Blood Flow Restriction (BFR) – Blog

The phenomenon of exertion and how to evade excessive discomfort associated with BFR has just recently been explored in a review by Rolnick et al. elaborating on various barriers. In a later post, we summarize these findings including anecdotical tips for successful implementation of BFR training:

➡️ For long-term adherence to BFR training programs, it is imperative to consider that the perceptual demands are elevated compared to most regular resistance training.
Simply put, motivation for any exercise may be attenuated if the initial exercise intensity is too high. So, by starting with less load, time and pressure, you can reduce excessive perceptual demands and foster long-term BFR training compliance.

Regardless of resistance training load, as fatigue accumulates during a set, movement speed involuntarily slows and corollary discharges occur leading to peripheral and central fatigue.
On the other hand, higher Ratings Perceived Exertion (RPE) are needed to improve musculoskeletal outcomes. Because high RPE is needed to maintain similar muscle force output which amplifies the recruitment of additional motor units especially the fast-twitch muscle fibers.

So, using low loads with or without BFR, the amount of RPE can be a surrogate for the effectiveness of a given training stimulus.
In this regard, BFR training has shown to reduce the repetitions needed to reach volitional fatigue, i.e., effective training stimulus. This is because BFR training elicits higher RPE compared to the same number of repetitions with the same load performed without BFR.
During BFR Training to failure, accumulation of metabolites and muscle pain/discomfort are approaching or exceeding high-load training. But on the other hand, seems less compared to low-load training without BFR taking to failure.

For some individuals the discomfort/pain and RPE constitute a barrier for using BFR long-term, that is why a short familiarization period avoiding muscle failure to mitigate the barrier of perceptual responses seems relevant.

To be be continued!

Source: Nicholas Rolnick, Kyle Kimbrell, Mikhail Santos Cerqueira, Ben Weatherford and Christopher Brandner (2021): Perceived Barriers to Blood Flow Restriction Training.

Clael et al. (2021) explored the effect of a single bout of Blood Flow Restriction Training vs high-load training on blood pressure, lactate, blood glucose and cholesterol. The aim the present study was to verify and compare these effects with and without BFR.

Methods: Sample; 10 healthy recreational bodybuilders and physically active male and females, between 18-30 of age.
Study procedures; cross-over study, all volunteers experienced 1 bout of exercise as Low-load BFR vs No-BFR High-load vs control.
BFR and No-BFR groups performing 4 sets of back squats and 4 sets of biceps curls with 60 seconds inter-set rest, all sets were performed to failure.
The BFR group intensity was set at 20% of 1RM with 100 mmHg across all participants with no mention of cuff width for both exercises. No-BFR group intensity was set at 70% of 1RM.

Outcomes: Systolic and diastolic blood pressure pre-exercise, post-exercise and 15, 30, 45 and 60 min. after (Rec).
Glycemia (blood glucose), total cholesterol and lactate pre-exercise, post-exercise and 15 min. after (Rec15).

Results: Not surprisingly lactate production in the BFR group was significantly higher at Rec15 vs control and No-BFR groups.
Blood glucose in the BFR-group and No-BFR experienced a significant drop from pre-exercise to Rec60.
Total cholesterol remained significantly higher in the BFR-group at Rec15 vs control and No-BFR groups.
Not surprisingly both BFR and No-BFR groups significantly increased systolic blood pressure post-exercise vs pre-exercise, with a subsequent drop at Rec15.

Conclusion: Squat and biceps curl exercises with and without BFR elicit similar changes in hemodynamic variables. Furthermore, training with BFR delays blood lactate removal and promotes an increase in total cholesterol vs No-BFR. It seems that BFR has similar positive effects on glucose, lactate, cholesterol and blood pressure vs high-load training.

Limitations: Arbitrary pressure of 100 mmHg used across the board and body parts. In combination with missing information on the cuff width, these results are hard to extrapolate for future research and practical application.

