Mettre au point un test objectif simple et rapide permettant d’évaluer l’activité physique habitu... more Mettre au point un test objectif simple et rapide permettant d’évaluer l’activité physique habituelle d’adolescents en surpoids au cours d’une consultation médicale habituelle.Des adolescents ont été sélectionnés. Leur fréquence cardiaque (FC) et leur pression artérielle (PA) ont été mesurées au repos, debout, avant le début du test. Les sujets ont ensuite monté et descendu à la fréquence de 92 par minute, pendant 4 minutes, les 2 marches d’un marchepied médical. Leur FC a été suivie en continu. À la fin du test, la FC a été notée et la PA a été mesurée immédiatement. Les effets de l’activité physique habituelle et du sexe sur FC et PA ont été testés par ANOVA. Un questionnaire d’activités a été rempli par 43 des sujets pendant 7 jours et remis au médecin qui a complété les informations pendant la consultation et évalué l’activité physique habituelle.Cinquante-six adolescents des 2 sexes, âgés de 10 à 17 ans (31 sujets sédentaires [S] en surpoids et 25 sujets post-obèses actifs [A]) ont effectué le test sur marchepied. L’augmentation de la FC au cours du test était plus élevée chez les sujets S que chez les sujets A (66, 2 ± 2,3 vs 52,3 ± 2,5 bpm, p < 0,001). Les variations de la PA n’ont pas fourni d’information fiable sur l’activité physique habituelle des sujets. Le questionnaire d’activité a été rempli de façon satisfaisante par 72 % des sujets. Dans 95 % des cas, le classement des sujets en A ou S par le test sur marchepied était en accord avec le classement à partir du questionnaire.Le test sur marchepied permet une évaluation rapide et fiable de l’activité physique habituelle des enfants (à partir de l’âge de 6 ou 7 ans) dans 95 % des cas, au cours d’une consultation médicale habituelle (30 min), tandis que le questionnaire d’activités permet au praticien de vérifier les conclusions du test sur marchepied et de conseiller aux patients des activités physiques adaptées à leurs capacités physiques.To develop a simple, rapid, and unbiased test to assess usual physical activity in overweight adolescents during a routine medical consultation.Adolescents were selected. Their heart rate (HR) and blood pressure (BP) were measured at rest and when standing, before the beginning of the test. Subjects went up and down a 2-step apparatus during 4 minutes at a rate of 92 steps/min. HR was monitored. At the end of the test, the HR was noted and BP measured immediately. The effects of usual physical activity and gender on HR and BP were tested by ANOVA. In addition, an activity questionnaire was filled in by 43 subjects over 7 days and given to the doctor who completed the information during the visit, and assessed usual physical activity.56 adolescents of both sexes, aged 10-17 years (31 sedentary [S] overweight, and 25 active [A] post-obese subjects) underwent a step-test. The increase in HR during the test was significantly higher in S than in A subjects (66.2 ± 2.3 vs 52.3 ± 2.5 bpm, p < 0.001). However, the variations in BP did not supply reliable assessment of usual physical activity. The activity questionnaire had been filled in satisfactorily by 72% of subjects. In 95% of cases, the classification of subjects as S or A by the step-test agreed with the classification based on the questionnaire.The step-test provided the rapid and reliable assessment of usual physical activity of the children (from 6-7 years of age) in 95% of cases during a routine consultation (30 min), and the activity questionnaire enabled the doctor to check the conclusions of the step-test and recommend to the parents physical activities adapted to the physical capacities of their children.
This investigation aimed to compare the response of older adult and young men to bed-rest and sub... more This investigation aimed to compare the response of older adult and young men to bed-rest and subsequent rehabilitation. Sixteen older (OM: 55-65 years) and seven young men (YM: 18-30 years) were exposed to 14-day bed rest (BR) followed by 14-day rehabilitation (R). Quadriceps muscle volume (QVOL), force (QF) and explosive power (QP) of leg extensors, single fiber isometric force (Fo), peak aerobic power (VO2peak), gait stride length, and three metabolic parameters, Matsuda index of insulin sensitivity, postprandial lipid curve and homocysteine plasma level, were measured before and after BR and after R. Following BR, QVOL declined more in OM (-8.3%) than in YM (-5.7%, P=0.031), QF (-13.2%; P=0.001), QP (-12.3%; P=0.001) and gait stride length (-9.9%; P=0.002) declined only in OM. Fo significantly declined in both YM -32.0% and OM -16.4% without significant differences between groups. VO2peak declined more in OM (-15.3%) than in YM (-7.6%, P&amp;amp;amp;amp;amp;amp;amp;amp;lt;0.001). Instead, Matsuda index showed greater decline in YM than in OM (-46.0% vs. -19.8%, respectively; P=0.003), while increase in postprandial lipid curve (+47.2%; P=0.013) and homocysteine concentration (+26.3%; P=0.027) were observed only in YM. Importantly, after R, the recovery of several parameters, among them QVOL, QP and VO2peak, was not complete in OM, while Fo did not recover in both age groups. The results show that the impact of inactivity on muscle mass and function is greater in OM, while the metabolic alterations are greater in YM. Furthermore, these findings show that the recovery of pre-inactivity conditions is slower in OM.
