How Accurate Is the Prediction of Maximal Oxygen Uptake with Treadmill Testing?

Maximal Aerobic Power Using the Modified Heck Protocol: Prediction Models

The purpose of this study was to develop prediction models based on an incremental treadmill test to volitional exhaustion utilizing the modified Heck protocol. A total of 598 professional and youth athletes participating in different sports were recruited for this study. Specifically, the study enrolled professional male soccer players (n=380), professional male futsal players (n=24), elite male basketball players (n=27), professional male soccer referees (n=50), elite female soccer players (n=19), youth male basketball players (13-14 yrs n=15, 15-17 yrs n=20) and youth male soccer players (15 yrs n=28, 16-17 yrs n=35). Anthropometric measurements included stature, body mass, and body fat. Furthermore, all participants performed incremental cardiopulmonary exercise testing on a treadmill using the modified Heck protocol. Through multiple regression analysis, a separate prediction model was developed for each of the athletic populations. Results demonstrated that a significant (p=0.001) proportion of the variation observed in VO₂max was explained by the variation in running time. The generated VO₂max regression equations would allow athletes and coaches to predict VO₂max in a relatively short time without the need for expensive and sophisticated equipment. To our knowledge, this is the first study that provides regression models for different athletic populations using the modified Heck protocol.

Changes Observed in the 6-minute Walk Test in Response to Exercise-based Cardiac Rehabilitation

Objectives: The six-minute walk test (6MWT) is widely used in exercise based cardiac rehabilitation (EBCR) for assessment of functional capacity. The purpose of this study was to assess the effect of structured exercise in an EBCR program on 6MWT change and to determine the significance of age, gender, body mass index (BMI), pathology and exercise attendance on influencing this outcome.Methods: Data from a single centre 6-week (twice weekly exercise and education of one-hour duration) exercise-based cardiac rehabilitation program were analysed. Between 2006 and 2019, 2524 patients (males 1923, females 601, mean age 63.5 ± 11.2 years) with cardiovascular disease completed a pre and post 6MWT. Analysis included the effect of age, gender, pathology, BMI and exercise attendance on 6MWT outcome.Results: The group mean improvement in the 6MWT was 21.8% (pre 6MWT 432 ± 83, post 6MWT 527 ± 102 metres). The age-related improvement showed that both males and females achieved a post 6MWT results equivalent to the pre 6MWT result of patients two decades younger with improvement in the 6MWT unrelated to exercise attendance.Conclusions: The 6MWT provides simple safe method for assessment of functional capacity in an out-of-hospital environment being suitable for all ages. The post EBCR 6MWT results showed a group mean improvement in excess of 20% for both sexes. The decline per decade in 6MWT distance is less than 20 metres up to the sixth decade with a more marked decline from the sixth to the eighth decade, the decline being approximately 40-metres for both sexes in the eighth decade.

Validation of a New Ramping Aerobic Exercise Protocol (NDKS) in Overweight, Obese, and Normal Weight Individuals

The research purpose was to establish reliability and validity of determining VO_2max via a new NDKS (Nustad Dressler Kobes Saghiv; named for the sir names of department faculty at the time) ramping protocol compared to the Standard Bruce protocol in normal weight, overweight, and obese individuals. Forty-two physically active participants (23M, 19F) ages 18-28 years were grouped into normal weight (N = 15, 8F, BMI 18.5-24.9 kg/m²), overweight (N = 27, 11F, BMI = 25-29.9 kg/m²), and Class I obese (N = 7, 1F, BMI = 30-34.9 kg/m²). Blood pressure, heart rate, blood lactate, respiratory exchange ratio, test duration, rate of perceived exertion, and preference via survey were analyzed during each test. Test-retest reliability of the NDKS was determined first, via tests scheduled one week apart. The NDKS was then validated by comparison with results of the Standard Bruce protocol; tests also conducted one week apart. The normal weight group's Cronbach's Alpha was .995 for absolute VO_2max (L/min) and .968 for relative VO_2max (mL/kg·min). Overweight/obese Cronbach's Alpha for absolute VO_2max (L/min) was .960 and for relative VO_2max (mL/kg·min) .908. Relative VO_2max was slightly higher with NDKS and test time lower compared to the Bruce (p < .05). 92.3% of subjects identified more localized muscle fatigue with the Bruce protocol vs NDKS. The NDKS is a reliable and valid exercise test which can be used to determine VO_2max in physically active, young normal weight, overweight and obese individuals.

