Performance following prolonged sub-maximal cycling at optimal versus freely chosen pedal rate

It was tested whether cyclists perform better during all-out cycling following prolonged cycling at the pedal rate resulting in minimum oxygen uptake (VO₂), i.e. the energetically optimal pedal rate (OPR) rather than at the freely chosen pedal rate (FCPR). Nine trained cyclists cycled at 180 W to determine individual OPR and FCPR. Baseline performance was determined by measuring mean power output (W_5min) and peak VO₂ during 5-min all-out cycling at FCPR. Subsequently, on two separate days, the cyclists cycled 2.5 h at 180 W at OPR and FCPR, with each bout followed by a 5-min all-out trial. FCPR was higher (P < 0.05) than OPR at 180 W (95 ± 7 and 73 ± 11 rpm, respectively). During the prolonged cycling, VO₂, heart rate (HR), and rate of perceived exertion (RPE) were 7–9% higher (P < 0.05) at FCPR than at OPR and increased (P < 0.05) 2–21% over time. During all-out cycling following prolonged cycling at OPR and FCPR, W_5min was 8 and 10% lower (P < 0.05) than at baseline, respectively. Peak VO₂ was lower (P < 0.05) than at baseline only after FCPR. The all-out trial power output was reduced following 2.5 h of cycling at 180 W at both OPR and FCPR. However, this aspect of performance was similar between the two pedal rates, despite a higher physiological load (i.e. VO₂, HR, and RPE) at FCPR during prolonged cycling. Still, a reduced peak VO₂ only occurred after cycling at FCPR. Therefore, during prolonged sub-maximal cycling, OPR is at least as advantageous as FCPR for performance optimization in subsequent all-out cycling.     

Peak anaerobic power in patients with COPD: gender related differences

The aim of the study was to investigate peak anaerobic power during all-out exercise in patients with COPD. Twenty patients (ten women, ten men) [FEV₁ = 50.5 (7.6)% of predicted] and 11 healthy subjects (six women, five men) performed: (1) three maximal sprints on a cycle ergometer to measure peak anaerobic power (P _max) and optimal velocity (V _opt), (2) assessment of whole-body composition by dual-energy X-ray absorptiometry (DEXA) and (3) assessment of mean habitual daily energy expenditure (MHDEE). P _max was 30% lower in COPD than in healthy subjects [22.9 (7.1) vs. 32.8 (5.6) W kg⁻¹ _{legs FFM}, P < 0.001]. Nevertheless, V _opt was similar in both series. In COPD, P _max was lower in women than in men [21.4 (7.7) vs. 23.8(6.4) W kg⁻¹ _{legs FFM}, P < 0.05]. V _opt was lower in women than in COPD men [72.6 (11.3) vs. 89.3 (13.8) rpm, P < 0.05]. MHDEE was lower in COPD than in healthy subjects [8019 (1254) vs. 9093 (1660) kJ day⁻¹]. In COPD, MHDEE was lower in women than in men (P < 0.001). This study demonstrates that in COPD patients, the decrease in peak anaerobic power could play a role in their specific muscular dysfunction. Considerable differences were observed in peripheral muscle function, body composition and MHDEE between women and men. The skeletal muscle of women and men may therefore adapt to COPD in different ways.     

Validity of the two-parameter model in estimating the anaerobic work capacity

The curvature of the power–time (P–t) relationship (W′) has been suggested to be constant when exercising above critical power (CP) and to represent the anaerobic work capacity (AWC). The aim of this study was to compare W′ to (1) the total amount of work performed above CP (W _90s′) and (2) the AWC, both determined from a 90s all-out fixed cadence test. Fourteen participants (age 30.5±6.5 years; body mass 67.8±10.3 kg), following an incremental VO_2max ramp protocol, performed three constant load exhaustion tests set at 103±3, 97±3 and 90±2% P-VO_2max to calculate W′ from the P–t relationship. Two 90s all-out efforts were also undertaken to determine W _90s′ (power output—time integral above CP) and AWC (power output—time integral above the power output expected from the measured VO₂). W′ (13.6±1.3 kJ) and W _90s′ (13.9±1.1 kJ; P=0.96) were not significantly different but were lower than AWC (15.9±1.2 kJ) by 24% (P=0.03) and 17%, respectively (P=0.04). All these variables were correlated (P<0.001) but great extents of disagreement were reported (0.2±6.4 kJ between W′ and W _90s′, 2.3±7.2 kJ between W′ and AWC, and 2.1±4.3 kJ between W _90s′ and AWC). The underestimation of AWC from both W′ and W _90s′ can be explained by the aerobic inertia not taking into consideration when determining the two latter variables. The low extents of agreement between W′, W _90s′ and AWC mean the terms should not be used interchangeably.     