International Journal of Sports Physiology and Performance, 2015
To investigate the effects of an uphill-marathon (43 km, 3063 m elevation gain) on running mechan... more To investigate the effects of an uphill-marathon (43 km, 3063 m elevation gain) on running mechanics and neuromuscular fatigue in lower limb muscles. Maximal mechanical power of lower limbs (MMP), temporal tensiomyography (TMG) parameters and muscle belly displacement (Dm) were determined in the vastus lateralis muscle before and after the competition in eighteen runners (age: 42.8±9.9 yr; body mass: 70.1±7.3 kg; maximal oxygen uptake: 55.5±7.5 mL·kg-1·min-1). Contact (tc) and aerial (ta) times, step frequency (f) and running velocity (v) were measured at 3,14,30 km and after the finish line (POST). Peak vertical ground reaction force (Fmax), vertical displacement of the centre of mass (Δz), leg length change (ΔL), vertical (kvert) and leg (kleg) stiffness were calculated. MMP was inversely related with race time (r:-0.56,p:0.016), tc (r:-0.61,p:0.008), Δz (r:-0.57,p:0.012) and directly related with Fmax (r:0.59,p:0.010), ta (r:0.48,p:0.040), kvert (r:0.51,p:0.027). In the fastest sub-group (n:9) the following parameters were lower in POST (p&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;0.05) than at km 3: ta (-14.1±17.8%), Fmax (-6.2±6.4%), kvert (-17.5±17.2%), kleg (-11.4±10.9%). The slowest sub-group (n:9) showed changes (p&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;0.05) at km 30 and POST in Fmax (-5.5±4.9% and -5.3±4.1%), ta (-20.5±16.2% and -21.5±14.4%), tc (+5.5±7.5% and +3.2±5.2%), kvert (-14.0±12.8% and -11.8±10.0%), kleg (-8.9±11.5 and -11.9±12%). TMG temporal-parameters decreased in all runners (-27.35±18.0%,p&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;0.001), while Dm increased (+24.0±35.0%,p:0.005), showing lower muscle stiffness and higher muscle sensibility to the electrical stimulus. Greater MMP was related with smaller changes in running biomechanics induced by fatigue. Thus, lower limb power training could improve running performance in uphill-marathons.
The prevalence of obesity in children has increased dramatically during the past decades, and req... more The prevalence of obesity in children has increased dramatically during the past decades, and requires efficient care. To determine changes in anthropometric parameters and basal metabolic rate (BMR) in obese adolescents during and after 2 types of weight-reduction programs. Twenty-six adolescents (group I, Z-score of BMI = 4.72) followed a 9-month-weight reduction program including a moderate energy restriction and regular physical activities in a specialized institution. In addition, 39 adolescents (group E, Z-score of BMI = 2.83) followed at home a 9-month-weight reduction program including medical and dietetic advices. Body composition (by impedancemetry) and BMR (by indirect calorimetry) were assessed before the beginning (M0), 4 months after (M4) and at the end (M9) of the programs, then 4 months (M13) and 16 month (M25) after the end of the weight-reduction programs. Twenty-two adolescents in group I and 20 adolescents in group E completed the study. At M0, age, body weight (BW), fat-free mass (FFM) and BMR of subjects of group I were higher (1.0 year, 36 %, 30 % and 23 %, respectively, P &lt; 0.001), than those of group E. Pubertal stage and percentage of fat mass (FM) were not significantly different between the 2 groups. At M9, adolescents of group I showed significant reductions in BW and FM (-19 and -37 %, respectively, P &lt; 0.001), but not significant differences in FFM. In addition, BMR decreased significantly between M0 and M4, both in absolute value (-6.7%, P &lt; 0.001) and after adjustment for FFM (-5.8%, P &lt; 0.001), and the difference was maintained until M9. Between M9 and M13, BW and Z-score of BMI were maintained in 12 adolescents, but increased (+9.7% and 14.8%, respectively, P &lt; 0.001) in 10 adolescents. However, BMR did not change significantly in all adolescents. Between M13 and M25, BW, FM, FFM and BMR increased significantly (+13%, +34%, +6% et +5%, respectively, P &lt; 0.001). During the 25 month period, adolescents of group E showed significant increases in BW, FFM and BMR (+8%, +14% and +10%, respectively, P &lt; 0.001), and maintained their Z-score and FM. The reduction in BMR during the weight-reduction program at the institution could contribute to body weight regain in the post-obese adolescents if they do not maintain the lifestyle habits taught during the weight-reduction period. In other respects, Z-score was stabilized in 51% of domiciled obese adolescents.
