Effects of the rotor pedalling system on the performance of trained cyclists during incremental and constant-load cycle-ergometer tests

The aim of this study was to determine the effects of Rotor, a new cycle crank configuration that effectively allows the pedals to move independently throughout the duty cycle, on indices of endurance cycling performance in trained cyclists. Ten cyclists (5 Rotor users and 5 non-users; age (mean +/- SD): 22 +/- 5 y; VO(2)max: 69.5 +/- 5.1 mL. kg(-1).min(-1)) volunteered to participate in the study. On four separate days, the subjects performed four cycle-ergometer tests, i.e. two incremental tests and two 20-min tests. An imposed crank rate of 75 rev.min(-1) was used during all tests. The incremental protocol started at 112.5 W, and the power output was increased by 37.5 W every 3 min until volitional exhaustion. The 20-min tests were performed at a fixed power output equivalent to 80 % of the highest power output that the cyclists maintained for a complete 3-min period during incremental tests. Both types of tests were performed with the conventional crank system and the Rotor following a counter-balanced, cross-over design. Gas exchange parameters were measured in all the tests and blood lactate was determined at the end of each 3-min period (incremental tests) and at the end of the 20-min tests. A three factor (pedalling system used during the tests x habitual pedalling system x power output [incremental tests] or time [20-min tests]) ANOVA with repeated measures on power output (incremental tests) or time (20-min tests) was used to analyse several indices of performance, e.g. peak power output, VO(2)max, lactate threshold, onset of blood lactate accumulation, economy, delta, and gross efficiency. No differences (p > 0.05) were found between the Rotor and conventional systems for any of the aforementioned variables. It seems that the theoretical advantage brought about by the Rotor system, i.e. improved contra-lateral cooperation of both legs, would be minimized in trained cyclists. Although field studies are needed to assess the possible implications, in terms of actual racing, of the new system, commonly used indicators of endurance cycling performance do not seem to be improved with the Rotor in trained cyclists.     

The ventilatory threshold, heart rate, and endurance performance: relationships in elite cyclists

The purpose of this study was to investigate the validity of the ventilatory response during incremental exercise as indication of endurance performance during prolonged high-intensity exercise under field test conditions in elite cyclists. The ventilatory threshold (VT) was assessed in 14 male elite cyclists (age 22.4+/-3.4 years, height 181+/-6 cm, weight 69.2+/-6.8 kg, VO2max 69+/-7 ml x min(-1) x kg(-1)) during an incremental exercise test (20 W x min(-1)). Heart rate and oxygen uptake were assessed at the following ventilatory parameters: 1. Steeper increase of VCO2 as compared to VO2 (V-slope-method); 2. Respiratory exchange ratio (RQ)=0.95 and 1.00; 3. VE/VO2 increase without a concomitant VE/VCO2 (VE/VO2 method). Three weeks following the laboratory tests, the ability to maintain high-intensity exercise was determined during a 40 km time trial on a bicycle. During this time trial the mean heart rate (HR(TT)) and the road racing time (TT) were assessed. The V-slope-method and the VE/VO2 method showed significant correlations with TT (V-slope: r = -0.82; p<0.001; 90% interval of confidence = +/-82 sec; VE/VO2: r=-0.81; p<0.01; 90% interval of confidence = +/-81 sec). Heart rate at the ventilatory parameters and at the maximum heart rate (HRmax) showed significant correlations with HR(TT). The V-slope-method is the preferred method to predict heart rate during prolonged high-intensity exercise (r=0.93; p<0.0001; 90% interval of confidence: +/-4.8 beats x min(-1)). For predicting heart rate during prolonged high-intensity exercise using an incremental exercise test (20 W x min(-1)), without the knowledge of ventilatory parameters, we recommend using the regression formula: H(TT)=0.84 x Hmax + 14.3 beats x min(-1) (r=0.85; p<0.001).     

Critical power is related to cycling time trial performance.

