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Background Physical activity (PA) is a proven therapeutic tool to increase the quality of life and life expectancy in people with cystic fibrosis (pwCF). Despite this, the PA level of pwCF is lower than recommended. Objectives This study was conducted to identify the barriers to and facilitators of PA in adults with CF with heterogeneous severity. Methods Twenty adults with CF (mean age = 33.3±11.7 years, mean FEV1% = 50.55±20.4%) were recruited from two specialized centers and interviewed about the factors that limit and facilitate their PA. The collected data were transcribed, coded and analyzed using deductive and inductive methods. Results Barriers and facilitators were classified into physical, psychological and environmental dimensions. The main barriers were fatigue, breathing difficulties, lack of available facilities, negative perceptions of PA and perceived health risks. The most important facilitators were respiratory benefits, well-being, and social support. Conclusion Although some barriers and facilitators were similar to those found in children with CF or adults from other vulnerable populations, others were specific to adults with CF, such as the risk of cross-contamination and transplant preparation. The comprehensive study of the barriers and facilitators in adults will enhance PA counseling for pwCF and help improve their compliance with PA recommendations.

Sleep is bi-directionally linked to energy balance. This crossover study design will evaluate the acute effect of a moderate energy deficit (500 kcal) induced by diet, exercise, or mixed (−250 kcal by diet and 250 kcal by exercise) on sleep and the next morning’s appetitive responses. The study sample comprises 24 healthy young adults. The experimental measurements will be conducted in a naturalistic, momentary manner and partly assessed by the participants. The participants will undergo a run-in period in order to stabilize their sleep schedules and provide them with training on the study protocol and measurements. Indirect calorimetry will be used to determine their resting metabolic rate and peak oxygen consumption (VO2 peak). Then, they will take part in a control session (CTL), followed by three energy deficit sessions in random order: a diet-induced energy deficit session (DED), an exercise-induced energy deficit session (EED), and a mixed energy deficit session (MED). All experimental sessions will be separated by a one-week washout. The participants’ sleep will be monitored by ambulatory polysomnography, and the next morning’s appetitive response will be evaluated via ad libitum food intake, appetite sensations, and food reward, measured by a food liking and wanting computerized test.

New findings What is the topic of this review? This review highlights the central and peripheral mechanisms that alter oxygen transport and utilisation and thereby contribute to exercise limitation in people with cystic fibrosis, considering also viable therapeutic targets for intervention. What advances does it highlight? Although traditionally considered a respiratory condition, pathological intramuscular and cardiovascular changes in people with cystic fibrosis appear to be key determinants of exercise intolerance up until the later stages of respiratory disease. Even young, habitually active patients with normal lung function experience multisystemic abnormalities, which play a role in exercise intolerance. Abstract Cystic fibrosis (CF) is a complex condition, commonly associated with exercise limitation. The mechanisms responsible for this in CF are of interest, given that lower aerobic fitness is associated with an increased risk of being hospitalised with pulmonary exacerbation, a poorer quality of life and a poorer prognosis. Pathophysiological changes in lung function are considered central to CF, and may contribute to exercise limitation. However, it is now clear that the pathogenesis of exercise limitation in this population is multifactorial, with alterations in cardiovascular, muscle and pulmonary function contributing. Whilst some of these changes are attributable to respiratory disease per se, the CF transmembrane conductance regulator protein is also found in skeletal muscle and the vascular endothelium and can directly alter central and localised oxygen delivery, as well as the ability to effectively extract and utilise oxygen at the myocyte level. Since intense exercise poses considerable challenges to arterial oxygen content and/or blood flow and its supply to the working skeletal muscle, evaluating the exercise physiology of people with CF has helped us understand the mechanisms underlying exercise intolerance. Through several investigations over recent years, we have collectively demonstrated that people with CF exhibit reduced skeletal muscle oxygen extraction and utilisation during exercise, with a lesser contribution from haemodynamic or chronotropic mechanisms. Taken together, our findings highlight the importance of targeting mechanisms of skeletal muscle oxygen utilisation in CF to improve exercise tolerance and we offer potential therapeutic interventional strategies.

International audience; Physiological signals present fluctuations that can be assessed from their temporal structure, also termed complexity. The complexity of a physiological signal is usually quantified using entropy estimators, such as Sample Entropy. Recent studies have shown a loss of force signal complexity with the development of neuromuscular fatigue. However, these studies did not consider the stationarity of the force signals which is an important prerequisite of Sample Entropy measurements. Here, we investigated the effect of the potential nonstationarity of force signals on the kinetics of neuromuscular fatigue-induced change in force signal's complexity. Eleven men performed submaximal intermittent isometric contractions of knee extensors until exhaustion. Neuromuscular fatigue was assessed from changes in voluntary and electrically evoked contractions. Sample Entropy values were computed from submaximal force signals throughout the fatiguing task. The Dickey-Fuller test was used to statistically investigate the stationarity of force signals and the Empirical Mode Decomposition was applied to detrend these signals. Maximal voluntary force, central voluntary activation and muscle twitch decreased throughout the task (all p < 0.05), indicating the development of global, central and peripheral fatigue, respectively. We found an increase in Sample Entropy with fatigue (p = 0.024) when not considering the nonstationarity of force signals (i.e. 43% of the signals). After applying the Empirical Mode Decomposition, we found a decrease in Sample Entropy with fatigue (p = 0.002). These findings confirm the presence of nonstationarity in force signals during submaximal isometric contractions which influences the kinetics of change in Sample Entropy with neuromuscular fatigue.