Professionals in charge of overweight and obese children and adolescents need a simple, reliable ... more Professionals in charge of overweight and obese children and adolescents need a simple, reliable and precise method for assessing body composition. To compare body composition as assessed by dual-energy X-ray absorptiometry (DXA), bioelectrical impedance analysis (BIA) and the skinfold thickness (SFT) method in overweight and obese adolescents, and to establish and validate new predictive equations of body composition from BIA measurements using DXA as standard method. Body composition was assessed in 143 obese adolescents (Z-score = 3.2 +/- 1.4) aged 12 to 17 years by DXA, BIA (RJL System, Analycor and Analycor XF models) and SFT (Siri and Slaughter&#39;s equations). New prediction equations of fat mass (FM) as assessed by DXA were computed from BIA measurements in a calibration group, and validated in an homologous group of subjects. Results. - The Bland-Altman test showed that compared to DXA, BIA underestimated FM by 2.8 +/- 2.0 kg and 2.3 +/- 2.1 kg using the RJL System and Analycor impedancemeter, respectively (P &lt; 0.001). With the Analycor XF model, FM was underestimated by 3.3 +/-2.6 kg in boys, and over-valued by 0.6 +/- 2.4 kg in girls. On the contrary, the predictive equation of Wabitsch et al. overvalued FM by 6.2 +/- 2.9 kg. The SFT method overvalued FM by 2.1 +/- 5.0 kg in boys and underestimated FM by 2.3 +/- 3.5 kg in girls using Slaughter et al. equation, while Siri&#39;s equation underestimated FM by 4.0 +/- 2.9 kg (P &lt; 0.001). The alternative to the DXA method to assess FM was BIA with new prediction equations including gender, body weight, height(2)/resistance and reactance. DXA, BIA and the SFT method were not directly interchangeable. The SFT method was inadequate to assess body composition in overweight and obese adolescents. BIA and new prediction equations could be an alternative to the DXA method in overweight and obese adolescents.
To develop a simple, rapid, and unbiased test to assess usual physical activity in overweight ado... more To develop a simple, rapid, and unbiased test to assess usual physical activity in overweight adolescents during a routine medical consultation. Adolescents were selected. Their heart rate (HR) and blood pressure (BP) were measured at rest and when standing, before the beginning of the test. Subjects went up and down a 2-step apparatus during 4 minutes at a rate of 92 steps/min. HR was monitored. At the end of the test, the HR was noted and BP measured immediately. The effects of usual physical activity and gender on HR and BP were tested by ANOVA. In addition, an activity questionnaire was filled in by 43 subjects over 7 days and given to the doctor who completed the information during the visit and assessed usual physical activity. 56 adolescents of both sexes, aged 10-17 years (31 sedentary [S] overweight, and 25 active [A] post-obese subjects) underwent a step-test. The increase in HR during the test was significantly higher in S than in A subjects (66.2 +/- 2.3 vs 52.3 +/- 2.5 bpm, p &amp;amp;amp;amp;amp;amp;lt; 0.001). However, the variations in BP did not supply reliable assessment of usual physical activity. The activity questionnaire had been filled in satisfactorily by 72% of subjects. In 95% of cases, the classification of subjects as S or A by the step-test agreed with the classification based on the questionnaire. The step-test provided the rapid and reliable assessment of usual physical activity of the children (from 6-7 years of age) in 95% of cases during a routine consultation (30 min), and the activity questionnaire enabled the doctor to check the conclusions of the step-test and recommend to the parents physical activities adapted to the physical capacities of their children.
The Journal of sports medicine and physical fitness, 2013
We assessed the subject's capacity to accelerate himself laterally in monopodalic support, a ... more We assessed the subject's capacity to accelerate himself laterally in monopodalic support, a crucial ability in several team sports, on 22 athletes, during series of 10 subsequent jumps, between two force platforms at predetermined distance. Vertical and horizontal accelerations of the Centre of Mass (CM), contact and flight times were measured by means of force platforms and the Optojump-System®. Individual mean horizontal and vertical powers and their sum (total power) ranged between 7 and 14.5 W/kg. "Push angle", i.e., the angle with the horizontal along which the vectorial sum of all forces is aligned, was calculated from the ratio between vertical and horizontal accelerations: it varied between 38.7 and 49.4 deg and was taken to express the subject technical ability. The horizontal acceleration of CM, indirectly estimated as a function of subject's mass, contact and flight times, was essentially equal to that obtained from force platforms data. Since the verti...
The Journal of sports medicine and physical fitness, 2010
To investigate exercise intensity, energy expenditure and energy balance of athletes during an ul... more To investigate exercise intensity, energy expenditure and energy balance of athletes during an ultraendurance event (UE) consisting in hiking, cycling and mountain climbing. Four athletes participated in this study. Maximal oxygen uptake (VO2max) and "VO2-heart rate" relationships during cycling and walking were determined by indirect calorimetry during two graded exercise tests. Body mass and body fat mass were measured before and after the UE. During the UE, heart rate (HR), diet intake, gastrointestinal disturbances and route characteristics were monitored. UE duration was 19 h29 min over a distance of 108 km, with 6768 meters of altitude difference. Body mass and percent of body fat mass tended to decrease after UE (-3.2% and -8.9%, respectively). During the locomotion phases, mean exercise intensity was 50.8±10.4% of VO2max and 65.8±7.6% of HRmax. Energy expenditure amounted to 51.0±3.4 MJ. Energy supplied from diet and body fat mass oxidation was 20.4±10.7 MJ and 17....
