Aerobic high-intensity intervals improve VO2max more than moderate training

PURPOSE: The present study compared the effects of aerobic endurance training at different intensities and with different methods matched for total work and frequency. Responses in maximal oxygen uptake (VO2max), stroke volume of the heart (SV), blood volume, lactate threshold (LT), and running economy (CR) were examined. METHODS: Forty healthy, nonsmoking, moderately trained male subjects were randomly assigned to one of four groups:1) long slow distance (70% maximal heart rate; HRmax); 2)lactate threshold (85% HRmax); 3) 15/15 interval running (15 s of running at 90-95% HRmax followed by 15 s of active resting at 70% HRmax); and 4) 4 x 4 min of interval running (4 min of running at 90-95% HRmax followed by 3 min of active resting at 70%HRmax). All four training protocols resulted in similar total oxygen consumption and were performed 3 d.wk for 8 wk. RESULTS: High-intensity aerobic interval training resulted in significantly increased VO2max compared with long slow distance and lactate-threshold training intensities (P<0.01). The percentage increases for the 15/15 and 4 x 4 min groups were 5.5 and 7.2%, respectively, reflecting increases in V O2max from 60.5 to 64.4 mL x kg(-1) x min(-1) and 55.5 to 60.4 mL x kg(-1) x min(-1). SV increased significantly by approximately 10% after interval training (P<0.05). CONCLUSIONS:: High-aerobic intensity endurance interval training is significantly more effective than performing the same total work at either lactate threshold or at 70% HRmax, in improving VO2max. The changes in VO2max correspond with changes in SV, indicating a close link between the two.     

A new submaximal cycle ergometer test for prediction of VO2max

Maximal oxygen uptake (VO_2max) is an important, independent predictor of cardiovascular health and mortality. Despite this, it is rarely measured in clinical practice. The aim of this study was to create and evaluate a submaximal cycle ergometry test based on change in heart rate (HR) between a lower standard work rate and an individually chosen higher work rate. In a mixed population (n = 143) with regard to sex (55% women), age (21–65 years), and activity status (inactive to highly active), a model included change in HR per unit change in power, sex, and age for the best estimate of VO_2max. The association between estimated and observed VO_2max for the mixed sample was r = 0.91, standard error of estimate = 0.302 L/min, and mean measured VO_2max = 3.23 L/min. The corresponding coefficient of variation was 9.3%, a significantly improved precision compared with one of the most commonly used submaximal exercise tests, the Åstrand test, which in the present study was estimated to be 18.1%. Test–retest reliability analysis over 1 week revealed no mean difference in the estimated VO_2max (?0.02 L/min, 95% confidence interval: ?0.07–0.03). The new test is low‐risk, easily administered, and valid for a wide capacity range, and is therefore suitable in situations as health evaluations in the general population.     

Predictability of VO2 max from submaximal cycle ergometer and bench stepping tests.

The predictability of the maximal oxygen uptake (VO2 max) was studied using progressive and steady state protocols for cycle ergometry and bench stepping. The subjects were 12 healthy men, 23-58 years old. Prediction of VO2 max was made by extrapolation of the heart rate and O2 uptake at several sub-maximal work-loads using the least squares regression technique. The four sub-maximal procedures underestimated the measured VO2 max by between 0.13-0.55 l.min-1. The differences between the measured and predicted values were statistically significant for the tests involving the steady state protocol. The correlation coefficients between the predicted VO2 max for each of the submaximal tests, and the measured VO2 max, were significant at the .05 level. The results indicate that for a group of male subjects VO2 max can be predicted using the progressive protocol on either the cycle ergometer or stepping bench. Individual predictions are liable to considerable error.     

VO2max, protocol duration, and the VO2 plateau

PURPOSE: The purpose of this study was to compare VO2max, VO2-time slopes at the end of the protocol (last 30 s), and the presence of a VO2 plateau (VO2-time slope < 0.05 L.min(-1) during the last 30 s) across four protocol durations (5, 8, 12, and 16 min) during incremental cycling exercise to VO2max. METHODS: Eight male (23.8 +/- 3.2 yr) and eight female (26.0 +/- 8.9 yr) subjects of moderate to high fitness levels participated in the study. RESULTS: VO2max was significantly higher in men than in women for each protocol duration, with main effect means of 4.23 versus 2.84 L.min(-1), respectively. For women, VO2max did not differ between any protocol duration. For men, VO2max for the 8-min protocol (4.44 +/- 0.39 L.min(-1)) was significantly higher than for all other protocol durations. Analysis of covariance, using the highest VO2max as the covariate, removed all protocol-duration significance for men. The VO2 slope for the final 30 s of each test was significantly lower for the 16-min protocol compared with the 5-min protocol, for both men and women. The ventilation threshold across four protocols was similar, at approximately 76% of VO2max for both men and women. CONCLUSIONS: The protocol duration of tests to VO2max should be between 8 and 10 min for healthy, moderately to highly trained subjects.     

