Metabolic and cardiorespiratory responses to the performance of Wing Chun and T'ai Chi Chuan exercise

The primary purpose of this study was to examine the metabolic and cardiorespiratory responses to the continuous performance of Wing Chun and T'ai Chi Chuan exercise. No significant differences in VO2max or HRmax obtained during treadmill exercise were found between the practitioners of the two styles. Average values for oxygen uptake (VO2) were 23.3 +/- 7.5 ml.kg-1.min-1 (6.6 METS) and 16.0 +/- 3.9 ml.kg-1.min-1 (4.6 METS) for Wing Chun and T'ai Chi Chuan exercise, respectively. Mean heart rates obtained during exercise were 137 +/- 25 beats.min-1 for Wing Chun and 116 +/- 22 beats.min-1 for T'ai Chi Chuan exercise. These exercise values corresponded to 52.4% of VO2max and 70.5% of HRmax for Wing Chun and only 36.4% of VO2max and 59.8% of HRmax for T'ai Chi Chuan exercise. Thus, only the continuous performance of Wing Chun exercise elicited VO2 and HR responses that would be expected to bring about a cardiorespiratory training effect in subjects with a relatively low initial VO2max. The ventilatory equivalent for oxygen (VE/VO2) obtained during T'ai Chi Chuan exercise (21.7) was significantly lower than for Wing Chun exercise (24.2), suggesting that T'ai Chi practitioners utilize efficient breathing patterns during exercise. Both Wing Chun and T'ai Chi Chuan styles may have a small static component that produces a slightly elevated heart rate relative to metabolic load when compared to traditional aerobic activities. However, the effect was not severe and these forms of exercise should not be considered dangerous for individuals at high risk for cardiovascular disease.     

Accuracy of polar S410 heart rate monitor to estimate energy cost of exercise

PURPOSE: The purpose of this study was to examine the accuracy of the Polar S410 for estimating gross energy expenditure (EE) during exercise when using both predicted and measured VO2max and HRmax versus indirect calorimetry (IC). METHODS: Ten males and 10 females initially had their VO2max and HRmax predicted by the S410, and then performed a maximal treadmill test to determine their actual values. The participants then performed three submaximal exercise tests at RPE of 3, 5, and 7 on a treadmill, cycle, and rowing ergometer for a total of nine submaximal bouts. For all submaximal testing, the participant had two S410 heart rate monitors simultaneously collecting data: one heart rate monitor (PHRM) utilized their predicted VO2max and HRmax, and one heart rate monitor (AHRM) used their actual values. Simultaneously, EE was measured by IC. RESULTS: In males, there were no differences in EE among the mean values for the AHRM, PHRM, and IC for any exercise mode (P > 0.05). In females, the PHRM significantly overestimated mean EE on the treadmill (by 2.4 kcal x min(-1)), cycle (by 2.9 kcal x min(-1)), and rower (by 1.9 kcal x min(-1)) (all P < 0.05). The AHRM for females significantly improved the estimation of mean EE for all exercise modes, but it still overestimated mean EE on the treadmill (by 0.6 kcal x min(-1)) and cycle (by 1.2 kcal x min(-1)) (P < 0.05). CONCLUSION: When the predicted values of VO2max and HRmax are used, the Polar S410 HRM provides a rough estimate of EE during running, rowing, and cycling. Using the actual values for VO2max and HRmax reduced the individual error scores for both genders, but in females the mean EE was still overestimated by 12%.     

Aerobic fitness in a population of independently living men and women aged 55-86 years

