Impairment of lung volume perception and breathing control in hypermobile Ehlers-Danlos syndrome.

Breathing difficulties and exertional dyspnea are frequently reported in hypermobile Ehlers-Danlos syndrome (hEDS); however, they are not clearly explained. An impaired proprioception or the addition of a cognitive task could influence ventilatory control. How can the perception of lung volume be measured? Is lung volume perception impaired in hEDS patients? Is the breathing control impaired during a cognitive task in hEDS patients? A device was developed to assess the accuracy of lung volume perception in patients with hEDS and matched control subjects. In the second step, ventilation was recorded in both groups with and without a cognitive task. Two groups of 19 subjects were included. The accuracy of lung volume perception was significantly (P < 0.01) lower at 30% of inspired vital capacity in patients with hEDS in comparison to the control group, and they showed erratic ventilation (based on spatial and temporal criteria) when performing a cognitive task. These data support the influence of the proprioceptive deficit on ventilatory control in hEDS patients. These elements may help to understand the respiratory manifestations found in hEDS. Future research should focus on this relationship between lung volume perception and ventilation, and could contribute to our understanding of other pathologies or exercise physiology.Trial registration number: ClinicalTrials.gov, NCT05000151.

Middle-term effects of education programme in chronic low back pain patients to an adherence to physical activity: A randomized controlled trial.

OBJECTIVE: This study was to measure the impact of an education programme in Chronic Low Back Pain (CLBP) patients on their changing behaviour; particularly on the resumption or maintenance of physical activity (PA) at three and six months after care. METHODS: A two-group, randomised controlled clinical trial was conducted on 68 patients as the control group (CG) and 68 as the experimental group (EG). All patients benefited from a four-week multidisciplinary programme, with an educative programme for the EG. The dropouts of patients during the follow-up period and the PA level were measured at three and six months after the end of care. RESULTS: At 3-months, the EG presented a significant higher level of physical activity (91% of EG versus 77% of CG, p < 0.001) and at six months, this group presented a lower dropout rate than CG (60% of EG versus 73% of CG, p = 0.017). CONCLUSION: The educative programme, added to a multidisciplinary care plan, can improve adherence to the care programme and the continuum of PA. PRACTICE IMPLICATIONS: Add an educative programme focused on motivation, physical activity, stress management and daily activities seems necessary to accompany CLBP patient towards the maintenance of a regular PA.

Effects of a Physical Activity Program that Incorporates Exercises Targeting Balance, Strength, and Proprioception on Cognitive Functions and Physical Performance in Old Adults with Mild Cognitive Impairment.

BACKGROUND: Aging often leads to cognitive function decline, sensory structure deterioration, and musculoskeletal system weakening. This impacts postural control during static and dynamic activities like walking, increasing the fall risk among the elderly. Older adults with mild cognitive impairment (MCI) face an elevated fall risk and cognitive decline, magnifying the public health concern. OBJECTIVE: This study aimed to explore solutions by investigating the effects of a multi-component physical activity program on cognitive and motor functions in MCI patients. METHODS: Twenty-three participants were enrolled in the study and assigned into two groups: an intervention group (n = 13; age = 85.7±5.5 years) and a control group (n = 9; age = 85±6.7 years). The study spanned two months, with participants engaging in three 60-minute weekly physical exercise sessions. The intervention focused on improving proprioception, muscle strength, and balance. RESULTS: Results demonstrated significant enhancements in physical performance, fall risk reduction, and balance (p < 0.05). Various tests, including the timed up and go test, Unipedal Stance test, Tinetti test, Short Physical Performance Battery, and 6-minute walking test, indicated these improvements. Cognitive function was evaluated with the Mini-Mental State Examination, revealing non-significant progress (p > 0.05). Predictive models for outcomes were developed using linear regression analysis during the follow-up stage. CONCLUSIONS: This study underscores the effectiveness of a multi-component physical activity program encompassing balance, proprioception, and muscle-strengthening exercises as a non-pharmaceutical approach in improving balance skills and playing a key role in mitigating the risk of falls among old adults with MCI.

Multiple Sustainable Benefits of a Rehabilitation Program in Therapeutic Management of Hypermobile Ehlers-Danlos Syndrome: A Prospective and Controlled Study at Short- and Medium-Term.

