Prediction of maximal oxygen uptake from submaximal ratings of perceived exertion and heart rate during a continuous exercise test: the efficacy of RPE 13

This study assessed the utility of a single, continuous exercise protocol in facilitating accurate estimates of maximal oxygen uptake ( [(V)\dot] \textO ₂ \dot{V} {\text{O}}_{ 2} max) from submaximal heart rate (HR) and the ratings of perceived exertion (RPE) in healthy, low-fit women, during cycle ergometry. Eleven women estimated their RPE during a continuous test (1 W 4 s⁻¹) to volitional exhaustion (measured [(V)\dot] \textO ₂ \dot{V} {\text{O}}_{ 2} max). Individual gaseous exchange thresholds (GETs) were determined retrospectively. The RPE and HR values prior to and including an RPE 13 and GET were extrapolated against corresponding oxygen uptake to a theoretical maximal RPE (20) and peak RPE (19), and age-predicted HRmax, respectively, to predict [(V)\dot] \textO ₂ \dot{V} {\text{O}}_{ 2} max. There were no significant differences (P > 0.05) between measured (30.9 ± 6.5 ml kg⁻¹ min⁻¹) and predicted [(V)\dot] \textO ₂ \dot{V} {\text{O}}_{ 2} max from all six methods. Limits of agreement were narrowest and intraclass correlations were highest for predictions of [(V)\dot] \textO ₂ \dot{V} {\text{O}}_{ 2} max from an RPE 13 to peak RPE (19). Prediction of [(V)\dot] \textO ₂ \dot{V} {\text{O}}_{ 2} max from a regression equation using submaximal HR and work rate at an RPE 13 was also not significantly different to actual [(V)\dot] \textO ₂ \dot{V} {\text{O}}_{ 2} max (R ²  = 0.78, SEE = 3.42 ml kg⁻¹ min⁻¹, P > 0.05). Accurate predictions of [(V)\dot] \textO ₂ \dot{V} {\text{O}}_{ 2} max may be obtained from a single, continuous, estimation exercise test to a moderate intensity (RPE 13) in low-fit women, particularly when extrapolated to peak terminal RPE (RPE₁₉). The RPE is a valuable tool that can be easily employed as an adjunct to HR, and provides supplementary clinical information that is superior to using HR alone.     

Effect of lower body compression garments on submaximal and maximal running performance in cold (10°C) and hot (32°C) environments

No previous studies have investigated the effect of lower body compression garments (CG) on running performance in the heat. This study tested the hypothesis that CG would negatively affect running performance in the heat by comparing CG and non-CG conditions for running performance and physiological responses in hot and cold conditions. Ten male recreational runners (29.0 ± 10.0 years, [(V)\dot]\textO ₂ \dot{V}{\text{O}}_{ 2} max: 58.7 ± 2.7 ml kg⁻¹ min⁻¹) performed four treadmill tests consisting of 20-min running at first ventilatory threshold followed by a run to exhaustion at [(V)\dot]\textO ₂ \dot{V}{\text{O}}_{ 2} max velocity in four conditions: 10°C with CG, 10°C without CG, 32°C with CG, and 32°C without CG (randomised, counterbalanced order). Time to exhaustion (TTE), skin and rectal temperature, [(V)\dot]\textO ₂ \dot{V}{\text{O}}_{ 2} , heart rate and rating of perceived exertion (RPE) were compared between CG and non-CG conditions at each environmental temperature. TTE was not significantly different between the CG and non-CG conditions at 10°C (158 ± 74 vs. 148 ± 73 s) and 32°C (115 ± 40 vs. 97 ± 33 s); however, there was a small (0.15) and moderate effect size (0.48), respectively, suggestive of an improvement in TTE with CG. Lower limb skin temperature was 1.5°C higher at 10°C with CG (P < 0.05), but no significant differences in other physiological variables, including rectal temperature, were observed between garment conditions. Interestingly, RPE was lower (P < 0.05) during submaximal running at 32°C with CG (13.8 ± 2.0) compared with non-CG (14.5 ± 2.7). It was concluded that CG had no adverse effects on running performance in hot conditions.     

Critical power in adolescents: physiological bases and assessment using all-out exercise

This study examined whether critical power (CP) in adolescents: (1) provides a landmark for maximal steady-state exercise; and (2) can be determined using ‘all-out’ exercise. Nine active 14–15 year olds (6 females, 3 males) performed five cycling tests: (1) a ramp test to determine [(V)\dot]\textO_2 \textpeak \dot{V}{\text{O}}_{{2\,{\text{peak}}}} ; (2) up to four constant power output tests to determine CP; (3–4) constant power output exercise 10% above and 10% below CP; and (5) a 3 min all-out cycle test to establish the end power (EP) at 90 and 180 s of exercise. All participants completed 30 min of exercise below CP and were characterized by steady-state blood lactate and [(V)\dot]\textO₂ {\dot{V}\text{O}}_{2} profiles. In contrast, time to exhaustion during exercise above CP was 15.0 ± 7.0 min and characterized by an inexorable rise in blood lactate and a rise, stabilization (~91% [(V)\dot]\textO_2 \textpeak {\dot{V}\text{O}}_{{2\,{\text{peak}}}} ) and fall in [(V)\dot]\textO₂ {\dot{V}\text{O}}_{2} (~82% [(V)\dot]\textO_2 \textpeak {\dot{V}\text{O}}_{{2\,{\text{peak}}}} ) prior to exhaustion. Eight out of nine participants completed the 3 min test and their EPs at 90 s (148 ± 29 W) and 180 s (146 ± 30 W) were not different from CP (146 ± 27 W) (P = 0.98). The typical error of estimates for establishing CP using EP at 90 s or 180 s of the 3 min test were 25 W (19.7% CV) and 25 W (19.6% CV), respectively. CP in active adolescence provides a valid landmark for maximal steady-state exercise, although its estimation on an individual level using the 3 min all-out test may be of limited value.     

