Preserved anabolic skeletal muscle capacity in response to exercise and protein intake after critical illness.

In 30 seconds

This clinical trial compared skeletal muscle responses to resistance exercise plus protein intake in 20 intensive care unit (ICU) survivors, assessed 3 to 6 months after discharge, and 20 age- and sex-matched controls. Muscle protein synthesis was measured before and after the intervention. Survivors had a higher baseline synthesis rate but a smaller increase than controls (Δ 0.031 vs. Δ 0.040%/hour, p = 0.04); after the intervention, rates were similar (0.071%/hour vs. 0.070%/hour, p = 0.70). The findings indicate preserved capacity to reach similar post-intervention synthesis rates despite persistent muscle loss and weakness.

Key findings

• Baseline muscle protein synthesis was higher in ICU survivors than controls (0.041%/hour vs. 0.030%/hour, p = 0.009).
• The increase in synthesis was smaller in survivors (Δ 0.031 vs. Δ 0.040%/hour, p = 0.04), while post-intervention rates were similar (0.071%/hour vs. 0.070%/hour, p = 0.70).
• Survivors had lower quadriceps muscle thickness (p = 0.02) and handgrip strength (p = 0.04) than controls.
• The intervention increased anabolic signalling and altered autophagy and ubiquitin-proteasome pathway measures in both groups.

Why it matters

Persistent muscle loss and weakness after critical illness may reflect more than an inability to stimulate muscle protein synthesis. Despite a smaller increase from baseline, survivors reached post-intervention synthesis rates similar to controls. This mechanistic finding supports the potential relevance of combining exercise and protein intake in rehabilitation research, while not establishing the intervention’s effects on longer-term strength or functional recovery.

What to keep in mind

The study included 20 ICU survivors and assessed an acute muscle protein synthesis response; it does not establish longer-term effects on muscle mass, strength, or function.