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We examined the effect of completing the final interval training session during a taper at either (i) race pace (RP) or (ii) faster than RP on 1500-m running performance and neuromuscular performance. Ten trained runners (age, 21.7 ± 3.0 years; height, 182.9 ± 7.0 cm; body mass, 73.4 ± 6.8 kg; and personal best 1500-m time, 4:17.5 ± 0:26.9 min) completed 2 conditions consisting of 7 days of regular training and a 7-day taper, separated by 3 weeks of training. In 1 condition, the taper was prescribed using prediction models based on the practices of elite British middle-distance runners, with the intensity of the final interval session being equal to 1500-m RP. The taper was repeated in the high-intensity (HI) condition, with the exception that the final interval session was completed at 115% of 1500-m RP. A 1500-m treadmill time trial and measures of maximal voluntary contraction (MVC) and rate of force development (RFD) were completed before and after regular training and tapering. Performance was most likely improved after RP (mean ± 90% confidence limits, 10.1 ± 1.6 s), and possibly beneficial after HI (4.2 ± 12.0 s). Both MVC force (p = 0.002) and RFD (p = 0.02) were improved after tapering, without differences between conditions. An RP taper based on the practices of elite middle-distance runners is recommended to improve performance in young, subelite runners. The effect of this strategy with an increase in interval intensity is highly variable and should be implemented with caution.

This study sought to establish perceptions of elite endurance athletes on the role and worth of altitude training. Elite British endurance runners were surveyed to identify the altitude and hypoxic training methods utilised, along with reasons for use, and any situational, cultural and behaviour factors influencing these. Prior to the 2012 Olympics Games, 39 athletes and 20 support staff (coaches/practitioners) completed an internet-based survey to establish differences between current practices and the accepted "best-practice". Almost all of the athletes (98%) and support staff (95%) surveyed had utilised altitude and hypoxic training, or had advised it to athletes. 75% of athletes believed altitude and hypoxia to be a "very important" factor in their training regime, with 50% of support staff believing the same. Athletes and support staff were in agreement of the methods of altitude training utilised (i.e. 'hypoxic dose' and strategy), with camps lasting 3-4 weeks at 1,500-2,500 m being the most popular. Athletes and support staff are utilising altitude and hypoxic training methods in a manner agreeing with research-based suggestions. The survey identified a number of specific challenges and priorities, which could provide scope to optimise future altitude training methods for endurance performance in these elite groups.

This study aimed to establish the effect of cycling mode and cadence on torque, external power output, and lower limb muscle activation during maximal, recumbent, isokinetic cycling. After familiarisation, twelve healthy males completed 6 × 10 s of maximal eccentric (ECC) and concentric (CON) cycling at 20, 40, 60, 80, 100, and 120 rpm with five minutes recovery. Vastus lateralis, medial gastrocnemius, rectus femoris, and biceps femoris surface electromyography was recorded throughout. As cadence increased, peak torque linearly decreased during ECC (350-248 N·m) and CON (239-117 N·m) and peak power increased in a parabolic manner. Crank angle at peak torque increased with cadence in CON (+13°) and decreased in ECC (-9.0°). At all cadences, peak torque (mean +129 N·m, range 111-143 N·m), and power (mean +871 W, range 181-1406 W), were greater during ECC compared to CON. For all recorded muscles the crank angle at peak muscle activation was greater during ECC compared to CON. This difference increased with cadence in all muscles except the vastus lateralis. Additionally, peak vastus laterallis and biceps femoris activation was greater during CON compared to ECC. Eccentric cycling offers a greater mechanical stimulus compared to concentric cycling but the effect of cadence is similar between modalities. Markers of technique (muscle activation, crank angle at peak activation and torque) were different between eccentric and concentric cycling and respond differently to changes in cadence. Such data should be considered when comparing between, and selecting cadences for, recumbent, isokinetic, eccentric and concentric cycling.