Purpose Due to its eccentric nature, downhill running (DR) training has been suggested to promote strength gains through neuromuscular adaptations. However, it is unknown whether short-term chronic DR can elicit such adaptations. Methods Twelve untrained, young, healthy adults (5 women, 7 men) took part in 4 weeks’ DR, comprising 10 sessions, with running speed equivalent to 60–65% maximal oxygen uptake ($$\dot{V}$$ V ˙ O2max, assessed at weeks 0 and 4). Isometric and isokinetic knee-extensor maximal voluntary torque (MVT), vastus lateralis (VL) muscle morphology/architecture (anatomical cross-sectional area, ACSA; physiological CSA, PCSA; volume; fascicle length, Lf; pennation angle, PA) and neuromuscular activation (VL EMG) were assessed at weeks 0, 2 and 4. Results MVT increased by 9.7–15.2% after 4 weeks (p p r = 0.86, p = 0.001). VL ACSA (+2.9 ± 2.7% and +7.1 ± 3.5%) and volume (+2.5 ± 2.5% and +6.6 ± 3.2%) increased after 2 and 4 weeks, respectively (p Lf (+2.7 ± 2.2%) increased after 4 weeks (p r = 0.67, p = 0.03) and PCSA (r = 0.71, p = 0.01) correlated with changes in concentric MVT from 2 to 4 weeks. $$\dot{V}$$ V ˙ O2max (49.4 ± 6.2 vs. 49.7 ± 6.3 mL·kg−1·min−1) did not change after 4 weeks (p = 0.73). Conclusion Just 4 weeks’ moderate-intensity DR promoted neuromuscular adaptations in young, healthy adults, typically observed after high-intensity eccentric resistance training. Neural adaptations appeared to contribute to most of the strength gains at 2 and 4 weeks, while muscle hypertrophy seemed to contribute to MVT changes from 2 to 4 weeks only.

Editorial on the Research Topic\ud From Physiological Adaptations to Endurance Performance: It Is Time to Bridge the Gap

International audience

This study aimed to investigate the walking economy and possible factors influencing self-selected walking speed (SSWS) in patients with fibrotic interstitial lung disease (ILD) compared to controls. In this study, 10 patients with ILD (mean age: 63.8 ± 9.2 years, forced expiratory volume in the first second: 56 ± 7% of predicted) and 10 healthy controls underwent resting pulmonary function tests, cardiopulmonary exercise, and submaximal treadmill walking tests at different speeds. The walking economy was assessed by calculating the cost-of-transport (CoT). Dynamic stability was assessed by stride-to-stride fluctuations using video recordings. Patients with ILD showed reduced peak oxygen uptake with a tachypneic breathing pattern and significant oxygen desaturation during exercise. The CoT did not differ between the groups (p = 0.680), but dyspnea and SpO2 were higher and lower, respectively, in patients with ILD at the same relative speeds. SSWS was reduced in ILD patients (2.6 ± 0.9 vs. 4.2 ± 0.4 km h−1p = 0.001) and did not correspond to the energetically optimal walking speed. Dynamic stability was significantly lower in patients with ILD than in healthy controls, mainly at lower speeds. Patients with ILD presented a similar cost of transport compared to healthy controls; however, they chose lower SSWS despite higher walking energy expenditure. Although walking stability and dyspnea were negatively affected, these factors were not associated with the slower walking speed chosen by individuals with ILD.

International audience

Delextrat, A, Gruet, M, and Bieuzen, F. Effects of small-sided games and high-intensity interval training on aerobic and repeated sprint performance and peripheral muscle oxygenation changes in elite junior basketball players. J Strength Cond Res 32(7): 1882-1891, 2018-The aim of the current study was to compare the effects of 6 weeks of small-sided game (SSG) and high-intensity interval training (HIIT) on aerobic fitness and muscle oxygenation during a repeated sprint (RS) sequence in elite male junior basketball players. Twenty participants (14.3 ± 0.5 years; 176.8 ± 12.5 cm; 74.5 ± 9.8 kg) performed pre- and post-tests interspersed by 6 weeks of SSG or HIIT training. Testing sessions consisted of the 30-15 intermittent fitness test and an RS sequence (2 bouts of 15 seconds). During RS, muscle oxygenation parameters (tissue saturation index [TSI, %], postsprint muscle reoxygenation rate) were measured using near-infrared spectroscopy. The results showed that both training interventions similarly improved maximal aerobic speed (VIFT, 3.4 and 4.1%, respectively, for HIIT and SSG, P < 0.05) as well as RS ability (smaller percentage decrement by 62.5 and 21.6%, respectively, for HIIT and SSG, P < 0.05). Both training interventions also resulted in a greater ΔTSI during the second sprint (47.8-114%, P < 0.05) and significant improvements in postsprint reoxygenation after both sprints (+23.0 to +107.7%). Finally, the variation in muscle reoxygenation after sprint 1 was significantly associated with improvements in aerobic (ΔVIFT, r = 0.61, P = 0.008) and anaerobic (Δ% Dec during RS, r = -0.487, P = 0.028) performances. The current study has observed that SSG and HIIT resulted in similar improvements in aerobic and anaerobic variables and a better muscle oxygenation capacity during RS. Coaches should be aware that both trainings are applicable methodologies to improve in-season aerobic and anaerobic fitness capacities in junior basketball players.

Background:Physiological mechanisms behind the use of compression garments (CGs) during off-road running are unknown.Purpose:To investigate the influence of wearing CGs vs conventional running clothing (CON) on muscle contractile function and running economy before and after short-distance trail running.Methods:Knee-extensor neuromuscular function and running economy assessed from two 5-min treadmill runs (11 and 14 km/h) were evaluated before and after an 18.6-km short-distance trail run in 12 trained athletes wearing either CGs (stocking + short-tight) or CON. Quadriceps neuromuscular function was assessed from mechanical and EMG recording after maximal percutaneous electrical femoral-nerve stimulations (single-twitch doublets at 10 [Db10] and 100 Hz [Db100] delivered at rest and during maximal quadriceps voluntary contraction [MVC]).Results:Running economy (in mL O2 · km–1 · kg–1) increased after trail running independent of the clothing condition and treadmill speeds (P < .001). Similarly, MVC decreased after CON and CGs conditions (–11% and –13%, respectively, P < .001). For both clothing conditions, a significant decrease in quadriceps voluntary activation, Db10, Db100, and the low-to-high frequency doublet ratio were observed after trail running (time effect, all P < .01), without any changes in rectus femoris maximal M-wave.Conclusions:Wearing CGs does not reduce physiological alterations induced during short-distance trail running. Further studies should determine whether higher intensity of compression pressure during exercises of longer duration may be effective to induce any physiological benefits in experienced trail runners.