The purpose of this study was to evaluate critical power (W(CP)) as an indicator of aerobic fitness in trained cyclists, and to determine its relationship to cycling time trial (TT) performance. Thirteen competitive USCF category 2 or 3 cyclists provided season's best 40 km TT times (mean [SD]) time = 59.6 min (3.1), and performed two 17 km TT under controlled conditions (26.6 min [1.1]). Ventilatory threshold (VT) and VO2max were determined from a maximal incremental test. W(CP) was calculated using the results of four all-out constant power tests. Mean W(CP) was 299 (61) W or 4.1 W x kg(-1), VT was 3616 (750) ml x min(-1) or 49.8 ml x kg(-1) x min(-1) (7.5), and VO2max was 4596 ml x min(-1) or 63.5 ml x kg(-1) x min(-1) (8.0). W(CP) was strongly related to VT and VO2max, demonstrating that it can serve as a measure of aerobic fitness in this population. Expressions of W(CP) were slightly to considerably more highly related to 17 km and 40 km TT performances (r = -0.77 to -0.91) than were expressions of VT and VO2max (r = -0.71 to -0.87). It is concluded that W(CP) provides an aerobic fitness measure for competitive cyclists which can be obtained without invasive testing. In addition, W(CP) is strongly related to the TT performance of competitive cyclists.     

Physiological variables at lactate threshold under-represent cycling time-trial intensity

BACKGROUND: The importance of lactate threshold (LT) as a determinant of performance in endurance sports has been established. In addition, it has been shown that during running and selected other endurance competitions, athletes perform at a velocity and VO2 slightly above LT for the duration of the event. Prior work indicates however, that this may not be true during a cycling time-trial (TT). This investigation sought to compare physiological variables during a 20-k TT with those corresponding to the athlete's LT. METHODS: Thirteen male cyclists (22.7+/-0.8 yrs; 180.6+/-8.0 cm; 77.1+/-10.0 kg; 8.3+/-2.5% fat; 4.9+/-2.2 l x min(-1), VO2max) participated in the study. Subjects performed a graded protocol starting at 150 Watts (W) to determine LT (2 mmol x L(-1) above baseline) which consisted of 20 W increases every 4-min. Following an 8 min-recovery, subjects cycled at the wattage corresponding to LT-20 W for 1 min and then workload increased 20 W every minute until volitional exhaustion to determine VO2max x On a separate occasion a self-paced, 20-k TT was completed. RESULTS: Mean values of blood lactate, HR and % HRmax, VO2 and % VO2max, and power output throughout the 20-k TT were greater (p<0.01) than those at LT. During the TT these cyclists performed at an intensity well above LT (blood lactate=252.0+/-0.1%, HR=9.4+/-0.03%, %HRmax=9.2+/-0.15%, VO2=26.5+/-0.7%, %VO2max=17.2+/-0.08% and power out-put=14.8+/-0.14% above LT) for over 30 min. CONCLUSIONS: Therefore, while LT may be highly correlated to performance, it may not be representative of race pace for a cycling TT, and may be questionable as a benchmark used to prescribe training intensity for competitive TT-cycling.     

Level ground and uphill cycling ability in professional road cycling.

PURPOSE: To evaluate the physiological capacities and performance of professional road cyclists in relation to their morphotype-dependent speciality. METHODS: 24 world-class cyclists, classified as flat terrain (FT, N = 5), time trial (TT, N = 4), all terrain (AT, N = 6). and uphill (UH, N = 9) specialists, completed an incremental laboratory cycling test to assess maximal power output (Wmax), maximal oxygen uptake (VO2max), lactate threshold (LT), and onset of blood lactate accumulation (OBLA). RESULTS: UH had a higher frontal area (FA):body mass (BM) ratio (5.23 +/- 0.09 m2 x kg(-1) x 10(-3)) than FT and TT (P < 0.05). FT showed the highest absolute Wmax (481 +/- 18 W), and UH the highest Wmax relative to BM (6.47 +/- 0.33 W x kg(-1)). WLT and W(OBLA) values were significantly higher in FT (356 +/- 41 and 417 +/- 45 W) and TT (357 +/- 41 and 409 +/- 46 W) than in UH (308 +/- 46 and 356 +/- 41). Scaling of these values relative to FA and BM exponents 0.32 and 0.79 minimized group differences, but considerable differences among mean group values remained. FT and TT had the highest Wmax per FA unit (1300 +/- 62 and 1293 +/- 57 W x m2), whereas TT had the highest absolute W x kg(-0.32) and W x kg(-0.79), as well as W x kg(-0.32), W x kg(-0.79), and W x m2 at the LT and OBLA. CONCLUSIONS: i) Scaling of maximal and submaximal physiological values showed a performance advantage of TT over FT, AT, and UH in all cycling terrains and conditions; and ii) mass exponents of 0.32 and 1 were the most appropriate to evaluate level and uphill cycling ability, respectively, whereas absolute Wmax values are recommended for performance-prediction in short events on level terrain, and W(LT) and W(OBLA) in longer time trials and uphill cycling.     

