Evaluation of three methodologies to estimate the VO2max in people of different ages

A Practice Guide for Physical Therapists Prescribing Physical Exercise for Older Adults

INTRODUCTION

Physical activity and exercise are protective factors for physical and cognitive decline in older adults, but recent studies reveal that a large percentage of this population do not practice exercise at the levels recommended by international guidelines. The frequency, intensity, type, time, volume, and progression (FITT-VP) principles are a widely used method for prescribing physical exercise, allowing the development of a personalized exercise program that meets the needs of each individual.

OBJECTIVES

This masterclass is intended to serve as a professional application tool for physical therapists who prescribe physical exercise for older adults. We present a section for each FITT-VP principle to facilitate handling these principles individually when prescribing exercise for this population.

METHODS

Review of the scientific literature and international guidelines on the prescription of physical exercises for older adults.

RESULTS

Aerobic, mobility, resistance, balance, and flexibility exercises, as well as functional training, should be included in an exercise program for older adults, which should be progressed using different methods for each of the exercise modalities.

CONCLUSIONS

An exercise program for older adults should integrate different exercise modalities. Exercise progression should be performed following the FITT-VP principles and some specific progression factors recommended for each exercise modality.

SIGNIFICANCE

Considering the challenge faced by clinicians in designing a viable exercise program for older adults that responds to international recommendations, with this masterclass we hope to help physical therapists to plan an exercise program that is feasible and at the same time, responds to the expected needs of this population.

Heart Rate Variability Based Estimation of Maximal Oxygen Uptake in Athletes Using Supervised Regression Models

Wearable Heart Rate monitors are used in sports to provide physiological insights into athletes' well-being and performance. Their unobtrusive nature and ability to provide reliable heart rate measurements facilitate the estimation of cardiorespiratory fitness of athletes, as quantified by maximum consumption of oxygen uptake. Previous studies have employed data-driven models which use heart rate information to estimate the cardiorespiratory fitness of athletes. This signifies the physiological relevance of heart rate and heart rate variability for the estimation of maximal oxygen uptake. In this work, the heart rate variability features that were extracted from both exercise and recovery segments were fed to three different Machine Learning models to estimate maximal oxygen uptake of 856 athletes performing Graded Exercise Testing. A total of 101 features from exercise and 30 features from recovery segments were given as input to three feature selection methods to avoid overfitting of the models and to obtain relevant features. This resulted in the increase of model's accuracy by 5.7% for exercise and 4.3% for recovery. Further, post-modelling analysis was performed to remove the deviant points in two cases, initially in both training and testing and then only in training set, using k-Nearest Neighbour. In the former case, the removal of deviant points led to a reduction of 19.3% and 18.0% in overall estimation error for exercise and recovery, respectively. In the latter case, which mimicked the real-world scenario, the average R value of the models was observed to be 0.72 and 0.70 for exercise and recovery, respectively. From the above experimental approach, the utility of heart rate variability to estimate maximal oxygen uptake of large population of athletes was validated. Additionally, the proposed work contributes to the utility of cardiorespiratory fitness assessment of athletes through wearable heart rate monitors.

Prediction of maximal oxygen uptake based on anthropometric indices in Iranian male adults

BACKGROUND

Assessment of maximal oxygen consumption is important in both general community and occupational settings. Validity and reliability tests are needed to indicate the functionality of the cardiopulmonary system.

OBJECTIVE

This study aimed to establish a maximal oxygen consumption (VO2max) prediction model using anthropometric and demographic variables for young adults in Iran.

METHODS

This cross-sectional study was conducted on 64 healthy young men aged 19-29 years. Oxygen consumption was measured directly and the prediction models to estimate VO2max were determined by multiple linear regression. The accuracy of the prediction models was considered using regression coefficient (R), coefficient of determination (R2), and standard error of estimate (SEE).