Objective and background Impaired cerebral blood flow and cerebrovascular reactivity to hypercapnia during wakefulness at rest as well as reduced exercise tolerance have been reported in severe obstructive sleep apnea (OSA) patients. Impaired cerebral oxygenation and hemodynamics can contribute to reduced exercise performance. We hypothesized that (i) OSA patients show impaired cerebrovascular response both during exercise and in response to hypercapnia together with reduced exercise tolerance and (ii) continuous positive airway pressure (CPAP) treatment improves these alterations in cerebral oxygenation. Methods Fifteen OSA patients and 12 healthy matched controls performed a hypercapnic response test and a maximal cardiopulmonary exercise test before and after eight weeks of CPAP treatment or control period. Prefrontal cortex and muscle oxygenation were assessed by near-infrared spectroscopy (NIRS) during both tests. Results Cerebrovascular reactivity to hypercapnia was impaired in OSA patients (lower increase in oxyhemoglobin [0.29 ± 0.19 vs 0.44 ± 0.14 μmol mmHg−1] and total hemoglobin [0.14 ± 0.15 vs 0.26 ± 0.09 μmol mmHg−1]) compared to controls. Reduced prefrontal cortex oxygen extraction and total blood volume (ie, lower increase in deoxyhemoglobin [1.76 ± 1.57 vs 3.43 ± 2.08 μmol] and total hemoglobin [5.36 ± 7.08 vs 8.55 ± 5.13 μmol at exhaustion], respectively) during exercise together with a reduced exercise tolerance (ie, lower peak oxygen consumption) were observed in OSA patients compared to controls. CPAP treatment did not induce any improvement in cerebrovascular response during hypercapnic response test and exercise. Conlusions This study demonstrates that cerebrovascular response to exercise is altered in OSA and may contribute to exercise intolerance in these patients. Prefrontal cortex oxygenation and exercise tolerance are not significantly improved following eight weeks of CPAP treatment. Clinical trial registration NCT02854280 .

To the editor: We read with interest the recent Viewpoint on the different eccentric exercise modalities (4), and we commend the authors for having raised this interesting topic. Since the eccentric-exercise family is variegated, characterizing each modality helps in identifying their specific intrinsic stimuli. However, a between-modality comparison is not an easy matter. Exercise volume is a key factor in resistance training. A recent meta-analysis showed comparable exercise volumes led to similar strength gains (5). When performing an isoweight eccentric exercise, the volume can be manipulated a priori, given the total number of repetitions and for each repetition the range of motion, time under tension, and intensity (i.e., the external load) (2). When performing an isokinetic eccentric exercise, the intensity depends on the subject’s ability to gradually or maximally perform each repetition. To possibly match the eccentric isoweight vs isokinetic exercise intensity, we previously calculated the maximal eccentric:concentric isokinetic ratio and then transferred such a ratio as a percentage of the maximal concentric isoweight load (i.e., %1-RM) (2). It resulted in comparable isoweight versus isokinetic training intensity and volume, which led to overall similar muscle strength and architecture changes (2, 3). To further entangle this picture, the eccentric phase of isoinertial exercise is preceded by a maximal explosive-concentric phase (1). Thus, isoinertial cannot be considered as a purely eccentric exercise because of the effects of the eccentric or concentric phase, or the combination of both. Therefore, encouraging new studies to compare isoweight versus isokinetic versus isoinertial eccentric training, we recommend a thorough exercise volume calculation for appropriate matching.

The optimal method for respiratory muscle endurance (RME) assessment remains unclear. This study assessed the test-retest reliability of two RME-test methodologies. Fifteen healthy adults attended the laboratory on four occasions, separated by 5 ± 2 days, and completed each test in a random, “one on two” order. They performed spirometry testing, maximal respiratory pressure assessment and two different RME tests: an inspiratory resistive breathing (IRB) and an isocapnic hyperpnea endurance (IHE) test. Typical error, expressed as coefficient of variation, for IRB maximal inspiratory pressure (MIP) and IHE maximal ventilation were 12.21 (8.85–19.67) % and 10.73 (7.78–17.29) %, respectively. Intraclass correlation coefficients for the same parameters were 0.83 (0.46-0.94) and 0.80 (0.41-0.93), respectively. No correlations were found between RME parameters derived from the IHE and IRB tests (all p > 0.05). Significant positive correlations were found between both IRB and IHE outcomes and spirometry parameters, MIP and maximal expiratory pressure (p Given these results, IRB and IHE appear to be suitable for RME testing in healthy people, although they may reflect different physiological mechanisms (respiratory mechanics and respiratory muscle capacity for IHE test vs. inspiratory muscle capacity for IRB test). Future studies are therefore warranted that compare IRB and IHE tests in clinical settings.

We aimed to determine the neurophysiological mechanisms associated with reduced endurance performance during cognitive-motor dual task at different levels of cognitive load, compared to a motor task alone. Eighteen healthy men performed isometric quadriceps contractions at 15% of maximal voluntary contraction (blocks of 170 s interspaced by neuromuscular evaluations) until exhaustion. This task was performed on three separate days: (a) in the absence of concomitant cognitive task, (b) with concomitant 1-back task, and (c) with concomitant 2-back task. Autonomic nervous system activity, perceived exertion, and cognitive performance were continuously monitored. Peripheral and central determinants of neuromuscular function were assessed at rest, between each block, and at task failure using femoral nerve stimulation. Endurance time was shorter during 2-back (982 ± 545 s) and 1-back (1,128 ± 592 s) conditions, compared with control (1,306 ± 836 s). Voluntary activation level was lower in 2-back (87.1%; p < 0.001) and 1-back (88.6%; p = 0.04) conditions compared to control (91.2%) at isotime (100% of the shortest test duration). Sympathetic activity showed a greater increase in 2-back condition compared to control. Perceived muscular exertion was higher during 2-back than during control. Cognitive performance decreased similarly with time during both cognitive-motor dual task but was always lower during 2-back condition. Motor performance is reduced when adding a concomitant demanding memory task to a prolonged isometric exercise. This can be explained by the interaction of various psychological and neurophysiological factors including higher perceived exertion, greater perturbations of autonomic nervous system activity, and cerebral impairments leading to earlier onset of central fatigue.

