Strypträning ftw?

[ozzian]

med risk att verka dum:
vad skiljer en sån här åtsnörpning mot occulationsträning?

[King Grub]

This study ascertains the ability of bodyweight blood flow-restricted (BFR) exercise training to promote skeletal muscle adaptations of significance for muscle accretion and metabolism. Six healthy young individuals (three males and three females) performed six weeks of bodyweight BFR training. Each session consisted of five sets of sit-to-stand BFR exercise to volitional failure with 30-second inter-set recovery. Prior to, and at least 72 h after training, muscle biopsies were taken from m. vastus lateralis to assess changes in fibre type-specific cross-sectional area (CSA), satellite cell (SC) and myonuclei content and capillarization, as well as mitochondrial protein expression. Furthermore, magnetic resonance imaging was used to assess changes in whole thigh muscle CSA. Finally, isometric knee extensor muscle strength was evaluated. An increase in knee extensor whole muscle CSA was observed at middle and distal localizations after training (3·2% and 3·5%, respectively) (P<0·05), and a trend was observed towards an increase in type I fibre CSA, whereas muscle strength did not increase. Additionally, the number of SCs and myonuclei associated with type I fibres increased by 65·7% and 20%, respectively (P<0·05). No significant changes were observed in measures of muscle capillarization and mitochondrial proteins. In conclusion, six weeks of bodyweight-based BFR exercise promoted myocellular adaptations related to muscle accretion, but not metabolic properties. Moreover, the study revealed that an appropriate total training volume needs further investigation before recommending bodyweight BFR to patient populations.

Clin Physiol Funct Imaging. 2018 Feb 15. Impact of blood flow-restricted bodyweight exercise on skeletal muscle adaptations.

[King Grub]

Low-load blood flow restricted (BFR) resistance exercise has been suggested to be as effective as moderate and high-load resistance training for increasing muscle size and strength. The purpose of the study was to evaluate the effects of 6 weeks of HL or low-load BFR resistance training on neuromuscular function, strength, and hypertrophy of the knee extensors. Eighteen participants aged 18-22 years old were randomized to one of three training groups: moderate load (ML: 70% of 1 repetition maximum [1-RM]); BFR (20% 1-RM with a vascular restriction set to ~180 mmHg); and a control group (CON) that did not exercise. Participants performed leg extension (LE) and leg press exercises 3 times per week for 6 weeks. Measurements of isometric torque, LE 1-RM, central activation, electrically evoked torque, and muscle volume of the knee extensors were obtained before and after training. Isometric peak torque did not change following the training (p = 0.13). LE 1-RM improved in the ML (34 ± 20%; d = 0.78) and BFR (14 ± 5%; d = 0.67) groups compared to the CON group (0.6 ± 8%; d = 0.09; time x group interaction p = 0.02). Muscle volume increased in the ML (5.6%; d = 0.19) and BFR groups (2.5%; d = 0.09) with no change in the CON group (time x group interaction p = 0.001). There were no changes in central activation and evoked torque in any groups following the training (p > 0.05). Strength and hypertrophy were evident following ML and BFR resistance training programs indicating that both modalities are effective, although ML training appears to be a more potent and efficient. Neuromuscular changes were not evident and warrant more research.

J Sports Sci Med. 2018 Mar 1;17(1):66-73. Neuromuscular Adaptations to Low-Load Blood Flow Restricted Resistance Training.

[Torsk_ole]

Har testat att köra lite senaste veckan. Armar och vader. Kör efter mitt vanliga pass. Träningsvärken är helt orimlig, 4 dagar efter så känns det fortfarande i armarna.

[Slartibartfast]

Var ska man strypa åt när man tränar vaderna? Lyssnade på en pod med Mike Zourdos, som sa att man inte ska strypa nedanför knät, utan alltid högst uppe på låret. Vad är det som gäller?