Use of Heart Rate Index to Predict Oxygen Uptake - A Validation Study

An equation that uses heart rate index (HRI) defined as HR/HRrest to predict oxygen uptake (VO₂) in METs (e.g., METs = 6 × HRI - 5) has been developed retrospectively from aggregate data of 60 published studies. However, the prediction error of this model as used by an individual has not been established. Therefore, the purpose of this study was to examine the predictive validity of the HRI equation by comparing submaximal and maximal VO₂ predicted by the equation (VO₂-Pred) with that measured by indirect calorimetry (VO₂-Meas). Sixty healthy adults (age 20.5 ± 2.4 yr., body mass 69.4 ± 13.4 kg, height 1.7 ± 0.1 m) underwent a VO₂max test and an experimental trial consisting of a 15-min resting measurement and three successive 10-min treadmill exercise bouts performed at 40%, 60% and 80% of VO₂max. VO₂ and HR were recorded during both the submaximal and maximal exercises and used to obtain VO₂-Pred and VO₂-Meas for each intensity and for VO₂max. Validation was carried out by paired t-test, regression analysis, and Bland-Altman plots. A modest but significant (p < 0.05) correlation was observed between VO₂-Meas and VO₂-Pred at 40% (r = 0.58), 60% (r = 0.53), and 80% of VO₂max (r = 0.56) and at VO₂max (r = 0.50). No differences between VO₂-Pred and VO₂-Meas were found at 40% (5.53 ± 1.21 vs. 5.28 ± 0.98 METs, respectively) of VO₂max, but VO₂-Pred was higher (p < 0.05) than VO₂-Meas at 60% (8.42 ± 1.77 vs. 7.96 ± 1.39 METs, respectively) and 80% (10.79 ± 2.13 vs. 10.29 ± 1.81 METs, respectively) of VO₂max. In contrast, VO₂-Pred was lower (p < 0.05) than VO₂-Meas at VO₂max (12.32 ± 2.30 vs. 13.38 ± 2.24 METs, respectively). Standard errors of the estimate were 0.81, 1.20, 1.54, and 1.97 METs at 40%, 60%, 80% of VO₂max and at VO₂max, respectively. These results suggest that further investigation aimed to establish the accuracy of using HRI to predict VO₂ is warranted.

VO2max-Based Physical Fitness Categories in a Brazilian Population with Supposed High Socioeconomic Status and without Structural Heart Disease

Fundamento

Os dados mais utilizados como referência de aptidão cardiorrespiratória (ACR) são os de Cooper, que utiliza valores calculados de captação máxima de oxigênio (VO₂máx).

Objetivo

Desenvolver valores de ACR a partir do teste cardiopulmonar de exercício (TCPE) em uma população brasileira com alto nível socioeconômico e livre de cardiopatia estrutural. Os resultados dos testes de VO₂max foram comparados aos dados de Cooper e do FRIEND Registry.

Métodos

Foram utilizados neste estudo dados de TCPE de indivíduos consecutivos entre 1º de janeiro de 2000 e 31 de maio de 2016. Os critérios de inclusão foram: VO₂máx pré-definido. Foi construído um gráfico de ACR de acordo com os percentuais do VO₂máx: muito ruim (≤20%), ruim (20-40%), regular (40-60%), boa (60-80%), excelente (80-90%), e superior (≥90%). A correlação Kappa foi usada para analisar nossos dados em comparação aos dados dos outros dois bancos de dados. Os testes estatísticos com p<0,005 foram considerados significativos.

