Estimation of VO2max from a one-mile track walk, gender, age, and body weight

The purpose of this investigation was to explore an alternative field test to estimate maximal oxygen consumption (VO2max) using a one-mile walk test. VO2max was determined in 343 healthy adult (males = 165, females = 178) subjects 30 to 69 yr using a treadmill protocol (mean +/- SD: VO2max = 37.0 +/- 10.7 ml X kg-1 X min-1). Each subject performed a minimum of two, one-mile track walks as fast as possible. The two fastest walks (T1, T2) with elapsed times within 30 s were used for subsequent analyses. Heart rates were monitored continuously and recorded every one-quarter mile. Multiple regression analysis (best sub-sets) to estimate VO2max (l X min-1) yielded the following predictor variables: track walk-1 time (T1); fourth quarter heart rate for track walk-1 (HR 1-4); age (yr); weight (lb); and sex (1 = male, 0 = female). The best equation (N = 174) was: VO2max = 6.9652 + (0.0091*WT) - (0.0257*AGE) + (0.5955*SEX) - (0.2240*T1) - (0.0115*HR1-4); r = 0.93, SEE = 0.325 l X min-1. Comparing observed and estimated VO2max values in a cross-validation group (N = 169) resulted in r = 0.92, SEE = 0.355 l X min-1. Generalized and sex-specific equations to estimate VO2max (ml X kg-1 X min-1) were also generated. The accuracy of estimation as expressed by SEE was similar among the equations. The results indicate that this one-mile walk test protocol provides a valid sub-maximum assessment for VO2max estimation.     

Accurate prediction of VO2max in cycle ergometry

Numerous equations exist for predicting VO2max from the duration (an analog of maximal work rate, Wmax) of a treadmill graded exercise test (GXT). Since a similar equation for cycle ergometry (CE) was not available, we saw the need to develop such an equation, hypothesizing that CE VO2max could be accurately predicted due to its more direct relationship with W. Thus, healthy, sedentary males (N = 115) and females (N = 116), aged 20-70 yr, were given a 15 W.min-1 CE GXT. The following multiple linear regression equations which predict VO2max (ml.min-1) from the independent variables of Wmax (W), body weight (kg), and age (yr) were derived from our subjects: Males: Y = 10.51 (W) + 6.35 (kg) - 10.49 (yr) + 519.3 ml.min-1; R = 0.939, SEE = 212 ml.min-1. Females: Y = 9.39 (W) + 7.7 (kg) - 5.88 (yr) + 136.7 ml.min-1; R = 0.932, SEE = 147 ml.min-1 Using the 95% confidence limits as examples of worst case errors, our equations predict VO2max to within 10% of its true value. Internal (double cross-validation) and external cross-validation analyses yielded r values ranging between 0.920 and 0.950 for the male and female regression equations. These results indicate that use of the equations generated in this study for a 15 W.min-1 CE GXT provides accurate estimates of VO2max.     

The reliability and validity of the Astrand nomogram and linear extrapolation for deriving VO2max from submaximal exercise data

BACKGROUND: While the accepted measure of aerobic power remains the VO2max this test is extremely demanding even for athletes. There are serious practical and ethical concerns in attempting such testing in non-athletic or patient populations. An alternative method of measuring aerobic power in such populations is required. A limited body of work exists evaluating the accuracy of the Astrand-Ryhming nomogram and linear extrapolation of the heart rate/oxygen uptake plot. Issues exist in terms of both equipment employed and sample numbers. METHODS: Twenty-five normal subjects (mean age 28.6, range 22-50) completed 52 trials (Bruce treadmill protocol) meeting stringent criteria for VO2max performance. Respiratory gases were measured with a portable gas analyser on a five-sec sample period. The data was analysed to allow comparison of the reliability and validity of linear extrapolations to three estimates of heart rate maximum with the Astrand nomogram prediction. RESULTS: Extrapolation was preferable yielding intraclass correlation co-efficients (ICC) of 0.9433 comparable to that of the observed VO2max at 0.9443 and a bias of -1.1 ml x min(-1) x kg(-1) representing a 2.19 percent underestimate. CONCLUSIONS: This study provides empirical evidence that extrapolation of submaximal data can be employed with confidence for both clinical monitoring and research purposes. With the use of portable equipment and submaximal testing the scope for future research in numerous populations and non-laboratory environments is considerably increased.     