Effect of intensity of aerobic training on VO2max

PURPOSE: To determine whether various intensities of aerobic training differentially affect aerobic capacity as well as resting HR and resting blood pressure (BP). METHODS: Sixty-one health young adult subjects were matched for sex and VO2max and were randomly assigned to a moderate- (50% VO2 reserve (VO2R), vigorous (75% VO2R), near-maximal-intensity (95% VO2R), or a nonexercising control group. Intensity during exercise was controlled by having the subjects maintain target HR based on HR reserve. Exercise volume (and thus energy expenditure) was controlled across the three training groups by varying duration and frequency. Fifty-five subjects completed a 6-wk training protocol on a stationary bicycle ergometer and pre- and posttesting. During the final 4 wk, the moderate-intensity group exercised for 60 min, 4 d.wk the vigorous-intensity group exercised for 40 min, 4 d.wk and the near-maximal-intensity group exercised 3 d.wk performing 5 min at 75% VO2R followed by five intervals of 5 min at 95% VO2R and 5 min at 50% VO2R. RESULTS: VO2max significantly increased in all exercising groups by 7.2, 4.8, and 3.4 mL.min.kg in the near-maximal-, the vigorous-, and the moderate-intensity groups, respectively. Percent increases in the near-maximal- (20.6%), the vigorous- (14.3%), and the moderate-intensity (10.0%) groups were all significantly different from each other (P < 0.05). There were no significant changes in resting HR and BP in any group. CONCLUSION: When volume of exercise is controlled, higher intensities of exercise are more effective for improving VO2max than lower intensities of exercise in healthy, young adults.     

Resistive training can reduce coronary risk factors without altering VO2max or percent body fat

Eleven healthy, untrained males (age = 44 +/- 1 yr; range = 40 to 55 yr) were studied to determine the effects of 16 wk of high-intensity resistive training on risk factors for coronary artery disease. Lipoprotein-lipid profiles, plasma glucose and insulin responses during an oral glucose tolerance test, and blood pressure at rest were determined before and after training. The training program resulted in a 13% increase in high-density lipoprotein-cholesterol (39 +/- 2 vs 44 +/- 3 mg.dl-1, P less than 0.05), a 43% increase in high-density lipoprotein-cholesterol (7 +/- 2 vs 10 +/- 2 mg.dl-1, P less than 0.05), a 5% reduction in low-density lipoprotein cholesterol (129 +/- 5 vs 122 +/- 5 mg.dl-1, P less than 0.05), and an 8% decrease in the total cholesterol/high-density lipoprotein-cholesterol ratio (5.1 +/- 0.3 vs 4.7 +/- 0.3, P less than 0.01), despite no changes in VO2max, body weight, or percent body fat. Glucose-stimulated plasma insulin concentrations during oral glucose tolerance testing were significantly lower, and supine diastolic blood pressure was reduced (P less than 0.05) as a result of the training program. No changes in any of these variables occurred in a sedentary control group. These findings indicate that resistive training can lower risk factors for coronary artery disease independent of changes in VO2max, body weight, or body composition.     

Exercise mode affects the time to achieve VO2max without influencing maximal exercise time at the intensity associated with VO2max in triathletes

The objective of this study was to analyze, in triathletes, the possible influence of the exercise mode (running x cycling) on time to exhaustion (TTE) and oxygen uptake (VO2) response during exercise performed at the intensity associated with the achievement of maximal oxygen uptake (IVO2max). Eleven male triathletes (21.8 +/- 3.8 yr) performed the following tests on different days on a motorized treadmill and on a cycle ergometer: 1) incremental tests in order to determine VO2max and IVO2max and, 2) constant work rate tests to exhaustion at IVO2max to determine TTE and to describe VO2 response (time to achieve VO2max - TAVO2max, and time maintained at VO2max-TMVO2max). No differences were found in VO2max, TTE and TMVO2max obtained on the treadmill tests (63.7 +/- 4.7 ml . kg (-1) . min (-1); 324.6 +/- 109.1 s; 178.9 +/- 93.6 s) and cycle ergometer tests (61.4 +/- 4.5 ml . kg (- 1) . min (-1); 390.4 +/- 114.4 s; 213.5 +/- 102.4 s). However, TAVO2max was influenced by exercise mode (145.7 +/- 25.3 vs. 176.8 +/- 20.1 s; in treadmill and cycle ergometer, respectively; p = 0.006). It is concluded that exercise modality affects the TAVO2max, without influencing TTE and TMVO2max during exercise at IVO2max in triathletes.     