Prediction of peak oxygen uptake from age and power output at RPE 15 in obese women

The purpose of this study was to develop a simple, convenient and indirect method for predicting peak oxygen uptake ( [(V)\dot]\textO_2\textpeak \dot{V}{\text{O}}_{{2{\text{peak}}}} ) from a sub-maximal graded exercise test (GXT), in obese women. Thirty obese women performed GXT to volitional exhaustion. During GXT, oxygen uptake and the power at RPE 15 ( P_{\textRPE  15} P_{{{\text{RPE}}\;15}} ) were measured, and [(V)\dot]\textO_2\textpeak \dot{V}{\text{O}}_{{2{\text{peak}}}} was determined. Following assessment of the relationships between [(V)\dot]\textO_2\textpeak \dot{V}{\text{O}}_{{2{\text{peak}}}} and P_{\textRPE  15} P_{{{\text{RPE}}\;15}} , age, height and mass were made available in a stepwise multiple regression analysis with [(V)\dot]\textO_2\textpeak \dot{V}{\text{O}}_{{2{\text{peak}}}} as the dependent variable. The equation to predict [(V)\dot]\textO_2\textpeak \dot{V}{\text{O}}_{{2{\text{peak}}}} was:

Physiological and perceptual responses to Nordic walking in obese middle-aged women in comparison with the normal walk

This study aimed to compare physiological and perceptual responses to Nordic walking (NW) in obese women to those of walking (W), and to assess if these responses were modified by a learning period of NW technique. Eleven middle-aged obese women completed exercise trials (5 min each) at 4 km/h, inclinations of −5, 0 and +5%, with and without poles. Ventilation ( \mathop V^._\textE ), \left( {\mathop V\limits^{.}}_{\text{E} } \right), oxygen consumption ([(V)\dot]_\textO\text2)(\dot{V}_{{{\text{O}}_{{\text{2}}}}}) energy cost (EC), heart rate (HR), rating of perceived exertion (RPE) and cycle length were measured before and after a 4-week learning period (12 sessions). \mathop V^._\textE ,[(V)\dot]_\textO\text2 , {\mathop V\limits^{.}}_{\text{E} } ,\dot{V}_{{{\text{O}}_{{\text{2}}}}} , EC, HR and cycle length were significantly higher (P < 0.001) during NW trials than W trials. RPE was significantly diminished (pole × inclination interaction, P = 0.031) when using NW poles compared to W uphill. Significant pole × inclination interactions were observed for [(V)\dot]_\textO\text2 \dot{V}_{{{\text{O}}_{{\text{2}}}}} (P = 0.022) and EC (P = 0.022), whereas significant pole × time interaction was found for EC (P = 0.043) and RPE (P = 0.039). Our results confirmed that use of NW poles increased physiological responses at a given speed but decreased RPE in comparison with W during inclined level. Moreover, this is the first study showing that a learning period of NW technique permitted to enhance the difference between EC with NW poles versus the W condition and to decrease the RPE when using NW poles. Thus, although it requires a specific learning of the technique, the NW might be considered like an attractive physical activity with an important public health application.     

Correspondences between continuous and intermittent exercises intensities in healthy prepubescent children

The aim of this article is to determine correspondences between three levels of continuous and intermittent exercise (CE and IE, respectively) in terms of steady-state oxygen uptake ([(V)\dot]\textO _2 \textSS ) (\dot{V}{\text{O}}_{{ 2\,{\text{SS}}}} ) and heart rate (HR) in children. Fourteen healthy children performed seven exercises on a treadmill: one graded test for the determination of maximal aerobic speed (MAS), three CE at 60, 70 and 80% of MAS (CE60, CE70 and CE80) and three IE (alternating 15 s of exercise intercepted with 15 s of passive recovery) at 90, 100 and 110% of MAS (IE90, IE100 and IE110). Mean [(V)\dot]\textO _2 \textSS \dot{V}{\text{O}}_{{ 2\,{\text{SS}}}} and mean HR were determined for both continuous and intermittent exercises. For comparison, three associations were designed: CE60 versus IE90, CE70 versus IE100 and CE80 versus IE110. No [(V)\dot]\textO _2 \textSS \dot{V}{\text{O}}_{{ 2\,{\text{SS}}}} difference was observed for CE60 versus IE90 and CE70 versus IE100 whereas a significant difference (P < 0.01) was found for CE80 versus IE110 (1.36 ± 0.45 vs. 1.19 ± 0.38 L min⁻¹, respectively). Significant linear regressions were found for the three CE versus IE associations for [(V)\dot]\textO _2 \textSS \dot{V}{\text{O}}_{{ 2\,{\text{SS}}}} (0.60 < r ² < 0.99, P < 0.05). For the three associations, mean HR presented no significant difference. Only one significant relation was found for CE80 versus IE110 association (r2 = 0.49, P < 0.05). Correspondences between CE and IE intensities are possible in terms of [(V)\dot]\textO _2 \textSS \dot{V}{\text{O}}_{{ 2\,{\text{SS}}}} whatever the level of exercise; even if for high intensities, [(V)\dot]\textO _2 \textSS \dot{V}{\text{O}}_{{ 2\,{\text{SS}}}} was higher during CE. These results demonstrated that it is possible to diversify the exercise modality while conserving exercise individualization.     

