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Validity and reliability of a submaximal cycle ergometer test for estimation of maximal oxygen uptake
Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Åstrand Laboratory of Work Physiology.ORCID iD: 0000-0001-8353-3766
2017 (English)Doctoral thesis, comprehensive summary (Other academic)Alternative title
Validitet och reliabilitet hos ett submaximalt cykelergometertest för estimering av maximal syreupptagningsförmåga (Swedish)
Abstract [en]

Maximal oxygen uptake (VO2max) is the highest obtained rate of oxygen consumption during a physically intense dynamic whole-body activity. VO2max is an important factor for many types of physical performance, as well as a strong independent predictor of health and longevity. Thus, it is important to have accurate and precise methods for assessment of VO2max.

A direct measurement of VO2max is often conducted via indirect calorimetry during maximal exercise. The demand for maximal effort from an individual, along with the need for laboratory equipment, makes direct measurements unsuitable in the general, non-athlete population. There are also a number of contraindications that limit the possibility to conduct direct measurements of VO2max in many settings. Instead, several other exercise tests have been developed in order to facilitate the procedure of determination and evaluation of cardiorespiratory fitness in different populations. These tests can be either of submaximal or maximal character. Commonly used work modes are stepping, walking, and cycling. The overall aim of this thesis was to describe the background to, and the development of, submaximal cycle ergometer tests for estimation of VO2max.

The present thesis focuses on the validity and reliability of a new submaximal cycle ergometer test – the Ekblom-Bak test (EB test). The first study described the test procedure for the new cycle ergometer test and the creation of an accompanying mathematical model (prediction equation) for estimation of VO2max. The development of the test and its associated prediction equation was continued in study II, while it was further validated in adults and adolescents in study II and IV. Study III examined the ability to use a submaximal cycle ergometer test in order to detect changes in VO2max over time.

The EB test comprises of 8 minutes of continuous cycling – 4 minutes at 0.5 kp, followed by 4 minutes at a higher, individually chosen work rate – with a pedalling rate of 60 revolutions per minute. The test measures the change in HR (ΔHR) between the two different work rates (ΔPO), and the variable ΔHR/ΔPO was obtained and linked to measured VO2max. In study I, the validity and reliability of the EB test and the associated prediction equation was tested in a mixed population with regard to sex, age, and physical activity status. The subjects performed repeated submaximal cycle ergometer tests and maximal running tests for direct determination of VO2max (reference value). There was a strong correlation between estimated and measured VO2max, with an adjusted R2 of 0.82 and a corresponding coefficient of variation (CV) of 9.3%. Although there was a relatively high precision in the estimation of VO2max by the prediction equation, it was evident that individuals with high VO2max were underestimated and individuals with low VO2max were overestimated. This issue was further addressed in study II.

In study II, the size of the study population was increased, in order to broaden the valid range and evaluate the use of sex-specific prediction equations. The estimation error was slightly decreased, and the sex-specific prediction equations resulted in an adjusted R2 of 0.91 and a CV of 8.7% in the whole group. The new models were also evaluated in a cross-validation group, where the adjusted R2 was 0.90 and CV 9.4%.

The relation between the estimation error and changes in VO2max over time was investigated in study III. Follow-up tests were conducted in 35 subjects, in order to examine the conformity between changes in measured and estimated VO2max over a timespan of 5 to 8 years. Results showed a moderate correlation between change in measured VO2max and change in estimated VO2max (r = 0.75). Changes in body mass or changes in work efficiency did not relate to the change in assessment error. 

In study IV, the aim was to determine the applicability and validity of the EB test in pre-pubertal and pubertal adolescents. Medical examinations and assessment of sexual maturity (according to the stages of Tanner) were performed in addition to the physical tests. The included subjects (n = 50) were 10 to 15 years old and in Tanner stages I–IV. The measurement error (the difference between measured and estimated VO2max) was related to maturity in boys, but not in girls. The measurement error decreased for the whole group when the equation developed for women was used for the boys in Tanner I and II. This modification in the calculations of VO2max resulted in an adjusted R2 of 0.83 and SEE 0.23 L/min. Hence, the most accurate prediction of VO2max from the EB test is generated if the test result is accompanied by ratings of sexual maturity in adolescents. Analysis of the test-retest values showed no significant change in estimated VO2max from repeated tests within two weeks of each other. 

