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Abstract

The aim of the study was to determine whether the similar muscle strength and hypertrophy responses observed after either low-intensity resistance exercise associated with moderate blood flow restriction or high-intensity resistance exercise are associated with similar changes in messenger RNA (mRNA) expression of selected genes involved in myostatin (MSTN) signaling. Twenty-nine physically active male subjects were divided into three groups: low-intensity (20% one-repetition maximum (1RM)) resistance training (LI) (n = 10), low-intensity resistance exercise associated with moderate blood flow restriction (LIR) (n = 10), and high-intensity (80% 1RM) resistance exercise (HI) (n = 9). All of the groups underwent an 8-wk training program. Maximal dynamic knee extension strength (1RM), quadriceps cross-sectional area (CSA), MSTN, follistatin-like related genes (follistatin (FLST), follistatin-like 3 (FLST-3)), activin IIb, growth and differentiation factor-associated serum protein 1 (GASP-1), and MAD-related protein (SMAD-7) mRNA gene expression were assessed before and after training. Knee extension 1RM significantly increased in all groups (LI = 20.7%, LIR = 40.1%, and HI = 36.2%). CSA increased in both the LIR and HI groups (6.3% and 6.1%, respectively). MSTN mRNA expression decreased in the LIR and HI groups (45% and 41%, respectively). There were no significant changes in activin IIb (P > 0.05). FLST and FLST-3 mRNA expression increased in all groups from pre- to posttest (P < 0.001). FLST-3 expression was significantly greater in the HI when compared with the LIR and LI groups at posttest (P = 0.024 and P = 0.018, respectively). GASP-1 and SMAD-7 gene expression significantly increased in both the LIR and HI groups. We concluded that LIR was able to induce gains in 1RM and quadriceps CSA similar to those observed after traditional HI. These responses may be related to the concomitant decrease in MSTN and increase in FLST isoforms, GASP-1, and SMAD-7 mRNA gene expression.

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... Strength exercise performed with low external loading (LL, ≤50% of one-repetition maximum (1RM)) and partial (< full arterial occlusion) or full (full arterial occlusion) blood flow restriction (BFR) has been shown to be an effective training method promoting gains in neuromuscular function (e.g., maximal muscle strength) and skeletal muscle growth [1][2][3][4]. Similar gains in these parameters have been reported between LL-BFR training and conventional high-load resistance training (≥65% 1RM) [1,2], however, these findings are not universal [3]. ...
... Strength exercise performed with low external loading (LL, ≤50% of one-repetition maximum (1RM)) and partial (< full arterial occlusion) or full (full arterial occlusion) blood flow restriction (BFR) has been shown to be an effective training method promoting gains in neuromuscular function (e.g., maximal muscle strength) and skeletal muscle growth [1][2][3][4]. Similar gains in these parameters have been reported between LL-BFR training and conventional high-load resistance training (≥65% 1RM) [1,2], however, these findings are not universal [3]. ...
... Notably, the potential ability of LL-BFR to provide the same anabolic stimulus with an average or peak mechanical dose compared to LL-FF exercise [1,6], may be beneficial in several applied contexts -particularly to groups for whom high levels of mechanical stress are contraindicated (e.g., postoperative recovery). ...
Article
This paper aimed to examine the acute effect of low-load (LL) exercise with blood-flow restriction (LL-BFR) on microvascular oxygenation and muscle excitability of the vastus medialis (VM) and vastus lateralis (VL) muscles during a single bout of unilateral knee extension exercise performed to task failure. Seventeen healthy recreationally resistance-trained males were enrolled in a within-group randomized cross-over study design. Participants performed one set of unilateral knee extensions at 20% of one-repetition maximum (1RM) to task failure, using a LL-BFR or LL free-flow (LL-FF) protocol in a randomized order on separate days. Changes in oxygenation and muscle excitability in VL and VM were assessed using near-infrared spectroscopy (NIRS) and surface electromyography (sEMG), respectively. Pain measures were collected using the visual analog scale (VAS) before and following set completion. Within- and between- protocol comparisons were performed at multiple time points of set completion for each muscle. During LL-BFR, participants performed 43% fewer repetitions and reported feeling more pain compared to LL-FF (p<0.05). Normalized to time to task failure, LL-BFR and LL-FF generally demonstrated similar progression in microvascular oxygenation and muscle excitability during exercise to task failure. The present results demonstrate that LL-BFR accelerates time to task failure, compared with LL-FF, resulting in a lower dose of mechanical work to elicit similar levels of oxygenation, blood-pooling, and muscle excitability. LL-BFR may be preferable to LL-FF in clinical settings where high workloads are contraindicated, although increased pain experienced during BFR may limit its application.
... 1RM/MVC) before being deflated upon completion of the final exercise set Ellefsen et al, 2015;Laurentino et al, 2012). Other variations exist, including the use of BfR intermittently across an exercise session, or the use of BfR during high-intensity resistance training at ≥ 60% 1RM/MVC (Laurentino et al, 2008;Neto et al, 2014;Teixeira et al, 2017). ...
... Evidence points towards both LiBfRT and HiRT being able to significantly increase postintervention 1RM for knee extension (Laurentino et al, 2012;Martín-Hernández et al, 2013) and leg press Vechin et al, 2015) over training periods of four to 12 weeks. Across studies, between-group improvements in 1RM were either similar between modalities, or of a greater magnitude with HiRT. ...
... Over an eight-week programme, Laurentino et al (2012) has shown that cohort kneeextensor 1RM can increase significantly following either LiRT or LiBfRT within healthy males (p < 0.001). Participants completing LiBfRT twice-weekly experienced a larger percentage increase in pre-post 1RM than those performing LiRT twice-weekly at the same exercise intensity (mean 20.7% vs. 40.2%), ...
... Number of protocols 80 3 (Laurentino et al., 2008;Lixandrão et al., 2015;Biazon et al., 2019) 50-60 3 (Laurentino et al., 2008;Cook et al., 2017;May et al., 2018) 40 2 (Cook et al., 2017;Ruaro et al., 2019) 30 20 (Fahs et al., 2015;Cook et al., 2017;Kim et al., 2017;Letieri et al., 2018;May et al., 2018;Bemben et al., 2019;de Lemos Muller et al., 2019;Gavanda et al., 2020;Hill et al., 2020) 15-20 20 (Laurentino et al., 2012;Manimmanakorn et al., 2013;Lixandrão et al., 2015;Jessee et al., 2018;Brandner et al., 2019;Neto et al., 2019;Clarkson et al., 2020;Mendonca et al., 2021) greater improvements in the non-BFR group in exercises where the primary muscle was too proximal such as lateral pulldown and bench press. At 20% however, the non-BFR group had significantly greater strength improvements. ...
... Training at 80% 1RM with low pressure BFR (40% LOP) produced significantly worse strength improvements than controls, although comparable results with high pressure BFR (100% LOP). Both studies looking at intensities of 50-60% 1RM with BFR found similar strength improvements to high intensity non-BFR but only at very high pressure (Laurentino et al., 2012;Cook et al., 2017) (100-150% LOP). Interestingly 40% 1RM with BFR produces significantly greater strength improvements when moderate pressure was applied (70% LOP), but significantly lower strength improvements at low-moderate pressure (40% LOP). ...
... et al., 2008;Manimmanakorn et al., 2013;Cook et al., 2017;Biazon et al., 2019;de Lemos Muller et al., 2019) 8010(Laurentino et al., 2012;Lixandrão et al., 2015;Jessee et al., 2018;de Lemos Muller et al., 2019; Neto et al.May et al., 2018;Brandner et al., 2019;Gavanda et al., 2020;Mendonca et al., 2021) 50 9(Fahs et al., 2015;Vechin et al., 2015;Kim et al., 2017;Bemben et al., 2019;Centner et al., 2019) ...
Article
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Background Blood flow restriction (BFR) training at lower exercise intensities has a range of applications, allowing subjects to achieve strength and hypertrophy gains matching those training at high intensity. However, there is no clear consensus on the percentage of limb occlusion pressure [%LOP, expressed as a % of the pressure required to occlude systolic blood pressure (SBP)] and percentage of one repetition max weight (%1RM) required to achieve these results. This review aims to explore what the optimal and minimal combination of LOP and 1RM is for significant results using BFR. Method A literature search using PubMed, Scopus, Wiley Online, Springer Link, and relevant citations from review papers was performed, and articles assessed for suitability. Original studies using BFR with a resistance training exercise intervention, who chose a set %LOP and %1RM and compared to a non-BFR control were included in this review. Result Twenty-one studies met the inclusion criteria. %LOP ranged from 40 to 150%. %1RM used ranged from 15 to 80%. Training at 1RM ≤20%, or ≥ 80% did not produce significant strength results compared to controls. Applying %LOP of ≤50% and ≥ 80% did not produce significant strength improvement compared to controls. This may be due to a mechanism mediated by lactate accumulation, which is facilitated by increased training volume and a moderate exercise intensity. Conclusion Training at a minimum of 30 %1RM with BFR is required for strength gains matching non-BFR high intensity training. Moderate intensity training (40–60%1RM) with BFR may produce results exceeding non-BFR high intensity however the literature is sparse. A %LOP of 50–80% is optimal for BFR training.
... Although the long-term benefits of BFR exercise, including increased muscular size, strength, muscular endurance, muscular power, and enhanced aerobic capacity, have been extensively reported in the scientific literature (Laurentino et al., 2012;Bjørnsen et al., 2019;Wilk et al., 2020), the underlying mechanisms responsible for these adaptations generally remain speculative. One of the most often referenced occurrence that is thought to be linked to the positive adaptations of BFR exercise is the exercise-induced metabolic stress (Suga et al., 2010;Takada et al., 2012). ...
... BFR exercise has also been shown to influence the MSTN pathway, which is a down regulator of muscle growth. In this context, Laurentino et al. (2012) demonstrated that 8 weeks of BFR resistance training resulted in similar muscular size and strength gains similar to traditional high-load resistance training with concomitant decrease in MSTN gene expression. ...
... It should be noted that several modes of contraction exist to assess performances to resistance exercise which include isometric contractions (no visible movement of the limb during muscular contraction), isotonic contractions (constant force being generated throughout the entire range of motion as controlled devices like Cybex or KinCom), isokinetic contractions (constant velocity of movement throughout the entire range of motion as controlled by devices like Cybex or KinCom), or dynamic contractions with the use of free weights. In many studies, relative loads of 20 to 30% 1RM with blood flow restriction have been compared to traditional high-intensity (80% 1RM; Laurentino et al., 2008Laurentino et al., , 2012Karabulut et al., 2010) resistance training without blood flow restriction but blood flow restriction exercise loads have ranged from 20 to 50% 1RM. ...
Article
Full-text available
The use of blood flow restricted (BFR) exercise has become an accepted alternative approach to improve skeletal muscle mass and function and improve cardiovascular function in individuals that are not able to or do not wish to use traditional exercise protocols that rely on heavy loads and high training volumes. BFR exercise involves the reduction of blood flow to working skeletal muscle by applying a flexible cuff to the most proximal portions of a person’s arms or legs that results in decreased arterial flow to the exercising muscle and occluded venous return back to the central circulation. Safety concerns, especially related to the cardiovascular system, have not been consistently reported with a few exceptions; however, most researchers agree that BFR exercise can be a relatively safe technique for most people that are free from serious cardiovascular disease, as well as those with coronary artery disease, and also for people suffering from chronic conditions, such as multiple sclerosis, Parkinson’s, and osteoarthritis. Potential mechanisms to explain the benefits of BFR exercise are still mostly speculative and may require more invasive studies or the use of animal models to fully explore mechanisms of adaptation. The setting of absolute resistive pressures has evolved, from being based on an individual’s systolic blood pressure to a relative measure that is based on various percentages of the pressures needed to totally occlude blood flow in the exercising limb. However, since several other issues remain unresolved, such as the actual external loads used in combination with BFR, the type of cuff used to induce the blood flow restriction, and whether the restriction is continuous or intermittent, this paper will attempt to address these additional concerns.
