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1.
The aims of this study were to determine if the primary time constant (tau) for oxygen uptake (VO2) at the onset of moderate-intensity treadmill exercise is related to endurance running performance, and to establish if tau could be considered a determinant of endurance running performance. Thirty-six endurance trained male runners performed a series of laboratory tests, on separate days, to determine maximal oxygen uptake (VO2max), the ventilatory threshold (VT) and running economy. In addition, runners completed six transitions from walking (4 km x h-1) to moderate-intensity running (80% VT) for the determination of the VO2 primary time constant and mean response time. During all tests, pulmonary gas-exchange was measured breath-by-breath. Endurance running performance was determined using a treadmill 5-km time-trial, after which runners were considered as combined performers (n=36) and, using a ranking system, high performers (n=10) and low performers (n=10). Relationships between tau and endurance running performance were quantified using correlation coefficients (r). Stepwise multiple regression was used to determine the primary predictor variables of endurance running performance in combined performers. Moderate correlations were observed between tau, mean response time and endurance running performance, but only for the combined performers (r=-0.55, P=0.001 and r=-0.50, P=0.002, respectively). The regression model for predicting 5-km performance did not include tau or mean response time. The velocity at VO2max was strongly correlated to endurance running performance in all groups (r=0.72 - 0.84, P < 0.01) and contributed substantially to the prediction of performance. In conclusion, the results suggest that despite their role in determining the oxygen deficit and having a moderate relationship with endurance running performance, neither tau nor mean response time is a primary determinant of endurance running performance.  相似文献   

2.
The purpose of the present study was to assess fitness and running performance in a group of recreational runners (men, n = 18; women, n = 13). 'Fitness' was determined on the basis of their physiological and metabolic responses during maximal and submaximal exercise. There were strong correlations between VO2 max and treadmill running speeds equivalent to blood lactate concentrations of 2 mmol l-1 (V-2 mM) or 4 mmol l-1 (V-4 mM), 'relative running economy' and 5 km times (r = -0.84), but modest and non-significant correlations between muscle fibre composition and running performance. The results of the submaximal exercise tests suggested that the female runners were as well trained as the male runners. However, the men still recorded faster 5 km times (19.20 +/- 1.97 min vs 20.97 +/- 1.70 min; P less than 0.05). Therefore the of the present study suggest that the faster performance times recorded by the men were best explained by their higher VO2 max values, rather than their training status per se.  相似文献   

3.
Comparison of maximal anaerobic running tests on a treadmill and track   总被引：1，自引：0，他引：1  
To develop a track version of the maximal anaerobic running test, 10 sprint runners and 12 distance runners performed the test on a treadmill and on a track. The treadmill test consisted of incremental 20-s runs with a 100-s recovery between the runs. On the track, 20-s runs were replaced by 150-m runs. To determine the blood lactate versus running velocity curve, fingertip blood samples were taken for analysis of blood lactate concentration at rest and after each run. For both the treadmill and track protocols, maximal running velocity (v max), the velocities associated with blood lactate concentrations of 10 mmol x l-1 (v10 mM) and 5 mmol x l(-1) (v5 mM), and the peak blood lactate concentration were determined. The results of both protocols were compared with the seasonal best 400-m runs for the sprint runners and seasonal best 1000-m time-trials for the distance runners. Maximal running velocity was significantly higher on the track (7.57 +/- 0.79 m x s(-1)) than on the treadmill (7.13 +/- 0.75 m x s(-1)), and sprint runners had significantly higher vmax, v10 mM, and peak blood lactate concentration than distance runners (P < 0.05). The Pearson product--moment correlation coefficients between the variables for the track and treadmill protocols were 0.96 (v max), 0.82 (v10 mM), 0.70 (v5 mM), and 0.78 (peak blood lactate concentration) (P < 0.05). In sprint runners, the velocity of the seasonal best 400-m run correlated positively with vmax in the treadmill (r = 0.90, P < 0.001) and track protocols (r = 0.92, P < 0.001). In distance runners, a positive correlation was observed between the velocity of the 1000-m time-trial and vmax in the treadmill (r = 0.70, P < 0.01) and track protocols (r = 0.63, P < 0.05). It is apparent that the results from the track protocol are related to, and in agreement with, the results of the treadmill protocol. In conclusion, the track version of the maximal anaerobic running test is a valid means of measuring different determinants of sprint running performance.  相似文献   