Inverse relationship between VO2max and economy/efficiency in world-class cyclists

PURPOSE: To determine the relationship that exists between VO2max and cycling economy/efficiency during intense, submaximal exercise in world-class road professional cyclists. METHODS Each of 11 male cyclists (26+/-1 yr (mean +/- SEM); VO2max: 72.0 +/- 1.8 mL x kg(-1) x min(-1)) performed: 1) a ramp test for O2max determination and 2) a constant-load test of 20-min duration at the power output eliciting 80% of subjects' VO2max during the previous ramp test (mean power output of 385 +/- 7 W). Cycling economy (CE) and gross mechanical efficiency (GE) were calculated during the constant-load tests. RESULTS: CE and GE averaged 85.2 +/- 2.3 W x L(-1) x min(-1) and 24.5 +/- 0.7%, respectively. An inverse, significant correlation was found between 1) VO2max (mL x kg(-0.32) x min(-1)) and both CE (r = -0.71; P = 0.01) and GE (-0.72; P = 0.01), and 2) VO2max (mL x kg(-1) x min(-1)) and both CE (r = -0.65; P = 0.03) and GE (-0.64; P = 0.03). CONCLUSIONS: A high CE/GE seems to compensate for a relatively low VO2max in professional cyclists.     

Comparison of Wpeak, VO2peak and the ventilation threshold from two different incremental exercise tests: Relationship to endurance performance

This report presents data comparing the peak rate of oxygen consumption (VO2(peak)), peak power output (W(peak)) and the ventilation threshold (VT) obtained from two different incremental cycle exercise tests performed by nine well trained triathletes (Mean +/- SD age 32 +/- 3 yrs; body mass 77.4 +/- 4.9 kg and height 185 +/- 3 cm). Furthermore, the relationship between these variables and the average sustained power output (W) during a 90 min cycle time trial (TT) was also determined. The two incremental exercise tests involved a 'short' test, which commenced at 150 W with 30 W increments every 60 s until exhaustion. The second ('long') incremental test commenced at a power output representing 50% of the W(peak) obtained in the short test. The subjects were then required to increase the power output by 5% every 3 min until exhaustion. The results showed the W(peak) (W) in the short test was significantly (p < 0.01) higher than in the long test. However, there was no significant difference in the VO2(peak) (1 x min(-1)) between the two tests. There was a weak but significant correlation between W(peak) (W) and VO2(peak) (l x min(-1)) (r = 0.72: p < 0.05) in the short (60 s stage) test but not the long (3 min stage) test (r = 0.52). There were no significant differences and good agreement between for the heart rate (HR) (b x min(-1)) and oxygen consumption (VO2) corresponding to the VT. In contrast, the power output (W) corresponding to the VT was significantly different and not comparable between the long and short incremental tests. The cycle TT performance was most correlated to the W(peak) (W) (r = 0.94; p < 0.01) and the VT (W) (r = 0.75; p < 0.05) from the long test as well as the VO2(peak) (l x min(-1)) obtained from the short incremental test (r = 0.75; p < 0.01). These data suggest that the length of stages during incremental cycle exercise may influence the W(peak) and in turn the relationship of this variable to VO2(peak). Furthermore, the W(peak) obtained from a test incorporating 3 min stage increments represents the best indicator of 90 min cycle performance in well-trained triathletes.     

Are peak oxygen uptake and power output at maximal lactate steady state obtained from a 3-min all-out cycle test?

