BACKGROUND: During and after exercise, dynamic 31 P MR parameters are typically measured using an MR-compatible ergometer. Self-built equipment for local condition can be constructed where possible. PURPOSE: To develop a pedal resistance ergometer with rocker arm based on a system that combines electric weight displacement, visual self-monitoring, and exercise triggering. The repeatability and reproducibility were tested. METHODS: The hardware and software for the ergometer were constructed from commercial components in a home laboratory. Twelve volunteers participated in the testing of the ergometer. RESULTS: A fully automated ergometer system was developed, allowing the pedal resistance to be adjusted during the examination. The system includes a self-monitoring and triggering mechanism that enables both the operator and subject to monitor pedal frequency and force. The operator can modify the pedal resistance as desired during the exercise. This self-monitoring solution is simple and cost-effective, requiring only a commercial potentiometer, an Arduino converter, and a conventional video projector with a personal computer (PC). Additionally, all system components are located outside the magnetic resonance (MR) room, avoiding interference with the MR system. Results of several test of the reproducibility/repeatability of power at three pedal resistance values (15%, 24%, 25% maximal voluntary force) were expressed both as a coefficient of variation ranging from 6% to 3.1% and as an intraclass correlation of coefficient ranging from 0.96 to 0.99. Similar values were also found for other dynamic parameters of 31 P MR spectroscopy. These findings are similar to published data obtained on different types of ergometers. CONCLUSIONS: Based on more than 1 year of usage, the ergometer proved successful in handling stationary and variable loads, and can be easily operated by a single user.

Department of Medical Technology and Investments Institute for Clinical and Experimental Medicine Prague Czech Republic

ICAR Prague Czech Republic

Information Technology Division Institute for Clinical and Experimental Medicine Prague Czech Republic

MR Unit Department of Diagnostic and Interventional Radiology Institute for Clinical and Experimental Medicine Prague Czech Republic

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Meyerspeer M, Boesch C, Cameron D, et al. 31P magnetic resonance spectroscopy in skeletal muscle: experts’ consensus recommendations. NMR Biomed. 2020;34(5):e4246. doi:10.1002/nbm.4246

Šedivý P, Kipfelsberger MC, Dezortová M, et al. Dynamic 31P MR spectroscopy of plantar flexion: influence of ergometer design, magnetic field strength (3 and 7 T), and RF-coil design. Med Phys. 2015;42(4):1678-1689. doi:10.1118/1.4914448

Valkovič L, Chmelík M, Krššák M. In-vivo 31P-MRS of skeletal muscle and liver: a way for non-invasive assessment of their metabolism. Anal Biochem. 2017;529:193-215. doi:10.1016/j.ab.2017.01.018

Kemp GJ, Ahmad RE, Nicolay K, Prompers JJ. Quantification of skeletal muscle mitochondrial function by 31P magnetic resonance spectroscopy techniques: a quantitative review. Acta Physiol (Oxf). 2015;213(1):107-144. doi:10.1111/apha.12307

Hoff E, Brechtel L, Strube P, et al. Noninvasive monitoring of training induced muscle adaptation with 31P-MRS: fibre type shifts correlate with metabolic changes. Biomed Res Int. 2013;2013:417901. doi:10.1155/2013/417901

Sedivy P, Dezortova M, Rydlo J, et al. MR compatible ergometers for dynamic 31P MRS. J Appl Biomed. 2019;17:91-98. doi:10.32725/jab.2019.006

IKEM. Examination of the calf muscle using dynamic 31P MR spectroscopy. Accessed August 30, 2023. https://mrs.ikem.cz/en/galerie/videa

Kemp GJ, Meyerspeer M, Moser E. Absolute quantification of phosphorus metabolitconcentrations in human muscle in vivo by 31P MRS: a quantitative review. NMR Biomed. 2007;20(6):555-565. doi:10.1002/nbm.1192

Shrout PE, Fleiss JL. Intraclass correlations: uses in assessing rater reliability. Psychol Bull. 1979;86(2):420-428. doi:10.1037/0033-2909.86.2.420

Weiss K, Schär M, Panjrath GS, et al. Fatigability, exercise intolerance, and abnormal skeletal muscle energetics in heart failure. Circ Heart Fail. 2017;10(7):e004129. doi:10.1161/CIRCHEARTFAILURE.117.004129

Naimon ND, Walczyk J, Babb JS, et al. A low-cost MR compatible ergometer to assess post-exercise phosphocreatine recovery kinetics. MAGMA. 2017;30(3):281-289. doi:10.1007/s10334-016-0605-9