Ventilatory patterns differ between maximal running and cycling

Physiological Profiles of Recreational Runners and Cyclists Aged 20 to 60 Years

Human physical activities may bring potential health benefits. The aim of our study was to compare body composition, lung function and aerobic fitness as a function of age in a cross-sectional study of 277 recreational cyclists (men: n = 163, women: n = 114) and 377 recreational runners (men: n = 239, women: n = 138) aged 20 to 60 years, with a training volume of about 2000 to 4000 km per year for cyclists and 25 to 60 km per week for runners. The survey focused on comparing the values of body composition, lung function and aerobic fitness in dependence on age. The results suggest that recreational cycling and running is associated with a favorable body composition and increased physical fitness, where the percentage of body fat in athletes corresponds to about 70–90% of the population norm, while physical fitness indices, maximum oxygen consumption and maximum exercise performance corresponded at about 140 to 150% of the population norms. The study confirms the assumption that the decrease in physiological functions and/or physical condition with age is much slower in those who participate in recreational sports than in the general nonsports population.

Intercostal Muscles Oxygenation and Breathing Pattern during Exercise in Competitive Marathon Runners

The study aimed to evaluate the association between the changes in ventilatory variables (tidal volume (Vt), respiratory rate (RR) and lung ventilation (V.E)) and deoxygenation of m.intescostales (∆SmO₂-m.intercostales) during a maximal incremental exercise in 19 male high-level competitive marathon runners. The ventilatory variables and oxygen consumption (V.O₂) were recorded breath-by-breath by exhaled gas analysis. A near-infrared spectroscopy device (MOXY^®) located in the right-hemithorax allowed the recording of SmO₂-m.intercostales. To explore changes in oxygen levels in muscles with high demand during exercise, a second MOXY^® records SmO₂-m.vastus laterallis. The triphasic model of exercise intensity was used for evaluating changes in SmO₂ in both muscle groups. We found that ∆SmO₂-m.intercostales correlated with V.O_2-peak (r = 0.65; p = 0.002) and the increase of V.E (r = 0.78; p = 0.001), RR (r = 0.54; p = 0.001), but not Vt (p = 0.210). The interaction of factors (muscles × exercise-phases) in SmO₂ expressed as an arbitrary unit (a.u) was significant (p = 0.005). At VT1 there was no difference (p = 0.177), but SmO₂-m.intercostales was higher at VT2 (p < 0.001) and V.O_2-peak (p < 0.001). In high-level competitive marathon runners, the m.intercostales deoxygenation during incremental exercise is directly associated with the aerobic capacity and increased lung ventilation and respiratory rate, but not tidal volume. Moreover, it shows less deoxygenation than m.vastus laterallis at intensities above the aerobic ventilatory threshold.

V[Combining Dot Above]O2peak Comparison of a Treadmill Vs. Cycling Protocol in Elite Teenage Competitive Runners, Cyclists, and Swimmers

ABSTRACT

Marko, D, Bahenský, P, Snarr, RL, and Malátová, R. V[Combining Dot Above]O2peak Comparison of a treadmill vs. cycling protocol in elite teenage competitive runners, cyclists, and swimmers. J Strength Cond Res XX(X): 000-000, 2021-The purpose of this study was to compare the cardiorespiratory and metabolic responses of a maximal graded exercise test (GXT) on a treadmill and cycle ergometer in elite-level, youth competitive athletes. Thirty-one athletes (11 distance runners, 11 mountain-bike cyclists, and 9 long-distance swimmers) were randomly selected to complete either a running or cycling GXT on the first day, followed by the alternative 72 hours apart. The initial work rate for each GXT was set at 50% of the individuals' previously established V[Combining Dot Above]O2peak to elicit fatigue within 8-12 minutes. For the treadmill protocol, speed was increased by 1 km·h-1 each minute, with a constant 5% grade, until volitional fatigue. Cycle ergometer work rate was increased by 30 W every minute until volitional fatigue or the inability to maintain proper cadence (i.e., 100 ± 5 rev·min-1). Throughout both testing sessions, V[Combining Dot Above]O2peak, heart rate [HR] peak, breathing frequency (BF), tidal volume (VT), and minute ventilation (VE) were assessed and used to compare within-sport differences. Runners displayed a higher V[Combining Dot Above]O2peak (∼7%; d = 0.92), HRpeak (4%; d = 0.77), VE (6%; d = 0.66), and BF (12%; d = 0.62) on the treadmill vs. cycle. However, the cycling group demonstrated a greater V[Combining Dot Above]O2peak (∼8%; d = 0.92), VT (∼14%; d = 0.99), and VE (∼9%; d = 0.78) on the cycle, despite no change in HRpeak. For swimmers, the treadmill GXT elicited higher values in V[Combining Dot Above]O2peak (∼5%; d = 0.75), BF (∼11.5%; d = 0.78), and HRpeak (3%; d = 0.69). Collectively, these findings indicate that exercise mode may greatly affect physiological outcome variables and should be considered before exercise prescription and athletic monitoring.

