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1.
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   

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 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   

3.
The influences of growth, training and various training methods were investigated by analysing long‐term training effects in young cross‐country and biathlon skiers (n = 129). Some athletes (n = 49) were studied six times in three years and some at least once a year during a four year period (n = 48). During three summer training periods skiers emphasized either intensive training or distance training or continued to train normally. The results indicated that maximal oxygen uptake (VO2 max) and heart volume increased between 15 and 20 years of age and the most significant changes in heart volume were observed between 16 and 18 years of age. International level skiers were able to increase their VO2 max and heart volume even after 20 years of age. Anaerobic threshold (AT, ml kg‐1 min‐1) increased like VO2 max but when expressed as a percentage of VO2 max, the AT was similar in every age group over 16 years of age. Intensive training at the intensity of anaerobic threshold or higher was observed to be most effective in producing improvements in VO2 max. Low‐intensity distance training was more effective in producing improvements in anaerobic threshold.  相似文献   

4.
Abstract

The effect of caffeine ingestion on submaximal endurance performance of 15 females and 13 males was investigated. After completing a [Vdot]O 2 max test, each subject performed two submaximal cycling tests at approximately 75% of [Vdot]O 2 max to exhaustion. For the caffeine (C) trials, 300 mg of caffeine was added to 250 ml of decaffeinated coffee and ingested one hour prior to the exercise. The decaffeinated (D) trial involved consuming 250 ml of decaffeinated coffee an hour prior to the test. The C and D trials were administered randomly using a standard double blind design. Physiological parameters were monitored each 9, 10, and 11 minute intervals throughout each trial and averaged. As expected the [Vdot]O 2 (L · min ?1 ), [Vdot]E and work outputs (kgm) were significantly (p < 0.001) higher for the males than the females. All other variables, time to exhaustion, [Vdot]O 2 (ml · kg · min ?1 ), R, HR, and rating of perceived exertion (RPE) were not significantly (p > 0.05) different between the sexes for either the C or D trials. Time to exhaustion was 14.4 and 3.1% longer for the C trials for the females and males, respectively, however these increases were not significant (p > 0.05). Furthermore, there were no significant differences (p > 0.05) for any of the measured variables during successive 10 minute work intervals between the C and D trials for either sex. These results do not support the general use of caffeine in moderate amounts as an ergogenic aid for either males or females, but from a practical point it appears that caffeine may have an ergogenic effect on specific individuals.  相似文献   

5.
Abstract

The purpose of this study was to investigate selected physiological changes that occurred with distance training in teenage females. Two groups of untrained teenage females were matched on [Vdot]O2 max, percent utilization of [Vdot]O 2 @ 9.66 km/hr, peak heart rate, and percent body fat. One group served as control (n = 9) while the other (n =10) underwent a 20-week training program designed to gradually increase the subjects' average mileage from 0 to 32.2 km per week. At the end of the 20 weeks, a MANOVA revealed significant mean differences within the trained group and no significant mean differences within the control group. The univariate analysis revealed that significant (p <0.05) mean differences found within the training group were for [Vdot]O 2 max (45.1 vs. 49.3 ml · kg –1 · min –1 ), percent utilization of [Vdot]O 2 @9.66 km/hr (76.5% vs. 67.5%), and economy VO 2 @9.66 km/hr (34.5vs.33.2 ml · kg –1 · min –1 ). Of the variables which exhibited significant training effects, percent utilization of [Vdot]O 2 max showed the greatest relative change, a 12.2% decrease, with [Vdot]O 2 max showing a 9.3% increase. The posttest results were similar to the research literature for training effects found for males and other age groups.  相似文献   

6.
Non-exercise equations developed from self-reported physical activity can estimate maximal oxygen uptake (VO2max) as well as sub-maximal exercise testing. The International Physical Activity Questionnaire is the most widely used and validated self-report measure of physical activity. This study aimed to develop and test a VO2max estimation equation derived from the International Physical Activity Questionnaire–Short Form. College-aged males and females (n = 80) completed the International Physical Activity Questionnaire–Short Form and performed a maximal exercise test. The estimation equation was created with multivariate regression in a gender-balanced subsample of participants, equally representing five levels of fitness (n = 50) and validated in the remaining participants (n = 30). The resulting equation explained 43% of the variance in measured VO2max (standard error of estimate = 5.45 ml·kg–1·min–1). Estimated VO2max for 87% of individuals fell within acceptable limits of error observed with sub-maximal exercise testing (20% error). The International Physical Activity Questionnaire–Short Form can be used to successfully estimate VO2max as well as sub-maximal exercise tests. Development of other population-specific estimation equations is warranted.  相似文献   