Background Thanks to the specific materials they embed, far infrared (FIR)-emitting garments can interact with the body’s physiological functions. Such effects have been sought in medicine and physiotherapy for a long time for the treatment/relief of a variety of pathologies and disabling conditions. Recently, FIR-emitting garments have been introduced in the sporting domain under the influence of manufacturers seeing here a new opportunity to support physical performance in athletes, though this is not clearly established. To fill this gap, in this systematic review, we summarize the scientific evidence on the use of FIR-emitting garments in sport and provide directions for future research by shedding light on current scientific limitations. Method Five scientific databases (PubMed, Cochrane, ScienceDirect, Scopus and SPORTDiscus) were searched by two independent reviewers. Studies investigating the effects of FIR-emitting garments on at least one physiological outcome related to exercise performance and/or recovery in humans were selected. The methodological quality of retained studies was assessed using the Physiotherapy Evidence Database (PEDro) scale. Results and discussion Eleven studies met the inclusion criteria and were included in the systematic review. Studies investigating similar outcomes related to exercise performance or recovery were scarce and results inconclusive, which prevents from drawing firm conclusion about the utilisation of FIR-emitting garments in athletes. However, these early results show that FIR-emitting garments may be of interest for exercise performance and recovery, mainly through their effects on the body’s thermoregulation and haemodynamic function. The summary provided in this review can be used to inform the design of future studies. (PROSPERO registration number: CRD42021238029).

Intrinsic motivation (IM) is often viewed as a spontaneous tendency for action. Recent behavioral and neuroimaging evidence indicate that IM, in comparison to extrinsic motivation (EM), solicits the motor system. Accordingly, we tested whether IM leads to greater excitability of the motor cortex than EM. To test this hypothesis, we used two different tasks to induce the motivational orientation using either words representing each motivational orientation or pictures previously linked to each motivational orientation through associative learning. Single-pulse transcranial magnetic stimulation over the motor cortex was applied when viewing the stimuli. Electromyographic activity was recorded on the contracted first dorsal interosseous muscle. Two indexes of corticospinal excitability (the amplitude of motor-evoked potential and the length of cortical silent period) were obtained through unbiased automatic detection and analyzed using a mixed model that provided both statistical power and a high level of control over all important individual, task, and stimuli characteristics. Across the two tasks and the two indices of corticospinal excitability, the exposure to IM-related stimuli did not lead to a greater corticospinal excitability than EM-related stimuli or than stimuli with no motivational valence (ps > .20). While these results tend to dismiss the advantage of IM at activating the motor cortex, we suggest alternative hypotheses to explain this lack of effect, which deserves further research.

PURPOSE The modified shuttle test (MST) is increasingly used in clinical practice to assess functional capacity in patients with cystic fibrosis (CF). The purpose of this study was to evaluate the physiological responses of the MST in adults with CF as compared with the gold standard cardiopulmonary exercise test (CPET). METHODS Participants performed an MST and a CPET on a cycle ergometer in random order. Oxygen (O2) uptake ((Equation is included in full-text article.)O2), carbon dioxide (CO2) retention (end-tidal PCO2; PETCO2), minute ventilation, heart rate, and peripheral O2 saturation (SpO2) were continuously monitored. Whole blood lactate, dyspnea, and leg discomfort were recorded immediately after both exercises. RESULTS Twenty patients with CF (aged 33 ± 8 years; forced expiratory volume in 1 second = 48% ± 17%) completed both tests. Peak values for (Equation is included in full-text article.)O2 (27 ± 7 vs 24 ± 6 mL/kg/min), heart rate (169 ± 19 vs 163 ± 16 bpm), end PETCO2 (42 ± 7 vs 39 ± 8 mm Hg), and O2 desaturation (end SpO2, 86% ± 7% vs 90% ± 6%) were significantly higher during the MST than during the CPET (all Ps < .05). Leg discomfort and whole blood lactate were significantly higher after the CPET (both Ps < .05). Thirty-five percent and 40% of patients showed significant O2 desaturation and CO2 retention, respectively, during the MST, which was not detected during the CPET. A strong relationship was found between MST peak (Equation is included in full-text article.)O2 and body weight walking distance product (r = 0.90; P < .01). CONCLUSIONS The MST may provide a strong indicator of exercise tolerance in adults with CF as indicated by high peak (Equation is included in full-text article.)O2 values. In clinical practice, body weight walking distance should be considered as the primary outcome. This test is also better than cycle ergometry CPET for detecting O2 desaturation and CO2 retention, further emphasizing its clinical interest.