BACKGROUND: Isokinetic eccentric cycling is increasingly being utilised to examine the effect of chronic eccentric muscle training however little is known about how individuals familiarise to such a unique training modality. \ud \ud OBJECTIVE: To examine longitudinal variation in power output and lower limb muscle activation during familiarisation to maximal recumbent isokinetic eccentric cycling. \ud \ud METHODS: Twelve male volunteers, unfamiliar with eccentric cycling, completed four trials, separated by 7-10 days, each comprising 6 × 10 s maximal isokinetic eccentric efforts between 20-120 rpm. Peak power and average power output (PO), and surface electromyography (sEMG) of the rectus femoris (RF), vastus lateralis (VL), biceps femoris (BF), and medial gastrocnemius (MG) were recorded throughout. Systematic error across repeated trials was assessed using one-way ANOVA, and random error quantified using coefficient of variation (CV, %). \ud \ud RESULTS: Average PO at 60 rpm and RF activation at 20 rpm increased from trial 1-2 (p < 0.05), with no other systematic error between trials at any cadence. Across all cadences, the CV for peak PO (∼ 13%), average PO (∼ 10%), VL activation (∼ 13%) and RF activation (∼ 19%) was moderate and plateaued after one familiarisation (i.e. T2-T3). However, for BF (∼ 24%) and MG (∼ 22%) activation reliability was generally poor. For the majority of variables the reliability was best at 60 rpm. \ud \ud CONCLUSIONS: Therefore, with one familiarisation, 60 rpm is recommended to achieve moderate between-session reliability in the measurement of power output and lower limb muscle activation during recumbent, eccentric cycling.

A new Radiometer™ hemoximeter (ABL-80) has recently become available to measure carboxyhaemoglobin concentration for the optimized CO-rebreathing method (oCOR-method). Within the English Institute of Sport (EIS), hemoximeters are used in three different laboratories; therefore, precision and agreement of total haemoglobin mass (tHbmass) determination across sites is essential, and comparison to the previous model OSM-3 is desirable. Six male and one female (age 30 ± 6 years, body mass 78.1 ± 10.6 kg) undertook the oCOR-method. Venous blood (~2 ml) was sampled immediately before and at 7 min during the oCOR-method; with seven replicates from each time point simultaneously analysed on five different Radiometer™ hemoximeters [OSM-3(1), OSM-3(2), ABL-80(1), ABL-80(2) and ABL-80(3)]. There were no differences (p > 0.05) between Δ%HbCO or mean tHbmass analysed with five different hemoximeters (OSM-3(1): 886 ± 167 g; OSM-3(2): 896 ± 160 g: ABL-80(1): 904 ± 157 g; ABL-80(2): 906 ± 163 g: ABL-80(3): 906 ± 162 g). However, the Bland-Altman plot revealed that there was closer agreement between ABL-80 machines for tHbmass than for the OSM-3. The variance (i.e. % error) across replicate samples decreased as the number of samples increased, with the error derived from the 'worse-case' scenario (single samples) being 1.2 to 1.6 fold greater in the OSM-3 than the ABL-80. Although there were no differences in the average tHbmass measured with five different hemoximeters, the new ABL-80 were in better agreement with each other compared to the old OSM-3. Previously, five replicates were required to achieve a low error using the OSM-3; however, three replicates are sufficient with the ABL-80 model to produce an error of ≤ 1% in tHbmass.

The optimized carbon monoxide (CO) rebreathing method (oCOR-method) is routinely used to measure total haemoglobin mass (tHbmass). The tHbmass measure is subject to a test-retest typical error of ~2%, mostly from the precision of carboxyhaemoglobin (HbCO) measurement. We hypothesized that tHbmass would be robust to differences in the bolus of CO administered during the oCOR-method. Twelve participants (ten males and two females; age 27 ± 6 yr, height 177 ± 11 cm and mass 73.9 ± 12.1 kg) completed the oCOR-method on four occasions. Different bolus of CO were administered (LOW: 0.6 ml kg(-1); MED1: 1.0 ml kg(-1) and HIGH: 1.4 ml kg(-1)); to determine the reliability of MED1, a second trial was conducted (MED2). tHbmass was found to be significantly less from the HIGH CO bolus (776 ± 148 g) when compared to the LOW CO (791 ± 149 g) or MED1 CO (788 ± 149 g) trials. MED2 CO was 785 ± 150 g. The measurement of tHbmass is repeatable to within 0.8%, but a small and notable difference was seen when using a HIGH CO bolus (1.4 to 1.9% less), potentially due to differences in CO uptake kinetics. Previously, an improved precision of the oCOR-method was thought to require a higher bolus of CO (i.e. larger Δ%HbCO), as commercial hemoximeters only estimate %HbCO levels to a single decimal place (usually ± 0.1%). With the new hemoximeter used in this study, a bolus of 1.0 ml kg(-1) allows adequate precision with acceptable safety.