... Suppression of myostatin upregulates muscle hypertrophy factors such as myoblast determination protein 1 (Myod1) and Akirin1 (Mighty) in skeletal muscle 161,162 . Serum myokine levels are also reduced by various types of exercise [163][164][165][166][167][168][169][170][171] (TAblE 3). A low-intensity aerobic exercise intervention for 6 months in middle-aged individuals (n = 10) with insulin resistance significantly reduced serum myostatin levels by 20% (P = 0.003) compared with levels before the aerobic exercise intervention 163 , and a single bout of resistance exercise significantly reduced serum myostatin levels in elderly men (n = 12) by 22.5% (P < 0.05) compared with levels before the exercise session 171 . ...
... However, myokines remain only a candidate molecular player for cancer growth inhibition owing to a lack of clinical studies. Although clinical studies have investigated the exercise-induced myokine response in non-cancer populations after acute exercise and prolonged exercise training 22,65,86,88,90,91,99,100,111,112,[114][115][116][147][148][149][150][151][152][153][163][164][165][166][167][168][169][170][222][223][224][225] , outcomes might not be applicable to patients with cancer, as patients with cancer and patients undergoing active treatment (for example, ADT) might have impaired exercise capacity and different thresholds in myokine response compared with healthy individuals, potentially owing to increased fat mass, reduced skeletal muscle mass and reduced cardiovascular capacity 235 . A lack of research investigating the relationship between myokine expression and clinical outcomes, such as disease progression and disease-related death, is another limitation of clinical studies investigating exercise and prostate cancer regression. ...
... Notably, exercise guidelines do not reflect the systemic alteration of myokines owing to a lack of studies investigating this area. Nevertheless, based on the studies investigating myokine expression in patients without cancer 22,65,86,88,90,91,99,100,111,112,[114][115][116][147][148][149][150][151][152][153][163][164][165][166][167][168][169][170][222][223][224][225] , exercise duration and volumes exceeding these guidelines would likely be required to induce sufficient skeletal muscle stimulation for a myokine response. Consequently, additional preclinical and clinical studies need to be Nature reviews | Urology undertaken to identify the different roles of myokines, depending on the characteristics of cancer cells, to provide myokine-targeted exercise prescriptions for patients with prostate cancer. ...
Article
Exercise is recognized by clinicians in the field of clinical oncology for its potential role in reducing the risk of certain cancers and in reducing the risk of disease recurrence and progression; yet, the underlying mechanisms behind this reduction in risk are not fully understood. Studies applying post-exercise blood serum directly to various types of cancer cell lines provide insight that exercise might have a role in inhibiting cancer growth via altered soluble and cell-free blood contents. Myokines, which are cytokines produced by muscle and secreted into the bloodstream, might offer multiple benefits to cellular metabolism (such as a reduction in insulin resistance, improved glucose uptake and reduced adiposity), and blood myokine levels can be altered with exercise. Alterations in the levels of myokines such as IL-6, IL-15, IL-10, irisin, secreted protein acidic risk in cysteine (SPARC), myostatin, oncostatin M and decorin might exert a direct inhibitory effect on cancer growth via inhibiting proliferation, promoting apoptosis, inducing cell-cycle arrest and inhibiting the epithermal transition to mesenchymal cells. The association of insulin resistance, hyperinsulinaemia and hyperlipidaemia with obesity can create a tumour-favourable environment; exercise-induced myokines can manipulate this environment by regulating adipose tissue and adipocytes. Exercise-induced myokines also have a critical role in increasing cytotoxicity and the infiltration of immune cells into the tumour.
... [4][5][6][7][8][9] At a cellular level, metabolites, hormonal differences, cell-to-cell signaling, cellular swelling, and intracellular signaling pathways have all been implicated. 5,6,[10][11][12][13] Metabolites, which accumulate during exercise and are known mediators of muscular hypertrophy, are amplified by BFR's relative ischemic and hypoxic conditions. They are believed to induce earlier, peripherally mediated fatigue, resulting in greater motor unit recruitment, as suggested by the fact that BFR under low loads has similar recruitment to that of high load resistance training. ...
... Stimulation of protein translation via the mechanistic target of rapamycin pathway, which is important in muscle protein synthesis and hypertrophy, 26-28 appears to play a fundamental role in the effects of BFR, 11,12 whereas myostatin, a negative regulator of muscle growth and promoter of muscle fibrosis, has been shown to be downregulated after BFR. 13,29,30 Although the exact contribution of each mechanistic pathway may not yet be completely understood, the available evidence offers important insight which will help guide further research to optimize rehabilitation efforts. ...
Article
Full-text available
Blood flow restriction (BFR) is an expanding rehabilitation modality that uses a tourniquet to reduce arterial inflow and occlude venous outflow in the setting of resistance training or exercise. Initially, this technique was seen as a way to stimulate muscular development, but improved understanding of its physiologic benefits and mechanism of action has allowed for innovative clinical applications. BFR represents a way to decrease stress placed on the joints without compromising improvements in strength, whereas for postoperative, injured, or load-compromised individuals BFR represents a way to accelerate recovery and prevent atrophy. There is also growing evidence to suggest that it augments cardiovascular fitness and attenuates pain. The purpose of this review is to highlight the physiology and evidence behind the various applications of BFR, with a focus on postoperative rehabilitation. While much remains to be learned, it is clear that blood flow restriction therapy stimulates muscle hypertrophy via a synergistic response to metabolic stress and mechanical tension, with supplemental benefits on cardiovascular fitness and pain. New forms of BFR and expanding applications in postoperative patients and athletes hold promise for expedited recovery. Continued adherence to rehabilitation guidelines and exploration of BFRs physiology and various applications will help optimize its effect and prescription. Level of Evidence V, expert opinion.
... (5,6) Unlike several types of RE that used high intensity (70% -85%), blood flow restriction (BFR) training with low load (20-50% 1RM or MVC), called Kaatsu training, stands out. (7) This training method showed positive results, as increased muscle strength and mass, similar to high-load training (HLT), so much in adults, (8,9) elderly, (10)(11)(12) and athletes. (13,14) One of RE's effects due to intensity use and repetitive of musculature is muscle fatigue, being responsible for a progressive decline in performance. ...
... Metabolic stress is currently known as a physiological process that occurs during exercise in response to low energy that leads to metabolite accumulation [lactate, phosphate inorganic (Pi), and ions of hydrogen (H+)] in muscle cells. (9,20) The metabolic stress can produce Oxigen-reactive species (ROS), which at moderate antioxidant capacity and immune response (21) . ...
Article
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Background: Photobiomodulationtherapy with static magnetic field (PBMT/sMF) stands out for being a non-pharmacological resource with bioenergetic effects capable of accelerating muscle recovery, delaying muscle fatigue and potentiate gains in different training protocols. In recent years, blood flow restriction (BFR) associated with low load exercise (20-30% 1RM/MVC) has demonstrated positive effects on muscle performance. However, the effects of PBMT/sMF combined with BFR training are still unknown. Objective:Verify the effects of PBMT/sMF associated with BFR training and compared with high load training (HLT) in the muscle strength, muscle damage, inflammation, and the oxidative stress. Methods:This are a protocol of a randomized, double-blind, placebo-controlled clinical trial. Theparticipants will be healthy men between the ages of 18 to 40 years, with no practice in upper limb strength training in the previous three months. The voluntaries will be randomly divided into four groups: (1) PBMT/sMF + BFR;(2) PBMT/sMF + HLT; (3) placebo + BFR; (4) placebo + HLT. The PBMT/sMF will be applied immediately before strengthening protocol (4 sets x 20 repetitions of elbow flexion). The BFR groups will undergo to exercise with low load (30% of MVC), while the HLT groups will performed the same protocol with 80 % of MVC. The primary outcome will be muscle strength, measured in baseline, fourth, eighth week of training and detraining period. The secondary outcomes include measured the fatigue resistance, arm circumference, muscle damage, inflammatory and oxidative stress levels in one session, during, after intervention and detraining. Discuss:This trial will elucidate the effects of PBMT/sMF when when used in association with BFR training or HLT.Keywords:Phototherapy; Muscle performance; Occlusion vascular; Oxidative stress; Exercise
... Low intensity resistance exercise combined with blood flow restriction (BFR) has been shown to improve muscle strength and mass (Abe et al., 2005;Laurentino et al., 2012;Bjørnsen et al., 2019); however, a meta-analysis by Lixandrão et al. (2018) suggests that BFR training stimulates similar gains in muscle hypertrophy but smaller increases in strength compared to traditional high intensity resistance training intensity (≥65% 1 repetition maximum, 1RM). This type of training program may be beneficial for individuals who have difficulty performing high intensity resistance exercise, such as those with chronic diseases such as multiple sclerosis, osteoporosis, and osteoarthritis (Freitas et al., 2021). ...
... Wilson et al. (2013) reported that muscle activation increased by ~20 mV and swelling increased 0.5 cm, while muscle damage indices remained unchanged during acute bouts of practical BFR. It is welldocumented that low intensity BFR resistance exercise increases muscle protein synthesis by altering signaling pathways, including the mammalian target of rapamycin complex 1 (mTORC1) and the inhibition of atrogenes like Muscle RING Finger1 (MuRF1) and atrogin-1 and the inhibition of the myostatin pathway (Fujita et al., 2007;Fry et al., 2010;Laurentino et al., 2012). ...
Article
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In this study, we compared acute and chronic bone marker and hormone responses to 6 weeks of low intensity (20% 1RM) blood flow restriction (BFR20) resistance training to high intensity (70% 1RM) traditional resistance training (TR70) and moderate intensity (45% 1RM) traditional resistance training (TR45) in young men (18–35 years). Participants were randomized to one of the training groups or to a control group (CON). The following training programs were performed 3 days per week for 6 weeks for knee extension and knee flexion exercises: BFR20, 20%1RM, 4 sets (30, 15, 15, 15 reps) wearing blood flow restriction cuffs around the proximal thighs; TR70, 70% 1RM 3 sets 10 reps; and TR45, 45% 1RM 3 sets 15 reps. Muscle strength and thigh cross-sectional area were assessed at baseline, between week 3 and 6 of training. Acute bone marker (Bone ALP, CTX-I) and hormone (testosterone, IGF-1, IGFBP-3, cortisol) responses were assessed at weeks 1 and 6, with blood collection done in the morning after an overnight fast. The main findings were that the acute bone formation marker (Bone ALP) showed significant changes for TR70 and BFR20 but there was no difference between weeks 1 and 6. TR70 had acute increases in testosterone, IGF-1, and IGFBP-3 (weeks 1 and 6). BFR20 had significant acute increases in testosterone (weeks 1 and 6) and in IGF-1 at week 6, while TR45 had significant acute increases in testosterone (week 1), IGF-1 (week 6), and IGFBP-3 (week 6). Strength and muscle size gains were similar for the training groups. In conclusion, low intensity BFR resistance training was effective for stimulating acute bone formation marker and hormone responses, although TR70 showed the more consistent hormone responses than the other training groups.
... There were statistically significant differences at the level of significance (α=< 0.05) in the perceptions of the members of the study sample on the extent of the use of educational technology and the life-based learning approach in handball courses from the point of view of the students of the Faculty of Physical Education depending on the variable university rate attributed to pass level. Karabulut et al., 2010 ;Clark et al., 2011;Laurentino et al., 2012;Libardi et al., 2015;Vechin et al.,2015;Thiebaud et al., 2013;alhamad,2017 Loenneke et al., 2012b;Yamanaka et al., 2012;Luebbers et al., 2014;Nishimura et al., 2010;Cook et al., 2007;Yasuda et al., 2011;Sumide et al., 2009 . Abe et al., 2010 ;Fujita et al., 2008 ;;Madarme et al., 2008;Laurentino et al., 2012 ;Takarada et al., 2002;Laurentino et al., 2008 ( ‫ﻛﻤﺎ‬ ‫اﻟﻌﺎﻣﻠﺔ‬ ‫ﻟﻠﻌﻀﻼت‬ ‫اﻟﺨﺎص‬ ‫اﻟﺘﺤﻤﻞ‬ ‫ﻟﺼﺎﻟﺢ‬ ‫واﺿﺤﺔ‬ ‫ﻧﺘﺎﺋﺞ‬ ‫اﻟﻰ‬ ‫أﺧﺮى‬ ‫دراﺳﺎت‬ ‫أﺷﺎرت‬ ) Kacin & strazer, 2011 ) ( (Loenneke et al., 2012b) . ...
