Ultrasound for measurement of skeletal muscle mass quantity and muscle composition/architecture in critically ill patients: A scoping review on studies' aims, methods, and findings.

AIMS: This scoping review aimed to identify, explore, and map the objectives, methodological aspects, and results of studies that used ultrasound (US) to assess skeletal muscle (SM) in critically ill patients. METHODS: A scoping review was conducted according to the Joanna Briggs Institute's methodology. All studies that evaluated SM parameters from the US in patients admitted to the intensive care unit (ICU) were considered eligible. We categorized muscle thickness and cross-sectional area as parameters for assessing SM quantity, while echogenicity, fascicle length, and pennation angle analysis were used to evaluate muscle "quality" (composition/architecture). A literature search was conducted using four databases for articles published until December 2022. Independent reviewers selected the studies and extracted data. Descriptive statistics were calculated to present the results. RESULTS: A total of 107 studies were included, the majority of which were prospective cohort studies (59.8 %) conducted in general ICUs (49.5 %). The most frequent objective of the studies was to evaluate SM quantity depletion during the ICU stay (25.2 %), followed by determining whether a specific intervention would modify SM (21.5 %). Most studies performed serial SM evaluations (76.1 %). The rectus femoris muscle thickness was evaluated in most studies (67.9 %), followed by the rectus femoris cross-sectional area (54.3 %) and the vastus intermedius muscle thickness (40.2 %). The studies demonstrated the feasibility and reproducibility of US for SM evaluation, especially related to quantitative parameters. Most studies (70.3 %) reported significant SM quantity depletion during hospitalization. However, the accuracy of the US in measuring SM varied across the studies. CONCLUSIONS: The lack of detailed description and standardization in the protocols adopted by the studies included in this scoping review precludes the translation of the evidence related to US for SM assessment into clinical practice.

Can supplemental protein to low-protein containing meals superimpose on resistance-training muscle adaptations in older adults? A randomized clinical trial.

PURPOSE: To evaluate the effects of supplementing protein to the low-protein containing meals on selected parameters of muscle mass, strength, and functional capacity in older individuals undergoing resistance training. METHODS: Thirty-one male and female older individuals (60 to 80 years) were randomized into either a whey protein/WP (n = 15, 20 g at breakfast + 20 g at dinner) or placebo-maltodextrin/PL (n = 16, 20 g at breakfast + 20 g at dinner) group. Both groups underwent a supervised, progressive resistance training (2×/week) program for 12 weeks. Maximal isometric voluntary contraction (MIVC) of knee extensors, muscle thickness (MT) of knee extensors and elbow flexors, rectus femoris muscle quality (MQ), body composition (as measured by DXA) and functional capacity [as measured by 30-s sit-to-stand (30ss) and timed-up-and-go tests (TUG)] were evaluated at baseline and after the 12-week intervention. RESULTS: Knee extensor MIVC (WP ∆ = 11.9 ± 11.4% and PL ∆ = 12.9 ± 9.9%) was significantly increased over time, with no between-group differences (all p < 0.05 for main effect of time). Upper- and lower-limb MT were significantly increased over time, with no effect of supplementation (WP: ∆ = 7.0 ± 7.3%, PL: ∆ = 9.5 ± 10.3%; and WP: ∆ = 4.5 ± 5.8%, PL: ∆ = 14.7 ± 28.9%, respectively; all p = 0.001 for main effect of time, respectively). Total and upper-limb lean mass were significantly increased, irrespective of the dietary intervention (WP: ∆ = 0.2 ± 6.3%, PL: ∆ = 1.8 ± 2.9%; and WP: ∆ = 0.10 ± 0.03%, PL: ∆ = 0.15 ± 0.02%, respectively; all p < 0.05 for main effect of time). Main effects of time (all p < 0.05) were also found for 30SS and TUG (fast and usual speeds) (WP: ∆ = 18.2 ± 34.4%, PL: ∆ = 10.4 ± 16.9%; WP: ∆ = 5.4 ± 6.7%, PL: ∆ = 0.7 ± 6.0% and WP: ∆ = 3.3 ± 6.1%, PL: ∆ = 2.3 ± 5.2%, respectively). CONCLUSION: Supplementing additional whey protein to the lowest-protein containing meals (i.e., ~20 g at breakfast and ~20 g at dinner, daily) did not further augment resistance training-induced neuromuscular adaptations (i.e. muscle strength and mass) in healthy older individuals.