Blood Flow Restriction (BFR) Training Effects

This randomized controlled trial study aims to evaluate the feasibility and preliminary efficacy of a combined inspiratory muscle training (IMT) and blood flow restriction (BFR) intervention in frail older adults. Outcomes of interest include feasibility, physical function, respiratory muscle strength, handgrip strength, five-times sit-to-stand performance, body composition, frailty level, fall efficacy, blood pressure, and adverse events.

Importance: Following anterior cruciate ligament reconstruction (ACLR), patients often experience quadriceps muscle weakness and atrophy, frequently leading to long-term complications. A promising rehabilitation program based on blood flow restriction training (BFRT) seems to be particularly valuable for patients who may be unable to train with heavy loads due recent surgery. Previous studies have demonstrated that BFRT promotes strength gains and muscle mass increases, with adaptations comparable to traditional high-intensity training, despite using low-load resistance exercises. Objective: to evaluate the effect of blood flow restriction training on quadriceps strength and knee biomechanics in a 4-month rehabilitation program of patients who have had an ACL reconstruction. Design: The study will be a two-arm superiority randomized controlled clinical trial. Setting: The trial will be conducted at a work-related injuries specialised hospital, MAZ Hospital, Zaragoza, Spain. Participants: Participants will be active workers who have suffered an acute ACL tear and they have undergone ACL reconstruction (n=60). Intervention: Patients will recieve a 14-16-week supervised accelerated early rehabilitation protocol; one group will complete it applying blood flow restriction training and the other will not. Main Outcome and Measure: The primary outcomes will be peak quadriceps strength and rate of torque development measured both isometrically and isokinetcally with a Isokinetic Dynamometer CON-TREX MG. Limitations: Potential limitations include patients and physiotherapists are not blinded. Conclusions: The focus of the research will examine the impact of blood flow restriction rehabilitation on patients who have undergone ACLR. Relevance: The study has potential to restore quadriceps strength to a greater extent than standard rehabilitation protocol. Moreover, patients will spend less time in the rehabilitation process to return to work compared to standard care.

Aging is a major risk factor for cardiovascular disease (CVD), contributing to progressive macrovascular and microvascular dysfunction. Macrovascular impairments, such as arterial stiffening and endothelial dysfunction, reduce nitric oxide (NO) bioavailability, leading to hypertension and impaired blood flow regulation. Microvascular dysfunction exacerbates cardiovascular decline by compromising capillary perfusion and tissue oxygenation, increasing susceptibility to ischemic events. Preserving vascular function is essential for maintaining cardiovascular health in aging populations. Low-intensity aerobic exercise (LIAE) improves cardiovascular health and mobility, particularly in populations unable to perform high-intensity exercise. However, LIAE alone often fails to induce significant vascular adaptations, such as improved arterial compliance or endothelial function, highlighting the need for optimized interventions. Blood Flow Restriction (BFR) enhances vascular adaptations during low-intensity exercise by inducing localized hypoxia, stimulating endothelial function and arterial remodeling. While BFR may transiently increase blood pressure and arterial stiffness, its vascular benefits resemble those of high-intensity exercise at lower workloads. However, research on BFR's acute vascular effects during aerobic exercise in older adults remains limited. Current studies have focused on perceptual and hemodynamic responses to LIAE+BFR but lack direct assessments of macrovascular (e.g., flow-mediated slowing) and microvascular function. Older adults may exhibit distinct vascular responses, yet data are scarce. This study examines acute vascular responses to LIAE+BFR and high-intensity interval exercise (HIIE) in young and older adults. Hypothesis: 1. BFR combined with LIAE will elicit greater acute microvascular and macrovascular responses in older adults than in younger adults. 2. These responses will be comparable to HIIE without BFR, suggesting BFR enhances LIAE's efficacy to high-intensity levels. 3. Any transient vascular dysfunction (e.g., increased arterial stiffness) will normalize within 30 minutes post-exercise, supporting safety in aging populations.