... Karabulut et al., 2010 ;Clark et al., 2011;Laurentino et al., 2012;Libardi et al., 2015;Vechin et al.,2015;Thiebaud et al., 2013;alhamad,2017 Loenneke et al., 2012b;Yamanaka et al., 2012;Luebbers et al., 2014;Nishimura et al., 2010;Cook et al., 2007;Yasuda et al., 2011;Sumide et al., 2009 . Abe et al., 2010 ;Fujita et al., 2008 ;;Madarme et al., 2008;Laurentino et al., 2012 ;Takarada et al., 2002;Laurentino et al., 2008 ( ‫ﻛﻤﺎ‬ ‫اﻟﻌﺎﻣﻠﺔ‬ ‫ﻟﻠﻌﻀﻼت‬ ‫اﻟﺨﺎص‬ ‫اﻟﺘﺤﻤﻞ‬ ‫ﻟﺼﺎﻟﺢ‬ ‫واﺿﺤﺔ‬ ‫ﻧﺘﺎﺋﺞ‬ ‫اﻟﻰ‬ ‫أﺧﺮى‬ ‫دراﺳﺎت‬ ‫أﺷﺎرت‬ ) Kacin & strazer, 2011 ) ( (Loenneke et al., 2012b) . ‫واﺷﺎر‬ ) Fujita et al., 2007;Cook et al., 2007 ( ‫ان‬ ‫اﻟﻰ‬ (GH) Takenaka, K., Hirata, Y., Eto, F., Nagai, R., Sato, Y. and Nakaajima, T. (2005)." ...
Research Proposal
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الكتابة التاريخية عن الاتراك العثمانيين 1500-1900م قراءة في المصادر الاولية
... Blood flow restriction (BFR) is a commonly used technique by physical therapists and trainers aiming at physical rehabilitation and neuromuscular adaptations (Nakajima et al., 2006;Patterson and Brandner, 2018;de Queiros et al., 2021). This is certainly justified by the fact that some evidence indicates that lowload {20-40% of 1 repetition maximum [1RM] (Lopez et al., 2021)} resistance training with arterial BFR and venous occlusion artificially induced can promote gains in muscle strength and hypertrophy more pronounced than low-load resistance training without BFR (NO-BFR) (Loenneke et al., 2012) and, in some cases, similar to NO-BFR high-load resistance training (Takarada et al., 2000a;Laurentino et al., 2012). Due to structural and functional adaptations independent of high mechanical stress, BFR resistance training has been recommended for clinical populations with articular limitations for high-load resistance training (Vanwye et al., 2017). ...
... Although the aforementioned theory finds support to some extent, one needs to consider that in the study by Laurentino et al. (2012), a low-load resistance training program combined with BFR promoted hypertrophy similar to a high-load resistance training program (80% of 1RM). Our analyses indicated that the NO-BFR high-load exercise promoted higher myoelectric activity than the low-load exercise with BFR, regardless of the level of restriction (40% or 80% AOP). ...
Article
Full-text available
Background: Low-load resistance exercise (LL-RE) with blood flow restriction (BFR) promotes increased metabolic response and fatigue, as well as more pronounced myoelectric activity than traditional LL-RE. Some studies have shown that the relative pressure applied during exercise may have an effect on these variables, but existing evidence is contradictory. Purpose: The aim of this study was to systematically review and pool the available evidence on the differences in neuromuscular and metabolic responses at LL-RE with different pressure of BFR. Methods: The systematic review and meta-analysis was reported according to PRISMA items. Searches were performed in the following databases: CINAHL, PubMed, Scopus, SPORTDiscus and Web of Science, until June 15, 2021. Randomized or nonrandomized experimental studies that analyzed LL-RE, associated with at least two relative BFR pressures [arterial occlusion pressure (AOP)%], on myoelectric activity, fatigue, or metabolic responses were included. Random-effects meta-analyses were performed for MVC torque (fatigue measure) and myoelectric activity. The quality of evidence was assessed using the PEDro scale. Results: Ten studies were included, all of moderate to high methodological quality. For MVC torque, there were no differences in the comparisons between exercise with 40–50% vs. 80–90% AOP. When analyzing the meta-analysis data, the results indicated differences in comparisons in exercise with 15–20% 1 repetition maximum (1RM), with higher restriction pressure evoking greater MVC torque decline (4 interventions, 73 participants; MD = −5.05 Nm [95%CI = −8.09; −2.01], p = 0.001, I2 = 0%). For myoelectric activity, meta-analyses indicated a difference between exercise with 40% vs. 60% AOP (3 interventions, 38 participants; SMD = 0.47 [95%CI = 0.02; 0.93], p = 0.04, I2 = 0%), with higher pressure of restriction causing greater myoelectric activity. This result was not identified in the comparisons between 40% vs. 80% AOP. In analysis of studies that adopted pre-defined repetition schemes, differences were found (4 interventions, 52 participants; SMD = 0.58 [95%CI = 0.11; 1.05], p = 0.02, I2 = 27%). Conclusion: The BFR pressure applied during the LL-RE may affect the magnitude ofmuscle fatigue and excitability when loads between 15 and 20% of 1RM and predefined repetition protocols (not failure) are prescribed, respectively.
... These findings, combined with some observations of similar percentage changes in muscle strength and hypertrophy (Kubo et al., 2006;Martín-Hernández et al., 2013;Ozaki et al., 2013), suggest that hypertrophy may be a major factor contributing to BFRT-induced strength gains. In contrast, pronounced BFRT-induced strength adaptations may be incongruent with minor/no muscle hypertrophy (Laurentino et al., 2012;Lixandrão et al., 2015;Vechin et al., 2015;Cook et al., 2018). For example, BFRT and HLRT increased leg extension 1-RM strength similarly (23.5% average) when compared to an untrained control group (Cook et al., 2018), but meaningful muscle hypertrophy did not occur as the change in muscle volume (4.5%) was not different to an untrained control group. ...
... The failure of training interventions in this study to induce meaningful skeletal muscle hypertrophy despite significant strength improvement provides further evidence that BFRT, like HLRT, increases strength mostly via neurological mechanisms. This was somewhat expected as strength adaptations following BFRT can outweigh hypertrophy (Laurentino et al., 2012;Lixandrão et al., 2015). However, the exact neurological mechanisms by which skeletal muscle strength adaptations occur following BFRT remain unclear. ...
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Resistance-based blood flow restriction training (BFRT) improves skeletal muscle strength and size. Unlike heavy-load resistance training (HLRT), there is debate as to whether strength adaptations following BFRT interventions can be primarily attributed to concurrent muscle hypertrophy, as the magnitude of hypertrophy is often minor. The present study aimed to investigate the effect of 7 weeks of BFRT and HLRT on muscle strength and hypertrophy. The expression of protein growth markers from muscle biopsy samples was also measured. Male participants were allocated to moderately heavy-load training (HL; n = 9), low-load BFRT (LL + BFR; n = 8), or a control (CON; n = 9) group to control for the effect of time. HL and LL + BFR completed 21 training sessions (3 d.week ⁻¹ ) comprising bilateral knee extension and knee flexion exercises (HL = 70% one-repetition maximum (1-RM), LL + BFR = 20% 1-RM + blood flow restriction). Bilateral knee extension and flexion 1-RM strength were assessed, and leg muscle CSA was measured via peripheral quantitative computed tomography. Protein growth markers were measured in vastus lateralis biopsy samples taken pre- and post the first and last training sessions. Biopsy samples were also taken from CON at the same time intervals as HL and LL + BFR. Knee extension 1-RM strength increased in HL (19%) and LL + BFR (19%) but not CON (2%; p < 0.05). Knee flexion 1-RM strength increased similarly between all groups, as did muscle CSA (50% femur length; HL = 2.2%, LL + BFR = 3.0%, CON = 2.1%; TIME main effects). 4E-BP1 (Thr37/46) phosphorylation was lower in HL and LL + BFR immediately post-exercise compared with CON in both sessions ( p < 0.05). Expression of other growth markers was similar between groups ( p > 0.05). Overall, BFRT and HLRT improved muscle strength and size similarly, with comparable changes in intramuscular protein growth marker expression, both acutely and chronically, suggesting the activation of similar anabolic pathways. However, the low magnitude of muscle hypertrophy was not significantly different to the non-training control suggesting that strength adaptation following 7 weeks of BFRT is not driven by hypertrophy, but rather neurological adaptation.
... In the majority of studies, this hypoxic milieu is created by pressurized cuffs that are placed at the most proximal portion of the respective limb leading to reduced venous return (11,12). Previous findings from multiple trials revealed that the combination of LL resistance training (20%-40% one-repetition maximum (1RM)) with BFR facilitated substantial increases in muscle growth (13)(14)(15)(16) and muscle strength (17), which are typically seen after high-load (HL) training with 70%-85% 1RM (10,18). Interestingly, recent evidence suggests that LL-BFR training induces not only muscular but also tendinous adaptations. ...
Article
Introduction: Low-load resistance training with blood flow restriction (LL-BFR) has emerged as a viable alternative to conventional high-load (HL) resistance training regimens. Despite increasing evidence confirming comparable muscle adaptations between LL-BFR and HL resistance exercise, only very little is known about tendinous mechanical and morphological adaptations after LL-BFR. Therefore, the aim of the present study was to examine the effects of 14 wk of LL-BFR and HL training on patellar tendon adaptations. Methods: Twenty-nine recreationally active male participants were randomly allocated into the following two groups: LL-BFR resistance training (20%-35% one-repetition maximum (1RM)) or HL resistance training (70%-85% 1RM). Both groups trained three times per week for 14 wk. One week before and after the intervention, patellar tendon mechanical and morphological properties were assessed via ultrasound and magnetic resonance imaging. In addition, changes in muscle cross-sectional area were quantified by magnetic resonance imaging and muscle strength via dynamic 1RM measurements. Results: The findings demonstrated that both LL-BFR and HL training resulted in comparable changes in patellar tendon stiffness (LL-BFR: +25.2%, P = 0.003; HL: +22.5%, P = 0.024) without significant differences between groups. Similar increases in tendon cross-sectional area were observed in HL and LL-BFR. Muscle mass and strength also significantly increased in both groups but were not statistically different between HL (+38%) and LL-BFR (+34%), except for knee extension 1RM where higher changes were seen in LL-BFR. Conclusions: The present results support the notion that both HL and LL-BFR cause substantial changes in patellar tendon properties, and the magnitude of changes is not significantly different between conditions. Further studies that examine the physiological mechanisms underlying the altered tendon properties after LL-BFR training are needed.
... Theoretically, the mechanical pressure should be applied in such a way that the venous return of blood is fully occluded and arterial inflow into the muscle is reduced but maintained, which results in a pooling of blood and localized hypoxia distal to the cuff (42,45,54). Although the exact underlying mechanisms remain poorly understood, it is hypothesized that low-load resistance training with BFR leads to an increased accumulation of metabolites, which is theorized to induce anabolic processes by acting on other factors including increases in systematic hormones (75,110) (e.g., insulin-like growth factor 1 [IGF-1]) and reactive oxygen species (92), increased recruitment of fasttwitch muscle fibers (24), diminished expression of myostatin (53), and cell swelling (62). These factors can activate further complex signal cascades that lead to an increase in protein biosynthesis as well as increased proliferation and activity of satellite cells (42,90). ...