PURPOSE: The purpose was to examine, for a subset of a large random survey of men and women, the age-related changes in the parameters of aerobic function, maximal oxygen consumption (VO2max), and ventilatory threshold (T(VE)). METHODS: A "ramp-like" treadmill protocol was designed to measure VO2max and T(VE) on a total of 298 subjects (152 men and 146 women), aged 55-86 yr. RESULTS: Data for VO2max (and HRmax) and T(VE) by 5-yr age groups provide "normative" results. Age-related declines in VO2max and T(VE) were fit by a linear model; however, age explained at most 37% of the variance across ages 55-86 yr. In this restricted age range, the rate of decline in VO2max, in both men (-0.034 L x min(-1) x yr(-1)) and women (-0.019 L x min(-1) x yr(-1)), was similar to that of previous reports for linear regression with age. Men, but not women, showed a decrease in body mass across age. Thus, the decline in VO2max expressed relative to body mass was similar in men (0.31 mL x kg(-1) x min(-1) x yr(-1)) and women (0.25); however, across this older age the decline is slower than noted for younger groups. The minimum level of aerobic power compatible with an independent life at age 85 yr was approximately 18 mL x kg(-1) x min(-1) in men and 15 mL x kg(-1) x min(-1) in women. Regression analysis showed HRmax across this age span is not well predicted by age. T(VE) across age declined at about one-half the rate of the VO2max, and in older age was approximately 85% of the VO2max. CONCLUSION: The study provides "normative" cardiorespiratory function data of a random sample of independently living men and women aged 55-86 yr.     

Reliability and validity of measures taken during the Chester step test to predict aerobic power and to prescribe aerobic exercise

OBJECTIVES: To evaluate the reliability and validity of measures taken during the Chester step test (CST) used to predict VO(2)max and prescribe subsequent exercise. METHODS: The CST was performed twice on separate days by 7 males and 6 females aged 22.4 (SD 4.6) years. Heart rate (HR), ratings of perceived exertion (RPE), and oxygen uptake (VO(2)) were measured at each stage of the CST. RESULTS: RPE, HR, and actual VO(2) were the same at each stage for both trials but each of these measures was significantly different between CST stages (p<0.0005). Intertrial bias +/-95% limits of agreement (95% LoA) of HR reached acceptable limits at CST stage IV (-2+/-10 beats/min) and for RPE at stages III (0.2+/-1.4) and IV (0.5+/-1.9). Age estimated HRmax significantly overestimated actual HRmax of 5 beats/min (p = 0.016) and the 95% LoA showed that this error could range from an underestimation of 17 beats/min to an overestimation of 7 beats/min. Estimated versus actual VO(2) at each CST stage during both trials showed errors ranging between 11% and 19%. Trial 1 underestimated actual VO(2)max by 2.8 ml/kg/min (p = 0.006) and trial 2 by 1.6 ml/kg/min (not significant). The intertrial agreement in predicted VO(2)max was relatively narrow with a bias +/-95% LoA of -0.8+/-3.7 ml/kg/min. The RPE and %HRmax (actual) correlation improved with a second trial. At all CST stages in trial 2 RPE:%HRmax coefficients were significant with the highest correlations at CST stages III (r = 0.78) and IV (r = 0.84). CONCLUSION: CST VO(2)max prediction validity is questioned but the CST is reliable on a test-retest basis. VO(2)max prediction error is due more to VO(2) estimation error at each CST stage compared with error in age estimated HRmax. The HR/RPE relation at >50% VO(2)max reliably represents the recommended intensity for developing cardiorespiratory fitness, but only when a practice trial of the CST is first performed.     

Is determination of exercise intensities as percentages of VO2max or HRmax adequate?

Often exercise intensities are defined as percentages of maximal oxygen uptake (VO2max) or heart rate (HRmax). PURPOSE: The purpose of this investigation was to test the applicability of these criteria in comparison with the individual anaerobic threshold. METHODS: One progressive cycling test to exhaustion (initial stage 100 W, increment 50 W every 3 min) was analyzed in a group of 36 male cyclists and triathletes (24.9 +/- 5.5 yr; 71.6 +/- 5.7 kg; VO2max: 62.2 +/- 5.0 mL x min(-1) x kg(-1); individual anaerobic threshold = IAT: 3.64 +/- 0.41 W x kg(-1); HRmax: 188 +/- 8 min). Power output and lactate concentrations for 60 and 75% of VO2max as well as for 70 and 85% of HRmax were related to the IAT. RESULTS: There was no significant difference between the mean value of IAT (261 +/- 34 W, 2.92 +/- 0.65 mmol x L(-1)), 75% of VO2max (257 +/- 24 W, 2.84 +/-0.92 mmol x L(-1)), and 85% of HRmax (259 +/- 30 W, 2.98 +/- 0.87 mmol L(-1)). However, the percentages of the IAT ranged between 86 and 118% for 75% VO2max and 87 and 116% for 85% HRmax (corresponding lactate concentrations: 1.41-4.57 mmol x L(-1) and 1.25-4.93 mmol x L(-1), respectively). The mean values at 60% of VO2max (198 +/- 19 W, 1.55 +/- 0.67 mmol x L(-1)) and 70% of HRmax (180 +/- 27 W, 1.45 +/- 0.57 mmol x L(-1)) differed significantly (P < 0.0001) from the IAT and represented a wide range of intensities (66-91% and 53-85% of the IAT, 0.70-3.16 and 0.70-2.91 mmol x L(-1), respectively). CONCLUSIONS: In a moderately to highly endurance-trained group, the percentages of VO2max and HRmax vary considerably in relation to the IAT. As most physiological responses to exercise are intensity dependent, reliance on these parameters alone without considering the IAT is not sufficient.     