4.
Endurance running performance in athletes with asthma   总被引：1，自引：0，他引：1  
Laboratory assessment was made during maximal and submaximal exercise on 16 endurance trained male runners with asthma (aged 35 +/- 9 years) (mean +/- S.D.). Eleven of these asthmatic athletes had recent performance times over a half-marathon, which were examined in light of the results from the laboratory tests. The maximum oxygen uptake (VO2max) of the group was 61.8 +/- 6.3 ml kg-1 min-1 and the maximum ventilation (VEmax) was 138.7 +/- 24.7 l min-1. These maximum cardio-respiratory responses to exercise were positively correlated to the degree of airflow obstruction, defined as the forced expiratory volume in 1 s (expressed as a percentage of predicted normal). The half-marathon performance times of 11 of the athletes ranged from those of recreational to elite runners (82.4 +/- 8.8 min, range 69-94). Race pace was correlated with VO2max (r = 0.863, P less than 0.01) but the highest correlation was with the running velocity at a blood lactate concentration of 2 mmol l-1 (r = 0.971, P less than 0.01). The asthmatic athletes utilized 82 +/- 4% VO2max during the half-marathon, which was correlated with the %VO2max at 2 mmol l-1 blood lactate (r = 0.817, P less than 0.01). The results of this study suggest that athletes with mild to moderate asthma can possess high VO2max values and can develop a high degree of endurance fitness, as defined by their ability to sustain a high percentage of VO2max over an endurance race. In athletes with more severe airflow obstruction, the maximum ventilation rate may be reduced and so VO2max may be impaired. The athletes in the present study have adapted to this limitation by being able to sustain a higher %VO2max before the accumulation of blood lactate, which is an advantage during an endurance race. Therefore, with appropriate training and medication, asthmatics can successfully participate in endurance running at a competitive level.  相似文献   

5.
The purpose of the study was to relate three determinants of distance running success, (a) maximal oxygen consumption (VO2max), (b) ventilatory threshold (VT), and (c) running economy (RE), to actual running time in a 5-km race (ART). Twenty-four female runners (M age = 15.9 years) from four high school teams that competed at the Massachusetts All-State 5-km Cross Country Championship Meet and placed 1st, 7th, 19th, and 20th were tested in the laboratory. The mean VO2max of these runners was 61.7 ml.kg-1.min-1, HRmax 201 b.min-1, VEmax 100 L.min-1, and RER 1.10. The VT occurred at 79% of the VO2max, and HR of 184 b.min-1 (92% of HRmax). The velocity at VT (vVT) and velocity at VO2max (vVO2max) was correlated with ART, r(22) = .78 and .77 (p less than .001), respectively. The VO2 at VT and at maximal exercise was correlated with ART by r(22) = -.66 and -.69 (p less than .001), respectively. The VO2 at 215 m.min-1 (8 mph) was poorly related to ART, r(22) = -.05, p greater than .05. It was concluded that either of the derived variables vVT and vVO2max appear to explain significant variation in distance running performance among adolescent female cross country runners.  相似文献   