Article
Bielitzki, R, Behrendt, T, Behrens, M, and Schega, L. Current techniques used for practical blood flow restriction training: a systematic review. J Strength Cond Res XX(X): 000-000, 2021-The purpose of this article was to systematically review the available scientific evidence on current methods used for practical blood flow restriction (pBFR) training together with application characteristics as well as advantages and disadvantages of each technique. A literature search was conducted in different databases (PubMed, Web of Science, Scopus, and Cochrane Library) for the period from January 2000 to December 2020. Inclusion criteria for this review were (a) original research involving humans, (b) the use of elastic wraps or nonpneumatic cuffs, and (c) articles written in English. Of 26 studies included and reviewed, 15 were conducted using an acute intervention (11 in the lower body and 4 in the upper body), and 11 were performed with a chronic intervention (8 in the lower body, 1 in the upper body, and 2 in both the upper and the lower body). Three pBFR techniques could be identified: (a) based on the perceptual response (perceived pressure technique), (b) based on the overlap of the cuff (absolute and relative overlap technique), and (c) based on the cuffs' maximal tensile strength (maximal cuff elasticity technique). In conclusion, the perceived pressure technique is simple, valid for the first application, and can be used independently of the cuffs' material properties, but is less reliable within a person over time. The absolute and relative overlap technique as well as the maximal cuff elasticity technique might be applied more reliably due to markings, but require a cuff with constant material properties over time.
... Blood occlusion through asphyxia during exercise likely contributes to hypertrophy [15]. It is possible that blood occlusion inhibits myostatin [16], which is known to play a role in cachexia. Although pyramidal training is suspected of impacting microvascular oxygenation during exercise, recent findings suggest that microvascular oxygenation is similar in pyramidal and traditional training [17]. ...
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Pyramidal systems refer to a particular type of resistance training in which sets are performed with increasing (or decreasing) weight, in such a way that the number of repetitions is low when the weight is high (and vice versa). Multiple implementations exist such as the light-to-heavy, triangle or asymmetric triangle system. They are similar to traditional training, but with slightly different impact on training volume, endurance or power outcome. Therefore, pyramidal systems are ideal candidates for practitioners willing to tune their training routine.
... In fact, follistatin-induced inhibition of SMAD3 activity, which leads to induction of protein synthesis in skeletal muscles via Akt/mTORC1/S6K signaling, occurs also through inhibition of activin, another follistatin-and ActRIIB-ligand implicated in both muscle mass and strength loss in various conditions (Gilson et al., 2009;Winbanks et al., 2012). Although there are not many human training studies available, both serum follistatin as well as skeletal muscle follistatin mRNA levels seem to be upregulated upon long-term resistance training (Laurentino et al., 2012;Negaresh et al., 2019). The observation that follistatin is not only elevated in muscle, but also in the circulation, leads to the question whether muscle-derived follistatin-besides controlling skeletal muscle adaptation in a local manner-also operates systemically. ...
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Exercise, in the form of endurance or resistance training, leads to specific molecular and cellular adaptions not only in skeletal muscles, but also in many other organs such as the brain, liver, fat or bone. In addition to direct effects of exercise on these organs, the production and release of a plethora of different signaling molecules from skeletal muscle are a centerpiece of systemic plasticity. Most studies have so far focused on the regulation and function of such myokines in acute exercise bouts. In contrast, the secretome of long-term training adaptation remains less well understood, and the contribution of non-myokine factors, including metabolites, enzymes, microRNAs or mitochondrial DNA transported in extracellular vesicles or by other means, is underappreciated. In this review, we therefore provide an overview on the current knowledge of endurance and resistance exercise-induced factors of the skeletal muscle secretome that mediate muscular and systemic adaptations to long-term training. Targeting these factors and leveraging their functions could not only have broad implications for athletic performance, but also for the prevention and therapy in diseased and elderly populations.
... The mechanical tension generated by the cuff increases metabolic stress and is the main physiological mechanism influencing muscle adaptation after resistance training under BFR. The increase of metabolic stress during resistance exercise under BFR results in cell swelling [24], enhances intramuscular signaling [19,28], increases recruitment of fast-twitch muscle fibers [27,40] and enhances responses of the June 2021 GAWEL, JAROSZ, MATYKIEWICZ, KASZUBA, TRYBULSKI endocrine system [36,39]. Furthermore, the hyperemia following occlusion may play a significant role in nitric oxide production [37], increased phosphocreatine resynthesis, altered oxy-deoxyhemoglobin kinetics [3] and increased oxygen uptake [1]. ...
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Introduction. Athletes, as well as recreationally trained individuals are increasingly looking for innovative techniques and methods of resistance training to provide an additional stimulus to break through plateaus, prevent monotony and achieve various training goals. Partial or total blood flow restriction (BFR) to the working muscles during resistance exercise has been used as a complementary training modality, aiming to further increase muscle mass and improve strength. BFR is usually used during low-load resistance exercise and has been shown to be effective in enhancing long-term hypertrophic and strength responses in both clinical and athletic populations. However, recently some attention has been focused on the acute effects of BFR on strength and power performance during highload resistance exercise. Aim of Study. This article provides an overview of available scientific literature and describes how BFR affects the 1-repetition maximum (1RM), the number of repetitions performed, time under tension and kinematic variables such as power output and bar velocity. Material and Methods. Available scientific literature. Results. As a result, BFR could be an important tool in eliciting greater maximal load, power output and strength-endurance performance during resistance exercise. Conclusions. BFR as a training tool can be used as an additional factor to help athletes and coaches in programming varied resistance training protocols.
... Blood flow restricted exercise involves completing low load/intensity exercise with pneumatic/elastic cuffs applied to active limbs Patterson et al., 2019). This form of exercise has conferred chronic muscular (Farup et al., 2015;Kim et al., 2017;Laurentino et al., 2012) and cardiovascular adaptations (Mouser et al., 2019) across a wide range of populations. Due to its beneficial physiological adaptations over that of volume-matched low load/intensity exercise by itself (Abe et al., 2006;Shinohara et al., 1998), blood flow restricted exercise may offer a more appealing method of exercise for those who cannot or are not willing to lift heavy loads or exercise at higher intensities . ...
Article
The purpose of this study was to investigate whether isometric handgrip exercise, with or without blood flow restriction, would alter interference control and feelings. 60 healthy young adults completed three experimental visits, consisting of four sets of two‐minutes isometric handgrip exercise, at 30% of maximal strength with or without blood flow restriction (50% of arterial occlusion pressure), or a non‐exercise/time‐matched control. Exercise‐induced feeling inventory and Stroop Color Word Test were performed at pre‐ and ~10‐minute post‐exercise, respectively. Bayes factors (BF10) quantified the evidence for or against the null. There were no changes or differences between conditions for interference control following exercise with or without blood flow restriction (Incongruent BF10: 0.155; Stroop Interference BF10: 0.082). There were also no differences in the error rate as well as no differences between conditions for changes in “positivity” or “revitalization”. Feelings of “tranquility” were reduced relative to a control following exercise with [median δ (95% credible interval): ‐0.74 (‐1.05, ‐0.45), BF10: 5515.7] and without [median δ: ‐0.72 (‐1.02, ‐0.41), BF10: 571.3] blood flow restriction. These changes were not different between exercise conditions. Feelings of “physical exhaustion” were increased relative to a control following exercise without blood flow restriction [median δ: 0.35(0.09, 0.61), BF10: 5.84]. However, this increase was not different from the same exercise with blood flow restriction. These results suggest that 1) isometric handgrip exercise could be performed without impairing interference control, even when blood flow restriction is added, and that 2) changes in feelings occur independent of changes in interference control.
... Fstl3 is expressed and secreted in skeletal muscle. An overexpression of Fstl3 in mice fed with high-fat diet leads to fat gain and an improvement in insulin signaling (43)(44)(45). DLK1 (also called preadipocyte factor one) also plays a role in adipose tissue homeostasis Values represent means ± SD *p < 0.05, **p < 0.01 (t-test, Mann-Whitney test). Differences in biochemical and physiological parameters in serum, pancreas and vAT between the two subgroups. ...
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Recent studies have shown an association between iron homeostasis, obesity and diabetes. In this work, we investigated the differences in the metabolic status and inflammation in liver, pancreas and visceral adipose tissue of leptin receptor-deficient db/db mice dependent on high iron concentration diet. 3-month-old male BKS-Leprdb/db/JOrlRj (db/db) mice were divided into two groups, which were fed with different diets containing high iron (29 g/kg, n = 57) or standard iron (0.178 g/kg; n = 42) concentrations for 4 months. As anticipated, standard iron-fed db/db mice developed obesity and diabetes. However, high iron-fed mice exhibited a wide heterogeneity. By dividing into two subgroups at the diabetes level, non-diabetic subgroup 1 (<13.5 mmol/l, n = 30) significantly differed from diabetic subgroup two (>13.5 mmol/l, n = 27). Blood glucose concentration, HbA1c value, inflammation markers interleukin six and tumor necrosis factor α and heme oxygenase one in visceral adipose tissue were reduced in subgroup one compared to subgroup two. In contrast, body weight, C-peptide, serum insulin and serum iron concentrations, pancreatic islet and signal ratio as well as cholesterol, LDL and HDL levels were enhanced in subgroup one. While these significant differences require further studies and explanation, our results might also explain the often-contradictory results of the metabolic studies with db/db mice.
... Isometric exercise in combination with blood flow restriction has been reported to induce greater metabolic stress and fatigue compared to when isometric exercise is performed without blood flow restriction (Cayot et al., 2016;Copithorne & Rice, 2019;Ilett et al., 2019). It has been established that low load resistance training, in combination with blood flow restriction, can enhance muscle size similar to that of traditional high load resistance training Laurentino et al., 2012;Ozaki et al., 2013). Increases in muscle strength are also observed following low load resistance training with blood flow restriction, but often to a smaller magnitude to that of high load resistance training (Kim et al., 2017;Martín-Hernández et al., 2013;Yasuda et al., 2011). ...
Article
The purpose was to examine the effect of isometric handgrip exercise with and without blood flow restriction on exercise-induced hypoalgesia at a local and non-local site, and its underlying mechanisms. Sixty participants (21 males & 39 females, 18–35 years old) completed 3 trials: four sets of 2-minute isometric handgrip exercise at 30% of maximum handgrip strength; isometric handgrip exercise with blood flow restriction at 50% of arterial occlusion pressure; and a non-exercise time-matched control. Pain thresholds increased similarly in both exercise conditions at a local (exercise conditions: ~0.45 kg/cm², control: ~-0.04 kg/cm²) and non-local site (exercise conditions: ~0.37 kg/cm², control: ~-0.16 kg/cm²). Blood flow restriction induced greater feelings of discomfort compared to exercise alone [median difference (95% credible interval) of 4.5 (0.5, 8.6) arbitrary units]. Blood pressure increased immediately after exercise (systolic: 10.3 mmHg, diastolic: 7.7 mmHg) and decreased in recovery. There was no within participant correlation between changes in discomfort and pressure pain threshold. A bout of isometric handgrip exercise with or without blood flow restriction can provide exercise-induced hypoalgesia at a local and non-local site. However, discomfort and changes in systolic blood pressure do not explain this response.
... It is well-established that LL combined with BFR (LL-BFR) promotes similar increases in muscle cross-sectional area (CSA) [8][9][10][11] and lower psychophysiological stress (ie, rating of perceived exertion [RPE] and pain) 12 when compared with traditional resistance training protocols (ie, with high load), despite the lower volume load (sets × repetitions × load [in kilograms]). In contrast, little is known about the effects of NES combined with BFR (NES-BFR), which has been recommended during the initial stages of rehabilitation. ...
