Effects of dynamic visual feedback system on seasickness.

Motion sickness (MS) poses challenges for individuals affected, hindering their activities and travel. This study investigates the effect of a visual dynamic device, forming an artificial horizon plane, on symptoms and physiological changes induced by MS. This device consists of vertical light-emitting diodes whose illumination varies according to the boat's movements. Fifteen subjects with moderate-to-severe MS susceptibility were exposed to a seasickness simulator with and without the device. Symptoms were assessed immediately after exposure. Time spent in the simulator, heart rate, and temperature were also recorded. Symptom intensity at the end of the experience did not differ, but the time spent in the simulator was significantly longer with the device (+46%). Variations in heart rate were also observed. The device delays symptom onset and can be used as a tool against MS. Further research is needed to evaluate its effects, for example, during more prolonged exposure to MS-inducing stimuli.

Randomized controlled trial of home-based vs. hospital-based pulmonary rehabilitation in post COVID-19 patients.

BACKGROUND: Between 30% and 60% of people who have been infected with COVID-19 still had symptoms 3 months after the start of the disease. Prescribing a pulmonary rehabilitation program in rehabilitation facilities for post COVID-19 patients could help alleviate the symptoms. However, rehabilitation facilities known to provide good quality care to COVID-19 patients and all other patients, could become saturated by the rise in cases. Home-based rehabilitation is a potential solution that could be sustainable in the long term to avoid this saturation and/or a very long waiting list for patients. AIM: The aim of this study was to investigate whether home-based rehabilitation would have similar effects compared to inpatient rehabilitation on physical and respiratory variables in post COVID-19 patients. DESIGN: This is a randomized controlled trial. SETTING: Pulmonary rehabilitation facility. POPULATION: Seventeen post COVID-19 patients were randomized into two groups: inpatient pulmonary rehabilitation (IPR) or home-based pulmonary rehabilitation (HPR). METHODS: The comparison of the two rehabilitation methods relied on questionnaires, physical tests and the evaluation of several respiratory parameters. A 2-way Analysis of Variance (ANOVA) with repeated measures was performed to assess the effects of time (pre- vs. post-rehabilitation), group (IPR vs. HPR) and their interaction for all parameters. RESULTS: The main result of this study is that distance covered in the 6MWT (6MWD) shows significant improvements, between pre- and postrehabilitation program in both groups (+95 m in IPR group vs.+72 m in HPR group, P<0.001) with no significant interaction between time and group (P=0.420). CONCLUSIONS: These results suggest that home-based pulmonary rehabilitation would be as efficient as IPR to decrease physical sequelae in post COVID-19 patients. CLINICAL REHABILITATION IMPACT: It is possible to suggest both methods (home-based rehabilitation or inpatient pulmonary rehabilitation) according to the specificities of each patient and depending on hospital saturation. The choice of one or the other method should not be made to the detriment of the patient.

Perceptions of barriers to and facilitators of physical activity in adults with cystic fibrosis.

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.

Impact of Holding a Badminton Racket on Spatio-Temporal and Kinetic Parameters During Manual Wheelchair Propulsion.

Introduction: Para badminton entered the Paralympic world for the first time with the 2021 Paralympic Games in Tokyo. The particularity of this sport lies in the handling of the wheelchair and the racket simultaneously. To the best of our knowledge, and considering the youthfulness of this sport, it appears that no study has looked at the impact of the badminton racket on the kinetic and spatiotemporal parameters. Therefore, the aim of our study was to investigate the impact of the badminton racket on the amplitude of kinetic and spatiotemporal parameters of wheelchair propulsion, considered as propulsion effectiveness and risk of injury criteria. We hypothesized that holding a badminton racket while propelling the wheelchair modifies the kinetics and temporal parameters of the athlete's propulsion due to the difficulty to hold the handrim, therefore decreasing propulsion effectiveness and increasing risk of injury. Materials and Methods: For six 90-min sessions, 16 able-bodied individuals were introduced to badminton. No injuries hindered their propulsion. They had to propel with and without a racket held on the dominant side along a 20 m straight line at a constant velocity of 5 km/h. They all used the same sports wheelchair equipped with two instrumented wheels (SmartWheel). Results: Participants increased their maximal total force and force rate of rise but decreased their fraction of effective force with their dominant hand compared to the non-dominant hand when using a racket. In addition, they decreased their fraction of effective force, push time, cycle time, and push angle, and increased their maximal propulsive moment, maximal total force, and force rate of rise when comparing the same dominant hand with and without the racket. Discussion: Using a badminton racket modifies the athlete's force application in a way that is generally related to lower propulsion effectiveness and a higher risk for injury. Indeed, it seems that propulsion with a racket prevents from correctly grabbing the handrim.