6.
Previous studies have reported strong correlations between 5-km performance times and maximal oxygen uptake (VO2 max) and also for running speeds equivalent to blood lactate concentrations of 4 mM. However, there is little information on the physiological responses of individuals during races over this distance. Therefore, the aim of the present study was to measure the physiological and metabolic responses of endurance trained male (n = 8) and female (n = 8) runners during a 5-km time trial using an instrumented treadmill. Performance times were 18.77 +/- 1.27 min for the men and 21.80 +/- 1.98 min for the women (P less than 0.01). The corresponding times on the athletics track were 17.68 +/- 0.39 min for the men (P less than 0.05) and 20.70 +/- 2.16 min for the women (N.S.). During the treadmill time trials, both the men and women were able to utilize approximately 90% VO2 max, 82% VE max, 98% HR max and produce similar concentrations of blood lactate. Although the physiological and metabolic responses of these endurance-trained men and women to 5-km treadmill running were similar, the faster running times recorded by the men in this study were the result of their higher VO2 max values.  相似文献   

7.
The aim of this study was to compare the evolution of oxygen uptake (VO2) in specifically trained runners during running tests based on the 400-, 800-, and 1500-m pacing strategies adopted by elite runners to optimize performance. Final velocity decreased significantly for all three distances, with the slowest velocity in the last 100 m expressed relative to the peak velocity observed in the 400 m (77%), 800 m (88%), and 1500 m (96%). Relative to the previously determined VO2max values, the respective VO 2peak corresponded to 94% (400 m) and 100% (800 and 1500 m). In the last 100 m, a decrease in VO2 was observed in all participants for the 400-m (15.6 ± 6.5%) and 800-m races (9.9 ± 6.3%), whereas a non-systematic decrease (3.6 ± 7.6%) was noted for the 1500 m. The amplitude of this decrease was correlated with the reduction in tidal volume recorded during the last 100 m of each distance (r = 0.85, P < 0.0001) and with maximal blood lactate concentrations after the three races (r = 0.55, P < 0.005). The present data demonstrate that the 800 m is similar to the 400 m in terms of decreases in velocity and VO2.  相似文献   

8.
Conconi et al. (1982) reported that an observed deviation from linearity in the heart rate-running velocity relationship determined during a field test in runners coincided with the ‘lactate threshold’. The aim of this study was to assess the validity of the original Conconi test using conventional incremental and constant-load laboratory protocols. Fourteen trained male distance runners (mean ± s : age 22.6 ±3.4 years; body mass 67.6±4.8 kg; peak [Vdot] O 2 66.3 ± 4.7 ml kg -1 min -1) performed a standard multi-stage test for determination of lactate turnpoint and a Conconi test on a motorized treadmill. A deviation from linearity in heart rate was observed in nine subjects. Significant differences were found to exist between running velocity at the lactate turnpoint (4.39 ± 0.20 ms -1) and at deviation from linear heart rate (5.08 ± 0.25 ms -1) (P < 0.01), and between heart rate at the lactate turnpoint (172 ± 10 beats min -1) and at deviation from linearity (186 ± 9 beats min -1) (P < 0.01). When deviation of heart rate from linearity was evident, it occurred at a systematically higher intensity than the lactate turnpoint and at approximately 95% of maximum heart rate. These results were confirmed by the physiological responses of seven subjects, who performed two constant-velocity treadmill runs at 0.14 ms -1 below the running velocity at the lactate turnpoint and that at which the heart rate deviated from linearity. For the lactate turnpoint trial, the prescribed 30 min exercise period was completed by all runners (terminal blood lactate concentration of 2.4 ± 0.5 mM ), while the duration attained in the trial for which heart rate deviated from linearity was 15.9 ± 6.7 min (terminal blood lactate concentration of 8.1 ± 1.8 mM). We concluded that the Conconi test is invalid for the non-invasive determination of the lactate turnpoint and that the deviation of heart rate from linearity represents the start of the plateau at maximal heart rate, the expression of which is dependent upon the specifics of the Conconi test protocol.  相似文献   