Power-cadence relationship in endurance cycling

In maximal sprint cycling, the power–cadence relationship to assess the maximal power output (P _max) and the corresponding optimal cadence (C _opt) has been widely investigated in experimental studies. These studies have generally reported a quadratic power–cadence relationship passing through the origin. The aim of the present study was to evaluate an equivalent method to assess P _max and C _opt for endurance cycling. The two main hypotheses were: (1) in the range of cadences normally used by cyclists, the power–cadence relationship can be well fitted with a quadratic regression constrained to pass through the origin; (2) P _max and C _opt can be well estimated using this quadratic fit. We tested our hypothesis using a theoretical and an experimental approach. The power–cadence relationship simulated with the theoretical model was well fitted with a quadratic regression and the bias of the estimated P _max and C _opt was negligible (1.0 W and 0.6 rpm). In the experimental part, eight cyclists performed an incremental cycling test at 70, 80, 90, 100, and 110 rpm to yield power–cadence relationships at fixed blood lactate concentrations of 3, 3.5, and 4 mmol L⁻¹. The determined power outputs were well fitted with quadratic regressions (R ² = 0.94–0.96, residual standard deviation = 1.7%). The 95% confidence interval for assessing individual P _max and C _opt was ±4.4 W and ±2.9 rpm. These theoretical and experimental results suggest that P _max, C _opt, and the power–cadence relationship around C _opt could be well estimated with the proposed method.     

Effects of prolonged cycle ergometer exercise on maximal muscle power and oxygen uptake in humans

Summary The mechanical power (W_tot, W·kg^–1) developed during ten revolutions of all-out periods of cycle ergometer exercise (4–9 s) was measured every 5–6 min in six subjects from rest or from a baseline of constant aerobic exercise [50%–80% of maximal oxygen uptake (VO_2max)] of 20–40 min duration. The oxygen uptake [VO₂ (W·kg^–1, 1 ml O₂ = 20.9 J)] and venous blood lactate concentration ([la]_b, mM) were also measured every 15 s and 2 min, respectively. During the first all-out period, W_tot decreased linearly with the intensity of the priming exercise (W_tot = 11.9–0.25·VO₂). After the first all-out period (i greater than 5–6 min), and if the exercise intensity was less than 60% VO_2max, W_tot, VO₂ and [la]_b remained constant until the end of the exercise. For exercise intensities greater than 60% VO_2max, VO₂ and [la]_b showed continuous upward drifts and W_tot continued decreasing. Under these conditions, the rate of decrease of W_tot was linearly related to the rate of increase of V [(d W_tot/dt) (W·kg^–1·s^–1) = 5.0·10^–5 –0.20·(d VO₂/dt) (W·kg^–1·s^–1)] and this was linearly related to the rate of increase of [la]_b [(d VO₂/dt) (W·kg^–1·s^–1) = 2.310^–4 + 5.910^–5·(d [la]_b/dt) (mM·s^–1)]. These findings would suggest that the decrease of W_tot during the first all-out period was due to the decay of phosphocreatine concentration in the exercising muscles occurring at the onset of exercise and the slow drifts of VO₂ (upwards) and of W_tot (downwards) during intense exercise at constant W_tot could be attributed to the continuous accumulation of lactate in the blood (and in the working muscles).     