OBJECTIVE: To evaluate the effects of a 9-week rehabilitation program (RP) for patients with hypermobile Ehlers-Danlos syndrome (hEDS) in the short- and medium-term. DESIGN: Nonrandomized controlled trial with 6 months follow-up. SETTING: Outpatient rehabilitation program. PARTICIPANTS: A referred sample of 36 hEDS patients were assessed for eligibility (N=36), 25 were included, 22 completed the RP and 19 completed the follow-up. INTERVENTIONS: A 9 -week control period without intervention followed by a 9-week RP. MAIN OUTCOME MEASURE: Functional exercise capacity was used as a primary outcome measure. Balance, kinesiophobia, fatigue, pain, quality of life, anxiety, depression, and hyperventilation were measured as secondary outcomes. RESULTS: No significant change was observed during the 9-week control period before the RP. There was a significant improvement immediately after the RP for the functional exercise capacity, balance with eyes closed, fatigue, and quality of life (P<.05). Even more improvements were found 6 weeks after the end of the RP, and there was still an improvement after 6 months in functional exercise capacity, kinesiophobia, depression, hyperventilation, and some components of the quality of life. CONCLUSION: This study supports the effectiveness of an RP as a useful management tool for hEDS patients.

Description of supportive care and feasibility of physical exercise program to improve quality of life in advanced melanoma patients.

Physical activity is the first-line treatment of cancer-related fatigue. It has shown benefits on patient's quality of life (QoL) when practiced during and after treatment. New treatments have drastically changed the prognosis of melanoma. Still, few data are available about research program of supportive care in advanced melanoma. The primary outcome was to assess the feasibility of setting up a prospective study evaluating the benefits of Adapted Physical Activity (APA) on the QoL of patients with advanced melanoma. Feasibility was defined with a combination of five criteria including completion of questionnaire, recruitment, participant retention, patient adhesion to supportive care, and absence of adverse event. Between September 2019 and March 2021, 271 melanoma patients were questioned. Around 60% of stage IV melanoma patients were interested in support care. Patient retention at 3 months was sufficient. Only one patient could not be evaluated after 3 months of enrolment because of deterioration of the general state. Adhesion to exercise and sessions was good. Supervised APA program appeared to be safe and well tolerated as no adverse events or discontinuations were reported. Setting up a prospective research program evaluating the benefits of physical activity in advanced melanoma patients seems feasible. With melanoma becoming a chronic disease, supportive care may reduce fatigue, improve QoL and help maintain a healthy lifestyle. Data supporting its benefits on this survivor population are needed.

Oxygen supplementation to limit hypoxia-induced muscle atrophy in C2C12 myotubes: comparison with amino acid supplement and electrical stimulation.

In skeletal muscle, chronic oxygen depletion induces a disturbance leading to muscle atrophy. Mechanical stress (physical exercise) and nutritional supplement therapy are commonly used against loss of muscle mass and undernutrition in hypoxia, while oxygenation therapy is preferentially used to counteract muscle fatigue and exercise intolerance. However, the impact of oxygenation on skeletal muscle cells remains poorly understood, in particular on signalling pathways regulating protein balance. Thus, we investigated the effects of each separated treatment (mechanical stress, nutritional supplementation and oxygenation therapy) on intracellular pathways involved in protein synthesis and degradation that are imbalanced in skeletal muscle cells atrophy resulting from hypoxia. Myotubes under hypoxia were treated by electrical stimulation, amino acids supplement or oxygenation period. Signalling pathways involved in protein synthesis (PI3K-Akt-mTOR) and degradation (FoxO1 and FoxO3a) were investigated, so as autophagy, ubiquitin-proteasome system and myotube morphology. Electrical stimulation and oxygenation treatment resulted in higher myotube diameter, myogenic fusion index and myotubes density until 48 h post-treatment compared to untreated hypoxic myotubes. Both treatments also induced inhibition of FoxO3a and decreased activity of ubiquitin-proteasome system; however, their impact on protein synthesis pathway was specific for each one. Indeed, electrical stimulation impacted upstream proteins to mTOR (i.e., Akt) while oxygenation treatment activated downstream targets of mTOR (i.e., 4E-BP1 and P70S6K). In contrast, amino acid supplementation had very few effects on myotube morphology nor on protein homeostasis. This study demonstrated that electrical stimulation or oxygenation period are two effective treatments to fight against hypoxia-induced muscle atrophy, acting through different molecular adaptations.