Prediction of functional aerobic capacity without exercise testing

The purpose of this study was to develop functional aerobic capacity prediction models without using exercise tests (N-Ex) and to compare the accuracy with Astrand single-stage submaximal prediction methods. The data of 2,009 subjects (9.7% female) were randomly divided into validation (N = 1,543) and cross-validation (N = 466) samples. The validation sample was used to develop two N-Ex models to estimate VO2peak. Gender, age, body composition, and self-report activity were used to develop two N-Ex prediction models. One model estimated percent fat from skinfolds (N-Ex %fat) and the other used body mass index (N-Ex BMI) to represent body composition. The multiple correlations for the developed models were R = 0.81 (SE = 5.3 ml.kg-1.min-1) and R = 0.78 (SE = 5.6 ml.kg-1.min-1). This accuracy was confirmed when applied to the cross-validation sample. The N-Ex models were more accurate than what was obtained from VO2peak estimated from the Astrand prediction models. The SEs of the Astrand models ranged from 5.5-9.7 ml.kg-1.min-1. The N-Ex models were cross-validated on 59 men on hypertensive medication and 71 men who were found to have a positive exercise ECG. The SEs of the N-Ex models ranged from 4.6-5.4 ml.kg-1.min-1 with these subjects.(ABSTRACT TRUNCATED AT 250 WORDS)     

A new nonexercise-based VO2(max) equation for aerobically trained females

PURPOSE: The purposes of the present study were to (a) modify previously published VO2(max) equations using the constant error (CE) values for aerobically trained females, (b) cross-validate the modified equations to determine their accuracy for estimating VO2(max) in aerobically trained females, (c) derive a new nonexercise-based equation for estimating VO2(max) in aerobically trained females if the modified equations are found to be inaccurate, and (d) cross-validate the new VO2(max) equation using the PRESS statistic and an independent sample of aerobically trained females. METHODS: A total of 115 aerobically trained females (mean +/- SD: age = 38.5 +/- 9.4 yr) performed a maximal incremental test on a cycle ergometer to determine actual VO2(max). The predicted VO2(max) values from nine published equations were compared with actual VO2(max) by examining the CE, standard error of estimate (SEE), validity coefficient (r), and total error (TE). RESULTS: Cross-validation of the modified nonexercise-based equations on a random subsample of 50 subjects resulted in a %TE > or = 13% of the mean of actual VO2(max). Therefore, the following nonexercise-based VO2(max) equation was derived on a random subsample of 80 subjects: VO2(max) (mL x min(-1)) = 18.528 (weight in kg) + 11.993 (height in cm) - 17.197(age in yr) + 23.522 (h x wk(-1) of training) + 62.118 (intensity of training using the Borg 6-20) + 278.262 (natural log of years of training) - 1375.878 (R = 0.83, R2 adjusted = 0.67, and SEE = 259 mL x min(-1)). Cross-validation of this equation on the remaining sample of 35 subjects resulted in a %TE of 10%. CONCLUSIONS: The nonexercise equation presented here is recommended over previously published equations for estimating VO2(max) in aerobically trained females.     

Marathon performance in relation to maximal aerobic power and training indices in female distance runners.