Purpose:This study examined parameters derived from both an incremental step-wise and a ramp-wise graded rowing exercise test in relation to rowing performance.Methods:Discontinuous step-wise incremental rowing to exhaustion established lactate threshold (LT), maximum oxygen consumption (VO2maxSTEP), and power associated with VO2max (W VO2max). A further continuous ramp-wise test was undertaken to derive ventilatory threshold (VT), maximum oxygen consumption (VO2maxRAMP), and maximum minute power (MMW). Results were compared with maximal 2000-m ergometer time-trial power.Results:The strongest correlation with 2000-m power was observed for MMW (r = .98, P < .001), followed by W VO2max (r = .96; P < .001). The difference between MMW and W VO2max compared with the mean of MMW/W VO2max showed a widening bias with a greater difference coincident with greater power. However, this bias was reduced when expressed as a ratio term and when a baseline VO2 was accounted for. There were no differences (P = .85) between measures of VO2maxSTEP and VO2maxRAMP; rather, the measures showed strong association (r = .97, P < .001, limits of agreement = −0.43 to 0.33 L/min). The power at LT and VT did not differ (P = .6), and a significant association was observed (r = .73, P = .001, limits of agreement = −54.3 to 20.2 W, SEE = 26.1).Conclusions:This study indicates that MMW demonstrates a strong association with ergometer rowing performance and thus may have potential as an influential monitoring tool for rowing athletes.

Prior high-intensity exercise increases the oxidative energy contribution to subsequent exercise and may enhance exercise tolerance. The potential impact of a high-intensity warm-up on competitive performance, however, has not been investigated.Purpose:To test the hypothesis that a high-intensity warm-up would speed VO2 kinetics and enhance 800-m running performance in well-trained athletes.Methods:Eleven highly trained middle-distance runners completed two 800-m time trials on separate days on an indoor track, preceded by 2 different warm-up procedures. The 800-m time trials were preceded by a 10-min self-paced jog and standardized mobility drills, followed by either 6 × 50-m strides (control [CON]) or 2 × 50-m strides and a continuous high-intensity 200-m run (HWU) at race pace. Blood [La] was measured before the time trials, and VO2 was measured breath by breath throughout exercise.Results:800-m time-trial performance was significantly faster after HWU (124.5 ± 8.3 vs CON, 125.7 ± 8.7 s, P < .05). Blood [La] was greater after HWU (3.6 ± 1.9 vs CON, 1.7 ± 0.8 mM; P < .01). The mean response time for VO2 was not different between conditions (HWU, 27 ± 6 vs CON, 28 ± 7 s), but total O2 consumed (HWU, 119 ± 18 vs CON, 109 ± 28 ml/kg, P = .05) and peak VO2 attained (HWU, 4.21 ± 0.85 vs CON, 3.91 ± 0.63 L/min; P = .08) tended to be greater after HWU.Conclusions:These data indicate that a sustained high-intensity warm-up enhances 800-m time-trial performance in trained athletes.

Purpose The effects of low-volume interval and continuous ‘all-out’ cycling, matched for total exercise duration, on mitochondrial and angiogenic cell signalling was investigated in trained individuals. Methods In a repeated measures design, 8 trained males (\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\dot{V}{\text{O}}_{{2{\text{peak}}}}$$\end{document}V˙O2peak, 57 ± 7 ml kg−1 min−1) performed two cycling exercise protocols; interval (INT, 4 × 30 s maximal sprints interspersed by 4 min passive recovery) or continuous (CON, 2 min continuous maximal sprint). Muscle biopsies were obtained before, immediately after and 3 h post-exercise. Results Total work was 53 % greater (P = 0.01) in INT compared to CON (71.2 ± 7.3 vs. 46.3 ± 2.7 kJ, respectively). Phosphorylation of AMPKThr172 increased by a similar magnitude (P = 0.347) immediately post INT and CON (1.6 ± 0.2 and 1.3 ± 0.3 fold, respectively; P = 0.011), before returning to resting values at 3 h post-exercise. mRNA expression of PGC-1α (7.1 ± 2.1 vs. 5.5 ± 1.8 fold; P = 0.007), VEGF (3.5 ± 1.2 vs. 4.3 ± 1.8 fold; P = 0.02) and HIF-1α (2.0 ± 0.5 vs. 1.5 ± 0.3 fold; P = 0.04) increased at 3 h post-exercise in response to INT and CON, respectively; the magnitude of which were not different between protocols. Conclusions Despite differences in total work done, low-volume INT and CON ‘all-out’ cycling, matched for exercise duration, provides a similar stimulus for the induction of mitochondrial and angiogenic cell signalling pathways in trained skeletal muscle.

