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.

Paraspinal muscle oxygenation and mechanical efficiency are reduced in individuals with chronic low back pain

This study aimed to compare the systemic and local metabolic responses during a 5-min trunk extension exercise in individuals with chronic low back pain (CLBP) and in healthy individuals. Thirteen active participants with CLBP paired with 13 healthy participants performed a standardised 5-min trunk extension exercise on an isokinetic dynamometer set in continuous passive motion mode. During exercise, we used near-infrared spectroscopy to measure tissue oxygenation (TOI) and total haemoglobin-myoglobin (THb). We used a gas exchange analyser to measure breath-by-breath oxygen consumption (V̇O2) and carbon dioxide produced (V̇CO2). We also calculated mechanical efficiency. We assessed the intensity of low back pain sensation before and after exercise by using a visual analogue scale. In participants with CLBP, low back pain increased following exercise (+ 1.5 units; p < 0.001) and THb decreased during exercise (- 4.0 units; p = 0.043). Paraspinal muscle oxygenation (65.0 and 71.0%, respectively; p = 0.009) and mechanical efficiency (4.7 and 5.3%, respectively; p = 0.034) were both lower in participants with CLBP compared with healthy participants. The increase in pain sensation was related to the decrease in tissue oxygenation (R2 = - 0.420; p = 0.036). Decreases in total haemoglobin-myoglobin and mechanical efficiency could involve fatigability in exercise-soliciting paraspinal muscles and, therefore, exacerbate inabilities in daily life. Given the positive correlation between tissue oxygenation and exercise-induced pain exacerbation, muscle oxygenation may be related to persisting and crippling low back pain.

Physiological Responses to Supramaximal Running Exercise with End-Expiratory Breath Holding up to the Breaking Point

This study aimed to assess the physiological responses to repeated running exercise performed at supramaximal intensity and with end-expiratory breath holding (EEBH) up to the breaking point. Eight male runners participated in two running testing sessions on a motorized treadmill. In the first session, participants performed two sets of 8 repetitions at 125% of maximal aerobic velocity and with maximum EEBH. Each repetition started at the onset of EEBH and ended at its release. In the second session, participants replicated the same procedure, but with unrestricted breathing (URB). The change in cerebral and muscle oxygenation (Δ[Hbdiff]), total haemoglobin concentration (Δ[THb]) and muscle reoxygenation were continuously assessed. End-tidal oxygen (PETO2) and carbon dioxide pressure (PETCO2), arterial oxygen saturation (SpO2) and heart rate (HR) were also measured throughout exercise.On average, EEBH was maintained for 10.1 ± 1 s. At the breaking point of EEBH, PETO2 decreased to 54.1 ± 8 mmHg, whereas PETCO2 increased to 74.8 ± 3.1 mmHg. At the end of repetitions, SpO2 (nadir values 74.9 ± 5.0 vs. 95.7 ± 0.8%) and HR were lower with EEBH than with URB. Cerebral and muscle Δ[Hbdiff] were also lower with EEBH, whereas this condition induced higher cerebral and muscle Δ[THb] and greater muscle reoxygenation. This study showed that performing repeated bouts of supramaximal running exercises with EEBH up to the breaking point induced a fall in arterial, cerebral and muscle oxygenation compared with the URB condition. These phenomena were accompanied by increases in regional blood volume likely resulting from compensatory vasodilation to preserve oxygen delivery to the brain and muscles.

Effect of acute heat exposure on the determination of critical power and W' in women and men

The goal of this study was to investigate to what extent acute heat exposure would affect the parameters of the power-duration relationship, i.e. CP and W', using multiple constant workload tests to task failure, in women and men. Twenty four young physically active participants (12 men, 12 women) performed 3-5 constant load tests to determine CP and W', both in temperate (TEMP; 18°C) and hot (HOT; 36°C) environmental conditions. A repeated-measures ANOVA was executed to find differences between TEMP and HOT, and between women and men. In HOT, CP was reduced by 6.5% (227 ± 50 vs. 212 ± 47 W), while W' increased 12.4% (16.4 ± 4.4 vs. 18.5 ± 5.6 kJ). No significant two-way sex × temperature interactions were observed, indicating that the environmental conditions did not have a different effect in men compared with women. The intersection of the average curvatures in TEMP and HOT occurred at 137 s and 280 W in women, and 153 s and 397 W in men. Acute heat exposure had an impact on the parameters CP and W', i.e. CP decreased whereas W' increased. The increase in W' might be a consequence of the mathematical modelling for the used test methodology, rather than a physiological accurate value of W' in HOT. No differences induced by heat exposure were observed between women and men.

Critical power, W' and W' reconstitution in women and men

PURPOSE

The aim of this study was to compare critical power (CP) and work capacity W', and W' reconstitution (W'REC) following repeated maximal exercise between women and men.

METHODS

Twelve women ([Formula: see text]O2PEAK: 2.53 ± 0.37 L·min-1) and 12 men ([Formula: see text]O2PEAK: 4.26 ± 0.30 L·min-1) performed a minimum of 3 constant workload tests, to determine CP and W', and 1 maximal exercise repetition test with three work bouts (WB) to failure, to quantify W'REC during 2 recovery periods, i.e., W'REC1 and W'REC2. An independent samples t test was used to compare CP and W' values between women and men, and a repeated-measures ANOVA was used to compare W'REC as fraction of W' expended during the first WB, absolute W'REC, and normalized to lean body mass (LBM).

RESULTS

CP normalized to LBM was not different between women and men, respectively, 3.7 ± 0.5 vs. 4.1 ± 0.4 W·kgLBM-1, while W' normalized to LBM was lower in women 256 ± 29 vs. 305 ± 45 J·kgLBM-1. Fractional W'REC1 was higher in women than in men, respectively, 74.0 ± 12.0% vs. 56.8 ± 9.5%. Women reconstituted less W' than men in absolute terms (8.7 ± 1.2 vs. 10.9 ± 2.0 kJ) during W'REC1, while normalized to LBM no difference was observed between women and men (174 ± 23 vs. 167 ± 31 J·kgLBM-1). W'REC2 was lower than W'REC1 both in women and men.

CONCLUSION

Sex differences in W'REC (absolute women < men; fractional women > men) are eliminated when LBM is accounted for. Prediction models of W'REC might benefit from including LBM as a biological variable in the equation. This study confirms the occurrence of a slowing of W'REC during repeated maximal exercise.

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.

The effect of acute heat exposure on the determination of exercise thresholds from ramp and step incremental exercise

PURPOSE

The aim of this study was to examine how respiratory (RT) and lactate thresholds (LT) are affected by acute heat exposure in the two most commonly used incremental exercise test protocols (RAMP and STEP) for functional evaluation of aerobic fitness, exercise prescription and monitoring training intensities.

METHODS

Eleven physically active male participants performed four incremental exercise tests, two RAMP (30 W·min^-1) and two STEP (40 W·3 min^-1), both in 18 °C (TEMP) and 36 °C (HOT) with 40% relative humidity to determine 2 RT and 16 LT, respectively. Distinction was made within LT, taking into account the individual lactate kinetics (LT_IND) and fixed value lactate concentrations (LT_FIX).

