How Muscle Signals and Strength Chart the Path Out of ICU Weakness

nature.com June 29, 2026

This single-center observational study evaluated the utility of combining handgrip strength (HGS) and surface electromyography (sEMG) to objectively monitor neuromuscular function and early rehabilitation in intensive care unit (ICU) patients. Intensive care unit-acquired weakness (ICU-AW) is a frequent and debilitating consequence of critical illness that imposes severe functional limitations on survivors.

To investigate better tracking methods, researchers assessed 57 ICU patients who met the criteria for early rehabilitation. The team utilized bilateral sEMG parameters and HGS measurements, subsequently categorizing the participants into four distinct functional mobility levels.

The study revealed notable, sex-specific variations in muscle activity and functional achievement. In male patients, HGS significantly correlated with the contraction-phase sEMG activity of key muscle groups, including the biceps brachii, flexor digitorum superficialis, and rectus femoris.

Furthermore, men who advanced to the level of marching in place exhibited higher contraction-phase sEMG values in their forearms and thighs, likely reflecting the physical demands of upper-limb-assisted standing and core stabilization during vertical movement. In contrast, no significant HGS-sEMG correlations were found in women, though a distinct difference was noted in left-sided rectus femoris activity during contraction among those who achieved higher mobility.

Ultimately, the lack of significant correlations in female patients was attributed to the smaller sample size of the female subgroup, which limited statistical power. Despite this limitation, the study concludes that the paired assessment of handgrip strength and surface electromyography provides valuable, complementary information on neuromuscular function.

By bridging the gap between raw muscle electrical activity and practical physical force, this dual-monitoring approach offers a promising tool for tailoring and optimizing early rehabilitation protocols for critically ill patients.