Presse médicale (Paris, France : 1983), Jan 23, 2004
To develop a simple, rapid, and unbiased test to assess usual physical activity in overweight ado... more To develop a simple, rapid, and unbiased test to assess usual physical activity in overweight adolescents during a routine medical consultation. Adolescents were selected. Their heart rate (HR) and blood pressure (BP) were measured at rest and when standing, before the beginning of the test. Subjects went up and down a 2-step apparatus during 4 minutes at a rate of 92 steps/min. HR was monitored. At the end of the test, the HR was noted and BP measured immediately. The effects of usual physical activity and gender on HR and BP were tested by ANOVA. In addition, an activity questionnaire was filled in by 43 subjects over 7 days and given to the doctor who completed the information during the visit and assessed usual physical activity. 56 adolescents of both sexes, aged 10-17 years (31 sedentary [S] overweight, and 25 active [A] post-obese subjects) underwent a step-test. The increase in HR during the test was significantly higher in S than in A subjects (66.2 +/- 2.3 vs 52.3 +/- 2.5 ...
The objective of the present study was to determine the accuracy of two foot-to-foot (FF) bioelec... more The objective of the present study was to determine the accuracy of two foot-to-foot (FF) bioelectrical impedance analysers (BIA) to assess body composition in overweight and obese adolescents, compared with dual-energy X-ray absorptiometry (DXA) and hand-to-foot (HF) BIA. Body composition was assessed in fifty-three overweight or obese adolescents (BMI 27.9 (SD 4.1) kg/m2; aged 13-16 years) by DXA (Hologic QDR-4500; Hologic Inc., Bedford, MA, USA) and BIA (HF (BIA 101, RJL System, Detroit, IL, USA) and FF (Body Fat Monitor Scale BF-625, Tanita Corporation of America Inc., Arlington Heights, IL, USA; Téfal Bodymaster Vision, Téfal, Rumilly, France)). Bland-Altman tests showed that, compared with DXA, FF-Tanita and FF-Téfal underestimated (P<0.05) fat mass (FM) less than HF-BIA (-1.7 (SD 3.1), -0.7 (SD 5.8) and -2.3 (SD 2.2) kg respectively, P<0.001). However, the limits of agreement between DXA and FF-Tanita or FF-Téfal were much greater than those obtained with HF-BIA (-7.7 a...
Information on activity patterns and the energy cost of activities is critically missing. We meas... more Information on activity patterns and the energy cost of activities is critically missing. We measured the energy cost of and time devoted to various activities in obese and nonobese adolescents. Daily energy expenditure (DEE) and its main components were determined in 27 obese and 50 nonobese adolescents aged 12-16 y by using whole-body calorimetry with the same activity program and the heart rate-recording method in free-living conditions. In whole-body calorimetry, energy expenditures (EEs) during sleep and sedentary activities were 18.9% and 21.5%, respectively, higher in obese subjects than in nonobese subjects (P < 0.001), but not significantly different after adjustment for fat-free mass (FFM). EEs during walking and DEEs were significantly higher in obese than in nonobese subjects, both absolutely (71% and 33%, respectively) and after adjustment for body weight or FFM (16% and 11%, respectively). In free-living conditions, EEs associated with physical activities did not di...
International Journal of Sports Physiology and Performance, 2014
Shuttle runs can be used to study the physiological responses in sports (such as basketball) char... more Shuttle runs can be used to study the physiological responses in sports (such as basketball) characterized by sprints (accelerations/ decelerations) and changes of direction. To determine the energy cost (C) of shuttle runs with different turning angles and over different distances (with different acceleration/deceleration patterns). Nine basketball players were asked to complete 6 intermittent tests over different distances (5, 10, 25 m) and with different changes of direction (180° at 5 and 25 m; 0°, 45°, 90°, and 180° at 10 m) at maximal speed (v ≈ 4.5 m/s), each composed by 10 shuttle runs of 10-s duration and 30-s recovery; during these runs oxygen uptake (VO(2)), blood lactate (Lab), and C were determined. For a given shuttle distance (10 m) no major differences where observed in VO(2) (~33 mL · min⁻¹ · kg⁻¹), Lab (~3.75 mM), and C (~21.2 J · m⁻¹ · kg⁻¹) when the shuttle runs were performed with different turning angles. For a given turning angle (180°), VO(2) and Lab were found to increase with the distance covered (VO(2) from 26 to 35 mL · min⁻¹ · kg⁻¹; Lab from 0.7 to 7.6 mM) while C was found to decrease with it (from 29.9 to 10.6 J · m⁻¹ · kg⁻¹); the relationship between C and d (m) is well described by C = 92.99 × d0.656, R2 = .971. The metabolic demands of shuttle tests run at maximal speeds can be estimated based on the running distance, while the turning angle plays a minor role in determining C.