9.
The aim of the present study was to determine the repeatability of a running endurance test using an automated treadmill system that requires no manual input to control running speed. On three separate occasions, 7 days apart, 10 experienced male endurance-trained runners (mean age 32 years, s = 10; VO2peak 61 ml x kg(-1) x min(-1), s = 7) completed a treadmill time trial, in which they were instructed to run as far as possible in 60 min. The treadmill was instrumented with an ultrasonic feedback-controlled radar modulator that spontaneously regulated treadmill belt speed corresponding to the changing running speed of each runner. Estimated running intensity was 70% VO2peak (s = 11) and the distance covered 13.5 km (s = 2), with no difference in mean performances between trials. The coefficient of variation, estimated using analysis of variance, with participant and trial as main effects, was 1.4%. In summary, the use of an automated treadmill system improved the repeatability of a 60-min treadmill time trial compared with time trials in which speed is controlled manually. The present protocol is a reliable method of assessing endurance performance in endurance-trained runners.  相似文献   

10.
It is common for the physiological working capacity of a triathlete when cycling and running to be assessed on two separate days. The aim of this study was to establish whether an incremental running test to exhaustion has a negative effect after a 5 h recovery from an incremental cycling test. Eight moderately trained triathletes (age, 26.2 +/- 3.4 years; body mass, 67.3 +/- 9.1 kg; VO2max when cycling, 59 +/- 13 ml x kg x min(-1); mean +/- s) completed an incremental running test 5 h after an incremental cycling test (fatigue) as well as an incremental running test without previous activity (control). Maximum running speed, maximal oxygen uptake (VO2max) and the lactate threshold were determined for each incremental running test and correlated with the average speed during a 5 km run, which was performed immediately after a 20 km cycling time-trial, as in a sprint triathlon. There were no significant differences in maximum running speed, VO2max or the lactate threshold in either incremental running test (control or fatigue). Furthermore, good agreement was found for each physiological variable in both the control and fatigue tests. For the fatigue test, there were significant correlations between the average speed during a 5 km run and both VO2max expressed in absolute terms (r = 0.83) and the lactate threshold (r = 0.88). However, maximum running speed correlated most strongly with the average speed during a 5 km run (r = 0.96). The results of this study indicate that, under controlled conditions, an incremental running test can be performed successfully 5 h after an incremental cycling test to exhaustion. Also, the maximum running speed achieved during an incremental running test is the variable that correlates most strongly with the average running speed during a 5 km run after a 20 km cycling time-trial in well-trained triathletes.  相似文献   

11.
The purpose of the present study was to assess fitness and running performance in a group of recreational runners (men, n = 18; women, n = 13). ‘Fitness’ was determined on the basis of their physiological and metabolic responses during maximal and submaximal exercise. There were strong correlations between VO2 max and treadmill running speeds equivalent to blood lactate concentrations of 2 mmol 1‐1’ (V‐2 mM) or 4 mmol 1‐1 (V‐4 mM), ‘relative running economy’ and 5 km times (r = 0.84), but modest and non‐significant correlations between muscle fibre composition and running performance. The results of the submaximal exercise tests suggested that the female runners were as well trained as the male runners. However, the men still recorded faster 5 km times (19.20 ± 1.97 min vs 20.97 ± 1.70 min; P <0.05). Therefore the results of the present study suggest that the faster performance times recorded by the men were best explained by their higher VO2 max values, rather than their training status per se.  相似文献   