The validity and reliability of predicting maximal oxygen uptake from a treadmill-based sub-maximal perceptually regulated exercise test

The purpose of this study was to determine for the first time whether [(V)\dot]\textO _2max {\dot{V}}{\text{O}}_{ 2\hbox{max}} could be predicted accurately and reliably from a treadmill-based perceptually regulated exercise test (PRET) incorporating a safer and more practical upper limit of RPE 15 (“Hard”) than used in previous investigations. Eighteen volunteers (21.7 ± 2.8 years) completed three treadmill PRETs (each separated by 48 h) and one maximal graded exercise test. Participants self-regulated their exercise at RPE levels 9, 11, 13 and 15 in a continuous and incremental fashion. Oxygen uptake ( [(V)\dot]\textO ₂ ) \left( {{\dot{V}}{\text{O}}_{ 2} } \right) was recorded continuously during each 3 min bout. [(V)\dot]\textO₂ {\dot{V}}{\text{O}}_{2} values for the RPE range 9–15 were extrapolated to RPE₁₉ and RPE₂₀ using regression analysis to predict individual [(V)\dot]\textO_2max {\dot{V}}{\text{O}}_{2\hbox{max}} scores. The optimal limits of agreement (LoA) between actual (48.0 ± 6.2 ml kg⁻¹ min⁻¹) and predicted scores were −0.6 ± 7.1 and −2.5 ± 9.4 ml^.kg⁻¹ min⁻¹ for the RPE₂₀ and RPE₁₉ models, respectively. Reliability analysis for the [(V)\dot]\textO_2max {\dot{V}}{\text{O}}_{2\hbox{max}} predictions yielded LoAs of 1.6 ± 8.5 (RPE₂₀) and 2.7 ± 9.4 (RPE₁₉) ml kg⁻¹ min⁻¹ between trials 2 and 3. These findings demonstrate that (with practice) a novel treadmill-based PRET can yield predictions of [(V)\dot]\textO_2max {\dot{V}}{\text{O}}_{2\hbox{max}} that are acceptably reliable and valid amongst young, healthy, and active adults.     

Kinetics of VO2 limb blood flow and regional muscle deoxygenation in young adults during moderate intensity, knee-extension exercise

The kinetics of pulmonary O₂ uptake ( [(V)\dot]\textO _2 \textp ), \left( {\dot{V}{{{\text{O}}_{{ 2\,{\text{p}}}} }} } \right), limb blood flow (LBF) and deoxygenation (ΔHHb) of the vastus lateralis (VL) and vastus medialis (VM) muscles during the transition to moderate-intensity knee-extension exercise (MOD) was examined. Seven males (27 ± 5 years; mean ± SD) performed repeated step transitions (n = 4) from passive exercise to MOD. Breath by breath [(V)\dot]\textO _2 \textp , \dot{V}{{{\text{O}}_{{ 2\,{\text{p}}}} }} , femoral artery LBF, and VL and VM muscle ∆HHb were measured, respectively, by mass spectrometer and volume turbine, Doppler ultrasound and near-infrared spectroscopy. Phase 2 [(V)\dot]\textO _2 \textp , \dot{V}{{{\text{O}}_{{ 2\,{\text{p}}}} }} , LBF, and ∆HHb data were fit with a mono-exponential model. The time constant (τ) of the [(V)\dot]\textO _2 \textp \dot{V}{{{\text{O}}_{{ 2\,{\text{p}}}} }} and LBF response were not different ( t[(V)\dot]\textO _2 \textp , \tau \dot{V}{{{\text{O}}_{{ 2\,{\text{p}}}} }} , 24 ± 6 s; τLBF, 23 ± 8 s). The ∆HHb response did not differ between VL and VM in amplitude (VL 6.97 ± 4.22 a.u.; VM 7.24 ± 3.99 a.u.), time delay (∆HHb_TD: VL 17 ± 2 s; VM 15 ± 1 s), time constant (τ∆HHb: VL 11 ± 6 s; VM 13 ± 4 s), or effective time constant [τ′∆HHb (= ∆HHb_TD + τ∆HHb): VL 28 ± 7 s; VM 28 ± 4 s]. Adjustments in ∆HHb in VL and VM depict a similar balance of regional O₂ delivery and utilization within the quadriceps muscle group. The τ′∆HHb and t[(V)\dot]\textO _2 \textp \tau \dot{V}{{{\text{O}}_{{ 2\,{\text{p}}}} }} were similar, however, the ∆HHb displayed an “overshoot” relative to the steady-state levels reflecting a slower alteration of microvascular blood flow (O₂ delivery) relative to O₂ utilization, necessitating a greater reliance on O₂ extraction.     