RESULTS

A decrease in mean power output (PO) was observed in HOT at LT (-6.2 ± 1.9%), more specific LT_IND (-5.4 ± 1.4%) and LT_FIX (-7.5 ± 2.4%), compared to TEMP, however not at RT (-1.0 ± 2.7%). The individual PO difference in HOT compared to TEMP over all threshold methods ranged from -53 W to +26 W. Mean heart rate (HR) did not differ in LT, while it was increased at RT in HOT (+10 ± 8 bpm).

CONCLUSION

This study showed that exercise thresholds were affected when ambient air temperature was increased. However, a considerable degree of variability in the sensitivity of the different threshold concepts to acute heat exposure was found and a large individual variation was noticed. Test design and procedures should be taken into account when interpreting exercise test outcomes.

Respiratory function in uncomplicated type 1 diabetes: Blunted during exercise even though normal at rest!

AIMS

Type 1 diabetes is associated with a substantially increased risk of impaired lung function, which may impair aerobic fitness. We therefore aimed to examine the ventilatory response during maximal exercise and the pulmonary diffusion capacity function at rest in individuals with uncomplicated type 1 diabetes.

METHODS

In all, 17 adults with type 1 diabetes free from micro-macrovascular complications (glycated haemoglobin: 8.0 ± 1.3%), and 17 non-diabetic adults, carefully matched to the type 1 diabetes group according to gender, age, level of physical activity and body composition, participated in our study. Lung function was assessed by spirometry and measurements of the combined diffusing capacity for nitric oxide (DLNO) and carbon monoxide (DLCO) at rest. Subjects performed a maximal exercise test during which the respiratory parameters were measured.

RESULTS

At rest, DLCO (30.4 ± 6.1 ml min^-1  mmHg^-1 vs. 31.4 ± 5.7 ml min^-1 mmHg^-1 , respectively, p = 0.2), its determinants Dm (membrane diffusion capacity) and Vc (pulmonary capillary volume) were comparable among type 1 diabetes and control groups, respectively. Nevertheless, spirometry parameters (forced vital capacity = 4.9 ± 1.0 L vs. 5.5 ± 1.0 L, p < 0.05; forced expiratory volume 1 = 4.0 ± 0.7 L vs. 4.3 ± 0.7 L, p < 0.05) were lower in individuals with type 1 diabetes, although in the predicted normal range. During exercise, ventilatory response to exercise was different between the two groups: tidal volume was lower in type 1 diabetes vs. individuals without diabetes (p < 0.05). Type 1 diabetes showed a reduced VO_2max (34.7 ± 6.8 vs. 37.9 ± 6.3, respectively, p = 0.04) in comparison to healthy subjects.

CONCLUSIONS

Individuals with uncomplicated type 1 diabetes display normal alveolar-capillary diffusion capacity and at rest, while their forced vital capacity, tidal volumes and VO₂ are reduced during maximal exercise.

What are the most important symptoms to assess in hypermobile Ehlers-Danlos syndrome? A questionnaire study based on the Delphi technique

PURPOSE

This study aims to determine from questionnaires, submitted to patients with Ehlers-Danlos syndrome hypermobile type (hEDS), what symptoms they perceive as having the most impact on their well-being and, according to them, what symptoms should be assessed.

MATERIALS AND METHODS

Three rounds of online questionnaires were conducted following the Delphi method. The first round allowed us to obtain the most important symptoms to assess according to the patients. The second and third round aimed at ranking the categories according to their order of importance. Establishment of a consensus was evaluated using Kendall's coefficient of concordance.

RESULTS

A total of 118 responses were analyzed for the first round and 87 for the second and the third round. Ten categories were extracted from the first round. Ranking of the 10 categories in the second round did not reach consensus (W = 0.33, p < 0.001) nor did the four most important categories in the third round (W = 0.43, p < 0.001). However, three categories stand out from ranking: "pain", "fatigue and sleep disorders", and "musculoskeletal disorders".

CONCLUSIONS

These categories seem to be the most important to assess in patients with hEDS, despite the lack of consensus on this ranking.Implications for rehabilitationPain, fatigue and sleep disorders, and musculoskeletal disorders should be given high consideration in the assessment of patients with hypermobile Ehlers-Danlos syndrome (EDS).The high phenotypic variability in the hypermobile EDS requires individualized assessment for each patient and a multidisciplinary approach.

Quadriceps physiological response during the 1-min sit-to-stand test in people with severe COPD and healthy controls

We compared quadriceps oxygenation and surface electromyography (sEMG) responses during the 1-min sit-to-stand (1STS) in 14 people with severe COPD and 12 controls, in whom cardiorespiratory response, near-infrared spectroscopy signals (oxy [Hb-Mb], deoxy [Hb-Mb], total [Hb-Mb], and SmO₂) and sEMG signals of the quadriceps were recorded. Time duration of each sit-to-stand cycle and the total work performed during the 1STS were measured. The quadriceps oxygenation parameters were normalized by reporting their values according to the total work during 1STS. The rate of sit-to-stand maneuvers decelerated in people with COPD leading to smaller total work compared with controls. The pattern of quadriceps oxygenation response during 1STS was similar between groups. However, in COPD, the recovery after 1STS was characterized by larger overshoots in oxy [Hb-Mb], total [Hb-Mb], and SmO₂. When corrected for the cumulative total work, the increase in muscle O₂ extraction (deoxy [Hb-Mb]) during the first 30 s of recovery was greater in people with COPD compared to controls. Quadriceps sEMG changes suggestive of a fatiguing contraction pattern was observed only in people with COPD. All together, these results highlighted physiological misadaptation of people with severe COPD to the 1STS.

Changes in pulmonary function after long-duration adventure racing in adolescent athletes

The present study investigated the acute effects of a mixed-modality, long-duration adventure race on pulmonary function in adolescent athletes. Twenty male adolescents aged 14 to 17 years volunteered to participate in a wilderness adventure race of 68.5-km. Expiratory function was evaluated before, immediately after, and 24 h after race completion. Measurements included forced vital capacity (FVC), forced expiratory volume in 1 s (FEV1) and peak expiratory flow (PEF). Maximal inspiratory and expiratory mouth static pressures (MIP and MEP, respectively) were also measured using a portable hand-held mouth pressure meter across the same time points. The mean completion time of the race was 05:38 ± 00:20 hours. A significant post-race decrease in FVC was observed immediately after the race (-5.2%, p = 0.01). However, no significant changes were observed for FEV1, PEF and the FEV1/FVC and FEV1/PEF ratios. In addition, estimates of respiratory muscle strength (MIP and MEP) were unaffected by the race. The long-duration adventure race induced no marked reduction in expiratory pulmonary function and this response was associated with no apparent respiratory muscle fatigue. Therefore, the pulmonary system of trained adolescent athletes was sufficiently robust to sustain the mixed-modality, long-duration adventure race of ∽5-6 h.