Altitude training is commonly used by endurance athletes and coaches in pursuit of enhancement of performance on return to sea level. The purpose of the current review article was to update and evaluate recent literature relevant to the practical application of altitude training for endurance athletes. Consequently, the literature can be considered in either of two categories: performance-led investigations or mechanistic advancements/insights. Each section discusses the relevant literature and proposes future directions where appropriate.

The purpose of this study was to establish the validity of a 90-s all-out test for the estimation of maximal oxygen uptake (V.O (2max)) and submaximal aerobic ability as represented by critical power. We hypothesized that the fall in power output by the end of the 90-s all-out test (end power) would represent the exhaustion of anaerobic work capability, and as such, would correspond with the critical power. Sixteen active individuals (mean +/- SD: 30 +/- 6 years; 69.6 +/- 9.9 kg) carried out a series of tests: (i) an incremental ramp test to determine V.O (2max), (ii) three fixed-work rate trials to exhaustion to determine critical power, and (iii) two 90-s all-out tests to measure end power and peak V.O (2). End power (292 +/- 65 W) was related to (r=0.89) but was significantly higher (p

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 VO(2)). 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.

The aim of the present study was to ascertain whether the intensity of prior exercise altered the time to exhaustion at critical power (CP).Eleven participants volunteered to take part in the study (mean +/- SD: VO2max 4.1 +/- 0.5 L x min(-1); age 30.1 +/- 7.2 yr; body mass 74.6 +/- 9.1 kg) and completed three trials to exhaustion at their CP under differing prior exercise conditions: 1) a control trial (CON); 2) a trial preceded by three 60-s efforts at 110% CP (severe); and 3) a trial preceded by three 73-s efforts at 90% CP (heavy). All trials followed a 5-min baseline at 50 W.Time to exhaustion was significantly lengthened after prior heavy exercise (1071 +/- 18 s) when compared with CON (973 +/- 16 s, F = 9.53, P = 0.006). However, there was no effect on TTE after prior severe exercise (967 +/- 16 s). Oxygen deficit was significantly reduced from that in CON (3.8 +/- 0.2 L) after prior heavy (3.2 +/- 0.3 L) and prior severe exercise (3.1 +/- 0.3 L, F = 10.95, P = 0.001). Concurrently, there was a significant reduction in the magnitude of the VO2 slow component (SC) in the trials with prior exercise (197 +/- 34 and 126 +/- 19 mL x min(-1) after heavy and severe exercise, respectively) when compared with CON (223 +/- 31 mL x min(-1), F = 9.62, P = 0.006).Prior heavy exercise does appear to improve the time to exhaustion at CP by approximately 10% and is associated with a reduction in the VO2 SC. However, the reduction in the SC, with no change in performance after prior severe exercise, suggests that a reduced SC may not necessarily lead to improved TTE.

We hypothesised that the ratio between the increase in oxygen uptake and the increase in work rate (Delta VO(2)/DeltaWR) during ramp cycle exercise would be significantly related to the percentage type II muscle fibres at work rates above the gas exchange threshold (GET) where type II fibres are presumed to be active. We further hypothesised that ramp exercise at higher pedal rates, which would be expected to increase the proportional contribution of type II fibres to the total power delivered, would increase the Delta VO(2)/DeltaWR slope at work rates above the GET. Fourteen healthy subjects [four female; mean (SD): age 25 (3) years, body mass 74.3 (15.1) kg] performed a ramp exercise test to exhaustion (25 W min(-1)) at a pedal rate of 75 rev min(-1), and consented to a muscle biopsy of the vastus lateralis. Eleven of the subjects also performed two further ramp tests at pedal rates of 35 and 115 rev min(-1). The Delta VO(2)/DeltaWR slope for exerciseGET ( S(1)) was significantly correlated with VO(2) peak in ml kg(-1) min(-1) ( r=0.60; P0.05), whereas the Delta VO(2)/DeltaWR slope for exerciseGET ( S(2)) was significantly correlated to percentage type II fibres ( r=0.54; P=0.05). The ratio between the Delta VO(2)/DeltaWR slopes for exercise above and below the GET ( S(2)/ S(1)) was significantly greater at the pedal rate of 115 rev min(-1) [1.22 (0.09)] compared to pedal rates of 35 rev min(-1) [0.96 (0.02)] and 75 rev min(-1) [1.09 (0.05), ( P0.05)]. The greater increase in S(2) relative to S(1) in subjects (1) with a high percentage type II fibres, and (2) at a high pedal rate, suggests that a greater recruitment of type II fibres contributes in some manner to the "xs" VO(2) observed during ramp exercise.

