Abstract
PurposeTo investigate the mechanisms underpinning modifications in glucose homeostasis and insulin sensitivity 24 h after a bout of resistance exercise (RE) with or without protein ingestion.MethodsTwenty-four healthy males were assigned to a control (CON; n = 8), exercise (EX; n = 8) or exercise plus protein condition (EX+PRO; n = 8). Muscle biopsy and blood samples were obtained at rest for all groups and immediately post-RE (75% 1RM, 8×10 repetitions of leg-press and extension exercise) for EX and EX+PRO only. At 24 h post-RE (or post-resting biopsy for CON), a further muscle biopsy was obtained. Participants then consumed an oral glucose load (OGTT) containing 2 g of [U-13C] glucose during an infusion of 6, 6-[2H2] glucose. Blood samples were obtained every 10 min for 2 h to determine glucose kinetics. EX+PRO ingested an additional 25 g of intact whey protein with the OGTT. A final biopsy sample was obtained at the end of the OGTT.ResultsFasted plasma glucose and insulin were similar for all groups and were not different immediately post- and 24 h post-RE. Following RE, muscle glycogen was 26±8 and 19±6% lower in EX and EX+PRO, respectively. During OGTT, plasma glucose AUC was lower for EX and EX+PRO (75.1±2.7 and 75.3±2.8 mmol·L−1∶120 min, respectively) compared with CON (90.6±4.1 mmol·L−1∶120 min). Plasma insulin response was 13±2 and 21±4% lower for EX and CON, respectively, compared with EX+PRO. Glucose disappearance from the circulation was ∼12% greater in EX and EX+PRO compared with CON. Basal 24 h post-RE and insulin-stimulated PAS-AS160/TBC1D4 phosphorylation was greater for EX and EX+PRO.ConclusionsPrior RE improves glycemic control and insulin sensitivity through an increase in the rate at which glucose is disposed from the circulation. However, co-ingesting protein during a high-glucose load does not augment this response at 24 h post-exercise in healthy, insulin-sensitive individuals.
Highlights
Metabolic complications, such as insulin resistance and Type II diabetes, represent a major individual and public health burden [1] and are associated with the presence of obesity and physical inactivity [2,3,4]
Based on the measured 1 Repetition Maximum (1RM), the resistance lifted on the leg-press machine during Day 1 was 150617 and 156617 kg and for EX and exercise plus protein condition (EX+PRO), respectively (P.0.05)
Six participants were unable to complete the legextension exercise at the desired resistance, which was lowered by 2.5–5 kg to enable participants to complete ten repetitions
Summary
Metabolic complications, such as insulin resistance and Type II diabetes, represent a major individual and public health burden [1] and are associated with the presence of obesity and physical inactivity [2,3,4]. Skeletal muscle contraction can effectively enhance glucose uptake independent of insulin These properties are preserved in individuals with Type II diabetes [11,12]. Evidence has emerged to suggest that a single bout of resistance exercise (RE) improves whole-body insulin sensitivity [17,18,19] and glycemic control [20], with the beneficial effects of RE on glycemic control and insulin sensitivity noted primarily between 12–24 h post-RE. Not all studies demonstrate a beneficial effect of RE on glucose metabolism [21,22]
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