A longitudinal assessment of change in VO2max and maximal heart rate in master athletes

PURPOSE: The purpose of this study was to determine the longitudinal change in VO2max and HRmax in male and female master endurance runners and to compare these changes based upon gender, age, and change in training volume. METHODS: Eighty-six male (53.9 +/- 1.1 yr) and 49 female (49.1 +/- 1.2 yr) master endurance runners were tested an average of 8.5 yr apart. Subjects were grouped by age at first visit, change in VO2max, and change in training volume. Measurements included body composition by hydrostatic weighing, maximal exercise testing on a treadmill, and training history by questionnaire. Data were analyzed by ANOVA and multiple regression. RESULTS: VO2max and HRmax declined significantly regardless of gender or age group (P < 0.05). The rate of change in VO2max by age group ranged from -1% to -4.6% per year for men and -0.5% to 2.4% per year for women. Men with the greatest loss in VO2max had the greatest loss in LBM (-2.8 +/- 0.7 kg), whereas women with the greatest loss in VO2max demonstrated the greatest change in training volume (-24.1 +/- 3.0 km.wk-1). Additionally, women with the greatest loss in VO2max (-9.6 +/- 2.6 mL.kg-1.min-1) did not replace estrogen after menopause independent of age. HRmax change did not differ by VO2max change or training volume change in either gender. CONCLUSIONS: In conclusion, these data suggest that VO2max declines in male and female master athletes at a rate similar to or greater than that expected in sedentary older adults. Additionally, these data suggest that maintenance of LBM and VO2max were associated in men, whereas in women, estrogen replacement and maintenance of training volume were associated with maintained VO2max.     

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.     

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

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

Absolute and relative work capacity in women at 758, 586, and 523 torr barometric pressure

Six young women performed an incremental bicycle work test at sea level barometric pressure (PB = 758 torr) and during acute exposure (1 h) to simulated altitudes of PB 586 and 523 torr. Submaximal oxygen uptake (VO2) for a given workload was independent of altitude but maximal oxygen uptake (VO2 max) decreased 10 and 13%, respectively, at the higher altitudes. Although heart rate (fC) was consistently higher at altitude for a given VO2, the slope of fC vs, VO2 was independent of altitude and VO2 max. Exercise fC appeared to be a function of the relative workload i.e. VO2 as a percentage of VO2 max measured at each PB. Carbon dioxide (CO2) elimination increased with altitude for a given VO2 but also was a function of the relative workload. Pulmonary ventilation (BTPS), however, was consistently 10-15% higher at altitude when expressed as a percent of VO2 max, primarily due to an increase in respiratory rate. Compared to published studies on males, this increased ventilation may impart a slight advantage to women in maintaining arterial oxygenation, but ventilatory reserve may be decreased and limited at higher altitudes. At altitudes down to PB 523 torr, the control of fC responses and decrements in maximal oxygen uptake in women were similar to males, but ventilatory control mechanisms differed.     