Background: Recent discovery of cystic fibrosis transmembrane conductance regulator expression in human skeletal muscle suggests that CF patients may have intrinsic skeletal muscle abnormalities potentially leading to functional impairments. The aim of the present study was to determine whether CF patients with mild to moderate lung disease have altered skeletal muscle contractility and greater muscle fatigability compared to healthy controls. Methods: Thirty adults (15 CF and 15 controls) performed a quadriceps neuromuscular evaluation using single and paired femoral nerve magnetic stimulations. Electromyographic and mechanical parameters during voluntary and magnetically-evoked contractions were recorded at rest, during and after a fatiguing isometric task. Quadriceps cross-sectional area was determined by magnetic resonance imaging. Results: Someindexesofmusclecontractilitytendedtobereducedatrest inCFcomparedtocontrols(e.g.,mechanicalresponsetodoubletsstimulation at 100 Hz: 74 ± 30 Nm vs 97 ± 28 Nm, P = 0.06) but all tendencies disappeared when expressed relative to quadriceps cross-sectional area (P N 0.5 for all parameters). CF and controls had similar alterations in muscle contractility with fatigue, similar endurance and post exercise recovery. Conclusions: We found similar skeletal muscle endurance and fatigability in CF adults and controls and only trends for reduced muscle strength in CF which disappeared when normalized to muscle cross-sectional area. These results indicate small quantitative (reduced muscle mass) rather than qualitative (intrinsic skeletal muscle abnormalities) muscle alterations in CF with mild to moderate lung disease.

The observation that exerting self-control in an initial task impairs subsequent self-control performance in a following task has been used to explain a wide range of phenomena. If evidence for this "ego-depletion" effect was initially believed to be strong, it is now questioned. Recent meta-analyses indicated that this effect was sensitive to publication bias and that it was greatly reduced after control for this bias. In a pre-registered replication attempt where an ego-depletion protocol was conducted in multiple independent laboratories, the effect was not distinguishable from zero. Here, a different approach is adopted to examine the validity of this effect by improving the experimental protocol with the addition of important methodological precautions: 1) a pre-test measurement, 2) a learning period, 3) a prolonged depleting task, 4) a similar control condition, and 5) valid indexes of self-control. Accordingly, a well-learned Simon task was done before and after 1h of continuous practice of a Stroop task in a high inhibition demands condition (75% of incongruent trials) or in a control condition (0% of incongruent trials). Datasets from between-subjects (Study 1, N = 82) and within-subjects (Study 2, N = 52) experiments were analyzed using generalized linear mixed models. A significant ego-depletion effect was found in Study 1 (greater interference effect and accuracy decline in high inhibition demands than in control condition) but not in Study 2. Because it is difficult to explain this difference in results, the findings suggest that, even in a context chosen to optimize the observation of an ego-depletion effect, it seems difficult to be conclusive about the existence of this effect.

We evaluated the validity of predicting peak oxygen uptake ( $$\dot {V}$$ O2peak) from submaximal ratings of perceived exertion (RPE) during incremental cardiopulmonary exercise test (CPET) in patients with cystic fibrosis (CF) and compared the predictive accuracy between overall and differentiated RPE scores. Thirty-five adults with CF (FEV1 = 58 ± 23%) performed a CPET on cycle ergometer with gas exchange measurements. Leg, chest and overall RPE were collected every minute throughout the test. Linear regressions between $$\dot {V}$$ O2 and RPE ≤ 15 were extrapolated to maximal theoretical RPE (i.e. RPE18 and RPE19) to predict $$\dot {V}$$ O2peak. Agreements between measured and all predicted $$\dot {V}$$ O2peak were tested using Bland–Altman Plots, for the whole group and for subjects presenting significant exercise intolerance (n = 24). Leg, chest and overall RPE increased similarly with exercise intensity. No differences were found between predicted $$\dot {V}$$ O2peak and measured $$\dot {V}$$ O2peak with RPE18 as maximal RPE, for both overall and differentiated RPE (P range 0.94–0.98). Ranges for Pearson correlations and limits of agreements were 0.88–0.91 and 380–461 mL min−1 for the whole group and 0.92–0.94 and 269–365 mL min−1 for subjects with significant exercise intolerance. The greatest association and narrowest limits of agreements were obtained from chest RPE scores. Submaximal RPE scores obtained during CPET can provide acceptable estimate of $$\dot {V}$$ O2peak in adults with CF, particularly in those having significant exercise intolerance. Future studies should assess whether the prediction can be improved, particularly by encouraging the regular use of RPE scales during physical activities/exercise rehabilitations sessions.

Introduction L’ajout d’une tâche cognitive a un exercice prolonge peut alterer la performance en endurance, tant chez le sportif sain que chez le malade chronique. Les mecanismes neurophysiologiques sous-jacents restent cependant meconnus. L’objectif de cette etude est d’evaluer les ajustements s’operant lorsqu’une tâche de memorisation (n-back) est surajoutee de maniere concomitante a un exercice physique prolonge. Methodes Dix-huit adultes sains ont realise des contractions intermittentes isometriques sous-maximales du quadriceps jusqu’a epuisement, sous 3 conditions differentes : – tâche motrice seule (controle) ; – tâche motrice + 1-back ; – tâche motrice + 2-back. Les determinants centraux et peripheriques de la fatigue neuromusculaire (evalues par neurostimulation), l’activite du systeme nerveux autonome (SNA ; par pupillometrie), l’effort percu et les performances cognitives ont ete evalues avant, pendant la tâche et a epuisement. Resultats Le temps d’endurance a ete reduit en 1-back (1470 ± 791 s) et 2-back (1273 ± 723 s) compare a la situation controle (1704 ± 1157 s). Un declin du niveau d’activation centrale et des modifications du SNA, tous deux plus precoces, ainsi qu’une perception d’effort plus elevee, ont ete reveles en condition 2-back. La performance cognitive, inferieure en 2-back, a diminue de maniere similaire lors des 2 situations de double tâche. Conclusion La reduction de performance en double tâche s’expliquerait par l’interaction de differents mecanismes neurophysiologiques : une apparition plus precoce de la fatigue centrale, des alterations majorees du SNA et une perception d’effort plus elevee. Une meilleure comprehension de ces mecanismes favorisera a terme le developpement de nouvelles interventions visant a lutter contre la fatigue, particulierement en situation ecologique chez des patients presentant des troubles cognitifs.