Cardiorespiratory Responses to Constant and Varied-Load Interval Training Sessions

PURPOSE

To compare the cardiorespiratory responses of a traditional session of high-intensity interval training session with that of a session of similar duration and average load, but with decreasing workload within each bout in cyclists and runners.

METHODS

A total of 15 cyclists (maximal oxygen uptake [V˙O2max] 62 [6] mL·kg-1·min-1) and 15 runners (V˙O2max 58 [4] mL·kg-1·min-1) performed both sessions at the maximal common tolerable load on different days. The sessions consisted of four 4-minute intervals interspersed with 3 minutes of active recovery. Power output was held constant for each bout within the traditional day, whereas power started 40 W (2 km·h-1) higher and finished 40 W (2 km·h-1) lower than average within each bout of the decremental session.

RESULTS

Average oxygen uptake during the high-intensity intervals was higher in the decremental session in cycling (89 [4]% vs 86 [5]% of V˙O2max, P = .002) but not in running (91 [4]% vs 90 [4]% of V˙O2max, P = .38), as was the time spent >90% of V˙O2max and the time spent >90% of peak heart rate. Average heart rate (P < .001), pulmonary ventilation (P < .001), and blood lactate concentration (P < .001) were higher during the decremental sessions in both cycling and running.

CONCLUSIONS

Higher levels of physiological perturbations were achieved during decremental sessions in both cycling and running. These differences were, however, more prominent in cycling, thus making cycling a more attractive modality for testing the effects of a training intervention.

Inhaled albuterol increases estimated ventilatory capacity in nonasthmatic children without and with obesity

Forced mid-expiratory flow (i.e., isoFEF_25-75) may increase with a short-acting β₂-agonist in nonasthmatic children without bronchodilator responsiveness. This could also increase estimated ventilatory capacity along mid-expiration (V̇Ecap_25-75), especially in vulnerable children with obesity who exhibit altered breathing mechanics. We estimated V̇Ecap_25-75 pre- and post-albuterol treatment in 8-12yo children without (n = 28) and with (n = 46) obesity. A two-way ANOVA was performed to determine effects of an inhaled bronchodilator (pre-post) and obesity (group) on isoFEF_25-75 and V̇Ecap_25-75. There was no group by bronchodilator interaction or main group effect on outcome variables. However, a significant main effect of the bronchodilator was detected in spirometry parameters, including a substantial increase in isoFEF_25-75 (17.1 ± 18.0 %) and only a slight (non-clinical) but significant increase in FEV₁ (2.4 ± 4.3 %). V̇Ecap_25-75 significantly increased with albuterol (+11.7 ± 10.6 L/min; +15.8 ± 13.9 %). These findings imply potentially important increases in ventilatory reserve with a bronchodilator in nonasthmatic children without and with obesity, which could potentially influence respiratory function at rest and during exercise.

Exercise-induced elevations in cerebral blood velocity are greater in running compared to cycling at higher intensities