In summary, the EB test proved to be a reliable and valid test throughout a wide range of ages (20 to 85 years) and fitness levels (1.33 to 3.94 L/min in women, and 1.67 to 5.97 L/min in men). The test was also found to be useful and reasonably valid for determination of VO2max in pre-pubertal and pubertal adolescents, preferably after adjustment for sexual maturity status in boys. Furthermore, it was shown that the EB test captured fairly well an actual change in VO2max during a period of 5 to 8 years. However, it is still unknown whether the test has an acceptable sensitivity for detection of a training-induced increase in VO2max. Further studies are needed to evaluate if the test can be used in diseased individuals with or without different medications. The EB test can be used in health-related clinical settings, sports and fitness clubs.

Place, publisher, year, edition, pages
Stockholm: Gymnastik- och idrottshögskolan, GIH , 2017. , 126 p.
Series
Avhandlingsserie för Gymnastik- och idrottshögskolan, 11
National Category
Sport and Fitness Sciences
Research subject
Medicine/Technology
Identifiers
URN: urn:nbn:se:gih:diva-5095ISBN: 978-91-983151-2-7 (print)OAI: oai:DiVA.org:gih-5095DiVA: diva2:1158890
Public defence
2017-12-15, Aulan, Lidingövägen 1, Stockholm, 09:00 (English)
Opponent
Supervisors
Available from: 2017-11-21 Created: 2017-11-21 Last updated: 2017-11-23Bibliographically approved
List of papers
1. A new submaximal cycle ergometer test for prediction of VO(2max).
Open this publication in new window or tab >>A new submaximal cycle ergometer test for prediction of VO(2max).
2014 (English)In: Scandinavian Journal of Medicine and Science in Sports, ISSN 0905-7188, E-ISSN 1600-0838, Vol. 24, no 2, 319-326 p.Article in journal (Refereed) Published
Abstract [en]

Maximal oxygen uptake (VO(2max) ) is an important, independent predictor of cardiovascular health and mortality. Despite this, it is rarely measured in clinical practice. The aim of this study was to create and evaluate a submaximal cycle ergometry test based on change in heart rate (HR) between a lower standard work rate and an individually chosen higher work rate. In a mixed population (n = 143) with regard to sex (55% women), age (21-65 years), and activity status (inactive to highly active), a model included change in HR per unit change in power, sex, and age for the best estimate of VO(2max) . The association between estimated and observed VO(2max) for the mixed sample was r = 0.91, standard error of estimate = 0.302 L/min, and mean measured VO(2max)  = 3.23 L/min. The corresponding coefficient of variation was 9.3%, a significantly improved precision compared with one of the most commonly used submaximal exercise tests, the Åstrand test, which in the present study was estimated to be 18.1%. Test-retest reliability analysis over 1 week revealed no mean difference in the estimated VO(2max) (-0.02 L/min, 95% confidence interval: -0.07-0.03). The new test is low-risk, easily administered, and valid for a wide capacity range, and is therefore suitable in situations as health evaluations in the general population.

National Category
Medical and Health Sciences
Research subject
Medicine/Technology
Identifiers
urn:nbn:se:gih:diva-2480 (URN)10.1111/sms.12014 (DOI)23126417 (PubMedID)
Projects
Långvarigt stillasittande
Available from: 2012-11-19 Created: 2012-11-19 Last updated: 2017-12-07Bibliographically approved
2. Validity of the revised Ekblom Bak cycle ergometer test in adults.
Open this publication in new window or tab >>Validity of the revised Ekblom Bak cycle ergometer test in adults.
2016 (English)In: European Journal of Applied Physiology, ISSN 1439-6319, E-ISSN 1439-6327, Vol. 116, no 9, 1627-1638 p.Article in journal (Refereed) Published
Abstract [en]

PURPOSE: To further develop the Ekblom Bak-test prediction equation for estimation of VO2max from submaximal cycle ergometry.