Source:
Clael et al. (2021) Effects of blood flow restriction in large and small muscle groups.

In display You will find the optional constant connected Pressure Gauge for convenient interval-based exercise. Combined with the recent optional longer hose and quick air-release, You have the possibility to swiftly detach and re-attach the Gauge if needed.

In the text below You will find the finale post in the continues series on BFR for performance, as we present the finale findings from the review by Pignanelli et al. (2021).

📍Cardiovascular Adaptations and Fitness:

The cardiovasculature ability to transport O2 from the heart to the microvasculature (VO2max), is determined by Maximal Cardiac output (Q-Max) and Arterial Venous Oxygen transport (A-V O2 difference).

Peripheral adaptations, e.g., increase in artery blood flow, muscle capillary density, and elevated oxidative capacity is probably the most important physical adaptation for increased VO2max following periods of BFR training.

Compared with regular exercise, BFR Training provides a unique blood flow: During BFR, muscle oxygen supply is reduced, which stimulates the release of local vasodilatory substances from the vasculature and muscles. As a result, upon cuff release, a large increase in blood flow elevates vascular shear stress which offer an advantageous stimuli compared to free flow exercise.

Like this example, the response to 6 weeks of BFR bike-interval training, knee-extensor oxygen delivery at a high intensity (90% of incremental peak output) increased by 13% vs free-flow condition ~ 0% (Christiansen 2020).

Different VO2max limitations in endurance-trained vs untrained individuals are interesting because improvements have been observed regardless of exercise mode or intensity in both untrained (Abe 2010), (Conceição 2019), (Oliveira 2016) and well-trained (Held 2019), (Mitchell 2019), (Taylor 2016).

In support of central cardiovascular improvements, it seems that muscle capillarity or mitochondrial protein content in endurance-trained athletes is not massively improved following sprint-interval BFR Training, despite robust increases in VO2max (Mitchell 2019).

Conclusion and Perspectives:

It remains to be determined how the interaction of BFR and exercise training variables (pressure, intensity, duration, and frequency) influence each distinct adaptation!? Though, for improved muscle oxidative capacity BFR training should be achieved from endurance- and obviously not resistance-type BFR training.

Adaptations to BFR cardio exercise may occur via different mechanisms as interval-type BFR training improves mitochondrial function, whereas continuous, steady-state BFR training may increase mitochondrial content!?

To date, no studies have explored changes in cardiac structure and function following BFR training!?

It is currently unknown how training status influences the response to BFR exercise. Nevertheless, BFR exercise seems to be a relevant add-on for optimizing various parameters of performance regardless of training status.🔥

Primary Source:
Pignalelli et al. (2021) Blood flow restriction training and the high-performance athlete: science to application

Original Papers:
Abe et al. (2010) Effects of low-intensity cycle training with restricted leg blood flow on thigh muscle volume and VO2max in young men.

Conceição et al. (2019) Augmented anabolic responses after 8-wk cycling with blood flow restriction.

Oliveira et al. (2016) Short-term low-intensity blood flow restricted interval training improves both aerobic fitness and muscle strength.

Held et al. (2019) Low intensity rowing with blood flow restriction over 5-weeks increases V-VO2max in elite rowers: a randomized controlled trial.

In this follow up post on the continues series on BFR for performance, we present the findings from the 2. part of the review by Pignanelli et al. (2021).

In display, You will find the updated pressure gauge (Wireless). By pairing this edition with the brand new optional longer hose (2.2 meters / 87 Inch) You got a game changer for interval-based BFR exercise. Because it allows for instant pressure readings and importantly swift inflation and deflation relative to inter-set rest and work periods – BFR cardio exercise has never been more convenient.

📍2. Physiological adaptations following BFR Training.

👉 Muscle Redox and Ionic Buffering:

Muscle fatigue is multifactorial and task-dependent encountered from a range of physical parameters. Optimizing the capacity to maintain redox and ionic homeostasis during exercise is important for athletic performance.