Resultados

A coorte final incluiu 18.186 testes: 12.552 homens, 5.634 mulheres (7 a 84 anos). A resposta mais recorrente foi “boa” (20,2%). Houve diferença média de peso, altura, índice de massa corporal (IMC) e idade no gráfico da ACR. Houve correlação inversa entre VO₂máx e idade, peso e IMC. Usando uma regressão linear e essas variáveis, uma equação preditiva foi desenvolvida para o VO₂máx. Nossas descobertas diferiram das dos outros bancos de dados.

Conclusão

Desenvolvemos uma classificação para a ACR e encontramos valores mais altos em todas as faixas de classificação de capacidade funcional, em contraste com os dados de Cooper e do FRIEND Registry. Nossos achados oferecem uma interpretação mais precisa da ACR nessa grande amostra populacional brasileira, quando comparados aos padrões anteriores, com base no VO₂máx estimado. (Arq Bras Cardiol. 2020; 115(3):468-477)

Heart rate-index estimates aerobic metabolism in professional soccer players

OBJECTIVES

This study aimed at proposing a new heart rate (HR) method to track aerobic metabolism in soccer by: (i) validating a recently developed HR index (HR_index) in professional soccer players, (ii) comparing HR_index vs the most common HR parameters and (iii) testing the agreement between measured and estimated VO₂ values using HR_index.

DESIGN

cross-sectional.

METHODS

184 professional soccer players performed a step incremental running test on a treadmill while VO₂ and HR were recorded. HR_index was calculated (actual HR/resting HR) and its relationship with VO₂ was compared with the relationships with the metabolism of actual HR, net HR, and % of HR reserve. Finally, HR_index was used to predict VO₂=((HR_index·6)-5)·3.5) and measured and estimated VO₂ were compared by 2W RM-ANOVA and Bland-Altman analysis.

RESULTS

HR_index/VO₂ relationship explained 85% of the variability in data, showing a higher performance than actual HR (77%) and similar values to the other parameters. Measured and estimated VO₂ were not significantly different ≤14kmh^-1, whereas at speeds ≥14kmh^-1 measured VO₂ was higher than estimated VO₂. Finally, measured and estimated VO₂ were highly correlated (R²=0.85, p=0.000), and showed no significant bias (bias=-1.03, z=-0.69, precision=3.75mlkgmin^-1).

CONCLUSIONS

We validated the HR_index/VO₂ relationship in professional soccer players. HR_index showed better agreement with metabolism than actual HR and similar agreement to the other HR parameters. HR_index allowed to estimate VO₂, but at very high-intensity HR_index underestimated VO₂. Future studies should test this in real game conditions. HR_index could offer a time-efficient and easy-to-use "field" method to monitor aerobic metabolism in soccer.

Incremental shuttle walk test performed in a hallway and on a treadmill: are they interchangeable?

ABSTRACT The performances of healthy individuals in an incremental shuttle walking test performed in a hallway (ISWT-H) and on a treadmill (ISWT-T) were compared to assess their physiological responses during aerobic training sessions with the speeds estimated from both tests. This was a cross-sectional study with 55 healthy subjects, who were randomized to perform the ISWT tests with 24 hours between them. Training sessions were held using a treadmill at 75% of the speeds obtained from the ISWT-H and ISWT-T. Measurements included walking distance, oxygen uptake (VO2), carbon dioxide (VCO2) production, heart rate (HR), and ventilation (VE). There was a significant difference between walking distances (ISWT-T: 823.9±165.2 m and ISWT-H:685.4±141.4 m), but similar physiological responses for VO2 (28.6±6.6 vs. 29.0±7.3 ml-1.kg-1.min-1), VCO2 (1.9±0.7 vs. 1.9±0.5 1), HR (158.3±17.8 vs. 158.6±17.7 bpm), and VE (41.5±10.4 vs. 43.7±12.9 1). The estimated speeds were different for the training sessions (5.5±0.5 km/h and 4.9±0.3 km/h), as well as the VO2, VCO2, VE, and HR. It was concluded that in healthy young adults, ISWTs carried out in a hallway and on a treadmill are not interchangeable. Since the ISWT-H was determined to have lower speed, the training intensity based on this test may underestimate a patient’s responses to aerobic training.

