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

Abstract

Glucose ingestion and absorption into the blood stream 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±3yr, 7 female) we tracked post-glucose (oral 100g) glycemic, cardiometabolic and vascular function measures over 120min following four interventions: 1) BFR, 2) EMS, 3) BFR+EMS or 4) Control. BFR was applied at 2min intervals for 30min (70% occlusion), EMS was continuous for 30min (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 60min post-glucose ingestion across interventions and recovered by 120min (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±519mL•min-1, +433±510mL•min-1; P<0.001); however, only remained elevated following BFR intervention 90min post-glucose (+94±94mL•min-1; P=0.02). Superimposition of EMS onto cyclic BFR did not preferentially improve post-glucose metabolic or vascular function amongst young, active participants. Cyclic BFR increased blood flow delivery 60min beyond intervention, and BFR+EMS selectively increased carbohydrate usage and reduced muscle oxygenation warranting future clinical assessments.

Effects of Whole-Body Vibration Combined with Blood Flow Restriction and Systemic Hypoxia on Body Composition and Physical Performance in Overweight University Students

“…Overall, changes in muscular strength in all three groups tended to improve. This is consistent with previous studies that blood flow restriction training was found to improve muscular strength (Cai et al, 2021;Cohen et al, 2022) or even whole-body vibration training alone can also increase muscular strength (Berner et al, 2020;Hegazy et al, 2021;Lai et al, 2021). This was especially true in the WBV+HYP group, where changes were similar to those in the BFR group.…”

Effects of neuromuscular electrical stimulation on glycemic control: a systematic review and meta-analysis

“…To our knowledge seven studies have reported the acute effects of NMES on substrate utilization measured by Respiratory Quotient (RQ) or Respiratory Exchange Ratio (RER), oxygen consumption (VO2), and lactate production. All these studies indicate increased glucose utilization during NMES application as measured by increased RQ ( 50 , 51 , 77 , 78 , 83 , 84 ), increased lactate level ( 50 , 51 , 61 , 77 , 78 ) or elevated oxygen utilization ( 50 , 51 , 77 , 78 , 83 ) (see Table, Supplementary Table 2 ). Additionally, three studies reported on energy expenditure during NMES.…”

“…Two other studies reported an increase in whole body carbohydrate utilization using a Douglas Bag method ( 84 ) while Cohen et al. showed an additive effect of NMES with blood flow restriction on carbohydrate utilization ( 83 ). An increased whole body oxygen uptake measured by RER has been noted at the onset of low frequency electrical stimulation, followed by an immediate return to resting levels at the termination of stimulation ( 77 , 78 ).…”

“…Using these same endpoints, NMES is being used for body contouring in aesthetic medicine to selectively increase muscle mass and tone in muscle groups of the body ( 66 , 84 ). NMES is also being used to increase blood flow in the extremities to avoid blood clots and promote wound healing ( 83 ). Understanding that NMES can improve glycemic control, it has a potential to be incorporated into the multidimensional (diet, exercise, behavior modification, and pharmaceuticals) treatment of obesity, metabolic syndrome, and type 2 diabetes as a complement or when traditional exercise modalities are not feasible.…”

“…In addition to an increased glucose disposal rate, Hamada et al demonstrated maintaining this elevated glucose uptake for at least 90 minutes following the cessation of NMES application, which also showed a greater requirement for glucose during the poststimulation period (77). Other studies, however, did not observe any significant acute effect of NMES on postprandial glucose level among healthy active participants (69,83,84). Combining whole body NMES with voluntary exercise has also shown an additive effect in elevating RQ and increasing blood lactate concentration (92).…”