Is respiratory exchange ratio an alternative to estimate anaerobic threshold in trained runners?

Diefenthaeler, Fernando; Sakugawa, Raphael Luiz; Dellagrana, Rodolfo André; Follmer, Bruno; Lemos, Elisa Cristina; Campos, Wagner de

doi:10.5007/1980-0037.2017v19n1p108

Cited by 4 publications

(6 citation statements)

References 20 publications

(45 reference statements)

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“…Notably, heart rate (HR), adapted rating of perceived exertion (RPE) Borg scale 1–10 ( DaSilva-Grigoletto et al, 2013 ) and Visual Analogue pain Scale (VAS) were controlled every 1-min 30-s along the test. The protocol aimed to reach the second ventilatory threshold (VT 2 ), determined by at least two of the three following criteria: RER >1.1 ( Diefenthaeler et al, 2017 ), peak of HR (HR peak ) >80% HR max ( Karapetian et al, 2008 ), and/or RPE >6 ( Seiler and Kjerland, 2006 ; Diefenthaeler et al, 2017 ). Whenever a VAS>5 and/or oxygen saturation (SpO 2 %) <92%, the women were invited to end the test to ensure a comfortable and secure testing session.…”

Section: Methodsmentioning

confidence: 99%

Metabolic Flexibility and Mechanical Efficiency in Women Over-60

et al. 2022

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Purpose: Aging deteriorates metabolic flexibility (MF). Moreover, recent studies show that glycolysis is barely increased despite impoverished lipid metabolism, in addition to increased relevance of muscle power in older adults. This study aims to analyze MF, i.e., fat and carbohydrates oxidation rates (FATox and CHOox), and the point of maximal fat oxidation (MFO), in a group of active women over-60. It also aims to delve into the role of power production and mechanical efficiency regarding MF. This will help to decipher their metabolic behavior in response to increasing intensity.Methods: Twenty-nine women (66.13 ± 5.62 years) performed a submaximal graded cycling test, increasing 10 W each 3-min15-s, from 30 W to the second ventilatory threshold (VT2). Muscle power was adjusted with a Saris-H3 roller, together with a continuous gas analysis by indirect calorimetry (Cosmed K4b2). Pre and post-test blood lactate (BLa) samples were included. Frayn’s equations, MFO and CHOoxpeak (mg/min/kg FFM) were considered for MF analysis (accounting for average VO2 and VCO2 in each last 60-s), whilst delta and gross efficiencies (DE%, GE%), and exercise economy (EC), were added for Mechanical Efficiency. Mean comparisons regarding intensities 60, 80 and 100% at VT2, completed the study together with correlation analysis among the main variables.Results: MFO and CHOoxpeak were small (6.35 ± 3.59 and 72.79 ± 34.76 g/min/kgFFM respectively) for a reduced muscle power (78.21 ± 15.84 W). Notwithstanding, GE% and EC increased significantly (p < 0.01) with exercise intensity. Importantly, coefficients of variation were very large confirming heterogeneity. Whilst muscle power outcomes correlated significantly (p < 0.01) with MFO (r = 0.66) and age (r = −0.62), these latter failed to be associated. Only GE% correlated to CHOoxpeak (r = −0.61, p < 0.01) regarding mechanical efficiency.Conclusions: Despite being active, women over-60 confirmed impaired substrates switching in response to exercise, from both FAT and CHO pathways. This limits their power production affecting exercise capacity. Our data suggest that decreased power with age has a key role above age per se in this metabolic inflexibility. Vice versa, increasing power seems to protect from mitochondrial dysfunction with aging. New studies will confirm if this higher efficiency when coming close to VT2, where GE is the more informative variable, might be a protective compensatory mechanism.

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Section: Methodsmentioning

confidence: 99%

Metabolic Flexibility and Mechanical Efficiency in Women Over-60

et al. 2022

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“…RER > 1.0 was used to estimate the AT. 1,3 The normality of the data was tested using a Shapiro-Wilk test. A one-tailed Wilcoxon Signed Rank test was used to assess the differences in NIRS data between each exercise stage.…”

Section: Discussionmentioning

confidence: 99%

“…The anaerobic threshold (AT), also known as the lactate threshold, is a point during exercise where the production of lactate in the blood is equal to the rate of blood lactate removal. 1 Continuing to exercise past the AT can significantly impact cardiopulmonary performance during exercise. 2 The associated accumulation of blood lactate can contribute to impaired muscle contraction, hyperventilation, and oxygen delivery, which can negatively impact athletic performance.…”