The purpose of the present study was to test the hypothesis that muscle fibre type influences the oxygen uptake (.VO(2)) on-kinetic response (primary time constant; primary and slow component amplitudes) during moderate, heavy and severe intensity sub-maximal cycle exercise. Fourteen subjects [10 males, mean (SD) age 25 (4) years; mass 72.6 (3.9) kg; .VO(2peak) 47.9 (2.3) ml kg(-1) min(-1)] volunteered to participate in this study. The subjects underwent a muscle biopsy of the vastus lateralis for histochemical determination of muscle fibre type, and completed repeat "square-wave" transitions from unloaded cycling to power outputs corresponding to 80% of the ventilatory threshold (VT; moderate exercise), 50% (heavy exercise) and 70% (severe exercise) of the difference between the VT and .VO(2peak). Pulmonary .VO(2) was measured breath-by-breath. The percentage of type I fibres was significantly correlated with the time constant of the primary .VO(2) response for heavy exercise (r=-0.68). Furthermore, the percentage of type I muscle fibres was significantly correlated with the gain of the .VO(2) primary component for moderate (r=0.65), heavy (r=0.57) and severe (r=0.57) exercise, and with the relative amplitude of the .VO(2) slow component for heavy (r=-0.74) and severe (r=-0.64) exercise. The influence of muscle fibre type on the .VO(2) on-kinetic response persisted when differences in aerobic fitness and muscle capillarity were accounted for. This study demonstrates that muscle fibre type is significantly related to both the speed and the amplitudes of the .VO(2) response at the onset of constant-load sub-maximal exercise. Differences in contraction efficiency and oxidative enzyme activity between type I and type II muscle fibres may be responsible for the differences observed.

We hypothesized that a higher pedal rate (assumed to result in a greater proportional contribution of type II motor units) would be associated with an increased amplitude of the O2 uptake (V˙o 2) slow component during heavy-cycle exercise. Ten subjects (mean ± SD, age 26 ± 4 yr, body mass 71.5 ± 7.9 kg) completed a series of square-wave transitions to heavy exercise at pedal rates of 35, 75, and 115 rpm. The exercise power output was set at 50% of the difference between the pedal rate-specific ventilatory threshold and peakV˙o 2, and the baseline power output was adjusted to account for differences in the O2 cost of unloaded pedaling. The gain of the V˙o 2primary component was significantly higher at 35 rpm compared with 75 and 115 rpm (mean ± SE, 10.6 ± 0.3, 9.5 ± 0.2, and 8.9 ± 0.4 ml · min−1 · W−1, respectively; P < 0.05). The amplitude of theV˙o 2 slow component was significantly greater at 115 rpm (328 ± 29 ml/min) compared with 35 rpm (109 ± 30 ml/min) and 75 rpm (202 ± 38 ml/min) ( P < 0.05). There were no significant differences in the time constants or time delays associated with the primary and slow components across the pedal rates. The change in blood lactate concentration was significantly greater at 115 rpm (3.7 ± 0.2 mM) and 75 rpm (2.8 ± 0.3 mM) compared with 35 rpm (1.7 ± 0.4 mM) ( P < 0.05). These data indicate that pedal rate influences V˙o 2 kinetics during heavy exercise at the same relative intensity, presumably by altering motor unit recruitment patterns.

The present study examined the use of the maximal lactate steady state (MLSS) as an exercise training stimulus in moderately trained runners. Fourteen healthy individuals (12 male, 2 female; age 25 +/- 6 years, height 1.76 +/- 0.05 m, body mass 76 +/- 8 kg mean +/- SD) took part in the study. Following determination of the lactate threshold (LT), VO2max, running velocity at MLSS (vMLSS) and a control period of 4 weeks, participants were pair matched and split into two cohorts performing either continuous (CONT: 2 sessions/week at vMLSS) or intermittent treadmill running (INT: 2 sessions/week, 3-min repetitions 0.5 km . h (-1) above and below vMLSS). vMLSS increased in CONT by 8 % from 12.3 +/- 1.5 to 13.4 +/- 1.6 km . h (-1) (p < 0.05) and in INT by 5 % from 12.2 +/- 1.9 km . h (-1) to 12.9 +/- 1.9 km . h (-1) (p < 0.05). Running speed at the LT increased by 7 % in the CONT group (p < 0.05) and by 9 % in the INT group (p < 0.05). VO2max increased by 10 % in the CONT group (p < 0.05) and by 6 % in INT (p < 0.05). Two sessions per week at vMLSS are capable of eliciting improvements in the physiological responses at LT, MLSS, and VO2max in moderately trained runners.