BFR augmented interval running in well trained individuals (>57 VO2-max) increases markers associated with ion transport (Christiansen 2018).

Similar BFR protocols has been used for 6 week of bike-interval training in recreational individuals, which increased the work capacity of the knee extensors 23% vs workmatched control 11%. (Christiansen 2019A, 2019B).

Comparable adaptations seem to improve repeated sprint and general running performance.

👉 Muscle Oxidative Capacity:

High oxidative capacity is imperative for oxygen extraction, to maintain aerobic work and to perform and recover from repeated high-intensity efforts.

Improvements in muscle oxidative capacity has been linked to both mitochondria content and importantly function.

4 week of moderate-intensity bike training (45 min/session) with BFR increased citrate synthase activity +20% compared with the work-matched control (Esbjörnsson 1993).

Favorable effects of BFR-interval training on muscle oxidative capacity have also been explored as 4–6 week of bike-interval training, which improved muscle diffusional O2 conductance (Christiansen 2020) and oxygen kinetics (Corvino 2019).

More to come in this series on the cardiovascular adaptations and future research/perspectives for BFR Training.

Primary Source:
Pignanelli et al (2021) Blood flow restriction training and the high-performance athlete: science to application.

Original papers:

Christiansen et al (2018) Running is related to fibre type-specific AMPK signalling and oxidative stress in human muscle.

Christiansen et al (2019A) Blood flow-restricted training enhances thigh glucose uptake during exercise and muscle antioxidant function in humans.

Christiansen et al (2019B) Cycling with blood flow restriction improves performance and muscle Kþ regulation and alters the effect of anti-oxidant infusion in humans.

Esbjörnsson et al. (1993) Muscle fibre types and enzyme activities after training with local leg ischaemia in man.

Christiansen et al (2020) Training with blood flow restriction increases femoral artery diameter and thigh oxygen delivery during knee-extensor exercise in recreationally trained men.

Corvino et al (2019) Speeding of oxygen uptake kinetics is not different following low-intensity blood-flow-restricted and high-intensity interval training.

In this 1. blog-post in a continues series we present the findings from a newly published review by Pignanelli et al. (2021) on BFR and the high-performance athlete:

The present paper explores 3 domains for BFR and performance:

📍1. The evidence of BFR for improved training adaptations in well-trained individuals.

📍2. Physiological adaptations following BFR Training.

📍3. Identify gaps in the literature and future research directions for BFR.

Introduction: BFR training can improve strength and different parameters of endurance using loads and intensities traditionally incapable of stimulating change in healthy populations.

📍1.
👉BFR Training Adaptations in Strength-Trained and Team-Sport Athletes:

For this domain the authors mention the study by Bjørnsen et al. (2019)

The protocol simply, 2 x 1-weekly blocks consisting of front squats at either alternating low-load (30% 1RM) continuous BFR or high-load vs conventional high-load only.

The addition of 10 BFR sessions increased quadriceps cross-sectional area by 3%–8% and increased individual muscle fibers by 12%. No overall changes in these variables occurred in the conventional only high-load group.

By contrast, the conventional training group statistically increased their 1RM (4%), vs (3%) with BFR.

👉BFR-Training Adaptations in Endurance-Trained Athletes:

Held et al (2020) showed surprisingly, huge effects after 3 weekly x 5 weeks in well-trained rowers: VO2max (9%) and maximum aerobic power output (15%) with BFR vs no change in the conventional training group.

📍2.
👉Muscle Strength and Structural Adaptations:

Grønfeldt et al. (2020) conducted a meta-analysis indicating that low-load BFR increases muscle strength (grouped across 1RM, isometric, and isokinetic tests) similar to high-load in untrained and recreationally active individuals.

Though, Lixandrãoe et al (2018) find that improvements in strength (grouped across 1RM, isometric, and isokinetic tests) were higher with conventional high-load Training.

Muscle Redox and Ionic Buffering:
Stay tuned for more on repeated sprints and running performance among other stuff!