RESULTS

The average VO2max was 44.02±4.31 ml/kg/min. Significant correlations were found between the measured VO2max and the anthropometric and demographic variables (r = 0.16-0.86, P < 0.05). Three significant regression models with acceptable accuracy were developed (R2 = 0.67-0.71, SEE = 3.19-3.21).

CONCLUSION

The predictive models consisted of 3-5 variables as significant predictors of VO2max and had acceptable accuracy for Iranian young adults. The proposed models are a simple and valid tool that can be used to estimate the VO2max in the field and in laboratory settings.

Enhancing the assessment of cardiorespiratory fitness using field tests

OBJECTIVE

To establish normative values and reference equations of the 6-minute walk test (6MWT), incremental shuttle walk test (ISWT) and unsupported upper limb exercise test (UULEX) for Portuguese adults.

DESIGN

Cross-sectional study. Descriptive statistics and differences between age decades and genders were explored using univariate general linear models to compute reference values. Reference equations were established with a forward stepwise multiple regression.

SETTING

General community.

PARTICIPANTS

In total, 645 adult volunteers without disabilities [43% male, mean age 55.1 (standard deviation 23.6) years] were recruited from the university campus and surrounding community.

INTERVENTION

Not applicable.

MAIN OUTCOME MEASURES

Data on age, gender, height, weight, body mass index and smoking status were collected using a structured questionnaire. Physical activity was evaluated using the Brief Physical Activity Assessment Tool. Participants performed two repetitions of the 6MWT, ISWT and UULEX, and the best repetition was used for analysis.

RESULTS

Overall, performance was better in males than in females, and decreased with age. Participants' performance was significantly reduced after the sixth decade of life compared with the other decades (P<0.001). Reference equations were: 6MWT=226.93-(5.00×age)+(360.41×height), R²=71%; ISWT=393.81-(17.98×age)+(185.64×gender)+(775.88×height), R²=83%; and UULEX=16.71-(0.14×age)+(2.66×gender), R²=57%.

CONCLUSION

Leg or arm exercise field tests are affected significantly by age and gender. These results will aid health professionals to interpret the results of field tests obtained from healthy or diseased adult populations.

The Validity of the YMCA 3-Minute Step Test for Estimating Maximal Oxygen Uptake in Healthy Korean and Vietnamese Adults

Background

Cardiorespiratory fitness (CRF) is a fundamental component of physical fitness. While maximal oxygen uptake (VO₂max) is the gold standard for quantifying CRF, standard maximal exercise tests using direct measurements VO₂max are dependent on the availability of laboratory equipment, and thereby expensive and time consuming. Recently, an equation was formulated to indirectly estimate VO₂max using the YMCA 3-minute step test.

Methods

The study included 15 Korean (KR) and 15 Vietnamese (VN) healthy adults aged 19-35 years. All subjects completed a YMCA 3-minute step test (YMCA 3MST) and a maximal exercise treadmill test to predict VO₂max and VO₂max measures, respectively.

Results

There was a significant relationship between VO₂max predicted from the YMCA 3MST and actual VO₂max measurements from the treadmill test (r = 0.80, p < 0.0001; KR group: r = 0.81, p < 0.0001; VN group: r = 0.93, p < 0.0001). Bland-Altman analysis revealed statistical agreement between tests, although there was a systematic overestimation of 3.36 mL/kg/min for the KR group.

Conclusion

The equation for predicting VO₂max from the YMCA 3MST was validated among the study subjects. However, future research should explore the validity and reliability of the YMCA 3MST equation for estimating VO₂max in other populations.

Validity of Submaximal Step Tests to Estimate Maximal Oxygen Uptake in Healthy Adults

BACKGROUND

Aerobic capacity (VO2max) is a strong predictor of health and fitness and is considered a key physiological measure in the healthy adult population. Submaximal step tests provide a safe, simple and ecologically valid means of assessing VO2max in both the general population and a rehabilitation setting. However, no studies have attempted to synthesize the existing knowledge regarding the validity of the multiple step-test protocols available to estimate VO2max in the healthy adult population.

