Maximal oxygen consumption and oxygen uptake efficiency in adolescent males

The oxygen uptake efficiency slope does not accurately predict V ˙ O2peak of children - the Arkansas Active Kids study

Background

Cardiorespiratory fitness (CRF) is a vital indicator of health. However, accurately measuring peak oxygen consumption (V ˙ O2peak) to determine CRF in children can be challenging. The oxygen uptake efficiency slope (OUES) has been proposed as an alternative metric for predictingV ˙ O2peak in children, but its accuracy and agreement with measuredV ˙ O2peak remain unclear.

Methods

A post hoc analysis was conducted in 94 children (ages 7-10 years) who completed an incremental cycle ergometer test to measureV ˙ O2peak. Body composition (Dual-energy X-ray absorptiometry) was measured, and fat mass index (FMI, kg/m2) and fat-free mass index (FFMI, kg/m2) were calculated. OUES was determined using all respiratory data (OUES100%) collected during the cycle ergometer test and using data only up to 60% of heart rate reserve (OUES60%HRR). Regression equations to predictV ˙ O2peak (Pred-V ˙ O2peak) were derived from simple and multiple linear regression analysis. Bland-Altman analysis assessed the level of agreement between Pred-V ˙ O2peak and measuredV ˙ O2peak.

Results

OUES60%HRR (β = 0.46, p < 0.0001), age (β = 56.0, p = 0.0004), White race (β = 173.3, p < 0.0003), FFMI (β = 0.98.6, p < 0.000), and FMI (β = -0.40.8, p < 0.000) were retained in the final model. The difference between measuredV ˙ O2peak and Pred-V ˙ O2peak was not different from zero (p = 0.999). There was a positive association between the difference of measuredV ˙ O2peak and Pred-V ˙ O2peak and the average of the two methods (β = 0.79, p = 0.0028).

Conclusion

There was no mean bias between measuredV ˙ O2peak and Pred-V ˙ O2peak. However, magnitude bias was present even after considering other significant predictors ofV ˙ O2peak (FMI, FFMI, race, and age) in the regression equation. Caution is advised when using OUES to predictV ˙ O2peak in children.

Oxygen uptake efficiency plateau is unaffected by fitness level - the NOODLE study

BACKGROUND

Endurance athletes (EA) are an emerging population of focus for cardiovascular health. The oxygen uptake efficiency plateau (OUEP) is the levelling-off period of ratio between oxygen uptake (VO2) and ventilation (VE). In the cohort of EA, we externally validated prediction models for OUEP and derived with internal validation a new equation.

METHODS

140 EA underwent a medical assessment and maximal cycling cardiopulmonary exercise test. Participants were 55% male (N = 77, age = 21.4 ± 4.8 years, BMI = 22.6 ± 1.7 kg·m- 2, peak VO2 = 4.40 ± 0.64 L·min- 1) and 45% female (N = 63, age = 23.4 ± 4.3 years, BMI = 22.1 ± 1.6 kg·m- 2, peak VO2 = 3.21 ± 0.48 L·min- 1). OUEP was defined as the highest 90-second continuous value of the ratio between VO2 and VE. We used the multivariable stepwise linear regression to develop a new prediction equation for OUEP.

RESULTS

OUEP was 44.2 ± 4.2 mL·L- 1 and 41.0 ± 4.8 mL·L- 1 for males and females, respectively. In external validation, OUEP was comparable to directly measured and did not differ significantly. The prediction error for males was - 0.42 mL·L- 1 (0.94%, p = 0.39), and for females was + 0.33 mL·L- 1 (0.81%, p = 0.59). The developed new prediction equation was: 61.37-0.12·height (in cm) + 5.08 (for males). The developed model outperformed the previous. However, the equation explained up to 12.9% of the variance (R = 0.377, R2 = 0.129, RMSE = 4.39 mL·L- 1).

CONCLUSION

OUEP is a stable and transferable cardiorespiratory index. OUEP is minimally affected by fitness level and demographic factors. The predicted OUEP provided promising but limited accuracy among EA. The derived new model is tailored for EA. OUEP could be used to stratify the cardiorespiratory response to exercise and guide training.

