Profiling Sprint Mechanics by Leg Preference and Position in Rugby Union Athletes.

Lower-extremity power characteristics are central to performance in rugby. However little is known regarding the effects of leg preference and playing position on sprint mechanics. The purpose of this study was to profile sprint kinetics and kinematics in rugby union athletes and compare between legs and between positions. Thirty male academy-level rugby union athletes, separated into forwards (n=15) and backs (n=15), participated in this cross-sectional analysis. Non-motorised treadmill ergometry was used to evaluate peak relative vertical (FV) and horizontal (FH) force and peak relative power (Pmax) of the preferred and non-preferred legs during maximal sprinting. The non-preferred leg of the forwards produced less FV, FH and Pmax than the preferred leg during acceleration (ES=-0.32, - 0.58 and - 0.67) and maximal velocity (ES=- 0.50, - 0.65 and - 0.60). Backs produced more FV, FH and Pmax than the forwards during initial acceleration (ES=0.51, 1.58 and 1.30) but less at maximal velocity (ES=- 0.74, -0.79 and - 0.81). Backs had faster split times at 2, 5, 10 and 15 m (ES=-1.03, -0.82, -0.63 and -0.50) but slower times at 35 and 40 m (ES=0.78 and 1.10) compared with forwards. Forwards produced larger sprint kinetics compared with backs, but also larger lower-extremity imbalances; potentially reducing sprint efficiency and/or increasing injury risk.

An effective conscious animal model of atrial fibrillation.

In 11 fully conscious dogs with chronically implanted spicardial electrodes, 50 Hz sine-wave electrical stimulation of the left atrium reliably and repeatedly produced an arrhythmia which was indistinguishable from atrial fibrillation in terms of its ECG appearance, the statistical properties of the ventricular response and responses to a number of pharmacological agents. In five of the 11 preparations this arrhythmia consistently persisted for periods in excess of 10 min following the cessation of stimulation, indicating an intrinsic cardiac basis for the arrhythmia and suggesting that it is true atrial fibrillation. A close correlation between the ventricular response to this arrhythmia and the degree of atrioventricular conductivity, together with the observation that dramatic changes can occur in ventricular responses without corresponding changes in atrial activity, suggest that the ventricular response is mainly a function of the atrio-ventricular conducting system. The experimental model described is useful for the study of both short and long term drug action no atrial fibrillation and for the evaluation of methods used therapeutically in attempts to terminate episodes of paroxysmal atrial fibrillation.

Continuous, non-invasive measurement of the haemodynamic response to submaximal exercise in patients with diabetes mellitus: evidence of impaired cardiac reserve and peripheral vascular response.

BACKGROUND: Reduced exercise capacity in diabetics has been attributed to limitations in cardiac function and microvascular dysfunction leading to impaired oxygen supply and nutritive perfusion to exercising muscles. OBJECTIVE: To study changes in cardiac function and microvascular utilisation during exercise in diabetic individuals compared to age-matched controls. METHODS: Diabetics with glycosylated haemoglobin (HbA(1c)) < 8 (n = 31), diabetics with HbA(1c) > or = 8 (n = 38) and age-matched non-diabetic controls (n = 32) performed exercise at 50 W for 10 minutes followed by recovery, with continuous monitoring of cardiac function by impedance cardiography and regional flow and oxygen saturation by laser Doppler and white light spectroscopy. RESULTS: In the diabetics, cardiac reserve during exercise and cardiac overshoot during recovery are significantly reduced because of reduction in capacity to increase stroke volume. Regional flow to the exercising muscle is reduced and there is also disproportionately greater desaturation of the regional flow. Abnormalities in cardiac function and regional perfusion are related to the severity of diabetes. CONCLUSION: Cardiac response to exercise is attenuated significantly in diabetic individuals. Simultaneously, there is impairment in the regional distribution. These changes could be the harbinger of reduced exercise capacity in diabetics.

Mucinous cystadenoma of the pancreas. Endoscopy as an aid to diagnosis.

Pancreatitis and pancreatic insufficiency have not previously been associated with mucinous cystadenoma of the pancreas. This report describes a patient with a long history of chronic pancreatitis whose course was complicated by obstructive jaundice and cholangitis and pancreatic insufficiency. Endoscopy with retrograde cholangiopancreatography provided the correct diagnosis, and the findings are described.

Serum fluoride concentration and urine osmolality after enflurane and sevoflurane anesthesia in male volunteers.

The purpose of this study was to measure the serum fluoride concentration after enflurane or sevoflurane anesthesia and to compare the effects of prolonged anesthesia with these drugs on renal concentrating function in male volunteers. The study was subdivided into three stages; an ascending dose study of 3.0 and 6.0 minimum alveolar anesthetic concentration (MAC) hours of sevoflurane alone, a 6.0-MAC-hour comparison of enflurane and sevoflurane, and a 9.0-MAC-hour comparison of enflurane and sevoflurane. Renal concentrating function was assessed by an 18-h period of fluid deprivation and the serum fluoride concentration was measured at intervals until 60 h postanesthesia. The maximum serum fluoride concentration was greater in the volunteers exposed to sevoflurane and reached a peak in the 9-MAC-hour sevoflurane group of 36.6 microM (SD 4.3) compared with 27.5 microM (SD 2.6) in the 9-MAC-hour enflurane group. However, the rapid decrease in the serum fluoride concentration after sevoflurane was such that there was no difference between the areas under the fluoride concentration-time curves. There were no significant differences between the median maximum urine osmolalities after enflurane or sevoflurane anesthesia. Prolonged anesthesia with enflurane or sevoflurane is not associated with impaired renal concentrating function despite an increase in the serum fluoride concentration.

Ocular fundus lesions in divers.

Retinal fluorescein angiography was used to examine the ocular fundi of 84 divers. The retinal capillary density at the fovea was low and microaneurysms and small areas of capillary nonperfusion were seen. The divers had significantly more abnormalities of the retinal pigment epithelium than a comparison group of non-divers. Furthermore, the prevalence of fundus abnormality was related to length of diving history. All observed changes were consistent with the obstruction of the retinal and choroidal circulations. Such obstruction could be due either to intravascular bubble formation during decompression, or to altered behaviour of blood constituents and blood vessels in hyperbaric conditions.