Exercise, protein metabolism, and muscle growth.
Level 5 - mechanism / opinion, no new human data
Narrative review of metabolic mechanisms with no systematic search methodology reported
PubMed 11255140 · doi:10.1123/ijsnem.11.1.109
What was done
This narrative review summarizes the interactions between resistance exercise, hormonal responses (insulin and testosterone), and dietary amino acid availability on muscle protein synthesis and breakdown. No study selection criteria, search strategy, or sample sizes are reported in the abstract.
What was found
The abstract reports qualitative mechanistic conclusions without numerical data. Resistance exercise alone improves muscle protein balance, but net balance remains negative (catabolic) without feeding. The metabolic response to a single resistance training bout persists for 24 to 48 hours. Ingesting amino acids—even in small amounts, particularly when paired with carbohydrates—interacts with post-exercise metabolic pathways to maximize protein synthesis and induce net anabolism. Post-exercise insulin acts permissively on muscle protein synthesis and primarily functions to suppress muscle protein breakdown.
Why it matters
The review outlines the physiological necessity of pairing post-exercise feeding with resistance training to achieve positive net protein balance during the 24- to 48-hour recovery window.
Limits
As a narrative review, the abstract presents no original trial data, meta-analytic pooling, or quantitative effect sizes. Furthermore, the abstract explicitly notes that it remains unknown whether transient, acute elevations in muscle protein anabolism directly translate into chronic muscle hypertrophy over prolonged training programs.
Cited by
- supports Post-resistance training elevation in muscle protein synthesis lasts for at least 24 hours.