Cardiac Output and Performance during a Marathon Race in Middle-Aged Recreational Runners

Purpose. Despite the increasing popularity of marathon running, there are no data on the responses of stroke volume (SV) and cardiac output (CO) to exercise in this context. We sought to establish whether marathon performance is associated with the ability to sustain high fractional use of maximal SV and CO (i.e, cardiac endurance) and/or CO, per meter (i.e., cardiac cost). Methods. We measured the SV, heart rate (HR), CO, and running speed of 14 recreational runners in an incremental, maximal laboratory test and then during a real marathon race (mean performance: 3 hr 30 min ± 45 min). Results. Our data revealed that HR, SV and CO were all in a high but submaximal steady state during the marathon (87.0 ± 1.6%, 77.2 ± 2.6%, and 68.7 ± 2.8% of maximal values, respectively). Marathon performance was inversely correlated with an upward drift in the CO/speed ratio (mL of CO × m−1) (r = −0.65, P < 0.01) and positively correlated with the runner's ability to complete the race at a high percentage of the speed at maximal SV (r = 0.83, P < 0.0002). Conclusion. Our results showed that marathon performance is inversely correlated with cardiac cost and positively correlated with cardiac endurance. The CO response could be a benchmark for race performance in recreational marathon runners

Use of lumbar point for the estimation of potential and kinetic mechanical power in running

International audienceThe purpose of this study is to estimate the difference between potential and kinetic mechanical powers in running (Pke, Ppe) calculated from the centre of mass and one anatomic point of the body located on the lower part of the runner's back (the "lumbar point").Six runners carried out a treadmill run at constant velocity and are filmed individually with a video camera (25Hz). The 3D motion analysis system, ANIMAN3D, uses a numerical manikin (MAN3D) which compares a voluminal subject (the sportsman) directly to the manikin that possesses the same voluminal properties. This analysis system allows the trajectories of the centre of mass and the lumbar point to be calculated. Then, from these trajectories, potential and kinetic mechanical powers in running are calculated.The results show that the utilisation of the lumbar point rather than the centre of mass of the runner leads to a significant overestimation of Pke (p < 0.05) and a significant underestimation of Ppe (p < 0.05). However, in spite of these differences, the both methods of calculus of Pke and Ppe are well correlated (respectively r = 0.92; p ≤ 0.01 and r = 0.68; p ≤ 0.05).Taking into account that the trajectory of an anatomic point is experimentally easier to access than that of the centre of mass, this kind of point could be used to estimate the evolution of kinetic or potential energy variation in different cases. However, when the lumbar point rather than the centre of mass is used for the estimation of the mechanical energy produced in running, Pke could appear as a discriminating parameter, while it is not

Use of lumbar point for the estimation of potential and kinetic mechanical power in running

International audienceThe purpose of this study is to estimate the difference between potential and kinetic mechanical powers in running (Pke, Ppe) calculated from the centre of mass and one anatomic point of the body located on the lower part of the runner's back (the "lumbar point").Six runners carried out a treadmill run at constant velocity and are filmed individually with a video camera (25Hz). The 3D motion analysis system, ANIMAN3D, uses a numerical manikin (MAN3D) which compares a voluminal subject (the sportsman) directly to the manikin that possesses the same voluminal properties. This analysis system allows the trajectories of the centre of mass and the lumbar point to be calculated. Then, from these trajectories, potential and kinetic mechanical powers in running are calculated.The results show that the utilisation of the lumbar point rather than the centre of mass of the runner leads to a significant overestimation of Pke (p < 0.05) and a significant underestimation of Ppe (p < 0.05). However, in spite of these differences, the both methods of calculus of Pke and Ppe are well correlated (respectively r = 0.92; p ≤ 0.01 and r = 0.68; p ≤ 0.05).Taking into account that the trajectory of an anatomic point is experimentally easier to access than that of the centre of mass, this kind of point could be used to estimate the evolution of kinetic or potential energy variation in different cases. However, when the lumbar point rather than the centre of mass is used for the estimation of the mechanical energy produced in running, Pke could appear as a discriminating parameter, while it is not

Use of lumbar point for the estimation of potential and kinetic mechanical power in running

We begin our response by clarifying the concept of detection, and explaining why this is needed for initiating, but not for adjusting a movement. We present a simulation to illustrate this difference. Several commentators referred to studies with results that might seem in conflict with our proposal that movement adjustments have short latencies because there is no need to detect anything. In the last part of our response, we discuss how we interpret these studies as being in line with our proposal

Heart rate deflection point as a strategy to defend stroke volume during incremental exercise

Regarding the effectiveness of privatization, two schools of thought are distinguished: a school in favor of privatization in general and a school that judges the success of privatization to be dependent on the institutional context. This article discusses the arguments of both schools and presents a case study on the privatization processes that did take place in Kosovo. The Kosovo case is a critical case as Kosovo was a post-conflict country with a deplorable institutional setting at the time it initiated the privatization processes. If privatization was successful anyway, this would make for a strong argument in favor of privatization in general. The outcomes of the case study show, however, many unintended and negative effects of privatization in the Kosovo context. The conclusion, therefore, disputes the claim that privatization is beneficial in general, irrespective of the institutional setting. Instead, the article makes a plea for creating a favorable institutional setting before starting far-reaching transformations through large-scale privatization. The issues arising from this article are important for policy-makers and international missions considering implementing similar programs to other post-conflict countries

Physical and training characteristics of top-class marathon runners

Contains fulltext : mmubn000001_211285889.pdf (publisher's version ) (Open Access)Promotores : J. Jansen, F. Nagengast en J. Kuijpers147 p

Calculation of times to exhaustion at 100 and 120% maximal aerobic speed

Comparaison des réponses physiologiques lors d'épreuves de course sur tapis roulant à 100 et 120% de la vitesse aérobie maximale, poursuivies jusqu'à épuisement, chez 14 coureurs de quasi-élite. (La vitesse maximale aérobie est la vitesse minimale qui provoque la consommation maximale d'oxygène