The purpose of this study was to examine the relationships of marathon performance time (MPT) to maximal aerobic power (VO2 max), physical characteristics, and training indices recorded for 12 weeks prior to a race in 35 female distance runners. The marathon experience of the subjects ranged from two to fifteen races. Physical and aerobic power characteristics (mean +/- S.D.) were: age, 35.7 +/- 8.5 yr; height, 166.4 +/- 5.7 cm; weight, 55.1 +/- 5.7 kg; body fat, 15.7 +/- 5.0%; VO2 max, 56.5 +/- 6.2 ml . kg-1 . min-1. Marathon time for this race averaged 227.0 +/- 31.6 min. Records from individual training diaries indicated the runners averaged 71.0 +/- 10.0 workout days, 10.0 +/- 10.0 two X day-1 workouts, 81.0 +/- 8.0 total workouts, 12.3 +/- 1.8 mean km . workout-1, 5402.8 +/- 1302.6 total training min, 187.0 +/- 18.0 m . min-1 training pace, 112.2 +/- 32.1 max km . wk-1, 83.1 +/- 23.4 mean km . wk-1, 998.8 +/- 282.6 km . 12 wk-1 and 13.8 +/- 2.4 mean km . day-1. MPT was positively correlated to body mass index (r = 0.52), and body fat (r = 0.52) but negatively related to VO2 max (r = -0.65). MPT was also negatively related to previous marathons completed (r = -0.47), workout days (r = -0.47), two X day-1 workouts (r = -0.52), total workouts (r = -0.56), mean km . workout-1 (r = -0.58), total training min (r = -0.56), m . min-1, training pace (r = -0.66), max km . wk-1 (r = -0.70), mean km . wk-1 (r = -0.74), km . 12 wk-1 (r = -0.74), and mean km . day-1 (r = -0.77). MPT for our population of runners may be predicted (r = 0.82, R2 = 0.68) by the following equation: MPT, (min) = 449.88 - 7.61 (-/x km.day-1 run) - 0.63 (m.min-1, training pace); SEE = +/- 18.4 min.     

Validity of VO2max equations for aerobically trained males and females

PURPOSE: The purpose of this investigation was to cross-validate existing VO2max prediction equations on samples of aerobically trained males and females. METHODS: A total of 142 aerobically trained males (mean +/- SD; 39.0 +/- 11.1 yr, N = 93) and females (39.7 +/- 10.1 yr, N = 49) performed a maximal incremental test to determine actual VO2max on a cycle ergometer. The predicted VO2max values from 18 equations (nine for each gender) were compared with actual VO2max by examining the constant error (CE), standard error of estimate (SEE), correlation coefficient (r), and total error (TE). RESULTS: The results of this investigation indicated that all of the equations resulted in significant (P < 0.006) CE values ranging from -216 to 1415 mL x min(-1) for the males and 132 to 1037 mL x min(-1) for the females. In addition the SEE, r, and TE values ranged from 266 to 609 mL x min(-1), 0.36 to 0.88, and 317 to 1535 mL x min(-1), respectively. Furthermore, the lowest TE values for the males and females represented 10% and 12% of the mean actual VO2max values, respectively. CONCLUSIONS: The results of the analysis indicated that the two equations using age, body weight, and the power output achieved at VO2 as predictor variables had the lowest SEE (7.7-9.8% of actual VO2max) and TE (10-12% of actual VO2max) values and are recommended for estimating VO2max in aerobically trained males and females. The magnitude of the TE values (>or= 20% of actual VO2max) associated with the remaining 16 equations, however, were too large to be of practical value for estimating VO2max.     