[King Grub]

Blood flow-restricted resistance (BFRR) training is effective as a means to improve muscle strength and size while enduring less mechanical stress. It is generally safe but can have adverse effects. We present a case of an active duty Soldier who developed rhabdomyolysis as a result of a single course of BFRR training. He was presented to the emergency department with bilateral lower extremity pain, was admitted for electrolyte monitoring and rehydration, and had an uncomplicated hospital course and full recovery. This is an increasingly common mode of rehabilitation in the military, and practitioners and providers should be aware of it and its possible adverse effects.

J Spec Oper Med. 2018 Summer;18(2):16-17. A Case of Rhabdomyolysis Caused by Blood Flow-Restricted Resistance Training.

[Termy]

Jeffries O, Waldron M, Pattison JR, Patterson SD. Enhanced Local Skeletal Muscle Oxidative Capacity and Microvascular Blood Flow Following 7-Day Ischemic Preconditioning in Healthy Humans. Frontiers in Physiology. 2018;9:463. doi:10.3389/fphys.2018.00463. Fulltext.

Abstract


Ischemic preconditioning (IPC), which involves intermittent periods of ischemia followed by reperfusion, is an effective clinical intervention that reduces the risk of myocardial injury and confers ischemic tolerance to skeletal muscle. Repeated bouts of IPC have been shown to stimulate long-term changes vascular function, however, it is unclear what metabolic adaptations may occur locally in the muscle. Therefore, we investigated 7 days of bilateral lower limb IPC (4 × 5 min) above limb occlusion pressure (220 mmHg; n = 10), or sham (20 mmHg; n = 10), on local muscle oxidative capacity and microvascular blood flow. Oxidative capacity was measured using near-infrared spectroscopy (NIRS) during repeated short duration arterial occlusions (300 mmHg). Microvascular blood flow was assessed during the recovery from submaximal isometric plantar flexion exercises at 40 and 60% of maximal voluntary contraction (MVC). Following the intervention period, beyond the late phase of protection (72 h), muscle oxidative recovery kinetics were speeded by 13% (rate constant pre 2.89 ± 0.47 min-1 vs. post 3.32 ± 0.69 min-1; P < 0.05) and resting muscle oxygen consumption (m

O2) was reduced by 16.4% (pre 0.39 ± 0.16%.s-1 vs. post 0.33 ± 0.14%.s-1; P < 0.05). During exercise, changes in deoxygenated hemoglobin (HHb) from rest to steady state were reduced at 40 and 60% MVC (16 and 12%, respectively, P < 0.05) despite similar measures of total hemoglobin (tHb). At the cessation of exercise, the time constant for recovery in oxygenated hemoglobin (O2Hb) was accelerated at 40 and 60% MVC (by 33 and 43%, respectively) suggesting enhanced reoxygenation in the muscle. No changes were reported for systemic measures of resting heart rate or blood pressure. In conclusion, repeated bouts of IPC over 7 consecutive days increased skeletal muscle oxidative capacity and microvascular muscle blood flow. These findings are consistent with enhanced mitochondrial and vascular function following repeated IPC and may be of clinical or sporting interest to enhance or offset reductions in muscle oxidative capacity.

[Termy]

Med Sci Sports Exerc. 2018 Sep 4. doi: 10.1249/MSS.0000000000001775. [Epub ahead of print] Type 1 Muscle Fiber Hypertrophy after Blood Flow-restricted Training in Powerlifters. Bjørnsen T1, Wernbom M2, Kirketeig A3, Paulsen G4, Samnøy L3, Bækken L5, Cameron-Smith D6,7,8, Berntsen S1, Raastad T5. Fulltext.