Mettre au point un test objectif simple et rapide permettant d’évaluer l’activité physique habitu... more Mettre au point un test objectif simple et rapide permettant d’évaluer l’activité physique habituelle d’adolescents en surpoids au cours d’une consultation médicale habituelle.Des adolescents ont été sélectionnés. Leur fréquence cardiaque (FC) et leur pression artérielle (PA) ont été mesurées au repos, debout, avant le début du test. Les sujets ont ensuite monté et descendu à la fréquence de 92 par minute, pendant 4 minutes, les 2 marches d’un marchepied médical. Leur FC a été suivie en continu. À la fin du test, la FC a été notée et la PA a été mesurée immédiatement. Les effets de l’activité physique habituelle et du sexe sur FC et PA ont été testés par ANOVA. Un questionnaire d’activités a été rempli par 43 des sujets pendant 7 jours et remis au médecin qui a complété les informations pendant la consultation et évalué l’activité physique habituelle.Cinquante-six adolescents des 2 sexes, âgés de 10 à 17 ans (31 sujets sédentaires [S] en surpoids et 25 sujets post-obèses actifs [A]) ont effectué le test sur marchepied. L’augmentation de la FC au cours du test était plus élevée chez les sujets S que chez les sujets A (66, 2 ± 2,3 vs 52,3 ± 2,5 bpm, p < 0,001). Les variations de la PA n’ont pas fourni d’information fiable sur l’activité physique habituelle des sujets. Le questionnaire d’activité a été rempli de façon satisfaisante par 72 % des sujets. Dans 95 % des cas, le classement des sujets en A ou S par le test sur marchepied était en accord avec le classement à partir du questionnaire.Le test sur marchepied permet une évaluation rapide et fiable de l’activité physique habituelle des enfants (à partir de l’âge de 6 ou 7 ans) dans 95 % des cas, au cours d’une consultation médicale habituelle (30 min), tandis que le questionnaire d’activités permet au praticien de vérifier les conclusions du test sur marchepied et de conseiller aux patients des activités physiques adaptées à leurs capacités physiques.To develop a simple, rapid, and unbiased test to assess usual physical activity in overweight adolescents during a routine medical consultation.Adolescents were selected. Their heart rate (HR) and blood pressure (BP) were measured at rest and when standing, before the beginning of the test. Subjects went up and down a 2-step apparatus during 4 minutes at a rate of 92 steps/min. HR was monitored. At the end of the test, the HR was noted and BP measured immediately. The effects of usual physical activity and gender on HR and BP were tested by ANOVA. In addition, an activity questionnaire was filled in by 43 subjects over 7 days and given to the doctor who completed the information during the visit, and assessed usual physical activity.56 adolescents of both sexes, aged 10-17 years (31 sedentary [S] overweight, and 25 active [A] post-obese subjects) underwent a step-test. The increase in HR during the test was significantly higher in S than in A subjects (66.2 ± 2.3 vs 52.3 ± 2.5 bpm, p < 0.001). However, the variations in BP did not supply reliable assessment of usual physical activity. The activity questionnaire had been filled in satisfactorily by 72% of subjects. In 95% of cases, the classification of subjects as S or A by the step-test agreed with the classification based on the questionnaire.The step-test provided the rapid and reliable assessment of usual physical activity of the children (from 6-7 years of age) in 95% of cases during a routine consultation (30 min), and the activity questionnaire enabled the doctor to check the conclusions of the step-test and recommend to the parents physical activities adapted to the physical capacities of their children.
This investigation aimed to compare the response of older adult and young men to bed-rest and sub... more This investigation aimed to compare the response of older adult and young men to bed-rest and subsequent rehabilitation. Sixteen older (OM: 55-65 years) and seven young men (YM: 18-30 years) were exposed to 14-day bed rest (BR) followed by 14-day rehabilitation (R). Quadriceps muscle volume (QVOL), force (QF) and explosive power (QP) of leg extensors, single fiber isometric force (Fo), peak aerobic power (VO2peak), gait stride length, and three metabolic parameters, Matsuda index of insulin sensitivity, postprandial lipid curve and homocysteine plasma level, were measured before and after BR and after R. Following BR, QVOL declined more in OM (-8.3%) than in YM (-5.7%, P=0.031), QF (-13.2%; P=0.001), QP (-12.3%; P=0.001) and gait stride length (-9.9%; P=0.002) declined only in OM. Fo significantly declined in both YM -32.0% and OM -16.4% without significant differences between groups. VO2peak declined more in OM (-15.3%) than in YM (-7.6%, P&amp;amp;amp;amp;amp;amp;amp;amp;lt;0.001). Instead, Matsuda index showed greater decline in YM than in OM (-46.0% vs. -19.8%, respectively; P=0.003), while increase in postprandial lipid curve (+47.2%; P=0.013) and homocysteine concentration (+26.3%; P=0.027) were observed only in YM. Importantly, after R, the recovery of several parameters, among them QVOL, QP and VO2peak, was not complete in OM, while Fo did not recover in both age groups. The results show that the impact of inactivity on muscle mass and function is greater in OM, while the metabolic alterations are greater in YM. Furthermore, these findings show that the recovery of pre-inactivity conditions is slower in OM.