7.
The hypothesis that endurance training impairs sprinting ability was examined. Eight male subjects undertook a 30‐s sprint test on a cycle ergometer before and after 6 weeks of cycling training for endurance. Maximum oxygen uptake (VO2 max) and submaximum endurance were determined to evaluate the influence of the training regimen on endurance performance. Endurance was defined as the time to exhaustion at a relative exercise intensity of 85% VO2 max. Maximum oxygen uptake was increased by 18% post‐training (3.29 ± 0.291 min–1 versus 3.89±0.491 min–1; P <0.01), but endurance at the same absolute work rate as pre‐training was increased by more than 200% (32.2 ±11.4 min versus 97.8 + 27.3 min; P <0.01). These improvements were accompanied by changes in the cardiovascular and metabolic responses to standard, submaximum exercise. Despite the improvements in endurance, neither performance during the cycle sprint test nor the increase in blood lactate concentration during the sprint was influenced by endurance training. For short‐term cycling training, these findings reinforce the concept of training specificity whilst demonstrating that decrements in sprint performance are not a necessary consequence of improved endurance.  相似文献   

8.
Cardiorespiratory and body composition changes were evaluated in 25 sedentary females, aged 18 to 30 years, following 12 weeks of aerobic dance training (3 days a week, 45 min a session). Fifteen subjects, from the same population, comprised a control group: they maintained their normal activity and dietary habits over the course of the study. Analysis of variance of the values for selected cardiorespiratory responses revealed that the aerobic dance programme produced training effects in the experimental group. These training effects were indicated by significant improvements in O2 pulse, V E, heart rate and perceived exertion during submaximal exercise. Significant improvements were also noted in VO2 max, maximal O2pulse, V E max, maximal heart rate and maximal running time on the treadmill. Additionally, increases in lean body mass and body density, together with decreases in percentage body fat and the sum of four skinfold thicknesses were found to be significant for the experimental group. No significant improvements in any of these variables were found for the control group. It was concluded that this 12‐week aerobic dance programme was successful in promoting beneficial changes in cardiorespiratory fitness and body composition.  相似文献   

9.
The purpose of this study was to determine whether the sequence of strength training before endurance training (ST/ET) is more or less effective than endurance training followed by strength training (ET/ST). Twenty‐three females and 11 males were assigned to one of three groups: ST/ET (n= 15), ET/ST (n= 15) or control (n = 4). The 7‐week training programme consisted of strength training using 10 exercises for two sets of 3–12 repetitions and running for 20–25 min at 60–90% of heart rate reserve. Maximal oxygen uptake (VO2 max) was measured during a graded treadmill test, and muscular strength was assessed using one‐repetition maximum tests for the bench press (BP), shoulder press (SP), arm curl (AC) and leg press (LP). The VO2 max significantly (P < 0.05) increased 6.7 and 6.2% for the ST/ET and ET/ST groups, respectively. There was no significant (P > 0.05) difference between the two experimental groups. Muscular strength significantly (P <0.05) improved by 15.2% (BP), 16.6% (SP), 17.2% (AC) and 11.9% (LP) for the ST/ET group and 19.9% (BP), 24.1% (SP), 20.9% (AC) and 14.0% (LP) for the ET/ST group. There were no significant (P > 0.05) differences between the two experimental groups for the BP, AC and LP; however, the ET/ST group increased (P < 0.05) SP strength more than the ST/ET group. In conclusion, adaptations to a combination of short‐term endurance and strength training as assessed by VO2 max and BP, AC and LP strength appear to be independent of whether endurance training occurs prior to or following strength training.  相似文献   

