American College Of Sports Medicine Equation Research Articles

Estimating metabolic rate from ISO heart rate method and two walking equations.

Assigning a value for metabolic rate is central to heat stress assessment. ISO 8996 describes a predictive method for walking based on the American College of Sports Medicine (ACSM) method and another generalized method based on average heart rate. In addition, the US Army uses the load carriage decision aid (LCDA) predictive equation to estimate metabolic rate. The purpose of this study was to assess the accuracy/bias and precision of the ISO heart rate method and the ACSM and LCDA equations. The laboratory database included metabolic rate, heart rate, treadmill speed, and grade during a progressive heat stress protocol. Treadmill speed and grade were set to represent one of three metabolic rates. Accuracy and precision were assessed with Bland-Altman plots. All three methods had good accuracy (low bias). For precision, the ISO heart rate method had a root mean square error (RMSE) of 34 W and 11% when adjusted for repeated measures. The RMSE for two equations was 20 W and 7%. Although the heart method had less accuracy, its application is more generalizable. The heart rate method should be used below the occupational exposure limit for heat stress to avoid a bias toward higher predicted values due to heat strain.

Cardiorespiratory Fitness’ Indirect Assessment With Running Metabolic Equations Among Healthy Active Men

VO2max is defined as the highest amount of oxygen the cardiovascular and pulmonary systems can supply and the highest amount of oxygen the muscular system can use during intense physical exertion. It is widely accepted as the criterion measure of cardiorespiratory fitness. Unfortunately, accessibility to VO2max’s direct measurement is restricted. Therefore, several metabolic equations have been developed to estimate VO2max using indirect calculation. The most commonly used equations are those developed by the American College of Sports Medicine (ACSM) and recently, the research group of Fitness Registry and the Importance of Exercise National Database developed a new metabolic equation (FRIEND). PURPOSE: The aim of this study is to evaluate the accuracy of the ACSM and FRIEND equations to estimate VO2max comparatively to direct O2 consumption measurement in healthy active men. METHODS: 54 healthy active men aged between 19-60y.o. (36,6±5,4)(BMI: 24,1±2,6kg/m2) performed a maximal treadmill test using a metabolic cart (Vyntus CPX) to measure direct VO2max (mL O2/kg*min-1). VO2max estimation was then calculated using ACSM and FRIEND running metabolic equations. For analysis, they were separated in two age groups (18-34 vs 35-60y.o.) to evaluate if it has an impact on the metabolic equations used. Results were compared using a two-way ANOVA. RESULTS: When compared to the direct measurement (53,9±7,2 (18-34y.o.) and 49,8±4,4 (35-60y.o.)), both ACSM and FRIEND equations showed significantly higher results in both age group (mean overestimation: 12,7; p<0,001 and 3,7; p=0,005, respectively). However, the FRIEND equation was significantly lower than the ACSM equation (mean difference: 9,0; p<0,001). Moreover, ACSM showed a very large effect size (Hedge’s g=1,84) while FRIEND showed a medium effect size (Hedge’s g=0,58). As for the two age groups, results varied similarly using the two equations (p=0,781). CONCLUSIONS: The VO2max calculated with the metabolic equations for running showed overestimated values in our male sample. The average difference between direct and indirect measurement when using the FRIEND equation suggests a better accuracy. More research is needed to evaluate the accuracy in different populations and different fitness levels to optimize the VO2 estimation formula.

Validation of FRIEND and ACSM Equations for Cardiorespiratory Fitness: Comparison to Direct Measurement in CAD Patients.