Development of a single-stage submaximal treadmill walking test

An equation was developed to estimate maximal oxygen uptake (VO2max, ml.kg-1.min-1) based on a single submaximal stage of a treadmill walking test. Subjects (67 males, 72 females) aged 20-59 yr completed 4-min stages at 0, 5, and 10% grades walking at a constant speed (2.0-4.5 mph) and then performed a VO2max test. Heart rate and respiratory gas exchange variables were measured during the test. Multiple regression analysis (N = 117) to estimate VO2max from the 4-min stage at 5% grade yielded the following model (R2 = 0.86; SEE = 4.85 ml.kg-1.min-1): VO2max = 15.1 + 21.8*SPEED (mph) -0.327*HEART RATE (bpm) -0.263*SPEED*AGE (yr) + 0.00504*HEART RATE*AGE + 5.98*GENDER (0 = Female; 1 = Male). The constant and all coefficients were highly significant (P less than 0.01). To assess the accuracy of the model in a cross-validation group (N = 22), an estimated VO2max value was obtained using the above model. Estimated VO2max then was regressed on observed VO2max yielding the following equation (R2 = 0.92): ESTIMATED VO2max = 0.15 + 1.03*OBSERVED VO2max. The intercept and slope of this equation were not significantly different from 0 and 1, respectively. For 90.9% of the subjects in the cross-validation group, residual scores were within the range of +/- 5 ml.kg-1.min-1. In conclusion, this submaximal walking test based on a single stage of a treadmill protocol provides a valid and time-efficient method for estimating VO2max.     

Accelerometry and heart rate as a measure of physical fitness: proof of concept

PURPOSE: This study focused on developing a new method to assess VO2max outside laboratory conditions and without the need for maximal exertion. We hypothesized that the combined use of accelerometry and HR monitoring, under daily life conditions, could provide a good estimate of physical fitness. METHODS: Twenty-six healthy subjects (15 women, 11 men), aged 28 +/- 7 yr, performed a maximal incremental test on a bicycle ergometer to determine VO2max. Body composition was measured with underwater weighing and deuterium dilution using a three-compartment model. A triaxial accelerometer (Tracmor) and an HR monitor were worn for seven consecutive days under free-living conditions. The ratio of HR to activity counts per minute (ACM) was used as a fitness index (HR.ACM(-1)). RESULTS: As hypothesized, HR.ACM(-1) was significantly correlated with VO2max. Using fat-free mass (FFM) (P < 0.0001), age (P = 0.025), and HR.ACM(-1) (P = 0.021) as the independent variables, the explained variation in VO2max was 76% (P < 0.0001, SEE = 363 mL x min(-1)). In order to generate a prediction formula that is applicable in the field when no data on body composition are available, the same analysis was done with body mass and gender in the model instead of FFM. HR.ACM(-1) was significantly (P = 0.023) correlated with VO2max. The total explained variation of the model was 71%, with a SEE of 409 mL x min(-1), or 13.7% of the average VO2max. CONCLUSION: After correction for body composition, VO2max was significantly related to HR.ACM(-1). It is, to our knowledge, the first tool that yields a measure of VO2max by monitoring people in their daily life activities without the need for a specific protocol or for maximal exertion, and therefore is applicable to a large variety of subjects.     

Cardiorespiratory fitness in relation to self-reported physical function in cancer patients after chemotherapy

AIM: The aim of this study was to estimate the association between objective cardiorespiratory fitness (CRF) and subjective self-reported physical function, taking into account the influence of mental distress. We hypothesized an association between these parameters, since they might be thought to measure parts of the same phenomenon. METHODS: Approximately 1 month after discontinuation of all primary treatment, 90 cancer patients aged 18-50 years treated with chemotherapy were surveyed. CRF was determined by the Astrand-Ryhming indirect cycle ergometer test, which indicate peak VO2 in mL x kg(-1) x min(-1) (predicted VO2max). Self-reported physical function was assessed by The European Organisation for Research and Treatment of Cancer Core Quality of Life Questionnaire (EORTC QLQ-C30). The relation between VO2max and self-reported physical function was estimated by multiple linear regression. Mental distress (assessed by The Hospital Anxiety and Depression scale), age, gender, body mass index (BMI), time from treatment to physical test and diagnoses were included as potential confounders. RESULTS: There was no association between predicted VO2max and self-reported physical function. Mental distress was negatively associated with self-reported physical function (P<0.001), but is not associated with predicted VO2max. CONCLUSIONS: The results suggest that predicted VO2max does not reflect self-reported physical function and vice versa in cancer patients after chemotherapy. If information about cardiac and/or pulmonary status is required, direct or indirect measures of VO2max should be used.     

