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Associations Between Estimates of Arterial Stiffness and Cognitive Functioning in Adults With HIV. J Acquir Immune Defic Syndr 2024; 95:456-462. [PMID: 38133605 PMCID: PMC10951550 DOI: 10.1097/qai.0000000000003374] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2023] [Accepted: 12/07/2023] [Indexed: 12/23/2023]
Abstract
BACKGROUND Vascular aging, a precursor of arterial stiffness, is associated with neurocognitive impairment (NCI) and cardiovascular disease. Although HIV is associated with rapid vascular aging, it is unknown whether arterial stiffness mediates changes in cognitive function. We explored whether estimated markers of vascular aging were associated with NCI indices in HIV-positive individuals. METHODS This study was a secondary analysis of an observational study. Neurocognitive functioning was assessed using a battery of 7 domains (verbal fluency, executive functioning, speed of information processing, attention/working memory, memory [learning and delayed recall], and motor skills). Vascular aging was assessed using estimated markers of arterial stiffness (ie, estimated pulse wave velocity, pulse pressure, and vascular overload index). A multivariable regression adjusted for demographics, cardiovascular disease risk factors, and HIV clinical variables was used to examine the association between vascular aging and NCI outcomes. RESULTS Among 165 people with HIV, the mean age was 51.5 ± 6.9 years (62% men and 83% African American/Black or Other). In fully adjusted models, an increase in estimated pulse wave velocity and pulse pressure was associated with lower T scores in learning (-2.95 [-5.13, -0.77]) and working memory (-2.37 [-4.36, -0.37]), respectively. An increase in vascular overload index was associated with lower T scores in working memory (-2.33 [-4.37, -0.29]) and learning (-1.85 [-3.49, -0.21]). CONCLUSIONS Estimated markers of arterial stiffness were weakly associated with neurocognitive functioning, suggesting that vascular aging may have a role in cognitive decline among people with HIV.
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Post-occlusive reactive hyperemia in habituated caffeine users: Effects of abstaining versus consuming typical doses. Clin Hemorheol Microcirc 2024:CH232036. [PMID: 38250766 DOI: 10.3233/ch-232036] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2024]
Abstract
BACKGROUND Post-occlusive reactive hyperemia (PORH) typically requires caffeine abstinence. For habitual users, it is unknown if abstinence affects PORH. OBJECTIVE Compare PORH after habitual users consume or abstain from caffeine. METHODS On separate visits (within-subject), PORH was measured in 30 participants without abstinence from typical caffeine doses (CAFF) and with abstinence (ABS). Measurements included baseline and peak hyperemic velocity, tissue saturation index slopes during ischemia (Slope 1) and following cuff deflation (Slope 2), resting arterial occlusion pressure (AOP), heart rate (HR), systolic (SBP), and diastolic (DBP) blood pressure. All variables were compared using Bayesian paired t-tests. BF10 = likelihood of alternative vs null. Results are mean±SD. RESULTS Comparing baseline velocity (cm/s) between CAFF (9.3±4.8) and ABS (7.5±4.9) yielded anecdotal evidence (BF10 = 1.0). Peak hyperemic velocity (cm/s) was similar (CAFF = 77.3±16.7; ABS = 77.6±19.0, BF10 = 0.20). For slopes (TSI% /s), CAFF Slope 1 = -0.11±0.04 and Slope 2 = 1.9±0.46 were similar (both BF10≤0.20) to ABS Slope 1 = -0.12±0.03 and Slope 2 = 1.8±0.42. SBP and DBP (mmHg) were both similar (CAFF SBP = 116.0±9.8, DBP = 69.6±5.8; ABS SBP = 115.5±10.7, DBP = 69.5±5.4; both BF10≤0.22). Comparing AOP (mmHg) (CAFF = 146.6±15.0; ABS = 143.0±16.4) yielded anecdotal evidence (BF10 = 0.46). HR (bpm) was similar (CAFF = 66.5±12.3; ABS = 66.9±13.0; BF10 = 0.20). CONCLUSIONS In habitual users, consuming or abstaining from typical caffeine doses does not appear to affect post-occlusive reactive hyperemia.
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Skeletal Muscle Adaptations to High-Load Resistance Training With Pre-Exercise Blood Flow Restriction. J Strength Cond Res 2023; 37:2381-2388. [PMID: 37535935 DOI: 10.1519/jsc.0000000000004553] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/05/2023]
Abstract
ABSTRACT Hammert, WB, Moreno, EN, Martin, CC, Jessee, MB, and Buckner, SL. Skeletal muscle adaptations to high-load resistance training with pre-exercise blood flow restriction. J Strength Cond Res 37(12): 2381-2388, 2023-This study aimed to determine if blood flow restriction (BFR) could augment adaptations to a high-load training protocol that was inadequate for muscle growth. Forty nontrained individuals had each arm assigned to 1 of 3 elbow flexion protocols: (a) high-load resistance training [TRAD; 4 sets to muscular failure at 70% 1 repetition maximum (1RM)], (b) low repetition high-load resistance training with pre-exercise BFR (PreBFR; 4 sets of 3 repetitions at 70% 1RM + 3 min of pre-exercise BFR), and (c) low repetition high-load resistance training (LRTRAD); 4 sets of 3 repetitions at 70% 1RM). Muscle thickness (MT), 1RM strength, and local muscular endurance (LME) of the elbow flexors were measured before and after 8 weeks. An alpha level of 0.05 was used for all comparisons. For the 50% site, MT increased for TRAD (0.211 cm, 95% confidence interval [95% CI]: 0.143-0.280), PreBFR (0.105 cm, 95% CI: 0.034-0.175), and LRTRAD (0.073 cm, 95% CI: 0.000-0.146). The change for TRAD was greater than PreBFR and LRTRAD. For the 60% site, MT increased for TRAD (0.235 cm, 95% CI: 0.153-0.317), PreBFR (0.097 cm, 95% CI: 0.014-0.180), and LRTRAD (0.082 cm, 95% CI: 0.000-0.164). The change for TRAD was greater than PreBFR and LRTRAD. For the 70% site MT increased for TRAD (0.308 cm, 95% CI: 0.247-0.369), PreBFR (0.103 cm, 95% CI: 0.041-0.166), and LRTRAD (0.070 cm, 95% CI: 0.004-0.137). The change for TRAD was greater than PreBFR and LRTRAD. One repetition maximum and LME significantly increased for each condition, with no differences between conditions. Collapsed across conditions 1RM strength increased 2.094 kg (95% CI: 1.771-2.416) and LME increased 7.0 repetitions (95% CI: 5.7-8.3). In conclusion, the application of BFR to low-repetition, high-load training did not enhance the adaptative response.