The regression equation of the American College of Sports Medicine (ACSM) was a preferred method for estimating maximal oxygen consumption (VO2max). Recently, a more precise equation from the fitness registry and the importance of exercise national database (FRIEND) for healthy people was developed. This study compared VO2max estimated by the ACSM and FRIEND equations to VO2max directly measured in coronary artery disease (CAD) patients. Overall, 293 CAD patients who participated in cardiac rehabilitation between June 2015 and December 2018 were analyzed. Directly measured VO2max values were compared to the ACSM and FRIEND equations. The directly measured VO2max was significantly different from the estimated VO2max by ACSM equation (24.16 vs. 28.7 mL/kg/min, p < 0.001), which was overestimated by 20% in men and 16% in women. However, there was no statistically significant difference between the directly measured VO2max and the estimated VO2max by the FRIEND equation. (24.16 vs. 24.15 mL/kg/min, p = 0.986). In CAD patients, the estimated VO2max from the ACSM equation was significantly higher than the directly measured VO2max. In addition, estimated cardiorespiratory fitness (CRF) by the FRIEND equation showed similar results with directly measured CRF. As a result, the FRIEND equation can predict CRF more accurately than the ACSM.

Predicting the rate of oxygen consumption during the 3-minute constant-rate stair stepping and shuttle tests in people with COPD

BackgroundThe 3-minute constant-rate stair stepping (3-min CRSST) and constant-speed shuttle tests (3-min CSST) were developed to assess breathlessness in response to a standardized exercise stimulus. Estimating the rate of oxygen consumption (V’O2) during these tests would assist clinicians to relate the stepping/shuttle speeds that elicit breathlessness to daily physical activities with a similar metabolic demand. This study: (I) developed equations to estimate the V’O2 of these tests in people with chronic obstructive pulmonary disease (COPD); and (II) compared the newly developed and American College of Sports Medicine (ACSM) metabolic equations for estimating the V’O2 of these tests.MethodsThis study was a retrospective analysis of people with COPD who completed a 3-min CRSST (n=98) or 3-min CSST (n=69). Multivariate linear regression estimated predictors (alpha <0.05) of V’O2 to construct COPD-specific metabolic equations. The mean squared error (MSE) of the COPD-specific and ACSM equations was calculated and compared. Bland-Altman analyses evaluated level of agreement between measured and predicted V’O2 using each equation; limits of agreement (LoA) and patterns of bias were compared.ResultsStepping rate/shuttle speed and body mass were identified as significant predictors of V’O2. The MSE of the COPD-specific equations was 0.05 L·min−1 for both tests. Mean difference between measured and predicted V’O2 was 0.00 L·min−1 (95% LoA −0.46, 0.46) and 0.00 L·min−1 (95% LoA −0.44, 0.44) for the 3-min CRSST and 3-min CSST, respectively. For the ACSM metabolic equations, the MSE was 0.10 L·min−1 and 0.18 L·min−1 for the 3-min CRSST and 3-min CSST, respectively. The ACSM metabolic equations underestimated V’O2 of the 3-min CRSST by −0.18 L·min−1 (95% LoA −0.68, 0.32), and overestimated V’O2 of the 3-min CSST by 0.35 L·min−1 (95% LoA −0.14, 0.84).ConclusionsThis study presents metabolic equations to predict V’O2 of the 3-min CRSST and 3-min CSST for people with COPD that are more accurate than the ACSM metabolic equations.

P2501Validation of FRIEND and ACSM equations for cardiorespiratory fitness: comparison to direct measurement in male CAD patients