Sprint performance and force application of tennis players during manual wheelchair propulsion with and without holding a tennis racket.

The objective of this exploratory research is to study the impact of holding a tennis racket while propelling a wheelchair on kinetic and temporal parameters in a field-based environment. 13 experienced wheelchair tennis players with disabilities (36.1 ± 8.2 years, 76.8 ± 15.3 kg, 174.8 ± 17.1 cm) classified between 30/8 and first series performed two 20 m sprints in a straight line, on a tennis court: one while holding a tennis racket and the second without a tennis racket. They used their own sports wheelchair. Potential participants were excluded if they had injuries or pain that impaired propulsion. Maximal total force, maximal propulsive moment, rate of rise, maximal power output, push and cycle times and maximal velocity were measured. Sprinting while holding a tennis racket increased the cycle time by 0,051 s and push time by 0,011s. Sprinting while holding a tennis racket decreased the maximal propulsive moment, maximal power output, rate of rise and maximal velocity during propulsion by 6.713 N/m, 151.108 W, 672.500 N/s and 0.429 m/s, respectively. Our results suggest that the biomechanical changes observed associated with racket propulsion are generally in a direction that would be beneficial for the risk of injury. But sprinting holding a racket seems to decrease players propulsion performance. Working on forward accelerations with a tennis racket would be a line of work for coaches.

Development and validation of the Cystic Fibrosis Decisional Balance for Physical Activity scale (CF-DB-PA).

BACKGROUND: People with cystic fibrosis (pwCF) derive several physiological and psychological benefits from regular physical activity (PA), but the practice is lower than recommended. Knowledge about the facilitators of and barriers to PA at the individual level is important to act positively on PA behaviors. This study validated the Cystic Fibrosis Decisional Balance for Physical Activity scale (CF-DB-PA) for adults with CF. METHODS: French adults with CF were recruited in several specialist centres in France. The CF-DB-PA scale was validated following a quantitative study protocol comprising four stages: (1) tests of the clarity and relevance of a preliminary 44-item version and reduction analysis, (2) confirmatory factor analysis and tests of dimensionality through equation modelling analysis, (3) tests of reliability with Cronbach alphas for the internal consistency and a test-retest with a 2-to-3 week interval for temporal stability, and 4) tests of construct validity with Spearman correlations to measure the associations between each subscale and the theoretically related constructs (i.e., quality of life, PA and exercise tolerance). RESULTS: A total of 201 French adults with CF participated in the validation study. The CF-DB-PA comprises 23 items divided into two factors: facilitators of and barriers to PA. Each factor is divided into three subscales: physical, psychological and environmental. The factors (facilitators and barriers) can be used independently or combined as a whole. A general score of decisional balance for PA can also be calculated. The bi-factor model presented satisfactory adjustment indexes: χ2 (194) = 362.33; p < .001; TLI = .87; CFI = .90; RMSEA = .067. The scale showed satisfactory internal consistency (Cronbach's α = .77). The test-retest reliability was not significant for either subscale, indicating stability over time. The facilitators subscale correlated significantly with the self-reported score of PA (r = .33, p < .01) and quality of life (r = .24, p < .05). The barriers subscale correlated significantly with the self-reported scores of PA (r = - .42, p > .01), quality of life (r = - .44, p < .01), exercise tolerance (r = - .34, p < .01) and spirometry tests (r = - .30, p < .05). CONCLUSIONS: The CF-DB-PA is a reliable and valid questionnaire assessing the decisional balance for PA, the facilitators of and the barriers to PA for adults with CF in French-speaking samples.

Effects of Nonstationarity on Muscle Force Signals Regularity During a Fatiguing Motor Task.

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 ), 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 nonstationary 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 Sample Entropy with neuromuscular fatigue.

Influence of cognitive load on the dynamics of neurophysiological adjustments during fatiguing exercise.

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.

Interactions between perceived exertion and thermal perception in the heat in endurance athletes.

