A Comparison of Methodological Approaches to Measuring Cycling Mechanical Efficiency

Matomäki, Pekka; Linnamo, Vesa; Kyröläinen, Heikki

doi:10.1186/s40798-019-0196-x

Cited by 11 publications

(16 citation statements)

References 43 publications

(91 reference statements)

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“…According to a review article, 26 the mean DE of 14 studies was 23.8 ± 2.6%. Similar DE (23.8%) was reported in another study with sport science students 27 . Given the reported results in these studies, it appears that COVID‐19 patients may have decreased mechanical efficiency compared with healthy people and about 20% could be a reference value for DE.…”

Section: Discussionsupporting

confidence: 84%

Severe loss of mechanical efficiency in COVID‐19 patients

Pleguezuelos

Carmen

Llorensi

et al. 2021

J cachexia sarcopenia muscle

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Background There is limited information about the impact of coronavirus disease (COVID‐19) on the muscular dysfunction, despite the generalized weakness and fatigue that patients report after overcoming the acute phase of the infection. This study aimed to detect impaired muscle efficiency by evaluating delta efficiency (DE) in patients with COVID‐19 compared with subjects with chronic obstructive pulmonary disease (COPD), ischaemic heart disease (IHD), and control group (CG). Methods A total of 60 participants were assigned to four experimental groups: COVID‐19, COPD, IHD, and CG ( n = 15 each group). Incremental exercise tests in a cycle ergometer were performed to obtain peak oxygen uptake (VO 2 peak). DE was obtained from the end of the first workload to the power output where the respiratory exchange ratio was 1. Results A lower DE was detected in patients with COVID‐19 and COPD compared with those in CG ( P ≤ 0.033). However, no significant differences were observed among the experimental groups with diseases ( P > 0.05). Lower VO 2 peak, peak ventilation, peak power output, and total exercise time were observed in the groups with diseases than in the CG ( P < 0.05). A higher VO 2 , ventilation, and power output were detected in the CG compared with those in the groups with diseases at the first and second ventilatory threshold ( P < 0.05). A higher power output was detected in the IHD group compared with those in the COVID‐19 and COPD groups ( P < 0.05) at the first and second ventilatory thresholds and when the respiratory exchange ratio was 1. A significant correlation ( P < 0.001) was found between the VO 2 peak and DE and between the peak power output and DE ( P < 0.001). Conclusions Patients with COVID‐19 showed marked mechanical inefficiency similar to that observed in COPD and IHD patients. Patients with COVID‐19 and COPD showed a significant decrease in power output compared to IHD during pedalling despite having similar response in VO 2 at each intensity. Resistance training should be considered during the early phase of rehabilitation.

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Section: Discussionsupporting

confidence: 84%

Severe loss of mechanical efficiency in COVID‐19 patients

Pleguezuelos

Carmen

Llorensi

et al. 2021

J cachexia sarcopenia muscle

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“…To conclude with the analysis of mechanical efficiency, GE% and DE% did not correlate between them at Power peak , as already noted in previous works ( Broskey et al, 2015 ). Whilst DE informs about the averaged mechanical efficiency of an isolated musculoskeletal system, that is, the test as a whole, GE expresses the mechanical efficiency in any segment of this test, considering the metabolic behavior in the segment as a whole body ( Matomäki et al, 2019 ). In addition to the above-mentioned limitation of DE in order to evaluate the short tests in these populations, this index displayed larger heterogeneity and has shown to be either sensible to the testing protocols ( De Koning et al, 2012 ).…”

Section: Discussionmentioning

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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“…From the indirect calorimetry data, energy expenditure and substrate oxidation rates were calculated using Weir's formula under the assumption of negligible protein oxidation ( 39 ). In addition, gross exercise efficiency (GEE) was calculated as (W ext /E tot ) and net exercise efficiency (NEE) was calculated as [W ext /(E tot - E rest )] ( 40 ) from the submaximal exercise indirect calorimetry data.…”

Section: Methodsmentioning

confidence: 99%

NAD+-Precursor Supplementation With L-Tryptophan, Nicotinic Acid, and Nicotinamide Does Not Affect Mitochondrial Function or Skeletal Muscle Function in Physically Compromised Older Adults

Connell

Grevendonk

Fealy

et al. 2021

The Journal of Nutrition

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Background Boosting NAD+ via supplementation with niacin equivalents has been proposed as a potential modality capable of promoting healthy aging and negating age-dependent declines of skeletal muscle mass and function. Objectives We investigated the efficacy of NAD+-precursor supplementation (tryptophan, nicotinic acid, and nicotinamide) on skeletal muscle mitochondrial function in physically compromised older adults. Methods A randomized, double-blind, controlled trial was conducted in 14 (female/male: 4/10) community-dwelling, older adults with impaired physical function [age, 72.9 ± 4.0 years; BMI, 25.2 ± 2.3 kg/m2]. Participants were supplemented with 207.5 mg niacin equivalents/day [intervention (INT)] and a control product (CON) that did not contain niacin equivalents, each for 32 days. The primary outcomes tested were mitochondrial oxidative capacity and exercise efficiency, analyzed by means of paired Student's t-tests. Secondary outcomes, such as NAD+ concentrations, were analyzed accordingly. Results Following supplementation, skeletal muscle NAD+ concentrations [7.5 ± 1.9 compared with 7.9 ± 1.6 AU, respectively] in INT compared with CON conditions were not significantly different compared to the control condition, whereas skeletal muscle methyl-nicotinamide levels were significantly higher under NAD+-precursor supplementation [INT, 0.098 ± 0.063 compared with CON, 0.025 ± 0.014; P = 0.001], suggesting an increased NAD+ metabolism. Conversely, neither ADP-stimulated [INT, 82.1 ± 19.0 compared with CON, 84.0 ± 19.2; P = 0.716] nor maximally uncoupled mitochondrial respiration [INT, 103.4 ± 30.7 compared with CON, 108.7 ± 33.4; P = 0.495] improved under NAD+-precursor supplementation, nor did net exercise efficiency during the submaximal cycling test [INT, 20.2 ± 2.77 compared with CON, 20.8 ± 2.88; P = 0.342]. Conclusions Our findings are consistent with previous findings on NAD+ efficacy in humans, and we show in community-dwelling, older adults with impaired physical function that NAD+-precursor supplementation through L-tryptophan, nicotinic acid, and nicotinamide does not improve mitochondrial or skeletal muscle function. This study was registered at clinicaltrials.gov as NCT03310034.

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A Comparison of Methodological Approaches to Measuring Cycling Mechanical Efficiency

Cited by 11 publications

References 43 publications

Severe loss of mechanical efficiency in COVID‐19 patients

Severe loss of mechanical efficiency in COVID‐19 patients

Metabolic Flexibility and Mechanical Efficiency in Women Over-60

NAD+-Precursor Supplementation With L-Tryptophan, Nicotinic Acid, and Nicotinamide Does Not Affect Mitochondrial Function or Skeletal Muscle Function in Physically Compromised Older Adults

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