Abstract Introduction Cardiorespiratory fitness (CRF) is associated with a high risk of cardiovascular disease and all-cause mortality. The regression equation of American College of Sports Medicine (ACSM) was a preferred method for estimating maximal oxygen consumption (VO2max). It is well-known that CRF is overestimated in ACSM equation. Recently, Kokkinos reported more precise equation from the Fitness Registry and the Importance of Exercise National Database (FRIEND). Both equations were made from western healthy people. Purpose In this study, we compared VO2max estimated by ACSM and FRIEND equations to VO2max directly measured in male coronary artery disease (CAD) patients. Methods We analyzed 103 male CAD patients who underwent percutaneous coronary intervention and who participated in cardiac rehabilitation between June 2015 and December 2018. VO2max was directly measured by the gas exchange analysis during treadmill test with modified Bruce protocol. Exclusive criteria were pulmonary disease, chronic kidney disease on hemodialysis, malignancy, peripheral artery disease, insufficient cardiopulmonary exercise test and orthopedic injuries. Directly measured VO2max were compared to ACSM and FRIEND equations. Results Age-specific VO2max values, which were directly measured from male CAD patients, were shown in Table. Smaller CRF difference was shown in FRIEND equation than ACSM equation. Compared to the measured value, CRF estimated by ACSM equation was overestimated by 22%, but the one estimated by FRIEND equation had only 2% gap. Figure presents Bland-Altman plots. ACSM equation had the higher bias (5.52ml/kg/min) compared with FRIEND equation (0.200ml/kg/min). Comparison table of VO2max estimated by ACSM and FRIEND equations with directly measured VO2max in male CAD patients Age Number VO2max (ml/kg/min) Measured ACSM % predicted FRIEND % predicted 30–39 4 29.5 ± (6.6) 35.7 ± (6.1) 122.3 ± (8.5) 29.1 ± (4.3) 100.1 ± (8.7) 40–49 20 29.1 ± (5.1) 35.7 ± (5.4) 123.6 ± (11.1) 29.1 ± (3.8) 101.2 ± (9.5) 50–59 32 25.6 ± (4.3) 31.5 ± (5.1) 123.8 ± (10.1) 26.2 ± (3.6) 103.2 ± (8.5) 60–69 27 26.0 ± (5.1) 31.1 ± (2.6) 120.5 ± (12.6) 25.9 ± (4.0) 100.8 ± (10.5) 70–79 18 21.2 ± (6.0) 26.8 ± (5.4) 123.2 ± (14.8) 22.8 ± (3.9) 105.2 ± (12.0) &gt;80 2 25.0 ± (10.1) 22.8 ± (2.6) 97 ± (28.9) 19.9 ± (1.9) 85.1 ± (27.0) Total 103 25.7 ± (5.6) 31.4 ± (6.0) 122.2 ± (12.4) 26.1 ± (4.3) 102.1 ± (10.4) Data are presented as mean ± (standard deviation). Bland-Altman plots Conclusions FRIEND equation can estimate CRF more accurately than ACSM equation, even in Asian patients with CAD.

Validation of New Skinfold Prediction Equation Based on Dual-Energy X-Ray Absorptiometry for Women

There is a high demand for affordable body composition assessments of body fat and fat free mass. Research has demonstrated that skinfold prediction equations recommended by the American College of Sports Medicine (ACSM) underestimate body fat percentage (%BF). PURPOSE: The purpose of this study was to validate an alternative equation for women created from dual energy x-ray absorptiometry (DXA). The DXA criterion (DC) equation is: %BF= -6.40665 + 0.491946(S3SF) - 0.00126(S3SF)2 + 0.12515(hip) + 0.06437(age); (S3SF = sum of triceps, suprailiac, thigh; hip = circumference in cm; age = years). METHODS: Anthropometrics (skinfolds and circumferences) and a DXA scan were completed on 78 women (mean ± SD) [age: 28.0 ± 10.1 yr., height: 165.1 ± 5.9 cm, mass: 63.5 ± 10.5 kg., BMI: 23.2 ± 3.2 kg/m2]. The three Jackson-Pollock skinfold prediction equations (JP7, JP3a, and JP3b) and the DC equation were compared to DXA %BF. RESULTS: Two-way ANOVA with repeated measures detected significant differences (p < 0.05) in the %BF with post hoc-comparisons revealing significant differences among JP7 (21.4 ± 5.8), JP3a (22.3 ± 5.9), and JP3b (22.7 ± 5.7) as compared to the DXA (26.6 ± 5.4). No significant difference existed between DC %BF (26.6 ± 5.9) and DXA %BF (26.6 ± 5.4) (p = 1.0) and the two assessments were highly correlated (R = 0.87). The standard error of the measurement for the DC equation was low (2.98%). CONCLUSION: The DC equation more accurately predicted %BF across a general population of women than the recommended ACSM equations. Practitioners should consider its use and exercise caution when using older equations since they may yield lower %BF compared to DXA.