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.     

Overuse and distorsion soccer injuries related to the player's estimated maximal aerobic work capacity

Fourty senior male soccer players were selected for this study. Before the season, each subject performed an exercise test, and the maximal capacity of oxygen uptake was estimated according to Astrand and Rhyming. The exercise test was repeated in 25 subjects 6 months later. The subjects were then ranked according to their estimated maximal capacity of oxygen uptake (estimated VO2 max) at the first test and allocated into one of three groups of similar size. During the season, all new injuries were examined and registered by an orthopaedic surgeon, and the subjects were allocated into one of three groups (overuse injuries, distorsion injuries, and other injuries). There were significantly more overuse injuries among subjects with high estimated VO2 max, and the incidence of distorsion injuries tended to be lower among subjects with high estimated VO2 max. No correlation was found regarding the total incidence of injuries and estimated VO2 max. No significant difference in estimated VO2 max was registered between the tests before and after the season.     

Pulmonary ventilation in relation to oxygen uptake and carbon dioxide production during incremental load work

The purposes of the present investigation were: (1) to describe the relationships between exercise pulmonary ventilation (VE) and oxygen uptake (VO2) and VE and carbon dioxide production (VCO2), (2) to determine the % VO2 max at the lowest ventilatory equivalent of oxygen (VEO2), and (3) to examine the relationship between the % VO2 max at the lowest VEO2 and maximal aerobic power (VO2 max). During incremental load work, VE increased exponentially in relation to elevations in VO2 and VCO2. Differentiation of the VE to VO2 exponential equation gives the minimum slope of the equation and corresponds to the lowest ventilatory equivalent for oxygen. In our subjects, VO2 max (mean +/- SD) was 3.84 +/- 0.71 l . min-1, and VO2 at the lowest VEO2 was 1.70 +/- 0.32 l . min-1. The VO2 at the lowest VEO2 was 44.3 +/- 4.0% VO2 max (range 37% to 53% VO2 max). The correlation coefficient (r) between VO2 at the lowest VEO2 and VO2 max was 0.90, while the r between % VO2 max at the lowest VEO2 and VO2 max was -0.24.     

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.     

Running economy of elite male and elite female runners.

Twenty female and 45 male middle and long-distance runners, in training for the U.S. Olympic Trials, served as subjects. Ninety percent of both men and women subjects reached the Trials; eight women and 12 men qualified for the Olympic Games and five won medals. Each subject completed a VO2max and a series of submax treadmill runs, for the purpose of comparing heart rate (HR), VO2, and blood lactate (HLa) among men and women and among runners of various event specialties. Results showed the men to be taller, heavier, to have a lower six-site skinfold sum and a higher VO2max, than the women (P less than 0.05); there was no difference in age. When compared in running economy, men used less oxygen (ml.min-1.kg-1) at common absolute velocities, but VO2 (ml.km-1.kg-1) was not different between men and women at equal relative intensities (%VO2max). When men and women of equal VO2max were compared, the men were significantly more economical, using any method of comparison. Also, when comparisons of men and women of equal economy were made, it was found that the men had an even greater advantage over the "matched" women subjects than the mean VO2max comparison using all subjects. In looking at the SD (800-/1500-m runners), MD (3-K/5-K/10-K runners) and LD (marathon runners), it was found that the SD runners used the least oxygen (ml.min-1.kg-1) at speeds of marathon race pace and faster, but not at slower speeds. Men and women responded similarly in this regard. Running economy data for speeds slower than typical race paces, tended to show the LD runners to be most economical, suggesting that the speeds over which runners are tested plays an important part in determining which subjects are the most economical. It was concluded that at absolute running velocities, men are more economical than women, but when expressed in ml.km-1.kg-1 there are no gender differences at similar relative intensities of running. Also, when men and women of equal VO2max or equal economy are matched, the men show a better aerobic profile. It is recommended that economy data be collected up to speeds equal to over 90% VO2max.     