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Corrigendum: A narrative review of the effects of blood flow restriction on vascular structure and function. Physiol Int 2023; 110:87-88. [PMID: 36705676 DOI: 10.1556/2060.2022.10223] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2022] [Accepted: 11/08/2022] [Indexed: 01/28/2023]
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Does muscle growth mediate changes in a nonspecific strength task? Clin Physiol Funct Imaging 2023. [PMID: 36647320 DOI: 10.1111/cpf.12810] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2022] [Revised: 01/06/2023] [Accepted: 01/11/2023] [Indexed: 01/18/2023]
Abstract
The purpose of this study was to determine if muscle growth mediates increases in a strength task which was not directly trained. One hundred fifty-one participants were randomized into control, one-repetition maximum training (1RM-TRAIN), or traditional training (TRAD-TRAIN). Training groups performed isotonic elbow flexion 3x/week for 6 weeks. Anterior muscle thickness at 50%, 60% and 70% upper arm length, and maximal isokinetic torque at 60°/sec were assessed pre- and post-training. Change-score mediation models (adjusted for sex, pre-muscle thickness, and pre-strength) were constructed for each muscle thickness site. The effects of each training group were evaluated relative to the control. Data is presented as coefficient (95% CI). There were no significant relative direct effects on nonspecific strength for either training group outside of the 60% model (1.7 [0.13, 3.27] Nm). The relative effect of 1RM-TRAIN on muscle thickness was greater in 60% (0.09 [0.01, 0.17] cm) and 70% (0.09 [0.00, 0.17] cm) models; while TRAD-TRAIN was greater in all three: (50% = 0.24 [0.15, 0.32]; 60% = 0.24 [0.16, 0.33]; 70% = 0.22 [0.14, 0.31] cm). The effect of muscle thickness on nonspecific strength was only significant for the 60% (-3.06 [-5.7, -0.35] Nm) model. The relative indirect effect on nonspecific strength was not significant for the 1RM-TRAIN or TRAD-TRAIN. Similar to previous findings on specific strength, we did not find evidence for a mediating effect of muscle growth on training induced increases in nonspecific strength. The importance of muscle growth for changes in nonspecifically trained strength may need to be reconsidered.
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Does performing resistance exercise to failure homogenize the training stimulus by accounting for differences in local muscular endurance? Eur J Sport Sci 2023; 23:82-91. [PMID: 35200101 DOI: 10.1080/17461391.2021.2023657] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
The prescription of resistance exercise often involves administering a set number of repetitions to be completed at a given relative load. While this accounts for individual differences in strength, it neglects to account for differences in local muscle endurance and may result in varied responses across individuals. One way of potentially creating a more homogenous stimulus across individuals involves performing resistance exercise to volitional failure, but this has not been tested and was the purpose of the present study. Individuals completed 2 testing sessions to compare repetitions, ratings of perceived exertion (RPE), muscle swelling and fatigue responses to arbitrary repetition (SET) vs. failure (FAIL) protocols using either 60% or 30% one-repetition maximum. Statistical analyses assessed differences in the variability between protocols. Forty-six individuals (25 females and 21 males) completed the study. There was more variability in the number of repetitions completed during FAIL when compared to SET protocols. Performing the 60% 1RM condition to failure appeared to reduce the variability in muscle swelling (average variance: 60%-SET = .034, 60%-FAIL = .023) and RPE (average variance: 60%-SET = 4.0, 60%-FAIL = 2.5), but did not alter the variability in muscle fatigue. No differences in variability were present between the SET-30% and FAIL-30% protocols for any of the dependent variables. Performing resistance exercise to failure may result in a more homogenous stimulus across individuals, particularly when using moderate to high exercise loads. The prescription of resistance exercise should account for individual differences in local muscle endurance to ensure a similarly effective stimulus across individuals.Highlights There is a large variance in the number of repetitions individuals can complete even when exercising with the same relative load.Ratings of perceived exertion and muscle swelling responses become more homogenous when exercising to volitional failure as compared to using performing a set number of repetitions, particularly when moderate to higher loads are used.The prescription of exercise should take into consideration the individual's local muscle endurance as opposed to choosing an arbitrary number of repetitions to be completed at a given relative load.
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Comparing The Exercise Response And Immediate Recovery Between Two Different Blood Flow Restriction Devices. Med Sci Sports Exerc 2022. [DOI: 10.1249/01.mss.0000879976.79354.d6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Whole Body Vibration And Blood Flow Restriction For Muscle Recovery Following Exercise-induced Muscle Damage. Med Sci Sports Exerc 2022. [DOI: 10.1249/01.mss.0000879984.25767.b3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Effects Of Caffeine Abstinence On The Acute Response To Low-load Blood Flow Restriction Exercise. Med Sci Sports Exerc 2022. [DOI: 10.1249/01.mss.0000879908.57487.b9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Do Changes In Muscle Size Mediate Changes In Non-specific Strength? Med Sci Sports Exerc 2022. [DOI: 10.1249/01.mss.0000879884.76203.34] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Caffeine Abstinence In Habituated Users: Cardiovascular And Perceptual Responses To Exercise With Blood Flow Restriction. Med Sci Sports Exerc 2022. [DOI: 10.1249/01.mss.0000875428.10494.b2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Comparing The Resting Cardiovascular Response To Commonly Used Blood Flow Restriction Devices. Med Sci Sports Exerc 2022. [DOI: 10.1249/01.mss.0000879444.17207.67] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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A narrative review of the effects of blood flow restriction on vascular structure and function. Physiol Int 2022; 109:186-203. [PMID: 35587387 DOI: 10.1556/2060.2022.00223] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2021] [Revised: 03/10/2022] [Accepted: 03/22/2022] [Indexed: 11/19/2022]
Abstract
Blood flow restriction is growing in popularity as a tool for increasing muscular size and strength. Currently, guidelines exist for using blood flow restriction alone and in combination with endurance and resistance exercise. However, only about 1.3% of practitioners familiar with blood flow restriction applications have utilized it for vascular changes, suggesting many of the guidelines are based on skeletal muscle outcomes. Thus, this narrative review is intended to explore the literature available in which blood flow restriction, or a similar application, assess the changes in vascular structure or function. Based on the literature, there is a knowledge gap in how applying blood flow restriction with relative pressures may alter the vasculature when applied alone, with endurance exercise, and with resistance exercise. In many instances, the application of blood flow restriction was not in accordance with the current guidelines, making it difficult to draw definitive conclusions as to how the vascular system would be affected. Additionally, several studies report no change in vascular structure or function, but few studies look at variables for both outcomes. By examining outcomes for both structure and function, investigators would be able to generate recommendations for the use of blood flow restriction to improve vascular structure and/or function in the future.