Acute hypoxia decreases cardiac response to catecholamines in exercising humans

Cardiac chronotropic response to adrenergic activity at rest and exercise has been studied in 8 sea-level natives on the first two days of exposure to high altitude hypoxia (3823 m, 473 mmHg). Maximal O2 uptake (VO2max) was determined at low altitude (day 0:D0) and high altitude (day 2:D2). Submaximal exercise tests were performed at low altitude (day 1:D1) and high altitude (days 3 and 4: D3, D4). Plasma venous norepinephrine (NE) and epinephrine (E) concentrations were determined at rest and at the end of submaximal exercise. From D0 to D2, maximal heart rate decreased by 7% (p less than 0.01), and VO2max decreased by 17% (p less than 0.01). During submaximal exercise, plasma NE did not vary significantly (D1: 1.36 +/- 0.57, D3: 1.48 +/- 0.51, D4: 1.31 +/- 0.54 ng.ml-1). In contrast, relative work load decreased at high altitude (% VO2max at D1, D3 and D4 were respectively: 90.2 +/- 6.1, 83.3 +/- 9.8, 76.9 +/- 8.2). Linear relationships were found, both at low and high altitudes, between NE and VO2, NE and % VO2max, and between the increases in NE and heart rate during exercise. Covariance analysis indicates that these relations shifted to the left at high altitude:for the same NE or increase in NE, VO2 or increase in heart rate was lower at high altitude. Variations in E were similar but not significant. We conclude that hypoxia induced a decrease in cardiac chronotropic response to adrenergic activation during submaximal exercise.     

Evidence and possible mechanisms of altered maximum heart rate with endurance training and tapering

Exercise physiologists, coaches and athletes have traditionally used heart rate (HR) to monitor training intensity during exercise. While it is known that aerobic training decreases submaximal HR (HRsubmax) at a given absolute exercise workload, the general consensus is that maximum HR (HRmax) is relatively unaltered regardless of training status in a given population. It has not been seriously postulated as to whether HRmax can change modestly with aerobic training/detraining. Despite several sources stating that HRmax is unaltered with training, several studies report that HRmax is reduced following regular aerobic exercise by sedentary adults and endurance athletes, and can increase upon cessation of aerobic exercise. Furthermore, evidence suggests that tapering/detraining can increase HRmax. Therefore, it is plausible that some of the same mechanisms that affect both resting and HRsubmax may also play a role in altered HRmax. Some of the proposed mechanisms for changes in HRmax that may occur with aerobic training include autonomic (extrinsic) factors such as plasma volume expansion and(enhanced baroreflex function, while some nonautonomic (intrinsic) factors are alteration of the electrophysiology of the sinoatrial (SA) node and decreased beta-adrenergic receptor number and density. There is a high correlation between changes in both maximal oxygen uptake (VO2 max) and HRmax that occurs with training, tapering and detraining (r= -0.76: p < 0.0001; n = 314), which indicates that as VO2max improves with training, HRmax tends to decrease, and when detraining ensues, HRmax tends to increase. The overall effect of aerobic training and detraining on HRmax is moderate: effect sizes based on several studies were calculated to be -0.48 and +0.54, respectively. Therefore, analysis reveals that HRmax can be altered by 3 to 7% with aerobic training/detraining. However, because of a lack of research in the area of training on HRmax, the reader should remain speculative and allow for cautious interpretation until further, more thorough investigations are carried out as to the confirmation of mechanisms involved. Despite the limitations of using HR and HRmax as a guide to training intensity, the practical implications of monitoring changing HRmax are: (i) prescribed training intensities may be more precisely monitored; and (ii) prevention of overtraining may possibly be enhanced. As such, it may be sensible to monitor HRmax directly in athletes throughout the training year, perhaps at every macrocycle (3 to 6 weeks).     

Influence of acute moderate hypoxia on time to exhaustion at vVO2max in unacclimatized runners

Eight unacclimatized long-distance runners performed, on a level treadmill, an incremental test to determine the maximal oxygen uptake (VO2max) and the minimal velocity eliciting VO2max (vVO2max) in normoxia (N) and acute moderate hypoxia (H) corresponding to an altitude of 2,400 m (PIO 2 of 109 mmHg). Afterwards, on separate days, they performed two all-out constant velocity runs at vO2 max in a random order (one in N and the other in H). The decrease in VO2max between N and H showed a great degree of variability amongst subjects as VO2max decreased by 8.9 +/- 4 ml x min(-1) x kg)(-1) in H vs. N conditions (-15.3 +/- 6.3 % with a range from -7.9 % to -23.8 %). This decrease in VO2max was proportional to the value of VO2max (VO2max vs. delta VO2max N-H, r = 0.75, p = 0.03). The time run at vVO2max was not affected by hypoxia (483 +/- 122 vs. 506 +/- 148 s, in N and H, respectively, p = 0.37). However, the greater the decrease in vVO2max during hypoxia, the greater the runners increased their time to exhaustion at vVO2max (vVO2max N-H vs. tlim @vVO2max N-H, r = -0.75, p = 0.03). In conclusion, this study showed that there was a positive association between the extent of decrease in vVO2max, and the increase in run time at vVO2max in hypoxia.     