Nonexercise models for estimating VO2max with waist girth, percent fat, or BMI

Previously published nonexercise models using either percent fat or body mass index (BMI) as body composition measures provided valid estimates of VO2max. PURPOSE: This study was conducted to investigate the use of waist girth (WG) as a body composition surrogate in the nonexercise models and to compare the accuracy of nonexercise models that include WG, %fat, or BMI. METHODS: A total of 2417 men and 384 women were measured for VO2max by indirect calorimetry (RER > 1.1); age (yr); gender by M = 1, W = 0; self-report activity habit by the 11-point (0-10) NASA physical activity status scale (PASS); WG at the apex of the umbilicus; %fat by skinfolds; and BMI by weight (kg) divided by height squared (m). RESULTS: Three models were developed by multiple regression to estimate VO2max from age, gender, PASS, and either WG (R = 0.81, standard error of estimate (SEE) = 4.80 mL.kg.min), %fat (R = 0.82, SEE = 4.72 mL x kg(-1) x min(-1)), or BMI (R = 0.80, SEE = 4.90 mL x kg(-1) x min(-1)). Cross-validation by the PRESS technique confirmed these statistics. Accuracy of the models for predicting VO2max of subsamples was supported by constant errors (CE) < 1 mL.kg.min for subgroups of gender, age, PASS, and VO2max between 30 and 50 mL x kg(-1) x min(-1) (70% of the sample). CE were > 1 mL x kg(-1) x min(-1) for VO2max < 30 and > 50 mL x kg(-1) x min(-1). CONCLUSIONS: Waist girth is an acceptable surrogate for body composition in the nonexercise models. All models were similar in accuracy and valid for estimating VO2max of most adults, but with reduced accuracy at the extremes of fitness (VO2max < 30 and >50 mL x kg(-1) x min(-1)).     

Relationship of ergometer-specific VO2 max and muscle enzymes to blood lactate during submaximal exercise.

This study compared the relationship of maximum oxygen uptake and skeletal muscle enzyme activities to the submaximal exercise intensity eliciting 4 mM blood lactate (OBLA). Twelve subjects performed both cycle (Cy) and treadmill (Tr) submaximal exercise with step-wise increments each fourth minute. Blood lactate concentration and oxygen uptake (VO2) were determined during the final minute of each step. Peak VO2 during exhaustive exercise was also measured on each ergometer. Biopsies were taken from the gastrocnemius (gast) and vastus lateralis (vl) muscles as representatives of muscles recruited during Tr and Cy exercise, respectively. Citrate synthase (CS), phosphofructokinase (PFK), and lactate dehydrogenase (LDH) activities were assayed. Peak VO2 was 10% greater and the VO2 at OBLA was 16% greater during Tr compared to Cy exercise. The percent of peak VO2 at OBLA was 85% and 79% for Tr and Cy exercise, respectively. The absolute enzyme activities were not different in the two muscles, however the ratio LDH/CS was greater in the vl than in the gast. The results indicate that the absolute differences between Cy and Tr exercise in peak VO2 are not commensurate with the differences in the relative exercise intensity at which OBLA occurs.     