Article
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Context: Low-load resistance training (LL) and neuromuscular electrostimulation (NES), both combined with blood flow restriction (BFR), emerge as effective strategies to maintain or increase muscle mass. It is well established that LL-BFR promotes similar increases in muscle cross-sectional area (CSA) and lower rating of perceived exertion (RPE) and pain compared with traditional resistance training protocols. On the other hand, only 2 studies with conflicting results have investigated the effects of NES-BFR on CSA, RPE, and pain. In addition, no study directly compared LL-BFR and NES-BFR. Objective: The aim of the study was to compare the effects of LL-BFR and NES-BFR on vastus lateralis CSA, RPE, and pain. Individual response for muscle hypertrophy was also compared between protocols. Design: Intrasubject longitudinal study. Setting: University research laboratory. Intervention: Fifteen healthy young males (age = 23 [5] y; weight = 77.6 [11.3] kg; height = 1.76 [0.08] m). Main outcome measures: Vastus lateralis CSA was measured through ultrasound at baseline (pre) and after 20 training sessions (post). The RPE and pain responses were obtained through modified 10-point scales, handled during all training sessions. Results: Both protocols demonstrated significant increases in muscle CSA (P < .0001). However, the LL-BFR demonstrated significantly greater CSA changes compared with NES-BFR (LL-BFR = 11.2%, NES-BFR = 4.6%; P < .0001). Comparing individual increases in CSA, 12 subjects (85.7% of the sample) presented greater muscle hypertrophy for LL-BFR than for the NES-BFR protocol. In addition, LL-BFR produced significantly lower RPE and pain responses (P < .0001). Conclusions: The LL-BFR produced significantly greater increases in CSA with significant less RPE and pain than NES-BFR. In addition, LL-BFR resulted in greater individual muscle hypertrophy responses for most subjects compared with NES-BFR.
... 1,3 Prior studies have shown that BFR applied during low-intensity resistance training can produce significant muscle hypertrophy and strength gains similar to that of traditional highintensity resistance training but using loads as low as 30% of the 1 repetition maximum. 4,5 Resistance training supplemented with BFR has also been shown to elicit joint improvements in both strength and endurance capacity. [6][7][8] Recent studies have focused more on the combination of BFR and aerobic exercise as an adapted training method for either maintaining or improving aerobic performance in physically active individuals at a lower training intensity. ...
Article
Purpose: To determine if, in physically active individuals, low-intensity Blood Flow Restriction (BFR) training is more effective than training without BFR at improving measures of aerobic capacity. Methods: A database search was conducted for articles that matched inclusion criteria (minimum level 2 evidence, physically active participants, comparison of low-intensity BFR to no BFR training, comparison of pre-post testing with aerobic fitness or performance, training protocols >2 weeks, studies published after 2010) by two authors and assessed by one using the PEDro scale (a minimum of 5/10 was required) to ensure level 2 quality studies that were then analyzed. Results: Four studies met all inclusion criteria. Three of the studies found significant improvements in aerobic capacity (VO2max) using BFR compared to no BFR. While the fourth study reported significant improvements in time to exertion (TTE) training with BFR, this same study did not find significant improvements in measures of aerobic capacity with BFR training. All compared BFR to non-BFR training. It was noted that high-intensity training without BFR was superior to both low-intensity training with and without BFR with respect to improvements in aerobic capacity. Conclusions: Moderate evidence exists to support the use of low-intensity BFR training to improve measures of aerobic capacity in physically active individuals over not using BRF. Clinicians seeking to maintain aerobic capacity in their patients who are unable, for various reasons, to perform high levels of aerobic activity may find low-intensity BFR training useful as a substitution while still receiving improvements in measures of aerobic capacity.
... The results of the present study indicate LL + BFR and LL resistance training was not associated with DOMS. These findings, in conjunction with previous investigations [25][26][27] that examined the ability of LL + BFR and LL to elicit increases in muscle strength and size, suggest that LL + BFR and LL training may be particularly useful among various populations including older adults, those undergoing rehabilitation, and athletes. Specifically, LL + BFR and LL may allow for early post-surgical exercise conditioning [28][29][30], increased exercise program adherence [31,32], and allow athletes to achieve positive muscular adaptations without experiencing the adverse effects of DOMS on sports performance [33]. ...
Article
BACKGROUND: Low-load resistance training with blood flow restriction (LL + BFR) attenuated delayed onset muscle soreness (DOMS) under some conditions. OBJECTIVE: The purpose of this study examined the effects of reciprocal concentric-only elbow flexion-extension muscle actions at 30% of peak torque on indices of DOMS. METHODS: Thirty untrained women (mean ± SD; 22 ± 2.4 years) were randomly assigned to 6 training days of LL + BFR (n= 10), low-load non-BFR (LL) (n= 10), or control (n= 10). Participants completed 4 sets (1 × 30, 3 × 15) of submaximal (30% of peak torque), unilateral, isokinetic (120∘s-1) muscle actions. Indices of DOMS including peak power, resting elbow joint angle (ROM), perceived muscle soreness (VAS), and pain pressure threshold (PPT) were assessed. RESULTS: There were no changes in peak power, ROM, or VAS. There was a significant interaction for PPT. Follow-up analyses indicated PPT increased for the LL + BFR condition (Day 5 > Day 2), but did not decrease below baseline. The results of the present study indicated LL + BFR and LL did not induce DOMS for the elbow extensors in previously untrained women. CONCLUSION: These findings suggested LL + BFR and LL concentric-only resistance training could be an effective training modality to elicit muscular adaptation without inducing DOMS.
... In this regard, it has been proven that BFRT leads to increase in muscle mass greater than without BFRT (7). Evidence suggests that BFRT may modulate some myokines (9). Follistatin (FST) is a glycosylated protein that is a member of the transforming growth factorbeta (TGF-β) family and contributes to the development of muscle mass (10). ...
Article
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Background and objectives: Blood flow restriction training (BFRT) has gained substantial interest due to the lower required intensity, which may be beneficial for individuals who are not able to lift heavy weights. Therefore, we aimed at evaluating effects of 12 weeks of resistance training with and without blood flow restriction on follistatin (FST) concentrations and physical performance in elderly females. Methods: Thirty elderly female were randomly assigned into the following groups: resistance training with blood flow restriction (BFRT; n=10), resistance training without blood flow restriction (WBFRT; n=10) and control ( n=10). The resistance training was carried out three session a week for 12 weeks. Serum concentrations of FST, muscular endurance and dynamic balance were assessed at baseline and after the 12week intervention. Results: Significant main effects of time were observed for FST (p =0.03, η2 = 0.15), muscular endurance (p = 0.00, η2 = 0.59) and dynamic balance (p=0.00, η2 = 0.57). FST [BFRT= 1.4 ng/ml (effect size Cohen’s {d} = -0.8) significantly increased only in BFRT group. However, muscular endurance [BFRT= 95 (d= -4.1) and WBFRT = 32 (d= -0.9)] significantly increased in both intervention groups (P
... During resistance exercise such as weight training, follistatin mRNA expression increases in skeletal muscle tissue biopsies from women on hormone replacement therapy (100). The same observation was made in healthy young men after a session of strength training (101). However, recently we have shown that follistatin is also secreted by the liver in response to exercise. ...
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The regulation of insulin secretion is under control of a complex inter-organ/cells crosstalk involving various metabolites and/or physical connections. In this review, we try to illustrate with current knowledge how β-cells communicate with other cell types and organs in physiological and pathological contexts. Moreover, this review will provide a better understanding of the microenvironment and of the context in which β-cells exist and how this can influence their survival and function. Recent studies showed that β-cell insulin secretion is regulated also by a direct and indirect inter-organ/inter-cellular communication involving various factors, illustrating the idea of “the hidden face of the iceberg”. Moreover, any disruption on the physiological communication between β-cells and other cells or organs can participate on diabetes onset. Therefore, for new anti-diabetic treatments’ development, it is necessary to consider the entire network of cells and organs involved in the regulation of β-cellular function and no longer just β-cell or pancreatic islet alone. In this context, we discuss here the intra-islet communication, the β-cell/skeletal muscle, β-cell/adipose tissue and β-cell/liver cross talk.
... 36 This occurrence combined with increased muscle fiber recruitment due to fatigue, structural strain from muscle cell swelling, and release of signaling effectors from muscle (eg, myokines, local insulin-like growth factors [IGFs], microRNA) has been hypothesized to directly and indirectly stimulate muscle anabolism via the aforementioned signaling pathways in concurrence with other mechanisms involved in the regulation of cell growth and degradation. 1,20,25,39,55,60 Because metabolic and mechanical stress is primarily experienced by muscles distal to the site of occlusion, one may speculate that proximal muscles (where blood flow is not occluded) may not experience the same stimulatory effects with regard to changes in strength and muscle mass. However, it has been postulated that BFR can provide benefits to muscle groups directly proximal to the site of occlusion via local paracrine or systemic action as well as elevated muscle fiber recruitment. ...
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Background: Although blood flow restriction (BFR) is becoming increasingly popular in physical therapy and athletic training settings, little is known about the effects of BFR combined with low-intensity exercise (LIX) on muscles proximal to the site of occlusion. Hypothesis/Purpose: Determine whether LIX combined with BFR applied distally to the shoulder on the brachial region of the arm (BFR-LIX) promotes greater increases in shoulder lean mass, rotator cuff strength, endurance, and acute increases in shoulder muscle activation compared with LIX alone. We hypothesized that BFR-LIX would elicit greater increases in rotator cuff strength, endurance, and muscle mass. We also hypothesized that the application of BFR would increase EMG amplitude in the shoulder muscles during acute exercise. Study Design: Controlled laboratory study. Methods: 32 healthy adults were randomized into 2 groups (BFR group, 13 men, 3 women; No-BFR group, 10 men, 6 women) who performed 8 weeks of shoulder LIX (2 times per week; 4 sets [30/15/15/fatigue]; 20% maximum) using common rotator cuff exercises (cable external rotation [ER], cable internal rotation [IR], dumbbell scaption, and side-lying dumbbell ER). The BFR group also trained with an automated tourniquet placed at the proximal arm (50% occlusion). Regional lean mass (dual-energy x-ray absorptiometry), isometric strength, and muscular endurance (repetitions to fatigue [RTF]; 20% maximum; with and without 50% occlusion) were measured before and after training. Electromyographic amplitude (EMGa) was recorded from target shoulder muscles during endurance testing. A mixed-model analysis of covariance (covaried on baseline measures) was used to detect within-group and between-group differences in primary outcome measures (α = .05). Results: The BFR group had greater increases in lean mass in the arm (mean ± 95% CI: BFR, 175 ± 54 g; No BFR, –17 ± 77 g; P < .01) and shoulder (mean ± 95% CI: BFR, 278 ± 90 g; No BFR, 96 ± 61 g; P < .01), isometric IR strength (mean ± 95% CI: BFR, 2.9 ± 1.3 kg; No BFR, 0.1 ± 1.3 kg; P < .01), single-set RTF volume (repetitions × resistance) for IR (~1.7- to 2.1-fold higher; P < .01), and weekly training volume (weeks 4, 6-8, ~5%-22%; P < .05). Acute occlusion (independent of group or timepoint) yielded increases in EMGa during RTF (~10%-20%; P < .05). Conclusion: Combined BFR-LIX may yield greater increases in shoulder and arm lean mass, strength, and muscular endurance compared with fatiguing LIX alone during rotator cuff exercises. These findings may be due, in part, to a greater activation of shoulder muscles while using BFR. Clinical Relevance: The present study demonstrates that BFR-LIX may be a suitable candidate for augmenting preventive training or rehabilitation outcomes for the shoulder. AJSM PODCAST DISCUSSION: http://sageorthopaedics.sage-publications.libsynpro.com/ajsm-august-2021-podcast-blood-flow-restriction-training-for-the-shoulder-a-case-for-proximal-benefit
... Although further researches are needed in order to make a precise recommendation for the use of optimal BFR stimuli, principal factors to consider are cuffs width and the circumference of the limb and if possible BFR should be individualized based on total arterial occlusion pressure. Preliminary results suggest that pressure equivalent to 50% to 80% of total arterial occlusion pressure could be optimal for muscular adaptation (Laurentino et al. 2012;Loenneke et al. 2014b;. ...
