Introduction: Protein ingestion during recovery from exercise has been reported to augment myofibrillar protein synthesis rates, without increasing muscle connective protein synthesis rates. It has been suggested that collagen protein may be effective in stimulating muscle connective protein synthesis. The present study assessed the capacity of both whey and collagen protein ingestion to stimulate postexercise myofibrillar and muscle connective protein synthesis rates. Methods: In a randomized, double-blind, parallel design, 45 young male ( n = 30) and female ( n = 15) recreational athletes (age, 25 ± 4 yr; body mass index, 24.1 ± 2.0 kg·m -2 ) were selected to receive primed continuous intravenous infusions with l -[ring- 13 C 6 ]-phenylalanine and l -[3,5- 2 H 2 ]-tyrosine. After a single session of resistance type exercise, subjects were randomly allocated to one of three groups ingesting either 30 g whey protein (WHEY, n = 15), 30 g collagen protein (COLL, n = 15) or a noncaloric placebo (PLA, n = 15). Blood and muscle biopsy samples were collected over a subsequent 5-h recovery period to assess both myofibrillar and muscle connective protein synthesis rates. Results: Protein ingestion increased circulating plasma amino acid concentrations ( P < 0.05). The postprandial rise in plasma leucine and essential amino acid concentrations was greater in WHEY compared with COLL, whereas plasma glycine and proline concentrations increased more in COLL compared with WHEY ( P < 0.05). Myofibrillar protein synthesis rates averaged 0.041 ± 0.010, 0.036 ± 0.010, and 0.032 ± 0.007%·h -1 in WHEY, COLL and PLA, respectively, with only WHEY resulting in higher rates when compared with PLA ( P < 0.05). Muscle connective protein synthesis rates averaged 0.072 ± 0.019, 0.068 ± 0.017, and 0.058 ± 0.018%·h -1 in WHEY, COLL, and PLA, respectively, with no significant differences between groups ( P = 0.09). Conclusions: Ingestion of whey protein during recovery from exercise increases myofibrillar protein synthesis rates. Neither collagen nor whey protein ingestion further increased muscle connective protein synthesis rates during the early stages of postexercise recovery in both male and female recreational athletes.
Background & aims: Low muscle mass and -quality on ICU admission, as assessed by muscle area and -density on CT-scanning at lumbar level 3 (L3), are associated with increased mortality. However, CT-scan analysis is not feasible for standard care. Bioelectrical impedance analysis (BIA) assesses body composition by incorporating the raw measurements resistance, reactance, and phase angle in equations. Our purpose was to compare BIA- and CT-derived muscle mass, to determine whether BIA identified the patients with low skeletal muscle area on CT-scan, and to determine the relation between raw BIA and raw CT measurements. Methods: This prospective observational study included adult intensive care patients with an abdominal CT-scan. CT-scans were analysed at L3 level for skeletal muscle area (cm2) and skeletal muscle density (Hounsfield Units). Muscle area was converted to muscle mass (kg) using the Shen equation (MMCT). BIA was performed within 72 h of the CT-scan. BIA-derived muscle mass was calculated by three equations: Talluri (MMTalluri), Janssen (MMJanssen), and Kyle (MMKyle). To compare BIA- and CT-derived muscle mass correlations, bias, and limits of agreement were calculated. To test whether BIA identifies low skeletal muscle area on CT-scan, ROC-curves were constructed. Furthermore, raw BIA and CT measurements, were correlated and raw CT-measurements were compared between groups with normal and low phase angle. Results: 110 patients were included. Mean age 59 ± 17 years, mean APACHE II score 17 (11–25); 68% male. MMTalluri and MMJanssen were significantly higher (36.0 ± 9.9 kg and 31.5 ± 7.8 kg, respectively) and MMKyle significantly lower (25.2 ± 5.6 kg) than MMCT (29.2 ± 6.7 kg). For all BIA-derived muscle mass equations, a proportional bias was apparent with increasing disagreement at higher muscle mass. MMTalluri correlated strongest with CT-derived muscle mass (r = 0.834, p < 0.001) and had good discriminative capacity to identify patients with low skeletal muscle area on CT-scan (AUC: 0.919 for males; 0.912 for females). Of the raw measurements, phase angle and skeletal muscle density correlated best (r = 0.701, p < 0.001). CT-derived skeletal muscle area and -density were significantly lower in patients with low compared to normal phase angle. Conclusions: Although correlated, absolute values of BIA- and CT-derived muscle mass disagree, especially in the high muscle mass range. However, BIA and CT identified the same critically ill population with low skeletal muscle area on CT-scan. Furthermore, low phase angle corresponded to low skeletal muscle area and -density. Trial registration: ClinicalTrials.gov (NCT02555670).
Objectives: The aim of this study was to assess the predictive value of PMA measurement for mortality. Background: Current surgical risk stratification have limited predictive value in the transcatheter aortic valve implantation (TAVI) population. In TAVI workup, a CT scan is routinely performed but body composition is not analyzed. Psoas muscle area (PMA) reflects a patient's global muscle mass and accordingly PMA might serve as a quantifiable frailty measure. Methods: Multi-slice computed tomography scans (between 2010 and 2016) of 583 consecutive TAVI patients were reviewed. Patients were divided into equal sex-specific tertiles (low, mid, and high) according to an indexed PMA. Hazard ratios (HR) and their confidence intervals (CI) were determined for cardiac and all-cause mortality after TAVI. Results: Low iPMA was associated with cardiac and all-cause mortality in females. One-year adjusted cardiac mortality HR in females for mid-iPMA and high-iPMA were 0.14 [95%CI, 0.05–0.45] and 0.40 [95%CI, 0.15–0.97], respectively. Similar effects were observed for 30-day and 2-years cardiac and all-cause mortality. In females, adding iPMA to surgical risk scores improved the predictive value for 1-year mortality. C-statistics changed from 0.63 [CI = 0.54–0.73] to 0.67 [CI: 0.58–0.75] for EuroSCORE II and from 0.67 [CI: 0.59–0.77] to 0.72 [CI: 0.63–0.80] for STS-PROM. Conclusions: Particularly in females, low iPMA is independently associated with an higher all-cause and cardiac mortality. Prospective studies should confirm whether PMA or other body composition parameters should be extracted automatically from CT-scans to include in clinical decision making and outcome prediction for TAVI.