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A comparison of variability between absolute and relative blood flow restriction pressures. Clin Physiol Funct Imaging 2022; 42:278-285. [PMID: 35396926 DOI: 10.1111/cpf.12757] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2021] [Accepted: 04/06/2022] [Indexed: 11/30/2022]
Abstract
Recommendations are that blood flow restriction (BFR) be applied relative to arterial occlusion pressure (AOP) to provide a similar stimulus. PURPOSE Compare variability of the change in blood flow, shear rate, and discomfort between recommended relative pressures and an absolute pressure. METHODS During one visit, brachial arterial blood flow was measured in 91 participants using pulse-wave Doppler ultrasonography. After 5-min seated rest, AOP was measured. Following another 5-min rest, blood flow and discomfort were assessed twice before cuff inflation as controls (C1 and C2), then again with a cuff inflated to each BFR pressure (all measures separated by 1-min). Change scores from C1 to all subsequent measures were calculated (i.e., C2-C1; 40%AOP-C1; 80%AOP-C1; 100mmHg-C1). Variability of the changes were compared via pairwise modified Pitman-Morgan tests (α=.008). RESULTS Variance (95%CI) of the change for blood flow (mL/min), shear rate (1/sec), and discomfort (AU) had similar trends. C2-C1 differed from all conditions (all p<.001), 40%AOP-C1 differed from 80%AOP-C1 and 100mmHg-C1 (all p<.001), which did not differ (both p≥.117). Blood flow: C2-C1=469.79 (357.90, 644.07), 40%AOP-C1=1263.18 (962.34, 1731.80), 80%AOP-C1=1752.90 (1335.42, 2403.18), 100mmHg-C1=1603.18 (1221.36, 2197.92); Shear rate: C2-C1=6248.24 (4760.10, 8566.15), 40%AOP-C1=14625.30 (11142.06, 20050.95), 80%AOP-C1=22064.02 (16809.13, 30249.27), 100mmHg-C1=20778.76 (15829.98, 28487.21); Discomfort: C2-C1=0.07 (0.05, 0.08), 40%AOP-C1=2.03 (1.55, 2.78), 80%AOP-C1=4.26 (3.25, 5.84), 100mmHg-C1=4.50 (3.43, 6.17). CONCLUSION Contrary to previous suggestions, applying relative pressures does not necessarily guarantee a similar stimulus. It seems that higher pressures produce more variable changes even if the external pressure applied is made relative to each individual. This article is protected by copyright. All rights reserved.
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Applying Relative And Absolute Blood Flow Restriction Alters Blood Flow Velocity But Not Blood Profiles. Med Sci Sports Exerc 2021. [DOI: 10.1249/01.mss.0000760196.35540.67] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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The Influence Of Limb Blood Flow On Muscle Growth With Different Resistance Training Protocols. Med Sci Sports Exerc 2021. [DOI: 10.1249/01.mss.0000760304.27342.99] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Blood Flow Restriction Stimulus Differs Between Absolute And Relative Pressures. Med Sci Sports Exerc 2021. [DOI: 10.1249/01.mss.0000760192.31597.fe] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Mechanisms Mediating Increased Endurance Following High- And Low-load Training With And Without Blood Flow Restriction. Med Sci Sports Exerc 2021. [DOI: 10.1249/01.mss.0000760384.50198.df] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Unilateral, bilateral, and alternating muscle actions elicit similar muscular responses during low load blood flow restriction exercise. Eur J Appl Physiol 2021; 121:2879-2891. [PMID: 34191094 DOI: 10.1007/s00421-021-04757-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2020] [Accepted: 06/20/2021] [Indexed: 11/30/2022]
Abstract
PURPOSE Compare acute muscular responses to unilateral, bilateral, and alternating blood flow restriction (BFR) exercise. METHODS Maximal strength was tested on visit one. On visits 2-4, 2-10 days apart, 19 participants completed 4 sets of knee extensions (30% one-repetition maximum) with BFR (40% arterial occlusion pressure) to momentary failure (inability to lift load) using each muscle action (counterbalanced order). Ultrasound muscle thickness was measured at 60% and 70% of the anterior thigh before (Pre), immediately (Post-0), and 5 min (Post-5) after exercise. Surface electromyography and tissue deoxygenation were measured throughout. Results, presented as means, were analyzed with a three-way (sex by time by condition) Bayesian RMANOVA. RESULTS There was a time by sex interaction (BFinclusion: 5.489) for left leg 60% muscle thickness (cm). However, changes from Pre to Post-0 (males: 0.39 vs females: 0.26; BF10: 0.839), Post-0 to Post-5 (males: - 0.05 vs females: - 0.06; BF10: 0.456), and Pre to Post-5 (males: 0.34 vs females: 0.20; BF10: 0.935) did not differ across sex. For electromyography (%MVC), there was a sex by condition interaction (BFinclusion: 550.472) with alternating having higher muscle excitation for females (16) than males (9; BF10: 5.097). Tissue deoxygenation (e.g. channel 1, µM) increased more for males (sets 1: 11.17; 2: 2.91; 3: 3.69; 4: 3.38) than females (sets 1: 4.49; 2: 0.24; 3: - 0.10; 4: - 0.06) from beginning to end of sets (all BFinclusion ≥ 4.295e + 7). For repetitions, there was an interaction (BFinclusion: 17.533), with alternating completing more than bilateral and unilateral for set one (100; 56; 50, respectively) and two (34; 16; 18, respectively). CONCLUSION Alternating, bilateral, and unilateral BFR exercise elicit similar acute muscular responses.
