A low-cost Mr compatible ergometer to assess post-exercise phosphocreatine recovery kinetics
To develop a low-cost pedal ergometer compatible with ultrahigh (7 T) field MR systems to reliably quantify metabolic parameters in human lower leg muscle using phosphorus magnetic resonance spectroscopy.
Materials and methods
We constructed an MR compatible ergometer using commercially available materials and elastic bands that provide resistance to movement. We recruited ten healthy subjects (eight men and two women, mean age ± standard deviation: 32.8 ± 6.0 years, BMI: 24.1 ± 3.9 kg/m2). All subjects were scanned on a 7 T whole-body magnet. Each subject was scanned on two visits and performed a 90 s plantar flexion exercise at 40% maximum voluntary contraction during each scan. During the first visit, each subject performed the exercise twice in order for us to estimate the intra-exam repeatability, and once during the second visit in order to estimate the inter-exam repeatability of the time constant of phosphocreatine recovery kinetics. We assessed the intra and inter-exam reliability in terms of the within-subject coefficient of variation (CV).
We acquired reliable measurements of PCr recovery kinetics with an intra- and inter-exam CV of 7.9% and 5.7%, respectively.
We constructed a low-cost pedal ergometer compatible with ultrahigh (7 T) field MR systems, which allowed us to quantify reliably PCr recovery kinetics in lower leg muscle using 31P-MRS.
KeywordsPhosphorus Human skeletal muscle Exercise Magnetic resonance spectroscopy
The authors thank Cornel Stefanescu for help with ergometer construction. This study was supported by NIH grants RO1 DK106292, and R01 AR060238, and was performed under the rubric of the Center of Advanced Imaging Innovation and Research (CAI2R), a NIBIB Biomedical Technology Resource Center (NIH P41 EB017183).
Compliance with ethical standards
Conflict of interest
The authors declare that they have no conflict of interest.
All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards.
Informed consent was obtained from all individual participants included in the study.
- 5.Fiedler GB, Schmid AI, Goluch S, Schewzow K, Laistler E, Niess F, Unger E, Wolzt M, Mirzahosseini A, Kemp GJ, Moser E, Meyerspeer M (2016) Skeletal muscle ATP synthesis and cellular H + handling measured by localized 31P-MRS during exercise and recovery. Sci Rep 6:32037CrossRefPubMedPubMedCentralGoogle Scholar
- 6.Kemp GJ, Crowe AV, Anijeet HK, Gong QY, Bimson WE, Frostick SP, Bone JM, Bell GM, Roberts JN (2004) Abnormal mitochondrial function and muscle wasting, but normal contractile efficiency, in haemodialysed patients studied non-invasively in vivo. Nephrol Dial Transplant 19(6):1520–1527CrossRefPubMedGoogle Scholar
- 22.Diekman EF, Visser G, Schmitz JPJ, Nievelstein RAJ, De Sain-van Der Velden M, Wardrop M, Van der Pol WL, van Riel NAW, Takken T, Jeneson JAL, Houten SM (2016) Altered energetics of exercise explain risk of rhabdomyolysis in very long-chain acyl-coa dehydrogenase deficiency. PLoS ONE 11(2):e0147818CrossRefPubMedPubMedCentralGoogle Scholar
- 27.Greiner A, Esterhammer R, Messner H, Biebl M, Mühlthaler H, Fraedrich G, Jaschke WR, Schocke MFH (2006) High-energy phosphate metabolism during incremental calf exercise in patients with unilaterally symptomatic peripheral arterial disease measured by phosphor 31 magnetic resonance spectroscopy. J Vasc Surg 43(5):978–986CrossRefPubMedGoogle Scholar
- 32.Šedivý P, Kipfelsberger MC, Dezortová M, Krššák M, Drobný M, Chmelík M, Rydlo J, Trattnig S, Hájek M, Valkovič L (2015) Dynamic 31P MR spectroscopy of plantar flexion: influence of ergometer design, magnetic field strength (3 and 7 T), and RF-coil design. Med Phys 42(4):1678–1689CrossRefPubMedGoogle Scholar
- 38.van den Broek NM, De Feyter HM, de Graaf L, Nicolay K, Prompers JJ (2007) Intersubject differences in the effect of acidosis on phosphocreatine recovery kinetics in muscle after exercise are due to differences in proton efflux rates. Am J Physiol Cell Physiol 293(1):C228–C237CrossRefPubMedGoogle Scholar
- 44.Schmid AI, Meyerspeer M, Robinson SD, Goluch S, Wolzt M, Fiedler GB, Bogner W, Laistler E, Krššák M, Moser E, Trattnig S, Valkovič L (2015) Dynamic PCr and pH imaging of human calf muscles during exercise and recovery using 31P gradient-Echo MRI at 7 Tesla. Magn Reson Med 75(6):2324–2331CrossRefPubMedGoogle Scholar