Jacques Prioux

Diaphragm Movement Before and After Cholecystectomy: A Sonographic Study

Respiratory disorders after abdominal surgery are commonly explained by changes in diaphragmatic movement that are difficult to demonstrate and quantify. Our aim was thus to quantify these changes using a noninvasive method. We used M-mode sonography for the prospective study to measure diaphragmatic amplitude in 14 patients before and after cholecystectomy. During quiet breathing, the diaphragm inspiratory amplitude (DIA) was significantly decreased after surgery from 1.4 ± 0.2 cm to 1 ± 0.1 cm and from 1.6 ± 0.3 cm to 1.2 ± 0.3 cm in the Laparoscopic and Open Cholecystectomy groups, respectively. The total time cycle of diaphragmatic motion decreased significantly in the two groups. The DIA also decreased significantly during deep breathing after cholecystectomy from 6.0 ± 0.8 cm to 3.0 ± 1.8 cm and from 6.1 ± 1.3 cm to 3.1 ± 1.6 cm in the Laparoscopic and Open Cholecystectomy groups, respectively. The six patients who underwent spirometric examination showed, during quiet breathing, a significant decrease in DIA without change in tidal volume, i.e., 0.51 ± 0.08 L to 0.45 ± 0.08 L. We found a significant decrease in DIA after cholecystectomy and a significant interindividual correlation between DIA during deep inspiration and inspiratory capacity. Using M-mode sonography techniques, we were able to demonstrate changes in diaphragmatic mobility after laparoscopic or open cholecystectomy.

Effect of ageing on the ventilatory response and lactate kinetics during incremental exercise in man

Abstract We investigated the effects of age on breathing pattern, mouth occlusion pressure, the ratio of mouth occlusion pressure to mean inspiratory flow, and venous blood lactate kinetics during incremental exercise. Mouth occlusion pressure was used as an index of inspiratory neuromuscular activity, and its ratio to mean inspiratory flow was used as an index of the “effective impedance” of the respiratory system. Nine elderly male subjects [mean (SD) age: 68.1 (4.8) years] and nine young male subjects [mean (SD) age: 23.4 (1.3) years] performed an incremental exercise test on a bicycle ergometer. After a warm-up at 30 W, the power was increased by 30 W every 1.5 min until exhaustion. Our results showed that at maximal exercise, power output, breathing pattern, and respiratory exchange values, with the exception of tidal volume and the “effective impedance” of the respiratory system, were significantly higher in the young subjects. The power output and oxygen consumption values at the anaerobic threshold were also significantly higher in the young men. At the same power output, the elderly subjects showed significantly higher values for minute ventilation, respiratory equivalents for oxygen uptake and carbon dioxide output (CO2), mean inspiratory flow, occlusion pressure and lactate concentration than the young subjects. At the same CO2 below the anaerobic threshold (0.5, 0.75, 1.00 and 1.25 l · min−1), minute ventilation and lactate concentration were also significantly higher in the elderly subjects. We observed a significantly higher minute ventilation at CO2 values of 0.5, 0.75, 1.00 (P < 0.001) and 1.25 l · min−1 (P < 0.05) in the elderly men, and a significantly higher lactate concentration at CO2 values of 1.00 (P < 0.05) and 1.25 l · min−1 (P < 0.01). In conclusion, the ventilatory response in elderly subjects is elevated in comparison with that in young subjects, both below and above the anaerobic threshold. This study demonstrates for the first time that this ventilatory increase, both below and above the threshold, is partly due to an increased lactate concentration.

Effects of Playing Surface (hard and Clay Courts) on Heart Rate and Blood Lactate During Tennis Matches Played by High-level Players

Martin, C, Thevenet, D, Zouhal, H, Mornet, Y, Delès, R, Crestel, T, Ben Abderrahman, A, and Prioux, J. Effects of playing surface (hard and clay courts) on heart rate and blood lactate during tennis matches played by high level players. J Strength Cond Res 25(1): 163-170, 2011-The aim of this study was to compare tennis matches played on clay (CL) and resin (R) courts. Six matches were played (3 on CL courts and 3 on R courts) by 6 high-level players. Heart rate (HR) was monitored continuously while running time (4.66 m), and blood lactate concentration ([La]) were measured every 4 games. Mean duration of points and effective playing time (EPT) were measured for each match. Mean HR (154 ± 12 vs. 141 ± 9 b·min−1) and [La] values (5.7 ± 1.8 vs. 3.6 ± 1.2 mmol·L−1) were significantly higher on CL (p < 0.05). The [La] increased significantly during the match on CL court. Mean duration of rallies (8.5 ± 0.2 vs. 5.9 ± 0.5 seconds) and EPT (26.2 ± 1.9 vs. 19.5 ± 2.0%) were significantly longer (p < 0.05) on CL. Running time values in speed tests were not significantly different between CL and R. Running time performance was not significantly decreased during the match, whatever the playing surface. This study shows that the court surface influences the characteristics of the match and the players physiological responses. The court surface should be a key factor for consideration when coaches determine specific training programs for high-level tennis players.