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Validity of the Handheld Doppler to Determine Lower-Limb Blood Flow Restriction Pressure for Exercise Protocols. J Strength Cond Res 2021; 34:2693-2696. [PMID: 29912080 DOI: 10.1519/jsc.0000000000002665] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Laurentino, GC, Loenneke, JP, Mouser, JG, Buckner, SL, Counts, BR, Dankel, SJ, Jessee, MB, Mattocks, KT, Iared, W, Tavares, LD, Teixeira, EL, and Tricoli, V. Validity of the handheld Doppler to determine lower-limb blood flow restriction pressure for exercise protocols. J Strength Cond Res 34(9): 2693-2696, 2020-Handheld (HH) Doppler is frequently used for determining the arterial occlusion pressure during blood flow restriction exercises; however, it is unknown whether the blood flow is occluded when the auscultatory signal is no longer present. The purpose of this study was to assess the validity between the HH Doppler and the Doppler ultrasound (US) measurements for determining the arterial occlusion pressure in healthy men. Thirty-five participants underwent 2 arterial occlusion pressure measurements. In the first measure, a pressure cuff (17.5 cm wide) was placed at the most proximal region of the thigh and the pulse of posterior tibial artery was detected using an HH Doppler probe. The cuff was inflated until the auscultatory pulse was no longer detected. After 10 minutes of rest, the procedure was repeated with the Doppler US probe placed on the superficial femoral artery. The cuff was inflated up to the point at which the femoral arterial blood flow was interrupted. The point at which the auscultatory pulse and blood flow were no longer detected was deemed the arterial occlusion pressure. There were no significant differences in arterial occlusion pressure level between the HH Doppler and the Doppler US (133 [±18] vs. 135 [±17] mm Hg, p = 0.168). There was a significant correlation (r = 0.938, p = 0.168), reasonable agreement, and a total error of the estimate of 6.0 mm Hg between measurements. Arterial occlusion pressure level determined by the HH Doppler and the Doppler US was similar, providing evidence that the HH Doppler is a valid and practical method.
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The Basics of Training for Muscle Size and Strength: A Brief Review on the Theory. Med Sci Sports Exerc 2020; 52:645-653. [PMID: 31652235 DOI: 10.1249/mss.0000000000002171] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The periodization of resistance exercise is often touted as the most effective strategy for optimizing muscle size and strength adaptations. This narrative persists despite a lack of experimental evidence to demonstrate its superiority. In addition, the general adaptation syndrome, which provides the theoretical framework underlying periodization, does not appear to provide a strong physiological rationale that periodization is necessary. Hans Selye conducted a series of rodent studies which used toxic stressors to facilitate the development of the general adaptation syndrome. To our knowledge, normal exercise in humans has never been shown to produce a general adaptation syndrome. We question whether there is any physiological rationale that a periodized training approach would facilitate greater adaptations compared with nonperiodized approaches employing progressive overload. The purpose of this article is to briefly review currently debated topics within strength and conditioning and provide some practical insight regarding the implications these reevaluations of the literature may have for resistance exercise and periodization. In addition, we provide some suggestions for the continued advancement within the field of strength and conditioning.
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The Impact of Ultrasound Probe Tilt on Muscle Thickness and Echo-Intensity: A Cross-Sectional Study. J Clin Densitom 2020; 23:630-638. [PMID: 30454951 DOI: 10.1016/j.jocd.2018.10.003] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/31/2018] [Revised: 10/19/2018] [Accepted: 10/22/2018] [Indexed: 11/28/2022]
Abstract
INTRODUCTION/BACKGROUND To determine the influence of ultrasound probe tilt on reliability and overall changes in muscle thickness and echo-intensity. MATERIALS AND METHODS Thirty-six individuals had a total of 15 images taken on both the biceps brachii and tibialis anterior muscles. These images were taken in 2° increments with the probe tilted either upward (U) or downward (D) from perpendicular (0°) to the muscle (U6°, U4°, U2°, 0°, D2°, D4°, and D6°). All images were then saved, stored, and analyzed using Image-J software for echo-intensity and muscle thickness measures. Mean values (2-3 measurements within each probe angle) were compared across each probe angle, and reliability was assessed as if the first measure was taken perpendicular to the muscle, but the second measure was taken with the probe tilted to a different angle (to assume unintentional adjustments in reliability from probe tilt). RESULTS Tilting the probe as little as 2° produced a significant 4.7%, and 10.5% decrease in echo-intensity of the tibialis anterior and biceps brachii muscles, respectively, while changes in muscle thickness were negligible (<1%) at all probe angles. The reliability for muscle thickness was greater than that of echo-intensity when the probe was held perpendicular at both measurements (∼1% vs 3%), and the impact that probe tilt had on reliability was exacerbated for echo-intensity measurements (max coefficient of variation: 24.5%) compared to muscle thickness (max coefficient of variation: 1.5%). CONCLUSION While muscle thickness is less sensitive to ultrasound probe tilt, caution should be taken to ensure minimal probe tilt is present when taking echo-intensity measurements as this will alter mean values and reduce reliability. Echo-intensity values should be interpreted cautiously, particularly when comparing values across technicians/studies where greater alterations in probe tilt is likely.
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Muscle Thickness Changes Do Not Mediate Changes In Muscle Strength. Med Sci Sports Exerc 2020. [DOI: 10.1249/01.mss.0000684428.05183.64] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Cardiovascular Response To Unilateral, Bilateral, And Alternating Exercises With Blood Flow Restriction. Med Sci Sports Exerc 2020. [DOI: 10.1249/01.mss.0000685184.24572.de] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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The Acute Muscular Response To Passive Movement And Blood Flow Restriction. Med Sci Sports Exerc 2020. [DOI: 10.1249/01.mss.0000685588.55876.b5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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The acute muscular response to passive movement and blood flow restriction. Clin Physiol Funct Imaging 2020; 40:351-359. [PMID: 32511829 DOI: 10.1111/cpf.12649] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2020] [Revised: 05/01/2020] [Accepted: 05/28/2020] [Indexed: 11/28/2022]
Abstract
PURPOSE To compare the acute effects of passive movement combined with blood flow restriction (PM + BFR) to passive movement (PM) or blood flow restriction alone (BFR). METHODS A total of 20 healthy participants completed: time control (TC), PM, BFR and PM + BFR (one per leg, over 2 days; randomized). For PM, a dynamometer moved the leg through 3 sets of 15 knee extensions/flexions (90° at 45°/second). For BFR, a cuff was inflated to 80% arterial occlusion pressure on the upper leg. Measurements consisted of anterior muscle thickness at 60% and 70% of the upper leg before and after (-0, -5 and -10 min) conditions, ratings of perceived effort and discomfort before conditions and after each set, and of the vastus lateralis during conditions. Data, presented as mean (SD), were compared using Bayesian RMANOVA, except for perceived effort and discomfort, which were compared using a Friedman's test (non-parametric). RESULTS 60% (Δcm before-after-0: TC = 0.04 [0.09], PM = -0.01 [0.15], BFR = 0.00 [0.11], PM + BFR = 0.01 [0.22]) and 70% (Δcm before-after-0: TC = 0.01 [0.09], PM = -0.01 [0.15], BFR = 0.02 [0.11], PM + BFR = -0.03 [0.22]) muscle thickness did not change. Perceived effort was greater than TC following PM (p = .05) and PM + BFR (p = .001). Perceived discomfort was greater following BFR and PM + BFR compared to TC (all p ≤ .002) and PM (all p ≤ .010). Changes in deoxygenation (e.g. channel 1; ΔμM start set 1-end set 3: TC = 0.9 [1.2], PM = -1.2 [1.9], BFR = 10.3 [2.7], PM + BFR = 10.3 [3.0]) were generally greater with BFR and PM + BFR (BFinclusion = 1.210e + 13). CONCLUSION Acute muscular responses to PM + BFR are not augmented over the effect of BFR alone.
