Comparison of hypoxanthine and lactate as indicators of hypoxia in man

Peer Reviewe

Static and Dynamic Lung Volumes in Swimmers and Their Ventilatory Response to Maximal Exercise

Purpose While the static and dynamic lung volumes of active swimmers is often greater than the predicted volume of similarly active non-swimmers, little is known if their ventilatory response to exercise is also different. Methods Three groups of anthropometrically matched male adults were recruited, daily active swimmers (n = 15), daily active in fields sport (Rugby and Football) (n = 15), and recreationally active (n = 15). Forced vital capacity (FVC), forced expiratory volume in 1 s (FEV1), and maximal voluntary ventilation (MVV) was measured before and after exercise to volitional exhaustion. Results Swimmers had significantly larger FVC (6.2 ± 0.6 l, 109 ± 9% pred) than the other groups (5.6 ± 0.5 l, 106 ± 13% pred, 5.5 ± 0.8, 99% pred, the sportsmen and recreational groups, respectively). FEV1 and MVV were not different. While at peak exercise, all groups reached their ventilatory reserve (around 20%), the swimmers had a greater minute ventilation rate than the recreational group (146 ± 19 vs 120 ± 87 l/min), delivering this volume by breathing deeper and slower. Conclusions The swimmers utilised their larger static volumes (FVC) differently during exercise by meeting their ventilation volume through long and deep breaths

Safety vs. reputation: risk controversies in emerging policy networks regarding school safety in the Netherlands

This article deals with risk controversies in emerging policy networks regarding school safety in the Netherlands. It offers a grounded account of the interpretations of school risks and safety measures by the various stakeholders of the policy network, in particular, schools, local government and the police. Theoretically, policy networks are conceived as mediating between the structural conditions of the risk-society and the culture of fear on the one hand and the institution of safety standards on the organizational level of schools on the other hand. It is argued that in the low-risk context of schools, it is particularly important to take into account the soft, cultural side of safety next to the hard, material side of safety. This distinction also accounts for the ambiguities and controversies over school risks. A further conclusion is that in this network a lack of local leadership seems to hinder the development of firm safety measures. Overall, this article highlights the paradox between a concern for safety and a concern for a schools reputation. © 2012 Taylor & Francis

Drivers for international innovation activities in developed and emerging countries

This paper aims to shed light on firm specific drivers that lead firms to internationalise their innovation activities. The paper draws a comprehensive picture of driving forces by including firm capabilities, characteristics of the firm’s competitive environment and the influence of innovation obstacles in the home country. In particular, the role of the potential driving forces is tested on the probability to carry out different innovative activities abroad (R&D, design/conception of new products, manufacturing of innovative products and implementation of new processes). In a second step these driving forces are used to observe their impact on the decision to locate innovation activities in various countries and regions (China, Eastern Europe, Western Europe and North America) as well as in groups of countries with similar levels of knowledge (country clubs). The analysis is based on the Mannheim Innovation Panel survey which represents the German CIS (Community Innovation Survey) contribution. Two survey waves are combined and result in a sample of about 1400 firms. The results show that the decision to perform innovation activities abroad is mainly driven by organisational capabilities such as absorptive capacities, international experience and existing technological competences of the respective firm. Innovation barriers at the German home base such as lack of labour and high innovation costs foster the set up of later-stage innovation activities abroad while the lack of demand demonstrates a barrier to the internationalisation decision for the development and manufacturing of new products. Location decisions receive the strongest influencing effects from the international experience of the firm. Firms which innovate in developing countries seem to require a more extensive level of international experience by international R&D cooperation

Drivers and Effects of Internationalising Innovation by SMEs

This paper investigates the drivers and the effects of the internationalisation of innovation activities in SMEs based on a large data set of German firms covering the period 2002-2007. We look at different stages of the innovation process (R&D, design, production and sales of new products, and implementation of new processes) and explore the role of internal resources, home market competition and innovationrelated location advantages for an SME’s decision to engage in innovation activities abroad. By linking international innovation activities to firm growth in the home market we try to identify likely internationalisation effects at the firm level. The results show that export experience and experience in knowledge protection are highly important for international innovation activities of SMEs. Fierce home market competition turns out to be rather an obstacle than a driver. High innovation costs stimulate internationalisation of non-R&D innovation activities, and shortage of qualified labour expels production of new products. R&D activities abroad and exports of new products spur firm growth in the home market while there are no negative effects on home market growth from shifting production of new products abroad