Effect of exercise-induced arterial O2 desaturation on VO2max in women

PURPOSE: We have recently reported that many healthy habitually active women experience exercise induced arterial hypoxemia (EIAH). We questioned whether EIAH affected VO2max in this population and whether the effect was similar to that reported in men. METHODS: Twenty-five healthy young women with widely varying fitness levels (VO2max, 56.7 +/- 1.5 mL x kg(-1) x min(-1); range: 41-70 mL x kg(-1) x min(-1)) and normal resting lung function performed two randomized incremental treadmill tests to VO2max (FIO2: 0.21 or 0.26) during the follicular phase of their menstrual cycle. Arterial blood samples were taken at rest and near the end of each workload during the normoxic test. RESULTS: During room air breathing at VO2max, SaO2 decreased to 91.8 +/- 0.4% (range 87-95%). With 0.26 FIO2, SaO2, at VO2max remained near resting levels and averaged 96.8 +/- 0.1% (range 96-98%). When arterial O2 desaturation was prevented via increased FIO2, VO2max increased in 22 of the 25 subjects and in proportion to the degree of arterial O2 desaturation experienced in normoxia (r = 0.88). The improvement in VO2max when systemic normoxia was maintained averaged 6.3 +/- 0.3% (range 0 to +15%) and the slope of the relationship was approximately 2% increase in VO2max for every 1% decrement in the arterial oxygen saturation below resting values. About 75% of the increase in VO2max resulted from an increase in VO2 at a fixed maximal work rate and exercise duration, and the remainder resulted from an increase in maximal work rate. CONCLUSIONS: These data demonstrate that even small amounts of EIAH (i.e., >3% delta SaO2 below rest) have a significant detrimental effect on VO2max in habitually active women with a wide range of VO2max. In combination with our previous findings documenting EIAH in females, we propose that inadequate pulmonary structure/function in many habitually active women serves as a primary limiting factor in maximal O2 transport and utilization during maximal exercise.     

Determination of the velocity associated with VO2max

PURPOSE: The theoretical velocity associated with VO2max (vVO2max) defined by Daniels (1985) is extrapolated from the submaximal VO2-velocity relationship. VO2 is generally determined by assuming that the aerobic response reacts like a linear first-order system at the beginning of square-wave exercise with a steady-state reached by the 4th minute. However, at supra-ventilatory threshold work rates, the steady state in VO2 is delayed or not attained. METHODS: The present study was carried out to compare three values for vVO2max determined with Daniels' method, but with VO2 either measured at the 4th minute (vVO2max4), the 6th minute (vVO2max6), or after the attainment of the true steady-state (vVO2maxSS). The metabolic response during square-wave exercise at each of the three vVO2max were also assessed. RESULTS: These velocities were significantly different (P < 0.05), but vVOmaxSS and vVO2max6 were highly correlated (r = 0.98; P < 0.05). Blood lactate concentrations measured after exercise at velocities very close to the three vVO2max were similar and the end-exercise VO2 were not different from VO2max, but the time required to elicit 95% VO2max during these three square-wave tests were significantly different. CONCLUSION: Therefore, when vVO2max is determined by extrapolation from the submaximal VO2-velocity relationships, submaximal VO2 should be measured beyond the 6th minute of square-wave exercise (at least if it takes 30 s to reach the desired velocity) to ensure that all vVO2max reported in future studies describe a similar quantitative index.     

Effect of reduced training volume on cardiac function, VO2 max, and running performance

This study examined the physiological effects of reducing training mileage in a veteran long distance runner while increasing exercise intensity. Variables measured included stroke volume, cardiac output, maximum oxygen uptake, ventilation threshold and performance time in a 10,000 m run. For 8 weeks, training mileage was reduced from 75.8 miles per week to 42.5 miles per week including interval training twice weekly. Following the specialized training, performance time was 10 seconds faster although VO2max and heart contractility had decreased. It was concluded that distance running performance can be maintained while considerably reducing training mileage and increasing exercise intensity twice a week.     

Effect of aerobic training quantity on the VO2 max of circumpubertal swimmers

Maximal oxygen uptake (VO2 max) was measured in 38 swimmers aged 10-14 years. Thirty of 38 boys participated in this study for at least 2 consecutive years. Group 1 consisted of 23 subjects (48 measures) who trained for 7 h/week while group 2 consisted of 15 subjects (27 measures) who trained for 14 h/week. In group 2, VO2 max normalized to body weight was significantly higher at 14 years of age than at 10, whereas the increase was nonsignificant during this period in group 1. The subjects of group 2 showed a large increase of VO2 max/kg body weight from the age of 13, which corresponded in this study to the age of peak height growth velocity. The differences between the two groups were statistically significant at both 13 (P less than 0.02) and 14 years of age (P less than 0.05). At 13 and 14, the most trained subjects also showed significantly higher (P less than 0.05) values of maximal oxygen pulse/kg body weight (VO2 max/kg/HR max). Maximal heart rate (HR max) was similar in the two groups between 10 and 14 years of age. Therefore, we conclude that an increase in a training program of the aerobic type induces a large increase in VO2 max from the age of peak height growth velocity. This is likely due to an increase in the stroke volume.     