New Generalized Equation for Predicting Maximal Oxygen Uptake (from the Fitness Registry and the Importance of Exercise National Database)

Impaired cardiorespiratory fitness (CRF) is closely linked to chronic illness and associated with adverse events. The American College of Sports Medicine (ACSM) regression equations (ACSM equations) developed to estimate oxygen uptake have known limitations leading to well-documented overestimation of CRF, especially at higher work rates. Thus, there is a need to explore alternative equations to more accurately predict CRF. We assessed maximal oxygen uptake (VO2 max) obtained directly by open-circuit spirometry in 7,983 apparently healthy subjects who participated in the Fitness Registry and the Importance of Exercise National Database (FRIEND). We randomly sampled 70% of the participants from each of the following age categories: <40, 40 to 50, 50 to 70, and ≥70 and used the remaining 30% for validation. Multivariable linear regression analysis was applied to identify the most relevant variables and construct the best prediction model for VO2 max. Treadmill speed and treadmill speed× grade were considered in the final model as predictors of measured VO2 max and the following equation was generated: VO2 max in ml O2/kg/min= speed (m/min)× (0.17+ fractional grade× 0.79)+ 3.5. The FRIEND equation predicted VO2 max with an overall error >4 times lower than the error associated with the traditional ACSM equations (5.1 ± 18.3% vs 21.4 ± 24.9%, respectively). Overestimation associated with the ACSM equation was accentuated when different protocols were considered separately. In conclusion, The FRIEND equation predicts VO2 max more precisely than the traditional ACSM equations with an overall error >4 times lower than that associated with the ACSM equations.

Pedaling rate is an important determinant of human oxygen uptake during exercise on the cycle ergometer.

Estimation of human oxygen uptake () during exercise is often used as an alternative when its direct measurement is not feasible. The American College of Sports Medicine (ACSM) suggests estimating human during exercise on a cycle ergometer through an equation that considers individual's body mass and external work rate, but not pedaling rate (PR). We hypothesized that including PR in the ACSM equation would improve its prediction accuracy. Ten healthy male participants’ (age 19–48 years) were recruited and their steady-state was recorded on a cycle ergometer for 16 combinations of external work rates (0, 50, 100, and 150 W) and PR (50, 70, 90, and 110 revolutions per minute). was calculated by means of a new equation, and by the ACSM equation for comparison. Kinematic data were collected by means of an infrared 3-D motion analysis system in order to explore the mechanical determinants of . Including PR in the ACSM equation improved the accuracy for prediction of sub-maximal during exercise (mean bias 1.9 vs. 3.3 mL O2 kg−1 min−1) but it did not affect the accuracy for prediction of maximal (P > 0.05). Confirming the validity of this new equation, the results were replicated for data reported in the literature in 51 participants. We conclude that PR is an important determinant of human during cycling exercise, and it should be considered when predicting oxygen consumption.

Consumo de oxigênio de pico em idosas: comparação entre valores medidos e previstos

O objetivo deste estudo foi comparar o consumo de oxigênio de pico (VO2pico) mensurado por meio de teste de esforço e os obtidos por equações preditivas. Participaram deste estudo 116 idosas (66,7 ± 5,8 anos), que realizaram teste ergoespirométrico em esteira. Os valores de VO2pico também foram estimados pela equação do Colégio Americano de Medicina do Esporte (ACSM) e equação de Foster. As comparações foram realizadas por meio da ANOVA para medidas repetidas. A relação entre valores da esteira e equações foi examinada pelo coeficiente de Pearson e método de Bland e Altman. As equações do ACSM e Foster superestimaram significantemente o VO2pico medido (p&lt;0,001; diferença média de 6,9 e 2,7 ml.kg-1.min-1, respectivamente), sendo que a equação ACSM gerou valores superiores aos de Foster (p&lt;0,05). Houve correlação positiva entre o valor do teste e o das equações (r=0,70; p&lt;0,01), mas uma correlação negativa entre idade e VO2pico (r=-0,31; p=0,001). Os achados demonstram que para idosas, equações ergométricas comumente usadas superestimam o VO2pico em relação aos mensurados pela ergoespirometria, apontando para cautela quando da classificação da aptidão cardiorrespiratória por testes ergométricos.