Pulmonary oxygen uptake and muscle deoxygenation kinetics during recovery in trained and untrained male adolescents

Previous studies have demonstrated faster pulmonary oxygen uptake ( [(V)\dot]\textO₂ \dot{V}{\text{O}}_{2} ) kinetics in the trained state during the transition to and from moderate-intensity exercise in adults. Whilst a similar effect of training status has previously been observed during the on-transition in adolescents, whether this is also observed during recovery from exercise is presently unknown. The aim of the present study was therefore to examine [(V)\dot]\textO₂ \dot{V}{\text{O}}_{2} kinetics in trained and untrained male adolescents during recovery from moderate-intensity exercise. 15 trained (15 ± 0.8 years, [(V)\dot]\textO_2max \dot{V}{\text{O}}_{2\max} 54.9 ± 6.4 mL kg⁻¹ min⁻¹) and 8 untrained (15 ± 0.5 years, [(V)\dot]\textO_2max \dot{V}{\text{O}}_{2\max } 44.0 ± 4.6 mL kg⁻¹ min⁻¹) male adolescents performed two 6-min exercise off-transitions to 10 W from a preceding “baseline” of exercise at a workload equivalent to 80% lactate threshold; [(V)\dot]\textO₂ \dot{V}{\text{O}}_{2} (breath-by-breath) and muscle deoxyhaemoglobin (near-infrared spectroscopy) were measured continuously. The time constant of the fundamental phase of [(V)\dot]\textO₂ \dot{V}{\text{O}}_{2} off-kinetics was not different between trained and untrained (trained 27.8 ± 5.9 s vs. untrained 28.9 ± 7.6 s, P = 0.71). However, the time constant (trained 17.0 ± 7.5 s vs. untrained 32 ± 11 s, P < 0.01) and mean response time (trained 24.2 ± 9.2 s vs. untrained 34 ± 13 s, P = 0.05) of muscle deoxyhaemoglobin off-kinetics was faster in the trained subjects compared to the untrained subjects. [(V)\dot]\textO₂ \dot{V}{\text{O}}_{2} kinetics was unaffected by training status; the faster muscle deoxyhaemoglobin kinetics in the trained subjects thus indicates slower blood flow kinetics during recovery from exercise compared to the untrained subjects.     

Estimates of ventilation from measurements of rib cage and abdominal distances: a portable device

To validate a new device designed to measure ventilation ( [(V)\dot]_\textE ), \left( {\dot{V}_{\text{E}} } \right), tidal volume (V _T), inspiratory time (T _I), and expiratory time (T _E) during daily life activities. The anteroposterior displacement of the rib cage and abdomen and the axial displacements of the chest wall and the spine were measured using two pairs of magnetometers. [(V)\dot]_\textE \dot{V}_{\text{E}} was estimated from these four signals, and was simultaneously measured using a spirometer. A total of 707, 732, and 1,138 breaths were analyzed in sitting, standing, and exercise conditions, respectively. We compared [(V)\dot]_\textE \dot{V}_{\text{E}} , V _T, T _I, and, T _E measured by magnetometers ( [(V)\dot]_{\textE  \textmag} \dot{V}_{{{\text{E}}\;{\text{mag}}}} , V _{T mag}, T _{I mag}, and T _{E mag}) with [(V)\dot]_\textE \dot{V}_{\text{E}} , V _T, T _I, and T _E measured by a spirometer ( [(V)\dot]_{\textE  \textspiro} \dot{V}_{{{\text{E}}\;{\text{spiro}}}} , V _{T spiro}, T _{I spiro}, and T _{E spiro}, respectively). For pooled data [(V)\dot]_{\textE  \textmag} \dot{V}_{{{\text{E}}\;{\text{mag}}}} , V _{T mag}, T _{I mag}, and T _{E mag} were significantly correlated (p < 0.001) with [(V)\dot]_{\textE  \textspiro} \dot{V}_{{{\text{E}}\;{\text{spiro}}}} , V _{T spiro}, T _{I spiro}, and T _{E spiro} in sitting and standing positions and during the walking exercise. The mean differences, between [(V)\dot]_{\textE  \textmag} \dot{V}_{{{\text{E}}\;{\text{mag}}}} , and [(V)\dot]_{\textE  \textspiro} \dot{V}_{{{\text{E}}\;{\text{spiro}}}} for the group, were 10.44, 10.74, and 12.06% in sitting, standing, and exercise conditions, respectively. These results demonstrate the capacity of this new device to measure [(V)\dot]_\textE \dot{V}_{\text{E}} with reasonable accuracy in sitting, standing, and exercise conditions.     

Oxygen uptake, cardiac output and muscle deoxygenation at the onset of moderate and supramaximal exercise in humans

[(V)\dot]\textO₂ \dot{V}{\text{O}}_{2} , [(Q)\dot] \dot{Q} and muscular deoxyhaemoglobin (HHb) kinetics were determined in 14 healthy male subjects at the onset of constant-load cycling exercise performed at 80% of the ventilatory threshold (80%_VT) and at 120% of [(V)\dot]\textO_2max \dot{V}{\text{O}}_{2\max } (120%_Wmax). An innovative approach was applied to calculate the time constant (τ₂) of the primary phase of [(V)\dot]\textO₂ \dot{V}{\text{O}}_{2} and [(Q)\dot] \dot{Q} kinetics at 120%_Wmax. Data were linearly interpolated after a semilogarithmic transformation of the difference between required/steady state and measured values. Furthermore, [(V)\dot]\textO₂ \dot{V}{\text{O}}_{2} , \mathop Q ^· \mathop Q\limits^{ \cdot } and HHb data were fitted with traditional exponential models. τ₂ of [(V)\dot]\textO₂ \dot{V}{\text{O}}_{2} kinetics was longer (62.5 ± 20.9 s) at 120%_Wmax than at 80%_VT (27.8 ± 10.4 s). The τ₂ of [(Q)\dot] \dot{Q} kinetics was unaffected by exercise intensity and, at 120% of [(V)\dot]\textO_2max , \dot{V}{\text{O}}_{2\max } , it was significantly faster (τ₂ = 35.7 ± 28.4 s) than that of [(V)\dot]\textO₂ \dot{V}{\text{O}}_{2} response. The time delay of HHb kinetics was shorter (4.3 ± 1.7 s) at 120%_Wmax than at 80%_VT (8.5 ± 2.6 s) suggesting a larger mismatch between O₂ uptake and delivery at 120%_Wmax. These results suggest that [(V)\dot]\textO₂ \dot{V}{\text{O}}_{2} at the onset of exercise is not regulated/limited by muscle’s O₂ utilisation and that a slower adaptation of capillary perfusion may cause the deceleration of [(V)\dot]\textO₂ \dot{V}{\text{O}}_{2} kinetics observed during supramaximal exercise.     