Isometric Strength Database for Muscle Maximal Voluntary Endurance Field Tests: Normative Data.

BACKGROUND: Different field tests are used to evaluate muscle capacity, in particular maximal voluntary isometric endurance. However, although there are some normative values for a few muscle endurance tests, these do not consider the weight, height, gender, or age of individuals, which are well-known factors that influence muscle performance. HYPOTHESIS/PURPOSE: The purpose of this study was to investigate the test-retest reproducibility of eight field tests and establish muscle endurance norms, in a healthy population, based on their anthropometric characteristics, which could allow the optimal evaluation of the entire muscle function in a quick manner. DESIGN: Case series. METHODS: This study was conducted in two phases. The first phase was to check the reproducibility inter- and intra-assessor for eight isometric muscle field tests on 20 volunteer subjects aged 40.9 ± 11.6 years old (age range, 21-58 years). The second part was to establish muscle maximal voluntary isometric endurance norms according to these tests on a total of 400 healthy participants grouped by age (50 males and females in each of the age brackets, 20-29; 30-39; 40-49; 50-59 years old, for a total of 200 males and 200 females). RESULTS: The intra- and inter-assessor reproducibility tests are good for all muscle measurements (the intraclass correlation coefficients varied between 0.915 and 0.996 and the coefficient of variation between 3.6 and 11.8%). The area under the receiver operating characteristic curves demonstrates a good sensibility with values greater than 0.7 for each test. Each muscle belt presents same ratio regardless of the age and gender group. The simultaneous multiple regression analyses highlight that the anthropometric characteristics of subjects influence significantly the performance of isometric tests. CONCLUSION: This study has permitted establishing prediction equations in a healthy population according to their anthropometric characteristics as well as agonist/antagonist ratios for eight muscle isometric field tests after demonstrating a good reproducibility of all tests.

Impact of different methods of induction of cellular hypoxia: focus on protein homeostasis signaling pathways and morphology of C2C12 skeletal muscle cells differentiated into myotubes.

Hypoxia, occurring in several pathologies, has deleterious effects on skeletal muscle, in particular on protein homeostasis. Different induction methods of hypoxia are commonly used in cellular models to investigate the alterations of muscular function consecutive to hypoxic stress. However, a consensus is not clearly established concerning hypoxia induction methodology. Our aim was to compare oxygen deprivation with chemically induced hypoxia using cobalt chloride (CoCl2) or desferrioxamine (DFO) on C2C12 myotubes which were either cultured in hypoxia chamber at an oxygen level of 4% or treated with CoCl2 or DFO. For each method of hypoxia induction, we determined their impact on muscle cell morphology and on expression or activation status of key signaling proteins of synthesis and degradation pathways. The expression of HIF-1α increased whatever the method of hypoxia induction. Myotube diameter and protein content decreased exclusively for C2C12 myotubes submitted to physiological hypoxia (4% O2) or treated with CoCl2. Results were correlated with a hypophosphorylation of key proteins regulated synthesis pathway (Akt, GSK3-ß and P70S6K). Similarly, the phosphorylation of FoxO1 decreased and the autophagy-related LC3-II was overexpressed with 4% O2 and CoCl2 conditions. Our results demonstrated that in vitro oxygen deprivation and the use of mimetic agent such as CoCl2, unlike DFO, induced similar responses on myotube morphology and atrophy/hypertrophy markers. Thus, physiological hypoxia or its artificial induction using CoCl2 can be used to understand finely the molecular changes in skeletal muscle cells and to evaluate new therapeutics for hypoxia-related muscle disorders.

Lifelong Voluntary Exercise Modulates Age-Related Changes in Oxidative Stress.