Home-based Pulmonary Rehabilitation is Effective in Frail COPD Patients with Chronic Respiratory Failure

Daily life disability and vulnerability is often reported in patients with chronic obstructive pulmonary disease (COPD) and chronic respiratory failure. Although pulmonary rehabilitation is feasible in this population, its benefits on functional status and physical frailty is uncertain. This study aimed to evaluate the short- and medium-term effectiveness of a home-based pulmonary rehabilitation program in COPD patients with chronic respiratory failure. We also evaluate the impact of frailty status on the efficacy of the intervention. Forty-seven participants underwent an 8-week home-based program. Functional capacity, physical frailty (Fried criteria), exercise tolerance, health-related quality of life, general fatigue, and anxiety and depressive symptoms were assessed at baseline (M0), and at 8 weeks (M2) and 8 months (M8) following study inclusion. For the group as a whole, functional capacity, physical frailty, health-related quality of life and fatigue scores were all improved at M2 and M8 (p<0.05), while exercise tolerance and depressive symptoms were only improved at M8 (p<0.01). However, when the group was divided according to frailty status, only the frails patients had improved health related quality of life, general fatigue, and anxiety and depressive symptoms scores after PR (p<0.05). In COPD patients with chronic respiratory failure, home-based pulmonary rehabilitation may be effective for improving functional capacity, physical frailty and health related quality of life at short- and medium-term. Physical frailty was not a barrier for benefiting from the intervention, and almost 80% of the patients who were frail prior to the program improved their frailty status after pulmonary rehabilitation.

Specific Contribution of Quadriceps Muscle Strength, Endurance, and Power to Functional Exercise Capacity in People With Chronic Obstructive Pulmonary Disease: A Multicenter Study

OBJECTIVE

Various functional muscle properties affect different aspects of functional exercise capacity in people with chronic obstructive pulmonary disease (COPD). The purpose of this study was to investigate the contribution of quadriceps muscle strength, endurance, and power to 6-Minute Walking Distance (6MWD) and 1-minute sit-to-stand test (1STS) performance in people with COPD.

METHODS

The study was a prospective, multicenter, cross-sectional study. Anthropometrics, Medical Research Council dyspnea scale, lung function, 6MWD, and 1STS number of repetitions were assessed. Isometric quadriceps strength and endurance, isotonic quadriceps endurance, isokinetic quadriceps strength, and power were assessed on a computerized dynamometer while functional quadriceps power was determined during 5 sit-to-stand repetitions. Univariate and multivariate analyses were performed to determine the contribution of functional muscle properties to the 6MWD and the 1STS number of repetitions.

RESULTS

The study included 70 people with COPD (mean % predicted forced expiratory volume in 1 second = 58.9 [SD = 18.2]). The 6MWD correlated with each functional muscle property except the isometric quadriceps endurance. The number of repetitions during the 1STS correlated with each functional muscle property except isometric measurements. Multivariate models explained 60% and 39% of the variance in the 6MWD and 1STS number of repetitions, respectively, with quadriceps power determined during 5 sit-to-stand repetitions being the muscle functional property with the strongest contribution to the models.

CONCLUSION

Except for isometric endurance, quadriceps strength, endurance, and power were associated with functional exercise capacity in people with moderate COPD. Among these functional muscle properties, muscle power contributed the most to the 6MWD and 1STS number of repetitions, suggesting that muscle power is more relevant to functional exercise capacity than muscle strength or endurance in people with COPD.

IMPACT

Understanding the individual contribution of muscle properties to functional status is important to designing interventions. This study provides the guidance that muscle power may be more important to functional exercise capacity than muscle strength or endurance in people with COPD.

Physical Frailty in COPD Patients with Chronic Respiratory Failure

Background

The prevalence of physical frailty and its clinical characteristics in advanced chronic obstructive pulmonary disease (COPD) is unknown, as well as the usefulness of functional capacity tests to screen for physical frailty. The aim of the study was to evaluate the proportion and clinical portrait of COPD patients with chronic respiratory failure exhibiting physical frailty at the time of referral to home-based pulmonary rehabilitation. We also evaluate the usefulness of the short physical performance battery (SPPB) and timed-up and go (TUG) as potential screening tools for physical frailty. Finally, we evaluated the specific contribution of gait speed to the frailty Fried total score.

Methods

This was a prospective observational study in which physical frailty was defined using Fried criteria (body mass loss, exhaustion, low physical activity, slower walking and weakness). Clinical portrait was documented from daily physical activity, exercise tolerance, functional capacity, anxiety and depressive symptoms, health-related quality of life, and fatigue scores. The ability of the SPPB and TUG to predict physical frailty was investigated using receiver operating characteristic curves. Contribution of each Fried criteria was evaluated with a principal component analysis (PCA).

Results

Amongst the 44 included participants (FEV₁, 33 ± 13% of predicted), 19 were physically frail. Frail individuals had lower daily steps number, exercise tolerance and functional capacity, and higher fatigue, anxiety, and depressive symptom scores (p<0.05) compared to non-frail individuals. SPPB and TUG did not have an acceptable detection accuracy for screening physical frailty. PCA indicated that gait speed was the main contributor to the Fried total score of physical frailty.

Conclusion

Physical frailty affects a large proportion of COPD patients with chronic respiratory failure starting a home-based intervention and was associated with worse clinical status. Although the present results need to be confirmed by adequately powered studies, gait speed seems to have the potential to become a simple screening tool for physical frailty in this population.

Influence of grade of obesity on the achievement of VO2max using an incremental treadmill test in youths

The purpose of this study was to analyze the influence of grade of obesity on the probability of achieving a VO2 plateau and threshold secondary criteria for verifying VO2max during a treadmill walk test in youths with obesity. Therefore, 72 youths with obesity (aged 8-16) performed an incremental treadmill walk test to exhaustion during which oxygen uptake (VO2), minute ventilation (VE), heart rate (HR) and rating of perceived exertion were continuously measured. HR corresponding to a "hard" level of perceived exertion was reported and expressed as a percentage of the predicted HRmax. The rate of achievement of criteria for validation VO2max (VO2 plateau; HR>95% theoretical HRmax; RER>1.0; rating of perceived exertion ≥ "hard") was compared between participants with grade I and grade II obesity. 37% of the participants achieved a VO2 plateau and 23% achieved both an HR>95% and RER >1.0. Youths with grade II obesity had lower minute ventilation (p<0.01) tended to be more likely to reach an HR>95% (OR = 0.33; P=0.06) and a "hard" rating of perceived exertion than grade I (OR = 4.5; P=0.07). However, there was no influence of grade of obesity on the achievement of VO2 plateau, and RER>1.0.