Measuring and predicting maximal aerobic power in international-level intermittent sport athletes

AIM: The purpose of this study was to measure actual VO2max during the multi-stage fitness test (MSFT) and to compare this with predicted values obtained using previously established, commonly used methods. We also wanted to determine a new and more accurate regression equation for the prediction of VO2max in intermittent sport athletes. METHODS: Twenty-six, elite, male, intermittent sport athletes performed the MSFT with oxygen uptake (VO2) and heart rate (HR) measured throughout. Paired t-tests were used to compare measured VO2max with predicted VO2max. Linear regression was used to determine the equation for the prediction of VO2max from the total number of shuttles completed. RESULTS: There were no differences between the two methods of predicting VO2max, however, both predicted values (53.6+/-3.9 and 51.3+/-4 mL x kg(-1) x min(-1)) were significantly lower (9.3% and 13.2%, respectively) than measured VO2max (59.1+/-6.6 mL x kg(-1) x min(-1), P < 0.001). Correlations between measured and predicted VO2max were similar for both prediction methods (r = 0.61, P = 0.013 and r = 0.68 and P = 0.004). We present a new prediction equation [Y (VO2max, mL x kg(-1) x min(-1)) = 0.38 x total number of shuttles completed +25.98] (where R = 0.69; R2 = 0.48; SEE = 4.9 mL x kg(-1) x min(-1); SEE% = 8.3) which provides a more valid method of predicting actual max in intermittent sport athletes. CONCLUSIONS: A new regression equation to predict VO2max in intermittent sport athletes has been established. Whilst some error in predicting VO2max still exists, the new equation will provide coaches and sport-scientists with a more suitable equation with which to predict VO2max in intermittent sport athletes.     

Cardiovascular fitness and thermoregulation during prolonged exercise in man.

Nine healthy male subjects differing in their training status (VO2 max 54 +/- 7 ml.min-1.kg-1, mean +/- SD; 43-64 ml.min-1 kg-1, range) exercised on two occasions separated by one week. On each occasion, having fasted overnight, subjects exercised for 1 h on an electrically braked cycle ergometer at a workload equivalent to 70 per cent VO2 max (test A) or at a fixed workload of 140 W (test B). Each test was assigned in a randomized manner and was performed at an ambient temperature of 22.5 +/- 0.0 degrees C and a relative humidity of 85 +/- 0 per cent. Absolute exercise workload was the most successful predictor of sweat loss during test A (r = 0.82, p less than 0.01). Sweat loss was also related to VO2 max tests A (r = 0.67, p less than 0.05) and B (r = 0.67, p less than 0.05). There was no relationship between resting pre-exercise core temperature and VO2 max. However, core temperature recorded during the final min of exercise in test B was inversely related to VO2 max (r = -0.86, p less than 0.01). As a consequence, core temperature during the final minute of exercise was also related to the relative exercise intensity (% VO2 max) performed (r = 0.82, p less than 0.01). The heart rate response during test B was inversely related to VO2 max (r = -0.71, p less than 0.05) and was positively related to the relative exercise intensity performed (r = 0.68, p less than 0.05). No relationship was found between weighted mean skin temperature during the final minute of exercise and the relative (r = 0.26) or absolute (r = 0.03) workloads performed during exercise. The results of the present experiment suggest that cardiovascular fitness (as indicated by VO2 max) will have a significant influence upon the thermoregulatory responses of Man during exercise.     