The hypothesis that aging and regular physical activity could influence oxidative stress has been studied by comparing antioxidant activities (superoxide dismutase (SOD), glutathione peroxidase (GPX), glutathione reductase (GR), ascorbic acid and α-Tocopherol) and malondialdehyde level (MDA) in four groups: young sedentary (n=15; age: 20.3±2.8 years; YS), young active (n=16; age: 21.4±1.9 years; YA), old sedentary (n=15; age: 65.1±3.5 years; OS) and old active (n=17; age: 67.2±4.8 years; OA). Antioxidant activities and MDA level were assessed at rest and after an incremental exercise. There was no difference in resting antioxidant activities and lipid peroxidation between YS and OS. However, resting SOD and GR activities were higher in YA compared to OA (p<0.01 and p<0.05, respectively) and resting MDA level was higher in OA compared to YA (p<0.01). After exercise, a significant increase in SOD and GPX activities was observed in YS, YA and OA (p<0.01). Likewise, after exercise a significant increase of MDA level in YA, OS and OA (p<0.01) was observed. In addition, the comparison of YA to OA and YS to OA revealed similar antioxidant activities and lipid peroxidation between YS and OA, whereas antioxidant activities were higher in YA compared to OA. These data suggest that beneficial effects of regular physical activity in antioxidant defense and lipid peroxidation damage could be impaired by the aging process and that regular physical activity in older adults could maintain age-related decreases in antioxidant defense.

Relationships between heart rate target determined in different exercise testing in COPD patients to prescribed with individualized exercise training.

BACKGROUND: It has been scientifically proven that pulmonary rehabilitation improves exercise tolerance and facilitates the carrying out of daily physical activities. To optimize the physical and physiological benefits, it is necessary to individualize the training intensity for each patient. The aim of this study is to compare the heart rate (HR) responses to three exercise modalities measuring aerobic fitness in chronic obstructive pulmonary disease patients, in order to easily prescribe individual target HRs for endurance training. PATIENTS AND METHOD: Fifty COPD patients (mean age: 60.1±8.5 years) were included in the study. Each patient carried out a cardiopulmonary exercise test, a 6-minute walk test (6MWT) and a 6-minute stepper test (6MST). During these tests, HR was recorded continuously. After the cardiopulmonary exercise test, the HR was noted at the ventilatory threshold (VT) and at the end of the two exercise field tests (6MWTpeak and 6MSTpeak). The values of the HR during the last 3 minutes of both field tests were averaged (6MWT456 and 6MST456). Finally, the HR at 60% of the HR reserve was calculated with the values of the HR measured during 6MWT and 6MST (HRr60%walk, HRr60%step). RESULTS: The HRs measured during the 6MST were significantly higher than those measured during the 6MWT. The HRr60%step was not significantly different from 6MWT456 and 6MWTpeak HR (P=0.51; P=0.48). A significant correlation was observed between 6MWT456 and 6MWTpeak (r=0.58). The 6MWT456 and 6MWTpeak HR were correlated with HRr60%step (r=0.68 and r=0.62). The VT could be determined in 28 patients. The HRVT was not different from 6MWT456, 6MWTpeak, and HRr60%step (P=0.57, P=0.41 and P=0.88) and was correlated to 6MWT456, 6MWTpeak, and HRr60%step (r=0.45, r=0.40, r=0.48). CONCLUSION: An individualized target HR for endurance training can be prescribed from the HR measured during routine tests, such as 6MWT or 6MST.

Radical Oxygen Species, Exercise and Aging: An Update.

It is now well established that reactive oxygen species (ROS) play a dual role as both deleterious and beneficial species. In fact, ROS act as secondary messengers in intracellular signalling cascades; however, they can also induce cellular senescence and apoptosis. Aging is an intricate phenomenon characterized by a progressive decline in physiological functions and an increase in mortality, which is often accompanied by many pathological diseases. ROS are involved in age-associated damage to macromolecules, and this may cause derangement in ROS-mediated cell signalling, resulting in stress and diseases. Moreover, the role of oxidative stress in age-related sarcopenia provides strong evidence for the important contribution of physical activity to limit this process. Regular physical activity is considered a preventive measure against oxidative stress-related diseases. The aim of this review is to summarize the currently available studies investigating the effects of chronic and/or acute physical exercise on the oxidative stress process in healthy elderly subjects. Although studies on oxidative stress and physical activity are limited, the available information shows that acute exercise increases ROS production and oxidative stress damage in older adults, whereas chronic exercise could protect elderly subjects from oxidative stress damage and reinforce their antioxidant defences. The available studies reveal that to promote beneficial effects of physical activity on oxidative stress, elderly subjects require moderate-intensity training rather than high-intensity exercise.

Influence of physical fitness on antioxidant activity and malondialdehyde level in healthy older adults.

