Postexercise Dietary Protein Ingestion Increases Whole-Body Leucine Balance in a Dose-Dependent Manner in Healthy Children

Abstract

Protein ingestion is important in enhancing whole-body protein balance in children. The effect of discrete bolus protein ingestion on acute postexercise recovery has yet to be determined. This study determined the effect of increasing doses of ingested protein on postexercise whole-body leucine balance in healthy, active children. Thirty-five children (26 boys, 9 girls; age range: 9-13 y; weight mean ± SD: 44.9 ± 10.6 kg) underwent a 5-d adaptation diet (0.95 g protein ⋅ kg ⋅ d) before performing 20 min of cycling 3 times with a concurrent, primed, constant infusion of [C]leucine. After exercise, participants consumed an isoenergetic beverage (140 kcal) containing variable amounts of bovine skim-milk protein and carbohydrates (sucrose) (0, 5, 10, and 15 g protein made up with 35, 30, 25, and 20 g carbohydrates, respectively). Blood and breath samples were taken over the 3 h of recovery to determine non-steady state whole-body leucine oxidation (Leu) and net leucine balance (Leu). Leu (secondary outcome) peaked 60 min after beverage ingestion and demonstrated a relative dose-response over the 3 h of recovery (15 g = 10 > 5 > 0 g; < 0.001). Leu (primary outcome) demonstrated a dose-response over the 3 h [15 g (24.2 ± 8.2 mg/kg) > 10 g (11.6 ± 4.3 mg/kg) > 5 g (5.7 ± 1.9 mg/kg) > 0 g (-3.0 ± 1.7 mg/kg); all < 0.01] with all conditions different from zero (all 0.001). Over the 3-h postexercise period, Leu was negative with carbohydrate ingestion alone; however, the co-ingestion of carbohydrates and 5 g high-quality dietary protein was sufficient to promote a positive postexercise whole-body protein balance in healthy, active children. Moreover, Leu increased in a dose-dependent manner within the protein range studied. Children should consider consuming a source of dietary protein after physical activity to enhance whole-body anabolism. This trial was registered at clinicaltrials.gov as NCT01598935.

Timing and pattern of postexercise protein ingestion affects whole-body protein balance in healthy children: a randomized trial

“…Specifically, we showed that post-exercise protein ingestion induced a dose-dependent increase in WBPB (determined by oral [ 15 N]glycine) over 9 h following a single bout of cycling exercise (Moore et al 2014), which we recently confirmed with a primed constant [ 13 C]leucine infusion over a 3-h recovery period (Volterman et al 2017). Despite the early dose-response, an intake of D r a f t 13 g (or ~0.32 g•kg -1 ) of protein immediately following exercise was required to maintain a positive WBPB over an entire 24-h period.…”

“…Thus, the pattern and not just the timing of protein intake outside of the early recovery period may be as (if not more) important to enhance net "growth" in exercising adults. We recently demonstrated that whole body leucine balance over 3h of recovery increases in a dose-dependent manner in healthy children (Volterman et al 2017).…”

“…We have recently demonstrated that post-exercise protein ingestion enhances whole body anabolism in healthy, active children (Volterman et al 2014, 2017, Moore et al 2014.…”

“…Therefore, as a secondary objective to our previous study (Volterman et al 2017), we examined whether the timing (i.e., immediate vs. delayed) and distribution (i.e., single or repeated doses) of protein intake in relation to an acute bout of exercise influenced WBPB and nitrogen balance (N BAL ) in healthy, active children consuming isonitrogenous diets.…”

ISPAD Clinical Practice Consensus Guidelines 2018: Exercise in children and adolescents with diabetes

“…The effects of various amounts of protein postexercise on net protein balance has also been evaluated in children without diabetes and showed that net protein balance was increased in a dose‐dependent manner within the protein range studied (0‐15 g). Thus, children with diabetes should consider consuming a source of dietary protein after physical activity to enhance whole‐body anabolism …”