Respiratory muscle strength is decreased after maximal incremental exercise in trained runners and cyclists

The respiratory muscle fatigue seems to be able to limit exercise performance and may influence the determination of maximal oxygen uptake (VO2max) or maximum aerobic work rate during maximal incremental test. The aim of this study was therefore to investigate whether maximal incremental exercise decreases respiratory muscle strength. We hypothesized that respiratory muscle strength (maximal pressure) will decrease after maximal incremental exercise to exhaustion. 36 runners and 23 cyclists completed a maximal incremental test on a treadmill or a cycle ergometer with continuous monitoring of expired gases. Maximal inspiratory (MIP) and expiratory (MEP) pressure measurements were taken at rest and post- exercise. At rest, the MIP and MEP were 140 +/- 25 and 172 +/- 27 in runners vs. 115 +/- 26 and 146 +/- 33 in cyclists (p 0.05), respectively. Our results suggest that respiratory muscle strength is decreased following maximal incremental exercise in trained runners and cyclists

Caractérisation fonctionnelle des muscles respiratoires : effets de l'entraînement et du désentraînement

The aim of thesis was on one hand to characterize the respiratory muscles during an incremental effort until exhaustion and on the other hand, to study the effects of specific inspiratory muscle training and detraining. We first confirmed the development of respiratory muscle fatigue during a maximal incremental exercise. Through recording of oxygenation at the 7th intercostal space, the second study showed reduced intercostal muscle deoxygenation and inspiratory muscle fatigue with a prior inspiratory exercise. Then, we showed that 5 weeks of specific inspiratory muscle training (IMT), whether at high or low intensity, reduces respiratory muscle fatigue induced by maximal incremental exercise. This reduction corroborates the parallel decrease observed in the intercostal muscle oxygen utilization and therefore in their metabolic demands in relation to their fatigability decrease (Study 3 and 4). This may reflect an increase in the oxygen supply of the locomotor muscles. These improvements were greater with high-resistance IMT. However, the IMT induced adaptations were lost after 10 weeks of detraining (Study 5). Nevertheless, reducing training frequency by up to two sessions per week while preserving the same training load was sufficient to maintain the already achieved adaptations. These results highlighted the respiratory muscle implication in the limitation of incremental effort until exhaustion and have contributed to a better understanding of the mechanisms underlying the improvement of performance after IMT particularly respiratory muscle oxygenation and fatigueL'objectif de cette thèse était d'une part la caractérisation des muscles respiratoires lors d'un effort incrémental jusqu'à l'épuisement et d'autre part, l'étude des effets de l'entraînement et de désentraînement spécifique des muscles inspiratoires. La première étude a confirmé le développement de la fatigue musculaire respiratoire lors d'un exercice incrémental maximal. À travers l'enregistrement de l'oxygénation au niveau du 7ème espace intercostal, la deuxième étude a montré la réduction de la désoxygénation des intercostaux et de la fatigue des muscles inspiratoires avec un exercice inspiratoire antérieur. Ensuite, nous avons montré que 5 semaines d'entraînement spécifique des muscles inspiratoires (IMT) que ce soit à haute ou à basse intensité réduit la fatigue musculaire respiratoire induite par l'exercice incrémental maximal. Cette réduction corrobore la diminution parallèle observée dans l'utilisation de l'O2 au niveau des muscles intercostaux et donc de leurs demandes métaboliques en lien avec la diminution de leur fatigabilité (Études 3 et 4). Ceci pourrait refléter une augmentation de l'apport d'oxygène au niveau des muscles locomoteurs. Ces améliorations étaient plus importantes avec l'IMT à haute résistance. Néanmoins, ces phénomènes adaptatifs gagnés à l'IMT étaient perdus après 10 semaines de désentraînement (Étude 5). Toutefois, la réduction de la fréquence d'IMT à deux séances par semaine tout en préservant la même charge résistive était suffisante pour maintenir les adaptations déjà obtenues. Les travaux de cette thèse ont donc mis en évidence l'implication des muscles respiratoires dans la limitation de l'effort incrémental jusqu'à l'épuisement et ont contribué à mieux comprendre les mécanismes explicatifs de l'amélioration de la performance après l'IMT et en particulier la fatigue et l'oxygénation musculaire respiratoir

Functional characterization of Respiratory muscles : effects of training and detraining