The aim of this study was to investigate how physical fitness level could affect antioxidant activity and malondialdehyde (MDA) level at rest and in response to exhaustive exercise in healthy older adults. Fifty older adults (average age: 66.1 ± 3.8 years) were divided according to their physical fitness level into an unfit group (UG) (n = 15), a low fitness level group (LFG) (n = 18), and a high fitness level group (HFG) (n = 17). Fitness status was classified based on answers to a questionnaire about physical activity in the previous 12 months. Before and after an incremental cycle ergometer test to exhaustion, the following markers were assessed: superoxide dismutase (SOD), glutathione peroxidase (GPX), glutathione reductase, ascorbic acid, α-tocopherol, and MDA. At rest, SOD, GPX, and α-tocopherol activities were higher in the HFG (p < 0.05), whereas MDA level was lower in the LFG in comparison with the 2 other groups (p < 0.05). During the postexercise period, antioxidant activity increased only in the LFG and the HFG (GPX, SOD, and α-tocopherol). MDA level increased in all groups after the exercise (p < 0.05). In addition, MDA level was higher during the recovery period in the HFG as compared with the others groups. This study concluded that both low and high physical fitness levels help maintain better antioxidant defenses in older adults. However, a higher physical fitness level, rather than a lower physical fitness level, could increase lipid peroxidation.

Changes in oxidative stress markers and biological markers of muscle injury with aging at rest and in response to an exhaustive exercise.

PURPOSE: The aim of this study was to evaluate whether oxidative stress markers and biomarkers of muscle injury would be affected by aging at rest and in response to an incremental exhaustive exercise. METHODS: Fifteen young (20.3 ± 2.8 years) and fifteen older adults (65.1 ± 3.5 years) performed an incremental cycle ergometer test to exhaustion. Before and after exercise, oxidative stress [superoxide dismutase (SOD), glutathione peroxidase (GPX), glutathione reductase (GR), ascorbic acid, α-Tocopherol, malondialdehyde (MDA)] and muscle injury [creatine kinase (CK), lactate deshydrogenase (LDH)] biomarkers were assessed. RESULTS: At rest, there was no difference in oxidative stress markers and LDH level between the groups, however CK was significantly higher in the young group than the elderly group (p<0.05). During recovery, in comparison with resting values, a significant increase in SOD (1092 ± 145.9 vs. 1243 ± 98 U/g Hb), GPX (67.4 ± 12.7 vs. 79.2 ± 15.6 U/g Hb) and GR (6.5 ± 0.9 vs. 7.7 ± 0.5 U/g Hb) activities were observed only in the young group (p<0.05). MDA has increased only in the older group (0.54 ± 0.2 vs. 0.79 ± 0.2 µmol/l) (p<0.01). CK increased in both groups (young group: 122.5 ± 22.2 vs. 161.9 ± 18.7 UI/l; older group: 88.8 ± 34.1 vs. 111.1 ± 25.9 UI/l) (p<0.01), however LDH has increased only in the young group (400.5 ± 22.2 vs. 485 ± 18.7 UI/l) (p<0.01) without alteration in the older group (382.8 ± 34.1 vs. 418.5 ± 25.9 UI/l). CONCLUSIONS: These findings indicate that aging is associated with a decrease in antioxidant efficiency and an increase in oxidative stress damage. Furthermore, older adults would not more susceptible to exercise-induced muscle injury than young people.

Low intensity aerobic exercise and oxidative stress markers in older adults.

This comparative study examined the effects of regular low intensity aerobic exercise on oxidative stress markers in older adults. The study was carried out on 15 sedentary subjects (age: 65.1 ± 3.5 years) versus 18 subjects performing fitness exercises (age: 65.8 ± 3.3 years). Before and after an incremental exercise test, oxidative stress markers were assessed. Superoxide dismutase was higher at rest and at the recovery for the physically active subjects compared with sedentary subjects (p < .05). At recovery, glutathione peroxidase and α -Tocopherol increased significantly above the resting values only in the active group (p < .05). Malondialdehyde had increased in both groups (p < .01), associated with a higher level in the sedentary group (p < .05) at the recovery. These data suggest that low intensity aerobic exercise may be useful to prevent the decline of antioxidants linked with aging.

Mechanical ventilatory constraints during incremental exercise in healthy and cystic fibrosis children.

