. Author manuscript; available in PMC: 2018 Dec 1.

Published in final edited form as: Med Sci Sports Exerc. 2017 Dec;49(12):2404–2413. doi: 10.1249/MSS.0000000000001391

Table 1.

Intramuscular metabolite concentrations at task failure for high-intensity intermittent isometric single-leg knee-extensor exercise

	CTRL	FENT
[PCr] (mM)	4.3 ± 2.4	4.4 ± 2.5
[PCr] (%)	16.8 ± 8.9	16.1 ± 8.7
[Pi] (mM)	27.7 ± 7.0	37.5 ± 17.1^†
[H₂PO₄⁻] (mM)	17.3 ± 6.0	24.2 ± 12.3^†
pH	6.54 ± 0.14	6.51 ± 0.09
[ATP] (%)	82.6 ± 14.9	75.4 ± 16.8^†

Values are mean ± SD. Intramuscular metabolite concentrations were determined using phosphorous magnetic resonance spectroscopy in control (CTRL) and fentanyl (FENT) conditions. PCr, phosphocreatine; Pi, inorganic phosphate; H₂PO₄⁻, diprotonated Pi; ATP, adenosine triphosphate. PCr and ATP are presented as a percentage of baseline values.

^†

significantly different from CTRL.