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The effects of bolus versus pulse feeding strategies on muscle anabolism in older men
Author(s) -
Mitchell William Kyle,
Williams John,
Rankin Debbie,
Lund Jonathan,
Phillips Bethan,
Smith Kenneth,
Atherton Philip J
Publication year - 2013
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.27.1_supplement.1208.3
Subject(s) - anabolism , bolus (digestion) , medicine , endocrinology , ingestion , sarcopenia , analysis of variance , chemistry
A topical advancement in understanding the control of muscle protein synthesis (MPS) was the discovery of a “Muscle‐Full” phenomenon, whereby feeding stimulates only transient increases in MPS, which return to postabsorptive values despite sustained availability of plasma and muscle essential amino acids (EAA) including leucine. Herein, we have explored this phenomenon in relation to aging by measuring MPS ( 13 C 6 ‐phenylalanine bound muscle) over a 6 h period (2 h fasted ‐4 h fed) using two distinct feeding regimens: 16 older men received either a single 15g mixed EAA feed (N=8, 70±2 y; ‘BOLUS’) or the same dose in 4 × 3.75g fractions at 45 min intervals (N=8, 70±3 y; ‘PULSE’). While MPS was unchanged in either group 0–90 min after EAA ingestion, it was elevated 91–180 min, irrespective of feeding strategy (BOLUS: 0.049 to 0.082 vs. PULSE: 0.046 to 0.071%.h −1 , P<0.05 2‐way RM ANOVA). In contrast, while MPS returned to baseline rates in BOLUS between 181–240 min (to 0.052%.h −1 ) this was not the case in PULSE (0.070%.h −1 , P<0.05). Despite these temporal differences equal total MPS responses to feeding regimens were revealed by area under the curve analysis (0.27% vs. 0.24% in 4 h, P>;0.05). While equal total MPS between regimens suggests a dose, not time‐dependent mechanism regulates the muscle‐full state in older men, greater sustainment of the anabolic response over longer durations with PULSE feeding regimens may transpire.