Efficacy of Lactococcus lactis subsp. lactis LY-66 and Lactobacillus plantarum PL-02 in Enhancing Explosive Strength and Endurance: A Randomized, Double-Blinded Clinical Trial

Probiotics are posited to enhance exercise performance by influencing muscle protein synthesis, augmenting glycogen storage, and reducing inflammation. This double-blind study randomized 88 participants to receive a six-week intervention with either a placebo, Lactococcus lactis subsp. lactis LY-66, Lactobacillus plantarum PL-02, or a combination of both strains, combined with a structured exercise training program. We assessed changes in maximal oxygen consumption (VO2max), exercise performance, and gut microbiota composition before and after the intervention. Further analyses were conducted to evaluate the impact of probiotics on exercise-induced muscle damage (EIMD), muscle integrity, and inflammatory markers in the blood, 24 and 48 h post-intervention. The results demonstrated that all probiotic groups exhibited significant enhancements in exercise performance and attenuation of muscle strength decline post-exercise exhaustion (p < 0.05). Notably, PL-02 intake significantly increased muscle mass, whereas LY-66 and the combination therapy significantly reduced body fat percentage (p < 0.05). Analysis of intestinal microbiota revealed an increase in beneficial bacteria, especially a significant rise in Akkermansia muciniphila following supplementation with PL-02 and LY-66 (p < 0.05). Overall, the combination of exercise training and supplementation with PL-02, LY-66, and their combination improved muscle strength, explosiveness, and endurance performance, and had beneficial effects on body composition and gastrointestinal health, as evidenced by data obtained from non-athlete participants.

Cardiorespiratory optimal point as a submaximal evaluation tool in endurance athletes: An exploratory study

Introduction: The cardiorespiratory optimal point (COP) represents the lowest minute ventilation to oxygen consumption ratio (VE/VO2) and can be estimated during a CPET at submaximal intensity when an exercise test until volitional fatigue is not always advisable (i.e., a conflict zone where you cannot be confident of the security because near-competition, off-season, among other). COP's physiological components have not been wholly described yet. Therefore, this study seeks to identify the determinants of COP in highly trained athletes and its influence on maximum and sub-maximum variables during CPET through principal c omponent analysis (PCA) (explains the dataset's variance). Methods: Female (n = 9; age, 17.4 ± 3.1 y; maximal VO2 [VO2max]), 46.2 ± 5.9 mL/kg/min) and male (n = 24; age, 19.7 ± 4.0 y; VO2max, 56.1 ± 7.6 mL/kg/min) athletes performed a CPET to determine the COP, ventilatory threshold 1 (VT1) and 2 (VT2), and VO2max. The PCA was used to determine the relationship between variables and COP, explaining their variance. Results: Our data revealed that females and males displayed different COP values. Indeed, males showed a significant diminished COP compared to the female group (22.6 ± 2.9 vs. 27.2 ±3.4 VE/VO2, respectively); nevertheless, COP was allocated before VT1 in both groups. Discussion: PC analysis revealed that the COP variance was mainly explained (75.6%) by PC1 (expired CO₂ at VO2max) and PC2 (VE at VT2), possibly influencing cardiorespiratory efficiency at VO2max and VT2. Our data suggest that COP could be used as a submaximal index to monitor and assess cardiorespiratory system efficiency in endurance athletes. The COP could be particularly useful during the offseason and competitive periods and the return to the sports continuum.