Effect of internal power on muscular efficiency during cycling exercise

The purpose of this study was to investigate the muscular efficiency during cycling exercise under certain total power output (P _tot) or external power output (P _ext) experimental conditions that required a large range of pedal rates from 40 to 120 rpm. Muscular efficiency estimated as a ratio of P _tot, which is sum of internal power output (P _int) and P _ext, to rate of energy expenditure above a resting level was investigated in two experiments that featured different conditions on a cycle ergometer, which were carried out at the same levels of P _tot (Exp. 1) and P _ext (Exp. 2). Each experiment consisted of three exercise tests with three levels of pedal rates (40, 80 and 120 rpm) lasting for 2–3 min of unloaded cycling followed by 4–5 min of loaded cycling. during unloaded cycling (∼430 ml min⁻¹ for 40 rpm, ∼640 ml min⁻¹ for 80 rpm, ∼1,600 ml min⁻¹ for 120 rpm) and the P _int (∼3 W for 40 rpm, ∼25 W for 80 rpm, ∼90 W for 120 rpm) in the two experiments were markedly increased with increasing pedal rates. The highest muscular efficiency was found at 80 rpm in the two experiments, whereas a remarkable reduction (19%) in muscular efficiency obtained at 120 rpm could be attributable to greater O₂ cost due to higher levels of P _int accompanying the increased pedal rates. We concluded that muscular efficiency could be affected by the differences in O₂ cost and P _int during cycling under the large range of pedal rates employed in this study.     

Analysis of sprint cross-country skiing using a differential global navigation satellite system

The purpose was to examine skiing velocities, gear choice (G2–7) and cycle rates during a skating sprint time trial (STT) and their relationships to performance, as well as to examine relationships between aerobic power, body composition and maximal skiing velocity versus STT performance. Nine male elite cross-country skiers performed three tests on snow: (1) Maximum velocity test (V _max) performed using G3 skating, (2) V _max test performed using double poling (DP) technique and (3) a STT over 1,425 m. Additional measurements of VO_2max during roller skiing and body composition using iDXA were made. Differential global navigation satellite system data were used for position and velocity and synchronized with video during STT. The STT encompassed a large velocity range (2.9–12.9 m s⁻¹) and multiple transitions (21–34) between skiing gears. Skiing velocity in the uphill sections was related to gear selection between G2 and G3. STT performance was most strongly correlated to uphill time (r = 0.92, P < 0.05), the percentage use of G2 (r = −0.72, P < 0.05), and DP V _max (r = −0.71, P < 0.05). The velocity decrease in the uphills from lap 1 to lap 2 was correlated with VO_2max (r = −0.78, P < 0.05). V _max in DP and G3 were related to percent of racing time using G3. In conclusion, the sprint skiing performance was mainly related to uphill performance, greater use of the G3 technique, and higher DP and G3 maximum velocities. Additionally, VO_2max was related to the ability to maintain racing velocity in the uphills and lean body mass was related to starting velocity and DP maximal speed.     

Effect of hyperventilation and prior heavy exercise on O2 uptake and muscle deoxygenation kinetics during transitions to moderate exercise