Abstract

PURPOSE:
To investigate the effects of blood flow restricted resistance exercise (BFRRE) on myofiber areas (MFA), number of myonuclei and satellite cells (SC), muscle size and strength in powerlifters. METHODSSeventeen national level powerlifters (25±6 yrs [mean±SD], 15 men) were randomly assigned to either a BFRRE group (n=9) performing two blocks (week 1 and 3) of five BFRRE front squat sessions within a 6.5-week training period, or a conventional training group (Con; n=8) performing front squats at ~70% of one-repetition maximum (1RM). The BFRRE consisted of four sets (first and last set to voluntary failure) at ~30% of 1RM. Muscle biopsies were obtained from m. vastus lateralis (VL) and analyzed for MFA, myonuclei, SC and capillaries. Cross sectional areas (CSA) of VL and m. rectus femoris (RF) were measured by ultrasonography. Strength was evaluated by maximal voluntary isokinetic torque (MVIT) in knee extension and 1RM in front squat.

RESULTS:
BFRRE induced selective type I fiber increases in MFA (BFRRE: 12% vs. Con: 0%, p<0.01) and myonuclear number (BFRRE: 17% vs. Con: 0%, p=0.02). Type II MFA was unaltered in both groups. BFRRE induced greater changes in VL CSA (7.7% vs. 0.5%, p=0.04), which correlated with the increases in MFA of type I fibers (r=0.81, p=0.02). No group differences were observed in SC and strength changes, although MVIT increased with BFRRE (p=0.04), whereas 1RM increased in Con (p=0.02).Two blocks of low-load BFRRE in the front squat exercise resulted in increased quadriceps CSA associated with preferential hypertrophy and myonuclear addition in type 1 fibres of national level powerlifters.

[King Grub]

PURPOSE:

The purpose of this study was to identify whether post-resistance exercise (REx) blood flow restriction (BFR) can elicit a similar acute training stimulus to that offered by either heavy REx or traditional low-load BFR REx.

METHOD:

Ten men completed trials with 30% one-repetition maximum (1RM) for 5 sets of 15 repetitions without BFR (30%), with BFR during exercise (30% RD), and with postexercise BFR (30% RP) and at 75% 1RM for 3 sets of 10 repetitions. Lactate and cortisol were measured before and up to 60 min after exercise. Thigh circumference, ratings of perceived exertion (RPE), and pain were measured before and after exercise. Surface electromyography was measured during exercise.

RESULTS:

All conditions had a large effect (effect size [ES] > 0.8) on lactate, with the largest effects observed with the 75% condition; no differences were observed between the 30% conditions. All conditions had a moderate effect (ES > 0.25 ≤ 0.4) on increasing thigh circumference. This effect was maintained (ES = 0.35) with the application of BFR after REx (30% RP). Change in RPE, from the first to last set, was significantly greater with 30% RD compared with other conditions (all p < .05). Electromyography amplitude was higher and percentage change was greater for the 75% condition compared with the other conditions (both p < .05).

CONCLUSIONS:

The application of BFR immediately post-REx altered several of the responses associated with REx that is aimed at inducing muscular hypertrophy. Additionally, these changes occurred with less pain and perceived exertion suggesting that this form of REx may offer an alternative, tolerable method of REx.

Res Q Exerc Sport. 2018 Sep 21:1-7. Is Postexercise Blood Flow Restriction a Viable Alternative to Other Resistance Exercise Protocols?

[Scratch89]

Ouff vad jobbigt att köra strypträning på 75% av 1 RM.

[King Grub]

BACKGROUND:

The combination of low-load resistance training with blood flow restriction (BFR) has recently been shown to promote muscular adaptations in various populations. To date, however, evidence is sparse on how this training regimen influences muscle mass and strength in older adults.

PURPOSE:

The purpose of this systematic review and meta-analysis was to quantitatively identify the effects of low-load BFR (LL-BFR) training on muscle mass and strength in older individuals in comparison with conventional resistance training programmes. Additionally, the effectiveness of walking with and without BFR was assessed.

METHODS:

A PRISMA-compliant systematic review and meta-analysis was conducted. The systematic literature research was performed in the following electronic databases from inception to 1 June 2018: PubMed, Web of Science, Scopus, CINAHL, SPORTDiscus and CENTRAL. Subsequently, a random-effects meta-analysis with inverse variance weighting was conducted.

