title: Time course of regional vascular adaptations to low load resistance training with blood flow restriction.
abstract: Distortion to hemodynamic and ischemic stimuli during blood flow restriction (BFR) exercise may influence regional vascular adaptation. We examined changes at the conduit, resistance, and capillary level in response to low load resistance exercise with BFR. Eleven males (22 ± 3 yr, 178 ± 4 cm, 78 ± 9 kg) completed 6 wk (3 days/wk) unilateral plantar flexion training with BFR at 30% 1 repetition maximum (1-RM). The contralateral leg acted as a nonexercised control (CON). Popliteal artery function [flow-mediated dilation, FMD%] and structure [maximal diameter] and resistance vessel structure [peak reactive hyperemia] were assessed using Doppler ultrasound before and at 2-wk intervals. Calf filtration capacity was assessed using venous occlusion plethysmography before and after training. BFR training elicited an early increase in peak reactive hyperemia (1,400 ± 278 vs. 1,716 ± 362 ml/min at 0 vs. 2 wk; t-test: P = 0.047), a transient improvement in popliteal FMD% (5.0 ± 2.1, 7.6 ± 2.9, 6.6 ± 2.1, 5.7 ± 1.6% at 0, 2, 4 and 6 wk, respectively; ANOVA: P = 0.002), and an increase in maximum diameter (6.06 ± 0.44 vs. 6.26 ± 0.39 mm at 0 vs. 6 wk; Bonferroni t-test: P = 0.048). Capillary filtration increased after 6 wk BFR training (P = 0.043). No changes in the CON leg were observed. Adaptation occurred at all levels of the vascular tree in response to low load resistance exercise with BFR. Enhanced peak reactive hyperemia and transient improvement in popliteal artery function occurred before changes in artery structural capacity.
authors.affiliation: School of Sport, Exercise and Health Sciences, Loughborough University, Loughborough, United Kingdom.
authors.forename: Julie E A
authors.initials: JE
authors.lastname: Hunt
authors.forename: Dermot
authors.initials: D
authors.lastname: Galea
authors.forename: Graham
authors.initials: G
authors.lastname: Tufft
authors.forename: Danny
authors.initials: D
authors.lastname: Bunce
authors.forename: Richard A
authors.initials: RA
authors.lastname: Ferguson
mesh_terms: D000222:Adaptation, Physiological / Q000502:physiology*; D000328:Adult; D000704:Analysis of Variance; D001158:Arteries / Q000000981:diagnostic imaging / Q000502:physiology*; D002196:Capillaries / Q000502:physiology; D006439:Hemodynamics / Q000502:physiology; D006801:Humans; D007511:Ischemia / Q000503:physiopathology; D007866:Leg / Q000098:blood supply; D008297:Male; D008954:Models, Biological; D010991:Plethysmography; D011150:Popliteal Artery / Q000000981:diagnostic imaging / Q000502:physiology; D012039:Regional Blood Flow / Q000502:physiology; D055070:Resistance Training / Q000379:methods*; D018608:Ultrasonography, Doppler; D014655:Vascular Resistance; D014664:Vasodilation / Q000502:physiology; D055815:Young Adult
keywords: capillarity; ischemic exercise; plantar flexion; popliteal artery; structure and function