The aim of the study was to examine whether 1) the power output attained in the last 30?s of a 3-min all-out test (P (end)) correlates with the power output at maximal lactate steady state (P (MLSS)) and whether 2) peak oxygen uptake (VO (2peak)) can be obtained from a 3-min all-out test in well-trained cyclists. 18 cyclists (23±3?years; 186.1±6.9?cm; 79.1±8.2?kg; VO (2peak): 63.2±5.2?mL · kg (-1) · min (-1)) performed a ramp test, a 3-min all-out test and several submaximal constant 30?min-workload tests at +15, 0, -15, -30, -45, -60,-75, -90?W of P (end) to obtain P (MLSS). P (MLSS) was significantly lower compared to P (END) ( P<0.001; mean difference: 54±18?W) with a high correlation (r=0.93; R (2)=0.87; P<0.001) but great intra-individual variability (15-90?W). There were no mean differences between the ramp-VO (2peak) and 3-min all-out cycling VO (2peak) ( P=0.29; mean difference: 133±514?mL · min (-1)) showing significant correlation (r=0.60; R (2)=0.37; P=0.006) but great intra-individual variability (1?057-1?312?mL · min (-1)). We therefore suggest that in well-trained cyclists a 3-min all-out test is 1) not sufficient to obtain P (MLSS) and 2) should not be applied to assess VO (2peak).     

Prediction of maximal effort bicycle ergometer endurance performance

Fifteen competitive cyclists and 15 subjects not involved in competitive cycling were studied to determine the relationship between VO2max, lactate threshold (LT), fixed blood lactate concentrations, body composition parameters, and maximal effort bicycle ergometer performance. The subjects were assessed for VO2max, LT, VOLT, and VO2 associated with blood lactate concentrations of 3, 4, 5, and 6 mM/l (VO2 3 mM-VO2 6 mM/l), using an incremental protocol on the bicycle ergometer. Body composition was determined by underwater weighing. Subjects also completed two 10-min drop-off performance tests (starting at 70 rpm) at the same absolute power output (4.5 kg resistance, 1890 kgm/min) (ABS) and at the same relative power output (the highest power output completed for 3 min on the VO2max test) (REL). Metabolic measures and revolution scores were collected on a minute-by-minute basis during the performance tests. The results indicated that the competitive cyclists had higher VO2max (4.25 +/- 0.39 vs 3.50 +/- 0.54 l/min); VO2 LT (2.91 +/- 0.55 vs 1.66 +/- 0.49 l/min); VO2 3 mM, VO2 4 mM, VO2 5 mM, VO2 6 mM, VO2 LT/VO2max (68.5 +/- 11.2 vs 47.2 +/- 10.9 %); max resistance (5.70 +/- 0.56 vs 4.63 +/- 0.67 kg); and resistance at LT (3.57 +/- 0.70 vs 1.93 +/- 0.68 kg) as compared to the noncompetitive subjects (P less than 0.05). Correlational analysis revealed poor prediction between metabolic measures and the homogeneous cumulative rpm scores during the REL test.2+ subjects (r = 0.60 to 0.90).(ABSTRACT TRUNCATED AT 250 WORDS)     

Frequency of the VO2max plateau phenomenon in world-class cyclists

We aimed to determine the frequency of the VO2max plateau phenomenon in top-level male professional road cyclists (n = 38; VO2max [mean +/- SD]: 73.5 +/- 5.5 ml.kg(-1).min(-1)) and in healthy, sedentary male controls (n = 37; VO2max: 42.7 +/- 5.6 ml.kg(-1).min(-1)). All subjects performed a continuous incremental cycle-ergometer test of 1-min workloads until exhaustion. Power output was increased from a starting value of 25 W (cyclists) or 20 W (controls) at the rate of 25 W.min(-1) (cyclists) or 20 W.min(-1) (controls) until volitional exhaustion. We measured gas-exchange and heart rate (HR) throughout the test. Blood concentrations of lactate (BLa) were measured at end-exercise in both groups. We defined maximal exercise exertion as the attainment of a respiratory exchange rate (RER) >or= 1.1; HR > 95 % age-predicted maximum; and BLa > 8 mmo.l(-1). The VO2max plateau phenomenon was defined as an increase in two or more consecutive 1-min mean VO2 values of less than 1.5 ml.kg(-1).min(-1). Most cyclists met our criteria for maximal exercise effort (RER > 1.1, 100 %; 95 % predicted maximal HR [HRmax], 82 %; BLa > 8 mmol.l(-1), 84 %). However, the proportion of cyclists attaining a V.O (2max) plateau was considerably lower, i.e., 47 %. The majority of controls met the criteria for maximal exercise effort (RER > 1.1, 100 %; predicted HRmax, 68 %; BLa > 8 mmol. l(-1), 73 %), but the proportion of these subjects with a VO2max plateau was only 24 % (significantly lower proportion than in cyclists [p < 0.05]). Scientists should consider 1) if typical criteria of attainment of maximal effort are sufficiently stringent, especially in elite endurance athletes; and 2) whether those humans exhibiting the VO2max plateau phenomenon are those who perform an absolute maximum effort or there are additional distinctive features associated with this phenomenon.     