New ideas on limitations to VO2max

VO2max indicates maximal oxidative metabolic capacity (unfit subjects) or maximal O2 supply (athletes). The latter reflects integration of all transport steps from air to cytochromes. Every step contributes something; the importance of each contribution varies with conditions. Cardiac output seems most important at sea level; at higher altitudes, lung/muscle diffusion are more critical.     

Effect of exercise intensity on relationship between VO2max and cardiac output

PURPOSE: The purpose of this study was to determine whether the maximal oxygen uptake (VO2max) is attained with the same central and peripheral factors according to the exercise intensity. METHODS: Nine well-trained males performed an incremental exercise test on a cycle ergometer to determine the maximal power associated with VO2max (pVO2max) and maximal cardiac output (Qmax). Two days later, they performed two continuous cycling exercises at 100% (tlim100 = 5 min 12 s +/- 2 min 25 s) and at an intermediate work rate between the lactate threshold and pVO2max (tlimDelta50 +/- 12 min 6 s +/- 3 min 5 s). Heart rate and stroke volume (SV) were measured (by impedance) continuously during all tests. Cardiac output (Q) and arterial-venous O2 difference (a-vO2 diff) were calculated using standard equations. RESULTS: Repeated measures ANOVA indicated that: 1) maximal heart rate, VE, blood lactate, and VO2 (VO2max) were not different between the three exercises but Q was lower in tlimDelta50 than in the incremental test (24.4 +/- 3.6 L x min(-1) vs 28.4 +/- 4.1 L x min(-1); P < 0.05) due to a lower SV (143 +/- 27 mL x beat(-1) vs 179 +/- 34 mL x beat(-1); P < 0.05), and 2) maximal values of a-vO2 diff were not significantly different between all the exercise protocols but reduced later in tlimDelta50 compared with tlim100 (6 min 58 s +/- 4 min 29 s vs 3 min 6 s +/- 1 min 3 s, P = 0.05). This reduction in a-vO2 diff was correlated with the arterial oxygen desaturation (SaO2 = -15.3 +/- 3.9%) in tlimDelta50 (r = -0.74, P = 0.05). CONCLUSION: VO2max was not attained with the same central and peripheral factors in exhaustive exercises, and tlimDelta50 did not elicit the maximal Q. This might be taken into account if the training aim is to enhance the central factors of VO2max using exercise intensities eliciting VO2max but not necessarily Qmax.     

Effect of training on VO2max, thigh strength, and muscle morphology in septuagenarian women

The purpose of this study was to determine the effects of a long-term (50 wk) combined aerobic-resistance training program on maximal oxygen consumption (VO2max, thigh strength, and vastus lateralis fiber morphology in healthy septuagenarian women (mean age = 72 +/- 6 yr). Subjects volunteered to be in either an exercise (Ex; N = 17) or control (Con; N = 10) group. Con subjects were 34% less active in winter than in summer, Ex subjects maintained their summer activity level on exercise days in winter. Initial, intermediate (20 wk), and final (50 wk) measurements were made for isokinetic knee extension/flexion strength; VO2max and morphological measurements from a muscle biopsy were made at the initial and final times only. Both groups gained in leg strength (Ex = +6.5%; Con = +7.8%; P less than or equal to 0.05) during the summer; in the winter the Ex group maintained leg strength and the Con group declined 12.2% (P less than or equal to 0.05). The fast-twitch muscle fiber area (Type IIb) increased 29% (P less than or equal to 0.001) in the Ex group and declined 26% (P = 0.014) in the Con group. VO2max increased only in the Ex group (16%; P less than 0.001). We conclude that healthy septuagenarian women can increase aerobic capacity, leg strength, and Type IIb muscle fiber area with a long-duration, combined aerobic-resistance exercise program.     

