Time Trial Test Research Articles

Reliability of Time-to-Exhaustion versus Time-Trial Running Tests in Runners

Both time-to-exhaustion (TTE) and time-trial (TT) exercise tests are commonly used to assess exercise performance, but no study has directly examined the reliability of comparable tests in the same subjects. To evaluate the reliability of comparable TTE and TT treadmill running tests of high and moderately high exercise intensity in endurance-trained male distance runners, and to validate Hinckson and Hopkins TT prediction methods using log-log modeling from TTE results. After familiarization tests, eight endurance-trained male distance runners performed, in a randomized, counterbalanced order, eight trials consisting of two 5-km TT and two 1500-m TT, and four TTE tests run at a speed equivalent to the average speed attained during both the 5-km and 1500-m TT distances. Typical error of the estimate (TEE) expressed as a coefficient of variation for the 5-km TT, 5-km TTE, 1500-m TT, and 1500-m TTE were 2.0, 15.1, 3.3, and 13.2%, respectively. The standard error of the estimate for predicted TT running speed using log-log modeling from TTE results was 0.67%, and the predicted versus criterion reliability of this method revealed TEE values of 1.6% and 2.5% for the prediction of 5-km and 1500-m TT, respectively. The variability of 5-km and 1500-m TT tests was significantly less than for similar TTE treadmill protocols. Despite the greater variability of the TTE tests, log-log modeling using the TTE test results reliably predicted actual TT performance.

Linear decrease in $$\dot V\hbox{O}_{2\max}$$ and performance with increasing altitude in endurance athletes

It has been hypothesized that one reason for decreased .VO(2max) in hypoxia could be the lower maximal exercise intensity achieved in incremental, time or distance trial tests. We hypothesized that (1).VO(2max) would be decreased at altitude even when exercising at the same absolute maximal exercise intensity as at sea level and; (2) the decline in .VO(2max) in endurance-trained athletes (ETA) would be linear across the range from sea level through moderate altitudes. Eight ETA performed combined .VO(2max) and performance tests running to exhaustion at the same speed in a randomized double blind fashion at simulated altitudes of 300, 800, 1,300, 1,800, 2,300 and 2,800 m above sea level using a hypobaric chamber. Douglas bag system was used for respiratory measurements and pulse oximetry was used to estimate arterial O(2) saturation. .VO(2max) declined linearly from 66+/-1.6 ml kg(-1) min(-1) at 300 m to 55+/-1.6 ml kg(-1) min(-1) at 2,800 m corresponding to a 6.3% decrease per 1,000 m increasing altitude (range 4.6-7.5%). Time to exhaustion (performance) at a constant velocity associated with 107% of sea level .VO(2max) decreased with 14.5% (P<0.001) per 1,000 m altitude between 300 and 2,800 m. Both .VO(2max) and performance decreased from 300 to 800 m (P<0.01; P<0.05). Arterial haemoglobin oxygen saturation at test cessation (SpO(2min)) declined from 89.0+/-2.9% at 300 m to 76.5+/-4.0% at 2,800 m (P=0.001). This study report that in ETA during acute exposure to altitude both performance and .VO(2max) decline from 300 to 800 m above sea level and continued to decrease linearly to 2,800 m.

The Relationship Between Laboratory Assessments Of Endurance Capabilities And Time Trial Performance Of Collegiate Cyclists