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Limb Occlusion Pressure: A Method to Assess Changes in Systolic Blood Pressure. INTERNATIONAL JOURNAL OF EXERCISE SCIENCE 2020; 13:366-373. [PMID: 32148622 PMCID: PMC7039480] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Although often used as a surrogate, comparisons between traditional blood pressure measurements and limb occlusion assessed via hand-held Doppler have yet to be completed. Using limb occlusion pressure as a method of assessing systolic pressure is of interest to those studying the acute effects of blood flow restriction, where the removal of the cuff may alter the physiological response. PURPOSE We sought to determine how changes in limb occlusion pressure track with changes in traditional assessments of blood pressure. BASIC PROCEDURES Limb occlusion pressure measured by hand-held Doppler and blood pressure measured by an automatic blood pressure cuff were assessed at rest and following isometric knee extension (post and 5 minutes post). MAIN FINDINGS Each individual had a similar dispersion from the mean value for both the limb occlusion pressure measurement and traditional systolic blood pressure measurement [BF10: 0.33; median (95% credible interval): 0.02 (-6.0, 5.9) %]. In response to lower body isometric exercise, blood pressure changed across time. The difference between measurements was small at immediately post and 5 minutes post. The Bayes factors were in the direction of the null but did not exceed the threshold needed to accept the null hypothesis. However, at 5 minutes post, the differences were within the range of practical equivalence (within ± 4.6%). PRINCIPAL CONCLUSIONS Our findings suggest that changes in limb occlusion pressure measured by hand-held Doppler track similarly to traditional measurements of brachial systolic blood pressure following isometric knee extension exercise.
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A comparison of acute changes in muscle thickness between A-mode and B-mode ultrasound. Physiol Meas 2019; 40:115004. [PMID: 31631884 DOI: 10.1088/1361-6579/ab4f14] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
OBJECTIVE The purpose of this study was to compare acute changes in muscle thickness (MT) between A-mode and B-mode ultrasound before and after four sets of biceps curls. APPROACH Participants visited the laboratory on two separate occasions. The first visit consisted of paperwork and one repetition maximum (1RM) strength assessment. During the second visit, participants performed four sets of biceps curls to volitional failure using an exercise load equal to 70% of 1RM or a time-matched non-exercise control. MT measurements were taken before and immediately after exercise. MT measures were taken using both A-mode and B-mode ultrasound. MAIN RESULTS Results are displayed as mean (SD). A total of 49 resistance-trained men (n = 24) and women (n = 25) completed the study. There was no group (experimental versus control) by mode (A-mode versus B-mode) by time interaction (p = 0.442). However, there was a group (experimental versus control) × time (pre versus post) interaction (p < 0.001). Muscle thickness increased from pre (3.61 (0.86) cm) to post exercise (4.06 (0.92) cm) in the experimental group (p < 0.001). However, there was no change from pre (3.46 (0.78) cm) to post (3.48 (0.78) cm) in the time-matched control group (p = 0.237). There was a main effect for ultrasound mode (A-mode versus B-mode) (p < 0.001). Muscle thickness values as measured by A-mode ultrasound were lower than those measured by B-mode ultrasound pre (A-mode = 3.43 (0.79) cm versus B-mode = 3.63 (0.84) cm) and post (A-mode = 3.67 (0.87) cm versus B-mode = 3.83 (0.91) cm) intervention. SIGNIFICANCE MT measurements taken using A-mode ultrasound are lower than those of B-mode ultrasound. Despite this difference, it appears A-mode can detect similar acute changes in MT following resistance exercise when compared to B-mode ultrasound. These results suggest that A-mode ultrasound can serve as a useful tool when examining acute changes in MT.
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Assessing differential responders and mean changes in muscle size, strength, and the crossover effect to 2 distinct resistance training protocols. Appl Physiol Nutr Metab 2019; 45:463-470. [PMID: 31553889 DOI: 10.1139/apnm-2019-0470] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The objective of this study was to determine differences in 2 distinct resistance training protocols and if true variability can be detected after accounting for random error. Individuals (n = 151) were randomly assigned to 1 of 3 groups: (i) a traditional exercise group performing 4 sets to failure; (ii) a group performing a 1-repetition maximum (1RM) test; and (iii) a time-matched nonexercise control group. Both exercise groups performed 18 sessions of elbow flexion exercise over 6 weeks. While both training groups increased 1RM strength similarly (∼2.4 kg), true variability was only present in the traditional exercise group (true variability = 1.80 kg). Only the 1RM group increased untrained arm 1RM strength (1.5 kg), while only the traditional group increased ultrasound measured muscle thickness (∼0.23 cm). Despite these mean increases, no true variability was present for untrained arm strength or muscle hypertrophy in either training group. In conclusion, these findings demonstrate the importance of taking into consideration the magnitude of random error when classifying differential responders, as many studies may be classifying high and low responders as those who have the greatest amount of random error present. Additionally, our mean results demonstrate that strength is largely driven by task specificity, and the crossover effect of strength may be load dependent. Novelty Many studies examining differential responders to exercise do not account for random error. True variability was present in 1RM strength gains, but the variability in muscle hypertrophy and isokinetic strength changes could not be distinguished from random error. The crossover effect of strength may differ based on the protocol employed.