The optimal exercise intensity and modality for maximizing cerebral blood flow (CBF) and hence potential exposure to positive, hemodynamically derived cerebral adaptations is yet to be fully determined. This study compared CBF velocity responses between running and cycling across a range of exercise intensities. Twenty-six participants (12 females; age: 26 ± 8 years) completed four exercise sessions; two mode-specific maximal oxygen consumption (VO2max ) tests, followed by (order randomized) two incremental exercise protocols (3-min stages at 35%, 50%, 65%, 80%, 95% VO2max ). Continuous measures of middle cerebral artery velocity (MCAv), oxygen consumption, end-tidal CO2 (PET CO2 ), and heart rate were obtained. Modality-specific MCAv changes were observed for the whole group (interaction effect: p = .01). Exercise-induced increases in MCAvmean during cycling followed an inverted-U pattern, peaking at 65% VO2max (Δ12 ± 7 cm/s from rest), whereas MCAvmean during running increased linearly up to 95% VO2max (change from rest: Δ12 ± 13 vs. Δ7 ± 8 cm/s for running vs. cycling at 95% VO2max ; p = .01). In contrast, both modalities had an inverted-U pattern for PET CO2 changes, although peaked at different intensities (running: 50% VO2max , Δ6 ± 2 mmHg; cycling: 65% VO2max , Δ7 ± 2 mmHg; interaction effect: p = .01). Further subgroup analysis revealed that the running-specific linear MCAvmean response was fitness dependent (Fitness*modality*intensity interaction effect: p = .04). Above 65% VO2max , fitter participants (n = 16; male > 45 mL/min/kg and female > 40 mL/min/kg) increased MCAvmean up to 95% VO2max , whereas in unfit participants (n = 7, male < mL/min/kg and female < 35 mL/min/kg) MCAvmean returned toward resting values. Findings demonstrate that modality- and fitness-specific profiles for MCAvmean are seen at exercise intensities exceeding 65% VO2max .

Thoracic gas compression during forced expiration is greater in men than women

Intrapleural pressure during a forced vital capacity (VC) maneuver is often in excess of that required to generate maximal expiratory airflow. This excess pressure compresses alveolar gas (i.e., thoracic gas compression [TGC]), resulting in underestimated forced expiratory flows (FEFs) at a given lung volume. It is unknown if TGC is influenced by sex; however, because men have larger lungs and stronger respiratory muscles, we hypothesized that men would have greater TGC. We examined TGC across the "effort-dependent" region of VC in healthy young men (n = 11) and women (n = 12). Subjects performed VC maneuvers at varying efforts while airflow, volume, and esophageal pressure (POES ) were measured. Quasistatic expiratory deflation curves were used to obtain lung recoil (PLUNG ) and alveolar pressures (i.e., PALV  = POES -PLUNG ). The raw maximal expiratory flow-volume (MEFVraw ) curve was obtained from the "maximum effort" VC maneuver. The TGC-corrected curve was obtained by constructing a "maximal perimeter" curve from all VC efforts (MEFVcorr ). TGC was examined via differences between curves in FEFs (∆FEF), area under the expiratory curves (∆AEX ), and estimated compressed gas volume (∆VGC) across the VC range. Men displayed greater total ∆AEX (5.4 ± 2.0 vs. 2.0 ± 1.5 L2 ·s-1 ; p < .001). ∆FEF was greater in men at 25% of exhaled volume only (p < .05), whereas ∆VGC was systematically greater in men across the entire VC (main effect; p < .05). PALV was also greater in men throughout forced expiration (p < .01). Taken together, these findings demonstrate that men display more TGC, occurring early in forced expiration, likely due to greater expiratory pressures throughout the forced VC maneuver.

Veterans with Gulf War Illness exhibit distinct respiratory patterns during maximal cardiopulmonary exercise

INTRODUCTION

The components of minute ventilation, respiratory frequency and tidal volume, appear differentially regulated and thereby afford unique insight into the ventilatory response to exercise. However, respiratory frequency and tidal volume are infrequently reported, and have not previously been considered among military veterans with Gulf War Illness. Our purpose was to evaluate respiratory frequency and tidal volume in response to a maximal cardiopulmonary exercise test in individuals with and without Gulf War Illness.

MATERIALS AND METHODS

20 cases with Gulf War Illness and 14 controls participated in this study and performed maximal cardiopulmonary exercise test on a cycle ergometer. Ventilatory variables (minute ventilation, respiratory frequency and tidal volume) were obtained and normalized to peak exercise capacity. Using mixed-design analysis of variance models, with group and time as factors, we analyzed exercise ventilatory patterns for the entire sample and for 11 subjects from each group matched for race, age, sex, and height.

RESULTS

Despite similar minute ventilation (p = 0.57, η2p = 0.01), tidal volume was greater (p = 0.02, η2p = 0.16) and respiratory frequency was lower (p = 0.004, η2p = 0.24) in Veterans with Gulf War Illness than controls. The findings for respiratory frequency remained significant in the matched subgroup (p = 0.004, η2p = 0.35).