Reliability of measurements with Innocor during exercise

Cardiac output represents the primary determinant of cardiovascular function. Therefore, understanding how cardiac output is regulated during exercise is crucial. A recently developed tool for determining cardiac output is the Innocor rebreathing system, which also incorporates an ergospirometry unit. So far, Innocor's test-retest reliability under exercise conditions has not been determined in healthy participants. Therefore, 15 male and 15 female healthy participants [30.6 y (SD 4.5); 68.0 kg (SD 10.5)] performed 2 test sessions, each consisting of 2 graded exercise tests to volitional exhaustion. We determined intra- and inter-session reliability of cardiac output, oxygen consumption, carbon dioxide output, and ventilation at 130 W and at peak exercise. For cardiac output, we found averaged coefficients of variation ranging from 4.3 (intra-session, 130 W) to 10.0% (inter-session, rest). For oxygen consumption, coefficients of variation ranged from 3.4 (intra-session, peak) to 5.7% (inter-session, peak). Coefficients of variation for carbon dioxide output were between 4.4 (intra-session, peak) and 6.6% (inter-session, peak), and for ventilation between 5.1 (intra-session, 130 W) and 7.0% (intra-session, peak). Innocor delivers safe and reliable measurements of cardiac output, gas exchange, and ventilation. Therefore, Innocor can be used to assess these parameters in exercise physiology studies as well as in performance diagnostics

Time to exhaustion at maximal lactate steady state is similar for cycling and running in moderately trained subjects

We compared time to exhaustion (t (lim)) at maximal lactate steady state (MLSS) between cycling and running, investigated if oxygen consumption, ventilation, blood lactate concentration, and perceived exertion differ between the exercise modes, and established whether MLSS can be determined for cycling and running using the same criteria. MLSS was determined in 15 moderately trained men (30 +/- 6 years, 77 +/- 6 kg) by several constant-load tests to exhaustion in cycling and running. Heart rate, oxygen consumption, and ventilation were recorded continuously. Blood lactate concentration and perceived exertion were measured every 5 min. t (lim) (37.7 +/- 8.9 vs. 34.4 +/- 5.4 min) and perceived exertion (7.2 +/- 1.7 vs. 7.2 +/- 1.5) were similar for cycling and running. Heart rate (165 +/- 8 vs. 175 +/- 10 min(-1); P < 0.01), oxygen consumption (3.1 +/- 0.3 vs. 3.4 +/- 0.3 l min(-1); P < 0.001) and ventilation (93 +/- 12 vs. 103 +/- 16 l min(-1); P < 0.01) were lower for cycling compared to running, respectively, whereas blood lactate concentration (5.6 +/- 1.7 vs. 4.3 +/- 1.3 mmol l(-1); P < 0.05) was higher for cycling. t (lim) at MLSS is similar for cycling and running, despite absolute differences in heart rate, ventilation, blood lactate concentration, and oxygen consumption. This may be explained by the relatively equal cardiorespiratory demand at MLSS. Additionally, the similar t (lim) for cycling and running allows the same criteria to be used for determining MLSS in both exercise modes

Rate of erythropoietin formation in humans in response to acute hypobaric hypoxia

This study was carried out to investigate the early changes in erythropoietin (EPO) formation in humans in response to hypoxia. Six volunteers were exposed to simulated altitudes of 3,000 and 4,000 m in a decompression chamber for 5.5 h. EPO was measured by radioimmunoassay in serum samples withdrawn every 30 min during altitude exposure and also in two subjects after termination of hypoxia (4,000 m). EPO levels during hypoxia were significantly elevated after 114 and 84 min (3,000 and 4,000 m), rising thereafter continuously for the period investigated. Mean values increased from 16.0 to 22.5 mU/ml (3,000 m) and from 16.7 to 28.0 mU/ml (4,000 m). This rise in EPO levels corresponds to 1.8-fold (3,000 m) and 3.0-fold (4,000 m) increases in the calculated production rate of the hormone. After termination of hypoxia, EPO levels continued to rise for approximately 1.5 h and after 3 h declined exponentially with an average half-life time of 5.2 h