Ventilation response to CO2 and exercise-induced hypoxaemia in master athletes

Abstract Exercise-induced hypoxaemia (EIH) in master athletes may be related to a diminished exercise hyper- pnoea. The aim of this study was to determine whether EIH is associated with a change in the sensitivity of the ventilation response to activation of the central chemoreceptors. The ventilation response to CO2 was measured in nine elderly untrained men (UT) [mean age 66.3 (SEM 3.1) years] and nine master athletes (MA) [mean age 62.7 (SEM 0.8) years] at rest, during moderate exercise (40% maximal oxygen uptake, V˙O2max), and during strenuous exercise (70% V˙O2max) using the rebreathing method. Our results showed that the ventilation response to CO2 did not differ with endurance training and/or exercise, that the threshold of the CO2 response (Th) increased with exercise (P < 0.001), that the increase in Th in MA was higher than in UT between rest and moderate exercise [ΔTh0–40: 8.55 (SEM 1.8) vs 3.06 (SEM 1.72) mmHg, P < 0.05], and that ΔTh0–40 and Th during moderate exercise were negatively correlated with arterial O2 saturation during maximal exercise (r = 0.50, P<0.05). We concluded therefore that exercise-induced hypoxaemia in master athletes may not be due to a lower ventilation response to CO2, but may be partly related to a greater increase in Th during moderate exercise.

Influence of recovery intensity on time spent at maximal oxygen uptake during an intermittent session in young, endurance-trained athletes

Abstract In this study, we examined the effects of three recovery intensities on time spent at a high percentage of maximal oxygen uptake (t90[Vdot]O2max) during a short intermittent session. Eight endurance-trained male adolescents (16 ± 1 years) performed four field tests until exhaustion: a graded test to determine maximal oxygen uptake ([Vdot]O2max; 57.4 ± 6.1 ml · min−1 · kg−1) and maximal aerobic velocity (17.9 ± 0.4 km · h−1), and three intermittent exercises consisting of repeat 30-s runs at 105% of maximal aerobic velocity alternating with 30 s active recovery at 50% (IE50), 67% (IE67), and 84% (IE84) of maximal aerobic velocity. In absolute values, mean t90[Vdot]O2max was not significantly different between IE50 and IE67, but both values were significantly longer compared with IE84. When expressed in relative values (as a percentage of time to exhaustion), mean t90[Vdot]O2max was significantly higher during IE67 than during IE50. Our results show that both 50% and 67% of maximal aerobic velocity of active recovery induced extensive solicitation of the cardiorespiratory system. Our results suggest that the choice of recovery intensity depends on the exercise objective.

Advanced classification of ambulatory activities using spectral density distances and heart rate

Abstract As motion sensors are getting light-weighted and low-priced, there is a growing appetite for the accelerometer-based approaches for efficiently monitoring human activities. This paper proposes an original feature selection approach based on the spectral distances between a given signal and an activity model. This new technique is evaluated and compared to existing techniques in literature. This study also investigates the improvement of classification performances brought by the heart rate (HR) data in addition to the accelerometer data. The experimental dataset is composed of both acceleration and HR recordings from eight volunteers performing five ambulation activities. Four wearable sensor units, including an ECG node are employed. The response of the system to three widely used classifiers, the K-nearest neighbors K-NN, the Naive Bayes NB and the decision Tree C4.5 is reported along with the classification rates. The results reached up to 99% of overall recognition accuracy and higher than 98% using a single-sensor acceleration data and the HR data. These results demonstrate that the spectral distances approach can be adopted to accurately classify activities and that the joint processing of acceleration signals together with the HR signals can increase the classification accuracy compared to the case when processing the acceleration signals alone.

Drafting improves 3000m running performance in elite athletes: Is it a placebo effect?