CONCLUSION

In our sample, veterans with Gulf War Illness adopt a unique exercise ventilatory pattern characterized by reduced respiratory frequency, despite similar ventilation relative to controls. Although the mechanism(s) by which this pattern is achieved remains unresolved, our findings suggest that the components of ventilation should be considered when evaluating clinical conditions with unexplained exertional symptoms.

Expiratory flow limitation under moderate hypobaric hypoxia does not influence ventilatory responses during incremental running in endurance runners

We tested whether expiratory flow limitation (EFL) occurs in endurance athletes in a moderately hypobaric hypoxic environment equivalent to 2500 m above sea level and, if so, whether EFL inhibits peak ventilation ( V ˙ Epeak ), thereby exacerbating the hypoxia-induced reduction in peak oxygen uptake ( V ˙ O2peak ). Seventeen young male endurance runners performed incremental exhaustive running on separate days under hypobaric hypoxic (560 mmHg) and normobaric normoxic (760 mmHg) conditions. Oxygen uptake ( V ˙ O2 ), minute ventilation ( V ˙ E), arterial O2 saturation (SpO2 ), and operating lung volume were measured throughout the incremental exercise. Among the runners tested, 35% exhibited EFL (EFL group, n = 6) in the hypobaric hypoxic condition, whereas the rest did not (Non-EFL group, n = 11). There were no differences between the EFL and Non-EFL groups for V ˙ Epeak and V ˙ O2peak under either condition. Percent changes in V ˙ Epeak (4 ± 4 vs. 2 ± 4%) and V ˙ O2peak (-18 ± 6 vs. -16 ± 6%) from normobaric normoxia to hypobaric hypoxia also did not differ between the EFL and Non-EFL groups (all P > 0.05). No differences in maximal running velocity, SpO2 , or operating lung volume were detected between the two groups under either condition. These results suggest that under the moderate hypobaric hypoxia (2500 m above sea level) frequently used for high-attitude training, ~35% of endurance athletes may exhibit EFL, but their ventilatory and metabolic responses during maximal exercise are similar to those who do not exhibit EFL.

Preparation for Endurance Competitions at Altitude: Physiological, Psychological, Dietary and Coaching Aspects. A Narrative Review

It was the Summer Olympic Games 1968 held in Mexico City (2,300 m) that required scientists and coaches to cope with the expected decline of performance in endurance athletes and to establish optimal preparation programs for competing at altitude. From that period until now many different recommendations for altitude acclimatization in advance of an altitude competition were proposed, ranging from several hours to several weeks. Those recommendations are mostly based on the separate consideration of the physiology of acclimatization, psychological issues, performance changes, logistical or individual aspects, but there is no review considering all these aspects in their entirety. Therefore, the present work primarily focusses on the period of altitude sojourn prior to the competition at altitude based on physiological and psychological aspects complemented by nutritional and sports practical considerations.

Influence of high-intensity interval training on ventilatory efficiency in trained athletes

The aim of this study was to investigate the effects of 3 weeks high-intensity interval training (HIIT) on ventilatory efficiency (V_E/VCO₂ slope) in endurance athletes. Sixteen male well-trained (67.72 ml kg min^-1) athletes participated in this study. Each participant performed an incremental exercise test with gas analysis (i.e. V_E, VO₂) and a 400 m running field test (T400m) before and after the 3 weeks intervention period. HIIT group (HIITG) performed 11 HIIT sessions consisting of four 4-min interval bouts at an exercise intensity of 90-95% of the VO_2max, separated by 4-min active recovery periods (work/rest ratio = 1:1). No significant differences were found in the parameters studied. Ventilatory efficiency (up to VT₂ and up to exhaustion) did not show any change in HIITG after training intervention (ES = 0.24 HIITG; ES = 0.21 CG). No significant changes were observed on ventilation (V_Emax; ES = 0.38). VO_2max and T400 m did not show a significant improvement after the training period (no interaction time × group, p < .05) (ES = 0.43 and ES = 0.75 respectively). These results do not support the hypothesis that 3 weeks of HIIT could modify the ventilatory efficiency response in well-trained athletes. Furthermore, they show the lack of relationship between ventilatory efficiency and sport performance.