Estimation of peak oxygen uptake from peak power output in able-bodied and paraplegic individuals

This study assessed the accuracy of predicting peak oxygen uptake (V˙O2peak) from peak power output (POpeak) using the equation described by the American College of Sports Medicine (ACSM) during arm-cranking exercise in able-bodied and paraplegic individuals. A total of 13 able-bodied (age: 27.2 ± 4.3 years; mass: 74.5 ± 11.8 kg) and 13 paraplegic men (age: 31.6 ± 5.8 years; mass: 63.7 ± 11.1 kg) volunteered to take part in this study. Participants completed a ramp exercise test (started at 0 W and increased by 15 W/minute) and a graded exercise test (GXT, started at 30 W and increased by 15 W every 2 minutes) designed to assess whether V˙O2peak, POpeak, and peak heart rate (HRpeak) differed between the two exercise tests. POpeak was significantly higher for the ramp exercise test compared with GXT (p < 0.05). For GXT, no significant difference was noted in the two groups between measured and predicted V˙O2peak from POpeak using the ACSM equation. The 95% limits of agreement between measured and predicted V˙O2peak was quite narrow for paraplegic persons (1 ± 6) but not for able-bodied individuals (1 ± 10). In the same way, there was a stronger relationship between measured and predicted V˙O2peak for paraplegic persons [intraclass correlation coefficients (ICC) = 0.92] compared with able-bodied participants (ICC = 0.77). For the ramp exercise test, predicted V˙O2peak was significantly higher (p < 0.01) than measured V˙O2peak for both groups. In conclusion, V˙O2peak can be predicted with reasonable accuracy from POpeak obtained in GXT using the ACSM equation during arm-cranking exercise in able-bodied and paraplegic individuals.

Validação das equações metabólicas para caminhada e corrida propostas pelo American College of Sports Medicine em homens entre 20 e 30 anos de idade

O American College of Sports Medicine (ACSM) sugere equações para estimativa do gasto metabólico da caminhada e da corrida, concebidas a partir de pressupostos: 1) que o indivíduo esteja executando uma atividade em estado de equilíbrio e 2) que o consumo de oxigênio (VO2) tem relação linear com a intensidade do trabalho. O objetivo deste estudo foi verificar a validade concorrente dessas equações metabólicas em homens regularmente ativos entre 20 e 30 anos de idade, tendo como medida critério a espirometria (TEEM-100, AeroSport). Participaram deste estudo 36 homens jovens e ativos. No primeiro dia, os voluntários executaram um teste máximo de exercício na esteira (ATL 10200, Inbrasport). Os indivíduos completaram um trabalho padronizado de 30 minutos com seis diferentes estágios de caminhada e corrida (80,4; 120,6 e 160,8m.min-1) com (5%) e sem inclinação, 48 a 96h após o teste máximo. Além da estatística descritiva, utilizaram-se a correlação linear de Pearson, o coeficiente de determinação, a ANOVA com um fator e o teste t pareado, com o nível de significância estabelecido em 0,05. Todos os procedimentos foram realizados no pacote estatístico SPSS. Os resultados apontaram para a superestimação do VO2 em ambas as atividades (p &lt; 0,05), sobretudo na corrida, com exceção para 80,4 e 120,6m.min-1, sem inclinação (diferença média de -30 a 20% para caminhada e de 3,2 a 12% para corrida). Os valores de erro padrão de estimativa (EPE) variaram entre 1,56 e 3,15ml O2.kg-1.min-1 e em torno de 3,5ml O2.kg-1.min-1, para caminhada e corrida, respectivamente. A correlação foi maior que 0,7 para todos os estágios. Contudo, seguindo os critérios estabelecidos por Lohman (1992), as equações não foram validadas. Dessa forma, em homens ativos, o EPE deverá ser considerado, pois as equações metabólicas propostas pelo ACSM superestimam os valores de VO2.