Training high--living low: changes of aerobic performance and muscle structure with training at simulated altitude.

This study was undertaken to test the hypothesis that endurance training in hypoxia is superior to training of the same intensity in normoxia. To avoid adaptation to hypoxia, the subjects lived under normoxic conditions when not training. A secondary objective of this study was to compare the effect of high- vs. moderate-intensity training on aerobic performance variables. Thirty-three men without prior endurance training underwent a cycle ergometer training of 6 weeks, 5 d/week, 30 minutes/d. The subjects were assigned to 4 groups, N-high, N-low, H-high and H-low based on the training criteria normoxia (N; corresponding to a training altitude of 600 m), vs. hypoxia (H; training altitude 3850 m) and intensity (high; corresponding to 80% and low: corresponding to 67% of VO2max). VO2max measured in normoxia increased between 8.5 to 11.1%, independent of training altitude or intensity. VO2max measured in hypoxia increased between 2.9 and 7.2%. Hypoxia training resulted in significantly larger increases than normoxia training. Maximal power that subjects could maintain over a thirty-minute period (measured in normoxia or hypoxia) increased from 12.3 - 26.8% independent of training altitude. However, subjects training at high intensity increased performance more than subjects training at a low intensity. Muscle volume of the knee-extensors as measured by magnetic resonance imaging increased significantly in the H-high group only (+ 5.0%). Mitochondrial volume density measured by EM-morphometry in biopsy samples of m. vastus lat. increased significantly in all groups with the highest increase seen in the H-high group (+ 59%). Capillary length density increased significantly in the H-high group only (+ 17.2%). The main finding of this study is that in previously untrained people, training in hypoxia while living at low altitude increases performance in normoxia to the same extent as training in normoxia, but leads to larger increases of aerobic performance variables when measured under hypoxic conditions. Training intensity had no effect on the gain of VO2max. On the level of skeletal muscle tissue, the combination of hypoxia with high training intensity constitutes the most effective stimulus for increasing muscle oxidative capacity.     

Maximal metabolic responses of deep and shallow water running in trained runners

The purpose of this study was to compare the maximal metabolic responses of competitive runners during treadmill running (TMR), deep water running (DWR), and shallow water running (SWR). Seven male and two female members of the Wheaton College varsity cross country team served as subjects. Maximal measures included oxygen consumption (VO2max), respiratory exchange ratio (RER), heart rate (HRmax), and lactic acid (HLA). Repeated-measures ANOVA revealed treadmill running to elicit higher VO2max and HRmax than both water tests (P less than 0.05). VO2max was also greater for SWR than for DWR (P less than 0.05). VO2max values for SWR and DWR were 90.3% and 73.5% of TMR, respectively. HRmax for SWR and DWR were 88.6% and 86% of TMR, respectively. RER and HLA did not differ among tests. These data suggest that shallow water running is capable of eliciting metabolic responses comparable to treadmill running. Shallow water running elicits higher metabolic responses than deep water running.     

The influence of fitness and body weight on preferred exercise intensity

PURPOSE: The purpose of this investigation was to determine the individual and combined effects of aerobic fitness and body weight on physiological responses, perceived exertion, and speed variables during self-selected steady-state treadmill (TM) walking in 60 healthy college-age women. METHODS: The women were placed into one of four categories based on body mass index (BMI) and fitness level, assessed by a graded TM test. Subjects walked continuously on a TM at a self-selected pace for 15 min at a 2.5% grade. The dependent variables were oxygen uptake (VO(2)), HR, percentage of maximal oxygen uptake (VO(2max)), percentage of HRmax (%HRmax), RPE for the overall body, TM belt speed, and total energy expenditure (EE). RESULTS: There were no significant interactions or body weight main effects for any of the dependent variables. However, lower-fitness subjects walked at a TM speed that resulted in a higher (P < 0.0005) VO(2max) (52.4 vs 39.56) than the higher-fitness subjects. CONCLUSION: These findings suggest that fitness, and not body weight, influences preferred exercise intensity as measured by VO(2max) during TM walking in college-age women. The self-selected walking speed did not result in an intensity, as determined by VO(2max), that is consistent with the enhancement of cardiorespiratory fitness for higher-fitness women regardless of body weight.     