Premature birth affects the degree of airway dysanapsis and mechanical ventilatory constraints

NEW FINDINGS

What is the central question of this study? Adult survivors of preterm birth without (PRE) and with bronchopulmonary dysplasia (BPD) have airflow obstruction at rest and significant mechanical ventilatory constraints during exercise compared with those born at full term (CON). Do PRE/BPD have smaller airways, indexed via the dysanapsis ratio, than CON? What is the main finding and its importance? The dysanapsis ratio was significantly smaller in BPD and PRE compared with CON, with BPD having the smallest dysanapsis ratio. These data suggest that airflow obstruction in PRE and BPD might be because of smaller airways than CON. Adult survivors of very preterm birth (≤32 weeks gestational age) without (PRE) and with bronchopulmonary dysplasia (BPD) have obstructive lung disease as evidenced by reduced expiratory airflow at rest and have significant mechanical ventilatory constraints during exercise. Airflow obstruction, in any conditions, could be attributable to several factors, including small airways. PRE and/or BPD could have smaller airways than their counterparts born at full term (CON) owing to a greater degree of dysanaptic airway development during the pre- and/or postnatal period. Thus, the purpose of the present study was to compare the dysanapsis ratio (DR), as an index of airway size, between PRE, BPD and CON. To do so, we calculated DR in PRE (n = 21), BPD (n = 14) and CON (n = 34) individuals and examined flow-volume loops at rest and during submaximal exercise. The DR, using multiple estimates of static recoil pressure, was significantly smaller in PRE and BPD (0.16 ± 0.05 and 0.10 ± 0.03 a.u.) compared with CON (0.22 ± 0.04 a.u.; both P < 0.001) and smallest in BPD (P < 0.001). The DR was significantly correlated with peak expiratory airflow at rest (r = 0.42; P < 0.001) and the extent of expiratory flow limitation during exercise (r = 0.60; P < 0.001). Our findings suggest that PRE/BPD might have anatomically smaller airways than CON, which might help to explain their lower expiratory airflow rate at rest and during exercise and further our understanding of the consequences of preterm birth and neonatal O₂ therapy.

Respiratory muscle strength is decreased after maximal incremental exercise in trained runners and cyclists

The respiratory muscle fatigue seems to be able to limit exercise performance and may influence the determination of maximal oxygen uptake (V̇O_2max) or maximum aerobic work rate during maximal incremental test. The aim of this study was therefore to investigate whether maximal incremental exercise decreases respiratory muscle strength. We hypothesized that respiratory muscle strength (maximal pressure) will decrease after maximal incremental exercise to exhaustion. 36 runners and 23 cyclists completed a maximal incremental test on a treadmill or a cycle ergometer with continuous monitoring of expired gases. Maximal inspiratory (MIP) and expiratory (MEP) pressure measurements were taken at rest and post- exercise. At rest, the MIP and MEP were 140±25 and 172±27 in runners vs. 115±26 and 146±33 in cyclists (p<0.05 between groups, respectively). The rest values of MIP and MEP were correlated to the V̇O_2peak in all athletes, r=0.34, p<0.01 and r=0.36, p<0.01, respectively. At exhaustion, the MIP and MEP decreased significantly post- test by 13±7% and 13±5% in runners vs. 17±11% and 15±10% in cyclists (p>0.05), respectively. Our results suggest that respiratory muscle strength is decreased following maximal incremental exercise in trained runners and cyclists.

Neck inspiratory muscle activation patterns during well-controlled inspiration

PURPOSE

Surprisingly, the activation characteristics of the neck inspiratory muscles as a function of key inspiratory mechanical parameters have yet to be demonstrated experimentally under well-controlled conditions. This study aimed to elucidate the muscle activation patterns of the neck inspiratory muscles by strictly controlling flow rate and lung volume.

METHODS

Thirteen healthy subjects matched their inspiratory flow rate at approximately 20-100% of peak flow rate (PFR) as steady as possible during inspiration. Amplitude of surface electromyogram (EMG) of the sternocleidomastoid (SCM) and scalene were calculated for every increase in %PFR over a duration corresponding to an increase in lung volume by 10% of forced vital capacity (FVC), as well as for every 5% increment of FVC over a point corresponding to an increase in flow rate by 20%PFR to determine the %PFR-EMG and %FVC-EMG relations, respectively.