Pro-Oxidant/Antioxidant Balance during a Prolonged Exposure to Moderate Altitude in Athletes Exhibiting Exercise-Induced Hypoxemia at Sea-Level

This study examined to what extent athletes exhibiting exercise-induced hypoxemia (EIH) possess an altered redox status at rest, in response to exercise at sea level (SL) and during moderate altitude exposure. EIH was defined as a fall in arterial O₂ saturation of at least 4% during exercise. Nine endurance athletes with EIH and ten without (NEIH) performed a maximal incremental test under three conditions: SL, one (H1) and five (H2) days after arrival to 2400 m. Gas exchange and peripheral capillary oxygen saturation (SpO₂) were continuously monitored. Blood was sampled before exercise and after exercise cessation. Advanced oxidation protein products (AOPP), catalase, ferric-reducing antioxidant power, glutathione peroxidase, superoxide dismutase (SOD) and nitric oxide metabolites (NOx) were measured in plasma by spectrophotometry. EIH athletes had higher AOPP and NOx concentrations at pre- and post-exercise stages compared to NEIH at SL, H2 but not at H1. Only the EIH group experienced increased SOD activity between pre- and post-exercise exercise at SL and H2 but not at H1. EIH athletes had exacerbated oxidative stress compared to the NEIH athletes at SL and H2. These differences were blunted at H1. Oxidative stress did not alter the EIH groups’ aerobic performance and could lead to higher minute ventilation at H2. These results suggest that higher oxidative stress response EIH athletes could be involved in improved aerobic muscle functionality and a greater ventilatory acclimatization during prolonged hypoxia.

Cardiorespiratory Response during the 1-min Sit-to-Stand Test in Chronic Obstructive Pulmonary Disease

PURPOSE

This study aimed to assess the cardiorespiratory response during a 1-min sit-to-stand test (1STS) in comparison with cycling cardiopulmonary exercise test (CPET) in people with chronic obstructive pulmonary disease (COPD) and in healthy subjects and to evaluate whether 1STS may induce leg fatigue in these individuals.

METHODS

Fourteen people with severe COPD and 12 healthy subjects performed a 1STS and a CPET during which cardiorespiratory response, perception of dyspnea, and leg fatigue were assessed. Quadriceps strength was assessed before and after 1STS, and contractile fatigue was defined as a postexercise fall in quadriceps twitch force greater than 15% of resting values.

RESULTS

In COPD, peak V˙O2, V˙E, and HR achieved during 1STS reached 113%, 103%, and 93% of the corresponding values during CPET, respectively. Decrease in SpO2 from preexercise to peak exercise and the magnitude of dynamic hyperinflation were similar between 1STS and CPET. Borg dyspnea and leg fatigue scores were higher for CPET than 1STS. In healthy subjects, peak cardiorespiratory demand and symptom scores were higher during CPET compared with 1STS. A V˙O2 overshoot during recovery was observed only in people with COPD. After 1STS, the V˙O2 half-time recovery of COPD was 152 ± 25 s compared with 74 ± 18 in healthy subjects (P < 0.01). Ten people with COPD and five healthy subjects were considered as fatiguers.

CONCLUSION

The 1STS induced a similar cardiorespiratory stress to that of CPET and was associated with contractile quadriceps fatigue in people with severe COPD. The V˙O2 overshoot and slower recovery time of cardiorespiratory variables seen in COPD demonstrate the clinical relevance of monitoring the recovery phase of exercise.

Long-Term Effectiveness of a Home-Based Pulmonary Rehabilitation in Older People with Chronic Obstructive Pulmonary Disease: A Retrospective Study

Background

Long-term effectiveness of pulmonary rehabilitation (PR) is still uncertain in older people with severe chronic obstructive pulmonary disease (COPD). The objective was to compare the effects of home-based PR in people with COPD above and below the age of 70 years.

Methods

In this retrospective study, 480 people with COPD were recruited and divided into those ≤70 (n=341) and those >70 years of age (n=139). All participants underwent an 8 weeks of home-based PR, consisting of a weekly supervised 90-minute home session. Six-minute stepper test (6MST), timed-up and go test (TUG), Hospital Anxiety and Depression Scale, and Visual Simplified Respiratory Questionnaire (VSRQ) were assessed at baseline (M0), at 2 (M2), 8 (M8), 14 (M14) months after baseline.

Results

The older group was described by fewer current smokers (p <0.001), more long-term oxygen therapy use (p = 0.024), higher prevalence of comorbidities (p<0.001), lower 6MST score and higher TUG score (p<0.001), compared to the younger group. Both groups improved every outcome at M2 compared to baseline. At M2, 88% of people ≤70 years of age and 79% of those above 70 were considered as responders in at least one evaluated parameter (p = 0.013). Both groups maintained the benefits at M14, except for the VSRQ score and the number of responders to this outcome in the older group.

Conclusion

Regardless of the age, personalized home-based PR was effective for people with COPD in the short term. Above 70 years, an ageing effect appeared on the long-term effectiveness of quality of life benefit.

Immediate and 6-week after effects of a rehabilitation program for Ehlers-Danlos syndrome hypermobile type patients: A retrospective study

Ehlers-Danlos syndromes (EDS) are a group of inherited connective tissue disorders with an impaired quality of life in association with fatigue, pain, and kinesiophobia. A retrospective evaluation of the effects of an outpatient rehabilitation program (RP) was performed in Ehlers-Danlos syndrome hypermobile type (hEDS) patients. The 6-minute walk test (6MWT) was used to evaluate functional capacity. Kinesiophobia, fatigue, pain, and quality of life were self-evaluated at the start, at the end, and 6 weeks after the end of the RP. The retrospective analysis of patients' records showed significant improvement for the walked distance during the 6MWT (491.8 ± 72.5 vs. 439.4 ± 100.9 m) maintained at 6-week follow-up (p = .001), significant improvement for kinesiophobia (p = .033) and the impact of fatigue on activity (p = .01), and significant increase for quality of life with in particular improvements of vitality (p = .001). This retrospective study showed encouraging results of a RP for hEDS patients on functional capacity and quality of life, and prospective studies with long-term follow-up are needed to confirm them.

Benefits of a four-week functional restoration program in chronic low back pain patients and three-month follow-up: focus on paraspinal muscle aerobic metabolism responses to exercise

BACKGROUND

Chronic low back pain (CLBP) is a major health concern characterized by paraspinal muscle fatigability. This can be improved following a functional restoration program. Muscle fatigability can be related to impairment in aerobic metabolism responses. In this study, we investigated paraspinal muscles aerobic metabolism in CLBP patients before and after a functional restoration program, in order to determine if the enhancement in patients' condition following the program is associated to changes in metabolism responses.

METHODS

Twenty-two CLBP patients (11 women, 11 men; 41.6±1.8 years; 73.7±3.1 kg; 1.74±0.02 m) were evaluated before and after a 4-week functional restoration program, with exercise therapy as the main component. Three months later, 12 patients were seen for a follow-up visit. During each testing session, patients performed a five-minute isokinetic trunk extension exercise in measuring pulmonary gas exchanges and paraspinal muscle oxygenation. Mechanical efficiency and onset V̇O<inf>2</inf> kinetics were also calculated, in addition to usual questionnaires and exercises designed to evaluate psychosocial and physical factors.

RESULTS

At the end of the program, paraspinal muscle oxygenation, mechanical efficiency, and the V̇O<inf>2</inf> onset kinetics were improved (P<0.05). All measures remained stable during the three-month follow-up except for paraspinal muscle oxygenation, which deteriorated (P<0.05). Return-to-work was associated with the level of workday physical activities and to a decrease in fear-avoidance beliefs.

CONCLUSIONS

At the end of the program, aerobic metabolism responses were improved in paraspinal muscles in patients. These improvements were not associated with return-to-work, which was primarily influenced by socio-psychological factors.