12.
The aim of this study was to assess the validity (Study 1) and reliability (Study 2) of a novel intermittent running test (Carminatti's test) for physiological assessment of soccer players. In Study 1, 28 players performed Carminatti's test, a repeated sprint ability test, and an intermittent treadmill test. In Study 2, 24 players performed Carminatti's test twice within 72 h to determine test-retest reliability. Carminatti's test required the participants to complete repeated bouts of 5 × 12 s shuttle running at progressively faster speeds until volitional exhaustion. The 12 s bouts were separated by 6 s recovery periods, making each stage 90 s in duration. The initial running distance was set at 15 m and was increased by 1 m at each stage (90 s). The repeated sprint ability test required the participants to perform 7 × 34.2 m maximal effort sprints separated by 25 s recovery. During the intermittent treadmill test, the initial velocity of 9.0 km · h(-1) was increased by 1.2 km · h(-1) every 3 min until volitional exhaustion. No significant difference (P > 0.05) was observed between Carminatti's test peak running velocity and speed at VO(2max) (v-VO(2max)). Peak running velocity in Carminatti's test was strongly correlated with v-VO(2max) (r = 0.74, P < 0.01), and highly associated with velocity at the onset of blood lactate accumulation (r = 0.63, P < 0.01). Mean sprint time was strongly associated with peak running velocity in Carminatti's test (r = -0.71, P < 0.01). The intraclass correlation was 0.94 with a coefficient of variation of 1.4%. In conclusion, Carminatti's test appears to be avalid and reliable measure of physical fitness and of the ability to perform intermittent high-intensity exercise in soccer players.  相似文献   

13.
Critical power is a theoretical concept that presumes there is a certain work‐rate which may be maintained without exhaustion. The extent to which critical power predicts running performance over varying distances has not been determined, and so the aim of this study was to correlate measurements of critical power in the laboratory to running performances in the field at 40 m and 1, 10 and 21.1 km in a group of 17 male longdistance runners (mean ± s.d. age = 31.7 ± 7.3 years). Each subject ran to exhaustion on the treadmill in the laboratory at six different speeds, ranging from 17 to 25 km h‐1. Least squares analyses were used to fit an exponential decay to the relationship between the running speed (y) versus time to exhaustion (x). Critical power was calculated as the running speed (y) coinciding with the asymptote or C parameter of the y = A‐e(‐Bx) + C relationship. The VO2 max was also measured in all subjects. For the data in the field, each subject was timed over 40 m and 1 km and participated in 10‐ and 21.1‐km races. The mean critical power of die subjects in this study was 18.5 ± 1.6 km h‐1. The test‐retest correlation coefficient for the determination of critical power was r = 0.99. The mean VO2 max, measured in a progressive exercise protocol starting at 13 km h‐1 and increasing by 1 km h‐1 every minute, was 59.2 ± 4.6 ml O2 kg‐1 min‐1. The 40‐m times ranged from 5.57 to 6.95 s, the 1‐km times from 2:46 to 3:55 min:s, the 10‐km times from 30:43 to 42:02 min:s and the 21‐km times from 67:00 to 95:45 min:s. Critical power predicted running times over 1 km (r = ‐0.75, P< 0.001), 10 km (r = ‐ 0.85, P< 0.00001) and 21.1 km (r = ‐ 0.79, P< 0.001) in this heterogeneous group of runners. The correlation coefficients for VO2 max and running performances were similar to the above at all distances. Even in the best relationship between critical power and the time taken to run 10 km, only 72% of the variation in the 10‐km running time could be accounted for by differences in critical power. While the test of critical power may be repeatable and correlate significantly with VO2 max (r = 0.77, P< 0.001), the measurement lacks the degree of specificity required to predict running performance in trained subjects of varying ability.  相似文献   

