Augmented Anabolic Responses after 8-wk Cycling with Blood Flow Restriction

TLDR

Low‑intensity endurance training with blood‑flow restriction can improve muscle strength, cross‑sectional area, and cardiorespiratory capacity, but it is unclear whether these adaptations match those from resistance or conventional endurance training. The study aimed to compare the 8‑week functional, morphological, and molecular responses of ET‑BFR with conventional resistance training and endurance training. Thirty healthy young men were randomized to 8 weeks of ET‑BFR (4 days wk, 30 min cycling at 40 % VO₂max), RT (4 days wk, 4 × 10 leg press at 70 % 1RM), or ET (4 days wk, 30 min cycling at 70 % VO₂max), with quadriceps CSA, leg‑press 1RM, VO₂max, and muscle biopsies measured pre‑ and post‑intervention. Eight weeks of ET‑BFR increased muscle strength and hypertrophy comparable to RT, while also raising VO₂max, cytochrome‑c oxidase subunit 4 isoform 1, and VEGF mRNA levels despite a lower workload, highlighting molecular mechanisms that support its potential to enhance muscle and cardiorespiratory.

Abstract

Low-intensity endurance training (ET) performed with blood flow restriction (BFR) can improve muscle strength, cross-sectional area (CSA) and cardiorespiratory capacity. Whether muscle strength and CSA as well as cardiorespiratory capacity (i.e., V˙O2max) and underlying molecular processes regulating such respective muscle adaptations are comparable to resistance and ET is unknown.To determine the respective chronic (i.e., 8 wk) functional, morphological, and molecular responses of ET-BFR training compared with conventional, unrestricted resistance training (RT) and ET.Thirty healthy young men were randomly assigned to one of three experimental groups: ET-BFR (n = 10, 4 d·wk, 30-min cycling at 40% of V˙O2max), RT (n = 10, 4 d·wk, 4 sets of 10 repetitions leg press at 70% of one repetition maximum with 60 s rest) or ET (n = 10, 4 d·wk, 30-min cycling at 70% of V˙O2max) for 8 wk. Measures of quadriceps CSA, leg press one repetition maximum, and V˙O2max as well as muscle biopsies were obtained before and after intervention.Both RT and ET-BFR increased muscle strength and hypertrophy responses. ET-BFR also increased V˙O2max, total cytochrome c oxidase subunit 4 isoform 1 abundance and vascular endothelial growth factor mRNA abundance despite the lower work load compared to ET.Eight weeks of ET-BFR can increase muscle strength and induce similar muscle hypertrophy responses to RT while V˙O2max responses also increased postintervention even with a significantly lower work load compared with ET. Our findings provide new insight to some of the molecular mechanisms mediating adaptation responses with ET-BFR and the potential for this training protocol to improve muscle and cardiorespiratory capacity.