10.
In order to determine the influence of two artificially induced alkalotic states on the ability to perform maximal exercise, six male subjects (mean age, 22.0 years; mean height, 176.8 cm; mean weight, 69.1 kg; mean VO2 max, 3.83 1 min‐1) were studied during three experimental trials. The subjects performed six 60‐s cycling bouts, at a work rate corresponding to 125% VO2 max, with 60 s recovery between work bouts; these regimes were performed 1 h after the ingestion of a solution containing either: I, placebo; II, NaHCO3 in a dosage of 0.15 g per kg body weight; or III, NaHCO3 0.30 g per kg body weight. The sixth work bout was continued until the pedal velocity dropped below 50 rev min‐1. Total work done for the entire work period was calculated. Blood samples were taken from a forearm vein prior to the exercise bouts for analysis of pH and HCO3. The results showed a significant pre‐exercise difference in pH and HCO3 for all conditions (P<0.01). In conditions where artificial alkalosis had been achieved prior to exercise there was significant increase in the work produced: I, 121.6 kJ; II, 133.1 kJ; III, 133.5 kJ (P<0.05). The time to fatigue in the sixth bout was also significantly increased: I, 74.7 s; II, 111.0 s; III, 106.0 s (P<0.05). There were no significant differences between conditions II and III. Thus augmentation of the bicarbonate reserves has a significant positive effect on the energy metabolism in interval‐type exercise, leading to an increase in the work done and in the time to fatigue. However, an increasing level of alkalosis had no additional benefit, suggesting that maximum contribution to buffering capacity had been achieved at the lower dose.  相似文献   

11.
Abstract

Eight male and eight female runners were matched on performance in a 24.2 km (15 mile) road race (X time ± SD = 115.1 ± 2.2 min for females, 115.8 ± 3.2 min for males). All subjects completed a graded treadmill run during which [Vdot]O 2 and heart rate (HR) were monitored at several submaximal running speeds and at maximal exercise. Blood samples, collected at rest and 3 min after maximal exercise, were analyzed for hematocrit and hemoglobin (Hb), lactic acid (LA) and 2,3-diphosphoglyceric acid (2,3-DPG) concentrations. Body composition was assessed via hydrostatic weighing. Group comparisons revealed that the males were taller, heavier, and higher in Hb than the females (p < .05). The sexes did not differ significantly in percentage of body fat or in [Vdot]O 2 (ml · kg –1 · min –1 ), HR, respiratory exchange ratio, or ventilatory equivalent of oxygen during submaximal running or at maximal exercise (p > .05). 2,3-DPG was higher in the females when expressed relative to Hb (p < .05). These data indicate that female and male distance runners of equal performance levels are very similar in body composition and in metabolic and cardiorespiratory responses to exercise. The higher Hb observed in males may have been offset in part by the females' higher 2,3-DPG/Hb ratio.  相似文献   

12.
The purpose of this study was to develop a step test with a personalized step rate and step height to predict cardiorespiratory fitness in 80 college-aged males and females using the self-reported perceived functional ability scale and data collected during the step test. Multiple linear regression analysis yielded a model (R = 0.90, SEE = 3.43 mL·kg?1·min?1) that included gender, body mass, perceived functional ability, step rate, and recovery heart rate. Based on the standardized β-weights, gender explained the largest proportion of variance in VO2max values followed by perceived functional ability. The cross validation predicted residual sum of squares statistics show minimal shrinkage (RPRESS = 0.88, SEEPRESS = 3.57 mL·kg?1·min?1) in the accuracy of the regression model. This study provides a model to predict VO2max from non-exercise data and data collected during an individualized multistage step test that is accurate, time-efficient, and easy to administer.  相似文献   

13.
The purpose of this study was to test the hypothesis that increased availability of blood‐borne glucose would improve endurance after carbohydrate loading. A single‐leg exercise model was employed, taking advantage of the fact that supercompensation of muscle glycogen occurs only in a previously exercised limb. Endurance time to exhaustion at 70% of maximal oxygen uptake (VO2max) was determined for 11 males and three females who were then allocated to a control group or a high‐carbohydrate (CHO) group. For 3 days following Test 1 the control group maintained a prescribed normal diet whilst the CHO group increased the proportion of energy derived from carbohydrate (62.1 ± 4.3% cf. 43.9 ± 2.0%, P < 0.01). The endurance test was then repeated using the leg that was inactive during Test 1. Endurance time was increased on Test 2 (123.7 ± 43.2 min cf. 98.5 ± 21.9 min, P <0.05 one‐tailed test) for the CHO group but not for the control group (101.8 ± 21.7 min cf. 107.5 ± 9.1 min, NS). There was no indication of enhanced carbohydrate metabolism during Test 2 for the CHO group but mean heart rate was lower during Test 2 than during Test 1 (145 ± 14 beat min ‐1 cf. 152 ± 12 beat min ‐1, P<0.05). These results suggest that the prior consumption of a high‐carbohydrate diet improves endurance during high‐intensity cycling with a limb with normal muscle glycogen concentration.  相似文献   