14.
Traditionally, it has been assumed that during middle-distance running oxygen uptake (VO2) reaches its maximal value (VO2max) providing the event is of a sufficient duration; however, this assumption is largely based on observations in individuals with a relatively low VO2max. The aim of this study was to determine whether VO2max is related to the VO2 attained (i.e. VO2peak) during middle-distance running on a treadmill. Fifteen well-trained male runners (age 23.3 +/- 3.8 years, height 1.80 +/- 0.10 m, body mass 76.9 +/- 10.6 kg) volunteered to participate in the study. The participants undertook two 800-m trials to examine the reproducibility of the VO2 response. These two trials, together with a progressive test to determine VO2max, were completed in a randomized order. Oxygen uptake was determined throughout each test using 15-s Douglas bag collections. Following the application of a 30-s rolling average, the highest VO2 during the progressive test (i.e. VO2max) was compared with the highest VO2 during the 800-m trials (i.e. VO2peak) to examine the relationship between VO2max and the VO2 attained in the 800-m trials. For the 15 runners, VO2max was 58.9 +/- 7.1 ml x kg(-1) x min(-1). Two groups were formed using a median split based on VO2max. For the high and low VO2max groups, VO2max was 65.7 +/- 3.0 and 52.4 +/- 1.8 ml x kg(-1) x min(-1) respectively. The limits of agreement (95%) for test-retest reproducibility for the VO2 attained during the 800-m trials were +/- 3.5 ml x kg(-1) x min(-1) for a VO2peak of 50.6 ml x kg(-1) x min(-1) (the mean VO2peak for the low VO2max group) and +/- 2.3 ml x kg(-1) x min(-1) for a VO2peak of 59.0 ml x kg(-1) x min(-1) (the mean VO2peak for the high VO2max group), with a bias in VO2peak between the 800-m runs (i.e. the mean difference) of 1.2 ml x kg(-1) x min(-1). The VO2peak for the 800-m runs was 54.8 +/- 4.9 ml x kg(-1) x min(-1) for all 15 runners. For the high and low VO2max groups, VO2peak was 59.0 +/- 3.3 ml x kg(-1) x min(-1) (i.e. 90% VO2max) and 50.6 +/- 2.0 ml x kg(-1) x min(-1) (i.e. 97% VO2max) respectively. The negative relationship (-0.77) between VO2max and % VO2max attained for all 15 runners was significant (P = 0.001). These results demonstrate that (i) reproducibility is good and (ii) that VO2max is related to the %VO2max achieved, with participants with a higher VO2max achieving a lower %VO2max in an 800-m trial on a treadmill.  相似文献   

15.
Effect of a carbohydrate mouthwash on running time-trial performance   总被引：1，自引：0，他引：1  
The aim of the present study was to determine the effect of a carbohydrate mouthwash on running time-trial performance. On two separate occasions, seven recreationally active males (VO2max 57.8 ml x kg(-1) x min(-1), s = 3.7) completed a preloaded (15 min at 65%VO2max) time-trial of 45 min in duration on a motorized treadmill. At 6-min intervals during the preload and time-trial, participants were given either a 6% maltodextrin, 3% lemon juice solution (carbohydrate trial) or a 3% lemon juice placebo mouthwash (placebo trial) in a double-blind, randomized crossover design. Heart rate, oxygen consumption (VO2), respiratory exchange ratio (RER), and ratings of perceived exertion (RPE) were measured during the preload, and blood glucose and lactate were measured before and after the preload and time-trial. There were no significant differences in distance covered between trials (carbohydrate: 9333 m, s = 988; placebo: 9309 m, s = 993). Furthermore, there were no significant between-trial differences in heart rate and running speed during the time-trial, or VO2, RER or RPE during the preload. Blood lactate and glucose increased as a result of the exercise protocol, with no between-trial differences. In conclusion, there was no positive effect of a carbohydrate mouthwash on running performance of approximately 1 h duration.  相似文献   

16.
The aim of this study was to establish the relationship between selected physiological variables of rowers and rowing performance as determined by a 2000 m time-trial on a Concept II Model B rowing ergometer. The participants were 13 male club standard oarsmen. Their mean (+/- s) age, body mass and height were 19.9+/-0.6 years, 73.1+/-6.6 kg and 180.5+/-4.6 cm respectively. The participants were tested on the rowing ergometer to determine their maximal oxygen uptake (VO2max), rowing economy, predicted velocity at VO2max, velocity and VO2 at the lactate threshold, and their velocity and VO2 at a blood lactate concentration of 4 mmol x l(-1). Percent body fat was estimated using the skinfold method. The velocity for the 2000 m performance test and the predicted velocities at the lactate threshold, at a blood lactate concentration of 4 mmol x l(-1) and at VO2max were 4.7+/-0.2, 3.9+/-0.2, 4.2+/-0.2 and 4.6+/-0.2 m x s(-1) respectively. A repeated-measures analysis of variance showed that the three predicted velocities were all significantly different from each other (P<0.05). The VO2max and lean body mass showed the highest correlation with the velocity for the 2000 m time-trial (r = 0.85). A stepwise multiple regression showed that VO2max was the best single predictor of the velocity for the 2000 m time-trial; a model incorporating VO2max explained 72% of the variability in 2000 m rowing performance. Our results suggest that rowers should devote time to the improvement of VO2max and lean body mass.  相似文献   