Short-term exercise-heat acclimation enhances skin vasodilation but not hyperthermic hyperpnea in humans exercising in a hot environment

We tested the hypothesis that short-term exercise-heat acclimation (EHA) attenuates hyperthermia-induced hyperventilation in humans exercising in a hot environment. Twenty-one male subjects were divided into the two groups: control (C, n = 11) and EHA (n = 10). Subjects in C performed exercise-heat tests [cycle exercise for ~75 min at 58% [(V)\dot]_{\textO 2 \textpeak} \dot{V}_{{{\text{O}}_{{ 2 {\text{peak}}}} }} (37°C, 50% relative humidity)] before and after a 6-day interval with no training, while subjects in EHA performed the tests before and after exercise training in a hot environment (37°C). The training entailed four 20-min bouts of exercise at 50% [(V)\dot]_{\textO 2 \textpeak} \dot{V}_{{{\text{O}}_{{ 2 {\text{peak}}}} }} separated by 10 min of rest daily for 6 days. In C, comparison of the variables recorded before and after the no-training period revealed no changes. In EHA, the training increased resting plasma volume, while it reduced esophageal temperature (T _es), heart rate at rest and during exercise, and arterial blood pressure and oxygen uptake ( [(V)\dot]_\textO2 \dot{V}_{{{\text{O}}_{2} }} ) during exercise. The training lowered the T _es threshold for increasing forearm vascular conductance (FVC), while it increased the slope relating FVC to T _es and the peak FVC during exercise. It also lowered minute ventilation ( [(V)\dot]_\textE \dot{V}_{\text{E}} ) during exercise, but this effect disappeared after removing the influence of [(V)\dot]_\textO2 \dot{V}_{{{\text{O}}_{2} }} on [(V)\dot]_\textE \dot{V}_{\text{E}} . The training did not change the slope relating ventilatory variables to T _es. We conclude that short-term EHA lowers ventilation largely by reducing metabolism, but it does not affect the sensitivity of hyperthermia-induced hyperventilation during submaximal, moderate-intensity exercise in humans.     

Effect of ramp bicycle exercise on exhaled carbon monoxide in humans

The effect of exercise on the increase of exhaled CO in smokers compared to non-smokers has not been clarified yet. In this study we compared the dynamics of exhaled CO before, during and after exercise between smokers and non-smokers. A group of 8 smokers and a group of 8 non-smokers underwent a bicycle exercise in a ramp fashion to near maximum intensity. Ventilation and gas exchange, and CO exhalation were continuously measured every 30-s before, during and after the exercise. The fraction of CO (F _CO) in the exhaled air decreased gradually, but the total amount of exhaled CO ([(V)\dot]_\textCO ) (\dot{V}_{{{\text{CO}}}} ) increased in a linear manner during the ramp exercise, and F _CO and [(V)\dot]_\textCO \dot{V}_{\text{CO}} returned to the pre-exercise level within several minutes after exercise in all subjects. A linear relationship was observed between [(V)\dot]_{\textO 2} \dot{V}_{{{\text{O}}_{ 2} }} and [(V)\dot]_\textCO , \dot{V}_{\text{CO}} , and between [(V)\dot]_\textE \dot{V}_{\text{E}} and [(V)\dot]_\textCO \dot{V}_{\text{CO}} in both the whole period of measurement and during the ramp exercise period in all subjects. However, the [(V)\dot]_\textCO \dot{V}_{\text{CO}} at 0 W, the peak [(V)\dot]_\textCO \dot{V}_{\text{CO}} and the slope coefficients in the regression equation between [(V)\dot]_\textCO \dot{V}_{\text{CO}} and [(V)\dot]_{\textO 2} , \dot{V}_{{{\text{O}}_{ 2} }} , and between [(V)\dot]_\textCO \dot{V}_{\text{CO}} and [(V)\dot]_\textE \dot{V}_{\text{E}} in the ramp exercise as well as the entire periods of measurement were significantly higher in smokers compared with those in non-smokers, and these were correlated with the number of cigarettes smoked per day. It was concluded that CO exhalation increases linearly with the increase of [(V)\dot]_{\textO 2} \dot{V}_{{{\text{O}}_{ 2} }} and [(V)\dot]_\textE \dot{V}_{\text{E}} during exercise, and habitual smoking shifts these relationships upward depending on the number of cigarettes smoked daily.     