Correlations between lactate and ventilatory thresholds and the maximal lactate steady state in elite cyclists

We investigated the validity of different lactate and ventilatory threshold methods, to estimate heart rate and power output corresponding with the maximal lactate steady-state (MLSS) in elite cyclists. Elite cyclists (n = 21; 21 +/- 0.4 y; VO2peak, 5.4 +/- 0.2 l x min (-1)) performed either one (n = 10) or two (n = 11) maximal graded exercise tests, as well as two to three 30-min constant-load tests to determine MLSS, on their personal race bicycle which was mounted on an ergometer. Initial workload for the graded tests was 100 Watt and was increased by either 5 % of body mass (in Watt) with every 30 s (T30 s), or 60 % of body mass (in Watt) with every 6 min (T6min). MLSS was defined as the highest constant workload during which lactate increased no more than 1 mmol x l (-1) from min 10 to 30. In T30 s and T6 min the 4 mmol (TH-La4), the Conconi (TH-Con) and dmax (TH-Dm) lactate threshold were determined. The dmax lactate threshold was defined as the point that yields the maximal distance from the lactate curve to the line formed by the lowest and highest lactate values of the curve. In T30 s also ventilatory (TH-Ve) and Vslope (TH-Vs) thresholds were calculated. Time to exhaustion was 36 +/- 1 min for T30 s versus 39 +/- 1 min for T6 min. None of the threshold measures in T30 s, except TH-Vs (r2 = 0.77 for heart rate) correlated with either MLSS heart rate or power output. During T6 min, power output at TH-Dm was closely correlated with MLSS power (r2=0.72). Low correlations were found between MLSS heart rate and heart rate measured at TH-Dm (r2=0.46) and TH-La4 (r2=0.25), respectively, during T6 min. It is concluded that it is not possible to precisely predict heart rate or power output corresponding with MLSS in elite cyclists, from a single graded exercise test causing exhaustion within 35-40 min. The validity of MLSS predicted from an incremental test must be verified by a 30-min constant-load test.     

Analysis of the aerobic-anaerobic transition in elite cyclists during incremental exercise with the use of electromyography

OBJECTIVES: To investigate the validity and reliability of surface electromyography (EMG) as a new non-invasive determinant of the metabolic response to incremental exercise in elite cyclists. The relation between EMG activity and other more conventional methods for analysing the aerobic-anaerobic transition such as blood lactate measurements (lactate threshold (LT) and onset of blood lactate accumulation (OBLA)) and ventilatory parameters (ventilatory thresholds 1 and 2 (VT1 and VT2)) was studied. METHODS: Twenty eight elite road cyclists (age 24 (4) years; VO2MAX 69.9 (6.4) ml/kg/min; values mean (SD)) were selected as subjects. Each of them performed a ramp protocol (starting at 0 W, with increases of 5 W every 12 seconds) on a cycle ergometer (validity study). In addition, 15 of them performed the same test twice (reliability study). During the tests, data on gas exchange and blood lactate levels were collected to determine VT1, VT2, LT, and OBLA. The root mean squares of EMG signals (rms-EMG) were recorded from both the vastus lateralis and the rectus femoris at each intensity using surface electrodes. RESULTS: A two threshold response was detected in the rms-EMG recordings from both muscles in 90% of subjects, with two breakpoints, EMGT1 and EMGT2, at around 60-70% and 80-90% of VO2MAX respectively. The results of the reliability study showed no significant differences (p > 0.05) between mean values of EMGT1 and EMGT2 obtained in both tests. Furthermore, no significant differences (p > 0.05) existed between mean values of EMGT1, in the vastus lateralis and rectus femoris, and VT1 and LT (62.8 (14.5) and 69.0 (6.2) and 64.6 (6.4) and 68.7 (8.2)% of VO2MAX respectively), or between mean values of EMGT2, in the vastus lateralis and rectus femoris, and VT2 and OBLA (86.9 (9.0) and 88.0 (6.2) and 84.6 (6.5) and 87.7 (6.4)% of VO2MAX respectively). CONCLUSION: rms-EMG may be a useful complementary non-invasive method for analysing the aerobic-anaerobic transition (ventilatory and lactate thresholds) in elite cyclists.     