Section: Introductionmentioning

confidence: 99%

Predicting muscle anaerobic threshold by using a wearable optical sensor during exercise

Mah

Nourizadeh²,

Wyss³

et al. 2023

Biophotonics in Exercise Science, Sports Medicine, Health Monitoring Technologies, and Wearables IV

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Background:The anaerobic threshold (AT) is a point during intense exercise that can be used to predict muscular fatigue. Determining the AT non-invasively helps to adjust exercise intensity and prevent overuse injuries. Near-infrared spectroscopy (NIRS) is an optical technology that can provide real-time information about muscle oxidative metabolism. The objective of this pilot study was to investigate the relationship between NIRS parameters of muscle oxygenation and traditional measures of exercise monitoring, such as heart rate and relative body oxygen consumption (VO2).Methods: Healthy adults with moderate to high fitness levels participated in an incremental exercise protocol on a stationary bicycle. NIRS parameters were compared to ventilatory VO2 using a metabolic cart. Respiratory Exchange Ratio (RER) > 1.0 was used as a proxy for determining the AT. NIRS data were collected from the primary locomotor muscle (vastus lateralis -VL) and a control muscle (deltoid) using two wearable NIRS sensors. Heart rate data were collected by a wearable ECG sensor. Results:The NIRS data showed a significant decline in VL muscle oxygenated hemoglobin (O2Hb) concentration (p<0.05) at one exercise stage after the AT was identified. Muscle O2Hb did not show a significant decrease in the deltoid at the AT. Furthermore, there were no noticeable changes in heart rate at the AT. Conclusion:Our results indicate that a wearable NIRS sensor can predict the AT in exercising muscles and may provide a localized measure of muscular fatigue during exercise.

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“…Other studies have linked VT2 to a RER of 1.00. Long known that "additional" CO 2 is released above this point as a product of the bicarbonate buffering system associated with lactate accumulation [10].…”

Section: Original Articlementioning

confidence: 99%

“…We describe a regression for RER versus "t" and determine at which measurement number its value remains permanently above 1.00 (Figure 2). At this point we determine the RCP [10].…”

Section: Determination Of Ant By Rcpmentioning

confidence: 99%

Comparison between determination of second anaerobic threshold by respiratory compensating point and X-method in rowers

Stefanov¹

2022

ppcs

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Background and Study Aim. The aim of this study is to verify the X-method for determining the second anaerobic threshold in rowers.Material and Methods. Twelve male athletes from the national rowing team of Bulgaria were tested. Participants performed a one-time graded incremental exercise test to exhaustion on a rowing ergometer. The workload were conducted on rowing ergometer system Concept 2, and spirometry system Clark C5. We obtained ventilatory indices, intensity and heart rate bred-by-bred for each participant, for each test stage. The anaerobic threshold was determined by two methods: 1) by the localization of the respiratory compensation point visually, after polynomial regression analysis of the trends for the dynamics of the ventilatory variables related to time and 2) by the X-method using the change in the ratio between heart rate and pulmonary ventilation. We compared the heart rate corresponding to the anaerobic threshold determined by both methods.Results. We found similar values for heart rate at the respiratory compensation point and the anaerobic threshold determined by the X-method for each of the investigated. The Shapiro-Wilk test showed a normal distribution of the two samples with a significance level of α = 0.05. Thus, the t-test for two paired samples showed a p-value of 0.202 at α = 0.05. We found a correlation coefficient r = 0.973 between the heart rate at the anaerobic threshold (determined by X-method) and the heart rate at the anaerobic threshold (detected at the respiratory compensation point). The Blant-Altman analysis showed that 95% of the points in the scatter plot lie within the confidence interval.Conclusions. The two methods give similar results and can be applied alternatively in the investigation of rowers in the age group 18.3 ± 1.07 years. The X-method always gives a reliable intersection point, which in our studies is close to the second anaerobic threshold. Comparative studies are also needed in other contingents for the wider use of the X-method.

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Is respiratory exchange ratio an alternative to estimate anaerobic threshold in trained runners?

Cited by 4 publications

References 20 publications

Metabolic Flexibility and Mechanical Efficiency in Women Over-60

Metabolic Flexibility and Mechanical Efficiency in Women Over-60

Predicting muscle anaerobic threshold by using a wearable optical sensor during exercise

Comparison between determination of second anaerobic threshold by respiratory compensating point and X-method in rowers

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