Energetics of karate (<Emphasis Type="Italic">kata</Emphasis> and <Emphasis Type="Italic">kumite</Emphasis> techniques) in top-level athletes

Breath-by-breath O₂ uptake ( [(V)\dot]_\textO2 \dot{V}_{{{\text{O}}_{2} }} , L min⁻¹) and blood lactate concentration were measured before, during exercise, and recovery in six kata and six kumite karate Word Champions performing a simulated competition. [(V)\dot]_{\textO 2 \textmax} , \dot{V}_{{{\text{O}}_{{ 2 {\text{max}}}} }} , maximal anaerobic alactic, and lactic power were also assessed. The total energy cost ( V_{\textO 2 \textTOT} , V_{{{\text{O}}_{{ 2 {\text{TOT}}}} }} , mL kg⁻¹ above resting) of each simulated competition was calculated and subdivided into aerobic, lactic, and alactic fractions. Results showed that (a) no differences between kata and kumite groups in [(V)\dot]_{\textO 2 \textmax} , \dot{V}_{{{\text{O}}_{{ 2 {\text{max}}}} }} , height of vertical jump, and Wingate test were found; (b) V_{\textO 2 \textTOT} V_{{{\text{O}}_{{ 2 {\text{TOT}}}} }} were 87.8 ± 6.6 and 82.3 ± 12.3 mL kg⁻¹ in kata male and female with a performance time of 138 ± 4 and 158 ± 14 s, respectively; 189.0 ± 14.6 mL kg⁻¹ in kumite male and 155.8 ± 38.4 mL kg⁻¹ in kumite female with a predetermined performance time of 240 ± 0 and 180 ± 0 s, respectively; (c) the metabolic power was significantly higher in kumite than in kata athletes (p ≤ 0.05 in both gender); (d) aerobic and anaerobic alactic sources, in percentage of the total, were significantly different between gender and disciplines (p < 0.05), while the lactic source was similar; (e) HR ranged between 174 and 187 b min⁻¹ during simulated competition. In conclusion, kumite appears to require a much higher metabolic power than kata, being the energy source with the aerobic contribution predominant.     

Influence of training status and exercise modality on pulmonary O2 uptake kinetics in pre-pubertal girls

The limited available evidence suggests that endurance training does not influence the pulmonary oxygen uptake ( [(V)\dot]\textO₂ \dot{V}{\text{O}}_{2} ) kinetics of pre-pubertal children. We hypothesised that, in young trained swimmers, training status-related adaptations in the [(V)\dot]\textO₂ \dot{V}{\text{O}}_{2} and heart rate (HR) kinetics would be more evident during upper body (arm cranking) than during leg cycling exercise. Eight swim-trained (T; 11.4 ± 0.7 years) and eight untrained (UT; 11.5 ± 0.6 years) girls completed repeated bouts of constant work rate cycling and upper body exercise at 40% of the difference between the gas exchange threshold and peak [(V)\dot]\textO₂ \dot{V}{\text{O}}_{2} . The phase II [(V)\dot]\textO₂ \dot{V}{\text{O}}_{2} time constant was significantly shorter in the trained girls during upper body exercise (T: 25 ± 3 vs. UT: 37 ± 6 s; P < 0.01), but no training status effect was evident in the cycle response (T: 25 ± 5 vs. UT: 25 ± 7 s). The [(V)\dot]\textO₂ \dot{V}{\text{O}}_{2} slow component amplitude was not affected by training status or exercise modality. The time constant of the HR response was significantly faster in trained girls during both cycle (T: 31 ± 11 vs. UT: 47 ± 9 s; P < 0.01) and upper body (T: 33 ± 8 vs. UT: 43 ± 4 s; P < 0.01) exercise. The time constants of the phase II [(V)\dot]\textO₂ \dot{V}{\text{O}}_{2} and HR response were not correlated regardless of training status or exercise modality. This study demonstrates for the first time that swim-training status influences upper body [(V)\dot]\textO₂ \dot{V}{\text{O}}_{2} kinetics in pre-pubertal children, but that cycle ergometry responses are insensitive to such differences.     

Performance and physiological responses during a sprint interval training session: relationships with muscle oxygenation and pulmonary oxygen uptake kinetics

The purpose of this study was to examine the cardiorespiratory and muscle oxygenation responses to a sprint interval training (SIT) session, and to assess their relationships with maximal pulmonary O₂ uptake ([(V)\dot]\textO _{2 \textp} \textmax) (\dot{V}{\text{O}}_{{ 2 {\text{p}}}} {\text{max)}} , on- and off- [(V)\dot]\textO _{2 \textp} \dot{V}{\text{O}}_{{ 2 {\text{p}}}} kinetics and muscle reoxygenation rate (Reoxy rate). Ten male cyclists performed two 6-min moderate-intensity exercises (≈90–95% of lactate threshold power output, Mod), followed 10 min later by a SIT session consisting of 6 × 30-s all out cycling sprints interspersed with 2 min of passive recovery. [(V)\dot]\textO _{2 \textp} \dot{V}{\text{O}}_{{ 2 {\text{p}}}} kinetics at Mod onset ( [(V)\dot]\textO _{2 \textp} t_\texton \dot{V}{\text{O}}_{{ 2 {\text{p}}}} \tau_{\text{on}} ) and cessation ( [(V)\dot]\textO _{2 \textp} t_\textoff \dot{V}{\text{O}}_{{ 2 {\text{p}}}} \tau_{\text{off}} ) were calculated. Cardiorespiratory variables, blood lactate ([La]_b) and muscle oxygenation level of the vastus lateralis (tissue oxygenation index, TOI) were recorded during SIT. Percentage of the decline in power output (%Dec), time spent above 90% of [(V)\dot]\textO _{2 \textp} max \dot{V}{\text{O}}_{{ 2 {\text{p}}}} { \max } (t > 90% [(V)\dot]\textO _{2 \textp} max \dot{V}{\text{O}}_{{ 2 {\text{p}}}} { \max } ) and Reoxy rate after each sprint were also recorded. Despite a low mean [(V)\dot]\textO _{2 \textp} \dot{V}{\text{O}}_{{ 2 {\text{p}}}} (48.0 ± 4.1% of [(V)\dot]\textO _{2 \textp} max \dot{V}{\text{O}}_{{ 2 {\text{p}}}} { \max } ), SIT performance was associated with high peak [(V)\dot]\textO _{2 \textp} \dot{V}{\text{O}}_{{ 2 {\text{p}}}} (90.4 ± 2.8% of [(V)\dot]\textO _{2 \textp} max \dot{V}{\text{O}}_{{ 2 {\text{p}}}} { \max } ), muscle deoxygenation (sprint ΔTOI = −27%) and [La]_b (15.3 ± 0.7 mmol l⁻¹) levels. Muscle deoxygenation and Reoxy rate increased throughout sprint repetitions (P < 0.001 for both). Except for t > 90% [(V)\dot]\textO _{2 \textp} max \dot{V}{\text{O}}_{{ 2 {\text{p}}}} { \max } versus [(V)\dot]\textO _{2 \textp} t_\textoff \dot{V}{\text{O}}_{{ 2 {\text{p}}}} \tau_{\text{off}} [r = 0.68 (90% CL, 0.20; 0.90); P = 0.03], there were no significant correlations between any index of aerobic function and either SIT performance or physiological responses [e.g., %Dec vs. [(V)\dot]\textO _{2 \textp} t_\textoff \dot{V}{\text{O}}_{{ 2 {\text{p}}}} \tau_{\text{off}} : r = −0.41 (−0.78; 0.18); P = 0.24]. Present results show that SIT elicits a greater muscle O₂ extraction with successive sprint repetitions, despite the decrease in external power production (%Dec = 21%). Further, our findings obtained in a small and homogenous group indicate that performance and physiological responses to SIT are only slightly influenced by aerobic fitness level in this population.     