Evolution of blood rheology and its relationship to pulmonary hemodynamic during the first days of exposure to moderate altitude

Blood rheology and hemodynamic parameters have never been explored together during acclimatization to altitude. This study aimed to investigate changes in blood rheology parameters and pulmonary hemodynamics during the first days of real moderate altitude exposure.Seventeen athletes were tested at sea-level, 20 hours after their arrival at 2,400 meters of altitude (H1) and five days later (H2). Blood was sampled to analyze red blood cell (RBC) aggregation, blood viscosity and hematocrit. Pulmonary arterial pressure (PAP), pulmonary capillary pressure (Pcap) and pulmonary vascular resistance (PVR) were assessed by echocardiography.We observed a rise in hematocrit, blood viscosity, RBC aggregation, PAP, Pcap and PVR between sea-level and H1. In H2, RBC aggregation, hematocrit, PAP, Pcap and PVR remained different compared to sea-level and no difference was observed between H1 and H2. Blood viscosity decreased in H2 and returned to sea-level values.Our results suggest that hemoconcentration occurring within the first hours of altitude exposure increased blood viscosity, which contributed to the changes in pulmonary hemodynamic. When blood viscosity decreased in H2, no change occurred in pulmonary hemodynamic parameters suggesting that hypoxic pulmonary vasoconstriction was still present. The elevated RBC aggregation observed after in H2 could participate in the increase of Pcap.

Muscle and cerebral oxygenation during exercise in athletes with exercise-induced hypoxemia: A comparison between sea level and acute moderate hypoxia

The objective of the present study was to evaluate the influence of exercise-induced hypoxemia (EIH) on muscle and cerebral oxygenation responses during maximal exercise in normoxia and in acute moderate hypoxia (fraction of inspired oxygen: 15.3%, 2400 m). EIH was defined as a drop in hemoglobin saturation of at least 4% for at least three consecutive minutes during maximal exercise at sea level. Twenty-five athletes performed incremental treadmill tests to assess maximal oxygen consumption (VO_2max) in normoxia and in hypoxia. Oxygenation of the vastus lateralis muscle and the left prefrontal cortex of the brain was monitored using near-infrared spectroscopy. During the normoxic test, 15 athletes exhibited EIH; they displayed a larger change in muscle levels of oxyhemoglobin (ΔO₂Hb) (p = 0.04) and a greater change in cerebral levels of deoxyhemoglobin (ΔHHb) (p = 0.02) than athletes without EIH (NEIH group). During the hypoxic test, muscle ΔO₂Hb was lower in the EIH group than in the NEIH group (p = 0.03). At VO_2max, hypoxia was associated with a smaller cerebral ΔO₂Hb in both groups, and a greater cerebral ΔHHb compared to normoxia in the NEIH group only (p = 0.02). No intergroup differences in changes in muscle oxygenation were observed. The severity of O₂ arterial desaturation was negatively correlated with changes in total muscle hemoglobin in normoxia (r = -0.48, p = 0.01), and positively correlated with the cerebral ΔHHb in normoxia (r = 0.45, p = 0.02). The occurrence of EIH at sea level was associated with specific muscle and cerebral oxygenation responses to exercise under both normoxia and moderate hypoxia.

Trunk Muscle Aerobic Metabolism Responses in Endurance Athletes, Combat Athletes and Untrained Men

This study investigated aerobic metabolism responses in trunk muscles during a prolonged trunk extension exercise in athletes and untrained young men. The aim was to analyze the adaptations induced by 2 types of sports: one involving intensive use of trunk muscles (i. e., judo), and one known to induce high aerobic capacity in the whole body (i. e., cycling). Eleven judokas, 10 cyclists and 9 healthy untrained young men performed trunk extension exercises on an isokinetic dynamometer. During the first session, muscle strength was assessed during maximal trunk extension. During a second session, a 5-min exercise was performed to investigate aerobic responses with regard to trunk muscles. The near infrared spectroscopy technique and a gas exchange analyzer were used continuously to evaluate mechanical efficiency, V̇O₂ on-set kinetics, trunk muscle deoxygenation and blood volume. Judokas showed greater trunk strength and mechanical efficiency (p<0.05). Cyclists presented faster V̇O₂ on-set kinetics (p<0.05) and greater muscle deoxygenation and blood volume compared to untrained men (p<0.001). These results suggest that practicing judo improves trunk extension efficiency whereas cycling accelerates aerobic pathways and enhances microvascular responses to trunk extension exercise. Sport practice improves aerobic metabolism responses in trunk extensor muscles differently, according to the training specificities.

Cerebral and Muscle Oxygenation during Repeated Shuttle Run Sprints with Hypoventilation

Ten highly-trained Jiu-Jitsu fighters performed 2 repeated-sprint sessions, each including 2 sets of 8 x ~6 s back-and-forth running sprints on a tatami. One session was carried out with normal breathing (RSN) and the other with voluntary hypoventilation at low lung volume (RSH-VHL). Prefrontal and vastus lateralis muscle oxyhemoglobin ([O₂Hb]) and deoxyhemoglobin ([HHb]) were monitored by near-infrared spectroscopy. Arterial oxygen saturation (SpO₂), heart rate (HR), gas exchange and maximal blood lactate concentration ([La]_max) were also assessed. SpO₂ was significantly lower in RSH-VHL than in RSN whereas there was no difference in HR. Muscle oxygenation was not different between conditions during the entire exercise. On the other hand, in RSH-VHL, cerebral oxygenation was significantly lower than in RSN (-6.1±5.4 vs-1.5±6.6 µm). Oxygen uptake was also higher during the recovery periods whereas [La]_max tended to be lower in RSH-VHL. The time of the sprints was not different between conditions. This study shows that repeated shuttle-run sprints with VHL has a limited impact on muscle deoxygenation but induces a greater fall in cerebral oxygenation compared with normal breathing conditions. Despite this phenomenon, performance is not impaired, probably because of a higher oxygen uptake during the recovery periods following sprints.

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 (6MWT_peak and 6MST_peak). 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 (HRr_60%walk, HRr_60%step).

Results

The HRs measured during the 6MST were significantly higher than those measured during the 6MWT. The HRr_60%step was not significantly different from 6MWT₄₅₆ and 6MWT_peak HR (P=0.51; P=0.48). A significant correlation was observed between 6MWT₄₅₆ and 6MWT_peak (r=0.58). The 6MWT₄₅₆ and 6MWT_peak HR were correlated with HRr_60%step (r=0.68 and r=0.62). The VT could be determined in 28 patients. The HR_VT was not different from 6MWT₄₅₆, 6MWT_peak, and HRr_60%step (P=0.57, P=0.41 and P=0.88) and was correlated to 6MWT₄₅₆, 6MWT_peak, and HRr_60%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.

Correlation of gas exchange threshold and first muscle oxyhemoglobin inflection point with time-to-exhaustion during heavy-intensity exercise

BACKGROUND

The twofold aim of the study was to: 1) compare the gas exchange threshold (GET), the first oxyhemoglobin inflection point ([O2Hb]-T), and perceptual threshold as determined during an incremental exercise test, and 2) investigate the link between each threshold and time-to-exhaustion during heavy intensity exercise.