Introduction Dans son histoire respiratoire la mucoviscidose (MV) majore la sollicitation des muscles respiratoires (MR). De nombreux travaux ont etudie la force des MR du patient MV mais peu de donnees sont disponibles sur leur endurance (RME) [1] . Cette etude souhaite comparer deux tests d’endurance des muscles respiratoires et preciser leur role dans l’intolerance a l’effort de ces patients. Materiel et methode Vingt-cinq adultes MV (VEMS = 57,2 ± 19,4 %) ont ete inclus. RME a ete mesure par deux methodologies : un test d’endurance inspiratoire contre resistance (IRB) et un test d’endurance de type hyperpnee-isocapnique (IHE). Les criteres retenus etaient : le temps d’exercice, la pression inspiratoire maximale ou la ventilation minute maximale. La force maximale inspiratoire (MIP), la fonction pulmonaire et les reponses maximales au test a l’effort sur ergocycle (ex. VO2pic, VEpic) ont aussi ete mesures. Resultats Aucune correlation n’a ete trouvee entre IHE et IRB pour le temps d’endurance, la pression inspiratoire maximale ou la ventilation minute maximale (p > 0,05). La ventilation maximale (L.min−1) pendant l’IHE et la pression inspiratoire absolue maximale pendant l’IRB etaient toutes deux correlees avec MIP (r = 0,41 et 0,74), CVF (r = 0,68 et r = 0,59), VEMS (r = 0,64 et 0,50), VEpic (r = 0,73 et r = 0,56) et VO2pic (r = 0,45 et r = 0,42) pendant l’exercice (tous p Conclusion Ces resultats soulignent la signification clinique de la mesure de RME dans la MV. Transpose a la pratique clinique des APA, l’entrainement des MR est un outil qui merite consideration dans cette population. Favoriser l’engagement des MR lors des prises en charge par l’exercice, avec par exemple la methode Pilate, pourraient presenter un interet majeur en raison du potentiel impact clinique positif pour les patients.

International audience; Introduction : The study aimed to investigate how a distortion of perceived exertion in the heat may affect, during a self-paced cycling exercise preceded by prior cognitive task, the thermal perception and the subsequent regulation of power output in high level athletes.Methods : Eleven endurance trained male athletes completed four experimental sessions including a 30-min fixed-RPE (15-Hard) cycling exercise in neutral (TMP-22 °C) and hot (HOT-37 °C) conditions, following a 60-min incongruent Stroop task (EXP) or passively watching documentary films (CON). Central and peripheral performances of the knee extensors were assessed before the cognitive task and after the exercise.Results : Although mental demand and effort were higher in EXP (P

Objectif La force et l’endurance musculaire semblent etre reduites chez le patient atteint de syndrome d’apnee obstructive du sommeil (SAOS) severe. Cette etude visait a evaluer les mecanismes neuromusculaires de la fatigue induite par l’exercice chez le patient SAOS avant et apres 8 semaines de traitement par pression positive continue (PPC). Methodes Douze patients SAOS (âge 59 ± 7 ans ; IMC 27 ± 3kg/m2 ; IAH 46 ± 13) et 11 controles apparies ont ete inclus. La force maximale volontaire (FMV), les niveaux d’activation volontaire (NAV) par stimulation du nerf femoral (FNS) et stimulation magnetique transcrânienne (TMS) et l’inhibition intracorticale ont ete mesures lors d’une tâche fatigante (TF : extensions du genou) jusqu’a epuisement. Resultats Le temps d’effort etait inferieur chez les patients SAOS compares aux controles (991 ± 461 vs 1375 ± 583s, p = 0,017). FMV (138 ± 49 vs 157 ± 49 N/m, p = 0,004), NAVFNS (86 ± 10 vs 89 ± 8 %, p = 0,022) et NAVTMS (86 ± 16 vs 91 ± 7 %, p = 0,049) etaient inferieurs chez les patients SAOS avant et pendant TF. La periode de silence (225 ± 54 vs 194 ± 47 ms, p Conclusion Cette etude demontre que les patients SAOS severes ont une dysfonction du quadriceps probablement liee a un deficit d’activation centrale et une inhibition intracorticale accrue. Un traitement de 8 semaines par PPC n’inverse pas ces alterations neuromusculaires.

INTRODUCTION: Exercise intolerance is the most predominant symptom in patients with COPD. Nevertheless, it is unclear whether walking economy and gait variability are altered in these patients. Thus, our main objective was to compare the cost of transport and gait variability as a function of speed, including the self-selected walking speed, in subjects with COPD relative to healthy subjects. METHODS: 22 subjects, 11 with COPD (FEV 1 = 45 ± 17% of predicted) and 11 age- and sex-matched healthy subjects undertook an evaluation that involved walking on a treadmill at 6 speeds (at 3.2 km/h, at a self-selected walking speed, and at 2 speeds below and 2 speeds above the self-selected walking speed) and measuring the cost of transport (the oxygen consumption normalized by mass and distance), gait variability, perceived dyspnea, and leg fatigue. RESULTS: In subjects with COPD, the cost of transport decreased with increasing walking speed, contrary to healthy subjects, who presented a minimum at the self-selected walking speed. No difference was found in cost of transport between the experimental groups at the same absolute velocity ( P = .62). In subjects with COPD, dyspnea sensation rose above the self-selected walking speed, doubling at the maximal walking velocity ( P = .03), and gait variability was higher at low speeds. CONCLUSION: Subjects with COPD choose their walking speed so as to keep the dyspnea sensation tolerable and to keep gait variability and cost of transport at an acceptable level. These outcomes suggest that interventions acting on dyspnea and gait pattern may increase patients9 self-selected walking speed and improve their quality of life