OBJECTIVES

The objective of this study was to systematically review literature on the validity and reliability of submaximal step-test protocols to estimate VO2max in healthy adults (age 18-65 years).

DATA SOURCES AND STUDY SELECTION

A systematic literature search of the MEDLINE, EMBASE, Scopus, Web of Science, and Cochrane Library databases was performed. The search returned 690 studies that underwent the initial screening process. To be included, the study had to (1) have participants deemed to be healthy and aged between 18 and 65 years; (2) assess VO2max by means of a submaximal step test against a graded exercise test (GXT) to volitional exhaustion; and (3) be available in English. Reference lists from included articles were screened for additional articles.

DATA ANALYSIS AND STUDY APPRAISAL METHODS

The primary outcome measures used were the validity statistics between the actual measured VO2max and predicted VO2max values, and the reported direction of the statistically significant difference between the measured VO2max and the predicted VO2max. The Quality Assessment Tool for Quantitative Studies was used to assess the risk of bias in each included study, and was adapted to the type of quantitative study design used.

RESULTS

The combined database search produced 690 studies, from which 644 were excluded during the screening process. Following full-text assessment, a further 39 studies were excluded based on the eligibility criteria detailed previously. Four additional studies were located via the reference lists of the included studies, leaving 11 studies that fulfilled the inclusion criteria and which compared eight different step-test protocols against a direct measure of VO2max incurred during a maximal GXT. Validity measures varied, with a broad range of correlation coefficients reported across the 11 studies (r = 0.469-0.95). Of the 11 studies, two reported reliability measures, demonstrating good test-retest reliability [mean -0.8 ± 3.7 mL kg(-1) min(-1) (±7.7 % of the mean measured VO2max)].

CONCLUSIONS

Considering the relationship between VO2max and various markers of health, the use of step tests as a measure of health in both the general adult population and rehabilitation settings is advocated. Step tests provide a simple, effective and ecologically valid method of submaximally assessing VO2max that can be implemented in a variety of situations within the general adult population. Future research is needed to assess the reliability of the majority of the step-test procedures reviewed. Based on the validity measures, submaximal step-test protocols are an acceptable means of estimating VO2max in the generally healthy adult population. For tracking changes in cardiorespiratory fitness, the Chester Step test appears to be an appropriate tool due to its high test-retest reliability.

Cardiovascular fitness strengthening using portable device

The paper describes a reliable and valid Portable Exercise Monitoring system developed using TI eZ430-Chronos watch, which can control the exercise intensity through audio stimulation in order to increase the Cardiovascular fitness strengthening.

Inflammatory Biomarkers' Response to Two Different Intensities of a Single Bout Exercise Among Soccer Players

Background:

There is a strong relationship between physical inactivity and low-grade inflammation and its adverse health outcomes, particularly cardiovascular disease. The level of anti-inflammatory and pro-inflammatory cytokines may be changed by exercise.

Objectives:

The aim of the present study was to determine the response of certain inflammatory biomarkers to exercise with differences in maximal oxygen consumption (VO_2max). These biomarkers were IL-1β, TNF-α, hs-CRP, IL-6, sICAM-1, IL-10, and ratios of TNF-α/IL-10 and IL-6/IL-in circulating peripheral blood (PB).

Materials and Methods:

In a semi-experimental study, twenty male students who performed regular football exercise at least three days a week, for two years, were selected by easy sampling at Shahid Chamran university of Iran. Subjects were then randomly assigned to two groups: the protocol of the first group was 30 minutes of running at a speed of 65% of VO_2max, and the second group performed six periodic repetitions with three minutes at a speed of 85% of VO2max with a 90-second rest between the repetitions. Blood samples were taken at baseline, immediately after the exercise and at rest. Cytokine levels were quantified by the Sandwich enzyme-linked immunosorbent assay (ELISA) method.