RESULTS:

A total of 2658 articles were screened, and 11 studies with a total population of N = 238 were included in the meta-analysis. Our results revealed that during both low-load training and walking, the addition of BFR elicits significantly greater improvements in muscular strength with pooled effect sizes (ES) of 2.16 (95% CI 1.61 to 2.70) and 3.09 (95% CI 2.04 to 4.14), respectively. Muscle mass was also increased when comparing walking with and without BFR [ES 1.82 (95% CI 1.32 to 2.32)]. In comparison with high-load training, LL-BFR promotes similar muscle hypertrophy [ES 0.21 (95% CI - 0.14 to 0.56)] but lower strength gains [ES - 0.42 (95% CI - 0.70 to - 0.14)].

CONCLUSION:

This systematic review and meta-analysis reveals that LL-BFR and walking with BFR is an effective interventional approach to stimulate muscle hypertrophy and strength gains in older populations. As BFR literature is still scarce with regard to potential moderator variables (e.g. sex, cuff pressure or training volume/frequency), further research is needed for strengthening the evidence for an effective application of LL-BFR training in older people.

Sports Med. 2018 Oct 10. Effects of Blood Flow Restriction Training on Muscular Strength and Hypertrophy in Older Individuals: A Systematic Review and Meta-Analysis.

[Termy]

Clin J Sport Med. 2018 Nov;28(6):491-492. doi: 10.1097/JSM.0000000000000488. Risks of Exertional Rhabdomyolysis With Blood Flow-Restricted Training: Beyond the Case Report. Thompson KMA1, Slysz JT, Burr JF.
https://docdro.id/cvIdQoN

Lite uttdrag (kort artikel dock):

It is our opinion that there is currently a lack of evidence to suggest that the practice of BFR training significantly increases the risk of ER in comparison with any other physical activity; however, we agree with Clark and Manini that the use of low- load exercise does not negate the possibility of ER-related complications, and that the additional stress imposed on the
body by the BFR must be considered.

Therefore, we suggest that individuals must be screened more thoroughly
before BFR training. In fact, at least one of the 3 currently published case reports specifically notes that exacerbation of ER was likely through a combination of excessive stress, bacterial infection, and medication.

It is logical to assume that repeated bouts of BFR training, if performed at the optimal dosage (volume and intensity) with appropriate recovery among exercise bouts, will generate a protective effect against ischemic exercise, or other bodily insult, in a similar way that chronic endurance exercise reduces cardiovascular disease risk factors.

[King Grub]

Low-load blood flow restricted resistance exercise (BFRE) performed to volitional failure is suggested to constitute an effective method for producing increases in muscle size and function. However, failure BFRE may entail high levels of perceived exertion, discomfort and/or delayed onset of muscle soreness (DOMS). The aim of the study was to compare BFRE performed to volitional failure (F-BFRE) vs non-failure BFRE (NF-BFRE) on changes in muscle size, function and perceptual responses. Fourteen young untrained males had one leg randomized to knee-extension F-BFRE while the contralateral leg performed NF-BFRE. The training consisted of 22 training bouts over an 8-week period. Whole-muscle cross-sectional area (CSA) of quadriceps components, muscle function, and DOMS were assessed before and after the training period. Perceived exertion and discomfort were registered during each training bout. Both F-BFRE and NF-BFRE produced regional increases in muscle CSA in the range of; quadriceps (2.5-3.8%), vastus lateralis (8.1-8.5%), and rectus femoris (7.9-25.0%). All without differences between leg. Muscle strength (6.8-11.5%) and strength-endurance capacity (13.9-18.6%) also increased to a similar degree in both legs. Less perceived exertion, discomfort and DOMS were reported with NF-BFRE compared to F-BFRE. In conclusion, non-failure BFRE enable increases in muscle size and muscle function, while involving reduced perceptions of exertion, discomfort and DOMS. Non-failure BFRE may be a more feasible approach in clinical settings.