Ventilatory and plasma lactate response with different exercise protocols: a comparison of methods

The purpose of this study was to compare the methods used to identify abrupt changes in ventilation or plasma lactate (LA) during exercise. Ten males randomly performed a 1-, 3-, and 5-min, 30-W incremental cycle ergometer test to fatigue. The first change in VE and VCO2 relative to VO2 (ventilation threshold, VT1) was determined from plots of VE, VE X VO2-1, and excess CO2 vs VO2. Data were also analyzed for a second change in VE (VT2) relative to both VCO2 and VO2 using plots of VE and VE X VCO2(-1) vs VO2 and semi-log plots of VE X VO2(-1) and VE X VCO2(-1) vs VO2. Arterialized blood samples were taken each 1.0, 1.5, or 2.5 min for the 1-, 3-, and 5-min tests, respectively, to determine the LA threshold (LT) and the onset of blood lactate accumulation (4 mM, OBLA) and 1, 2, 5, 7.5, and 10 min after all tests to calculate the individual anaerobic threshold (IAT). At weekly intervals, subjects also exercised for 10 min at eight different power outputs (W) to define the onset of plasma lactate accumulation (OPLA). Results showed that VO2max was significantly higher for the 1-min (3.88 l X min-1)vs the 3- or 5-min tests (3.65 l X min-1). With increasing W duration, VT1 from either VE or VE X VO2-1 vs VO2 were similar (1.77 vs 1.72 l X min-1) but significantly lower using excess CO2 (1.23 l X min-1) . VO2 at LT (1.62 l X min-1) and OPLA (1.73 l X min-1) were similar to VT1.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effects of short-term endurance training on muscle deoxygenation trends using NIRS

PURPOSE: This study examined changes in cardiorespiratory responses and muscle deoxygenation trends to test the hypothesis that both central and peripheral adaptations would contribute to the improvements in VO(2max) and simulated cycling performance after short-term high-intensity training. METHODS: Eight male cyclists performed an incremental cycle ergometer test to voluntary exhaustion, and a simulated 20-km time trial (20TT) on wind-loaded rollers before and after training (60 min x 5 d x wk(-1) x 3 wk at 85-90% VO(2max). Near-infrared spectroscopy (NIRS) was used to evaluate the trend in vastus medialis hemoglobin/myoglobin deoxygenation (Hb/Mb-O(2) during both tests pre- and post-training. RESULTS: Training induced significant increases (P 0.05) in the VO(2) (4.02 +/- 0.52 to 4.04 +/- 0.51), heart rate (176 +/- 9 to 173 +/- 8 beats x min ) or O pulse (22.4 +/- 3.2 to 23.5 +/- 2.8 mL O(2) x beat(-1)). However, mean muscle deoxygenation during the 20TT was significantly lower after training (-550 +/- 292 to -707 +/- 227 mV, P 相似文献   

Exercise intensity during competition time trials in professional road cycling

PURPOSE: To estimate, upon competition heart rate (HR), exercise intensity during time trials (TT) in professional road cycling. METHODS: Eighteen world-class cyclists completed an incremental laboratory cycling test to assess maximal power output (Wmax), maximal HR (HRmax), onset of blood lactate accumulation (OBLA), lactate threshold (LT), and a HR-power output relationship. An OBLA(ZONE) (HR(OBLA) +/- 3 beats x min(-1)) and a LT(ZONE) (HR(LT) +/- 3 beats x min(-1)) were described. HR was monitored during 12 prologue (<10 km, PTT), 18 short (<40 km, STT), 19 long (>40 km, LTT), eight uphill (UTT), and seven team (TTT) time trials. A HR-power output relationship was computed to estimate each cyclist's power output during TT racing from competition HR. Competition training impulse (TRIMP) values were estimated from HR and race duration. RESULTS: %HRmax were 89+/-3%, 85+/-5%, 80+/-5%, 78+/-3%, and 82+/-2% in PTT, STT, LTT, UTT, and TTT, respectively. The amount of TRIMP were, respectively, 21+/-3, 77+/-23, 122+/-27, 129+/-14, and 146+/-6. Competition HR values relative to HR(OBLA) and HR(LT) were, respectively, 100+/-3%, 114+/-8% in PTT, 95+/-7%, 108+/-9% in STT, 89+/-5%, 103+/-8% in LTT, 87+/-2%, 101+/-5% in UTT, and 91+/-4%, 105+/-11% in TTT. CONCLUSIONS: %HRmax, TRIMP and time distribution around HR(OBLA) and HR(LT) reflected the physiological demands of different TT categories. HR(OBLA) and HR(LT) were accurate intensity markers in events lasting, respectively, < or =30 (PTT and STT) and > or =30 min (LTT, UTT, TTT).     