METHODS

Fourteen competitive cyclists performed an incremental exercise test to exhaustion on a cycloergometer to determine the different thresholds and peak workload (Wpeak). The participants then performed a sub-maximal constant workload test (90% Wpeak) to exhaustion to determine time-to-exhaustion. The thresholds were identified from: 1) the first breakpoint in the oxygen uptake vs. carbon dioxide output curve (GET), 2) the [O2Hb]-T, and 3) a rating of 13 in perceived exertion (perceptual threshold: RPE13-T).

RESULTS

Oxygen uptake at the different thresholds was not significantly different (P>0.05). Moreover, GET and [O2Hb]-T were significantly correlated: 1) to each other (r≥0.79; P≤0.001), and 2) to time-to-exhaustion (r=0.81 and r=0.72, respectively; P<0.01). RPE13-T, however, was not significantly correlated with the time-to-exhaustion (P=0.148).

CONCLUSIONS

The anaerobic threshold as identified from GET was concomitant to [O2Hb]-T. Both thresholds were correlated to time-to-exhaustion, and could therefore be used as a performance index in middle-duration events.

Evaluation of muscle oxygenation by near infrared spectroscopy in patients with facioscapulohumeral muscular dystrophy

The purpose of the study was to determine muscle metabolism adaptation to exercise in facioscapulohumeral muscular dystrophy patients (FSHD) and to study the correlation with clinical functional status (6-min walk test). 8 FSHD patients and 15 age-matched healthy controls (Controls) performed two isokinetic constant-load knee extension exercises: (1) at 20% of their maximal extensors' peak torque (i.e., the same relative workload) and (2) at (20N⋅m) (the same absolute workload) for up to 4 min. All exercises consisted of rhythmic, voluntary, isokinetic, concentric contractions of the quadriceps femoris at 90°/s, whereas the flexion was performed passively at the same speed. Muscle oxygenation in the vastus lateralis was evaluated using near-infrared spectroscopy (NIRS). The FSHD patients displayed a lower maximal peak torque than controls (-41%, p < 0.05). During the two-exercise modalities, deoxygenated haemoglobin (HHb) and total haemoglobin volume (tHb) were lower in the FSHD patients (p < 0.05). The initial muscle deoxygenation time delay was shorter in the control group (FSHD: 15.1 ± 4.1 s vs.

CONTROLS

10.4 ± 2.1 s, p < 0.05). Mean response time and maximal peak torque were both correlated with functional impairment (walking endurance). The results suggest that FSHD patients present an impairment in their capacity to deliver or to use oxygen.

Regional cerebral hemodynamic response to incremental exercise is blunted in poorly controlled patients with uncomplicated type 1 diabetes

OBJECTIVE

Cerebral vasoreactivity to pharmacologically induced hypercapnia is impaired in poorly controlled patients with type 1 diabetes but otherwise free from microangiopathy. However, whether this response is also compromised during exercise, a daily-life physiological condition challenging regional cerebral hemodynamics, is unknown. We aimed to investigate prefrontal cortex hemodynamics during incremental maximal exercise in patients with uncomplicated type 1 diabetes, taking into account long-term glycemic control as well as exercise- and diabetes-influenced vasoactive stimuli.

RESEARCH DESIGN AND METHODS

Two groups of patients (type 1 diabetes with adequate glycemic control [T1D-A], n = 8, HbA1c 6.8 ± 0.7% [51 ± 7.7 mmol/mol]; type 1 diabetes with inadequate glycemic control [T1D-I], n = 10, HbA1c 9.0 ± 0.7% [75 ± 7.7 mmol/mol]) were compared with 18 healthy control subjects (CON-A and CON-I) matched for physical activity and body composition. Throughout exercise, near-infrared spectroscopy allowed investigation of changes in oxyhemoglobin (O2Hb), deoxyhemoglobin (HHb), and total hemoglobin (THb) in the prefrontal cortex. Venous and arterialized capillary blood was sampled during exercise to assess for factors that may alter prefrontal cortex hemodynamics and oxygenation.

RESULTS

No differences were observed between T1D-A and CON-A, but VO2max was impaired (P < 0.05) and cerebral blood volume (THb) increase blunted (P < 0.05) in T1D-I compared with CON-I. Nonetheless, O2Hb appeared unaltered in T1D-I probably partly due to blunting of simultaneous neuronal oxygen extraction (i.e., a lower HHb increase; P < 0.05). There were no intergroup differences in arterial oxygen content, Paco2, pH, [K(+)], and free insulin levels.

CONCLUSIONS

Maximal exercise highlights subtle disorders of both hemodynamics and neuronal oxygenation in the prefrontal cortex of poorly controlled patients with type 1 diabetes. These findings may warn clinicians of brain endothelial dysfunction occurring even before overt microangiopathy during exercise.

Effect of additional respiratory muscle endurance training in young well-trained swimmers

While some studies have demonstrated that respiratory muscle endurance training (RMET) improves performances during various exercise modalities, controversy continues about the transfer of RMET effects to swimming performance. The objective of this study was to analyze the added effects of respiratory muscle endurance training (RMET; normocapnic hyperpnea) on the respiratory muscle function and swimming performance of young well-trained swimmers. Two homogenous groups were recruited: ten swimmers performed RMET (RMET group) and ten swimmers performed no RMET (control group). During the 8-week RMET period, all swimmers followed the same training sessions 5-6 times/week. Respiratory muscle strength and endurance, performances on 50- and 200-m trials, effort perception, and dyspnea were assessed before and after the intervention program. The results showed that ventilatory function parameters, chest expansion, respiratory muscle strength and endurance, and performances were improved only in the RMET group. Moreover, perceived exertion and dyspnea were lower in the RMET group in both trials (i.e., 50- and 200-m). Consequently, the swim training associated with RMET was more effective than swim training alone in improving swimming performances. RMET can therefore be considered as a worthwhile ergogenic aid for young competitive swimmers. Key PointsRespiratory muscle endurance training improves the performance.Respiratory muscle endurance training improves the ventilatory function parameters, chest expansion, respiratory muscle strength and endurance.Respiratory muscle endurance training decreases the perceived exertion and dyspnea.Respiratory muscle endurance training can be considered as a worthwhile ergogenic aid for young competitive swimmers.

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.