Exercise training below and above the lactate threshold in the elderly

In this study we report the effects of training at intensities below and above the lactate threshold on parameters of aerobic function in elderly subjects (age range 65-75 yr). The subjects were randomized into high-intensity (HI, N = 8; 75% of heart rate reserve = approximately 82% VO2max = approximately 121% of lactate threshold) and low-intensity (LI, N = 9; 35% of heart rate reserve = approximately 53% VO2max = approximately 72% of lactate threshold) training groups which trained 4 d.wk-1 for 30 min.session-1 for 8 wk. Before and after the training, subjects performed an incremental exercise test for determination of maximal aerobic power (VO2max) and lactate threshold (LT). In addition, the subjects performed a 6-min single-stage exercise test at greater than 75% of pre-training VO2max (SST-High) during which cardiorespiratory responses were evaluated each minute of the test. After training, the improvements in VO2max (7%) for LI and HI were not different from one another (delta VO2max for LI = 1.8 +/- 0.7 ml.kg-1.min-1; delta VO2max for HI = 1.8 +/- 1.0 ml.kg-1.min-1) but were significantly greater (P = 0.02) than the post-testing change observed in the control group (N = 8). Training improved the LT significantly (10-12%; P less than 0.01) and equally for both LI and HI (delta LT for for LI = 2.3 +/- 0.6 ml O2.kg-1.min-1; delta LT for HI = 1.8 +/- 0.8 ml O2.kg-1.min-1).(ABSTRACT TRUNCATED AT 250 WORDS)     

Relationship of heart rate to oxygen uptake during weight lifting exercise

To define the relation of heart rate to oxygen uptake during weight lifting (WL), heart rate (HR) and oxygen uptake (VO2) were determined during bouts of WL at four intensities (40, 50, 60, and 70% of one-repetition maximum (1-RM)) in 15 males. The 11.5-min bouts of WL consisted of three circuits using four exercises (bench press, bent-over row, arm curl, and parallel squat), with each performed for ten repetitions over a 30-s period with a 1:1 work/rest ratio. During lifting at the four intensities, mean (+/- SE) VO2 values were 1.31 +/- 0.04, 1.50 +/- 0.07, 1.72 +/- 0.07, and 1.86 +/- 0.08 l.min-1, or 33-47% of treadmill-determined VO2max. Mean (+/- SE) HR values were 124 +/- 4, 134 +/- 4, 148 +/- 5, and 161 +/- 4 beats.min-1, or 63-82% of maximal HR. The slope of the linear regression equation predicting %VO2max from %HRmax (Y = 0.582X - 1.7911, r = 0.86, SEE = 3.4%) was approximately half that reported for dynamic low-resistance exercise such as running or cycling. At a given %HRmax, %VO2max was consistently lower than predicted for dynamic low-resistance exercise. It was concluded that the HR/VO2 relationship during dynamic high-resistance exercise for intensities between 40 and 70% of 1-RM is linear but is different from that reported for dynamic low-resistance exercise. The data are consistent with the conclusion in previous studies that using HR to prescribe the metabolic intensity of WL exercise results in a substantially lower level of aerobic metabolism than during dynamic low-resistance exercise.     

Parasympathetic control of resting heart rate: relationship to aerobic power

The degree of parasympathetic control of resting heart rate (PC) was assessed by measurement of variation in heart period (VHP) during cardiopulmonary synchronization of respiration. Respiratory period was arbitrarily preset and standardized at 7 heart beats (3 beats inspiration, 4 beats expiration). The mathematical and experimental evidence for this technique is elucidated. Twenty-one healthy subjects were examined for the relationship of aerobic power (VO2max) to (1) VHP and (2) respiratory sinus arrhythmia (RSA) waveform amplitude and phase. Intraindividual variability in VHP was low (test-retest r = 0.97-0.98). VHP in msec was a logarithmic function of VO2max (ml X kg FFW-1 X min-1) according to the equation: 1n VHP = 0.27 + 0.082 X VO2max where r = 0.92, P less than 0.001). VHP was more closely related to VO2max than was resting HR (r = -0.75). In addition, a higher VO2max was associated with a leftward shift of the HR: respiratory cycle sinusoidal curve. These results illustrate the close relationship between aerobic power and vagal tone in control of resting heart rate. Individuals with a higher aerobic power maintain lower resting heart rates mainly via an increase in parasympathetic tone (as opposed to a decreased sympathetic tone). Previous correlations between RSA characteristics and age may be accounted for by age-related decreases in VO2max.