measures taken on the obstacle course were measured. Lean tissue mass and muscle activation of the lower body muscle groups were assessed. The MVC strength of the knee extensors and 1-RM of the hip extension, hip flexion, knee extension, knee flexion and ankle plantar flexion were measured. A 25% increase on the MVC of the knee extensors (p≤0.05) was reported in the training group. Gains ranging between 197% and 285% were recorded for the 1-RM exercises in the trained subjects with significant improvements found throughout the study (p≤0.05). The exercise-induced strength gains were mediated by hypertrophic and neural factors as shown by 8.7% and 27.7% increases (p≤0.05) in lean tissue mass and integrated electromyographic activity, respectively. Strength gains were accompanied by increases in crossing velocity, stride length and reductions in stride duration, stance and swing time for all gait tasks except for the foot targeting condition. Specific kinematic variables associated with safe obstacle traverse such as vertical obstacle heel clearance, limb flexion, horizontal foot placements prior to and at post obstacle crossing and landing velocities resulted in an improved crossing strategy in the experimental subjects. Significant increases in the vertical and anterior-posterior ground reaction forces accompanied the changes in the gait variables. While further long-term prospective studies of falls rates would be needed to confirm the benefits of lower limb enhanced strength, the findings of the present study provide conclusive evidence of significant improvements to gait efficiency associated with a systematic resistance-training program. It appears, however, that enhanced lower body strength has limited effects on gait tasks involving a dynamic balance component. In addition, due to the larger strength-induced increases in voluntary activation of the leg muscle compared to relatively smaller gains in lean tissue mass, neural adaptations appear to play a greater contributing role in explaining strength gains during the current resistance training protocol.

Severely compromised quality of life in women and those of lower socioeconomic status waiting for joint replacement surgery

Objective
To determine health-related quality of life (HRQOL), psychological distress, physical function, and self efficacy in persons waiting for lower-limb joint replacement surgery.

Methods
A total of 214 patients on a waiting list for unilateral primary total knee or hip replacement at a large Australian public teaching hospital completed questionnaires after entry to the list. HRQOL and psychological distress were compared with available population norms.

Results
Average HRQOL was extremely poor (mean ± SD 0.39 ± 0.24) and much lower (>2 SD) than the population norm. Near death-equivalent HRQOL or worse than death-equivalent HRQOL were reported by 15% of participants. High or very high psychological distress was up to 5 times more prevalent in the waiting list sample (relative risk 5.4 for participants ages 75 years and older; 95% confidence interval 3.3, 9.0). Women had significantly lower HRQOL, self efficacy, and physical function scores than men. After adjusting for age and sex, significant socioeconomic disparities were also found. Participants who received the lowest income had the poorest HRQOL; those with the least education or the lowest income had the highest psychological distress. Low self efficacy was moderately associated with poor HRQOL (r = 0.49, P < 0.001) and more strongly associated with high psychological distress (r = -0.55, P < 0.001).

Conclusion
Patients waiting for joint replacement have very poor HRQOL and high psychological distress, especially women and those from lower socioeconomic backgrounds. Lengthy waiting lists mean patients can experience extended and potentially avoidable morbidity. Interventions to address psychological distress and self efficacy could reduce this burden and should target women and lower socioeconomic groups.