17.
The aim of this study was to assess the sensitivity of the lactate minimum speed test to changes in endurance fitness resulting from a 6 week training intervention. Sixteen participants (mean +/- s: age 23+/-4 years; body mass 69.7+/-9.1 kg) completed 6 weeks of endurance training. Another eight participants (age 23+/-4 years; body mass 72.7+/-12.5 kg) acted as non-training controls. Before and after the training intervention, all participants completed: (1) a standard multi-stage treadmill test for the assessment of VO2max, running speed at the lactate threshold and running speed at a reference blood lactate concentration of 3 mmol x l(-1); and (2) the lactate minimum speed test, which involved two supramaximal exercise bouts and an 8 min walking recovery period to increase blood lactate concentration before the completion of an incremental treadmill test. Additionally, a subgroup of eight participants from the training intervention completed a series of constant-speed runs for determination of running speed at the maximal lactate steady state. The test protocols were identical before and after the 6 week intervention. The control group showed no significant changes in VO2max, running speed at the lactate threshold, running speed at a blood lactate concentration of 3 mmol x l(-1) or the lactate minimum speed. In the training group, there was a significant increase in VO2max (from 47.9+/-8.4 to 52.2+/-2.7 ml x kg(-1) x min(-1)), running speed at the maximal lactate steady state (from 13.3+/-1.7 to 13.9+/-1.6 km x h(-1)), running speed at the lactate threshold (from 11.2+/-1.8 to 11.9+/-1.8 km x h(-1)) and running speed at a blood lactate concentration of 3 mmol x l(-1) (from 12.5+/-2.2 to 13.2+/-2.1 km x h(-1)) (all P < 0.05). Despite these clear improvements in aerobic fitness, there was no significant difference in lactate minimum speed after the training intervention (from 11.0+/-0.7 to 10.9+/-1.7 km x h(-1)). The results demonstrate that the lactate minimum speed, when assessed using the same exercise protocol before and after 6 weeks of aerobic exercise training, is not sensitive to changes in endurance capacity.  相似文献   

18.
The aim of this study was to assess the sensitivity of the lactate minimum speed test to changes in endurance fitness resulting from a 6 week training intervention. Sixteen participants (mean +/- s :age 23 +/- 4 years;body mass 69.7 +/- 9.1 kg) completed 6 weeks of endurance training. Another eight participants (age 23 +/- 4 years; body mass 72.7 +/-12.5 kg) acted as non-training controls. Before and after the training intervention, all participants completed: (1) a standard multi-stage treadmill test for the assessment of VO 2max , running speed at the lactate threshold and running speed at a reference blood lactate concentration of 3 mmol.l -1 ; and (2) the lactate minimum speed test, which involved two supramaximal exercise bouts and an 8 min walking recovery period to increase blood lactate concentration before the completion of an incremental treadmill test. Additionally, a subgroup of eight participants from the training intervention completed a series of constant-speed runs for determination of running speed at the maximal lactate steady state. The test protocols were identical before and after the 6 week intervention. The control group showed no significant changes in VO 2max , running speed at the lactate threshold, running speed at a blood lactate concentration of 3 mmol.l -1 or the lactate minimum speed.In the training group, there was a significant increase in VO 2max (from 47.9 +/- 8.4 to 52.2 +/- 2.7 ml.kg -1 .min -1 ), running speed at the maximal lactate steady state (from 13.3 +/- 1.7 to 13.9 +/- 1.6 km.h -1 ), running speed at the lactate threshold (from 11.2 +/- 1.8 to 11.9 +/- 1.8 km.h -1 ) and running speed at a blood lactate concentration of 3 mmol.l -1 (from 12.5 +/- 2.2 to 13.2 +/- 2.1 km.h -1 ) (all P ? 0.05). Despite these clear improvements in aerobic fitness, there was no significant difference in lactate minimum speed after the training intervention (from 11.0 +/- 0.7 to 10.9 +/- 1.7 km.h -1 ). The results demonstrate that the lactate minimum speed,when assessed using the same exercise protocol before and after 6 weeks of aerobic exercise training, is not sensitive to changes in endurance capacity.  相似文献   