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Blood flow restriction does not augment low force contractions taken to or near task failure. Eur J Sport Sci 2019; 20:650-659. [DOI: 10.1080/17461391.2019.1664640] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
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Blood flow restriction augments the skeletal muscle response during very low-load resistance exercise to volitional failure. Physiol Int 2019; 106:180-193. [PMID: 31262205 DOI: 10.1556/2060.106.2019.15] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The purpose of this study was to compare the acute muscular response with resistance exercise between the following conditions [labeled (% one-repetition maximum/% arterial occlusion pressure)]: high-load (70/0), very low-load (15/0), very low-load with moderate (15/40), and high (15/80) blood flow restriction pressures. Twenty-three participants completed four sets of unilateral knee extension to failure (up to 90 repetitions) with each condition, one condition per leg, each day. Muscle thickness and maximal voluntary contraction (MVC) were measured before (Pre), immediately after (Post-0), and 15 min after (Post-15) exercise and electromyography (EMG) amplitude during exercise. Pre to Post-0 muscle thickness changes in cm [95% CI] were greater with 15/40 [0.57 (0.41, 0.73)] and 15/80 [0.49 (0.35, 0.62)] compared to 70/0 [0.33 (0.25, 0.40)]. Pre to Post-0 MVC changes in Nm [95% CI] were higher with 15/40 [-127.0 (-162.1, -91.9)] and 15/80 [-133.6 (-162.8, -104.4)] compared to 70/0 [-48.4 (-70.1, -26.6)] and 15/0 [-98.4 (-121.9, -74.9)], which were also different. Over the first three repetitions, EMG increased across sets, whereas in the last three repetitions it did not. EMG was also different between conditions and was generally greater during 70/0. Repetitions decreased across sets reaching the lowest for 70/0, and for very low loads decreased with increased pressure. In trained participants exercising to failure, lower load and the application of restriction pressure augment changes in muscle thickness and torque. The EMG amplitude was augmented by load. Training studies should compare these conditions, as the results herein suggest some muscular adaptations may differ.
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Endurance is Augmented By Greater Blood Flow Restriction Pressures: Muscle Size and Strength Are Not. Med Sci Sports Exerc 2019. [DOI: 10.1249/01.mss.0000563413.04706.28] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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High Pressure Blood Flow Restriction Is Necessary For Peripheral Vascular Adaptations With Very Low Loads. Med Sci Sports Exerc 2019. [DOI: 10.1249/01.mss.0000562469.79288.e2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Blood Flow Restriction Does Not Augment Low Force Contractions Taken to or Near Task Failure. Med Sci Sports Exerc 2019. [DOI: 10.1249/01.mss.0000563411.27576.b4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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High Blood Flow Restriction Pressure is Necessary to Induce Vascular Adaptations with Very Low-Load Training. Med Sci Sports Exerc 2019. [DOI: 10.1249/01.mss.0000562468.02160.19] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Arm Circumference As A Method To Standardize The Practical Blood Flow Restriction Pressure. Med Sci Sports Exerc 2019. [DOI: 10.1249/01.mss.0000560894.76382.57] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Abstract
The purpose was to examine changes in the perceptual responses to lifting a very low load (15% one repetition maximum (1RM)) with and without (15/0) different pressures [40% (15/40) and 80% (15/80) arterial occlusion pressure] and compare that to traditional high load (70/0) resistance exercise. Ratings of perceived exertion (RPE) and discomfort were measured following each set of exercise. In addition, resting arterial occlusion pressure was measured prior to exercise. Assessments were made in training sessions 1, 9, and 16 for the upper and lower body. Data are presented as means and 95% CI. There were changes in RPE in the upper body with condition 15/40 [-2.1 (-3.4, -0.850)] and 15/80 [-2.4 (-3.6, -1.1)] decreasing by the end of training. In the lower body, RPE decreased in condition 15/40 [-1.4 (-2.3, -0.431)] by the end of the training study. There was a main effect of time in the upper body with all conditions decreasing discomfort. In the lower body, all conditions decreased except for 15/80. For arterial occlusion pressure, there were differences across time in the 15/40 condition and the 15/80 condition in the upper body. Repeated exposure to blood flow restriction may dampen the perceptual responses over time.
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High-pressure blood flow restriction with very low load resistance training results in peripheral vascular adaptations similar to heavy resistance training. Physiol Meas 2019; 40:035003. [DOI: 10.1088/1361-6579/ab0d2a] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Is muscle growth a mechanism for increasing strength? Med Hypotheses 2019; 125:51-56. [DOI: 10.1016/j.mehy.2019.02.030] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2018] [Revised: 02/07/2019] [Accepted: 02/09/2019] [Indexed: 11/24/2022]
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Acute hemodynamic changes following high load and very low load lower body resistance exercise with and without the restriction of blood flow. Physiol Meas 2018; 39:125007. [DOI: 10.1088/1361-6579/aaefc9] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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A method to standardize the blood flow restriction pressure by an elastic cuff. Scand J Med Sci Sports 2018; 29:329-335. [PMID: 30468528 DOI: 10.1111/sms.13340] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2018] [Revised: 10/22/2018] [Accepted: 11/19/2018] [Indexed: 11/30/2022]
Abstract
Blood flow restriction training using a practical (non-pneumatic) elastic cuff has recently increased in popularity. However, a criticism of this method is that the pressure applied and the amount of blood flow restriction induced is unknown. The aim was to quantify blood flow following the application of an elastic cuff and compare that to what is observed using a more traditional pressurized nylon cuff. Thirty-five young participants (16 men and 19 women) visited the laboratory once for testing. In a randomized order (one condition per arm), an elastic cuff (5 cm wide) was applied to one arm and blood flow was measured following the cuff being pulled to two distinct lengths; 10% and 20% of the resting length based on arm circumference. The other arm would follow a similar protocol but use a pressurized nylon cuff (5 cm wide) and be inflated to 40% and 80% of the individuals resting arterial occlusion pressure. There was a main effect of pressure for blood flow with it decreasing in a pressure-dependent manner (High < Low, P < 0.001). The mean difference (95% CI) in blood flow between cuffs was -5.9 (-18.9, 7.0) % for the lower pressure and -4.0 (-13.2, 5.1) % for the higher pressure. When the relative changes for each cuff were separated by sex, there were no differences in the changes from Pre (P ≥ 0.509). The application of a pressure relative to the initial belt length, which is largely dependent upon arm circumference, appears to provide one method to standardize the practical blood flow restriction pressure for future research.