Improved Oxygen Uptake Efficiency Parameters Are Not Correlated with VO2peak or Running Economy and Are Not Affected by Omega-3 Fatty Acid Supplementation in Endurance Runners

Peak oxygen uptake (VO_2peak) is one of the most reliable parameters of exercise capacity; however, maximum effort is required to achieve this. Therefore, alternative, and repeatable submaximal parameters, such as running economy (RE), are needed. Thus, we evaluated the suitability of oxygen uptake efficiency (OUE), oxygen uptake efficiency plateau (OUEP) and oxygen uptake efficiency at the ventilatory anaerobic threshold (OUE@VAT) as alternatives for VO_2peak and RE. Moreover, we evaluated how these parameters are affected by endurance training and supplementation with omega-3 fatty acids. A total of 26 amateur male runners completed a 12-week endurance program combined with omega-3 fatty acid supplementation or medium-chain triglycerides as a placebo. Before and after the intervention, the participants were subjected to a treadmill test to determine VO_2peak, RE, OUE, OUEP and OUE@VAT. Blood was collected at the same timepoints to determine eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) in erythrocytes. OUE correlated moderately or weakly with VO_2peak (R² = 0.338, p = 0.002) and (R² = 0.226, p = 0.014) before and after the intervention, respectively. There was a weak or no correlation between OUEP, OUE@VAT, VO_2peak and RE despite steeper OUE, increased OUEP and OUE@VAT values in all participants. OUE parameters cannot be treated as alternative parameters for VO_2peak or RE and did not show changes following supplementation with omega-3 fatty acids in male amateur endurance runners.

Oxygen uptake efficiency slope in healthy normal weight young males: an applicable framework for calculation and interpretation

Background

The oxygen uptake efficiency slope (OUES) is considered a reliable indicator of cardiorespiratory fitness in young and clinical populations who cannot achieve maximal effort during a graded exercise test. However, OUES accuracy depends on the data points used for its calculation and it is still not clear if the submaximal OUES can accurately assess CRF in healthy young males.

Objective

We investigated the association between peak oxygen uptake and peak and submaximal OUES, and the agreement between submaximal OUES and peak OUES in male adolescents and young adults.

Methods

In this cross-sectional, observational study, fifty normal weight healthy participants (age 14-22 years, peak oxygen uptake 43.8 ± 7.3 mL·min^-1·kg^-1) performed a graded exercise test on a cycle ergometer and pulmonary gas exchange was assessed using breath-by-breath analysis. Peak oxygen uptake, and oxygen consumption at the aerobic and at the anaerobic threshold were determined as the 30-s average of the oxygen consumption values. Peak OUES (up to peak) and submaximal OUES (up to the aerobic and anaerobic thresholds) were calculated from the logarithmic relation between oxygen consumption and pulmonary ventilation.

Results

Very strong correlations were observed between peak oxygen uptake and peak OUES (r = 0.80-0.88) while fair-to-very strong correlations were observed between the peak oxygen uptake and the two submaximal OUES (r = 0.32-0.81). The level of agreement between peak OUES and OUES up to the anaerobic threshold (r = 0.89-0.93; Typical percentage error 6%; Intraclass correlation coefficient = 0.89-0.93) was greater than the one between the peak oxygen uptake with OUES up to the aerobic threshold (r = 0.39-0.56; Typical percentage error 15%; Intraclass correlation coefficient = 0.38-0.56).

Conclusions

. The peak OUES is a better indicator of aerobic fitness than the OUES up to the anaerobic threshold in healthy, young males. The OUES up to the anaerobic threshold is a valid alternative to peak OUES.

Oxygen Supply System Management in an Overweight Adult after 12 Months in Antarctica-Study Case

The aim of the study was to try to determine the functional state of the respiratory system, i.e., selected parameters and indicators of physiological systems responsible for the supply of oxygen at all stages of its delivery in people as their body weight increases from normal weight to overweight. The studies include an analysis of test results of functional respiratory system state (FSD) indicators of a 30-year-old and 170-cm tall man. Measurements of FSD were conducted two times: the first time before an expedition to Antarctica at 70 kg (normal body weight); the next measurements were taken a year later, after coming back from the expedition, at 82 kg (overweight). When analyzing the functional respiratory system state in terms of the effect of overweight it was found that the maintenance of the oxygen homeostasis in those conditions occurred at the level of a compensated hypoxic state. That is why the decision to engage in physical activity can be made only if we are sure that significant destructive additive effects of both types of hypoxic influences (from excessive body weight and from the physical activity) are not overlapping.