The effect of training on exercise-induced R-wave amplitude changes in young females

The effects of an exercise training program on R-wave amplitude (Ramp) changes during graded exercise were investigated in 14 adolescent females. The experimental group (EG) (N = 6) underwent a 20-wk aerobic exercise program. Eight subjects served as controls (CG). Oxygen uptake (VO2), heart rate (HR), and Ramp were determined during incremental exercise to exhaustion, pre- and post-program. The Ramp was calculated by using the average of 10 electrocardiographic complexes to provide a stable criterion. Pre-training, EG and CG were not significantly different for VO2max and HRmax; Ramp decreased significantly between rest and 5 min prior to exhaustion for both groups (P less than 0.05). Ramp changes were significant between the first min of exercise and 2 min prior to exhaustion for EG (P less than 0.05) and between the first min of exercise and 1 min prior to exhaustion for CG (P less than 0.05). These changes occurred at 87% of VO2max and 95% of HRmax for EG and at 93% of VO2max and 97% of HRmax for CG. CG showed no change in these variables post-program except for Ramp exhibiting a significant change between rest and the first min of exercise (P less than 0.05). EG showed a significant increase in VO2max (P less than 0.05), and Ramp changes during exercise were delayed. The first significant change occurred between rest and 3 min prior to exhaustion (P less than 0.05), and the second change occurred between the first min of exercise and exhaustion (P less than 0.05). Thus the latter Ramp change was delayed to 100% of VO2max and HRmax post-training.(ABSTRACT TRUNCATED AT 250 WORDS)     

The effect of altitude on cycling performance: a challenge to traditional concepts.

Acute exposure to moderate altitude is likely to enhance cycling performance on flat terrain because the benefit of reduced aerodynamic drag outweighs the decrease in maximum aerobic power [maximal oxygen uptake (VO2max)]. In contrast, when the course is mountainous, cycling performance will be reduced at moderate altitude. Living and training at altitude, or living in an hypoxic environment (approximately 2500 m) but training near sea level, are popular practices among elite cyclists seeking enhanced performance at sea level. In an attempt to confirm or refute the efficacy of these practices, we reviewed studies conducted on highly-trained athletes and, where possible, on elite cyclists. To ensure relevance of the information to the conditions likely to be encountered by cyclists, we concentrated our literature survey on studies that have used 2- to 4-week exposures to moderate altitude (1500 to 3000 m). With acclimatisation there is strong evidence of decreased production or increased clearance of lactate in the muscle, moderate evidence of enhanced muscle buffering capacity (beta m) and tenuous evidence of improved mechanical efficiency (ME) of cycling. Our analysis of the relevant literature indicates that, in contrast to the existing paradigm, adaptation to natural or simulated moderate altitude does not stimulate red cell production sufficiently to increase red cell volume (RCV) and haemoglobin mass (Hb(mass)). Hypoxia does increase serum erthyropoietin levels but the next step in the erythropoietic cascade is not clearly established; there is only weak evidence of an increase in young red blood cells (reticulocytes). Moreover, the collective evidence from studies of highly-trained athletes indicates that adaptation to hypoxia is unlikely to enhance sea level VO2max. Such enhancement would be expected if RCV and Hb(mass) were elevated. The accumulated results of 5 different research groups that have used controlled study designs indicate that continuous living and training at moderate altitude does not improve sea level performance of high level athletes. However, recent studies from 3 independent laboratories have consistently shown small improvements after living in hypoxia and training near sea level. While other research groups have attributed the improved performance to increased RCV and VO2max, we cite evidence that changes at the muscle level (beta m and ME) could be the fundamental mechanism. While living at altitude but training near sea level may be optimal for enhancing the performance of competitive cyclists, much further research is required to confirm its benefit. If this benefit does exist, it probably varies between individuals and averages little more than 1%.     