How Accurately are Maximal Metabolic Equivalents Estimated Based on the Treadmill Workload in Healthy People and Asymptomatic Subjects with Cardiovascular Risk Factors?

Maximal exercise capacity expressed as metabolic equivalents (METs) is rarely directly measured (measured METs; mMETs) but estimated from maximal workload (estimated METs; eMETs). We assessed the accuracy of predicting mMETs by eMETs in asymptomatic subjects. Thirty-four healthy volunteers without cardiovascular risk factors (controls) and 90 patients with at least one risk factor underwent cardiopulmonary exercise testing using individualized treadmill ramp protocols. The equation of the American College of Sports Medicine (ACSM) was employed to calculate eMETs. Despite a close correlation between eMETs and mMETs (patients: r = 0.82, controls: r = 0.88; p < 0.001 for both), eMETs were higher than mMETs in both patients [11.7 (8.9 - 13.4) vs. 8.2 (7.0 - 10.6) METs; p < 0.001] and controls [17.0 (16.2 - 18.2) vs. 15.6 (14.2 - 17.0) METs; p < 0.001]. The absolute [2.5 (1.6 - 3.7) vs. 1.3 (0.9 - 2.1) METs; p < 0.001] and the relative [28 (19 - 47) vs. 9 (6 - 14) %; p < 0.001] difference between eMETs and mMETs was higher in patients. In patients, ratio limits of agreement of 1.33 (*/ divided by 1.40) between eMETs and mMETs were obtained, whereas the ratio limits of agreement were 1.09 (*/ divided by 1.13) in controls. The ACSM equation is associated with a significant overestimation of mMETs in young and fit subjects, which is markedly more pronounced in older and less fit subjects with cardiovascular risk factors.

INFLUENCE OF HIGHER-GRADE WALKING ON METABOLIC DEMANDS IN YOUNG UNTRAINED JAPANESE WOMEN

The primary purpose of this study was to document the physiological responses of level walking and running (LW/R) at various speeds, and grade walking (GW) at various grades on a treadmill. Twenty-four young untrained Japanese women performed 2 tests on the specially designed treadmill for a higher grade exercise. The first test was the LW/R with increase of speeds, 33.3, 66.7, 91.7, and 116.7 m·min-1. The first 3 progressions were for walking and the last progression was for running. The second test was the GW with increase of grades 0, 10, 20, and 30% with the velocity of 33.3 m·min-1 in all progressions. The different combinations of speeds and grade for the progressions used in this study were selected based on the results of preliminary pilot studies, so that the percent heart rate maximim (%HRmax) was reached at the minimum intensities recommended to allow improving cardiorespiratory fitness by the American College of Sports Medicine (ACSM). Significant (p ≤ 0.05) differences were found for O2 (l·min-1 and l·kg-1·min-1), HR, %HRmax, percent heart rate reserve, and rating of perceived exertion between all 4 progressions in LW/R and GW. However, no significant differences in all variables except step rate between each progression for LW/R and GW. There were significant differences between measured O2 and O2 calculated from ACSM metabolic equations on all progressions in LW/R and GW (p ≤ 0.05). These results indicated that the walking at the slower speed of 33.3 m·min-1 at a higher grade of 30% is effective as much as the level running at 116.6 m·min-1, and more effective than brisk level walking at 91.7 m·min-1 to improve cardiorespiratory fitness in untrained young women. The ACSM equation for walking and running underestimates O2 for young untrained Japanese women. Population characteristics (e.g., body size and age) should be considered when designing cardiorespiratory fitness programs based on the ACSM equation.