METHODS: The model group (117 men and 100 women, aged 48.3 ± 15.7 and 46.1 ± 16.8 years, VO2max 46.6 ± 11.1 and 40.4 ± 9.6 mL kg(-1) min(-1), respectively) and the cross-validation group (60 men and 55 women, aged 40.6 ± 17.1 and 41.6 ± 16.7 years, VO2max 49.0 ± 12.1 and 43.2 ± 8.9 mL min(-1) kg(-1), respectively) performed 4 min of cycling on a standard work rate (30 W) directly followed by 4 min on a higher work rate. Heart rate (HR) at each work rate was recorded. Thereafter, participants completed a graded maximal treadmill test for direct measurement of oxygen uptake. The new prediction equation was cross-validated and accuracy compared with the original Ekblom Bak equation as well as by the Åstrand test method.

RESULTS: The final sex-specific regression models included age, change in HR per-unit change in power (ΔHR/ΔPO), the difference in work rates (ΔPO), and HR at standard work rate as independent variables. The adjusted R (2) for the final models were 0.86 in men and 0.83 in women. The coefficient of variation (CV) was 8.7 % and SEE 0.28 L min(-1). The corresponding CV and SEE values for the EB-test2012 and the Åstrand tests were 10.9 and 18.1 % and 0.35 and 0.48 L min(-1), respectively.

CONCLUSION: The new EB-test prediction equation provides an easy administered and valid estimation of VO2max for a wide variety of ages (20-86 years) and fitness levels (19-76 mL kg(-1) min(-1)).

National Category
Sport and Fitness Sciences
Research subject
Medicine/Technology
Identifiers
urn:nbn:se:gih:diva-4474 (URN)10.1007/s00421-016-3412-0 (DOI)000384214300002 ()27311582 (PubMedID)
Projects
Långvarigt stillasittande
Available from: 2016-06-21 Created: 2016-06-21 Last updated: 2017-11-28
3. The ability of a submaximal cycle ergometer test to detect changes in VO2max
Open this publication in new window or tab >>The ability of a submaximal cycle ergometer test to detect changes in VO2max
(English)Manuscript (preprint) (Other academic)
Keyword
cycle ergometer test, follow-up, maximal oxygen uptake
National Category
Sport and Fitness Sciences
Research subject
Medicine/Technology
Identifiers
urn:nbn:se:gih:diva-5094 (URN)
Note

At the time of Frida Björkman's disertation this was a manuscript.

Available from: 2017-11-21 Created: 2017-11-21 Last updated: 2017-11-21Bibliographically approved
4. Sex and maturity status affected the validity of a submaximal cycle test in adolescents.
Open this publication in new window or tab >>Sex and maturity status affected the validity of a submaximal cycle test in adolescents.
Show others...
2017 (English)In: Acta Paediatrica, ISSN 0803-5253, E-ISSN 1651-2227Article in journal (Refereed) Epub ahead of print
Abstract [en]

AIM: This study assessed the validity and reliability of the Ekblom-Bak (EB) submaximal cycle test in adolescents and identified any sex- or maturity-related factors for prediction errors.

METHODS: We recruited 50 healthy subjects through a public announcement in Stockholm, Sweden, in 2016. The 27 boys and 23 girls were aged 10-15 years and in Tanner stages I-IV. They performed an EB test and incremental treadmill running test for direct measurement of maximal oxygen uptake (VO2 max).

RESULTS: The estimation error of VO2 max was 0.09 L/min. The correlation (r) was 0.86, and the standard error of the estimate (SEE) was 0.29 L/min. The largest overestimation was seen in prepubertal boys (0.49 L/min). The best precision of the EB test was achieved when boys in Tanner stages I and II were re-calculated using the prediction equation developed for adult women. This yielded a mean difference of -0.05 L/min, r = 0.92 and SEE 0.23 L/min, in the entire sample. The prediction error was lowered in boys, but not girls, with increasing pubertal maturity.

CONCLUSION: The EB test was reasonably valid in adolescents, seemed to be related to sex and maturity status, and our findings support its use.

Keyword
Ergometry, Exercise test, Maximal oxygen uptake, Physical fitness, Sexual maturation
National Category
Sport and Fitness Sciences
Research subject
Medicine/Technology
Identifiers
urn:nbn:se:gih:diva-5061 (URN)10.1111/apa.14080 (DOI)28925577 (PubMedID)
Available from: 2017-11-07 Created: 2017-11-07 Last updated: 2017-11-21Bibliographically approved

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