Changes in acid-base status of marathon runners during an incremental field test Relationship to mean competitive marathon velocity

Four top-class runners who regularly performed marathon and long-distance races participated in this study. They performed a graded field test on an artificial running track within a few weeks of a competitive marathon. The test consisted of five separate bouts of running. Each period lasted 6 min with an intervening 2-min rest bout during which arterialized capillary blood samples were taken. Blood was analysed for pH, partial pressure of oxygen and carbon dioxide (P0₂ and PCO₂) and lactate concentration ([la^–]_b). The values of base excess (BE) and bicarbonate concentration ([HCO₃ ^–]) were calculated. The exercise intensity during the test was regulated by the runners themselves. The subjects were asked to perform the first bout of running at a constant heart rate f _c which was 50 beats · min^–1 below their own maximal f _c. Every subsequent bout, each of which lasted 6 min, was performed with an increment of 10 beats · min^–1 as the target f _c. Thus the last, the fifth run, was planned to be performed with fc amounting to 10 beats · min^–1 less than their maximal f _c. The results from these runners showed that the blood pH changed very little in the bouts performed at a running speed below 100% of mean marathon velocity ( _m). However, once _mwas exceeded, there were marked changes in acid-base status. In the bouts performed at a velocity above the _mthere was a marked increase in [la^–]_b and a significant decrease in pH, [HCO₃ ^–], BE and PCO₂. The average marathon velocity ( _m) was 18.46 (SD 0.32) km·h^–1. The [la^–]_b at a mean running velocity of 97.1 (SD 0.8) % of _mwas 2.33 (SD 1.33) mmol ·l^–1 which, compared with a value at rest of 1.50 (SD 0.60) mmol·l^–1, was not significantly higher. However, when running velocity exceeded the vm by only 3.6 (SD 1.9) %, the [la^–]b increased to 6.94 (SD 2.48) mmol·l-1 (P<0.05 vs rest). We concluded from our study that the highest running velocity at which the blood pH still remained constant in relation to the value at rest and the speed of the run at which [la^–]_b began to increase significantly above the value at rest is a sensitive indicator of capacity for marathon running.     

Regulating Consent to Organ and Embryo Donation The Legal Dimensions of the Problem

As rational adults, we are free to elect what is (or is not) done to our bodies. However, this strong freedom does not extend to the borders of life. Control over the uses of our biological material is constrained and uncertain at law. Our article examines the legal condition of embryos and organs: how law conceptualises them and regulates their uses.     

Psychiatric Ethics and a Politics of Compassion The Case of Detained Asylum Seekers in Australia

Australia has one of the harshest regimes for the processing of asylum seekers, people who have applied for refugee status but are still awaiting an answer. It has received sharp rebuke for its policies from international human rights bodies but continues to exercise its resolve to protect its borders from those seeking protection. One means of doing so is the detention of asylum seekers who arrive in Australia by boat. Health care providers who care for asylum seekers in these conditions experience a conflict of “dual loyalty,” whereby their role in preserving and maintaining the health of patients can run counter to their employment in detention facilities. Many psychiatrists who have worked in the detention setting engage in forms of political activism in order to change the process of seeking refuge.     

Skeletal muscle damage during tourniquet-induced ischaemia The initial step towards atrophy after orthopaedic surgery?

Muscle biopsies from the vastus lateralis muscle of patients who had undergone anterior cruciate ligament surgery under conditions of tourniquet-induced ischaemia were examined under the electron microscope at different periods of time up to 90 min of ischaemia. The severity of the alterations in ultrastructure appeared to depend on the period of ischaemia. The pathological changes consisted of accumulation of lysosomes, persistent intrafibre oedema, and some extracellular oedema. Signs of fibre necrosis were found after 90 min of ischaemia. Capillary ultrastructure was only altered with regard to some swelling of the endothelium and marked thickening of the basement membrane. It was concluded that skeletal muscle could be severely affected even during relatively short periods of ischaemia, which might facilitate the development of muscle atrophy during immobilization after orthopaedic surgery.     