Influence of Higher-Grade Walking on Metabolic Demands in Young Untrained Japanese Women

The primary purpose of this study was to document the physiological responses of level walking and running (LW/R) at various speeds, and grade walking (GW) at various grades on a treadmill. Twenty-four young untrained Japanese women performed 2 tests on the specially designed treadmill for a higher grade exercise. The first test was the LW/R with increase of speeds, 33.3, 66.7, 91.7, and 116.7 m.min(-1). The first 3 progressions were for walking and the last progression was for running. The second test was the GW with increase of grades 0, 10, 20, and 30% with the velocity of 33.3 m.min(-1) in all progressions. The different combinations of speeds and grade for the progressions used in this study were selected based on the results of preliminary pilot studies, so that the percent heart rate maximim (%HRmax) was reached at the minimum intensities recommended to allow improving cardiorespiratory fitness by the American College of Sports Medicine (ACSM). Significant (p <or= 0.05) differences were found for VO2 (l.min(-1) and l.kg(-1).min(-1)), HR, %HRmax, percent heart rate reserve, and rating of perceived exertion between all 4 progressions in LW/R and GW. However, no significant differences in all variables except step rate between each progression for LW/R and GW. There were significant differences between measured VO2 and VO2 calculated from ACSM metabolic equations on all progressions in LW/R and GW (p <or= 0.05). These results indicated that the walking at the slower speed of 33.3 m.min(-1) at a higher grade of 30% is effective as much as the level running at 116.6 m.min(-1), and more effective than brisk level walking at 91.7 m.min(-1) to improve cardiorespiratory fitness in untrained young women. The ACSM equation for walking and running underestimates VO2 for young untrained Japanese women. Population characteristics (e.g., body size and age) should be considered when designing cardiorespiratory fitness programs based on the ACSM equation.

Energy cost calculations for exercise prescription: an update.

Recent research has resulted in a number of recommended changes in how fitness professionals should prescribe target workloads and calculate the energy cost of exercise. The principal changes are in the use of oxygen consumption reserve (VO2R) as an alternative to percentage of maximal oxygen consumption (VO2max) for prescribing exercise intensity, the use of net VO2 rather than gross VO2 for the calculation of caloric expenditure during exercise, and a modification of the American College of Sports Medicine (ACSM) equation for calculating the oxygen cost of leg cycle ergometry. The VO2R method of prescribing exercise workloads is similar to the heart rate reserve (HRR) method of prescribing target heart rates, i.e. the target workload is established at a given percentage of the difference between maximal and resting VO2. Several recent studies have shown that there is a discrepancy between the exercise intensity at given percentages of HRR and VO2max, but that HRR and VO2R yield equivalent exercise intensities. The use of VO2R in exercise prescription provides more accurate target workloads, especially for individuals with a low fitness level. Net VO2 during exercise is that amount above resting VO2 due to the exercise itself. A recent recommendation is to employ net VO2 in the calculation of the caloric expenditure during exercise, so as not to overestimate potential bodyweight loss. Several recent studies of leg cycling ergometry have yielded equations for the estimation of VO2 that include a term for unloaded cycling, i.e. the oxygen cost of moving the legs against zero resistance. The equations from these studies provide more accurate estimations of cycling VO2 than the existing ACSM equation, and a new standardised equation has been developed and adopted by the ACSM. The new equation is especially useful for improving the accuracy of VO2 estimates during low intensity leg cycle ergometry. The ACSM equation for bench stepping has also been modified to include a term for resting metabolism.

Validation of a cycle ergometry equation for predicting steady-rate ??VO2

The purpose of this study was to validate an equation used for predicting the oxygen cost of leg cycle ergometry. This equation was previously shown to be more accurate than the one of the American College of Sports Medicine (ACSM) and appears as: VO2 (ml.min-1) = kgm.min-1 x 1.9 ml.min-1 + ((3.5 ml.kg-1.min-1 x kg body weight) + 260 ml.min-1). Fifty healthy males, ages 18-38 yr old, performed a six-stage (0, 180, 360, 540, 720, and 900 kgm.min-1) submaximal cycle ergometry test while their oxygen uptake was measured. Results indicated the standard error of estimate for the predicted oxygen consumption values ranged from 80-156 ml.min-1, with correlations between the actual and predicted values ranging from r = 0.35 to r = 0.67. Total errors ranged from 92-160 ml.min-1. All of the standard errors and total errors were lower and all of the correlations, except one, were higher at each power load in the validation sample than the original sample. These statistics support the generalizability and accuracy of the new equation. It would appear that the new equation may make accurate predictions in independent samples and is more precise than the ACSM equation.