Reproducibility of time at or near VO2max during intermittent treadmill running

The purpose of this study was to determine the reproducibility of time at or above 90 % (t (90 % )VO (2max)) and 95 % (t (95 % )VO (2max)) maximal oxygen uptake during an intermittent treadmill run to exhaustion. Twenty-two distance runners (age 38.0 +/- 7.1 yrs) performed two identical incremental and two identical intermittent tests on four separate days. Respiratory exchange was measured continuously throughout each test by an automated open-circuit gas analysis system. The incremental test consisted of increases in treadmill speed every minute until volitional exhaustion. The highest averaged 30-s oxygen uptake (VO (2)) value was defined as VO (2max) and the minimum speed that elicited VO (2max) was defined as vVO (2max). The intermittent test consisted of 30-s work intervals ran at 105 % vVO (2max) interspersed by 30-s relief intervals ran at 60 % vVO (2max) and was continued until volitional exhaustion. The time that VO (2) was at or above 90 % and 95 % of the mean maximum values elicited during the two previous incremental tests was determined for the intermittent tests. The mean t (95 % )VO (2max) was 232 (SD 174) s and 244 (SD 195) s and the mean t (90 % )VO (2max) was 480 (SD 220) s and 488 (SD 252) s, for trial 1 and trial 2, respectively. Reproducibility statistics for t (95 % )VO (2max) and t (90 % )VO (2max), respectively, were: 95 % limits of agreement 12 +/- 227 s and 8 +/- 328 s; coefficient of variation 34.5 % and 24.5 %; and intraclass correlation coefficient 0.80 and 0.75. Statistical power analysis indicated that this level of reproducibility would allow mean differences of 15 - 20 % between intermittent training protocols to attain statistical significance in future experimental research, with sample sizes probably within the resources of most researchers.     

Validation of a new method for estimating VO2max based on VO2 reserve

PURPOSE: The American College of Sports Medicine's (ACSM) preferred method for estimating maximal oxygen consumption (VO2max) has been shown to overestimate VO2max, possibly due to the short length of the cycle ergometry stages. This study validates a new method that uses a final 6-min stage and that estimates VO2max from the relationship between heart rate reserve (HRR) and VO2 reserve. METHODS: A cycle ergometry protocol was designed to elicit 65-75% HRR in the fifth and sixth minutes of the final stage. Maximal workload was estimated by dividing the workload of the final stage by %HRR. VO2max was then estimated using the ACSM metabolic equation for cycling. After the 6-min stage was completed, an incremental test to maximal effort was used to measure actual VO2max. Forty-nine subjects completed a pilot study using one protocol to reach the 6-min stage, and 50 additional subjects completed a modified protocol. RESULTS: The pilot study obtained a valid estimate of VO2max (r = 0.91, SEE = 3.4 mL x min(-1) x kg-1) with no over- or underestimation (mean estimated VO2max = 35.3 mL x min(-1) x kg(-1), mean measured VO2max = 36.1 mL x min(-1) x kg(-1)), but the average %HRR achieved in the 6-min stage was 78%, with several subjects attaining heart rates considered too high for submaximal fitness testing. The second study also obtained a valid estimate of VO2max (r = 0.89, SEE = 4.0 mL x min(-1) x kg(-1)) with no over- or underestimation (mean estimated VO2max = 36.7 mL x min(-1) x kg(-1), mean measured VO2max = 36.9 mL x min(-1) x kg(-1), and the average %HRR achieved in the 6-min stage was 64%. CONCLUSIONS: A new method for estimating VO2max from submaximal cycling based on VO2 reserve has been found to be valid and more accurate than previous methods.     

采用100%vVO_2max恒定负荷运动测定VO_2max可行性分析

目的:探讨利用恒定负荷运动方式测定最大摄氧量(VO2max)的可行性,以寻找相对简单易行且相关度较高的测试方法。方法:首先运用递增负荷运动方式测定武汉体育学院195名男大学生的VO2max,确定100%最大摄氧量速度(100%vVO2max)范围(本实验中95%的受试者100%vVO2max为16~18km·h-)。然后令1其中15名受试者分别以100%vVO2max、110%vVO2max恒定负荷运动至力竭,记录3次运动至力竭的时间(Tlim)并进行统计,分析3种运动负荷下Tlim的相关性。结果:①递增负荷与100%vVO2max恒定负荷运动所测得的VO2max无显著性差异(P>0.05),其中,15s取值时递增负荷与100%vVO2max恒定负荷运动所测得的VO2max相关系数为0.77,30s取值时两者的相关系数为0.76,相关性非常显著(P<0.01)。②递增负荷与100%vVO2max及110%vVO2max恒定负荷运动至力竭的时间Tlim分别为596.87±61.48s、214.0±77.65s和144.6±53.12s,三者两两相比均具有非常显著的差异(P<0.01),且100%和110%vVO2max恒定负荷下Tlim值显著相关,相关系数r=0.80(P<0.01)。结论:采用恒定负荷运动测定VO2max具有时间短、与递增负荷测试结果相关度较高及测试相对便捷等优点,适于在基层社区和学校应用。