To test the hypothesis that muscle fiber recruitment patterns influence the oxygen uptake (VO2) kinetic response, constant-load exercise was performed after glycogen depletion of specific fiber pools.After validation of protocols for the selective depletion of Type I and II muscle fibers, 19 subjects performed square-wave exercise at 80% VT (moderate) and at 50% of the difference between VT and VO2max (heavy) without any prior depleting exercise (CON), after HIGH (10 x 1-min exercise bouts at 120% VO2max), and after LOW (3 h of exercise at 30% VO2max) exercise.Differences in VO2 kinetic parameters were only observed in heavy exercise AFTER HIGH: the VO2 primary component was higher (1.75 +/- 0.12 L x min) compared with CON (1.65 +/- 0.11 L x min, P0.05), and the VO2 slow component was lower (0.18 +/- 0.03 L x min) compared with CON (0.24 +/- 0.04 L x min, P0.05).The results indicate that the VO2 response to heavy constant-load exercise can be altered by depletion of glycogen in the Type II muscle fibers, lending support to the theory that muscle fiber recruitment influences both the VO2 primary and slow component amplitudes during heavy intensity exercise.

We hypothesised that: (1) the maximal lactate steady state (MLSS), critical power (CP) and electromyographic fatigue threshold (EMG(FT)) occur at the same power output in cycling exercise, and (2) exercise above the power output at MLSS (P-MLSS) results in continued increases in oxygen uptake (VO(2)), blood lactate concentration ([La]) and integrated electromyogram (iEMG) with time. Eight healthy subjects [mean (SD) age 25 (3) years, body mass 72.1 (8.2) kg] performed a series of laboratory tests for the determination of MLSS, CP and EMG(FT). The CP was determined from four exhaustive trials of between 2 and 15 min duration. The MLSS was determined as the highest power output at which the increase in blood [La] was less than 1.0 mM across the last 20 min of a series of 30-min trials. The EMG(FT) was determined from four trials of 2 min duration at different power outputs. The surface electromyogram was recorded continuously from the vastus lateralis muscle. The CP was significantly higher than the P-MLSS [242 (25) vs. 222 (23) W; P

The aim of this study was to examine the effect of increasing the ratio of concentric to eccentric muscle activation on oxygen uptake (VO(2)) kinetics during treadmill running. Nine subjects [2 women; mean (SD) age 29 (7) years, height 1.77 (0.07) m, body mass 73.0 (7.5) kg] completed incremental treadmill tests to exhaustion at 0% and 10% gradients to establish the gradient-specific ventilatory threshold (VT) and maximal oxygen uptake (VO(2max)). Subsequently, the subjects performed repeated moderate intensity (80% of gradient-specific VT) and heavy intensity (50% of the difference between the gradient specific VT and VO(2max)) square-wave runs with the treadmill gradient set at 0% and 10%. For moderate intensity exercise, there were no significant differences between treadmill gradients for VO(2) kinetics. For heavy intensity exercise, the amplitude of the primary component of VO(2) was not significantly different between 0% and 10% treadmill gradients [mean (SEM) 2,940 (196) compared to 2,869 (156) ml x min(-1), respectively], but the amplitude of the VO(2) slow component was significantly greater at the 10% gradient [283 (43) compared to 397 (37) ml x min(-1); P < 0.05]. These results indicate that the muscle contraction regimen (i.e. the relative contribution of concentric and eccentric muscle action) significantly influences the amplitude of the VO(2) slow component.