Field based cycling tests, which utilize computer systems that measure power are recommended by many cycling coaches and professionals as a means to assess a cyclist's preparedness for competition. However, little data are present in the scientific literature that explore(s) the relationships between these field tests and actual physiological markers of performance collected in a controlled laboratory setting. PURPOSE To determine the relationship between a series of laboratory tests designed to assess aerobic capabilities and performance markers during two 4.65 km hill climb time trials and two 10 km flat time trials. METHODS Ten well trained male collegiate cyclists (age: 22.4 ± 4 y; height 179.4 ± 5.7 cm; body mass 74.1 ± 9.4 kg; body fat: 6.3 ± 2.1%; VO2max: 65.5 ± 5.0 ml/kg/min), were recruited in order to determine the relationships between laboratory tests and maximal hill and flat time trial performance. Laboratory assessments of VO2max, and maximal power at VO2max were collected prior to the performance of the first series of time trials. Two pairs of time trials each separate by 15 minutes were performed: two 4.65 km hill climb time trials and two 10 km flat time trials. Time trial performances were assessed with a PowerTap system, which calculated time (s), average velocity (km/h), average power (W), and peak power (W). RESULTS The linear combination of the average velocity of flat trial 1 (ftkmh1) and flat trial 2 (ftkmh2), average power of flat trial 1 (apft1) and flat trail 2 (apft2), and peak power of flat trial 1 (ppft1) and flat trial 2 (ppft2) was significantly related to the VO2max' R2 = 0.95, adjusted R2 = 0.85, F(3,6) = 9.56, p<0.05. Flat time trial prediction equation VO2max (L/min) = −0.111 (ftkmh1) + 0.092 (ftkmh2) + 0.24 (apft1) −0.001 (ppft1) – 0.010 (apft2) + 0.001 (ppft2) + 1.787. The linear combination of the average velocity of hill climb trial 1 (hkmh1) and hill climb trial 2 (hkmh2), average power of hill climb trial 1(aph1) and hill trail 2 (aph2), and peak power of hill climb trial 1 (pph1) and hill climb trial 2 (pph2) was significantly related to the VO2max, R2 = 0.99, adjusted R2 = 0.96, F(3,6) = 34.05, p<0.01. Hill climb time trial prediction equation: VO2max (L/min) = −3.04 (hkmh1) + 0.0117 (hkmh2) +0.35 (aph1) + 0.00(pph1) + 0.15 (aph2) – 0.001 (pph2) + 3.911. CONCLUSION The practice of using of fleld based flat time trial tests and/or hill climb time trial tests appear to be useful in predicting the aerobic capacity of trained collegiate cyclists.

Reproducibility Of A 20 Km Cycling Time-trial In Competitive Cyclists Using The Velotron Pro Cycle Ergometer

Evaluation of performance enhancement in elite athletes is best achieved when using a test that closely simulates actual sport performance. It is also important that the test is as reliable and reproducible as elite athlete performance between competitions (∼ 1% coefficient of variation [CV]). Cycling time trial tests using air-braked cycle ergometers have been shown to be both valid and reproducible in trained cyclists. Reproducibility of time-trial performance using the Velotron Pro electronically-braked cycle ergometer has not yet been reported in such a group. Purpose The purpose of this study was to evaluate performance reproducibility in a laboratory-based 20 km cycling time-trial using the Velotron Pro cycle ergometer in competitive cyclists. Methods Fifteen (13 males, 2 females) highly trained competitive cyclists(maximal aerobic power [VO2max] = 68.4 ± 5.7 ml kg−1min−1) participated in this study. Each subject performed one VO2max test and 3 separate 20 km time trials (TT1, TT2, TT3). Each time trial was separated by a minimum 48 hours with no intense exercise 24 hours prior. Subjects received no feedback as to their performances during the time trial. Data from all time trials were compared using a one-way analysis of variance with alpha set at 0.05. CV and 95% confidence limits (CI) were calculated between individual trials. Results Performance time (Ttot) (30.4 ± 1.9, 30.6 ± 1.9, and 30.7 ± 2.1 min) and average power output (Wavg) (319 ± 47, 314 ± 47, 310 ± 49 watts) were not different across TT1–TT3. Ttot was highly related between TT1 and TT2 (r = 0.99; p<0.01) as well as between TT2 and TT3 (r = 0.99; p<0.01). A low CV was demonstrated between individual trials for Ttot (TT1–TT2 = 0.5% and 95% CI was 0.4% to 0.9%; TT2–TT3 = 0.9% and 95% CI was 0.7% to 1.5%). Conclusions These data show that performance in a 20 km time-trial using the Velotron Pro ergometer is highly reproducible in competitive cyclists. Furthermore, the CV variance demonstrated between trials is comparable to that expected during actual performance in elite athletes. Supported by the World Anti-Doping Agency and Racermate Inc.

EMG Activity does not Change During a Time Trial in Competitive Cyclists

The purpose of the present study was to measure the electromyographic (EMG) activity of four lower limb muscles and the propulsive torque during a cycling time-trial (TT). Nine competitive cyclists (V.O (2max): 73.8 +/- 5.3 ml . min (-1) . kg (-1)) performed two tests separated over a one-week period on a friction-load cycle ergometer equipped with a SRM crankset scientific system: 1) a continuous incremental test for the determination of the peak power output (PPO); and 2) a 30-min TT test at a self-selected work intensity. The EMG activity of the vastus medialis (VM), the rectus femoris (RF), the biceps femoris (BF), and the gastrocnemius medialis (GAS), and the propulsive torque were recorded every 5 min for 10 s. There was no time effect on the power output, the pedalling cadence, and the mean propulsive torque. The EMG activity of the VM and the RF muscles was unchanged during the TT (p > 0.05). The EMG activity of the two knee flexor muscles (BF and GAS) tended to increase with time but it was not significant (p > 0.05). The EMG/torque of the VM and the RF muscles tended to decrease with time but it was not significant (p > 0.05). The lack of increase in the EMG activity of the four investigated muscles seems to indicate that the subjects performed the TT test at a muscular work steady-state.