Thesis
La capacité à répéter des efforts de courte durée et d’intensité maximale est considérées comme un indicateur de la performance dans de nombreux sports intermittents (sports collectifs, sports d’opposition). Ce travail de thèse s’est focalisé sur l’étude de la fatigue neuromusculaire induite par une répétition de sprints et de l’impact que peut avoir l’hypoxie sur le développement de celle-ci. Il est établi qu’en condition normale l’origine de cette fatigue est d’avantage musculaire (périphérique) dès les premiers sprints alors qu’une fatigue dites centrale, correspondant à une incapacité du système nerveux centrale à recruter le muscle de manière optimale, apparait lors des derniers sprints. La réalisation de ce type d’effort en hypoxie a pour effet d’exacerber l’apparition de la fatigue, notamment centrale, de deux manières potentielles. Soit via une diminution de la quantité d’oxygène fournit au cerveau, ce qui aurait un effet direct diminuant l’activité cérébrale et donc la commande motrice nécessaire à l’exercice. Soit via la réduction de l’arrivée de l’oxygène au niveau musculaire, qui engendrerait une diminution de la part d’énergie produite par le métabolisme aérobie, qui serait redirigé vers le métabolisme anaérobie, connu pour produire davantage de déchets métaboliques. Ces derniers sont liés à des voies afférentes qui inhibe de manière indirect la commande motrice. L’un des objectifs était de pouvoir isoler ces deux mécanismes grâce à la mise en place d’une hypoxie musculaire localisée afin de voir si cela suffirait à induire une augmentation de la fatigue centrale. Les résultats présentés suggèrent que les deux types d’hypoxies diminuent la performance en sprint de manière similaire mais via des mécanismes distincts. L’hypoxie générale impact d’avantage le développement de la fatigue centrale via un effet direct sur le cerveau alors que l’hypoxie localisée augmente surtout la fatigue périphérique via l’accumulation de métabolites. Cependant la méthode utilisée dans cette étude et classiquement dans la littérature induit un délai entre la fin du sprint et la mesure de fatigue, ce qui peut induire une sous-estimation et une mauvaise interprétation de l’étiologie de celle-ci et ne permet pas d’établir une cinétique précise du développement de la fatigue. C’est pourquoi suite à cette première étude, l’objectif était de développer une méthode permettant des mesures régulières et sans délai de la fatigue neuromusculaire. Ce travail présente le développement et la validation d’un nouvel ergomètre permettant des mesures de la fonction neuromusculaire intégrées pendant un exercice de sprint répétés sur vélo.
... To promote safety, arterial pressure should be measured via Doppler ultrasound, which can be assessed via a handheld Doppler. This would allow for the LOP to be measured as a relative value in relation to individual arterial pressure and the use of a certain percentage of the arterial occlusion pressure (AOP) to ensure individual safety (13,20). Setting this AOP too high (.80% occlusion) can increase the risk of suffering an adverse event (e.g., subcutaneous hemorrhage or numbness), whereas too low (,40% occlusion) pressures may not guarantee an adequate stimulus to generate desired adaptations (5,30). ...
... O objetivo de restringir o influxo de sangue arterial ao membro é causar um estresse metabólico mais significativo e estimular os mecanismos de hipertrofia muscular, como recrutamento adicional de unidades motoras, edema celular, liberação de hormônios anabólicos, produção alterada de miocinas, e espécies reativas de oxigênio [9][10][11]. Embora a magnitude das respostas aos ganhos de força sejam menores do que as obtidas com as rotinas tradicionais de treinamento de força com altas cargas resistivas, o treinamento de contrarresistência com restrição de fluxo sanguíneo (RFS) pode ser uma estratégia mais adequada em populações que são incapazes de mobilizar alta sobrecarga, como os idosos [12], e pessoas em recuperação de lesão musculoesquelética ou de cirurgia [13]. ...
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RESUMO Introdução: O exercício contrarresistência com restrição do fluxo sanguíneo (RFS) é um método eficaz para ganho de força e hipertrofia muscular. No entanto, pouco se sabe sobre os efeitos dos diferentes níveis de RFS nas respostas hemodinâmicas. Objetivo: Verificar se as diferentes pressões de restrição ao fluxo sanguíneo aplicadas no membro superior causam alterações na microcirculação vascular em adul-tos jovens saudáveis do sexo masculino. Métodos: Dez jovens do sexo masculino visitaram o laboratório em quatro ocasiões. Na primeira visita, após 10 min de repouso em decúbito dorsal, a pressão de oclusão da artéria braquial (POA) foi identificada através de ultrassom com Doppler. Posteriormente, os parti-cipantes foram submetidos a um protocolo que consistia de 1 min para as medidas basais, 2 min de RFS e 2 min após a liberação da restrição sanguínea. Foi utilizado um manguito colocado na porção proxi-mal do antebraço e inflado com pressões equivalentes a 30% (30RFS), 50% (50RFS) 80% (80RFS) ou 100% (100RFS) do POA em ordem aleatória em dias separados. As medições do índice de saturação do tecido (IST), oxiemoglobina, desoxihemoglobina e hemoglobina total foram coletadas continuamente usando espectrometria de infravermelho próximo. Resultados: Uma ANOVA de duas vias com medidas repetidas demonstrou 1) uma diminuição significativa no IST em todas as condições, com maior queda em 100RFS; 2) um aumento significativo na oxihemoglobina em todas as condições, exceto 100RFS; 3) um aumento semelhante na desoxihemoglobina em todas as condições; 4) um aumento significativo na hemoglobina total em todas as condições, principalmente em 30RFS e 50RFS. Conclusão: As pressões relativas adotadas demonstraram que as alterações hemodinâmicas não ocorrem linearmente com o nível de pressão impos-to pelo manguito insuflado. Palavras-chave: espectroscopia de luz próxima ao infravermelho; dispositivos de oclusão vascular; treinamento de força. ABSTRACT Introduction: Resistance exercise with blood flow restriction (BFR) is an effective method to promote muscle strength gains and hypertrophy. However, little is known about the effects of different BFR levels on hemodynamic responses. Objective: To verify whether the different blood flow restriction pressures applied to the upper limb cause acute changes in vascular microcirculation in young, healthy male adults. Methods: Ten young male visited the laboratory on four occasions. In the first visit, after 10-min rest in supine position, the brachial artery occlusion pressure (AOP) was identified with a Doppler ultrasound. Thereafter, the participants were submitted to a protocol consisting of 1 min for baseline measurements, 2 min of BFR, and 2 min after cuff deflation. It was used a cuff placed on the proximal portion of the forearm and inflated with pressures equivalents to 30% (30BFR), 50% (50BFR) 80% (80BFR), or 100% (100BFR) of the AOP in a random order in separate days. Measurements of tissue saturation index (TSI), oxyhemoglobin, deoxyhemoglobin, and total hemoglobin were collected continuously using near-infrared spectrometry. Results: A two-way ANOVA with repeated measures demonstrated: 1) a significant decrease in TSI in all conditions, with higher decay in 100BFR; 2) a significant increase in oxyhemoglobin in all conditions, but 100BFR; 3) a similar increase in deoxyhemoglobin in all conditions; 4) a significant increase in total hemoglobin in all conditions, mainly in both 30BFR and 50BFR. Conclusion: The relative pressures adopted demonstrated that the hemodynamic changes do not occur linearly with the pressure level imposed by the inflated cuff.
... (7,9) Bu nedenle, iskemik ön koşullandırmanın oksidatif sistem tarafından tamamen kullanıldığında, çeşitli egzersiz modlarında maksimum performansı artırdığı bildirilmiştir. (10,11,12) Bu bağlamda, artan metabolik stres (13) artmış kas katılımı (14) kas içi protein sentezi üzerindeki etki (15,16) miyojenik kök hücrelerin proliferasyonuna (17) kadar çeşitli mekanizmalar tartışılmıştır. ...
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Kalp-damar sistemi, doku veya organların işlevlerini kontrol edilebilmek için gerekli olan kan ihtiyacını karşılaması gerekmektedir. Bu ihtiyacın karşılanması sırasında yaşanacak olan denge ve kesinti sorunları ilgili doku ya da organdaki işlev bozukluğuna yol açarak iskemi durumunu ortaya çıkarmaktadır. Bu durumda yaşanan oklüzyon-reperfüzyon durumu (kan akımı kısıtlama ve tekrar serbestleme / yetersizlik-kanlanma) bazı doku-organ hasarlarına sebebiyet verebilmektedir. Aynı zamanda, yaşanan bu evrede bazı metabolit oluşumları nedeniyle farklı dokularda da negatif yönde etkilenmeler ortaya çıkabilmektedir. (1) İskemik ön koşullandırma (kalp kası üzerinde) ilk olarak 1986 yılında uygulanmıştır. (2) Kalp kasında (miyokard), kalbi besleyen damarların (koroner) oklüzyonu (40 dakikalık) öncesi, reperfüzyon aralıkları (5’ er dakikalık) düzenlenerek ilgili damarların tıkanması sonucunda hücrelerdeki ölüm (nekroz) oranı (yaklaşık %75) oldukça azalmıştır. (3,4) İskemik ön koşullandırmada deneyi; hayvanlarda (köpek) yapılan, ölümcül olmayan, kardiyak iskemi-reperfüzyon aralıklarının daha sonra uzun süreli kardiyak iskemiye karşı koruma sağladığını gösteren bir deneydir. Kısa aralıklı oklüzyon-reperfüzyon döngülerine ve ardından hiperemiye maruz kalmadan oluşan iskemik ön koşullandırmanın (iskemik preconditioning / IPC) dokuları iskemiye karşı koruduğu kanıtlanmıştır. (2)
Article
This study systematically reviewed the available scientific evidence on the changes promoted by low-intensity (LI) resistance training (RT) combined with blood flow restriction (BFR) on blood pressure (BP), heart rate (HR) and rate-pressure product (RPP). Searches were performed in databases (PubMed, Web of Science TM , Scopus and Google Scholar), for the period from January 1990 to May 2015. The study analysis was conducted through a critical review of contents. Of the 1 112 articles identified, 1 091 were excluded and 21 met the selection criteria, including 16 articles evaluating BP, 19 articles evaluating HR and four articles evaluating RPP. Divergent results were found when comparing the LI protocols with BFR versus LI versus high intensity (HI) on BP, HR and RPP. The evidence shows that the protocols using continuous BFR following a LIRT session apparently raise HR, BP and RPP compared with LI protocols without BFR, although increases significantly in BP seem to exist between the HI protocols when compared to LI protocols. Haemodynamic changes (HR, SBP, DBP, MBP, RPP) promoted by LIRT with BFR do not seem to differ between ages and body segments (upper or lower), although they are apparently affected by the width of the cuff and are higher with continuous BFR. However, these changes are within the normal range, rendering this method safe and feasible for special populations.
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PURPOSE: The primary objective of this study was to investigate and compare the effects of 5 weeks resistance training protocols (i.e., low-load blood flow restriction resistance training and moderate-load resistance training) especially on blood lipids, muscle strength, anaerobic power and body composition in young normal weight obese women. METHODS: Twenty-nine young normal weight obese women were randomly divided into three groups: blood flow restriction resistance training (BFR-RT, n=9), resistance training (RT, n=10) and non-training control (CON, n=10). BFR-RT group fitted a pneumatic cuff over the upper and lower extremities by using Kaatsu Nano equipment to apply the same pressures with each systolic blood pressure. The subjects in the BFR-RT group performed the training with 40% of 1RM and the RT group executed the resistance training with their 60-70% of 1RM. Both groups had performed the resistance training protocols twice per week for 5 weeks, and each training protocol consisted of bench press, barbell row, squat, and lunge. RESULTS: There were no changes in body weight, fat mass, BMI and %body fat in all groups after interventions for 5 weeks. However, the anaerobic power was significantly increased in both BFR-RT and RT groups compared to the CON group. Interestingly, only in the RT group, muscle mass and high-density lipoprotein cholesterol were significantly increased after the intervention. CONCLUSIONS: In conclusion, this study suggests that moderate-intensity RT is better than low-intensity BFR-RT to improve muscle mass and high-density lipoprotein cholesterol in young normal weight obese women. These authors contributed equally to conduct of the studies. This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (https://creativecommons.org/licenses/by-nc/4.0/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.