The effect of hyperventilation-induced hypocapnic alkalosis (HYPO) and prior heavy-intensity exercise (HVY) on pulmonary O₂ uptake ([(V)\dot]\textO _{2 \textp}) (\dot{V}{\text{O}}_{{ 2 {\text{p}}}}) kinetics were examined in young adults (n = 7) during moderate-intensity exercise (MOD). Subjects completed leg cycling exercise during (1) normal breathing (CON, P_ETCO₂ ~ 40 mmHg) and (2) controlled hyperventilation (HYPO, P_ETCO₂ ~ 20 mmHg) throughout the protocol, with each condition repeated on four occasions. The protocol consisted of two MOD transitions (MOD1, MOD2) to 80% estimated lactate threshold with MOD2 preceded by HVY (Δ50%); each transition lasted 6 min and was preceded by 20 W cycling. [(V)\dot]\textO _{2 \textp} \dot{V}{\text{O}}_{{ 2 {\text{p}}}} was measured breath-by-breath and concentration changes in oxy- and deoxy-hemoglobin/myoglobin (Δ[HHb]) of the vastus lateralis muscle were measured by near-infrared spectroscopy. Adjustment of [(V)\dot]\textO _{2 \textp} \dot{V}{\text{O}}_{{ 2 {\text{p}}}} and Δ[HHb] were modeled using a mono-exponential equation by non-linear regression. During MOD1, the phase 2 time constant (τ) for [(V)\dot]\textO _{2 \textp}  (t[(V)\dot]\textO _{2 \textp} ) \dot{V}{\text{O}}_{{ 2 {\text{p}}}} \,(\tau \dot{V}{\text{O}}_{{ 2 {\text{p}}}} ) was greater (P < 0.05) in HYPO (45 ± 24 s) than CON (28 ± 17 s). During MOD2, t[(V)\dot]\textO _{2 \textp} \tau \dot{V}{\text{O}}_{{ 2 {\text{p}}}} was reduced (P < 0.05) in both conditions (HYPO: 24 ± 7 s, CON: 20 ± 8 s). The Δ[Hb_TOT] and Δ[O₂Hb] were greater (P < 0.05) prior to and throughout MOD2. The Δ[HHb] mean response time was similar in MOD1 and MOD2, and between conditions, however, the MOD1 Δ[HHb] amplitude was greater (P < 0.05) in HYPO compared to CON, with no differences between conditions in MOD2. These findings suggest that the speeding of [(V)\dot]\textO _{2 \textp} \dot{V}{\text{O}}_{{ 2 {\text{p}}}} kinetics after prior HVY in HYPO was related, in part, to an increase in microvascular perfusion.     

Are the parameters of VO2, heart rate and muscle deoxygenation kinetics affected by serial moderate-intensity exercise transitions in a single day?

This study compared the parameter estimates of pulmonary oxygen uptake (VO_2p), heart rate (HR) and muscle deoxygenation (Δ[HHb]) kinetics when several moderate-intensity exercise transitions (MODs) were performed during a single visit versus several MODs performed during separate visits. Nine subjects (24 ± 5 years, mean ± SD) each completed two successive cycling MODs on six occasions (1-6A and 1-6B) from 20 W to a work rate corresponding to 80% estimated lactate threshold with 6 min recovery at 20 W. During one visit, subjects completed two series of three MODs (6A-F), separated by 20 min rest. VO_2p time constants (τVO_2p; 27 ± 10 s, 25 ± 12 s, 25 ± 11 s) were similar (p > 0.05) for MODs 1-6A, 1-6B and 6A-F, respectively. τVO_2p had reproducibility 95% confidence intervals (CI₉₅) of 8.3, 8.2, 4.7, 4.9 and 4.7 s when comparing single (1A vs. 2A), the average of two (1-2A vs. 3-4A), three (1-3A vs. 4-6A), four (1-2AB vs. 3-4AB) and six (1-3AB vs. 4-6AB) MODs, respectively. The effective Δ[HHb] response time (τ′Δ[HHb]) was unaffected across conditions (1-6A: 19 ± 2 s, 1-6B: 19 ± 3 s, 6A-F: 17 ± 4 s) with reproducibility CI₉₅ of 5.3, 4.5, 3.1, 2.9 and 3.3 s when a single, two, three, four and six MODs were compared, respectively. τHR was reduced in MODs 6A-F compared to 1-6A and 1-6B (23 ± 5 s, 25 ± 5 s, 27 ± 6 s, respectively). This study showed that parameter estimates of VO_2p, HR and Δ[HHb] kinetics are largely unaffected by data collection sequence, and the day-to-day reproducibility of τVO_2p and τ′Δ[HHb] estimates, as determined by the CI₉₅, was appreciably improved by averaging of at least three MODs.     