Cerebral oxygenation during hyperoxia-induced increase in exercise tolerance for untrained men

This study aimed to investigate the involvement of cerebral oxygenation in limitation of maximal exercise. We hypothesized that O2 supplementation improves physical performance in relation to its effect on cerebral oxygenation during exercise. Eight untrained men (age 27 ± 6 years; VO2 max 45 ± 8 ml min(-1) kg(-1)) performed two randomized exhaustive ramp exercises on a cycle ergometer (1 W/3 s) under normoxia and hyperoxia (FIO2 = 0.3). Cerebral (ΔCOx) and muscular (ΔMOx) oxygenation responses to exercise were monitored using near-infrared spectroscopy. Power outputs corresponding to maximal exercise intensity, to threshold of ΔCOx decline (ThCOx) and to the respiratory compensation point (RCP) were determined. Power output (W max = 302 ± 20 vs. 319 ± 28 W) and arterial O2 saturation estimated by pulse oximetry (SpO2 = 95.7 ± 0.9 vs. 97.0 ± 0.5 %) at maximal exercise were increased by hyperoxia (P < 0.05). However, the ΔMOx response during exercise was not significantly modified with hyperoxia. RCP (259 ± 17 vs. 281 ± 25 W) and ThCOx (259 ± 23 vs. 288 ± 30 W) were, however, improved (P < 0.05) with hyperoxia and the ThCOx shift was related to the W max improvement with hyperoxia (r = 0.71, P < 0.05). The relationship between the change in cerebral oxygenation response to exercise and the performance improvement with hyperoxia supports that cerebral oxygenation is limiting the exercise performance in healthy young subjects.

Hyperoxia does not accelerate quadriceps muscle deoxygenation kinetics at the onset of heavy exercise cycle

AIM

The aim of this study was to determine whether an increase in O2 availability induces an alteration of the balance between O2 consumption ((V)O2) and O2 delivery ((Q)O2) at the muscle level. For that, we examined the effect of moderate hyperoxia on muscle deoxygenation kinetics at the onset of heavy-intensity cycling exercise.

METHODS

Eight young male adults performed step transitions from 35 W to heavy-intensity exercise corresponding to a power output half-way between the first ventilatory threshold and (V)O2max in normoxia and in hyperoxia (FIO2=0.30). Muscle deoxygenation (HHb) and total hemoglobin (Hbtot) were monitored continuously by near-infrared spectroscopy. HHb data were fit with a mono-exponential model from the onset of exercise up to 90 seconds.

RESULTS

Hyperoxia neither altered the delay before the increase in HHb (normoxia: 10.7±1.8 s vs. hyperoxia: 9.5±1.9 s; NS) nor the HHb mean response time (normoxia: 20.6±2.8 s vs. hyperoxia: 19.6±2.3 s; NS). Likewise, Hbtot was not different between normoxia and hyperoxia.

CONCLUSION

These results indicate that moderate hyperoxia has no effect on muscle deoxygenation kinetics at the onset of heavy exercise. It suggests that muscle (V)O2 increases at the same rate than O2 delivery when O2 availability is enhanced.

Faster pulmonary oxygen uptake kinetics in children vs adults due to enhancements in oxygen delivery and extraction

This study aimed to examine if the faster pulmonary oxygen uptake (VO2p) phase 2 in children could be explained by increased O2 availability or extraction at the muscle level. For that purpose, O2 availability and extraction were assessed using deoxyhemoglobin (HHb) estimated by near-infrared spectroscopy during moderate-intensity constant load cycling exercise in children and young adults. Eleven prepubertal boys and 12 men volunteered to participate in the study. They performed one maximal graded exercise to determine the power associated with the gas exchange threshold (GET) and four constant load exercises at 90% of GET. VO2p and HHb were continuously monitored. VO2p , HHb, and estimated capillary blood flow (Qcap) kinetics were modelled after a time delay and characterized by the time to achieve 63% of the amplitude (τ) and by mean response time (MRT: time delay + τ), respectively. Mean values of τ for VO2p (P < 0.001), of MRT for HHb (P < 0.01) and of MRT for Qcap (P < 0.001) were significantly shorter in children. Faster VO2p kinetics have been shown in children; these appear due to both faster O2 extraction and delivery kinetics as indicated by faster HHb and Qcap kinetics, respectively.

Time to exhaustion and time spent at a high percentage of VO2max in severe intensity domain in children and adults

The aim of the study was to compare time spent at a high percentage of VO2max (>90% of VO2max) (ts90%), time to achieve 90% of VO2max (ta90%), and time to exhaustion (TTE) for exercise in the severe intensity domain in children and adults. Fifteen prepubertal boys (10.3 ± 0.9 years) and 15 men (23.5 ± 3.6 years) performed a maximal graded exercise to determine VO2max, maximal aerobic power (MAP) and power at ventilatory threshold (PVTh). Then, they performed 4 constant load exercises in a random order at PVTh plus 50 and 75% of the difference between MAP and PVTh (PΔ50 and PΔ75) and 100 and 110% of MAP (P100 and P110). VO2max was continuously monitored. The P110 test was used to determine maximal accumulated oxygen deficit (MAOD). No significant difference was found in ta90% between children and adults. ts90% and TTE were not significantly different between children and adults for the exercises at PΔ50 and PΔ75. However, ts90% and TTE during P100 (p < 0.05 and p < 0.01, respectively) and P110 (p < 0.001) exercises were significantly shorter in children. Children had a significantly lower MAOD than adults (34.3 ± 9.4 ml · kg vs. 53.6 ± 11.1 ml · kg). A positive relationship (p < 0.05) was obtained between MAOD and TTE values during the P100 test in children. This study showed that only for intensities at, or higher than MAP, lower ts90% in children was linked to a reduced TTE, compared to adults. Shorter TTE in children can partly be explained by a lower anaerobic capacity (MAOD). These results give precious information about exercise intensity ranges that could be used in children's training sessions. Moreover, they highlight the implication of both aerobic and anaerobic processes in endurance performances in both populations.

Continuous vs. interval aerobic training in 8- to 11-year-old children

The aim of the present study was to show if the use of continuous-running training vs. intermittent-running training has comparable or distinct impact on aerobic fitness in children. At first, children were matched according to their chronological age, their biological age (secondary sexual stages), and their physical activity or training status. Then, after randomization 3 groups were composed. Sixty-three children (X 9.6 +/- 1.0 years) were divided into an intermittent-running training group (ITG, 11 girls and 11 boys), a continuous-running training group (CTG, 10 girls and 12 boys), and a control group (CG, 10 girls and 9 boys). Over 7 weeks, ITG and CTG participated in 3 running sessions per week. Before and after the training period, they underwent a maximal graded test to determine peak oxygen uptake (peak VO2) and maximal aerobic velocity (MAV). Intermittent training consisted of short intermittent runs with repeated exercise and recovery sequences lasting from 5/15 to 30/30 seconds. With respect to continuous training sessions, repeated exercise sequences lasted from 6' to 20'. Training-effect threshold for statistical significance was set at p < 0.05. After training, peak VO2 was significantly improved in CTG (+7%, p < 0.001) and ITG (+4.8%, p < 0.001), whereas no difference occurred for the CG (-1.5%). Similarly, MAV increased significantly (p < 0.001) in both CTG (+8.7%) and ITG (+6.4%) with no significant change for CG. Our results demonstrated that both continuous and intermittent-running sessions induced significant increase in peak VO2 and MAV. Therefore, when adequate combinations of intensity/duration exercises are offered to prepubertal children, many modalities of exercises can successfully be used to increase their aerobic fitness. Aerobic running training is often made up of regular and long-distance running exercises at moderate velocity, which causes sometimes boredom in young children. During the developmental years, it seems therefore worthwhile to use various training modalities, to make this activity more attractive and thus create conditions for progress and enhanced motivation.