International Journal of Sports Physiology and Performance, 2015
To investigate the effects of an uphill-marathon (43 km, 3063 m elevation gain) on running mechan... more To investigate the effects of an uphill-marathon (43 km, 3063 m elevation gain) on running mechanics and neuromuscular fatigue in lower limb muscles. Maximal mechanical power of lower limbs (MMP), temporal tensiomyography (TMG) parameters and muscle belly displacement (Dm) were determined in the vastus lateralis muscle before and after the competition in eighteen runners (age: 42.8±9.9 yr; body mass: 70.1±7.3 kg; maximal oxygen uptake: 55.5±7.5 mL·kg-1·min-1). Contact (tc) and aerial (ta) times, step frequency (f) and running velocity (v) were measured at 3,14,30 km and after the finish line (POST). Peak vertical ground reaction force (Fmax), vertical displacement of the centre of mass (Δz), leg length change (ΔL), vertical (kvert) and leg (kleg) stiffness were calculated. MMP was inversely related with race time (r:-0.56,p:0.016), tc (r:-0.61,p:0.008), Δz (r:-0.57,p:0.012) and directly related with Fmax (r:0.59,p:0.010), ta (r:0.48,p:0.040), kvert (r:0.51,p:0.027). In the fastest sub-group (n:9) the following parameters were lower in POST (p&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;0.05) than at km 3: ta (-14.1±17.8%), Fmax (-6.2±6.4%), kvert (-17.5±17.2%), kleg (-11.4±10.9%). The slowest sub-group (n:9) showed changes (p&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;0.05) at km 30 and POST in Fmax (-5.5±4.9% and -5.3±4.1%), ta (-20.5±16.2% and -21.5±14.4%), tc (+5.5±7.5% and +3.2±5.2%), kvert (-14.0±12.8% and -11.8±10.0%), kleg (-8.9±11.5 and -11.9±12%). TMG temporal-parameters decreased in all runners (-27.35±18.0%,p&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;0.001), while Dm increased (+24.0±35.0%,p:0.005), showing lower muscle stiffness and higher muscle sensibility to the electrical stimulus. Greater MMP was related with smaller changes in running biomechanics induced by fatigue. Thus, lower limb power training could improve running performance in uphill-marathons.
The prevalence of obesity in children has increased dramatically during the past decades, and req... more The prevalence of obesity in children has increased dramatically during the past decades, and requires efficient care. To determine changes in anthropometric parameters and basal metabolic rate (BMR) in obese adolescents during and after 2 types of weight-reduction programs. Twenty-six adolescents (group I, Z-score of BMI = 4.72) followed a 9-month-weight reduction program including a moderate energy restriction and regular physical activities in a specialized institution. In addition, 39 adolescents (group E, Z-score of BMI = 2.83) followed at home a 9-month-weight reduction program including medical and dietetic advices. Body composition (by impedancemetry) and BMR (by indirect calorimetry) were assessed before the beginning (M0), 4 months after (M4) and at the end (M9) of the programs, then 4 months (M13) and 16 month (M25) after the end of the weight-reduction programs. Twenty-two adolescents in group I and 20 adolescents in group E completed the study. At M0, age, body weight (BW), fat-free mass (FFM) and BMR of subjects of group I were higher (1.0 year, 36 %, 30 % and 23 %, respectively, P &lt; 0.001), than those of group E. Pubertal stage and percentage of fat mass (FM) were not significantly different between the 2 groups. At M9, adolescents of group I showed significant reductions in BW and FM (-19 and -37 %, respectively, P &lt; 0.001), but not significant differences in FFM. In addition, BMR decreased significantly between M0 and M4, both in absolute value (-6.7%, P &lt; 0.001) and after adjustment for FFM (-5.8%, P &lt; 0.001), and the difference was maintained until M9. Between M9 and M13, BW and Z-score of BMI were maintained in 12 adolescents, but increased (+9.7% and 14.8%, respectively, P &lt; 0.001) in 10 adolescents. However, BMR did not change significantly in all adolescents. Between M13 and M25, BW, FM, FFM and BMR increased significantly (+13%, +34%, +6% et +5%, respectively, P &lt; 0.001). During the 25 month period, adolescents of group E showed significant increases in BW, FFM and BMR (+8%, +14% and +10%, respectively, P &lt; 0.001), and maintained their Z-score and FM. The reduction in BMR during the weight-reduction program at the institution could contribute to body weight regain in the post-obese adolescents if they do not maintain the lifestyle habits taught during the weight-reduction period. In other respects, Z-score was stabilized in 51% of domiciled obese adolescents.