Reliability of a 5 × 6-s maximal cycling repeated-sprint test in trained female team-sport athletes

The present study examined the reliability of work and power measures during a 5 × 6-s cycle ergometer test of repeated-sprint ability. Nine, well-trained, female soccer players performed five, 5 × 6-s repeated-sprint tests on a front-access cycle ergometer on separate days. Sprints were separated by 24 s of active recovery. Absolute measures of total work done (W _tot), total peak power (PP_tot), work done during sprint 1 (W ₁) and peak power output during sprint 1 (PP₁) were recorded. Decrement scores in work done (W _dec) and peak power output (PP_dec), and fatigue indices for work done (FI _W ) and peak power (FI _P ), were calculated. Significant improvements in all of the work and power measures were observed between trial 1 and subsequent trials (P < 0.05), but no significant differences were identified between trials 2, 3, 4 and 5. The same was true for increases in the decrement scores. The coefficient of variation (CV) was established to reflect within-subject reproducibility for each variable. The CV was significantly improved by the third trial for work done (W _tot CV: trials 1–2 = 5.5%; trials 3–4 = 2.8%), peak power (PP_tot CV: trials 1–2 = 5.1%; trials 3–4 = 2.7%) and performance decrement scores (P < 0.05). The standard error of measurement (SEM) and intraclass correlation coefficient (ICC) were also calculated for each variable and expressed within 95% confidence intervals. It was concluded that two familiarisation trials are optimal for collecting reliable data from a 5 × 6-s repeated-sprint cycling test. Furthermore, due to the large variation around performance decrement it was suggested that decrement scores ought to be interpreted with caution.Electronic supplementary material Supplementary material is available in the online version of this article at and is accessible for authorized users.     

Breath-by-breath alveolar oxygen transfer at the onset of step exercise in humans: methodological implications

The effects of using different algorithms to estimate the time constant of changes in oxygen uptake at the onset of square-wave 120 W cycloergometric exercise were evaluated in seven subjects. The volume of oxygen taken up at the alveoli (VO_2Ai) was determined breath-by-breath (BB) from the volume of O₂ transferred at the mouth (VO_2mi) minus the corresponding volume changes in O₂ stores in the alveoli: VO_2Ai=VO_2mi–[V _Ai–1(FO_2Ai–FO_2Ai–1)+FO_2Ai·ΔV _Ai], where V _Ai–1 is the alveolar volume at the end of the previous breath, FO_2Ai and FO_2Ai–1 are estimated from the fractions of end-tidal O₂ in the current and previous breaths, respectively, and ΔV _Ai is the change in volume during breath i. These quantities can be measured BB, with the exception of V _Ai–1 which must be assumed. The respiratory cycle has been defined as the time elapsing between identical fractions of expiratory gas in two successive breaths. Using this approach, since FO_2Ai=FO_2Ai–1, any assumption regarding V _Ai–1 becomes unnecessary. In the present study, VO_2Ai was calculated firstly, by using this approach, and secondly by setting different V _Ai–1 values (from 0 to FRC+0.5 l, where FRC is the functional residual capacity). Values for alveolar O₂ flow (V˙O_2Ai), as calculated from the quotient of VO_2Ai divided by breath duration, were then fitted bi-exponentially. The time constant of the phase II kinetics of V˙O_2Ai (τ₂) was linearly related to V _Ai–1, increasing from 36.6 s (V _Ai–1=0) to 46.8 s (V _Ai–1=FRC+0.5 l) while τ₂ estimated using the first approach amounted to 34.3 s. We concluded that, firstly, the first approach allowed us to calculate V˙O_2A during transitions in step exercise; and secondly, when using methods wherein V _Ai–1 must be assumed, τ₂ depended on V _Ai–1. Electronic Publication     

Force-velocity relationship and maximal power on a cycle ergometer

Summary The force-velocity relationship on a Monark ergometer and the vertical jump height have been studied in 152 subjects practicing different athletic activities (sprint and endurance running, cycling on track and/or road, soccer, rugby, tennis and hockey) at an average or an elite level. There was an approximatly linear relationship between braking force and peak velocity for velocities between 100 and 200 rev · min⁻¹. The highest indices of force P₀, velocity V₀ and maximal anaerobic power (W_max) were observed in the power athletes. There was a significant relationship between vertical jump height and W_max related to body mass.     