Article
PURPOSE:The primary objective of this study was to investigate and compare the effects of 5 weeks resistance training protocols (i.e., low-load blood flow restriction resistance training and moderate-load resistance training) especially on blood lipids, muscle strength, anaerobic power and body composition in young normal weight obese women.METHODS: Twenty-nine young normal weight obese women were randomly divided into three groups: blood flow restriction resistance training (BFR-RT, n=9), resistance training (RT, n=10) and non-training control (CON, n=10). BFR-RT group fitted a pneumatic cuff over the upper and lower extremities by using Kaatsu Nano equipment to apply the same pressures with each systolic blood pressure. The subjects in the BFR-RT group performed the training with 40% of 1RM and the RT group executed the resistance training with their 60-70% of 1RM. Both groups had performed the resistance training protocols twice per week for 5 weeks, and each training protocol consisted of bench press, barbell row, squat, and lunge.RESULTS:There were no changes in body weight, fat mass, BMI and %body fat in all groups after interventions for 5 weeks. However, the anaerobic power was significantly increased in both BFR-RT and RT groups compared to the CON group. Interestingly, only in the RT group, muscle mass and high-density lipoprotein cholesterol were significantly increased after the intervention.CONCLUSIONS: In conclusion, this study suggests that moderate-intensity RT is better than low-intensity BFR-RT to improve muscle mass and high-density lipoprotein cholesterol in young normal weight obese women.
Article
The purpose of the present study was to examine the acute changes in muscle swelling (as assessed by muscle thickness and echo intensity) and muscle blood flow associated with an acute bout of low-load blood flow restriction (LLBFR) and low-load non-blood flow restriction (LL) exercise. Twenty women (mean±SD;22±2yrs) volunteered to perform an acute exercise bout that consisted of 75 (1×30, 3×15) isokinetic, reciprocal, concentric-only, submaximal (30% of peak torque), forearm flexion and extension muscle actions. Pretest, immediately after (posttest), and 5-min after (recovery) completing the 75 repetitions, muscle thickness and echo intensity were assessed from the biceps brachii and triceps brachii muscles and muscle blood flow was assessed from the brachial artery. There were no between group differences for any of the dependent variables, but there were significant simple and main effects for muscle and time. Biceps and triceps brachii muscle thickness increased from pretest (2.13±0.39 cm and 1.88±0.40cm, respectively) to posttest (2.58±0.49cm and 2.17±0.43cm, respectively) for both muscles and remained elevated for the biceps brachii (2.53±0.43cm), but partially returned to pretest levels for the triceps brachii (2.06±0.41cm). Echo intensity and muscle blood flow increased from pretest (98.0±13.6Au and 94.5±31.6mL·min-1 , respectively) to posttest (109.2±16.9Au and 312.2±106.5mL·min-1 , respectively) and pretest to recovery (110.1±18.3Au and 206.7±92.9mL·min-1 , respectively) and remained elevated for echo intensity, but partially returned to pretest levels for muscle blood flow. The findings of the present study indicated that LLBFR and LL elicited comparable acute responses as a result of reciprocal, concentric-only, forearm flexion and extension muscle actions.
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Background: Blood flow restriction (BFR) training has been reported to have significant benefits on local skeletal muscle including increasing local muscle mass, strength, and endurance while exercising with lower resistance. As a result, patients unable to perform traditional resistance training may benefit from this technique. However, it is unclear what effects BFR may have on other body systems, such as the cardiovascular and pulmonary systems. It is important to explore the systemic effects of BFR training to ensure it is safe for use in physical therapy. Purpose: The purpose of this study was to systematically review the systemic effects of blood flow restriction training when combined with exercise intervention. Study design: Systematic review. Methods: Three literature searches were performed: June 2019, September 2019, and January 2020; using MedLine, ScienceDirect, PubMed, Cochrane Reviews and CINAHL Complete. Inclusion criteria included: at least one outcome measure addressing a cardiovascular, endocrinological, systemic or proximal musculoskeletal, or psychosocial outcome, use of clinically available blood flow restriction equipment, use of either resistance or aerobic training in combination with BFR, and use of quantitative measures. Exclusion criteria for articles included only measuring local or distal musculoskeletal changes due to BFR training, examining only passive BFR or ischemic preconditioning, articles not originating from a scholarly peer-reviewed journal, CEBM level of evidence less than two, or PEDro score less than four. Articles included in this review were analyzed with the CEBM levels of evidence hierarchy and PEDro scale. Results: Thirty-five articles were included in the review. PEDro scores ranged between 4 and 8, and had CEBM levels of evidence of 1 and 2. Common systems studied included cardiovascular, musculoskeletal, endocrine, and psychosocial. This review found positive or neutral effects of blood flow restriction training on cardiovascular, endocrinological, musculoskeletal, and psychosocial outcomes. Conclusions: Although BFR prescription parameters and exercise interventions varied, the majority of included articles reported BFR training to produce favorable or non-detrimental effects to the cardiovascular, endocrine, and musculoskeletal systems. This review also found mixed effects on psychosocial outcomes when using BFR. Additionally, this review found no detrimental outcomes directly attributed to blood flow restriction training on the test subjects or outcomes tested. Thus, BFR training may be an effective intervention for patient populations that are unable to perform traditional exercise training with positive effects other than traditional distal muscle hypertrophy and strength and without significant drawbacks to the individual. Level of evidence: 1b.
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Background Muscle atrophy is common after an injury to the knee and anterior cruciate ligament reconstruction (ACLR). Blood flow restriction therapy (BFR) combined with low-load resistance exercise may help mitigate muscle loss and improve the overall condition of the lower extremity (LE). Purpose To determine whether BFR decreases the loss of LE lean mass (LM), bone mass, and bone mineral density (BMD) while improving function compared with standard rehabilitation after ACLR. Study Design Randomized controlled clinical trial Methods A total of 32 patients undergoing ACLR with bone-patellar tendon-bone autograft were randomized into 2 groups (CONTROL: N = 15 [male = 7, female = 8; age = 24.1 ± 7.2 years; body mass index [BMI] = 26.9 ± 5.3 kg/m2] and BFR: N = 17 [male = 12, female = 5; age = 28.1 ± 7.4 years; BMI = 25.2 ± 2.8 kg/m2]) and performed 12 weeks of postsurgery rehabilitation with an average follow-up of 2.3 ± 1.0 years. Both groups performed the same rehabilitation protocol. During select exercises, the BFR group exercised under 80% arterial occlusion of the postoperative limb (Delfi tourniquet system). BMD, bone mass, and LM were measured using DEXA (iDXA, GE) at presurgery, week 6, and week 12 of rehabilitation. Functional measures were recorded at week 8 and week 12. Return to sport (RTS) was defined as the timepoint at which ACLR-specific objective functional testing was passed at physical therapy. A group-by-time analysis of covariance followed by a Tukey’s post hoc test were used to detect within- and between-group changes. Type I error; α = 0.05. Results Compared with presurgery, only the CONTROL group experienced decreases in LE-LM at week 6 (−0.61 ± 0.19 kg, −6.64 ± 1.86%; P < 0.01) and week 12 (−0.39 ± 0.15 kg, −4.67 ± 1.58%; P = 0.01) of rehabilitation. LE bone mass was decreased only in the CONTROL group at week 6 (−12.87 ± 3.02 g, −2.11 ± 0.47%; P < 0.01) and week 12 (−16.95 ± 4.32 g,−2.58 ± 0.64%; P < 0.01). Overall, loss of site-specific BMD was greater in the CONTROL group ( P < 0.05). Only the CONTROL group experienced reductions in proximal tibia (−8.00 ± 1.10%; P < 0.01) and proximal fibula (−15.0±2.50%, P < 0.01) at week 12 compared with presurgery measures. There were no complications. Functional measures were similar between groups. RTS time was reduced in the BFR group (6.4 ± 0.3 months) compared with the CONTROL group (8.3 ± 0.5 months; P = 0.01). Conclusion After ACLR, BFR may decrease muscle and bone loss for up to 12 weeks postoperatively and may improve time to RTS with functional outcomes comparable with those of standard rehabilitation.
Article
Background The precise calculation of arterial occlusive pressure is essential to accurately prescribe individualized pressures during blood flow restriction training. Arterial occlusion pressure in the lower limb varies significantly between different body positions while similar reports for the upper limb are lacking. Hypothesis Body position has a significant effect in upper limb arterial occlusive pressure. Using cuffs with manual pump and a handheld Doppler ultrasound can be a reliable method to determine upper limb arterial blood flow restriction. Study Design A randomized repeated measures design. Level of Evidence Level 3. Methods Forty-two healthy participants (age mean ± SD = 28.1 ± 7.7 years) completed measurements in supine, seated, and standing position by 3 blinded raters. A cuff with a manual pump and a handheld acoustic ultrasound were used. The Wilcoxon signed-rank test with Bonferroni correction was used to analyze differences between body positions. A within-subject coefficient of variation and an intraclass correlation coefficient (ICC) test were used to calculate reproducibility and reliability, respectively. Results A significantly higher upper limb arterial occlusive pressure was found in seated compared with supine position ( P < 0.031) and in supine compared with standing position ( P < 0.031) in all raters. An ICC of 0.894 (95% CI = 0.824-0.939, P < 0.001) was found in supine, 0.973 (95% CI = 0.955-0.985, P < 0.001) in seated, and 0.984 (95% CI = 0.973-0.991, P < 0.001) in standing position. ICC for test-retest reliability was found 0.90 (95% CI = 0.814-0.946, P < 0.001), 0.873 (95% CI = 0.762-0.93, P < 0.001), and 0.858 (95% CI = 0.737-0.923, P < 0.001) in the supine, seated, and standing position, respectively. Conclusion Upper limb arterial occlusive pressure was significantly dependent on body position. The method showed excellent interrater reliability and repeatability between different days. Clinical Relevance Prescription of individualized pressures during blood flow restriction training requires measurement of upper limb arterial occlusive pressure in the appropriate position. The use of occlusion cuffs with a manual pump and a handheld Doppler ultrasound showed excellent reliability; however, the increased measurement error compared with the differences in arterial occlusive pressure between certain positions should be carefully considered for the clinical application of the method. Strength of Recommendations Taxonomy (SORT) B.
Article
The proven beneficial effects of low-load blood flow restriction training on strength gain has led to further exploration into its application during rehabilitation, where the traditional use of heavy loads may not be feasible. With current evidence showing that low-load blood flow restriction training may be less well tolerated than heavy-load resistance training, this review was conducted to decipher whether intermittently deflating the pressure cuff during rest intervals of a training session improves tolerance to exercise, without compromising strength. Four databases were searched for randomized controlled trials that compared the effect of intermittent versus continuous blood flow restriction training on outcomes of exercise tolerance or strength in adults. Nine studies were identified, with six included in the meta-analysis. No significant difference in rate of perceived exertion was found (SMD-0.06, 95% CI-0.41 to 0.29, p=0.73, I 2=80%). Subgroup analysis excluding studies that introduced bias showed a shift towards favoring the use of intermittent blood flow restriction training (SMD-0.42, 95% CI-0.87 to 0.03, p=0.07, I 2=0%). There was no significant difference in strength gain. Intermittent cuff deflations during training intervals does not improve tolerance to exercise during blood flow restriction training.