Lower muscle strength and endurance have been reported in severe obstructive sleep apnea (OSA). Increased intracortical inhibition previously reported at rest in OSA suggests central neuromuscular impairments in these patients. We hypothesized that (i) OSA patients demonstrate reduced knee extensor strength and endurance due to central impairments and (ii) continuous positive airway pressure (CPAP) treatment improves neuromuscular function in these patients.Twelve OSA patients and 11 healthy controls performed intermittent knee extensions until task failure before and after 8 wk of CPAP treatment or control period. Maximal voluntary contraction, voluntary activation and corticospinal excitability and inhibition assessed by single- and paired-pulse transcranial magnetic stimulation were measured before and during the fatiguing task.Time to exhaustion was lower in OSA (before CPAP treatment: 1008 ± 549 s; after CPAP treatment: 975 ± 378 s) compared with controls (before control period: 1476 ± 633 s; after control period: 1274 ± 506 s; P = 0.017). Obstructive sleep apnea patients had reduced maximal voluntary contraction and VATMS compared with controls throughout the fatiguing task as well as increased intracortical inhibition (all P0.05). Continuous positive airway pressure treatment did not induce any changes in neuromuscular function (P0.05 for all parameters).This study demonstrates that severe OSA patients have cortical impairments which are likely contributing to their reduced knee extensors strength and endurance. Both cortical impairments and neuromuscular function are not improved after 8 wk of CPAP treatment.

Lower muscle strength and endurance have been reported in severe obstructive sleep apnea syndrome (OSAS) patients. Increased intracortical inhibition previously reported at rest in OSAS suggests central neuromuscular impairments in these patients. This study investigated the neuromuscular mechanisms of exercise-induced fatigue in severe OSAS patients before and after an 8-week continuous positive airway pressure (CPAP) treatment. Twelve OSAS patients (age 59±7 yrs; BMI 27±3 kg·m−2; AHI 46±13 events·h−1) and 11 matched controls were included. Maximal voluntary contraction (MVC), voluntary activation (VA) levels assessed by femoral nerve electrical stimulation (FNES) and transcranial magnetic stimulation (TMS) and intracortical inhibition parameters were measured before and during a fatiguing task (FT: repeated isometric knee extensions) until exhaustion. Time to exhaustion was lower in OSAS patients compared to controls (991±461 vs 1375±583s, p=0.017). MVC (138±49 vs 157±49 N·m, p=0.004), VAFNES (86±10 vs 89±8%, p=0.022) and VATMS (86±16 vs 91±7%, p=0.049) were lower in OSAS patients before and during FT. Cortical silent period duration (quadriceps muscles: 225±54 vs 194±47ms at 35%MVC, p This study demonstrates that severe OSAS patients have reduced knee extensors strength and endurance possibly due to central activation deficit and increased intracortical inhibition. An 8-week CPAP treatment did not reverse these neuromuscular impairments.

Peripheral muscle dysfunction is an important systemic consequence of cystic fibrosis (CF) with major clinical implications, such as exercise intolerance and reduced quality of life. Evidence is now accumulating that lack of physical activity is unlikely to be the sole explanation for peripheral muscle dysfunction of patients with CF. Particularly, the demonstration of CFTR expression in both murine and human skeletal muscle suggests the potential implication of intrinsic CF-related factors. By combining data from both human and animal models, this review describes CF peripheral muscle abnormalities and critically reviews the advances in understanding the impact of the underlying mechanisms. We also describe how peripheral muscles respond to intervention in this population. Methodological concerns and directions for future research are also considered. Peripheral muscle atrophy and weakness is prevalent in patients with CF and associated with reduced aerobic and anaerobic performances. Further investigations are however needed to confirm alterations in peripheral muscle endurance and fatigability. Physical inactivity is probably the major contributor of peripheral muscle abnormalities in patients with CF with mild-to-moderate phenotypes. However, the relative influence of additional factors (e.g. inflammation, metabolic abnormalities) probably increases with disease severity making specific and individualized interventions necessary in severe patients. Exercise training is the most effective intervention to address peripheral muscle dysfunction but other strategies, such as neuromuscular electrical stimulation and nutritional or hormonal supplementation may be of interest in some patients. Investigations are needed to determine whether pharmacological interventions such as CFTR modulators are effective to address this condition. To better elucidate the etiology of peripheral muscle dysfunction in CF, future studies should combine measurements at the cellular level with indices of muscle function and monitor physical activity levels to account for its potential effects on muscle function.

Background Specific alterations in skeletal muscle related to genetic defects may be present in adults with cystic fibrosis (CF). Limb muscle dysfunction may contribute to physical impairment in CF. Aims and objectives We hypothesized that adults with CF would have altered calf muscle metabolism during exercise. Methods Fifteen adults with CF and fifteen healthy controls matched for age, gender and physical activity performed a maximal cycling test and an evaluation of calf muscle energetics by 31 P magnetic resonance spectroscopy before, during and after plantar flexions to exhaustion. Results Maximal cycling test revealed lower exercise capacities in CF (VO 2peak 2.44±0.11 vs. 3.44±0.23L·Min −1 , P =0.03). At rest, calf muscle phosphorus metabolites and pHi were similar in CF and controls ( P >0.05). Maximal power output during plantar flexions was significantly lower in CF compared to controls (7.8±1.2 vs. 6.6±2.4W; P =0.013). At exhaustion, PCr concentration was similarly reduced in both groups (CF −33±7%, controls −34±6%, P =0.44), while PCr degradation at identical absolute workload was greater in CF patients ( P =0.04). These differences disappeared when power output was normalized for differences in calf size (maximal power output: 0.10±0.02 vs. 0.10±0.03W/cm 2 ; P =0.87). Pi/PCr ratio and pHi during exercise as well as PCr recovery after exercise were similar between groups. Conclusion Similar metabolic calf muscle responses during exercise and recovery were found in CF adults and controls. Overall, muscle anabolism rather than specific metabolic dysfunction may be critical regarding muscle function in CF.