AIM: To analyze breathing pattern and mechanical ventilatory constraints during incremental exercise in healthy and cystic fibrosis (CF) children. METHODS: Thirteen healthy children and 6 children with cystic fibrosis volunteered to perform an incremental test on a treadmill. Exercise tidal flow/volume loops were plotted every minute within a maximal flow/volume loop (MFVL). Expiratory flow limitation (expFL expressed in %Vt) was evaluated and end-expiratory and end-inspiratory lung volumes (EELV and EILV) were estimated from expiratory reserve volume relative to vital capacity (ERV/FVC) and from inspiratory reserve volume relative to vital capacity (IRV/FVC). RESULTS: During the incremental exercise, expFL was first observed at 40% of maximal aerobic speed in both groups. At maximal exercise, 46% of healthy children and 83% of CF children presented expFL, without significant effect of cystic fibrosis on the severity of expFL. According to the two-way ANOVA results, both groups adopted similar breathing pattern and breathing strategies as no significant effect of CF has been revealed. But, according to one-way ANOVA results, a significant increase of ERV/FVC associated with a significant decrease of IRV/FVC from resting value shave been observed in healthy children at maximal exercise, but not in CF children. DISCUSSION: The hypothesis of this study was based on the assumption that mild cystic fibrosis could induce more frequent and more severe mechanical ventilatory constraints due to pulmonary impairment and breathing pattern disturbances. But, this study did not succeed to highlight an effect of mild cystic fibrosis on the mechanical ventilatory constraints (expFL and dynamic hyperinflation) that occur during an incremental exercise. This absence of effect could be due to the absence of an impact of the disease on spirometric data, breathing pattern regulation during exercise and breathing strategy.

Exercise testing in children: comparison in ventilatory thresholds changes with interval-training.

The aim of this investigation was, first, to examine comparatively the changes in first and second ventilatory thresholds (VT1 and VT2 ) and, secondly, to compare with peak oxygen uptake (${\dot {\rm {V}}}_{{\rm O}_{{\rm 2}} {\rm peak}} $) changes following high-intensity interval training (HIT) in prepubescent children. Eighteen prepubescent children (aged 10.1 ± 0.7 years) performed an incremental exhaustive exercise on a cycle ergometer with pulmonary gas exchange measurements before and after an 8-week period. During this period, nine children (five girls and four boys; initial ${\dot {\rm {V}}}_{{\rm O}_{{\rm 2}} {\rm peak}} $: 39.6 ± 6.0 ml O2 · min(-1) · kg(-1) ) took part in a HIT and nine other children (three girls and six boys; initial ${\dot {\rm {V}}}_{{\rm O}_{{\rm 2}} {\rm peak}} $: 39.8 ± 7.8 ml O2 · min(-1) · kg(-1) ), considered as controls, were not trained. After the training period, VT1 , VT2 , and ${\dot {\rm {V}}}_{{\rm O}_{{\rm 2}} {\rm peak}} $ were significantly (P < 0.01) improved (21%, 24%, and 14%, respectively) without significant changes in the control group. However, the changes in VT1 (ΔVT1 = +4.35 ± 4.36 ml O2 · min(-1) · kg(-1) ), VT2 (ΔVT1 = +7.17 ± 5.17 ml O2 · min(-1) · kg(-1) ), ${\dot {\rm {V}}}_{{\rm O}_{{\rm 2}} {\rm peak}} $ ($\Delta {\dot {\rm {V}}}_{{\rm O}_{{\rm 2}} {\rm peak}} $ = +5.51 ± 4.17 ml O2 · min(-1) · kg(-1) ) induced by HIT in trained children were not related. In conclusion, for prepubescent children, in addition to VT1 and ${\dot {\rm {V}}}_{{\rm O}_{{\rm 2}} {\rm peak}} $, VT2 can also be significantly improved by training. Therefore, HIT represents a good way to obtain great improvement in these parameters in only 8 weeks. However, the time courses of these aerobic fitness parameters are dissociated, which implies the need to differentiate among them during aerobic fitness exercise testing.

Is there any relationship between physical activity level and patterns, and physical performance in children?