The danger of an inadequate water intake during prolonged exercise A novel concept re-visited

To prevent thermal injuries during distance running, the American College of Sports Medicine proposes that between 0.83 and 1.65 l of water should be ingested each hour during prolonged exercise. Yet such high rates of fluid intake have been reported to cause water intoxication. To establish the freely-chosen rates of fluid intake during prolonged competitive exercise, we measured fluid intake during, body weight before and after, and rectal temperature after competition in a total of 102 runners and 91 canoeists competing in events lasting from 170-340 min. Fluid intakes during competition ranged from 0.29-0.62 l.h-1; rates of water loss ranged from 0.69-1.27 l.h-1 in the runners; values were lower in the canoeists. Mean post-race rectal temperatures ranged from 38.0-39.0 degrees C. There was no relationship between the degree of dehydration and post-race rectal temperature. We conclude that hyperthermia is uncommon in prolonged competitive events held in mild environmental conditions, and that exercise intensity, not the level of dehydration, is probably the most important factor determining the postexercise rectal temperature. During prolonged exercise in mild environmental conditions, a fluid intake of 0.5 l.h-1 will prevent significant dehydration in the majority of athletes.     

IUMS News International Union of Microbiological Societies Newsletter

IUMS NewsInternational Union of Microbiological Societies Newsletter     

IUMS News International Union of Microbiological Societies Newsletter

IUMS NewsInternational Union of Microbiological Societies Newsletter     

Dispersal of adult female fig wasps 1. Arrivals and departures

Ficus burtt-davyi, like most other fig species (Ficus, Moraceae), is exclusively pollinated by its own unique species of fig wasp, in this caseElisabethiella baijnathi (Chalcidoidea, Agaonidae). Because fig crop development on any one tree is usually synchronised, the small and short-lived female wasps have to migrate and find other trees bearing figs which are at suitable stage of development for oviposition. However, the likelihood of successful location and subsequent arrival at a new host tree is dependent on distance and the effect of environmental factors such as wind and temperature. This study examines the relationship between ambient temperatures and the timing of fig wasps emergence from their natal figs and the commencement of their dispersal flight. The behaviour of the wasps arriving at figs which were ready to be pollinated was also examined. The female wasps did not appear to distinguish between the figs and other parts of the tree when in flight. However, after landing on the tree their search for figs was more directed as they visited more figs than leaves. Short-range recognition of figs appears to be by contact chemo-reception, but the wasps showed a preference for entering figs which did not already contain a female wasp.     

Eccentric and concentric torque-velocity relationships during arm flexion and extension Influence of strength level

Forty men were tested with a computerized dynamometer for concentric and eccentric torques during arm flexion and extension at 0.52, 1.57, and 2.09 rad.s-1. Based on the summed concentric and eccentric torque scores, subjects were placed into a high strength (HS) or low strength (LS) group. The eccentric and concentric segments of the torque-velocity curves (TVCs) were generated using peak torque and constant-angle torque (CAT) at 1.57 and 2.36 rad. Angle of peak torque was also recorded. Compared to LS, HS had significantly greater estimated lean body mass (+10.2 kg) and approximately 25% greater average torque output. Reliability of the peak torque scores on 2 days in 20 subjects was r greater than or equal to 0.85. The difference between observed torques and the mathematically computed criterion torque scores averaged 1% for three validation loads that ranged from 11.4 to 90.4 kg. Statistical analysis revealed that torque output in LS plateaued at low concentric velocities and was also flattened with increasing eccentric velocities. Conversely, torque output for HS increased with decreasing concentric velocities and increased with increasing eccentric velocities. The method of plotting the TVCs for peak or CAT did not influence the pattern of TVC. Eccentric flexion peak torque occurred at a significantly shorter muscle length (1.88 rad) than concentric torque (2.12 rad). This difference was also present for extension; it was 1.88 rad for eccentric and 2.03 rad for concentric torque.(ABSTRACT TRUNCATED AT 250 WORDS)