Estimation of maximal oxygen uptake from the 3,000 m run in adult men and women

Estimation of peak oxygen pulse from body mass, resting heart rate, age, gender and systolic blood pressure in Chinese adults aged 20-39

Background

Peak oxygen pulse (O2Ppeak) can reflect the condition of cardiovascular function and provide supplementary information for maximal oxygen uptake, but its direct measurement requires the precise instruments under the guidance of professionals, and the subjects should strive to the state of exhaustion.

Objectives

The aim of the present cross-sectional study was to establish a prediction equation to estimate O2Ppeak of Chinese adults aged 20-39, from routine measures of anthropometry and cardiovascular function.

Methods

252 adults (20-39 years old) were recruited and randomly allocated to the validation group (n = 226) and the cross-validation group (n = 26). To be included in the study, subjects were required to be healthy, none-professional sports experience (healthy individuals who are not athletes or have had experience as athletes), and no medication taken recently. Subjects with cardiovascular diseases, lung disease and musculoskeletal diseases were excluded. The subjects' anthropometric and cardiovascular variables were measured and each subject performed a maximal exercise test on an electromagnetic cycle ergometer.

Results

The O2Ppeak estimated equation was developed using multiple linear regression models, O2Ppeak = 30.394 + 0.083 x body mass (kg) - 0.090 x resting heart rate (bpm) - 0.157 x age (years) - 2.710 x gender (1 = male, 2 = female) - 0.035 x systolic blood pressure (mmHg). The equation had the coefficient of determination (R2) = 0.804 and the standard error of estimate (SEE) = 1.619 ml/beat. An ANOVA and Akaike's information criterion (AIC) were tested. Bland-Altman graphs were plotted to examine the distribution of bias. Cross-validation estimated O2Ppeak and directly measured O2Ppeak did not show significant difference while had a strong positive correlation (r = 0.89, p < 0.001).

Conclusions

The established equation has high effectiveness and reliability to predict O2Ppeak of adults aged 20-39.

Relationship between self-reported and objectively measured physical fitness in young men and women

Self-reported physical fitness has advantages in cost and time over objective methods, but previous studies demonstrate equivocal conclusions regarding validity. Methods for self-reporting are usually based on subjective judgements, while another approach includes performing field tests at home. The Norwegian military relies on the latter method for conscript selection, but its validity is unknown and should be investigated. In total 14,166 young men and women were included in the study. During conscript selection step one, the subjects were requested to perform 3,000 m run, push-up, pull-up and standing long jump tests at home, and report the results online ("self-reported measurements"). Step two took place at a conscript selection centre 1-18 months later. Here, the subjects completed a maximal treadmill test, seated medicine ball throw, pull-up and standing long jump tests ("objective measurements"). The results demonstrated correlation coefficients from 0.29 to 0.82 (P < 0.05) for self-reported vs. objective measurements, with the highest association found for self-reported and objectively measured pull-ups. Kappa values ranged from 0.05 to 0.34 (P < 0.05), with pull-ups demonstrating the highest agreement. More women than men over-reported their physical fitness. Among men and women indicating similar self-reported fitness, men's objective fitness was higher for all objective tests (effect sizes from 0.5 to 3.0). In conclusion, large variations in correlation coefficients were observed between self-reported and objectively measured physical fitness, while the kappa values indicated poor to fair agreement. The finding that more women than men over-reported their fitness level contradicts most previous studies.Highlights Low, moderate, and high correlations, and poor to fair agreements (kappa values), were observed between self-reported and objectively measured endurance and muscle strength variables.More women than men overreported their actual fitness level.Self-reported fitness based on performing field tests at home may be a feasible alternative to traditional methods which rely on self-perceived fitness.

Temporal changes in physical fitness in Norwegian male and female military conscripts between 2006 and 2020

Reduced physical fitness has been documented in Western children and adults over the past five decades. The same trend has been observed among soldiers, but the number of studies is scarce. Thus, the aim of the present study was to investigate temporal changes in physical fitness in Norwegian conscripts. All conscripts who performed entry fitness tests between 2006 and 2020 were included in the study (n = 105 100; 17% females). Endurance was measured with the 3000 m run, while push-ups, sit-ups, and pull-ups (2006-2016) and medicine ball throw, standing long jump, and pull-ups (2017-2020) were used to measure muscle strength. Mean (95% confidence intervals) 3000 m run time was reduced by 52 (47, 57) seconds in men, 90 (76, 105) seconds in women, and 16 (11, 20) seconds in both sexes combined. Muscle strength increased statistically significantly in four out of five tests in men, three out of six tests in women, and two out of five tests for both sexes combined. Effect sizes for statistically significant changes ranged from 0.06 to 0.82. In conclusion, Norwegian conscripts improved their cardiorespiratory endurance between 2006 and 2020, with improvements observed for most muscle strength tests. When analyzing both sexes combined, the improvements diminished. The latter is attributed to a sevenfold increase in relative number of female conscripts over the 15-year period. The present findings should not be generalized to all young Norwegian men and women since conscripts are selected based on fitness, and only ~15% of the population end up serving.

Self-Perceived and Self-Tested Endurance: Associations with Objective Measures

Use of self-report (questionnaires) is often the most realistic means of screening physical fitness in large participant samples because this method is quicker and cheaper than objective testing. Yet, previous studies have reported equivocal validity to reports of self-perceived fitness. A hybrid self-report variant is the use of self-administered/reported objective measurement. We sought to investigate the relative validity of this variant method compared to self-perception reports. In total 26,452 young Norwegian men and women participated in this study. We collected data during obligatory selection for military conscript service. Approximately half of the participants were asked to rate their endurance level on a five-point Likert scale in an online questionnaire. The other half performed a self-administered 3000 m run and reported the result online. Within 18 months, all participants completed an objective maximal treadmill test at a conscript selection center. We used Spearman correlations (r_s) and analyses of variance (ANOVAs) to investigate the relationships between these two self-report methods and the observed objective treadmill performance. Self-perceived and self-tested endurance were both identically correlated with the other-observed treadmill run for men (r_s = 0.59; p < .001) and for women (r_s = 0.50, p < .001); and ANOVAs revealed significant effects of self-perceived and self-tested endurance on treadmill run time, with higher self-reported endurance related to higher treadmill run time. In conclusion, self-perceived and self-tested endurance produced the same correlation coefficients with objectively measured treadmill run time. While there was a moderate relationship between self-reported and objectively measured endurance at the group level, there was substantial individual measurement error that should be considered for individual reports.