Results:

The first protocol resulted in a decrease of serum IL-1β to 3.77 ± 0.28 pg/mL at rest, from 4.33 ± 0.28 at baseline and 4.32 ± 0.34 immediately after exercise (P = 0.008 and P = 0.013, respectively). There was also a decrease in the level of sICAM-1 to 260.11±15.64 ng/mL at rest, from 329.58 ± 20.82 at baseline and 302.7 ± 20.49 post exercise (P = 0.013 and P = 0.038, respectively). On the other hand, IL-6 and ratio of IL-6/IL-10 increased to 6.55±0.84 pg/mL and 2.12 ± 0.37 immediately after exercise from baseline (2.73 ± 0.58 and 1.16 ± 0.33) and rest (2.49 ± 0.45 and 0.95 ± 0.19) in the second protocol (P = 0.001 and P = 0.001, respectively for IL-6, and P = 0.047 and P = 0.024, respectively for IL-6/IL-10).

Conclusions:

The data of the present study demonstrated that a single bout of exercise with higher-intensity induces a transient increase in some proinflammatory markers, and lower-intensity can reduce these biomarkers.

Can we use the 6-minute step test instead of the 6-minute walking test? An observational study

OBJECTIVE

To verify whether or not heart rate is maintained below the calculated submaximal level in healthy, sedentary subjects when they perform the 6-minute step test (6MST) and the 6-minute walking test (6MWT), and to compare the maximal heart rate achieved by the subjects at the end of each test.

DESIGN

Observational, cross-sectional study.

SETTING

One tertiary centre.

PARTICIPANTS

Two hundred and fifty-three participants from a pool of 330 healthy and sedentary subjects between 20 and 80 years of age.

INTERVENTIONS

Both the 6MWT and the 6MST were performed in accordance with the American Thoracic Society's statement. Dyspnoea, blood pressure, oxygen saturation and heart rate were measured before and after each test.

RESULTS

Mean heart rate immediately after the 6MST was significantly higher than mean heart rate immediately after the 6MWT {125 [standard deviation (SD) 19] vs 111 (SD 17) beats/minute; mean difference 13 (95% confidence interval of the difference 10 to 16); P<0.001}. Moreover, mean heart rate during (3minutes after commencement) the 6MST [118 (SD 18) beats/minute] was statistically higher than mean heart rate at the end of the 6MWT [111 (SD 18) beats/minute; P<0.001]. None of the subjects achieved the calculated submaximal heart rate.

CONCLUSIONS

The 6MST and 6MWT are safe and produce submaximal effort in healthy participants. However, they are not interchangeable, and the 6MST requires more energy than the 6MWT.

Development and validation of an automated step ergometer

Laboratory ergometers have high costs, becoming inaccessible for most of the population, hence, it is imperative to develop affordable devices making evaluations like cardiorespiratory fitness feasible and easier. The objective of this study was to develop and validate an Automated Step Ergometer (ASE), adjusted according to the height of the subject, for predicting VO2max through a progressive test. The development process was comprised by three steps, the theoretical part, the prototype assembly and further validation. The ASE consists in an elevating platform that makes the step at a higher or lower level as required for testing. The ASE validation was obtained by comparing the values of predicted VO2max (equation) and direct gas analysis on the prototype and on a, treadmill. For the validation process 167 subjects with average age of 31.24 ± 14.38 years, of both genders and different degrees of cardiorespiratory fitness, were randomized and divided by gender and training condition, into untrained (n=106), active (n=24) and trained (n=37) subjects. Each participant performed a progressive test on which the ASE started at the same height (20 cm) for all. Then, according to the subject's height, it varied to a maximum of 45 cm. Time in each stage and rhythm was chosen in accordance with training condition from lowest to highest (60-180 s; 116-160 bpm, respectively). Data was compared with the student's t test and ANOVA; correlations were tested with Pearson's r. The value of α was set at 0.05. No differences were found between the predicted VO2max and the direct gas analysis VO2max, nor between the ASE and treadmill VO2max (p= 0.365) with high correlation between ergometers (r= 0.974). The values for repeatability, reproducibility, and reliability of male and female groups measures were, respectively, 4.08 and 5.02; 0.50 and 1.11; 4.11 and 5.15. The values of internal consistency (Cronbach's alpha) among measures were all >0.90. It was verified that the ASE prototype was appropriate for a step test, provided valid measures of VO2max and could therefore, be used as an ergometer to measure cardiorespiratory fitness.

