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Purpose. Maintaining balance during static standing postures requires the coordination of many neuromuscular mechanisms. The role of the intrinsic and extrinsic foot muscles in this paradigm has yet to be clearly defined. The purpose of this study was to explore foot muscle activation during static phases on common weight-bearing tasks of varying loads and balance demands. Methods. Twenty healthy young adults performed 6 standing postures (single-limb and double-limb stand, squat, and heel raise) with one foot on a force plate. Muscle activity was recorded from the abductor hallucis, flexor hallucis longus and brevis, and tibialis posterior using intramuscular electrodes; surface electrodes were used to record activity from the peroneus longus and tibialis anterior. Two-way repeated measures ANOVA (2 loading conditions × 3 postures) were run to compare muscle activation and center of pressure velocity. Results. Intrinsic foot muscle activity increased as loading and postural demand increased; however, the specific effects varied for each of the extrinsic foot muscles. Conclusions. These results suggest that the intrinsic foot muscles play an important role in maintaining static balance. Strengthening intrinsic and extrinsic foot muscles may help increase stability in people who have weak toe flexors or who suffer from a variety of foot pathologies.

International audience; During this work, an original study of the CO2 and SO2 competitive gas absorption in three superbase ionic liquids (ILs), namely, trihexyltetradecylphosphonium 1,2,4-triazolide ([P66614][124Triz]), and trihexyltetradecylphoshonium benzimidazolide ([P66614][Benzim]), is reported for the first time. To initiate such a comprehensive study, the CO2 and SO2 mixed gas solubility in selected ILs was determined by using an original and accurate dynamic method coupled with mass spectrometry after several absorption and desorption cycles. This method has been validated by comparing the gravimetric uptake of CO2 with the mass spectrometry data using trihexyltetradecylphosphonium benzotriazolide, 1,2,4-triazolide, and benzimidazolide ILs and shown to be consistent within 10% in mole ratio units. Solubility results clearly show that the presence of SO2 in the gas stream decreases the CO2 capture capability of the investigated ILs. Furthermore, the viscosity, chemical analysis (water content and sulfur content), and spectroscopic data (1H NMR, 13C NMR, attenuated total reflectance-infrared, and X-ray photoelectron spectroscopy) changes before and after absorption–desorption of the gases were determined and depicted to truly understand the reaction mechanism that occurs in the liquid phase, highlighting a clear competition between the SO2 versus CO2 chemical reaction and selected superbase ILs.