Acute ingestion of a ketone monoester, whey protein, or their co-ingestion in the overnight postabsorptive state elicit a similar stimulation of myofibrillar protein synthesis rates in young males: a double-blind randomized trial.

BACKGROUND: Ketone bodies may have anabolic effects in skeletal muscle via their capacity to stimulate protein synthesis. Whether orally ingested exogenous ketones can stimulate postprandial myofibrillar protein synthesis (MyoPS) rates with and without dietary protein co-ingestion is unknown. OBJECTIVES: This study aimed to evaluate the effects of ketone monoester intake and elevated blood ß-hydroxybutyrate (ß-OHB) concentration, with and without dietary protein co-ingestion, on postprandial MyoPS rates and mechanistic target of rapamycin complex 1 (mTORC1) pathway signaling. METHODS: In a randomized, double-blind, parallel group design, 36 recreationally active healthy young males (age: 24.2 ± 4.1 y; body fat: 20.9% ± 5.8%; body mass index: 23.4 ± 2 kg/m2) received a primed continuous infusion of L-[ring-2H5]-phenylalanine and ingested one of the following: 1) the ketone monoester (R)-3-hydroxybutyl (R)-3-hydroxybutyrate (KET), 2) 10 g whey protein (PRO), or 3) the combination of both (KET+PRO). Blood and muscle biopsy samples were collected during basal and postprandial (300 min) conditions to assess ß-OHB, glucose, insulin, and amino acid concentrations, MyoPS rates, and mTORC1 pathway signaling. RESULTS: Capillary blood ß-OHB concentration increased similarly during postprandial conditions in KET and KET+PRO, with both being greater than PRO from 30 to 180 min (treatment × time interaction: P < 0.001). Postprandial plasma leucine and essential amino acid (EAA) incremental area under the curve (iAUC) over 300 min was greater (treatment: both P < 0.001) in KET+PRO compared with PRO and KET. KET, PRO, and KET+PRO stimulated postprandial MyoPS rates (0-300 min) higher than basal conditions [absolute change: 0.020%/h; (95% CI: 0.013, 0.027%/h), 0.014%/h (95% CI: 0.009, 0.019%/h), 0.019%/h (95% CI: 0.014, 0.024%/h), respectively (time: P < 0.001)], with no difference between treatments (treatment: P = 0.383) or treatment × time interaction (interaction: P = 0.245). mTORC1 pathway signaling responses did not differ between treatments (all P > 0.05). CONCLUSIONS: Acute oral intake of a ketone monoester, 10 g whey protein, or their co-ingestion in the overnight postabsorptive state elicit a similar stimulation of postprandial MyoPS rates in healthy young males. This trial was registered at clinicaltrials.gov as NCT04565444 (https://clinicaltrials.gov/study/NCT04565444).

Evaluation of sex-based differences in resistance exercise training-induced changes in muscle mass, strength, and physical performance in healthy older (≥60 y) adults: A systematic review and meta-analysis.

The objective of this systematic review and meta-analysis was to determine if there are sex-based differences in adaptations to resistance exercise training in healthy older adults. Following the screening process, data from 36 studies comparing older males and females (602 males; 703 females; ≥60 years of age) for changes in skeletal muscle size, muscle strength, and/or physical performance following the same resistance exercise training intervention were extracted. Mean study quality was 16/29 (modified Downs and Black checklist), considered moderate quality. Changes in absolute upper-body (Effect Size [ES] = 0.81 [95% CI 0.54, 1.09], P < 0.001), and lower-body (ES = 0.40 [95% CI 0.24, 0.56], P < 0.001) strength were greater in older males than females. Alternatively, changes in relative upper-body (ES = -0.46 [95% CI -0.77, -0.14], P < 0.01), and lower-body (ES = -0.24 [95% CI -0.42, -0.06], P < 0.01) strength were greater in older females than males. Changes in absolute, but not relative, whole-body fat-free mass (ES = 0.18 [95% CI 0.04, 0.33], P < 0.05) were greater in older males than females. There were no sex-based differences for absolute or relative changes in limb muscle size, muscle fiber size, or physical performance.

Outcomes of peer mentorship for people living with spinal cord injury: perspectives from members of Canadian community-based SCI organizations.

STUDY DESIGN: A generic qualitative design. OBJECTIVES: To obtain a deeper understanding of the outcomes of spinal cord injury (SCI) peer mentorship programs delivered by community-based organizations. SETTING: Peer mentorship programs of community-based SCI organizations METHODS: We interviewed 36 individuals who shared their experiences of SCI peer mentorship from the perspective of a peer mentee, peer mentor, or family member of a peer mentee/mentor, or staff of SCI community-based organizations. Interview data were analyzed using an inductive thematic analysis approach. RESULTS: Four overarching themes with sub-themes were identified. (1) Positive outcomes for mentees such as understanding, emotional outlet/psychological support, inspiration/hope, and belonging. (2) Positive outcomes for mentors such as gaining gratitude, confidence, pride, and personal growth. (3) Reciprocity in positive/negative outcomes for mentors and mentees, such as shared learning and a lack of connection. (4) Negative outcomes for mentors such as impact of negativity, emotional toll, and time/energy demands. CONCLUSIONS: Peer mentorship programs delivered by community-based SCI organizations are important, impactful resources for individuals with SCI who engage in these programs. These results provide insights into the variety of positive and negative outcomes linked with these programs.

Understanding peer mentorship programs delivered by Canadian SCI community-based organizations: perspectives on mentors and organizational considerations.

STUDY DESIGN: The study used a generic qualitative design. OBJECTIVES: This article set out to garner knowledge of peer mentorship programs delivered by SCI community-based organizations by interviewing people who are directly and in-directly involved with these programs. SETTING: Four provincial community-based SCI organizations across Canada. An integrated knowledge translation approach was applied in which researchers and SCI organization members co-constructed, co-conducted, and co-interpreted the study. METHODS: Thirty-six individuals (N = 36, including peer mentees, mentors, family members of mentees, and organizational staff) from four provincial SCI community-based organizations were interviewed. The participants' perspectives were combined and analyzed using a thematic analysis. RESULTS: Two overarching themes with respective subthemes were identified. Mentorship Mechanics describes the characteristics of mentors and mentees and components of the mentor-mentee relationship (e.g., establish a common ground). Under the theme Peer Mentorship Program Structures, participants described the organizational considerations for peer mentorship programs (e.g., format), and organizational responsibilities (e.g., funding; creating a peer mentorship team). CONCLUSION: This study provides an in-depth look at the characteristics of peer mentorship programs that are delivered by community-based organizations in Canada and highlights the complexity of delivering such programs.