Objective-To examine regional changes in the fluid content of human intervertebral discs by comparing sagittal plane "profiles" of hydration before and after mechanical loading.

Objectives: To investigate the effects of strenuous exercise on commonly used biochemical and haematological variables in subjects running the 2002 London marathon. Methods: 34 healthy volunteers (7 female, 27 male) were recruited for the study. Blood was taken before the start (at registration) and immediately after completion of the marathon. Samples were analysed for urea and electrolytes, liver function tests, creatine kinase (CK), CK-MB isoenzyme, myoglobin, troponin I, full blood count, a clotting screen, and D-dimers. The results before and after exercise were compared. Pearson's correlation coefficients were calculated for all variables. Results: Significant increases were found in CK, CK-MB, aspartate aminotransferase (AST), lactate dehydrogenase (LDH), and myoglobin following the marathon. However, there was no significant change in the level of troponin I. There was also evidence of activation of the coagulation and fibrinolytic cascades following the marathon, with a reduction in activated partial thromboplastin time, a reduction in fibrinogen, and an increase in D-dimers. Conclusions: The results confirm previous individual studies on marathon running and the biochemical and haematological tests routinely carried out in hospital. These are affected by prolonged exercise, and ''abnormal'' results in these tests may be normal after prolonged exercise and therefore not diagnostic of a disease process. The results of investigations in patients who have been exercising should be interpreted with caution.

Links between overuse injury prevalence in triathletes training for 1.5km, 40km, 10km triathlon and both intrinsic and extrinsic factors were assessed in 12 Elite, 17 Development and 87 male Club triathletes by a five year retrospective questionnaire. Elite, Development and Club triathletes differed in training mileage, duration and number of workouts but not in overall injury prevalence, distribution, and severity. Overuse injury occurred in 75.0% of male Elite Squad, 75.0% of Development Squad and 56.3% of Club athletes with 1.9-2.9 sites affected. The most common injuries - the achilles tendon (10.3-17.9%), lower back (15.8-17.9%) and knee (14.2-21.9% of injuries) - were also among the most severe. Running injuries accounted for more of the total number of injuries than cycling injuries in Elite (62.1 % vs 34.5%, p<0.05), Development (64.3% vs 25.0%, p<0.05) and Club triathletes (58.7% vs 15.9%, p<0.05). The number of running injuries sustained correlated with triathlon training distance, cycling distance (p<0.03), swimming distance (p<0.01), number of triathlon workouts (p<0.03) and number of running sessions (p<0.03) within one weeks race training. The number of overuse injuries sustained during cycling correlated with time spent running and cycling.

This paper evaluates a technique for measuring the distribution of compressive stress within cadaveric intervertebral discs. A strain-gauged pressure transducer, side-mounted near the tip of a 1.3 mm diameter needle, was inserted into cubes of disc tissue and into intact discs. Regardless of the position and orientation of the transducer within the tissue or disc, its output was found to be proportional to the compressive force applied to the specimen. The distribution of compressive stress was measured by pulling the instrumented needle through the specimen and the resulting stress profiles were reproducible to within 20 per cent. Profiles obtained at different applied loads showed a similar distribution of stress within the disc, suggesting that the compressive stress at any location and direction increased in proportion to the applied load. Since transducer output was also proportional to applied load, it was reasoned that it must be proportional to compressive stress within the disc. The average vertical compressive stresses acting on various regions within a disc were calculated from the stress profiles and multiplied by the cross-sectional area of each region: the resulting force was then compared with the known applied force in order to assess the calibration coefficient of the transducer. Agreement between the two forces was good, indicating that the calibration coefficient established in a saline bath was applicable to disc tissues also. However, artifactual stress peaks could be generated if the transducer was pulled across a bony asperity. It is concluded that the transducer measures the mean compressive stress acting upon it within disc tissues. Errors associated with the technique are small compared to differences in stress distributions which occur naturally, for example when intervertebral discs are loaded to simulate different postures in a living person.

Objectives: To assess the demographics and training characteristics of adventure racing athletes in the United Kingdom, the prevalence and anatomical distribution of hazardous encounter, and overuse injury in this population, and the effects these injuries have on training. Methods: A retrospective training and injury questionnaire for the previous 18 months was distributed to 300 adventure racing athletes at two national race meetings. The definition of an injury was ''any musculoskeletal problem causing a stop in training for at least one day, reduction in training mileage, taking of medicine, or seeking of medical aid.'' Results: The data were derived from the responses of 223 athletes. Advanced level athletes did 11 (4) sessions and 17 (8) hours of training a week (mean (SD)). An injury was reported in the previous 18 months by 73% of the respondents. The most common site of acute injury was the ankle (23%) and of chronic/overuse injury, the knee (30%), followed by the lower back, shin, and Achilles tendon (12% each). There were significant correlations (p,0.01) between the hours spent cycling per week and number of acute injuries, and between the number of days off per week and number of chronic/overuse injuries. Injuries resulted in an average of 23 days training cessation or reduction. Conclusions: Acute injuries were sustained mainly as a result of the nature of the terrain over which athletes train and compete. In overuse injuries lack of adequate rest days was a significant contributing factor. Only a small proportion of training time was spent developing flexibility and core stability.