RESULTS

Regression analyses showed that EMGs of the neck inspiratory muscles exponentially increased with increase in %PFR and their associated variables which reflect recruitment onset when increasing flow rate increased with increasing %FVC. In %FVC-EMG relation, a linear regression analysis showed positive slope at all %PFR and positive y-intercept at 80% PFR.

CONCLUSIONS

The main new finding is that the neck inspiratory muscle activities increase with flow rate as well as lung volume. The positive y-intercept of the %FVC-EMG relation at higher %PFR indicates that the neck inspiratory muscles are always activated even when lung volume level is low, implying that SCM is not necessarily an "accessory" muscle as described in previous observations.

Prevalence of Exercise-Induced Arterial Hypoxemia in Distance Runners at Sea Level

PURPOSE

It has been reported that ~50% of endurance-trained men demonstrate exercise-induced arterial hypoxemia (EIAH) during heavy exercise. However, this often-cited prevalence rate comes from a single study using a cohort of 25 highly trained men who completed maximal cycle ergometry. As arterial oxyhemoglobin saturation (SpO2) during maximal exercise is reported to be significantly lower during treadmill versus cycle ergometry in the same subjects, we hypothesized that the prevalence of EIAH would be greater than previously reported (and commonly referenced) in a larger cohort of highly endurance-trained men during maximal treadmill running.

METHODS

Data from 124 highly trained male distance runners (V˙O2max range = 60.3-84.7 mL·kg·min) were retrospectively examined from previously published studies completed in the Indiana University Human Performance Laboratory. Subjects completed a constant speed, progressive-grade treadmill exercise test to volitional exhaustion, and arterial oxyhemoglobin saturation (SaO2ear) in all subjects was estimated using the same oximeter (Hewlett Packard 47201A).

RESULTS

Using similar inclusion criteria as previously published for highly trained (V˙O2max > 68 mL·kg·min) and for EIAH (SaO2ear ≤ 91%), 55 of 79 subjects (70%) exhibited exercise-induced arterial desaturation. Across all 124 subjects, 104 (84%) demonstrated at least moderate EIAH (SaO2ear ≤ 93%) during maximal treadmill exercise. SaO2ear was significantly yet weakly correlated with V˙E/V˙O2 (P < 0.01, r = 0.28) and V˙E/V˙CO2 (P < 0.001, r = 0.33) but not with V˙O2max.

CONCLUSION

These results indicate that the prevalence of EIAH in highly trained men during maximal treadmill exercise at sea level is greater compared with previously suggested data, with exercise mode perhaps playing a factor in the number of athletes who experience EIAH.

Graded Exercise Testing Protocols for the Determination of VO2max: Historical Perspectives, Progress, and Future Considerations

Graded exercise testing (GXT) is the most widely used assessment to examine the dynamic relationship between exercise and integrated physiological systems. The information from GXT can be applied across the spectrum of sport performance, occupational safety screening, research, and clinical diagnostics. The suitability of GXT to determine a valid maximal oxygen consumption (VO₂max) has been under investigation for decades. Although a set of recommended criteria exists to verify attainment of VO₂max, the methods that originally established these criteria have been scrutinized. Many studies do not apply identical criteria or fail to consider individual variability in physiological responses. As an alternative to using traditional criteria, recent research efforts have been directed toward using a supramaximal verification protocol performed after a GXT to confirm attainment of VO₂max. Furthermore, the emergence of self-paced protocols has provided a simple, yet reliable approach to designing and administering GXT. In order to develop a standardized GXT protocol, additional research should further examine the utility of self-paced protocols used in conjunction with verification protocols to elicit and confirm attainment of VO₂max.

Ventilatory acclimatisation is beneficial for high-intensity exercise at altitude in elite cyclists

AIM

The aim of this study was to examine the relationship between ventilatory adaptation and performance during altitude training at 2700 m.