Physiologic Responses of Patients With Cardiac Disease to Arm, Leg, and Combined Arm and Leg Work on an Air-Braked Ergometer

Cardiorespiratory responses to three modes of air-braked ergometry were compared in nine stable patients with cardiac disease ( ± standard deviation [SD]: age, 63.7 ± 6.2 years of age; height, 172.2 ± 4.0 cm; weight, 75.8 ± 14.4 kg). Exercise modes included arm ergometry (AE), leg ergometry (LE), and combined arm and leg ergometry (ALE). A discontinuous protocol was selected with 3 minutes of exercise and 1 minute of recovery. Work loads were increased 0.5 kiloponds (kp) per stage. Tests were conducted to volitional fatigue. A two-way repeated analysis of variance (ANOVA) was used to determine significance between the exercise modes. Actual vs American College of Sports Medicine (ACSM) predicted oxygen uptake (VO2) values were evaluated by ANOVA to determine accuracy of predicted values. Heart rate (P < 0.05), minute ventilation (VE) (P < 0.001) ventiatory equivalents for oxygen (O2) (P < 0.001) and carbon dioxide (CO2) (P <0.05), and calculated myocardial oxygen uptake (MVO2) were significantly higher (P < 0.05) for AE than either LE or ALE at work loads of 1.0, 1.5, and 2.0 kp. Oxygen uptake (P < 0.05) and CO2 production (VCO2) (P < 0.01) were significantly elevated during AE, and this reflected a significantly elevated respiratory exchange ratio (RER) (P < 0.001). Mechanical efficiency (ME) was lower during AE compared with LE or ALE. Average maximal work loads for AE were 57% lower than for either LE or ALE. This was associated with a 14% lower value for VE, 18% lower value for VO2, 25% lower value for calculated metabolic equivalents (METS), and a 27% lower value for ME. For all exercise modes, actual VO2 values were compared with the ACSM predicted VO2 values The ACSM equation for AE significantly overpredicted VO2 at 1.5 to 2.5 kp work loads. The LE equation tended to underpredict at low work loads (0.5 and 1.0 kp) and overpredicted VO2 at the higher work loads (2.5 kp and greater). The results of this study suggested that in this population of patients with cardiac disease, AE is conducted at a higher cardiorespiratory cost than LE or ALE. The use of ACSM prediction equations warrants additional study regarding this type of lever-action upper-body exercise.

Development and Validation of Total-Work Equations for Estimating the Energy Cost of Walking

The purpose of this study was to develop a walking-energy-cost equation consistent with the concept that the total work (TW) required to walk a given distance is constant. The oxygen uptake of 58 men was measured at walking speeds ranging from 1.7 to 4.1 mph and elevations from 0% to 20%. A least squares solution quantified the influence of speed and percent elevation on oxygen uptake. From these results total-work constants for nine TW models were defined. The models were then validated using metabolic data from 248 healthy men. Next, the optimal TW equation was cross-validated with the metabolic data of 376 men and compared with values calculated from the linear equation of the American College of Sports Medicine (ACSM) and the exponential model of Pandolf, Givoni, and Goldman (PGG). When averaged over all walking intensities, the TW model was more accurate than the ACSM and PGG models. The TW equation duplicated the mean of the actual metabolic work, whereas the ACSM and PGG equations overestimated energy consumption. The average standard error for predicting metabolic energy consumption of the TW model was 1.01 kcal/min as compared with 1.60 kcal/min for the ACSM equation and 1.22 kcal/min for the PGG equation. The results of this study indicated that the total oxygen uptake required to walk one mile on the level is 262.5 mL/kg or 75 MET-min, and 21 mL/kg or 6 MET-min per percent elevation. Using the equation METs X mini mile = 75 + (6 X %), rapid and accurate calculation of the energy cost of walking can be performed.