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Acute skeletal muscle responses to very low-load resistance exercise with and without the application of blood flow restriction in the upper body. Clin Physiol Funct Imaging 2018; 39:201-208. [PMID: 30506882 DOI: 10.1111/cpf.12557] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2018] [Accepted: 11/06/2018] [Indexed: 01/08/2023]
Abstract
The purpose was to examine the acute skeletal muscle response to high load exercise and low-load exercise with and without different levels of applied pressure (BFR). A total of 22 participants completed the following four conditions: elbow flexion exercise to failure using a traditional high load [70% 1RM, (7000)], low load [15% 1RM,(1500)], low load with moderate BFR [15%1RM+40%BFR(1540)] or low load with greater BFR [15% 1RM+80%BFR(1580)]. Torque and muscle thickness were measured prior to, immediately post, and 15 min postexercise. Muscle electromyography (EMG) amplitude was measured throughout. Immediately following exercise, the 7000 condition had lower muscle thickness [4·2(1·0)cm] compared to the 1500 [4·4 (1·1)cm], 1540 [4·4(1·1)cm] and 1580 [4·5(1·0)cm] conditions. This continued 15 min post. Immediately following exercise, torque was lower in the 1500 [31·8 (20) Nm], 1540 [28·3(16·9) Nm, P<0·001] and 1580 [29·5 (17) Nm] conditions compared to the 7000 condition [40 (19) Nm]. Fifteen minutes post, 1500 and 1540 conditions demonstrated lower torque compared to the 7000 condition. For the last three repetitions percentage EMG was greater in the 7000 compared to the 1580 condition. Very low-load exercise (with or without BFR) appears to result in greater acute muscle swelling and greater muscular fatigue compared to high load exercise.
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Effects of load on the acute response of muscles proximal and distal to blood flow restriction. J Physiol Sci 2018; 68:769-779. [PMID: 29349721 PMCID: PMC10717311 DOI: 10.1007/s12576-018-0593-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2017] [Accepted: 01/10/2018] [Indexed: 01/10/2023]
Abstract
To determine the effects of load and blood flow restriction (BFR) on muscular responses, we asked 12 participants to perform chest presses under four different conditions [30/0, 30/40, 50/0, and 50/40, presented as percentage one-repetition maximum (1RM)/percentage arterial occlusion pressure (AOP)]. Muscle thickness increased pre- to post-exercise [chest: mean 0.29, 95% confidence interval (CI) 0.21, 0.37 cm; triceps: mean 0.44, 95% CI 0.34, 0.54 cm], remaining elevated for 15 min post-exercise. Electromyography amplitude was greater with 50% 1RM and increased over time for the first three repetitions of each set of chest presses. The last three repetitions differed across time only. AOP increased from pre- to post-exercise, augmented by BFR [30/0: mean 31, 95% CI 18, 44 mmHg; 30/40: mean 39, 95% CI 28, 50 mmHg; 50/0: mean 32, 95% CI 23, 41 mmHg; 50/40: mean 46, 95% CI 32, 59 mmHg). Tranquility decreased and physical exhaustion increased from the pre- to post-condition, with both parameters returning to the baseline 15 min post-exercise level. In conclusion, load and BFR do not elicit meaningful differences in the acute response of chest press exercise taken to failure.
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Arterial occlusion pressure as a method to quantify cardiovascular responses to exercise. Biomed Phys Eng Express 2018. [DOI: 10.1088/2057-1976/aae8c2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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An investigation into setting the blood flow restriction pressure based on perception of tightness. Physiol Meas 2018; 39:105006. [PMID: 30211696 DOI: 10.1088/1361-6579/aae140] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
OBJECTIVE To determine whether the perceived tightness scale could be used to set sub-occlusive blood flow restriction pressures. A secondary aim was to determine variables that may impact individual ratings. APPROACH One hundred and twenty participants completed three separate conditions in one limb within the upper and lower body. Participants were asked to rate their perceived tightness for two of the three conditions, regarded as moderate pressure without pain (7/10) and intense pressure with pain (10/10). A third condition, arterial occlusion pressure, was completed that required no rating from participants. Order of conditions and limb assignment were randomized for each participant. Measurements for muscle and fat thickness along with limb circumference were completed on the tested limbs. MAIN RESULTS Order of conditions did not affect results in the upper or lower body. A condition effect was found for the upper body with the 7/10 rating lower than the arterial occlusion pressure [7/10: 132 (38) mmHg < Arterial Occlusion: 162 (24) mmHg < 10/10: 202 (46) mmHg]. A condition effect was also found for the lower body with 7/10 condition [120 (33) mmHg] rating lower than arterial occlusion pressure [171 (28) mmHg] and 10/10 condition [178 (49) mmHg]. However, there was a non-significant difference between the arterial occlusion pressure and the 10/10 condition (difference of 7(-3, 18) mmHg, (P = 0.159). SIGNIFICANCE Participants appear adept in their ability to rate sub-occlusive pressure based upon perceived tightness. Findings from this study provide some support for the utility of this method as a means for completion of practical blood flow restriction, whereby individuals tighten the cuff based upon their relative perceptual response.