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 < 0.05), no effect of prior cognitive task was observed on subjective feelings of mental fatigue or decline in power output at a fixed RPE. Average exercise intensity was lower in HOT than TMP (3.14 ±â€¯0.09 W⋅kg-1vs. 3.42 ±â€¯0.10 W⋅kg-1 respectively, P < 0.05). Skin temperature and warmth sensations were higher in HOT throughout the exercise (P < 0.05) but not thermal comfort. Central and peripheral parameters were not affected more in HOT than in TMP. CONCLUSION: Although the effects of combined stressors on the distortion of perceived exertion could not be verified, the greater decline in power output recorded in HOT than TMP suggest a high contribution of both perceptual and cardiovascular responses in the regulation of work rate when the subject is in mild hyperthermia.

Overall and differentiated sensory responses to cardiopulmonary exercise test in patients with cystic fibrosis: kinetics and ability to predict peak oxygen uptake.

PURPOSE: We evaluated the validity of predicting peak oxygen uptake ([Formula: see text]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. METHODS: 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 [Formula: see text]O2 and RPE ≤ 15 were extrapolated to maximal theoretical RPE (i.e. RPE18 and RPE19) to predict [Formula: see text]O2peak. Agreements between measured and all predicted [Formula: see text]O2peak were tested using Bland-Altman Plots, for the whole group and for subjects presenting significant exercise intolerance (n = 24). RESULTS: Leg, chest and overall RPE increased similarly with exercise intensity. No differences were found between predicted [Formula: see text]O2peak and measured [Formula: see text]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. CONCLUSIONS: Submaximal RPE scores obtained during CPET can provide acceptable estimate of [Formula: see text]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.

Effects of Combined Vigorous Interval Training Program and Diet on Body Composition, Physical Fitness, and Physical Self-Perceptions Among Obese Adolescent Boys and Girls.

PURPOSE: This study examined the effects of a five-week intervention combining vigorous interval training (VIT) with diet among twenty-four obese adolescents. Fourteen girls and ten boys (aged 14-15) schooled in a pediatric rehabilitation center participated. METHODS: The VIT intensity was targeted and remained above 80% of maximal heart rate (HR) and over six kilocalories per minute. Pre- and postintervention measures were body composition (BMI, weight, body fat percentage), physical self-perceptions (PSP), physical fitness (6-min walking distance and work) and its associated physiological responses (HRpeak and blood lactate concentration). A series of two-way analyses of variance or covariance controlling for weight loss were used to examine the changes. RESULTS: Significant improvements were found in body composition, physical fitness and PSP (endurance, activity level, sport competence, global physical self-concept and appearance). In addition, boys presented higher levels of perceived strength and global physical self-concept than girls. Finally, there was a significant increase in perceived endurance, sport competence, and global physical self-concept in girls only. CONCLUSION: This five-week VIT program combined with diet represents an effective means for improving body composition, physical fitness, and PSP in obese adolescents, the effects on PSP being larger among girls.

The 1-Minute Sit-to-Stand Test in Adults With Cystic Fibrosis: Correlations With Cardiopulmonary Exercise Test, 6-Minute Walk Test, and Quadriceps Strength.

BACKGROUND: Exercise testing is part of the regular assessment of patients with cystic fibrosis (CF). We aimed to evaluate (1) the convergent validity of the 1-min sit-to-stand (STS) test in CF by investigating its relationships with peak oxygen uptake (peak V̇O2 ), quadriceps strength, and quality of life and (2) to compare these associations with those of the 6-min walk test (6MWT). METHODS: Twenty-five adults with CF (FEV1 = 59 ± 24%) performed the STS test, the 6MWT, quadriceps strength assessment, and cardiopulmonary exercise test (CPET). Physical activity level, quality of life, and self-esteem were assessed by questionnaires. RESULTS: STS repetitions, 6-min walk distance, quadriceps strength, and peak V̇O2 were, respectively, 71 ± 12, 90 ± 10, 93 ± 29, and 62 ± 16% of predicted. The STS test had moderate associations with peak V̇O2 (r = 0.56, P = .004), quadriceps strength (r = 0.52, P = .008), and some questionnaire items (eg, perceived physical strength, r = 0.67, P < .001) only when repetitions were expressed as a product of body weight. Overall, these associations were weaker than those obtained from 6-min walk distance × weight. Oxygen desaturation during the STS test was strongly associated with oxygen desaturation during CPET (r = 0.80, P < .001). Peak heart rate was lower during the STS test as compared with CPET (P < .001) and the 6MWT (P = .009). CONCLUSIONS: The STS test cannot be used as a replacement for CPET to accurately assess peak exercise capacity in CF. The STS test may have utility in detecting patients with CF who may exhibit a high level of oxygen desaturation during heavy exercise. Further studies should identify the factors contributing to STS performance to confirm the potential interest of STS repetitions × body weight outcome as a useful submaximal exercise parameter in CF.