Effects of Heat Removal Through the Hand on Metabolism and Performance During Cycling Exercise in the Heat

This two-part study tested the hypotheses that the use of a new cooling device, purported to extract heat from the body core through the palm of the hand, would (a) attenuate core temperature rise during submaximal exercise in the heat, thereby suppressing exercise-associated metabolic changes, and (b) facilitate a higher sustained workload, thus shortening the completion time of a time-trial performance test. In Study 1, 8 male triathletes (age 27.9 +/- 2.0 yrs, mass 77.2 +/- 3.1 kg, VO2peak 59.0 +/- 4.1 ml x min(-1) x kg(-1)) cycled for 1 hr at the same absolute workload (approximately 60% VO2peak) in a heated room (31.9 +/- 0.1 degrees C, 24 +/- 1% humidity) on two occasions counterbalanced for cooling (C) or noncooling (NC). In Study 2, 8 similar subjects (age 26.9 +/- 2.0 yrs, mass 75.2 +/- 3.7 kg, VO2peak 54.1 +/- 3.1 ml x min(-1) x kg(-1)) performed two 30-km cycling time-trial performance tests under the same conditions (C(T), NC(T)). In Study 1, cooling attenuated the rise in tympanic temperature (T(TY)) (1.2 +/- 0.2 vs. 1.8 +/- 0.2 degrees C; p < 0.01) and lowered mean oxygen consumption (VO2, 2.4 +/- 0.1 vs. 2.7 +/- 0.1 L x min(-1); p < 0.05) and blood lactate (1.7 +/- 0.2 vs. 2.2 +/- 0.2 mmol x L(-1); p < 0.01) during exercise. There were no significant differences in respiratory exchange ratio (RER), blood glucose, heart rate (HR), face temperature (T(F)), or back temperature (T(B)) between NC and C. In Study 2, time to complete 30 km was 6 +/- 1% less with cooling than without cooling (60.9 +/- 2.0 vs. 64.9 +/- 2.6 min; p < 0.01). During the last 20% of C(T), subjects sustained a workload that was 14 +/- 5% (p = 0.06) higher than NC(T) at the same T(TY) and HR. Heat extraction through the hand during cycle ergometer exercise in the heat can (a) lower T(TY), lactate concentration, and VO2 during a submaximal set-workload test and (b) reduce the time it takes to complete a 30-km time-trial test.

Validity and Stability of a Computerized Metabolic System with Mixing Chamber

The aim of this study was to validate a computerized metabolic system with mixing chamber (Oxycon Pro, Erich Jaeger GmbH, Hoechberg, Germany) against the Douglas bag method (1) over a large range of ventilations and (2) for drift during shorter (25-min time trial) and longer (approximately three months) test periods. Eighteen well-trained/elite cyclists performed graded exercise tests, maximal oxygen uptake tests and time trial tests on an electromagnetic braked cycle ergometer. Respiratory variables were measured simultaneously, once or several times in every test by the Oxycon Pro and the Douglas bag method. (1) Overall, oxygen uptake was 0.8 % (0.03 l x min(-1)) lower with the Oxycon Pro than with the Douglas bag method with a coefficient of variation of 1.2 % (n = 802) (p < 0.05). (2) During the time trials, oxygen uptake measured with the Oxycon Pro gradually decreased from 0.5 % (0.02 l) lower than the Douglas bag method at 5 min to 1.0 % (0.05 l) lower at 25 min (p < 0.05). Over the period of three months of testing, oxygen uptake measured with the Oxycon Pro gradually increased from 1.1 % (0.04 l) lower than the Douglas bag method at the start to 0.5 % (0.02 l) lower at the end (p < 0.05). This study demonstrates that a computerized metabolic system with mixing chamber is an accurate system for measuring oxygen uptake. This applies to testing over a large range of ventilations and for stability both during shorter and longer test periods.