Modelling and regulating of cardio-respiratory response for the enhancement of interval training

BACKGROUND

The interval training method has been a well known exercise protocol which helps strengthen and improve one's cardiovascular fitness.

PURPOSE

To develop an effective training protocol to improve cardiovascular fitness based on modelling and analysis of Heart Rate (HR) and Oxygen Uptake (VO2) dynamics.

METHODS

In order to model the cardiorespiratory response to the onset and offset exercises, the (K4b2, Cosmed) gas analyzer was used to monitor and record the heart rate and oxygen uptake for ten healthy male subjects. An interval training protocol was developed for young health users and was simulated using a proposed RC switching model which was presented to accommodate the variations of the cardiorespiratory dynamics to running exercises. A hybrid system model was presented to describe the adaptation process and a multi-loop PI control scheme was designed for the tuning of interval training regime.

RESULTS

By observing the original data for each subject, we can clearly identify that all subjects have similar HR and VO2 profiles. The proposed model is capable to simulate the exercise responses during onset and offset exercises; it ensures the continuity of the outputs within the interval training protocol. Under some mild assumptions, a hybrid system model can describe the adaption process and accordingly a multi-loop PI controller can be designed for the tuning of interval training protocol. The self-adaption feature of the proposed controller gives the exerciser the opportunity to reach his desired setpoints after a certain number of training sessions.

CONCLUSIONS

The established interval training protocol targets a range of 70-80% of HRmax which is mainly a training zone for the purpose of cardiovascular system development and improvement. Furthermore, the proposed multi-loop feedback controller has the potential to tune the interval training protocol according to the feedback from an individual exerciser.

Recumbent stepper submaximal exercise test to predict peak oxygen uptake

PURPOSE

The purpose of this study was to examine the ability of the YMCA submaximal exercise test protocol using a total body recumbent stepper to predict V˙O(2peak).

METHODS

Of 112 individuals initially screened, 110 individuals with low to moderate cardiovascular disease risk met the inclusion criteria for participation in the study. The maximal exercise test used a motorized treadmill and the Bruce or modified Bruce protocol. Oxygen uptake was measured and analyzed through collection of expired gases using a metabolic measurement system. The submaximal exercise test was performed at least 24 h later but no more than 5 d after maximal exercise testing. Participants were instructed to keep a pace of 100 steps per minute and the resistance increase every 3 min according to the protocol until fatigue, or until 85% of HR max was achieved. A cross-validation study was also performed to determine the accuracy of the prediction equation.

RESULTS

Using a stepwise regression, we report that V˙O(2peak) can be predicted using a five-element model including age, weight, sex, wattsend_submax, and HRend_submax (F5,69 = 70.31, P < 0.001). We report a strong correlation between the predicted V˙O(2peak) to the actual V˙O(2peak).

CONCLUSIONS

These data suggest the YMCA submaximal exercise test can be used with the total body recumbent stepper to predict V˙O(2peak) in healthy adults.

Physical Capability Scale

The purpose of this study was to describe the psychometric testing of the Basic Physical Capability Scale. The study was a secondary data analysis of combined data sets from three studies. Study participants included 93 older adults, recruited from 2 acute-care settings and 110 older adults living in long-term care facilities. Rasch analysis was used for the testing of the measurement model. There was some support for construct validity based on the fit of the items to the scale across both samples. In addition, there was support for hypothesis testing as physical function was significantly associated with physical capability. There was evidence for internal consistency (Alpha coefficients of .77-.83) and interrater reliability based on an intraclass correlation of .81. This study provided preliminary support for the reliability and validity of the Basic Physical Capability Scale, and guidance for scale revisions and continued use.