Psycho-Physiological Responses of Obese Adolescents to an Intermittent Run Test Compared with a 20-M Shuttle Run.

Among the running field tests that measure aerobic fitness indirectly, the 20-m shuttle run test is the one most commonly used among obese youth. However, this back and forth running test induces premature cessation of exercise in this population. The present study aimed to examine the psycho-physiological responses of obese adolescents to an intermittent (15-15) progressive and maximal run test as compared with a continuous shuttle run test. Eleven obese adolescents (age: 14-15 years; BMI = 34.01 ± 5.30 kg·m-2) performed both tests. A two-way ANOVA examined the main effects of the running test, participant's sex, and their interaction on maximal aerobic performance (net exercise duration and final velocity), physiological values (heart rate, pulmonary oxygen uptake, respiratory exchange ratio and blood lactate concentration) and psychological responses (rating of perceived exertion, and physical self-perceptions). Oxygen uptake and heart-rate values at 9 km·h-1 were also compared. Compared with a 20-m shuttle run, the 15-15 test induced lower pulmonary oxygen uptake values at 9 km/h (28.3 ± 2.7 vs. 35.4 ± 2.7 ml·min-1·kg-1) and finished with higher maximal velocity and net exercise duration (566 ± 156 vs. 346 ± 156 s, p < 0.001), with no inter-test physiological difference. The 15-15 test also resulted in higher ratings of perceived exertion (16.0 ± 1.2 vs. 12.7 ± 1.6, p < 0.001) and improved perceived physical condition compared with the 20-m shuttle run (+1.4 ± 1.4 vs. +0.2 ± 1.0, p < 0.05). Both tests induced a maximal aerobic power of obese adolescents, but the 15-15 test provided a more progressive speed increment and longer exercise duration. The 15-15 test also elicited a significant improvement of perceived physical condition. In conclusion the 15-15 test can be considered a relevant field test for assessing the aerobic fitness of obese adolescents.

Physiological Responses of the Modified Shuttle Test in Adults With Cystic Fibrosis.

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.

Skeletal muscle contractility and fatigability in adults with cystic fibrosis.

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: Some indexes of muscle contractility tended to be reduced at rest in CF compared to controls (e.g., mechanical response to doublets stimulation 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>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.

Effects of Ramadan intermittent fasting on middle-distance running performance in well-trained runners.

OBJECTIVE: To assess whether Ramadan intermittent fasting (RIF) affects 5000-m running performance and physiological parameters classically associated with middle-distance performance. DESIGN: Two experimental groups (Ramadan fasting, n = 9, vs control, n = 9) participated in 2 experimental sessions, one before RIF and the other at the last week of fasting. SETTING: For each session, subjects completed 4 tests in the same order: a maximal running test, a maximal voluntary contraction (MVC) of knee extensor, 2 rectangular submaximal exercises on treadmill for 6 minutes at an intensity corresponding to the first ventilatory threshold (VT1), and a running performance test (5000 m). PARTICIPANTS: Eighteen, well-trained, middle-distance runners. MAIN OUTCOME MEASURES: Maximal oxygen consumption, MVC, running performance, running efficiency, submaximal VO(2) kinetics parameters (VO(2), VO(2)b, time constant τ, and amplitude A1) and anthropometric parameters were recorded or calculated. RESULTS: At the end of Ramadan fasting, a decrease in MVC was observed (-3.2%; P < 0.00001; η, 0.80), associated with an increase in the time constant of oxygen kinetics (+51%; P < 0.00007; η, 0.72) and a decrease in performance (-5%; P < 0.0007; η, 0.51). No effect was observed on running efficiency or maximal aerobic power. CONCLUSIONS: These results suggest that Ramadan changes in muscular performance and oxygen kinetics could affect performance during middle-distance events and need to be considered to choose training protocols during RIF.

Use of the peak heart rate reached during six-minute walk test to predict individualized training intensity in patients with cystic fibrosis: validity and reliability.