Long-term intermittent hypoxia increases O2-transport capacity but not VO2max

Long-term intermittent hypoxia, characterized by several days or weeks at altitude with periodic stays at sea level, is a frequently occurring pattern of life in mountainous countries demanding a good state of physical performance. The aim of the study was to determine the effects of a typical South American type of long-term intermittent hypoxia on VO2max at altitude and at sea level. We therefore compared an intermittently exposed group of soldiers (IH) who regularly (6 months) performed hypoxic-normoxic cycles of 11 days at 3550 m and 3 days at sea level with a group of soldiers from sea level (SL, control group) at 0 m and in acute hypoxia at 3550 m. VO2max was determined in both groups 1 day after arrival at altitude and at sea level. At altitude, the decrease in VO2max was less pronounced in IH (10.6 +/- 4.2%) than in SL (14.1 +/- 4.7%). However, no significant differences in VO2max were found between the groups either at sea level or at altitude, although arterial oxygen content (Ca(O(2) )) at maximum exercise was elevated (p < 0.001) in IH compared to SL by 11.7% at sea level and by 8.9% at altitude. This higher Ca(O(2) ) mainly resulted from augmented hemoglobin mass (IH: 836 +/- 103 g, SL: 751 +/- 72 g, p < 0.05) and at altitude also from increased arterial O(2)-saturation. In conclusion, acclimatization to long-term intermittent hypoxia substantially increases Ca(O(2) ), but has no beneficial effects on physical performance either at altitude or at sea level.     

吸烟人群戒烟后运动心肺功能变化跟踪研究

目的跟踪监测长期吸烟者戒烟后运动心肺功能变化情况,探讨戒烟对机体的心肺功能的改善作用。方法应用运动心肺检查负荷递增方案,跟踪监测12名长期吸烟者在戒烟后运动心肺功能的变化情况,记录并比较其戒烟前、戒烟后6、12、18、24个月时心肺功能核心指标变化情况。结果戒烟后原吸烟者最大心率、最大耗氧量、无氧阈、最大二氧化碳排出量、最大每分通气量等主要心肺功能指标均有改善,戒烟12个月以后改善显著,18个月之后上述指标较12个月继续改善,至观察期结束各项指标保持稳定。结论吸烟者戒烟后心肺功能逐渐改善,机体心肺功能储备得到部分恢复,运动能力提高。     

Measurement of maximal oxygen uptake from two different laboratory protocols in runners and squash players.

PURPOSE: The aims of the study were to assess whether different test protocols used to elicit maximal oxygen uptake values (VO2max) attain similar results, whether different VO2max protocols were preferable for different athletic groups, and to assess whether the noninvasive criteria used to indicate the attainment of VO2max are achieved similarly in different VO2max testing protocols. METHODS: This study evaluated the attainment of either VO2max or peak VO2 (VO2peak) during two treadmill VO2max protocols: a progressive speed protocol (PSP) and a progressive incline protocol (PIP). Ten runners and 10 squash players were studied to assess whether achievement of VO2max criteria was either sport-specific or protocol-specific, or both. RESULTS: There were no significant differences in the VO2peak values reached in either PSP or PIP protocol (64.4 +/- 5.9 vs 66.5 +/- 6.0 mLO2 x kg(-1) x min(-1)). But HRmax (196 +/- 5 vs 189 +/- 5 beats x min(-1); PSP vs PIP; P < 0.01) and RER (1.14 +/- 0.05 vs 1.07 +/- 0.04; PSP vs PIP; P < 0.01) were significantly higher during the PSP test. Fifty percent of the subjects reached a plateau in either test, and of these subjects, 90% satisfied the three noninvasive criteria for VO2max in the PSP group, compared with 10% in the PIP group. CONCLUSIONS: The indirect criteria used to assess the attainment of VO2max may be limited, as the VO2peak values were higher in the PIP protocol compared with the PSP protocol, although not significantly different, whereas the HR and RER values were significantly lower in the PIP than PSP protocol. Furthermore, only 50% of subjects demonstrated the plateau phenomenon in oxygen uptake with either protocol. It may be concluded that the measured physiological variables coinciding with VO2peak may differ when different protocols are used to elicit VO2max.