Resume Objectifs L’objectif de cette revue est d’illustrer le potentiel de la stimulation magnetique transcrânienne (TMS) dans le domaine de la physiologie de l’exercice. Elle propose tout d’abord un descriptif des differents parametres mesures par TMS et considere differents aspects methodologiques. Ensuite, par l’analyse des reponses mecaniques et electromyographiques induites par TMS, cette revue synthetise les adaptations corticospinales a l’exercice aigu fatigant et a l’exercice chronique (i.e. entrainement physique) chez le sujet sain. Actualites Au cours d’un exercice musculaire fatigant, la TMS permet classiquement de mettre en evidence le developpement d’une fatigue d’origine supraspinale (i.e. au niveau ou en amont du cortex moteur) ainsi que des modifications de l’excitabilite corticospinale et de l’inhibition intracorticale. Il existe cependant une variabilite des reponses corticospinales a la fatigue en fonction du muscle considere (e.g. membre inferieur vs superieur) et de la nature de la tâche (i.e. locale vs globale). Les etudes recentes ayant etudie les adaptations des parametres TMS a l’exercice chronique ont principalement montre une reduction de l’inhibition corticospinale apres un entrainement en force. Perspectives et projets Des etudes complementaires combinant la TMS avec d’autres techniques d’investigations neuromusculaires sont necessaires afin de dissocier plus precisement les manifestations corticales et spinales de la fatigue musculaire. Il serait egalement interessant de determiner si la composante supraspinale de la fatigue qui se developpe au cours d’un exercice prolonge peut etre reduite par un entrainement physique.

This study tested the hypothesis that during fatiguing quadriceps exercise, supraspinal fatigue develops late, is associated with both increased corticospinal excitability and inhibition and recovers quickly. Eight subjects performed 20 s contractions [15 s at 50% maximal voluntary contraction (MVC) followed by 5 s MVC] separated by a 10 s rest period until task failure. Transcranial magnetic stimulation (TMS) and electrical femoral nerve stimulation (PNS) were delivered ∼ 2 s apart during 50% MVC, during MVC and after MVC in relaxed muscle. Voluntary activation was assessed by TMS (VATMS) immediately before and after exercise and then three times over a 6 min recovery period. During exercise, MVC and twitch force evoked by PNS in relaxed muscle decreased progressively to 48 ± 8 and 36 ± 16% of control values, respectively (both P < 0.01). Significant changes in voluntary activation assessed by PNS and twitch evoked by TMS during MVC were observed during the last quarter of exercise only (from 96.4 ± 1.7 to 86 ± 13%, P = 0.03 and from 0.76 ± 0.8 to 4.9 ± 4.7% MVC, P = 0.02, from baseline to task failure, respectively). The TMS-induced silent period increased linearly during both MVC (by ∼ 79 ms) and 50% MVC (by ∼ 63 ms; both P < 0.01). Motor-evoked potential amplitude did not change during the protocol at any force levels. Both silent period and VATMS recovered within 2 min postexercise, whereas MVC and twitch force evoked by PNS in relaxed muscle recovered to only 84 ± 9 and 73 ± 17% of control values 6 min after exercise, respectively. In conclusion, high-intensity single-joint quadriceps exercise induces supraspinal fatigue near task failure, with increased intracortical inhibition and, in contrast to previous upper-limb results, unchanged corticospinal excitability. These changes recover rapidly after task failure, emphasizing the need to measure corticospinal adaptations immediately at task failure to avoid underestimation of exercise-induced corticospinal changes.

Resume Objectifs L’objectif de cette revue est d’analyser les differentes strategies susceptibles d’engendrer une amelioration significative de la tolerance a l’effort des patients atteints de mucoviscidose. Dans un premier temps, cette revue analyse l’efficacite des strategies indirectes (i.e. autres que l’exercice) pour lutter contre l’intolerance a l’effort. Ensuite, elle s’interesse a l’efficacite des differents protocoles de rehabilitation a l’effort proposes au cours de ces dernieres annees. Actualites L’intolerance a l’effort est importante dans la mucoviscidose et peut avoir des consequences directes sur le pronostic vital et la qualite de vie du patient. L’amelioration de la performance physique represente donc un enjeu majeur dans cette pathologie. Les strategies « indirectes » (e.g. supplementation vitaminique), qui ont pour objectif premier de lutter contre certains effets de la maladie, semblent avoir un effet limite sur l’intolerance a l’effort. Les benefices lies a l’exercice physique semblent en revanche suffisamment importants pour justifier l’integration de programme de rehabilitation a l’effort dans une routine clinique. Perspectives et projets Bien qu’encore tres peu documente, un programme associant entrainement aerobie et renforcement musculaire semble offrir potentiellement le plus de perspectives dans la rehabilitation a l’effort du patient mucoviscidosique. Des etudes complementaires devront confirmer cette hypothese.

This review aims to characterize fatigue-related changes in corticospinal excitability and inhibition in healthy subjects. Transcranial magnetic stimulation (TMS) has been extensively used in recent years to investigate modifications within the brain during and after fatiguing exercise. Single-pulse TMS reveals reduction in motor-evoked potentials (MEP) when measured in relaxed muscle following sustained fatiguing contractions. This modulation of corticospinal excitability observed in relaxed muscle is probably not specific to the fatigue induced by the motor task. During maximal and submaximal fatiguing contractions, voluntary activation measured by TMS decreases, suggesting the presence of supraspinal fatigue. The demonstration of supraspinal fatigue does not eliminate the possibility of spinal contribution to central fatigue. Concomitant measurement of TMS-induced MEP and cervicomedullary MEP in the contracting muscle, appropriately normalized to maximal muscle compound action potential, is necessary to determine the relative contribution of cortical and spinal mechanisms in the development of central fatigue. Recent studies comparing electromyographic (EMG) responses to paired-pulse stimuli at the cortical and subcortical levels suggest that impaired motoneuron responsiveness rather than intracortical inhibition may contribute to the development of central fatigue. This review examines the mechanical and EMG responses elicited by TMS (single- and paired-pulse) and cervicomedullary stimulation both during and after a fatiguing exercise. Particular attention is given to the muscle state and the type of fatiguing exercise when assessing and interpreting fatigue-induced changes in these parameters. Methodological concerns and future research interests are also considered.