Endurance training of respiratory muscles improves cycling performance in fit young cyclists

BackgroundWhether or not isolated endurance training of the respiratory muscles improves whole-body endurance exercise performance is controversial, with some studies reporting enhancements of 50 % or more, and others reporting no change. Twenty fit (VO2 max 56.0 ml/kg/min), experienced cyclists were randomly assigned to three groups. The experimental group (n = 10) trained their respiratory muscles via 20, 45 min sessions of hyperpnea. The placebo group (n = 4) underwent "sham" training (20, 5 min sessions), and the control group (n = 6) did no training.ResultsAfter training, the experimental group increased their respiratory muscle endurance capacity by 12 %. Performance on a bicycle time trial test designed to last about 40 min improved by 4.7 % (9 of 10 subjects showed improvement). There were no test-re-test improvements in either respiratory muscle or bicycle exercise endurance performance in the placebo group, nor in the control group. After training, the experimental group had significantly higher ventilatory output and VO2, and lower PCO2, during constant work-rate exercise; the placebo and control groups did not show these changes. The perceived respiratory effort was unchanged in spite of the higher ventilation rate after training.ConclusionsThe results suggest that respiratory muscle endurance training improves cycling performance in fit, experienced cyclists. The relative hyperventilation with no change in respiratory effort sensations suggest that respiratory muscle training allows subjects to tolerate the higher exercise ventilatory response without more dyspnea. Whether or not this can explain the enhanced performance is unknown.

Intermittent altitude exposures improve muscular performance at 4,300 m.

Chronic altitude residence improves muscular performance at altitude, but the effect of intermittent altitude exposures (IAE) on muscular performance at altitude has not been defined. The purpose of this study was to determine the effects of 3 wk of IAE, in combination with rest and cycle training, on muscular performance at altitude. Six lowlanders (23 +/- 2 yr, 77 +/- 6 kg; means +/- SE) completed a cycle time trial and adductor pollicis endurance test at sea level and during a 30-h acute exposure to 4,300 m altitude equivalent (barometric pressure = 446 mmHg) once before (pre-IAE) and once after (post-IAE) a 3-wk period of IAE (4 h/day, 5 days/wk, 4,300 m). During each IAE, three subjects cycled for 45-60 min/day at 60%-70% of maximal O2 uptake and three subjects rested. Cycle training during each IAE did not appear to affect muscular performance at altitude. Thus data from all six subjects were combined. Three weeks of IAE resulted in 1) a 21 +/- 6% improvement (P < 0.05) in cycle time-trial performance (min) from pre-IAE (32.8 +/- 3.7) to post-IAE (24.8 +/- 1.2), 2) a 63 +/- 26% improvement (P < 0.05) in adductor pollicis endurance (min) from pre-IAE (9.2 +/- 2.8) to post-IAE (14.8 +/- 4.2), and 3) a 10 +/- 4% increase (P < 0.05) in resting arterial O2 saturation (%) from pre-IAE (82 +/- 2) to post-IAE (90 +/- 1). These improvements in muscular performance after IAE correlated strongly with increases in resting arterial O2 saturation and were comparable to those reported previously after chronic altitude residence. IAE may therefore be used as an alternative to chronic altitude residence to facilitate improvements in muscular performance in athletes, soldiers, mountaineers, shift workers, and others that are deployed to altitude.

Changes in physiological parameters in overtrained Standardbred racehorses.

Various changes in physiological parameters are associated with overtraining, which can be a serious problem for human and equine athletes. A 34 week longitudinal study was conducted to investigate the effects of an acute training overload on physiological parameters in 10 Standardbred racehorses. After 24 weeks of training, horses received 8 weeks of increased workload, followed by 2 weeks recovery. Horses performed a 2400 m time trial and a progressive submaximal exercise test on alternate weeks. By the end of the heavy training period, the average time for the final 1200 m of the time trial increased by 4.0% (95% probable range of true value 1.7-5.8) and peak velocity decreased by 6.9% (4.7-8.9), indicating that overtraining had occurred. Acute overtraining coincided with an increase in blood lactate concentration after the time trial and submaximal test. There were also substantial decreases in bodyweight, plasma cortisol concentration and packed cell volume after the time trial, and in the velocity at a heart rate of 200/min (V200). Parameters that showed no clear-cut change with overtraining included maximal and recovery heart rate, basal plasma cortisol, plasma and red cell volume, and markers of skeletal damage (plasma concentrations of creatine kinase and aspartate aminotransferase). Bodyweight, V200, postexercise blood lactate and plasma cortisol concentrations may all be useful for detecting acute overtraining in equine athletes.