Kinetics of skeletal muscle O2 delivery and utilization at the onset of heavy-intensity exercise in pulmonary arterial hypertension

Impaired O₂ delivery relative to O₂ demands at the onset of exercise might influence the response profile of muscle fractional O₂ extraction (≅Δ[deoxy-Hb/Mb] by near-infrared spectroscopy) either by accelerating its rate of increase or creating an “overshoot” (OS) in patients with pulmonary arterial hypertension (PAH). We therefore assessed the kinetics of O₂ uptake ( [(V)\dot]\textO₂ ), \left( {\dot{V}{\text{O}}_{2} } \right), Δ[deoxy-Hb/Mb] in the vastus lateralis, and heart rate (HR) at the onset of heavy-intensity exercise in 14 females with PAH (connective tissue disease, IPAH, portal hypertension, and acquired immunodeficiency syndrome) and 11 age- and gender-matched controls. Patients had slower [(V)\dot]\textO₂ \dot{V}{\text{O}}_{2} and HR dynamics than controls (τ [(V)\dot]\textO₂ \dot{V}{\text{O}}_{2}  = 62.7 ± 15.2 s vs. 41.0 ± 13.8 s and t ^1/2-HR = 61.3 ± 16.6 s vs. 43.4 ± 8.8 s, respectively; p < 0.01). No study participant had a significant reduction in oxyhemoglobin saturation. In OS(−) subjects (6 patients and 7 controls), the kinetics of Δ[deoxy-Hb/Mb] relative to [(V)\dot]\textO₂ \dot{V}{\text{O}}_{2} were faster in patients (p = 0.05). Larger area under the OS and slower kinetics (MRT) of the “downward” component indicated greater O₂ delivery-to-utilization mismatch in OS(+) patients versus OS(+) controls (477.4 ± 330.0 vs. 78.1 ± 65.6 a.u. and 74.6 ± 18.8 vs. 46.0 ± 17.0 s, respectively; p < 0.05). Resting pulmonary vascular resistance was higher in OS(+) than OS(−) patients (23.1 ± 12.0 vs. 10.7 ± 4.0 Woods, respectively; p < 0.05). We conclude that microvascular O₂ delivery-to-utilization inequalities slowed the rate of adaptation of aerobic metabolism at the start of heavy-intensity exercise in women with PAH.     

Muscle deoxygenation to VO₂ relationship differs in young subjects with varying τVO₂

The relationship between the adjustment of muscle deoxygenation (∆[HHb]) and phase II VO_2p was examined in subjects presenting with a range of slow to fast VO_2p kinetics. Moderate intensity VO_2p and ∆[HHb] kinetics were examined in 37 young males (24 ± 4 years). VO_2p was measured breath-by-breath. Changes in ∆[HHb] of the vastus lateralis muscle were measured by near-infrared spectroscopy. VO_2p and ∆[HHb] response profiles were fit using a mono-exponential model, and scaled to a relative % of the response (0–100%). The ∆[HHb]/∆VO_2p ratio for each individual (reflecting the matching of O₂ distribution to O₂ utilization) was calculated as the average ∆[HHb]/∆VO_2p response from 20 to 120 s during the exercise on-transient. Subjects were grouped based on individual phase II VO_2p time-constant (τVO_2p): <21 s [very fast (VF)]; 21–30 s [fast (F)]; 31–40 s [moderate (M)]; >41 s [slow (S)]. The corresponding ∆[HHb]/∆VO_2p were 0.98 (VF), 1.05 (F), 1.09 (M), and 1.22 (S). The larger ∆[HHb]/∆VO_2p in the groups with slower VO_2p kinetics resulted in the ∆[HHb]/∆VO_2p displaying a transient “overshoot” relative to the subsequent steady state level, which was progressively reduced as τVO₂ became smaller (r = 0.91). When τVO_2p > ~20 s, the rate of adjustment of phase II VO_2p appears to be mainly constrained by the matching of local O₂ distribution to muscle VO₂. These data suggest that in subjects with “slower” VO₂ kinetics, the rate of adjustment of VO₂ may be constrained by O₂ availability within the active tissues related to the matching of microvascular O₂ distribution to muscle O₂ utilization.     

