Acute Blood Flow Responses to Varying Blood Flow Restriction Pressures in the Lower Limbs

International Journal of Exercise Science 16(2): 118-128, 2023. The purpose of this study was to investigate lower limb blood flow responses under varying blood flow restriction (BFR) pressures based on individualized limb occlusion pressures (LOP) using a commonly used occlusion device. Twenty-nine participants (65.5% female, 23.8 ± 4.7 years) volunteered for this study. An 11.5cm tourniquet was placed around participants’ right proximal thigh, followed by an automated LOP measurement (207.1 ± 29.4mmHg). Doppler ultrasound was used to assess posterior tibial artery blood flow at rest, followed by 10% increments of LOP (10-90% LOP) in a randomized order. All data were collected during a single 90-minute laboratory visit. Friedman’s and one-way repeated-measures ANOVAs were used to examine potential differences in vessel diameter, volumetric blood flow (VolFlow), and reduction in VolFlow relative to rest (%Rel) between relative pressures. No differences in vessel diameter were observed between rest and all relative pressures (all p \u3c .05). Significant reductions from rest in VolFlow and %Rel were first observed at 50% LOP and 40% LOP, respectively. VolFlow at 80% LOP, a commonly used occlusion pressure in the legs, was not significantly different from 60% (p = .88), 70% (p = .20), or 90% (p = 1.00) LOP. Findings indicate a minimal threshold pressure of 50%LOP may be required to elicit a significant decrease in arterial blood flow at rest when utilizing the 11.5cm Delfi PTSII tourniquet system

Acute Responses to High-Intensity Back Squats with Bilateral Blood Flow Restriction

This study examined the acute effects of high-intensity resistance exercise with blood flow restriction (BFR) on performance and fatigue, metabolic stress, and markers of inflammation (interleukin-6 (IL-6)), muscle damage (myoglobin), angiogenesis (vascular endothelial growth factor (VEGF)). Thirteen resistance-trained participants (four female, 24.8 ± 4.7 years) performed four sets of barbell back-squats (75% 1RM) to failure under two conditions: blood flow restriction (BFR, bilateral 80% occlusion pressure) and control (CTRL). Completed repetitions and pre–post-exercise changes in maximal voluntary isometric contractions, countermovement jump, barbell mean propulsive velocity, and surface electromyography were recorded. Pre–post blood lactate (BLa) and venous blood samples for analysis of IL-6, myoglobin, and VEGF were collected. Ratings of perceived exertion (RPE) and pain were recorded for each set. Fewer repetitions were performed during BFR (25.5 ± 9.6 reps) compared to CTRL (43.4 ± 14.2 reps, p < 0.001), with greater repetitions performed during sets 1, 2, and 4 (p < 0.05) in CTRL. Although RPE between conditions was similar across all sets (p > 0.05), pain was greater in BFR across all sets (p < 0.05). Post-exercise fatigue was comparable between conditions. BLa was significantly greater in CTRL compared to BFR at two minutes (p = 0.001) but not four minutes post-exercise (p = 0.063). IL-6 was significantly elevated following BFR (p = 0.011). Comparable increases in myoglobin (p > 0.05) and no changes in VEGF were observed (p > 0.05). BFR increases the rate of muscular fatigue during high-intensity resistance exercise and acutely enhances IL-6 response, with significantly less total work performed, but increases pain perception, limiting implementation

Associations between multimodal fitness assessments and rowing ergometer performance in collegiate female athletes

The purpose was to examine the association of critical power from a three-minute all-out row (C

Proteomic analysis of cardiorespiratory fitness for prediction of mortality and multisystem disease risks.

Acknowledgements: A.S.P. is supported by the AHA (20SFRN35120123). J.M.R. is supported by the National Institutes of Health (NIH) (K23HL150327). R.V.S. is supported by grants from the American Heart Association (AHA) and NIH. M.N. is supported by NIH (R01HL156975, R01HL131029) and by a Career Investment Award from the Department of Medicine, Boston University School of Medicine. R.E.G. and M.A.S. were funded by R01NR019628. T.T., K.A.W., and L.F. are supported by the National Institute on Aging’s Intramural Research Program. P.R. is supported by the John S. LaDue Memorial Fellowship at Harvard Medical School. Q.S.W. is supported by the NIH (R01HL140074). M.Y.M. was supported by the NIH (K23HL171855). B.C. is supported by an Early Career Investigator Grant from the American Lung Association. The BLSA study was funded by the National Institute on Aging’s Intramural Research Program. Proteomics in CARDIA were funded by a grant to R.K. (R01HL122477). CARDIA is conducted and supported by the National Heart, Lung, and Blood Institute (NHLBI) in collaboration with the University of Alabama at Birmingham (75N92023D00002 and 75N92023D00005), Northwestern University (75N92023D00004), University of Minnesota (75N92023D00006) and Kaiser Foundation Research Institute (75N92023D00003). This manuscript has been reviewed by CARDIA for scientific content. Exercise testing in CARDIA was funded by a grant to S.S. and B. Sternfeld (R01HL078972). The Fenland Study is funded by the UK Medical Research Council, with proteomic assessment funded by Somalogic; Investigators T.G., N.J.W. and S.B. received support from the UK Medical Research Council (MC_UU_00006/1, MC_UU_00006/4) as well as the National Institute for Health and Care Research Cambridge Biomedical Research Centre (IS-BRC-1215-20014). The HERITAGE study was supported by several grants from the NHLBI (R01HL45670, R01HL47317, R01HL47321, R01HL47323 and R01HL47327).Despite the wide effects of cardiorespiratory fitness (CRF) on metabolic, cardiovascular, pulmonary and neurological health, challenges in the feasibility and reproducibility of CRF measurements have impeded its use for clinical decision-making. Here we link proteomic profiles to CRF in 14,145 individuals across four international cohorts with diverse CRF ascertainment methods to establish, validate and characterize a proteomic CRF score. In a cohort of around 22,000 individuals in the UK Biobank, a proteomic CRF score was associated with a reduced risk of all-cause mortality (unadjusted hazard ratio 0.50 (95% confidence interval 0.48-0.52) per 1 s.d. increase). The proteomic CRF score was also associated with multisystem disease risk and provided risk reclassification and discrimination beyond clinical risk factors, as well as modulating high polygenic risk of certain diseases. Finally, we observed dynamicity of the proteomic CRF score in individuals who undertook a 20-week exercise training program and an association of the score with the degree of the effect of training on CRF, suggesting potential use of the score for personalization of exercise recommendations. These results indicate that population-based proteomics provides biologically relevant molecular readouts of CRF that are additive to genetic risk, potentially modifiable and clinically translatable