Effects of respiratory muscle training versus placebo on endurance exercise performance

We evaluated the effects of a 5 week (25 sessions); (30–35 min/day, 5 days/week), respiratory muscle training (RMT) program in nine competitive male cyclists. The experimental design included inspiratory resistance strength training (3–5 min/session) and hyperpnea endurance training (30 min/session), a placebo group which used a sham hypoxic trainer ( n=8), and three exercise performance tests, including a highly reproducible 8 km time trial test. RMT intensity, measured once a week in terms of accumulated inspiratory pressure and the level of sustainable hyperpnea increased significantly after 5 weeks (+64% and +19%, respectively). The RMT group showed a significant 8% increase in maximal inspiratory pressure ( P<0.05) while the placebo group showed only a 3.7% increase ( P>0.10). RMT and placebo groups both showed significant increases in the fixed work-rate endurance test performance time (+26% and +16%, respectively) and in the peak work-rate achieved during the incremental maximal oxygen consumption ( V ̇ o 2 max ) test (+9 and +6%). The 8 km time trial performance increased 1.8±1.2% (or 15±10 sec; P<0.01) in the RMT group with 8 of 9 subjects increasing; the placebo group showed a variable non-significant change in 5 of 8 subjects (−0.3±2.7%, P=0.07). The changes observed in these three performance tests were not, however, significantly different between the RMT and placebo groups. Heart rate, ventilation, or venous blood lactate, at equal work-rates during the incremental exercise test or at equal times during the fixed work-rate endurance test were not changed significantly across these exercise trials in either group. We propose that the effect of RMT on exercise performance in highly trained cyclists does not exceed that in a placebo group. Significant placebo and test familiarization effects must be accounted for in experimental designs utilizing performance tests which are critically dependent on volitional effort.

ACUTE INHALATION OF SALBUTAMOL INCREASES ENDURANCE PERFORMANCE IN WELL-TRAINED, NONASTHMATIC ATHLETES

2070 The β2-agonist salbutamol is one of the most widely used drugs to treat asthma. Its bronchodilatatory and systemic effects have also drawn the attention of the athletic community because of their potential ergogenicity. This study examined the effects of a single supratherapeutic dose (800 μg) salbutamol by inhalation on lung function and endurance performance. Sixteen well-trained male cyclists and triathletes (23±3 yr; 73±6 kg; 12.0±2.9 fat%; 11.2±3.4 hours of training per week; 416±40 Wmax) participated in this study. All participants were non-asthmatic, which was confirmed by an exercise provocation test. Exercise performance was measured by means of a time trial on a magnetically braked cycle ergometer (Lode Excalibur) in a double-blind, randomized, placebo controlled cross-over protocol. Each subject performed two time trial tests, which were separated by at least 4 and maximally 13 days. The following lung function parameters were measured using a Microspiro Hi-298 (Chest): peak expiratory flow (PEF), the one-second value of forced expiratory volume (FEV1), forced ventilatory capacity (FVC), and the percentage of FEV1/FVC. After salbutamol treatment the time to complete the time trial was lower than after placebo (3928±231 vs 4010±328 s). A one-tailed paired t-test proved this difference to be significant (p=0.0274). Salbutamol also significantly increased PEF, FEV1 and FEV1/FVC before exercise; PEF remained elevated after the end of the test (one minute post-exercise). This study shows that the expiratory flow of healthy subjects at rest and after completion of an endurance test is increased after the administration of salbutamol. The results of this study also suggest that a single supratherapeutic dose of 800 μg salbutamol increases endurance performance in well-trained, non-asthmatic athletes.

Effects of endurance training on transient oxygen uptake responses in cyclists

The aim of this study was to determine the alterations in oxygen uptake kinetics following endurance training in previously trained athletes. Sixteen competitive cyclists completed 8 weeks of supervised endurance cycle training. Ventilatory threshold, maximal oxygen uptake (V O 2max ), oxygen uptake kinetics and simulated 40-km time-trial tests were performed three times over a 4-week period before training, and then after 4 and 8 weeks of training. The protocol for measuring oxygen uptake kinetics consisted of three square-wave increments from unloaded cycling to a power output of 78 W followed by a single increment from 78 to 156 W. No significant differences in any variables were observed over the pre-training period. The ventilatory threshold and V O 2m ax increased, and the time for 40 km decreased (P < 0.05) with training. Shorter V O 2 time constants and lower heart rates were observed during the protocol for measuring oxygen uptake kinetics (same absolute power output) post-training. These results indicate that oxygen uptake kinetics may be improved with endurance training in previously trained athletes.