PURPOSE: The study was designed to determine the effect of drafting on running time, physiological response and rate of perceived exertion (RPE) during 3000m-track running. METHODS: Ten elite middle and long distance runners performed three track-running sessions. The first session determined maximal oxygen uptake (VO2max) and maximal aerobic speed (MAS) using a lightweight ambulatory respiratory gas exchange system (K4B2). The second and the third tests consisted of non-drafting 3000m running (3000mND) and 3000m running with drafting for the first 2000m (3000mD) performed on the track in a randomized counter-balanced order. RESULTS: Performance during the 3000m (553.59±22.15 s) was significantly slower (p<0.05) than during the 3000mD (544.74±18.72 s). Cardiorespiratory responses were not significantly different between the trials. However, blood lactate concentration was significantly higher (p<0.05) after the 3000mND (16.4±2.3mmol.L-1) than after the 3000mD (13.2±5.6mmol.L-1). Athletes perceived the 3000mND as more strenuous than the 3000mD (p<0.05) (RPE = 16.1±0.8 vs. 13.1±1.3). Results demonstrate that drafting has a significant effect on performance in highly trained runners. CONCLUSION: This effect could not be explained by a reduced energy expenditure or cardio-respiratory effort as a result of drafting. This raises the possibility that drafting may aid running performance by both physiological and non-physiological (i.e. psychological) effects.

Drafting's Improvement of 3000-m Running Performance in Elite Athletes: Is It a Placebo Effect?

PURPOSE To determine the effect of drafting on running time, physiological response, and rating of perceived exertion (RPE) during 3000-m track running. METHODS Ten elite middle- and long-distance runners performed 3 track-running sessions. The 1st session determined maximal oxygen uptake and maximal aerobic speed using a lightweight ambulatory respiratory gas-exchange system (K4B2). The 2nd and the 3rd tests consisted of nondrafting 3000-m running (3000-mND) and 3000-m running with drafting for the 1st 2000 m (3000-mD) performed on the track in a randomized counterbalanced order. RESULTS Performance during the 3000-mND (553.59±22.15 s) was significantly slower (P<.05) than during the 3000-mD (544.74±18.72 s). Cardiorespiratory responses were not significantly different between the trials. However, blood lactate concentration was significantly higher (P<.05) after the 3000-mND (16.4±2.3 mmol/L) than after the 3000-mD (13.2±5.6 mmol/L). Athletes perceived the 3000-mND as more strenuous than the 3000-mD (P<.05) (RPE=16.1±0.8 vs 13.1±1.3). Results demonstrate that drafting has a significant effect on performance in highly trained runners. CONCLUSION This effect could not be explained by a reduced energy expenditure or cardiorespiratory effort as a result of drafting. This raises the possibility that drafting may aid running performance by both physiological and nonphysiological (ie, psychological) effects.

Clinical Interest of Ambulatory Assessment of Physical Activity and Walking Capacity in Peripheral Artery Disease

The purpose of the present review was to provide, for the first time, a comprehensive analysis and synthesis of the available studies that highlighted the clinical interest of the ambulatory assessment of either physical activity (PA) or walking capacity in patients with lower extremity peripheral artery disease (PAD). We identified 96 related articles published up to March 2015 through a computer‐assisted search of the MEDLINE, EMBASE, and Web of Science databases. Ambulatory‐measured PA or related energy expenditure (EE) in PAD patients was performed in 87 of the 96 included studies. The main clinical interests of these measurements were (a) the assessment of PA/EE pattern; (b) the characterization of walking pattern; and (c) the control of training load during home‐based walking programs. Ambulatory‐measured walking capacity was performed in the remaining studies, using either Global Positioning System receivers or the Peripheral Arterial Disease Holter Control device. Highlighted clinical interests were (a) the assessment of community‐based walking capacity; (b) the use of new outcomes to characterize walking capacity, besides the conventional absolute claudication distance; and (c) the association with the patients self‐perception of walking capacity. This review also provides for the clinicians step‐by‐step recommendations to specifically assess PA or walking capacity in PAD patients.

Accuracy of a low-cost global positioning system receiver for estimating grade during outdoor walking

The aim of this study was to assess, for the first time, the accuracy of a low-cost global positioning system (GPS) receiver for estimating grade during outdoor walking. Thirty subjects completed outdoor walks (2.0, 3.5 and 5.0 km · h-1) in three randomized conditions: 1/level walking on a 0.0% grade; 2/graded (uphill and downhill) walking on a 3.4% grade; and 3/on a 10.4% grade. Subjects were equipped with a GPS receiver (DG100, GlobalSat Technology Corp., Taiwan; ~US