Heterogeneity of muscle deoxygenation kinetics during two bouts of repeated heavy exercises

This study examines the effect of prior heavy exercise on the spatial distribution of muscle deoxygenation kinetics at the onset of heavy-intensity cycling exercise. Young untrained male adults (n = 16) performed two consecutive bouts of 6 min of high intensity cycle exercise separated by 6 min at 35 W. Muscle deoxygenation (HHb) was monitored continuously by near-infrared spectroscopy at eight sites in the quadriceps. Prior heavy exercise reduced the delay before the increase in HHb (9 +/- 2 vs. 5 +/- 2 s; P < 0.001). The standard deviation of TD HHb of the eight sites was decreased by the performance of prior exercise (1.1 +/- 0.5 vs. 0.8 +/- 0.4 s; P < 0.05). The transient decrease in HHb during the first 10 s of exercise was less during the second bout than during the first bout (0.6 +/- 0.6 vs. 0.3 +/- 0.3 A.U.; P < 0.01). The standard deviation of this decrease was also reduced by prior exercise (0.5 +/- 0.3 vs. 0.3 +/- 0.2 A.U.; P < 0.01). Lastly, prior exercise decreased significantly the standard deviation of the HHb rise during the time period corresponding to the pulmonary VO(2) slow component. These results indicate that prior heavy exercise reduced the spatial heterogeneity of muscle deoxygenation kinetics at the early onset of heavy exercise and during the development of the pulmonary VO(2) slow component. It indicates that the distribution of the VO(2)/O(2) delivery ratio within muscle was improved by the performance of a prior exercise.

At identical isowork rates, ageing influences cardiorespiratory adaptations in COPD out-patients

PURPOSE

To determine the extent to which younger COPD patients improve their cardiorespiratory function during exercise in comparison with older COPD patients, as a result of exercise training.

METHODS

Thirty-nine COPD patients underwent an exercise program. They were divided into two groups: a younger group (57.2+/-1.0 years, n=18 patients) and an older group (68.8+/-0.6 years, n=21 patients). Forced expiratory volume in 1s was lower than 55% of the predicted value for all patients.

RESULTS

After training, VO2 symptom-limited significantly improved by 10.3% and 8.4% for the younger and older COPD patients, respectively (P<0.05). Peak power significantly improved by 25.2% and 17.8% in the younger and older groups, respectively (P<0.05) with a greater improvement for the younger group (P<0.05). At submaximal exercise, ventilation and heart rate significantly decreased after training in the younger COPD patients (P<0.05) with no significant modification in the older COPD patients.

CONCLUSIONS

The results suggest that all patients with COPD benefit from exercise rehabilitation at maximal exercise workload, however, according to their age, submaximal cardiorespiratory adaptations were greater in younger patients.

Optimal Exercise Intensity in Trained Elderly Men and Women

The purpose of our investigation was to suggest a new approach to determine exercise intensities in master elderly athletes. Sixteen trained elderly men (63.0 +/- 2.9 years) and 8 trained elderly women (62.3 +/- 5.5 years), performed an exhaustive exercise test on a cycle ergometer. Rating of perceived exertion (RPE) and heart rate reserve (HRr) were determined at the first and second ventilatory thresholds (VT1 and VT2). There was no significant difference between genders in RPE and HRr, whatever the exercise intensity. RPE scores corresponded to 12.4 +/- 0.9 in men and 12.7 +/- 1.3 in women at VT1. At VT2, RPE was 15.2 +/- 0.8 and 15.3 +/- 1.1 in men and women, respectively. HR at VT1 corresponded to 59.3 +/- 7.0% in men and 59.5 +/- 5.1% in women, whereas at VT2, HR was measured at 80.5 +/- 6.4% and 79.5 +/- 5.9% HRr, in men and women, respectively. Because it is not practical to measure VT1 and VT2 in routine clinical practice, the present study indicated that, in trained older men and women, the RPE value of 12 - 13 and/or 60 % HRr might be used to detect the exercise intensity at VT1. An RPE score of 15 and/or 80 % HRr would appear to be good indexes in the prescription of exercise intensity at VT2.

Difference in breathing strategies during exercise between trained elderly men and women

This study compared the ventilatory responses and exercise tidal flow-volume (Vt) loops during exercise in order to analyze the influence of gender on breathing strategy in a fit aging population. Sixteen trained elderly men (63.0+/-2.9 years) and eight peer women (62.3 +/- 5.5 years) performed an incremental test on a cycle ergometer. At 90% maximal oxygen consumption (VO2max), the women presented a significantly higher expiratory flow limitation (EFL) than the men (38 +/- 10 vs 17 +/- 8% of Vt, respectively) (P<0.01) and a lower value of expiratory reserve volume relative to forced vital capacity (FVC) compared with the men (16.8 +/- 5.3% vs 23.0 +/- 5.2%, respectively) (P<0.05). Inspiratory reserve volume relative to FVC was significantly higher in women than men at 50% (P<0.05), 70% (P<0.01) and 90%VO2max (25.2 +/- 5.4% vs 12.2 +/- 4.2%, respectively, at 90%VO2max) (P<0.01). Mechanical ventilatory constraints occurred in trained elderly men and women. However, different breathing strategies were observed relative to gender. A significantly higher EFL was measured in women, whereas men rather presented a dynamic hyperinflation. This specific breathing strategy measured in trained elderly women would induce lower ventilatory efficiency than in peer men.

Respiratory Muscle Oxygenation Kinetics: Relationships with Breathing Pattern during Exercise

This work aimed to investigate accessory respiratory muscle oxygenation (RMO(2)) during exercise, using near-infrared spectroscopy, and to study relationships between RMO(2) kinetics and breathing parameters. Nineteen young males (19.3 +/- 1.5 years) performed a maximal incremental test on a cycle ergometer. Changes in breathing pattern were characterized by accelerated rise in the breathing frequency (f (Racc)), plateau of tidal volume (V (Tplateau)) and inflection point in the V. (E)/V (T) relationship (V. (E)/V (T inflection)). First and second ventilatory thresholds (VT1 and VT2) were also determined. RMO (2) kinetics were monitored by NIRS on the serratus anterior. During exercise, all subjects showed reduced RMO (2) (deoxygenation) with a breakdown (B-RMO(2)) at submaximal workload (86 % .VO(2max)). .VO(2) corresponding to B-RMO (2) and to f (Racc), V (Tplateau), .V(E)/V(T inflection), or VT2 were not different. Relationships were found between the .VO(2) at B-RMO(2) and the .VO(2) at f (Racc) (r = 0.88, p < 0.001), V (Tplateau) (r = 0.84, p < 0.001), V. (E)/V (T inflection) (r = 0.58, p < 0.05) or VT2 (r = 0.79, p < 0.001). The amplitude of RMO(2) at maximal workload was weakly related to .VO(2max) (r = 0.58, p < 0.05). B-RMO (2) seems to be due to the change in breathing pattern and especially to the important rise in breathing frequency at the VT2 exercise level. Moreover, subjects who exhibit higher .VO(2max) also exhibit a higher decrease in respiratory muscle oxygenation during exercise.