14.
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   

15.
The purpose of this study was to develop a multiple linear regression model to predict treadmill VO2max scores using both exercise and non-exercise data. One hundred five college-aged participants (53 male, 52 female) successfully completed a submaximal cycle ergometer test and a maximal graded exercise test on a motorized treadmill. The submaximal cycle protocol required participants to achieve a steady-state heart rate equal to at least 70% of age-predicted maximum heart rate (220-age), while the maximal treadmill graded exercise test required participants to exercise to volitional fatigue. Relevant submaximal cycle ergometer test data included a mean (±SD) ending steady-state heart rate and ending workrate equal to 164.2 ± 13.0 bpm and 115.3 ± 27.0 watts, respectively. Relevant non-exercise data included a mean (±SD) body mass (kg), perceived functional ability score, and physical activity rating score of 74.2 ± 15.1, 15.7 ± 4.3, and 4.7 ± 2.1, respectively. Multiple linear regression was used to generate the following prediction of (R = .91, standard error of estimates (SEE) = 3.36 ml·kg?1·min?1): VO2max = 54.513 + 9.752 (gender, 1 = male, 0 = female) – .297 (body mass, kg) + .739 (perceived functional ability, 2–26) + .077 (work rate, watts) – .072 (steady-state heart rate). Each predictor variable was statistically significant (p < .05) with beta weights for gender, body mass, perceived functional ability, exercise workrate, and steady-state heart rate equal to .594, –.544, .388, .305, and –.116, respectively. The predicted residual sums of squares (PRESS) statistics reflected minimal shrinkage (RPRESS = .90, SEEPRESS = 3.56 ml·kg?1·min?1) for the multiple linear regression model. In summary, the submaximal cycle ergometer protocol and accompanying prediction model yield relatively accurate VO2max estimates in healthy college-aged participants using both exercise and non-exercise data.  相似文献   

16.
Investigations in the 1990s evaluated the influence of breathing assemblies on respiratory variables at rest and during exercise; however, research on new models of breathing assemblies is lacking. This study compared metabolic gas analysis data from a mouthpiece with a noseclip (MOUTH) and a face mask (MASK). Volunteers (7 males, 7 females; 25.1 ± 2.7 years) completed two maximal treadmill tests within 1 week, one MOUTH and one MASK, in random order. The difference in maximal oxygen consumption (VO2max) between MOUTH (52.7 ± 11.3 ml · kg?1 · min?1) and MASK (52.2 ± 11.7 ml · kg?1 · min?1) was not significant (P = 0.53). Likewise, the mean MOUTH–MASK differences in minute ventilation (VE), fraction of expired oxygen (FEO2) and carbon dioxide (FECO2), respiration rate (RR), tidal volume (Vt), heart rate (HR), and rating of perceived exertion (RPE) at maximal and submaximal intensities were not significant (P > 0.05). Furthermore, there was no systematic bias in the error scores (r = ?0.13, P = 0.66), and 12 of the 14 participants had a VO2max difference of ≤3 ml · kg?1 · min?1 between conditions. Finally, there was no clear participant preference for using the MOUTH or MASK. Selection of MOUTH or MASK will not affect the participant’s gas exchange or breathing patterns.  相似文献   

