Quadriceps strength in intensive care unit survivors: Variability and influence of preadmission physical activity

Background: Muscle weakness is common in patients who survive a stay in the intensive care unit (ICU). Quadriceps strength (QS) measurement allows evaluation of lower limb performances that are associated with mobility outcomes.

Objectives: The objective of the study was to characterise the range of QS in ICU survivors (ICUS) during their short-term evolution, by comparing them with surgical patients without critical illness and with healthy participants. The secondary aim was to explore whether physical activity before ICU admission influenced QS during that trajectory.

Methods: Patients with length of ICU stay ≥2 days, adults scheduled for elective colorectal surgery, and young healthy volunteers were included. Maximal isometric QS was assessed using a handheld dynamometer and a previously validated standardised protocol. The dominant leg was tested in the supine position. ICUSs were tested in the ICU and 1 month after ICU discharge, while surgical patients were tested before and on the day after surgery, as well as 1 month after discharge. Healthy patients were tested once only. Patients were classified as physically inactive or active before admission from the self-report.

Results: Thirty-eight, 32, and 34 participants were included in the ICU, surgical, and healthy groups, respectively. Demographic data were similar in the ICUS and surgical groups. In the ICU, QS was lower in the ICU group than in the surgical and healthy groups (3.01 [1.88-3.48], 3.38 [2.84-4.37], and 5.5 [4.75-6.05] N/kg, respectively). QS did not significantly improve 1 month after ICU discharge, excepted in survivors who were previously physically active (22/38, 56%): the difference between the two time points was -6.6 [-27.1 to -1.7]% vs 20.4 [-3.4 to 43.3]%, respectively, in physically inactive and active patients (p = 0.002).

Conclusions: Patients who survived an ICU stay were weaker than surgical patients. However, a huge QS heterogeneity was observed among them. Their QS did not improve during the month after ICU discharge. Physically inactive patients should be early identified as at risk of poorer recovery.