19.
BackgroundSegment coordination variability (CV) is a movement pattern associated with running-related injuries. It can also be adversely affected by a prolonged run. However, research on this topic is currently limited. The purpose of this study was to investigate the effects of a prolonged run on segment CV and vertical loading rates during a treadmill half marathon.MethodsFifteen healthy runners ran a half marathon on an instrumental treadmill in a biomechanical laboratory. Synchronized kinematic and kinetic data were collected every 2 km (from 2 km until 20 km), and the data were processed by musculoskeletal modeling. Segment CVs were computed from the angle-angle plots of selected pelvis-thigh, thigh-shank, and shank-rearfoot couplings using a modified vector coding technique. The loading rate of vertical ground reaction force was also calculated. A one-way MANOVA with repeated measures was performed on each of the outcome variables to examine the main effect of running mileage.ResultsSignificant effects of running mileage were found on segment CVs (p ≤ 0.010) but not on loading rate (p = 0.881). Notably, during the early stance phase, the CV of pelvis frontal vs. thigh frontal was significantly increased at 20 km compared with the CV at 8 km (g = 0.59, p = 0.022). The CV of shank transverse vs. rearfoot frontal decreased from 2 km to 8 km (g = 0.30, p = 0.020) but then significantly increased at both 18 km (g = 0.05, p < 0.001) and 20 km (g = 0.36, p < 0.001).ConclusionAt the early stance, runners maintained stable CVs on the sagittal plane, which could explain the unchanged loading rate throughout the half marathon. However, increased CVs on the frontal/transverse plane may be an early sign of fatigue and indicative of possible injury risk. Further studies are necessary for conclusive statements in this regard.  相似文献   

20.
Abstract

The purpose of this study was to assess the relationships among ventilatory threshold T(vent), running economy and distance running performance in a group (N=9) of trained experienced male runners with comparable maximum oxygen uptake ([Vdot]O2 max). Maximal oxygen uptake and submaximal steady state oxygen uptake were measured using open circuit spirometry during treadmill exercise. Ventilatory threshold was determined during graded treadmill exercise using non-invasive techniques, while distance running performance was assessed by the best finish time in two 10-kilometer (km) road races. The subjects averaged 33.8 minutes on the 10km runs, 68.6 ml · kg -1 · min -1 for [Vdot]O2 max, and 48.1 ml · kg -1 · min -1 for steady state [Vdot]O2 running at 243 meters · min -1. The T(vent) (first deviation from linearity of [Vdot]E, [Vdot]CO 2 ) occurred at an oxygen consumption of 41.9 ml · kg -1 · min -1. The relationship between running economy and performance was r = .51 (p>0.15) and the relationship between T(vent) and performance was r = .94 (p < 0.001). Applying stepwise multiple linear regression, the multiple R did not increase significantly with the addition of variables to the T(vent); however, the combination of [Vdot]O2 max, running economy and T(vent) was determined to account for the greatest amount of total variance (89%). These data suggest that among trained and experienced runners with similar [Vdot]O2 max, T(vent) can account for a large portion of the variance in performance during a 10km race.  相似文献   

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