Heart Rate-Index Estimates Oxygen Uptake, Energy Expenditure and Aerobic Fitness in Rugby Players

The purpose of the study was to verify the suitability of heart rate-index (HR_index) in predicting submaximal oxygen consumption (VO₂), energy expenditure (EE) and maximal oxygen consumption (VO_2max) during treadmill running in rugby players. Fifteen professional rugby players (99.8 ± 12.7 kg, 1.85 ± 0.09 m) performed a running incremental test while VO_{2 (}breath-by-breath₎ and heart rate (HR) were measured. HR_index was calculated (actual HR/resting HR) to predict submaximal and maximal VO₂ ({[(HR_index x 6)-5.0] x (3.5 body weight)}) and EE. Measured and predicted VO₂ and EE were compared by two-way RM-ANOVA (method, speed), correlation and Bland-Altman analysis. Measured and predicted VO_2max were compared by paired t-test, correlation and Bland-Altman analysis. Submaximal VO₂ and EE significantly increased (baseline VO₂: 8.1 ± 1.6 ml·kg^-1·min^-1VO_2max: 46.8 ± 4.3 ml·kg^-1·min^-1, baseline EE: 0.03 ± 0.01 kcal·kg^-1·min^-1, peak EE: 0.23 ± 0.03 kcal·kg^-1·min^-1) as a function of speed (p < 0.001 and p < 0.001 for VO₂ and EE respectively) yet measured and predicted values at equal treadmill speeds were not significantly different (p = 0.17; p = 0.16) and highly correlated (r = 0.95; r = 0.94). The Bland-Altman analysis confirmed a non-significant bias between measured and estimated VO₂ (measured: 40.3 ± 10.7, estimated: 40.7 ± 10.1 ml·kg^-1·min^-1, bias = 1.35 ml·kg^-1·min^-1, z = 1.12, precision = 3.39 ml·kg^-1·min^-1) and EE (measured: 20.0 ± 0.05 kcal·kg^-1·min^-1, estimated: 20.0 ± 0.05 kcal·kg^-1·min^-1, bias = 0.00 kcal·kg^-1·min^-1, z = 0.04, precision = 0.02 kcal·kg^-1·min^-1). Estimated and predicted VO_2max were not statistically different (p = 0.91), highly correlated (r = 0.96), and showed a non-significant bias (bias = 0.17, z = 0.22, precision = 1.29 ml·kg^-1·min^-1). HR_index is a valid field method to track VO₂, EE and VO_2max during running in rugby players.

Análise comparativa de fórmulas preditivas de avaliação da capacidade funcional com o teste cardiopulmonar de jogadoras de futebol profissional

RESUMO Comparar a validade de duas fórmulas de predição do consumo de oxigênio (VO2) com os valores obtidos no teste cardiopulmonar (TCP) em esteira ergométrica de jogadoras de futebol profissional. Dezoito jogadoras de futebol profissional foram submetidas ao TCP em esteira em um protocolo de carga incremental. Na sequência, foi determinado o VO2 da potência do limiar anaeróbio ventilatório (LAV) e no pico do exercício físico. Posteriormente, as fórmulas de predição de VO2 - i) VO2 = (0,2 x velocidade) + (0,9 x velocidade x inclinação) + 3,5 - velocidade em mph e inclinação %); e ii) MET (equivalente metabólica) = 6xHRI-5, onde HRI = frequência cardíaca máxima/frequência cardíaca de repouso - foram aplicadas nas mesmas potências para comparação. Para a primeira fórmula foi observado que tanto no LAV como no pico do TCP, os dados obtidos ficaram abaixo do previsto, sugerindo que a fórmula superestima o VO2 e, consequentemente, a capacidade e a potência aeróbicas. Na segunda fórmula foi observado que os valores ficaram abaixo do obtido, sugerindo que a fórmula subestimou o VO2 e, consequentemente a potência aeróbica, e mais uma vez a capacidade funcional. Diante disso, as fórmulas de predição não mostraram similaridade na determinação da capacidade funcional (CF) de jogadoras de futebol profissional, sugerindo não serem recomendadas para essa população.