Thesis
Introdução: Desordens musculoesqueléticas são comuns e podem comprometer a função, o desempenho físico e a qualidade de vida. Dentre as intervenções utilizadas no manejo de desordens musculoesqueléticas, as modalidades de restrição de fluxo sanguíneo (RFS) vêm ganhando espaço na literatura científica. Objetivos: Essa tese teve o propósito de investigar os aspectos fisiológicos, os métodos de prescrição e as aplicações clínicas de modalidades de RFS em diferentes desordens musculoesqueléticas. Métodos e resultados: As modalidades de RFS consideradas foram a RFS passiva (sem exercício concomitante), o pré-condicionamento isquêmico (PCI) e a RFS combinada ao exercício. Como desordens musculoesqueléticas foram consideradas condições que causassem prejuízo funcional, tais como perda de força e de massa muscular, dano muscular induzido por exercício, fadiga muscular e osteoartrite (OA) de joelho. A presente tese é composta por introdução, três capítulos referentes às modalidades de RFS, e considerações finais. Os capítulos 1, 2 e 3 versam, respectivamente, sobre RFS passiva, PCI e RFS combinada ao exercício, e são compostos de sete artigos científicos envolvendo três desenhos de estudo: revisão sistemática (com e sem meta-análise), revisão narrativa e ensaio clínico aleatorizado. O capítulo 1 é uma revisão sistemática (artigo 1) sobre os efeitos da RFS passiva para minimizar perdas de força e de massa muscular (hipotrofia por desuso) em indivíduos submetidos a restrições na descarga de peso em membros inferiores. No capítulo 1 observamos que embora potencialmente útil, o alto risco de viés apresentado nos estudos originais limita a indicação de RFS passiva como modalidade eficaz contra a redução de força e de massa muscular induzida por imobilismo. O capítulo 2 é um ensaio clínico controlado e aleatorizado (artigo 2) que investigou os efeitos do PCI na proteção contra o dano muscular induzido por exercício (DMIE) em pessoas saudáveis. O artigo 2 apontou que o PCI não foi superior ao sham para proteger contra o DMIE. O capítulo 3 aborda aspectos fisiológicos, metodológicos e clínicos da RFS combinada ao exercício físico. O primeiro manuscrito do capítulo 3 (artigo 3) é uma revisão sistemática com meta-análise que analisou a excitação muscular (por eletromiografia de superfície) durante exercício resistido com RFS. O artigo 3 indicou que a excitação muscular durante o exercício de baixa carga com RFS foi maior que durante exercício de carga pareada sem RFS somente quando a falha muscular não foi alcançada. Adicionalmente, exercício de baixa carga com RFS apresentou menor excitação muscular que exercício de alta carga, independentemente de alcançar ou não a falha voluntária. O segundo manuscrito do capítulo 3 (artigo 4) é uma revisão sistemática com meta-análise que mostrou uma viii antecipação da falha muscular durante exercícios de baixa carga com altas pressões de RFS, mas não com baixas pressões. O terceiro manuscrito do capítulo 3 (artigo 5) é uma revisão narrativa que discute a possível necessidade de ajustar a pressão de RFS ao longo das semanas de treinamento. No artigo 5 observamos que a literatura é contraditória, o que dificulta recomendar se tais ajustes na pressão de RFS são necessários. O artigo 6 é um protocolo de ensaio clínico aleatorizado proposto para investigar os efeitos do exercício de baixa carga e volume total reduzido com RFS versus treinamento de alta carga sem RFS no tratamento da OA de joelho. O artigo 7 é o ensaio clínico aleatorizado que apresenta os resultados do protocolo (artigo 6) e mostrou que o treinamento de baixa carga com volume total reduzido e com RFS teve efeito similar ao treinamento de alta carga sem RFS na dor no joelho, desempenho muscular, função física e qualidade de vida de pacientes com OA de joelho, embora a magnitude nos ganhos de força tenha sido maior após treino de alta carga. Conclusões: De forma geral, com exceção do PCI para proteger contra o DMIE, as modalidades de RFS são potencialmente úteis no manejo das disfunções musculoesqueléticas aqui estudadas. Adicionalmente, concluímos que é necessário avançar no entendimento dos mecanismos fisiológicos e no estudo dos métodos de prescrição das diferentes modalidades de restrição de fluxo sanguíneo.
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Purpose: The effects of short-term blood flow restriction (BFR) exercise on muscle blood flow perfusion and performance during high-intensity exercise were determined in elite para-alpine standing skiers to assess whether this would be an effective training regimen for elite athletes with disabilities. Methods: Nine national-level para-alpine standing skiers (mean age, 20.67 ± 1.34 y; four women) were recruited. Non-dominant lower limbs were trained with BFR (eight in final analyses); dominant lower limbs without BFR (seven in final analyses). The 2-week protocol included high-load resistance, local muscle endurance (circuit resistance training), and aerobic endurance (stationary cycling) training performed 4 times/wk, with BFR during local muscle endurance and aerobic endurance sessions. Muscle strength was measured by maximal voluntary isometric contraction (MVIC) in the knee extensors; microcirculatory blood perfusion (MBP), by laser doppler blood flow; and muscle strength and endurance, by the total amount of work (TW) performed during high-intensity centrifugal and concentric contractions. Results: BFR significantly increased absolute and relative MVIC (P < 0.001, P = 0.001), MBP (P = 0.011, P = 0.008), and TW (P = 0.006, P = 0.007) from pretraining values, whereas only absolute MVIC increased without BFR (P = 0.047). However, the MVIC increase with BFR exercise (35.88 ± 14.83 N·m) was significantly greater (P = 0.040) than without BFR exercise (16.71 ± 17.79 N·m). Conclusions: Short-term BFR exercise significantly increased strength endurance, muscle strength, and microcirculatory blood perfusion in national-level para-alpine standing skiers. Our study provides new evidence that BFR exercise can improve local muscle blood perfusion during high-intensity exercise and informs BFR exercise strategies for athletes with disabilities.
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This review paper outlines the effect of blood flow restriction exercise on hemodynamics from the biomechanical perspective. Blood flow restriction exercise is a kind of exercise methods that maximizes the effectiveness of exercise by applying specific pressure to block vein flow while allowing flow of arteries by wearing portable pneumatic cuffs in the upper and lower parts of the body prior to exercise. In various existing literature, the effect of blood flow restriction on exercise has been revealed based on lots of field including elite sports, recreation, and rehabilitation. This study will establish the concept of blood flow restriction on exercise by integrating the contents of such research. Therefore, the purpose of this study is to provide information based on scientific evidence on blood flow restriction exercise by introducing the concept and principle of blood flow restriction, physiological mechanisms and effects, actual application cases, and precautions.
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TGFbeta signaling is initiated when the type I receptor phosphorylates the MAD-related protein, Smad2, on C-terminal serine residues. This leads to Smad2 association with Smad4, translocation to the nucleus, and regulation of transcriptional responses. Here we demonstrate that Smad7 is an inhibitor of TGFbeta signaling. Smad7 prevents TGFbeta-dependent formation of Smad2/Smad4 complexes and inhibits the nuclear accumulation of Smad2. Smad7 interacts stably with the activated TGFbeta type I receptor, thereby blocking the association, phosphorylation, and activation of Smad2. Furthermore, mutations in Smad7 that interfere with receptor binding disrupt its inhibitory activity. These studies thus define a novel function for MAD-related proteins as intracellular antagonists of the type I kinase domain of TGFbeta family receptors.
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Myostatin is a transforming growth factor-beta family member that acts as a negative regulator of skeletal muscle mass. To identify possible myostatin inhibitors that may have applications for promoting muscle growth, we investigated the regulation of myostatin signaling. Myostatin protein purified from mammalian cells consisted of a noncovalently held complex of the N-terminal propeptide and a disulfide-linked dimer of C-terminal fragments. The purified C-terminal myostatin dimer was capable of binding the activin type II receptors, Act RIIB and, to a lesser extent, Act RIIA. Binding of myostatin to Act RIIB could be inhibited by the activin-binding protein follistatin and, at higher concentrations, by the myostatin propeptide. To determine the functional significance of these interactions in vivo, we generated transgenic mice expressing high levels of the propeptide, follistatin, or a dominant-negative form of Act RIIB by using a skeletal muscle-specific promoter. Independent transgenic mouse lines for each construct exhibited dramatic increases in muscle mass comparable to those seen in myostatin knockout mice. Our findings suggest that the propeptide, follistatin, or other molecules that block signaling through this pathway may be useful agents for enhancing muscle growth for both human therapeutic and agricultural applications.
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BOLSTER, D. R., S. R. KIMBALL, and L. S. JEFFERSON. Translational control mechanisms modulate skeletal muscle gene expression during hypertrophy. Exerc. Sport Sci. Rev., Vol. 31, No. 3, pp. 111–116, 2003. Understanding the basic mechanisms regulating skeletal muscle hypertrophy is essential to providing strategies for optimizing and maintaining skeletal muscle mass. This review focuses on the importance of mRNA translation in mediating acute increases in protein synthesis after resistance exercise as well as the anabolic response of muscle growth.
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Myostatin is a negative regulator of muscle mass and its effects seem to be exacerbated by glucocorticoids; however, its response to resistance training is not well known. This study examined 12 wk of resistance training on the mRNA and protein expression of myostatin, follistatin-like related gene (FLRG), activin IIb receptor, cortisol, glucocorticoid receptor, myofibrillar protein, as well as the effects on muscle strength and mass and body composition. Twenty-two untrained males were randomly assigned to either a resistance-training [RTR (N = 12)] or control group [CON (N = 10)]. Muscle biopsies and blood samples were obtained before and after 6 and 12 wk of resistance training. RTR trained 3 x wk(-1) using three sets of six to eight repetitions at 85-90% 1-RM on lower-body exercises, whereas CON performed no resistance training. Data were analyzed with two- and three-way ANOVA. After 12 wk of training, RTR increased total body mass, fat-free mass, strength, and thigh volume and mass; however, they increased myostatin mRNA, myostatin, FLRG, cortisol, glucocorticoid receptor, and myofibrillar protein after 6 and 12 wk of training (P < 0.05). Resistance training and/or increased glucocorticoid receptor expression appears to up-regulate myostatin mRNA expression. Furthermore, it is possible that any plausible decreases in skeletal muscle function from the observed increase in serum myostatin were attenuated by increased serum FLRG levels and the concomitant down-regulation of the activin IIb receptor. It is therefore concluded that the increased myostatin in response to cortisol and/or resistance training appears to have no effects on training-induced increases in muscle strength and mass.
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We determined and compared the magnitude of changes in resting plasma myostatin and IGF-1, muscle strength, and size in response to whole body or local muscle resistance training in healthy men. Volunteers performed high-intensity resistance exercise of major muscle groups of the whole body (N = 11), or of the elbow flexors only (N = 6), twice per week for 10 wk. Strength was assessed by elbow flexor one-repetition maximum (1-RM) and repetitions at 80% of 1-RM, muscle cross-sectional area by MRI, and plasma IGF-1 by RIA and myostatin by Western analyses, before and after the training program. In subjects of both groups, elbow flexor 1-RM and cross-sectional area increased (P = 0.05) by 30 +/- 8% (mean +/- SD) and 12 +/- 4%, respectively. Individual changes in myostatin ranged from 5.9 to -56.9%, with a mean decrease of 20 +/- 16%, whereas IGF-1 did not change from pre- to posttraining. There were no significant differences in any of the responses of the subjects between the two training programs. Myostatin may play a role in exercise-induced increases in muscle size, its circulating levels decreasing with resistance training in healthy men. Exercise of the whole body versus the elbow flexors alone did not provide a supplementary stimulus in altering resting plasma IGF-1 or myostatin, or in increasing muscle strength or size. Thus, by default, growth factor responses local to the muscle may be more important than circulating factors in contributing to muscle hypertrophy with resistance training.
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Myostatin is a secreted protein that acts as a negative regulator of skeletal muscle mass. During embryogenesis, myostatin is expressed by cells in the myotome and in developing skeletal muscle and acts to regulate the final number of muscle fibers that are formed. During adult life, myostatin protein is produced by skeletal muscle, circulates in the blood, and acts to limit muscle fiber growth. The existence of circulating tissue-specific growth inhibitors of this type was hypothesized over 40 years ago to explain how sizes of individual tissues are controlled. Skeletal muscle appears to be the first example of a tissue whose size is controlled by this type of regulatory mechanism, and myostatin appears to be the first example of the long-sought chalone.