No effect of skin temperature on human ventilation response to hypercapnia during light exercise with a normothermic core temperature

Hyperthermia potentiates the influence of CO₂ on pulmonary ventilation ( [(V)\dot]_\textE \dot{V}_{\text{E}} ). It remains to be resolved how skin and core temperatures contribute to the elevated exercise ventilation response to CO₂. This study was conducted to assess the influences of mean skin temperature ( [`(T)]<sub>\textSK</sub> \overline{T}_{\text{SK}} ) and end-tidal PCO<sub>2</sub> (P<sub>ET</sub>CO<sub>2</sub>) on [(V)\dot]<sub>\textE</sub> \dot{V}_{\text{E}} during submaximal exercise with a normothermic esophageal temperature (T <sub>ES</sub>). Five males and three females who were 1.76 ± 0.11 m tall (mean ± SD), 75.8 ± 15.6 kg in weight and 22.0 ± 2.2 years of age performed three 1 h exercise trials in a climatic chamber with the relative humidity (RH) held at 31.5 ± 9.5% and the ambient temperature (T <sub>AMB</sub>) maintained at one of 25, 30, or 35°C. In each trial, the volunteer breathed eucapnic air for 5 min during a rest period and subsequently cycle ergometer exercised at 50 W until T <sub>ES</sub> stabilized at ~37.1 ± 0.4°C. Once T <sub>ES</sub> stabilized in each trial, the volunteer breathed hypercapnic air twice for ~5 min with P<sub>ET</sub>CO<sub>2</sub> elevated by approximately +4 or +7.5 mmHg. The significantly (P < 0.05) different increases of P<sub>ET</sub>CO<sub>2</sub> of +4.20 ± 0.49 and +7.40 ± 0.51 mmHg gave proportionately larger increases in [(V)\dot]<sub>\textE</sub> \dot{V}_{\text{E}} of 10.9 ± 3.6 and 15.2 ± 3.6 L min<sup>−1</sup> (P = 0.001). This hypercapnia-induced hyperventilation was uninfluenced by varying the [`(T)]_\textSK \overline{T}_{\text{SK}} to three significantly different levels (P < 0.001) of 33.2 ± 1.2°C, to 34.5 ± 0.8°C to 36.4 ± 0.5°C. In conclusion, the results support that skin temperature between ~33 and ~36°C has neither effect on pulmonary ventilation nor on hypercapnia-induced hyperventilation during a light exercise with a normothermic core temperature.     

An examination of exercise mode on ventilatory patterns during incremental exercise

Both cycle ergometry and treadmill exercise are commonly employed to examine the cardiopulmonary system under conditions of precisely controlled metabolic stress. Although both forms of exercise are effective in elucidating a maximal stress response, it is unclear whether breathing strategies or ventilator efficiency differences exist between exercise modes. The present study examines breathing strategies, ventilatory efficiency and ventilatory capacity during both incremental cycling and treadmill exercise to volitional exhaustion. Subjects (n = 9) underwent standard spirometric assessment followed by maximal cardiopulmonary exercise testing utilising cycle ergometry and treadmill exercise using a randomised cross-over design. Respiratory gases and volumes were recorded continuously using an online gas analysis system. Cycling exercise utilised a greater portion of ventilatory capacity and higher tidal volume at comparable levels of ventilation. In addition, there was an increased mean inspiratory flow rate at all levels of ventilation during cycle exercise, in the absence of any difference in inspiratory timing. Exercising [(V)\dot]_\textE / [(V)\dot]\textCO₂ {{\dot{V}_{\text{E}} }/ {\dot{V}{\text{CO}}_{2} }} slope and the lowest [(V)\dot]_\textE / [(V)\dot]\textCO₂ {{\dot{V}_{\text{E}} }/ {\dot{V}{\text{CO}}_{2} }} value, was lower during cycling exercise than during the treadmill protocol indicating greater ventilatory efficiency. The present study identifies differing breathing strategies employed during cycling and treadmill exercise in young, trained individuals. Exercise mode should be accounted for when assessing breathing patterns and/or ventilatory efficiency during incremental exercise.     

