Clinical Trial Details
— Status: Completed
Administrative data
| NCT number |
NCT04887883 |
| Other study ID # |
TUT study |
| Secondary ID |
RGPIN-2015-04521 |
| Status |
Completed |
| Phase |
|
| First received |
|
| Last updated |
|
| Start date |
January 1, 2019 |
| Est. completion date |
September 1, 2019 |
Study information
| Verified date |
May 2021 |
| Source |
University of Toronto |
| Contact |
n/a |
| Is FDA regulated |
No |
| Health authority |
|
| Study type |
Observational
|
Clinical Trial Summary
Acute exercise increases the incorporation of dietary amino acids into de novo myofibrillar
proteins after a single meal in controlled laboratory studies in males. It is unclear if this
extends to free-living settings or is influenced by training or sex. Over 24 h in a
free-living setting, the investigators determined the effect of training status and sex on
dietary phenylalanine incorporation into contractile myofibrillar and noncontractile
sarcoplasmic proteins after exercise.
Description:
Exogenous (e.g. diet-derived) amino acids increase muscle protein synthesis and provide the
building blocks for growth. While traditional infusion studies can measure the synthesis of
total mixed muscle or fraction-specific protein synthetic rates, the metabolic fate of
dietary amino acids can only be assessed by measuring the incorporation of a labelled amino
acid (i.e. L-[1-13C]phenylalanine) into muscle protein through the oral ingestion of a
intrinsically labelled food source (e.g. milk protein) . This technique has revealed in
controlled laboratory settings that dietary amino acids, and not endogenous amino acids
recycled from intracellular protein breakdown, may be preferentially utilized as precursors
for muscle and whole body protein synthesis Therefore, it is important to characterize the
incorporation of diet-derived amino acids over a 24-h post-exercise recovery period to
determine how RE influences their utilization as precursors for the synthesis of new muscle
proteins. The investigators are unaware of any studies that have examined the utilization of
dietary amino acids for de novo muscle protein synthesis in females, highlighting an urgent
need to rectify the sex-disparity in exercise-related research.
Protein requirements during resistance training have been suggested to be highest at training
onset with evidence suggesting moderate daily intakes (~1.2-1.4 g·kg·d-1) can support chronic
adaptations, although recent suggestions are that slightly higher intakes (~1.6 g·kg·d-1) may
optimize lean mass growth. Resistance training is associated with a reduction in whole-body
protein turnover but an increased net protein balance suggesting a greater efficiency of
whole-body amino acid utilization with training in males , although whether this also extends
to females is unknown. Acute RE and chronic training has been reported to increase
intracellular amino acid recycling in the fasted state, which would be consistent with an
increased amino acid efficiency. To date, however, no study has investigated whether the
post-exercise incorporation of dietary amino acids into myofibrillar and sarcoplasmic
proteins in a free-living setting is modified by training and/or sex.
The primary aim of the present study was to determine the dietary fate of amino acids into
contractile myofibrillar and noncontractile sarcoplasmic muscle proteins after acute RE in
the untrained and trained state over 24 h in a free-living setting. The investigators
hypothesized that, irrespective of sex, acute RE would increase dietary amino acid
incorporation in myofibrillar proteins in the untrained state with training leading to an
attenuated increase suggestive of a reduced reliance on dietary amino acids in the trained
state.