Muscle glycogen utilization and the expression of relative exercise intensity

Previous research has shown that the rate of muscle glycogen utilization is related to exercise intensity expressed relative to maximal aerobic power (%VO2max). The purpose of this study was to compare the relationship between glycogen utilization and %VO2max to that between glycogen utilization and intensity expressed relative to the onset of blood lactate accumulation (%OBLA) during cycle exercise. It was hypothesized that the rate of glycogen utilization would be related more closely to intensity expressed as %OBLA than to intensity expressed as %VO2max. Nineteen subjects (15 males and 4 females) performed two separate tests to determine VO2max and OBLA during continuous incremental exercise. On a third occasion biopsies were taken from the m. vastus lateralis before and after 30 min of exercise at randomly assigned intensities ranging from 50-80% VO2max, corresponding to 67-117% OBLA. There was a large inter-subject variation in aerobic fitness with VO2max ranging from 34 to 66 mL.kg-1.min-1 and OBLA ranging from 64-84% VO2max. Absolute VO2max and the VO2 at OBLA were correlated strongly (r = 0.90). The change in glycogen concentration during the 30-min exercise bout ranged from an increase of 58 to a depletion of 200 mmol glucose units.kg-1 dry muscle weight. Neither absolute nor relative glycogen utilization was significantly related to the exercise intensity expressed as either %VO2max or %OBLA. Stepwise multiple regression was used to identify variables which could account for the variation in glycogen depletion.(ABSTRACT TRUNCATED AT 250 WORDS)     

Kinetics of VO(2) in professional cyclists

PURPOSE: To analyze the kinetics of oxygen uptake (VO(2)) in professional road cyclists during a ramp cycle ergometer test and to compare the results with those derived from well-trained amateur cyclists. METHODS: Twelve professional cyclists (P group; 25 +/- 1 yr; maximal power output (W(max)), 508.3 +/- 9.3 watts) and 10 amateur cyclists (A group; 22 +/- 1 y; W(max), 429.9 +/- 8.6 watts) performed a ramp test until exhaustion (power output increases of 25 watts x min(-1)). The regression lines of the VO(2):power output (W) relationship were calculated for the following three phases: phase I (below the lactate threshold (LT)), phase II (between LT and the respiratory compensation point (RCP)), and phase III (above RCP). RESULTS: In group P, the mean slope (Delta VO(2):Delta W) of the VO(2):W relationship decreased significantly (P < 0.01) across the three phases (9.9 +/- 0.1, 8.9 +/- 0.2, and 3.8 +/- 0.6 mL O(2) x watts(-1) x min(-1) for phases I, II, and III, respectively). No significant differences (P > 0.05) were found between phases I and II (P > 0.05) in group A, whereas Delta VO(2):Delta W significantly increased in phase III (P < 0.01), compared with phase II (10.2 +/- 0.3, 9.2 +/- 0.4, and 10.1 +/- 1.1 mL O(2) x watts(-1) x min(-1) in phases I, II, and III, respectively). The mean value of Delta VO(2):Delta W for phase III was significantly lower in group P than in group A (P < 0.01). CONCLUSION: Contrary to the case in amateur riders, the rise in VO(2) in professional cyclists is attenuated at moderate to high workloads. This is possibly an adaptation to the higher demands of their training/competition schedule.     

