Blood flow restriction and stimulated muscle contractions do not improve metabolic or vascular outcomes following glucose ingestion in young, active individuals

Glucose ingestion and absorption into the bloodstream can challenge glycemic regulation and vascular endothelial function. Muscular contractions in exercise promote a return to homeostasis by increasing glucose uptake and blood flow. Similarly, muscle hypoxia supports glycemic regulation by increasing glucose oxidation. Blood flow restriction (BFR) induces muscle hypoxia during occlusion and reactive hyperemia upon release. Thus, in the absence of exercise, electric muscle stimulation (EMS) and BFR may offer circulatory and glucoregulatory improvements. In 13 healthy, active participants (27 ± 3 yr, 7 females), we tracked post-glucose (oral 100 g) glycemic, cardiometabolic, and vascular function measures over 120 min following four interventions: 1) BFR, 2) EMS, 3) BFR + EMS, or 4) control. BFR was applied at 2-min intervals for 30 min (70% occlusion), and EMS was continuous for 30 min (maximum-tolerable intensity). Glycemic and insulinemic responses did not differ between interventions (partial η2 = 0.11–0.15, P = 0.2), however, only BFR + EMS demonstrated cyclic effects on oxygen consumption, carbohydrate oxidation, muscle oxygenation, heart rate, and blood pressure (all P < 0.01). Endothelial function was reduced 60 min post-glucose ingestion across interventions and recovered by 120 min (5.9 ± 2.6% vs 8.4 ± 2.7%; P < 0.001). Estimated microvascular function was not meaningfully different. Leg blood flow increased during EMS and BFR + EMS (+656 ± 519 mL·min−1, +433 ± 510 mL·min−1; P < 0.001); however, only remained elevated following BFR intervention 90 min post-glucose (+94 ± 94 mL·min−1; P = 0.02). Superimposition of EMS onto cyclic BFR did not preferentially improve post-glucose metabolic or vascular function among young, active participants. Cyclic BFR increased blood flow delivery 60 min beyond intervention, and BFR + EMS selectively increased carbohydrate usage and reduced muscle oxygenation warranting future clinical assessments.

NEW & NOTEWORTHY
Glucose ingestion challenges glycemic and vascular function. Exercise effectively counteracts these impairments, but is not always feasible. Blood flow restriction (BFR) and electric muscle stimulation (EMS) passively generate muscle hypoxia and contractions mimicking aspects of exercise. We tested BFR, EMS, and BFR + EMS in young, active participants post-glucose. No significant primary glycemic or vascular outcomes are observed. Cyclic BFR increased leg blood flow while BFR + EMS activated greater carbohydrate oxidation and lowered muscle oxygenation warranting future consideration.