Professionals in charge of overweight and obese children and adolescents need a simple, reliable ... more Professionals in charge of overweight and obese children and adolescents need a simple, reliable and precise method for assessing body composition. To compare body composition as assessed by dual-energy X-ray absorptiometry (DXA), bioelectrical impedance analysis (BIA) and the skinfold thickness (SFT) method in overweight and obese adolescents, and to establish and validate new predictive equations of body composition from BIA measurements using DXA as standard method. Body composition was assessed in 143 obese adolescents (Z-score = 3.2 +/- 1.4) aged 12 to 17 years by DXA, BIA (RJL System, Analycor and Analycor XF models) and SFT (Siri and Slaughter&#39;s equations). New prediction equations of fat mass (FM) as assessed by DXA were computed from BIA measurements in a calibration group, and validated in an homologous group of subjects. Results. - The Bland-Altman test showed that compared to DXA, BIA underestimated FM by 2.8 +/- 2.0 kg and 2.3 +/- 2.1 kg using the RJL System and Analycor impedancemeter, respectively (P &lt; 0.001). With the Analycor XF model, FM was underestimated by 3.3 +/-2.6 kg in boys, and over-valued by 0.6 +/- 2.4 kg in girls. On the contrary, the predictive equation of Wabitsch et al. overvalued FM by 6.2 +/- 2.9 kg. The SFT method overvalued FM by 2.1 +/- 5.0 kg in boys and underestimated FM by 2.3 +/- 3.5 kg in girls using Slaughter et al. equation, while Siri&#39;s equation underestimated FM by 4.0 +/- 2.9 kg (P &lt; 0.001). The alternative to the DXA method to assess FM was BIA with new prediction equations including gender, body weight, height(2)/resistance and reactance. DXA, BIA and the SFT method were not directly interchangeable. The SFT method was inadequate to assess body composition in overweight and obese adolescents. BIA and new prediction equations could be an alternative to the DXA method in overweight and obese adolescents.
To develop a simple, rapid, and unbiased test to assess usual physical activity in overweight ado... more To develop a simple, rapid, and unbiased test to assess usual physical activity in overweight adolescents during a routine medical consultation. Adolescents were selected. Their heart rate (HR) and blood pressure (BP) were measured at rest and when standing, before the beginning of the test. Subjects went up and down a 2-step apparatus during 4 minutes at a rate of 92 steps/min. HR was monitored. At the end of the test, the HR was noted and BP measured immediately. The effects of usual physical activity and gender on HR and BP were tested by ANOVA. In addition, an activity questionnaire was filled in by 43 subjects over 7 days and given to the doctor who completed the information during the visit and assessed usual physical activity. 56 adolescents of both sexes, aged 10-17 years (31 sedentary [S] overweight, and 25 active [A] post-obese subjects) underwent a step-test. The increase in HR during the test was significantly higher in S than in A subjects (66.2 +/- 2.3 vs 52.3 +/- 2.5 bpm, p &amp;amp;amp;amp;amp;amp;lt; 0.001). However, the variations in BP did not supply reliable assessment of usual physical activity. The activity questionnaire had been filled in satisfactorily by 72% of subjects. In 95% of cases, the classification of subjects as S or A by the step-test agreed with the classification based on the questionnaire. The step-test provided the rapid and reliable assessment of usual physical activity of the children (from 6-7 years of age) in 95% of cases during a routine consultation (30 min), and the activity questionnaire enabled the doctor to check the conclusions of the step-test and recommend to the parents physical activities adapted to the physical capacities of their children.
The Journal of sports medicine and physical fitness, 2013
We assessed the subject's capacity to accelerate himself laterally in monopodalic support, a ... more We assessed the subject's capacity to accelerate himself laterally in monopodalic support, a crucial ability in several team sports, on 22 athletes, during series of 10 subsequent jumps, between two force platforms at predetermined distance. Vertical and horizontal accelerations of the Centre of Mass (CM), contact and flight times were measured by means of force platforms and the Optojump-System®. Individual mean horizontal and vertical powers and their sum (total power) ranged between 7 and 14.5 W/kg. "Push angle", i.e., the angle with the horizontal along which the vectorial sum of all forces is aligned, was calculated from the ratio between vertical and horizontal accelerations: it varied between 38.7 and 49.4 deg and was taken to express the subject technical ability. The horizontal acceleration of CM, indirectly estimated as a function of subject's mass, contact and flight times, was essentially equal to that obtained from force platforms data. Since the verti...
The Journal of sports medicine and physical fitness, 2010
To investigate exercise intensity, energy expenditure and energy balance of athletes during an ul... more To investigate exercise intensity, energy expenditure and energy balance of athletes during an ultraendurance event (UE) consisting in hiking, cycling and mountain climbing. Four athletes participated in this study. Maximal oxygen uptake (VO2max) and "VO2-heart rate" relationships during cycling and walking were determined by indirect calorimetry during two graded exercise tests. Body mass and body fat mass were measured before and after the UE. During the UE, heart rate (HR), diet intake, gastrointestinal disturbances and route characteristics were monitored. UE duration was 19 h29 min over a distance of 108 km, with 6768 meters of altitude difference. Body mass and percent of body fat mass tended to decrease after UE (-3.2% and -8.9%, respectively). During the locomotion phases, mean exercise intensity was 50.8±10.4% of VO2max and 65.8±7.6% of HRmax. Energy expenditure amounted to 51.0±3.4 MJ. Energy supplied from diet and body fat mass oxidation was 20.4±10.7 MJ and 17....