A 3-min all-out test to determine peak oxygen uptake and the maximal steady state

PURPOSE: We tested the hypothesis that a 3-min all-out cycling test would provide a measure of peak oxygen uptake (VO2peak) and estimate the maximal steady-state power output. METHODS: Eleven habitually active subjects performed a ramp test, three 3-min all-out tests against a fixed resistance, and two further submaximal tests lasting up to 30 min, 15 W below or above the power output attained in the last 30 s of the 3-min test (the end-test power). RESULTS: The VO2peak measured during the 3-min all-out test (mean +/- SD: 3.78 +/- 0.68 L x min(-1)) was not different from that of the ramp test (3.84 +/- 0.79 L x min(-1); P = 0.75). The end-test power (257 +/- 49 W) was significantly lower than that at the end of the ramp test (368 +/- 73 W) and significantly higher than the power at the gas exchange threshold (169 +/- 55 W; P < 0.001). Nine subjects were able to complete 30 min of exercise at 15 W below the end-test power, and seven of these did so with a steady-state blood [lactate] and VO2 response profile. In contrast, when subjects exercised at 15 W above the end-test power, blood [lactate] and VO2 rose inexorably until exhaustion, which occurred in approximately 13 +/- 7 min. CONCLUSIONS: These data suggest that a 3-min all-out exercise test can be used to establish VO2peak and to estimate the maximal steady state.     

Incremental test protocol, recovery mode and the individual anaerobic threshold

The individual anaerobic threshold (IAT) is defined as the highest metabolic rate at which blood lactate (LA) concentrations are maintained at a steady-state during prolonged exercise. The purpose of this study was to compare the effects of active and passive recovery on the determination of IAT following both a submaximal or maximal incremental exercise test. Seven males (VO2max = 57.6 +/- 5.8 ml.kg-1.min -1) did two submaximal, incremental cycle exercise tests (30 W and 4 min per step) and two maximal incremental tests. Blood was sampled repeatedly during exercise and for 12 min during the subsequent recovery period, which was passive for one submaximal and one maximal test and active (approximately 35% VO2max) during the other tests. An IAT metabolic rate and power output were calculated for the submax-passive (IATsp, LA = 1.85 +/- 0.42 mmol.l-1), max-passive (IATmp, LA = 3.41 +/- 1.14 mmol.l-1), submax-active (IATsa, LA = 2.13 +/- 0.45 mmol.l-1) and max-active (IATma, LA = 3.44 +/- 0.73 mmol.l-1) protocols. At weekly intervals, the subjects exercised for 30 min at one of the four IAT metabolic rates. Active recovery did not affect the calculation of IAT, but following the maximal incremental tests, IAT occurred at a higher (p less than 0.05) power output, absolute VO2 and %VO2max (71% VO2max) compared with the IAT determined with the submaximal incremental tests (61% VO2max).(ABSTRACT TRUNCATED AT 250 WORDS)     

Effect of warm-up on cycle time trial performance

PURPOSE: This study was designed to determine the effect of warm-up on 3-km cycling time trial (TT) performance, and the influence of accelerated VO(2) kinetics on such effect. METHODS: Eight well-trained road cyclists, habituated to 3-km time trials, performed randomly ordered 3-km TT after a) no warm-up (NWU), b) easy warm-up (EWU) (15 min comprised of 5-min segments at 70, 80, and 90% of ventilatory threshold (VT) followed by 2 min of rest), or c) hard warm-up (HWU) (15 min comprised of 5-min segments at 70, 80, and 90% VT, plus 3 min at the respiratory compensation threshold (RCT) followed by 6 min of rest). VO(2) and power output (SRM), aerobic and anaerobic energy contributions, and VO(2) kinetics (mean response time to 63% of the VO(2) observed at 2 km) were determined throughout each TT. RESULTS: Three-kilometer TT performance was (P < 0.05) improved for both EWU (266.8 +/- 12.0 s) (-2.8%) and HWU (267.3 +/- 10.4 s) (-2.6%) versus NWU (274.4 +/- 12.1 s). The gain in performance was predominantly during the first 1000 m in both EWU (48% of gain) and HWU (53% of gain). This reflected a higher power output during the first 1000 m in both EWU (384 W) and HWU warm-up (386 W) versus NWU (344 W) trials. The mean response time was faster in both EWU (45 +/- 10 s) and HWU (41 +/- 12 s) versus NWU (52 +/- 13 s) trials. There were no differences in anaerobic power output during the trials, but aerobic power output during the first 1000 m was larger during both EWU (203 W) and HWU (208 W) versus NWU (163 W) trials. CONCLUSIONS: During endurance events of intermediate duration (4-5 min), performance is enhanced by warm-up irrespective of warm-up intensity. The improved performance is related to an acceleration of VO(2) kinetics.