OBJECTIVE: To determine whether the peak heart rate reached during a six-minute walk test (HR(6peak)) can be used to predict the heart rate determined at the gas exchange threshold (HR(GET)) during a maximal cardiopulmonary exercise test (CPET) in patients with cystic fibrosis (CF). To assess the test-retest reliability of HR(6peak). DESIGN: Case-control and reliability study. SETTING: CF unit. PARTICIPANTS: Adults with CF (n=23) and age-matched sedentary subjects (control group, n=17). INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Six-minute walk test, HR(6peak), CPET, and HR(GET). RESULTS: HR(GET) and HR(6peak) were not significantly different and were highly correlated in both groups (CF, r=.91, P<.01; controls, r=.81, P<.01). The mean differences (HR(6peak)-HR(GET)) for patients with CF and control subjects were, respectively, -0.9 beats.min(-1) (bpm) and -0.1 bpm, with neither significantly different from 0. The limits of agreements were +/-11 bpm and +/-18 bpm, respectively. HR(6peak) demonstrated excellent relative reliability (intraclass correlation coefficient=.93) and was associated with low variability (standard error of measurement=4.9 bpm) in patients with CF. CONCLUSIONS: HR(6peak) is valid and demonstrates satisfactory test-retest reliability in patients with CF. These results might suggest the use of HR(6peak) as a simple alternative method to individualize exercise prescriptions in this population. Further studies are needed in a larger cohort of patients to confirm these preliminary findings.

Does prior 1500-m swimming affect cycling energy expenditure in well-trained triathletes?

The purpose of this study was to determine the effects of a 1,500-m swim on energy expenditure during a subsequent cycle task. Eight well-trained male triathletes (age 26.0 +/- 5.0 yrs; height 179.6 +/- 4.5 cm; mass 71.3 +/- 5.8 kg; VO(2)max 71.9 +/- 7.8 ml.kg(-1).min(-1)) underwent two testing sessions in counterbalanced order. The sessions consisted of a 30-min ride on the cycle ergometer at 75% of maximal aerobic power (MAP), and at a pedaling frequency of 95 rev.min(-1), preceded either by a 1,500-m swim at 1.20 m.s(-1) (SC trial) or by a cycling warm-up at 30% of MAP (C trial). Respiratory and metabolic data were collected between the 3rd and the 5th min, and between the 28th and 30th min of cycling. The main results indicated a significantly lower gross efficiency (13.0%) and significantly higher blood lactate concentration (56.4%), VO(2) (5.0%), HR (9.3%), VE (15.7%), and RF (19.9%) in the SC compared to the C trial after 5 min, p < 0.05. After 30 min, only VE (7.9%) and blood lactate concentration (43.9%) were significantly higher in the SC compared to the C trial, p < 0.05. These results confirm the increase in energy cost previously observed during sprint-distance triathlons and point to the importance of the relative intensity of swimming on energy demand during subsequent cycling.

Effects of long duration exercise on cognitive function, blood glucose, and counterregulatory hormones in male cyclists.

Electrocortical effects of long duration exercise on cognitive function were investigated by analyzing P300 amplitude and latency changes during a 3-h cycling exercise. P300 components were measured in 12 well-trained cyclists and blood glucose, cortisol, insulin, glycerol, and free fatty acids (FFAs) epinephrine and norepinephrine were analyzed. Results indicated that P300 components were affected by exercise with a temporary increase in amplitude between the 1st and the 2nd hour and an increase in latency after 2 h of exercise concomitant with some hormonal changes, including an increase in cortisol and epinephrine and a decrease in blood glucose. These findings suggest a combined effect of arousal and central fatigue on electrocortical indices of cognitive function during acute physical exercise.

[Energy cost of running during a specific transition in duathlon]. / Coût énergétique de la course à pied lors de l'enchaînement spécifique d'un duathlon.

The aim of the present study was to investigate the variability of the energy cost of running (Cr) during a simulated duathlon performed in outdoor conditions by elite duathletes. This duathlon consisted of 5 km of running, 30 km of cycling, and 5 km of running. The main result was the lack of significant difference in Cr between the two running bouts (210 +/- 10 mL d'O2.km-1.kg-1 vs. 217 +/- 10 mL d'O2.km-1.kg-1). This result is different from those observed during a triathlon, where an increase of energy cost of running bout has been reported. Furthermore, during a short-distance duathlon performed by well-trained subjects, none of the physiological (ventilation alteration, metabolic changes, or dehydration) or biomechanical factors that are classically evoked in triathlon research to explain Cr variability seem to be affected by the run-cycle-run transition. These results seem to minimize the negative effect of the cycle-to-run transition during a short-duration event in well-trained subjects.