Presse médicale (Paris, France : 1983), Jan 23, 2004
To develop a simple, rapid, and unbiased test to assess usual physical activity in overweight ado... more To develop a simple, rapid, and unbiased test to assess usual physical activity in overweight adolescents during a routine medical consultation. Adolescents were selected. Their heart rate (HR) and blood pressure (BP) were measured at rest and when standing, before the beginning of the test. Subjects went up and down a 2-step apparatus during 4 minutes at a rate of 92 steps/min. HR was monitored. At the end of the test, the HR was noted and BP measured immediately. The effects of usual physical activity and gender on HR and BP were tested by ANOVA. In addition, an activity questionnaire was filled in by 43 subjects over 7 days and given to the doctor who completed the information during the visit and assessed usual physical activity. 56 adolescents of both sexes, aged 10-17 years (31 sedentary [S] overweight, and 25 active [A] post-obese subjects) underwent a step-test. The increase in HR during the test was significantly higher in S than in A subjects (66.2 +/- 2.3 vs 52.3 +/- 2.5 ...
The objective of the present study was to determine the accuracy of two foot-to-foot (FF) bioelec... more The objective of the present study was to determine the accuracy of two foot-to-foot (FF) bioelectrical impedance analysers (BIA) to assess body composition in overweight and obese adolescents, compared with dual-energy X-ray absorptiometry (DXA) and hand-to-foot (HF) BIA. Body composition was assessed in fifty-three overweight or obese adolescents (BMI 27.9 (SD 4.1) kg/m2; aged 13-16 years) by DXA (Hologic QDR-4500; Hologic Inc., Bedford, MA, USA) and BIA (HF (BIA 101, RJL System, Detroit, IL, USA) and FF (Body Fat Monitor Scale BF-625, Tanita Corporation of America Inc., Arlington Heights, IL, USA; Téfal Bodymaster Vision, Téfal, Rumilly, France)). Bland-Altman tests showed that, compared with DXA, FF-Tanita and FF-Téfal underestimated (P<0.05) fat mass (FM) less than HF-BIA (-1.7 (SD 3.1), -0.7 (SD 5.8) and -2.3 (SD 2.2) kg respectively, P<0.001). However, the limits of agreement between DXA and FF-Tanita or FF-Téfal were much greater than those obtained with HF-BIA (-7.7 a...
Information on activity patterns and the energy cost of activities is critically missing. We meas... more Information on activity patterns and the energy cost of activities is critically missing. We measured the energy cost of and time devoted to various activities in obese and nonobese adolescents. Daily energy expenditure (DEE) and its main components were determined in 27 obese and 50 nonobese adolescents aged 12-16 y by using whole-body calorimetry with the same activity program and the heart rate-recording method in free-living conditions. In whole-body calorimetry, energy expenditures (EEs) during sleep and sedentary activities were 18.9% and 21.5%, respectively, higher in obese subjects than in nonobese subjects (P < 0.001), but not significantly different after adjustment for fat-free mass (FFM). EEs during walking and DEEs were significantly higher in obese than in nonobese subjects, both absolutely (71% and 33%, respectively) and after adjustment for body weight or FFM (16% and 11%, respectively). In free-living conditions, EEs associated with physical activities did not di...
International Journal of Sports Physiology and Performance, 2014
Shuttle runs can be used to study the physiological responses in sports (such as basketball) char... more Shuttle runs can be used to study the physiological responses in sports (such as basketball) characterized by sprints (accelerations/ decelerations) and changes of direction. To determine the energy cost (C) of shuttle runs with different turning angles and over different distances (with different acceleration/deceleration patterns). Nine basketball players were asked to complete 6 intermittent tests over different distances (5, 10, 25 m) and with different changes of direction (180° at 5 and 25 m; 0°, 45°, 90°, and 180° at 10 m) at maximal speed (v ≈ 4.5 m/s), each composed by 10 shuttle runs of 10-s duration and 30-s recovery; during these runs oxygen uptake (VO(2)), blood lactate (Lab), and C were determined. For a given shuttle distance (10 m) no major differences where observed in VO(2) (~33 mL · min⁻¹ · kg⁻¹), Lab (~3.75 mM), and C (~21.2 J · m⁻¹ · kg⁻¹) when the shuttle runs were performed with different turning angles. For a given turning angle (180°), VO(2) and Lab were found to increase with the distance covered (VO(2) from 26 to 35 mL · min⁻¹ · kg⁻¹; Lab from 0.7 to 7.6 mM) while C was found to decrease with it (from 29.9 to 10.6 J · m⁻¹ · kg⁻¹); the relationship between C and d (m) is well described by C = 92.99 × d0.656, R2 = .971. The metabolic demands of shuttle tests run at maximal speeds can be estimated based on the running distance, while the turning angle plays a minor role in determining C.
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Papers by Stefano Lazzer