The purpose of this study was to test the effect of oral creatine (Cr) supplementation on pulmonary oxygen uptake (V˙o 2) kinetics during moderate [below ventilatory threshold (VT)] and heavy (above VT) submaximal cycle exercise. Nine subjects (7 men; means ± SD: age 28 ± 3 yr, body mass 73.2 ± 5.6 kg, maximalV˙o 2 46.4 ± 8.0 ml · kg−1 · min−1) volunteered to participate in this study. Subjects performed transitions of 6-min duration from unloaded cycling to moderate (80% VT; 8–12 repeats) and heavy exercise (50% change; i.e., halfway between VT and maximal V˙o 2; 4–6 repeats), both in the control condition and after Cr loading, in a crossover design. The Cr loading regimen involved oral consumption of 20 g/day of Cr monohydrate for 5 days, followed by a maintenance dose of 5 g/day thereafter. V˙o 2 was measured breath by breath and modeled by using two (moderate) or three (heavy) exponential terms. For moderate exercise, there were no differences in the parameters of the V˙o 2 kinetic response between control and Cr-loaded conditions. For heavy exercise, the time-based parameters of the V˙o 2response were unchanged, but the amplitude of the primary component was significantly reduced with Cr loading (means ± SE: control 2.00 ± 0.12 l/min; Cr loaded 1.92 ± 0.10 l/min; P < 0.05) as was the end-exerciseV˙o 2 (control 2.19 ± 0.13 l/min; Cr loaded 2.12 ± 0.14 l/min; P < 0.05). The magnitude of the reduction in submaximalV˙o 2 with Cr loading was significantly correlated with the percentage of type II fibers in the vastus lateralis ( r = 0.87; P < 0.01; n = 7), indicating that the effect might be related to changes in motor unit recruitment patterns or the volume of muscle activated.