17.
In order to assess the possible occurrence of acute haemolysis with prolonged exertion, serum haptoglobin levels were determined from venous blood samples collected from eight male runners immediately preceding (PreRH), immediately following (PRH1), and 6 h following (PRH2) completion of a marathon road race. The subjects’ mean age, percentage of body fat, and maximum oxygen uptake (VO2max) were 46 ± 9 years, 12.1 ± 3.4% and 54.9 ± 8.4 ml kg‐1 min‐1, respectively. The mean race finish time for the subjects was 3:35 ± O: 18 h:min. The PreRH, PRH1 and PRH2 averaged 129 ± 18, 97 ± 48 and 86 ± 35 mg dl‐1 respectively. Significant differences of –32.5 mg dl‐1 between PreRH versus PRH1 and –42.5 mg dl‐1 between PreRH versus PRH2 were found. The difference between PRH1 and PRH2 of –10.6 mg dl‐1 was not significant. No significant correlations were found between the decreases in serum haptoglobin and VO2max or race finish time. The data suggest the occurrence of an acute haemolysis with performance of the marathon road race.  相似文献   

18.
To adhere to the principle of “exercise specificity” exercise testing should be completed using the same physical activity that is performed during exercise training. The present study was designed to assess whether aerobic step exercisers have a greater maximal oxygen consumption (max VO2) when tested using an activity specific, maximal step exercise test (SET; arms and legs) versus a maximal running test (legs only). Female aerobic step exercisers (N=18; 20.7 ± 1.5 years) performed three maximal graded exercise tests (GXTs): 2 SETs; 1 treadmill test (TMT). The SET consisted of six 3-min progressive stages of alternate lead, basic step, basic step with biceps curls, knee raise with pull-down, repeater knee with pull-down, lateral lunge with pull-down, and side squat with shoulder presses. Stepping rate was 32 steps· min?1 on an 8-in (20.32 cm) step for stages 1–3, and a 10-in (25.4 cm) step for stages 4–6. Submaximal and maximal heart rate (HR) and oxygen consumption (VO2) were recorded at the end of each stage. Test–retest reliability for the first five stages of the SET ranged from .91 to .97 for HR, and from .84 to .96 for VO2. Maximal HR was significantly greater (p =.0001) for the SET (200 ± 6.2 beats·min?1) as compared to the TMT (193 ± 7.9 beats·min?1). No significant difference was found for max VO2 (42.9 ± 8.5, 41.2 ± 5.9 ml·kg?1·min?1, p =.14). The SET was a valid and reliable protocol for assessing responses of these aerobic step exercisers; however, max VO2 from a TMT did not differ significantly from the SET. Conversely, max HR obtained from the criterion TMT was 7 beats·min?1 lower than from the SET. If a training HR for step exercise (arms and legs exercise) is prescribed based on the max HR from treadmill exercise (legs only), then the training HR should be calculated from a TMT max HR that has been increased by 7 beats·min?1 to obtain an intensity of step exercise comparable to that of running.  相似文献   

19.
Abstract

The purpose of this study was to develop a regression equation to predict maximal oxygen uptake (VO2max) based on nonexercise (N-EX) data. All participants (N= 100), ages 18–65 years, successfully completed a maximal graded exercise test (GXT) to assess VO2max (M= 39.96 mL·kg -1· min -1 , SD = 9.54). The N-EX data collected just before the maximal GXT included the participant's age; gender; body mass index (BMI); perceived functional ability (PFA) to walk, jog, or run given distances; and current physical activity (PA-R) level. Multiple linear regression generated the following N-EX prediction equation (R = .93, SEE = 3.45 mL·kg -1· min -1 , %SEE= 8.62): VO2max (mL·kg -1· min -1 ) = 48.0730 + (6.1779 x gender; women = 0, men = 1) – (0.2463 x age) – (0.6186 x BMI) + (0.7115 x PFA) + (0.6709 x PA-R). Cross validation using PRESS (predicted residual sum of squares) statistics revealed minimal shrinkage (R p = .91 and SEE p = 3.63 mL·kg -1· min -1 ); thus, this model should yield acceptable accuracy when applied to an independent sample of adults (ages 18–-65 years) with a similar cardiorespiratory fitness level. Based on standardized β-weights, the PFA variable (0.41) was the most effective at predicting VO2max followed by age (-0.34), gender (0.33), BMI (-0.27), and PA-R (0.16). This study provides a N-EX regression model that yields relatively accurate results and is a convenient way to predict VO2max in adult men and women.  相似文献   

20.
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