L'objectif de cette thèse était d'une part la caractérisation des muscles respiratoires lors d'un effort incrémental jusqu'à l'épuisement et d'autre part, l'étude des effets de l'entraînement et de désentraînement spécifique des muscles inspiratoires. La première étude a confirmé le développement de la fatigue musculaire respiratoire lors d'un exercice incrémental maximal. À travers l'enregistrement de l'oxygénation au niveau du 7ème espace intercostal, la deuxième étude a montré la réduction de la désoxygénation des intercostaux et de la fatigue des muscles inspiratoires avec un exercice inspiratoire antérieur. Ensuite, nous avons montré que 5 semaines d'entraînement spécifique des muscles inspiratoires (IMT) que ce soit à haute ou à basse intensité réduit la fatigue musculaire respiratoire induite par l'exercice incrémental maximal. Cette réduction corrobore la diminution parallèle observée dans l'utilisation de l'O2 au niveau des muscles intercostaux et donc de leurs demandes métaboliques en lien avec la diminution de leur fatigabilité (Études 3 et 4). Ceci pourrait refléter une augmentation de l'apport d'oxygène au niveau des muscles locomoteurs. Ces améliorations étaient plus importantes avec l'IMT à haute résistance. Néanmoins, ces phénomènes adaptatifs gagnés à l'IMT étaient perdus après 10 semaines de désentraînement (Étude 5). Toutefois, la réduction de la fréquence d'IMT à deux séances par semaine tout en préservant la même charge résistive était suffisante pour maintenir les adaptations déjà obtenues. Les travaux de cette thèse ont donc mis en évidence l'implication des muscles respiratoires dans la limitation de l'effort incrémental jusqu'à l'épuisement et ont contribué à mieux comprendre les mécanismes explicatifs de l'amélioration de la performance après l'IMT et en particulier la fatigue et l'oxygénation musculaire respiratoireThe aim of thesis was on one hand to characterize the respiratory muscles during an incremental effort until exhaustion and on the other hand, to study the effects of specific inspiratory muscle training and detraining. We first confirmed the development of respiratory muscle fatigue during a maximal incremental exercise. Through recording of oxygenation at the 7th intercostal space, the second study showed reduced intercostal muscle deoxygenation and inspiratory muscle fatigue with a prior inspiratory exercise. Then, we showed that 5 weeks of specific inspiratory muscle training (IMT), whether at high or low intensity, reduces respiratory muscle fatigue induced by maximal incremental exercise. This reduction corroborates the parallel decrease observed in the intercostal muscle oxygen utilization and therefore in their metabolic demands in relation to their fatigability decrease (Study 3 and 4). This may reflect an increase in the oxygen supply of the locomotor muscles. These improvements were greater with high-resistance IMT. However, the IMT induced adaptations were lost after 10 weeks of detraining (Study 5). Nevertheless, reducing training frequency by up to two sessions per week while preserving the same training load was sufficient to maintain the already achieved adaptations. These results highlighted the respiratory muscle implication in the limitation of incremental effort until exhaustion and have contributed to a better understanding of the mechanisms underlying the improvement of performance after IMT particularly respiratory muscle oxygenation and fatigu

Quadrotor UAV Dynamic Visual Servoing Based on Differential Flatness Theory

In this paper, we propose 2D dynamic visual servoing (Dynamic IBVS), where a quadrotor UAV tries to track a moving target using a single facing-down perspective camera. As an application, we propose the tracking of a car-type vehicle. In this case, data related to the altitude and the lateral angles have no importance for the visual system. Indeed, to perform the tracking, we only need to know the longitudinal displacements (along the x and y axes) and the orientation along the z-axis. However, those data are necessary for the quadrotor’s guidance problem. Thanks to the concept of differential flatness, we demonstrate that if we manage to extract the displacements according to the three axes and the orientation according to the yaw angle (the vertical axis) of the quadrotor, we can control all the other variables of the system. For this, we consider a camera equipped with a vertical stabilizer that keeps it in a vertical position during its movement (a gimbaled camera). Other specialized sensors measure information regarding altitude and lateral angles. In the case of classic 2D visual servoing, the elaboration of the kinematic torsor of the quadrotor in no way guarantees the physical realization of instructions, given that the quadrotor is an under-actuated system. Indeed, the setpoint has a dimension equal to six, while the quadrotor is controlled only by four inputs. In addition, the dynamics of a quadrotor are generally very fast, which requires a high-frequency control law. Furthermore, the complexity of the image processing stage can cause delays in motion control, which can lead to target loss. A new dynamic 2D visual servoing method (Dynamic IBVS) is proposed. This method makes it possible to generate in real time the necessary movements for the quadrotor in order to carry out the tracking of the target (vehicle) using a single point of this target as visual information. This point can represent the center of gravity of the target or any other part of it. A control by flatness has been proposed, which guarantees the controllability of the system and ensures the asymptotic convergence of the generated trajectory in the image plane. Numerical simulations are presented to show the effectiveness of the proposed control strategy

New Real-Time Impulse Noise Removal Method Applied to Chest X-ray Images

In this paper, we propose a new Modified Laplacian Vector Median Filter (MLVMF) for real-time denoising complex images corrupted by “salt and pepper” impulsive noise. The method consists of two rounds with three steps each: the first round starts with the identification of pixels that may be contaminated by noise using a Modified Laplacian Filter. Then, corrupted pixels pass a neighborhood-based validation test. Finally, the Vector Median Filter is used to replace noisy pixels. The MLVMF uses a 5 × 5 window to observe the intensity variations around each pixel of the image with a rotation step of π/8 while the classic Laplacian filters often use rotation steps of π/2 or π/4. We see better identification of noise-corrupted pixels thanks to this rotation step refinement. Despite this advantage, a high percentage of the impulsive noise may cause two or more corrupted pixels (with the same intensity) to collide, preventing the identification of noise-corrupted pixels. A second round is then necessary using a second set of filters, still based on the Laplacian operator, but allowing focusing only on the collision phenomenon. To validate our method, MLVMF is firstly tested on standard images, with a noise percentage varying from 3% to 30%. Obtained performances in terms of processing time, as well as image restoration quality through the PSNR (Peak Signal to Noise Ratio) and the NCD (Normalized Color Difference) metrics, are compared to the performances of VMF (Vector Median Filter), VMRHF (Vector Median-Rational Hybrid Filter), and MSMF (Modified Switching Median Filter). A second test is performed on several noisy chest x-ray images used in cardiovascular disease diagnosis as well as COVID-19 diagnosis. The proposed method shows a very good quality of restoration on this type of image, particularly when the percentage of noise is high. The MLVMF provides a high PSNR value of 5.5% and a low NCD value of 18.2%. Finally, an optimized Field-Programmable Gate Array (FPGA) design is proposed to implement the proposed method for real-time processing. The proposed hardware implementation allows an execution time equal to 9 ms per 256 × 256 color image