Biomedical subjects

J C Brückner

Publications and source records attributed to J C Brückner.

3 recordsLinked to original sources

PubMed1986

The energetics of endurance running.

Maximal O2 consumption (VO2max) and energy cost of running per unit distance (C) were determined on the treadmill in 36 male amateur runners (17 to 52 years) who had taken part in a marathon (42.195 km) or semi-marathon (21 km), their performance times varying from 1.49 to 226 and from 84 to 131 min, respectively. VO2max was significantly (2p less than 0.001) greater in the marathon runners (60.6 vs 52.1 ml . kg-1 . min-1) while C was the same in both groups (0.179 +/- 0.017, S.D., mlO2 . kg-1 . m-1 above resting), and independent of treadmill speed. It can be shown that the maximal theoretical speed in endurance running (vEND) is set by VO2max, its maximal sustainable fraction (F), and C, as described by: vEND = F . VO2max . C-1. Since F was estimated from the individual time of performance, vEND could be calculated. The average speed of performance (vMIG) and vEND (m . s-1) were found to be linearly correlated: vMIG = 1.12 + 0.64 vEND (r2 = 0.72; n = 36). The variability of vMIG explained by vEND, as measured by r2, is greater than that calculated from any one regression between vMIG and VO2max (r2 = 0.51), F . VO2max (r2 = 0.58), or VO2max . C-1 (r2 = 0.63). The mean ratio of observed (vMIG) to theoretical (vEND) speeds amounted to 0.947 +/- 0.076 and increased to 0.978 +/- 0.079 (+/- S.D.; n = 36) when the effects of air resistance were taken into account. It is concluded that vEND = F . VO2max . C-1 is a satisfactory quantitative description of the energetics of endurance running.

Adolescent↗

PubMed1986

Multiple complications after internal jugular vein catheterisation.

We report a case of a young female who developed multiple life threatening complications after a single internal jugular vein catheterisation. They consisted of pleural misplacement of the catheter, massive haemorrhage with cardiovascular collapse following catheter removal, and development of arteriovenous fistula, diagnosed 18 months later.

Adolescent↗

PubMed1986

Physiological profile of world-class high-altitude climbers.

The functional characteristics of six world-class high-altitude mountaineers were assessed 2-12 mo after the last high-altitude climb. Each climber on one or several occasions had reached altitudes of 8,500 m or above without supplementary O2. Static and dynamic lung volumes and right and left echocardiographic measurements were found to be within normal limits of sedentary controls (SC). Muscle fiber distribution was 70% type I, 22% type IIa, and 7% type IIb. Mean muscle fiber cross-sectional area was significantly smaller than that of SC (-15%) and of long-distance runners (LDR, -51%). The number of capillaries per unit cross-sectional area was significantly greater than that of SC (+ 40%). Total mitochondrial volume was not significantly different from that of SC, but its subsarcolemmal component was equal to that of LDR. Average maximal O2 consumption was 60 +/- 6 ml X kg-1 X min-1, which is between the values of SC and LDR. Average maximal anaerobic power was 28 +/- 2.5 W X kg-1, which is equal to that of SC and 40% lower that that of competitive high jumpers. All subjects were characterized by resting hyperventilation both in normoxia and in moderate (inspired O2 partial pressure = 77 Torr) hypoxia resulting in higher oxyhemoglobin saturation levels in hypoxia. The ventilatory response to four tidal volumes of pure O2 was similar to that of SC. It is concluded that elite high-altitude climbers do not have physiological adaptations to high altitude that justify their unique performance.

Adaptation, Physiological↗