Effects of age and mode of exercise on power output profiles during repeated sprints

The aim of this study was to compare power output profiles during repeated cycling and running sprints in children and adults. On two separate visits, 12 boys [11.7 (0.5) years] and 13 men [22.1 (2.9) years] performed ten consecutive 10-s sprints interspersed with 15-s recovery intervals on a non-motorised treadmill and cycle ergometer. Peak (PPO) and mean (MPO) power outputs were measured during each sprint. Capillary fingertip blood samples were drawn at rest and 3 min after the final sprint to measure lactate accumulation ([La]). PPO and MPO decreased significantly more in adults compared to children over the ten sprints irrespective of the mode of exercise (P<0.001). PPO decreased by a similar amount during running and cycling in children (–17.7 versus –14.3%, P>0.05, respectively) and adults (–43.3 versus –40.0%, P>0.05, respectively). In contrast, MPO decreased significantly more during running compared to cycling both in children (–28.9 versus –18.7%, P<0.05) and adults (–47.0 versus –36.7%, P<0.05). The greater decrease in MPO during running compared to cycling was accompanied in children by significantly higher [La] values (7.7 versus 4.1 mmol l^–1, P<0.001). In adults, blood lactate accumulation tended to be higher during running than cycling (12.7 versus 10.8 mmol l^–1, P=0.06). To conclude, adults displayed a greater decrement in power output compared to children over the ten repeated running and cycling sprints. Furthermore, children and adults experienced greater fatigue during running compared to cycling. This last result may be attributed to additional muscle recruitment during sprint running.     

Individual differences in the responses to endurance and resistance training

Large individual differences in the responsiveness of cardiorespiratory fitness (VO_2peak) to endurance training have been observed in healthy subjects. We tested the hypothesis that subjects with a poor responsiveness to endurance training might benefit from resistance training in terms of aerobic fitness. The study population consisted of sedentary healthy male and female subjects (n=91, 42±5 year) assigned to either a training (n=73) or a control group (n=18). The randomized cross-over study design included a 2-week laboratory-controlled endurance or resistance training period with a 2-month detraining period between the interventions. Large individual differences were observed in the changes of VO_2peak (ΔVO_2peak) after both the endurance (average 8±6 %, P<0.001, range −5 to +22%) and resistance training (average 4±5%, P<0.001, range −8 to +16%). The average increase in ΔVO_2peak between genders was similar after both the endurance (8±6% for both genders, P=ns) and resistance training (3±5% for males and 5±6% for females, P=ns). There was no linear relationship between the changes in VO_2peak after each training intervention (r=−.09, P=ns). On the contrary, when the study group was divided into quartiles according to the endurance training response (1±3, 6±1, 9±1, and 16±3% increase in VO_2peak), the group with the lowest response to endurance training increased VO_2peak after the resistance training intervention (ΔVO_2peak 7±5%, P<0.001). The individual responsiveness of VO_2peak to exercise training is related to the mode of training. The healthy males and females whose training response is low after endurance training seem to result in a marked improvement in their cardiorespiratory fitness by resistance training.     

Exercise with hypoventilation induces lower muscle oxygenation and higher blood lactate concentration: role of hypoxia and hypercapnia

Eight men performed three series of 5-min exercise on a cycle ergometer at 65% of normoxic maximal O₂ consumption in four conditions: (1) voluntary hypoventilation (VH) in normoxia (VH_0.21), (2) VH in hyperoxia (inducing hypercapnia) (inspired oxygen fraction [F_IO₂] = 0.29; VH_0.29), (3) normal breathing (NB) in hypoxia (F_IO₂ = 0.157; NB_0.157), (4) NB in normoxia (NB_0.21). Using near-infrared spectroscopy, changes in concentration of oxy-(Δ[O₂Hb]) and deoxyhemoglobin (Δ[HHb]) were measured in the vastus lateralis muscle. Δ[O₂Hb − HHb] and Δ[O₂Hb + HHb] were calculated and used as oxygenation index and change in regional blood volume, respectively. Earlobe blood samples were taken throughout the exercise. Both VH_0.21 and NB_0.157 induced a severe and similar hypoxemia (arterial oxygen saturation [SaO₂] < 88%) whereas SaO₂ remained above 94% and was not different between VH_0.29 and NB_0.21. Arterialized O₂ and CO₂ pressures as well as P50 were higher and pH lower in VH_0.21 than in NB_0.157, and in VH_0.29 than in NB_0.21. Δ[O₂Hb] and Δ[O₂Hb − HHb] were lower and Δ[HHb] higher at the end of each series in both VH_0.21 and NB_0.157 than in NB_0.21 and VH_0.29. There was no difference in Δ[O₂Hb + HHb] between testing conditions. [La] in VH_0.21 was greater than both in NB_0.21 and VH_0.29 but not different from NB_0.157. This study demonstrated that exercise with VH induced a lower tissue oxygenation and a higher [La] than exercise with NB. This was caused by a severe arterial O₂ desaturation induced by both hypoxic and hypercapnic effects.     