Scand J Med Sci Sports. 2018 Nov 26. Non-failure blood flow restricted exercise induces similar muscle adaptations and less discomfort than failure protocols.

[King Grub]

Blood flow restriction (BFR) is a novel training method that can elicit training adaptations at low training intensities. Recent research has aimed to determine the effect of aerobic exercise with BFR on aerobic fitness and performance, with conflicting results. This review aimed to systematically identify and assess studies that have combined BFR with aerobic exercise in humans, establishing its effect on aerobic fitness and performance. Five databases (Medline, Web of Science, SPORTDiscus, CINHAL, and ScienceDirect) were searched. Two authors independently conducted all searches and reviewed all abstracts, determining article suitability. The Quality Assessment Tool for Quantitative Studies was used to assess risk of bias in each study. Fourteen studies were included for analysis. Blood flow restriction aerobic exercise increased measures of aerobic fitness and performance in younger adults when using occlusion pressures ≥130 mm Hg. In older adults, measures of aerobic performance improved; however, measures of aerobic fitness remained unchanged. These findings must be interpreted with caution because methodological limitations were present in all trials. Short-term BFR aerobic exercise seems to offer a valid method of improving aerobic performance and fitness in healthy adults when using occlusion pressures ≥130 mm Hg. Conversely, it seems to strictly enhance aerobic performance in older adults without impacting aerobic fitness, potentially suggesting different mechanisms of adaptation between older and younger individuals. Despite methodological limitations, BFR aerobic exercise seems to have applications in scenarios where high-intensity aerobic exercise is not appropriate, although more high-quality research is needed to further demonstrate this.

Effects of Blood Flow Restriction Training on Aerobic Capacity and Performance. The Journal of Strength & Conditioning Research: December 07, 2018.

[Termy]

Delayed myonuclear addition, myofiber hypertrophy and increases in strength with high-frequency low-load blood flow restricted training to volitional failure. J Appl Physiol (1985). 2018 Dec 13. doi: 10.1152/japplphysiol.00397.2018. [Epub ahead of print]

https://www.physiology.org/doi/abs/1...iol.00397.2018

Abstract
PURPOSE: To investigate muscle hypertrophy, strength, myonuclear and satellite cell (SC) responses to high-frequency blood flow restricted resistance exercise (BFRRE).

METHODS: Thirteen individuals (24±2 years [mean ± SD], 9 males) completed two 5-day-blocks of 7 BFRRE sessions, separated by a 10-day rest period. Four sets of unilateral knee extensions to voluntary failure at 20% of 1RM were conducted with partial blood flow restriction (90-100 mmHg). Muscle samples obtained before-, during, 3- and 10 days after training were analyzed for muscle fiber area (MFA), myonuclei, SC, and mRNA and miRNA expression. Muscle size was measured by ultrasonography and magnetic resonance imaging, and strength with 1RM knee-extension.

RESULTS: With the first block of BFRRE, SC number increased in both fiber types (70-80%, p<0.05), while type I and II MFA decreased by 6±7% and 15±11% (p<0.05), respectively. With the second block of training, muscle size increased by 6-8%, while the number of SC (type I: 80±63%, type II 147±95%), myonuclei (type I: 30±24%, type II: 31±28%) and MFA (type I: 19±19%, type II: 11±19%) peaked 10 days after the second block of BFRRE, whereas strength peaked after 20 days of detraining (6±6%, p<0.05). Pax7- and p21 mRNA expression were elevated during the intervention, while myostatin, IGF1R, MyoD, myogenin, cyclinD1 and -D2 mRNA did not change until 3-10 days post intervention.

CONCLUSION: High frequency low-load BFRRE induced robust increases in SC, myonuclei and muscle size, but modest strength gains. Intriguingly, the responses were delayed and peaked 10-20 days after the training intervention, indicating overreaching.