The purpose of the present study was to examine comprehensively the kinetics of oxygen uptake ( % MathType!MTEF!2!1!+- % feaaeaart1ev0aqatCvAUfKttLearuavP1wzZbqedmvETj2BSbWexL % MBbXgBcf2CPn2qVrwzqf2zLnharyWqVvNCPvMCG4uz3bqee0evGueE % 0jxyaibaieYlf9irVeeu0dXdh9vqqj-hEeeu0xXdbba9frFj0-OqFf % ea0dXdd9vqaq-JfrVkFHe9pgea0dXdar-Jb9hs0dXdbPYxe9vr0-vr % 0-vqpWqaaeaabiGaciaacaqabeaadaqaaqaaaOqaaiqbdAfawzaaca % Gaee4ta80aaSbaaSqaaiabbkdaYaqabaaaaa!386A! $$\dot V{\rm O}_{\rm 2} $$ ) during treadmill running across the moderate, heavy and severe exercise intensity domains. Nine subjects [mean (SD age, 27 (7) years; mass, 69.8 (9.0) kg; maximum % MathType!MTEF!2!1!+- % feaaeaart1ev0aqatCvAUfKttLearuavP1wzZbqedmvETj2BSbWexL % MBbXgBcf2CPn2qVrwzqf2zLnharyWqVvNCPvMCG4uz3bqee0evGueE % 0jxyaibaieYlf9irVeeu0dXdh9vqqj-hEeeu0xXdbba9frFj0-OqFf % ea0dXdd9vqaq-JfrVkFHe9pgea0dXdar-Jb9hs0dXdbPYxe9vr0-vr % 0-vqpWqaaeaabiGaciaacaqabeaadaqaaqaaaOqaaiqbdAfawzaaca % Gaee4ta80aaSbaaSqaaiabbkdaYaqabaaaaa!386A! $$\dot V{\rm O}_{\rm 2} $$ , % MathType!MTEF!2!1!+- % feaaeaart1ev0aqatCvAUfKttLearuavP1wzZbqedmvETj2BSbWexL % MBbXgBcf2CPn2qVrwzqf2zLnharyWqVvNCPvMCG4uz3bqee0evGueE % 0jxyaibaieYlf9irVeeu0dXdh9vqqj-hEeeu0xXdbba9frFj0-OqFf % ea0dXdd9vqaq-JfrVkFHe9pgea0dXdar-Jb9hs0dXdbPYxe9vr0-vr % 0-vqpWqaaeaabiGaciaacaqabeaadaqaaqaaaOqaaiqbdAfawzaaca % Gaee4ta80aaSbaaSqaaiabbkdaYiabb2gaTjabbggaHjabbIha4bqa % baaaaa!3C8B! $$\dot V{\rm O}_{{\rm 2max}} $$ , 4,137 (697) ml·min–1] performed a series of "square-wave" rest-to-exercise transitions of 6 min duration at running speeds equivalent to 80% and 100% of the % MathType!MTEF!2!1!+- % feaaeaart1ev0aqatCvAUfKttLearuavP1wzZbqedmvETj2BSbWexL % MBbXgBcf2CPn2qVrwzqf2zLnharyWqVvNCPvMCG4uz3bqee0evGueE % 0jxyaibaieYlf9irVeeu0dXdh9vqqj-hEeeu0xXdbba9frFj0-OqFf % ea0dXdd9vqaq-JfrVkFHe9pgea0dXdar-Jb9hs0dXdbPYxe9vr0-vr % 0-vqpWqaaeaabiGaciaacaqabeaadaqaaqaaaOqaaiqbdAfawzaaca % Gaee4ta80aaSbaaSqaaiabbkdaYaqabaaaaa!386A! $$\dot V{\rm O}_{\rm 2} $$ at lactate threshold (LT; moderate exercise); and at 20%, 40%, 60%, 80% and 100% of the difference between the % MathType!MTEF!2!1!+- % feaaeaart1ev0aqatCvAUfKttLearuavP1wzZbqedmvETj2BSbWexL % MBbXgBcf2CPn2qVrwzqf2zLnharyWqVvNCPvMCG4uz3bqee0evGueE % 0jxyaibaieYlf9irVeeu0dXdh9vqqj-hEeeu0xXdbba9frFj0-OqFf % ea0dXdd9vqaq-JfrVkFHe9pgea0dXdar-Jb9hs0dXdbPYxe9vr0-vr % 0-vqpWqaaeaabiGaciaacaqabeaadaqaaqaaaOqaaiqbdAfawzaaca % Gaee4ta80aaSbaaSqaaiabbkdaYaqabaaaaa!386A! $$\dot V{\rm O}_{\rm 2} $$ at LT and % MathType!MTEF!2!1!+- % feaaeaart1ev0aqatCvAUfKttLearuavP1wzZbqedmvETj2BSbWexL % MBbXgBcf2CPn2qVrwzqf2zLnharyWqVvNCPvMCG4uz3bqee0evGueE % 0jxyaibaieYlf9irVeeu0dXdh9vqqj-hEeeu0xXdbba9frFj0-OqFf % ea0dXdd9vqaq-JfrVkFHe9pgea0dXdar-Jb9hs0dXdbPYxe9vr0-vr % 0-vqpWqaaeaabiGaciaacaqabeaadaqaaqaaaOqaaiqbdAfawzaaca % Gaee4ta80aaSbaaSqaaiabbkdaYiabb2gaTjabbggaHjabbIha4bqa % baaaaa!3C8B! $$\dot V{\rm O}_{{\rm 2max}} $$ (Δ, heavy and severe exercise). Critical velocity (CV) was also determined using four maximal treadmill runs designed to result in exhaustion in 2–15 min. The % MathType!MTEF!2!1!+- % feaaeaart1ev0aqatCvAUfKttLearuavP1wzZbqedmvETj2BSbWexL % MBbXgBcf2CPn2qVrwzqf2zLnharyWqVvNCPvMCG4uz3bqee0evGueE % 0jxyaibaieYlf9irVeeu0dXdh9vqqj-hEeeu0xXdbba9frFj0-OqFf % ea0dXdd9vqaq-JfrVkFHe9pgea0dXdar-Jb9hs0dXdbPYxe9vr0-vr % 0-vqpWqaaeaabiGaciaacaqabeaadaqaaqaaaOqaaiqbdAfawzaaca % Gaee4ta80aaSbaaSqaaiabbkdaYaqabaaaaa!386A! $$\dot V{\rm O}_{\rm 2} $$ response was modelled using non-linear regression techniques. As expected, the amplitude of the % MathType!MTEF!2!1!+- % feaaeaart1ev0aqatCvAUfKttLearuavP1wzZbqedmvETj2BSbWexL % MBbXgBcf2CPn2qVrwzqf2zLnharyWqVvNCPvMCG4uz3bqee0evGueE % 0jxyaibaieYlf9irVeeu0dXdh9vqqj-hEeeu0xXdbba9frFj0-OqFf % ea0dXdd9vqaq-JfrVkFHe9pgea0dXdar-Jb9hs0dXdbPYxe9vr0-vr % 0-vqpWqaaeaabiGaciaacaqabeaadaqaaqaaaOqaaiqbdAfawzaaca % Gaee4ta80aaSbaaSqaaiabbkdaYaqabaaaaa!386A! $$\dot V{\rm O}_{\rm 2} $$ primary component increased with exercise intensity [from 1,868 (136) ml·min–1 at 80% LT to 3,296 (218) ml·min–1 at 100% Δ, P