Effects of aerobic fitness on oxygen uptake kinetics in heavy intensity swimming

This study aimed to characterise both the [(V)\dot]\textO₂ \dot{V}{\text{O}}_{2} kinetics within constant heavy-intensity swimming exercise, and to assess the relationships between [(V)\dot]\textO₂ \dot{V}{\text{O}}_{2} kinetics and other parameters of aerobic fitness, in well-trained swimmers. On separate days, 21 male swimmers completed: (1) an incremental swimming test to determine their maximal oxygen uptake ([(V)\dot]\textO_2max ) (\dot{V}{\text{O}}_{2\max } ) , first ventilatory threshold (VT), and the velocity associated with [(V)\dot]\textO_2max \dot{V}{\text{O}}_{2\max } (v[(V)\dot]\textO_2max ) (v\dot{V}{\text{O}}_{2\max } ) and (2) two square-wave transitions from rest to heavy-intensity exercise, to determine their [(V)\dot]\textO₂ \dot{V}{\text{O}}_{2} kinetics. All the tests involved breath-by-breath analysis of freestyle swimming using a swimming snorkel. [(V)\dot]\textO₂ \dot{V}{\text{O}}_{2} kinetics was modelled with two exponential functions. The mean values for the incremental test were 56.0 ± 6.0 ml min⁻¹ kg⁻¹, 1.45 ± 0.08 m s⁻¹; and 42.1 ± 5.7 ml min⁻¹ kg⁻¹ for [(V)\dot]\textO_2max \dot{V}{\text{O}}_{2\max } , v[(V)\dot]\textO_2max v\dot{V}{\text{O}}_{2\max } and VT, respectively. For the square-wave transition, the time constant of the primary phase (τ_p) averaged 17.3 ± 5.4 s and the relevant slow component (A′_sc) averaged 4.8 ± 2.9 ml min⁻¹ kg⁻¹ [representing 8.9% of the end-exercise [(V)\dot]\textO₂ \dot{V}{\text{O}}_{2} (%A′_sc)]. τ_p was correlated with v[(V)\dot]\textO_2max v\dot{V}{\text{O}}_{2\max } (r = −0.55, P = 0.01), but not with either [(V)\dot]\textO _{2 \textmax} \dot{V}{\text{O}}_{{ 2 {\text{max}}}} (r = 0.05, ns) or VT (r = 0.14, ns). The %A′_sc did not correlate with either [(V)\dot]\textO _{2 \textmax} \dot{V}{\text{O}}_{{ 2 {\text{max}}}} (r = −0.14, ns) or v[(V)\dot]\textO_2max v\dot{V}{\text{O}}_{2\max } (r = 0.06, ns), but was inversely related with VT (r = −0.61, P < 0.01). This study was the first to describe the [(V)\dot]\textO₂ \dot{V}{\text{O}}_{2} kinetics in heavy-intensity swimming using specific swimming exercise and appropriate methods. As has been demonstrated in cycling, faster [(V)\dot]\textO₂ \dot{V}{\text{O}}_{2} kinetics allow higher aerobic power outputs to be attained. The slow component seems to be reduced in swimmers with higher ventilatory thresholds.     

Influence of training status and exercise modality on pulmonary O<Subscript>2</Subscript> uptake kinetics in pubertal girls

The influence of training status on the oxygen uptake ( [(V)\dot]\textO ₂ \dot{V}{\text{O}}_{ 2} ) response to heavy intensity exercise in pubertal girls has not previously been investigated. We hypothesised that whilst training status-related adaptations would be evident in the [(V)\dot]\textO ₂ \dot{V}{\text{O}}_{ 2} , heart rate (HR) and deoxyhaemoglobin ([HHb]) kinetics of pubertal swimmers during both lower and upper body exercise, they would be more pronounced during upper body exercise. Eight swim-trained (T; 14.2 ± 0.7 years) and eight untrained (UT; 14.5 ± 1.3 years) girls completed a number of constant-work-rate transitions on cycle and upper body ergometers at 40% of the difference between the gas exchange threshold and peak [(V)\dot]\textO ₂ \dot{V}{\text{O}}_{ 2} . The phase II [(V)\dot]\textO ₂ \dot{V}{\text{O}}_{ 2} time constant (τ) was significantly shorter in the trained girls during both cycle (T: 21 ± 6 vs. UT: 35 ± 11 s; P < 0.01) and upper body exercise (T: 29 ± 8 vs. UT: 44 ± 8 s; P < 0.01). The [(V)\dot]\textO ₂ \dot{V}{\text{O}}_{ 2} slow component was not influenced by training status. The [HHb] τ was significantly shorter in the trained girls during both cycle (T: 12 ± 2 vs. UT: 20 ± 6 s; P < 0.01) and upper body exercise (T: 13 ± 3 vs. UT: 21 ± 7 s; P < 0.01), as was the HR τ (cycle, T: 36 ± 5 vs. UT: 53 ± 9 s; upper body, T: 32 ± 3 vs. UT: 43 ± 2; P < 0.01). This study suggests that both central and peripheral factors contribute to the faster [(V)\dot]\textO ₂ \dot{V}{\text{O}}_{ 2} kinetics in the trained girls and that differences are evident in both lower and upper body exercise.