METHODS

Seven elite cyclists (age: 21.2 ± 1.1 yr, body mass: 69.9 ± 5.6 kg, height 176.3 ± 4.9 cm) participated in this study. A hypoxic ventilatory response (HVR) test and a submaximal exercise test were performed at sea level prior to the training camp and again after 15 d at altitude (ALT15). Ventilation (VE), end-tidal carbon-dioxide partial pressure (PETCO2) and oxyhaemoglobin saturation via pulse oximetry (SpO2) were measured at rest and during submaximal cycling at 250 W. A hill climb (HC) performance test was conducted at sea level and after 14 d at altitude (ALT14) using a road of similar length (5.5-6 km) and gradient (4.8-5.3%). Power output was measured using SRM cranks. Average HC power at ALT14 was normalised to sea level power (HC%). Multiple regression was used to identify significant predictors of performance at altitude.

RESULTS

At ALT15, there was a significant increase in resting VE (10.3 ± 1.9 vs. 12.2 ± 2.4 L·min(-1)) and HVR (0.34 ± 0.24 vs. 0.71 ± 0.49 L·min(-1)·%(-1)), while PETCO2 (38.4 ± 2.3 vs. 32.1 ± 3.3 mmHg) and SpO2 (97.9 ± 0.7 vs. 94.0 ± 1.7%) were reduced (P < .05). Multiple regression revealed ΔHVR and exercise VE at altitude as significant predictors of HC% (adjusted r(2) = 0.913; P = 0.003).

CONCLUSIONS

Ventilatory acclimatisation occurred during a 2 wk altitude training camp in elite cyclists and a higher HVR was associated with better performance at altitude, relative to sea level. These results suggest that ventilatory acclimatisation is beneficial for cycling performance at altitude.

Physiological and perceptual responses to incremental exercise testing in healthy men: effect of exercise test modality

In a randomized cross-over study of 15 healthy men aged 20–30 years, we compared physiological and perceptual responses during treadmill and cycle exercise test protocols matched for increments in work rate — the source of increased locomotor muscle metabolic and contractile demands. The rates of O2 consumption and CO2 production were higher at the peak of treadmill versus cycle testing (p ≤ 0.05). Nevertheless, work rate, minute ventilation, tidal volume (VT), breathing frequency (fR), inspiratory capacity (IC), inspiratory reserve volume (IRV), tidal esophageal (Pes,tidal) and transdiaphragmatic pressure swings (Pdi,tidal), peak expiratory gastric pressures (Pga,peak), the root mean square of the diaphragm electromyogram (EMGdi,rms) expressed as a percentage of maximum EMGdi,rms (EMGdi,rms%max), and dyspnea ratings were similar at the peak of treadmill versus cycle testing (p > 0.05). Ratings of leg discomfort were higher at the peak of cycle versus treadmill exercise (p ≤ 0.05), even though peak O2 consumption was lower during cycling. Oxygen consumption, CO2 production, minute ventilation, fR, Pes,tidal, Pdi,tidal and Pga,peak were higher (p ≤ 0.05), while VT, IC, IRV, EMGdi,rms%max, and ratings of dyspnea and leg discomfort were similar (p > 0.05) at all or most submaximal work rates during treadmill versus cycle exercise. Our findings highlight important differences (and similarities) in physiological and perceptual responses at maximal and submaximal work rates during incremental treadmill and cycle exercise testing protocols. The lack of effect of exercise test modality on peak work rate advocates for the use of this readily available parameter to optimize training intensity determination, regardless of exercise training mode.

Quantifying the shape of maximal expiratory flow-volume curves in healthy humans and asthmatic patients

Differences in the absolute flow and volume of maximal expiratory flow-volume (MEFV) curves have been studied extensively in health and disease. However, the shapes of MEFV curves have received less attention. We questioned if the MEFV curve shape was associated with (i) expiratory flow limitation (EFL) in health and (ii) changes in bronchial caliber in asthmatics. Using the slope-ratio (SR) index, we quantified MEFV curve shape in 84 healthy subjects and 8 matched asthmatics. Healthy subjects performed a maximal exercise test to assess EFL. Those with EFL during had a greater SR (1.15 ± 0.20 vs. 0.85 ± 0.20, p<0.05) yet, there was no association between maximal oxygen consumption and SR (r=0.14, p>0.05). Asthmatics average SR was greater than the healthy subjects (1.35 ± 0.03 vs. 0.90 ± 0.11, p<0.05), but there were no differences when bronchial caliber was manipulated. In conclusion, a greater SR is related to EFL and this metric could aid in discriminating between groups known to differ in the absolute size of MEFV curves.