BACKGROUND: It is often assumed that physical activity (PA) and physical performance during childhood and adolescence are beneficial for health during adulthood, but a positive relationship between PA and physical performance has not been precisely clarified in children. The lack or the weakness of the relationships between PA and physical performance could be due to the measure of PA. If the use of accelerometry is considered as an objective and common measure of PA, the real patterns of children's habitual PA must be reflected. The aim of this study was to investigate the relationship between the levels and patterns of PA assessed with high frequency accelerometry and physical performance in young children. METHODS: Eighty-six boys and 101 girls aged 6-12 years participated in this study. Physical activity was measured over a 7-day period, using a 5-s epoch. Physical performance was assessed by means of EUROFIT tests (anthropometrics, standing broad jump, the 10 × 5 meter shuttle run, the sit-and-reach, the handgrip, the number of sit-ups in 30 seconds, the 20-meter shuttle run). RESULTS: No relationship was found between PA and physical performance. In boys only, body fatness was negatively associated with vigorous PA (r = -0.38, p < 0.001) and very high PA (r = -0.35, p < 0.01), in contrast to light PA (r = 0.28, p < 0.01), which was positively related to body fatness. CONCLUSION: In 6- to- 12 year- old children, the more active children were not the fittest. Our results also underline the need for uniformity in approach to measurement of PA, body composition and health-related fitness between studies.

Comparison of mechanical ventilatory constraints between continuous and intermittent exercises in healthy prepubescent children.

BACKGROUND: The aim of this study was to evaluate the occurrence and severity of mechanical ventilatory constraints in healthy prepubescent children during continuous and intermittent exercise. METHODS: Twelve prepubescent children (7-11 years old) performed 7 exercises on a treadmill: one graded test for the determination of maximal aerobic speed (MAS), three continuous exercises (CE) at 60, 70, and 80% of MAS and three intermittent exercises (IE), alternating 15 sec of exercise with 15 sec of passive recovery, at 90, 100, and 110% of MAS. During each CE and IE, tidal flow/volume loops were plotted within a maximal flow/volume loop (MFVL) measured at rest before each exercise. Expiratory flow limitation (expFL expressed in %Vt) was defined as the part of exercise tidal volume (Vt) meeting the boundary of MFVL. Breathing strategy was estimated by measuring inspiratory capacity relative to forced vital capacity and tidal volume relative to inspiratory capacity. Other breathing pattern parameters (ventilation VE, Vt, respiratory frequency f) were continuously recorded during exercise. RESULTS: An "intensity" effect was found for VE during CE (P < 0.001) but not during IE (P = 0.08). The increase in VE was predominantly assumed by an increase in f for both exercise modalities. During each exercise, several children heterogeneously experienced expFL ranging between 10 and 90%Vt. For all exercises, Vt was predominantly regulated by an increase in Vt/IC with no change in IC/FVC from rest to exercise. Finally, no significant "modality" effect was found for mechanical ventilatory constraint parameters (expFL, Vt/IC, and IC/FVC). DISCUSSION: We could conclude that neither of the modalities studied induced more mechanical ventilatory constraints than the other, but that exercise intensities specific to each modality might be greater sources of exacerbation for mechanical ventilatory constraints.

An original field evaluation test for chronic obstructive pulmonary disease population: the six-minute stepper test.

PURPOSE: The aim of this study was to evaluate a new field test, the six-minute stepper test (6-MST), by studying its reproducibility, sensitivity and validity. METHODS: After a familiarization test, 16 patients with chronic obstructive pulmonary disease (COPD) and 15 healthy subjects performed two six-minute stepper tests per day over three evaluation days. Ten of the 16 patients with COPD also performed a six-minute walking test (6-MWT) with an analysis of gas exchange to compare the metabolic requirements of the two tests. Dyspnoea Borg values were evaluated with Borg's CR-10 scale. RESULTS: The mean (SD) scores for the COPD group for the first and second six-minute stepper tests were 382.49 (106.01) and 412.45 (118.39) strokes/6 minutes, respectively. Crossed comparison between the first or the second six-minute stepper tests of each evaluation day revealed no significant difference, indicating the reproducibility of the test. The sensitivity was demonstrated by a significantly higher performance in the healthy group (P < 0.001), demonstrating the ability of the test to detect two groups with different fitness levels. Finally, mean dyspnoea Borg values (SD) were significantly lower (P < 0.05) during the six-minute stepper test than during 6-MWT (2.5 (1.5) versus 3.1 (1.2)). CONCLUSIONS: This study demonstrated that the six-minute stepper test is a reproducible, sensitive, secure, well-tolerated and feasible test for patients with COPD. The reproducibility and sensitivity of the six-minute stepper test suggests that this test could be used in the evaluation of exercise tolerance in patients with COPD.