Aerobic power and peak power of elite America’s Cup sailors

Big-boat yacht racing is one of the only able bodied sporting activities where standing arm-cranking (‘grinding’) is the primary physical activity. However, the physiological capabilities of elite sailors for standing arm-cranking have been largely unreported. The purpose of the study was to assess aerobic parameters, VO_2peak and onset of blood lactate (OBLA), and anaerobic performance, torque–crank velocity and power–crank velocity relationships and therefore peak power (P _max) and optimum crank-velocity (ω_opt), of America’s Cup sailors during standing arm-cranking. Thirty-three elite professional sailors performed a step test to exhaustion, and a subset of ten grinders performed maximal 7 s isokinetic sprints at different crank velocities, using a standing arm-crank ergometer. VO_2peak was 4.7 ± 0.5 L/min (range 3.6–5.5 L/min) at a power output of 332 ± 44 W (range 235–425 W). OBLA occurred at a power output of 202 ± 31 W (61% of W_max) and VO₂ of 3.3 ± 0.4 L/min (71% of VO_2peak). The torque–crank velocity relationship was linear for all participants (r = 0.9 ± 0.1). P _max was 1,420 ± 37 W (range 1,192–1,617 W), and ω_opt was 125 ± 6 rpm. These data are among the highest upper-body anaerobic and aerobic power values reported. The unique nature of these athletes, with their high fat-free mass and specific selection and training for standing arm cranking, likely accounts for the high values. The influence of crank velocity on peak power implies that power production during on-board ‘grinding’ may be optimised through the use of appropriate gear-ratios and the development of efficient gear change mechanisms.     

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.     

Anaerobic and aerobic components during arm-crank exercise in sprint and middle-distance swimmers

Summary The purpose of this investigation was to compare anaerobic and aerobic components measured during arm exercise in sprint and middle-distance swimmers and to investigate whether the peak anaerobic power :peak aerobic power ratio (W _{an, peak} :W aer, peak) was related to specialization for the event and to performance. TheW _{an, peak} force at zero velocity (F ₀), and velocity at zero-force (₀),W _{aer, peak}, peak oxygen uptake ( O_2peak), and ventilatory threshold (Th _v ) were compared during arm exercise tests in sprint (group I,n = 8) and middle-distance (group II,n = 9) competitive male swimmers. Anaerobic indices were estimated by the force-velocity test, an anaerobic test using incremental braking forces; aerobic indices were measured during an incremental aerobic exercise test (30 W · min^–1). TheW _{an, peak} andW aer, peak were greater in group I [828 (SEM 70) W; 236 (SEM 12) W] than in group II [678 (SEM 28) W; 230 (SEM 5) W], but the differences were not significant. There were also no significant differences observed between the mean values ofF ₀, ₀, O_2peak, and Th _v . TheW _{an, peak}:W _{aer, peak}, however, was significantly higher in sprint swimmers (t = 3.08,P < 0.01). In seven of the swimmers, who had recently performed both the 100-m and 400-m front crawl, a relationship existed between their swim time and theW _{an, peak}:Waer,peak (100m:r = –0.80,P<0.05 and 400m:r=+0.75,P<0.05). In conclusion, during arm-crank exercise, we did not observe significant differences in anaerobic and aerobic components between sprint and middle-distance swimmers. However, the results of the present study demonstrated the usefulness of theW _{an, peak} :W _{aer, peak} in the physiological evaluation of swimmers as it reflects the proportion of anaerobic to aerobic systems involved in the supply of energy.