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Muscle Adaptations to High-Load Training and Very Low-Load Training With and Without Blood Flow Restriction. Front Physiol 2018; 9:1448. [PMID: 30386254 PMCID: PMC6198179 DOI: 10.3389/fphys.2018.01448] [Citation(s) in RCA: 72] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2018] [Accepted: 09/24/2018] [Indexed: 11/18/2022] Open
Abstract
An inability to lift loads great enough to disrupt muscular blood flow may impair the ability to fatigue muscles, compromising the hypertrophic response. It is unknown what level of blood flow restriction (BFR) pressure, if any, is necessary to reach failure at very low-loads [i.e., 15% one-repetition maximum (1RM)]. The purpose of this study was to investigate muscular adaptations following resistance training with a very low-load alone (15/0), with moderate BFR (15/40), or with high BFR (15/80), and compare them to traditional high-load (70/0) resistance training. Using a within/between subject design, healthy young participants (n = 40) performed four sets of unilateral knee extension to failure (up to 90 repetitions/set), twice per week for 8 weeks. Data presented as mean change (95% CI). There was a condition by time interaction for 1RM (p < 0.001), which increased for 70/0 [3.15 (2.04,4.25) kg] only. A condition by time interaction (p = 0.028) revealed greater changes in endurance for 15/80 [6 (4,8) repetitions] compared to 15/0 [4 (2,6) repetitions] and 70/0 [4 (2,5) repetitions]. There was a main effect of time for isometric MVC [change = 10.51 (3.87,17.16) Nm, p = 0.002] and isokinetic MVC at 180°/s [change = 8.61 (5.54,11.68) Nm, p < 0.001], however there was no change in isokinetic MVC at 60°/s [2.45 (−1.84,6.74) Nm, p = 0.261]. Anterior and lateral muscle thickness was assessed at 30, 40, 50, and 60% of the upper leg. There was no condition by time interaction for muscle thickness sites (all p ≥ 0.313). There was a main effect of time for all sites, with increases over time (all p < 0.001). With the exception of the 30% lateral site (p = 0.059) there was also a main effect of condition (all p < 0.001). Generally, 70/0 was greater. Average weekly volume increased for all conditions across the 8 weeks, and was greatest for 70/0 followed by 15/0, 15/40, then 15/80. With the exception of 1RM, changes in strength and muscle size were similar regardless of load or restriction. The workload required to elicit these changes lowered with increased BFR pressure. These findings may be pertinent to rehabilitative settings, future research, and program design.
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Magnetic resonance imaging-measured skeletal muscle mass to fat-free mass ratio increases with increasing levels of fat-free mass. J Sports Med Phys Fitness 2018; 59:619-623. [PMID: 30264974 DOI: 10.23736/s0022-4707.18.08683-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
BACKGROUND To investigate the skeletal muscle mass to fat-free mass (SM-FFM) ratio in female and male athletes, as well as to examine the relationship between ultrasound predicted SM and magnetic resonance imaging (MRI)-measured SM. METHODS Seven female track and field athletes (female), 8 male collegiate swimmers (male-G1) and 8 male collegiate Olympic weightlifters (male-G2) volunteered. Whole-body SM volume was measured using MRI images obtained from the first cervical vertebra to the ankle joints. The volume of SM tissue was calculated and the SM volume was converted into mass units by an assumed skeletal muscle density. Muscle thickness was measured using ultrasound at nine sites and SM was estimated using an ultrasound-derived prediction equation. RESULTS Percent body fat was similar among the groups. FFM, MRI-measured SM and SM-FFM ratio were greater in Males-G2 compared to the other two groups and those variables of Male-G1 were higher than the Female group. There was an excellent correlation (r=0.976) between MRI-measured and ultrasound-predicted SM (total error=1.52 kg). No significant difference was observed between MRI-measured and ultrasound-predicted SM in the overall sample or within each group. The SM-FFM ratio was positively correlated (r=0.708) with FFM in female and male athletes. CONCLUSIONS We provide evidence for how the MRI-measured SM-FFM ratio changes with increasing levels of FFM and provide data that the ultrasound may be useful in estimating SM in athletes. Given the size limitations with MRI, both of these findings may be useful for future research investigating large sized athletes.
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Very-low-load resistance exercise in the upper body with and without blood flow restriction: cardiovascular outcomes. Appl Physiol Nutr Metab 2018; 44:288-292. [PMID: 30148969 DOI: 10.1139/apnm-2018-0325] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
It is proposed that, at very low loads, greater blood flow restriction (BFR) pressures might be required for muscular adaptation to occur. The cardiovascular and hyperemic response to very low loads combined with relative levels of BFR is unknown. Ninety-seven participants were recruited and assigned to 1 of 4 exercise conditions: 15% of 1-repetition maximum (1RM) without BFR (15/00), 15% 1RM with BFR at 40% of arterial occlusion pressure (AOP) (15/40), 15% of 1RM with BFR at 80% of AOP (15/80), and 70% of 1RM without BFR (70/00). Participants performed 4 sets of unilateral biceps curls. Blood pressure was measured before and after exercise; brachial artery blood flow was measured before exercise, following the second set, and 1 min following exercise. Systolic blood pressure increased following exercise in all conditions (+10 (11) mm Hg, P < 0.0005). Diastolic pressure increased in all but 70/00 (+2 (11) mm Hg, P = 0.107). Brachial artery blood flow increased following the second set of exercise in all but 15/80 (+43.4 (76.8) mL·min-1, P = 0.348). One minute following exercise and cuff deflation, there were no differences in blood flow between conditions (P > 0.05). Similarly, artery diameter was increased in all conditions except 15/80 (+0.002 (0.041) cm, P = 0.853) following the second set, and increased in all conditions by 1 min following exercise (P < 0.05). In conclusion, exercise-induced hyperemia is blunted with increasing pressures of BFR. There is a modest increase in blood pressure at very low loads of resistance exercise in the upper body.
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Perceptual and arterial occlusion responses to very low load blood flow restricted exercise performed to volitional failure. Clin Physiol Funct Imaging 2018; 39:29-34. [PMID: 29938892 DOI: 10.1111/cpf.12535] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2018] [Accepted: 06/06/2018] [Indexed: 12/11/2022]
Abstract
PURPOSE Studies examining perceptual and arterial occlusion responses between blood flow restricted exercise and high load exercise often prescribe an arbitrary number of repetitions, making it difficult for direct comparisons. Therefore, the purpose of this study was to compare these protocols when performed to volitional failure. METHODS Individuals completed four exercise conditions varying in load and pressure: (i) 15% 1RM; no restrictive pressure, (ii) 15% 1RM; 40% arterial occlusion pressure, (iii) 15% 1RM; 80% arterial occlusion pressure, and (iv) 70% 1RM; no pressure. Four sets of knee extension exercises were performed until volitional failure (or until 90 repetitions per set) was completed. RESULTS A total of 23 individuals completed the study. While all conditions increased arterial occlusion pressure, the greatest increases (~30%) were observed in the blood flow restriction conditions. All lower load conditions resulted in greater RPE and discomfort than that of the high load condition, but only discomfort was increased further when adding blood flow restriction. CONCLUSION High load exercise will likely be perceived more favourably than lower load exercise to volitional failure; however, those who are incapable or unwilling to lift heavier loads may use blood flow restriction to help reduce the volume needed to reach volitional failure, although this will likely increase discomfort.
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