Source

Primary source:
Pignanelli et al. (2021) Blood flow restriction training and the high-performance athlete science to application.

Original papers:
Bjørnsen et al. (2019) Type 1 Muscle Fiber Hypertrophy after Blood Flow–restricted Training in Powerlifters.
Held et al. (2019) Low intensity rowing with blood flow restriction over 5 weeks increases VO2max in elite rowers: A randomized controlled trial.
Grønfeldt et al. (2020) Effect of blood-flow restricted vs heavy-load strength training on muscle strength: systematic review and meta-analysis.
Lixandrão et al. (2018) Magnitude of muscle strength and mass adaptations between high-load resistance training versus low-load resistance training associated with blood-flow restriction: A systematic review and meta-analysis.

This clinically relevant research question has been investigated by Zanardini et al. (2020).

– FYI, considering the cold spring in Denmark, remember to dress accordingly..🥶

Background: High-load resistance training is recommended to improve muscle mass and strength, but BFR seems to provide similar adaptations.

Purpose – the effects of BFR Training for grip strength & hypertrophy.

Hypothesis: The effect of low-moderate load BFR Training in Maximum Hand Grip Strength (MHGS) and muscular size is similar to Conventional high-load training!?

Methods: 28 women, age 18-25, randomly assigned into two groups: BFR vs Conventional resistance training (No-BFR).

Outcomes – Muscle size measures & MHGS

Intervention – 3/weekly – 4xweeks as dynamic concentric contraction exercises on a dynamometer.

Intensity for the BFR group. MHGS at 30-35% 1RM in the 1. week, 40-45% 1RM in the 2. week and 50-55% 1RM in 3.-4. weeks.

Intensity for the No-BFR group. MHGS at 65-70% 1RM in the 1. week, 70-75% 1RM in the 2. week and 80-85% 1RM in 3.-4. weeks.

3 sets of 15-25 reps were performed until failure with 30 s. inter-set rest for the BFR group and 3 sets of 8-12 reps with 1 min. rest for No-BFR group.

Results – values presented as medians:

% Change in Right MHGS, BFR group vs No-BFR group: (5% vs 5.1%)

% Change in Left MHGS, BFR group vs No-BFR group: (8.7% vs 14.9%)

Arm Muscle Circumference, BFR group vs No-BFR group: (2% vs -0.1%)

Upper Arm Circumference, BFR group vs No-BFR group: (1.8% vs -0.3%)

Lower Arm Circumference, BFR group vs No-BFR group: (0.2% vs 1.5%)

Conclusion:

Despite the authors praising BFR training in their discussion, the results seems to be in line with comparable studies showing similar effects of Conventional high-load training vs low-load BFR Training.

Clinical Take – Thus, we recommend low-moderate load BFR for improving grip strength as an alternative or adjunct to high-load training. Hand therapists can utilize BFR training when the aim of the intervention is to increase muscle strength when high-load resistance training is contraindicated. E.g. this can be relevant for people who experience aggravation associated with conventional resistance training particularly for people suffering from hand osteo arthritis or hand rheumatoid arthritis.

Source:
Zanardini et al (2020) Effects of blood flow restriction training on handgrip strength and muscular volume of young women.

Additional source for BFR and grip strength: Credeur et al. (2010) Effects of handgrip training with venous restriction on brachial artery vasodilation.
Velic & Hornswill (2014) KAATSU Training and Handgrip Strength.

In a recent short article at Dansk Sports Medicine a group of researchers elaborate on their concurrent RCT that explores whether Low-load Blood Flow Restriction (BFR) Training is effective in the treatment for patellar tendon related pains.

Currently, at the Department of Sports Medicine at Bispebjerg hospital Denmark, the researchers are exploring the potential benefit of BFR Training in the rehab for tendon related overuse injuries e.g., tendinopathy vs conventional training.

So far, the body of literature appears with contradictory outcomes for the effect of Low-load BFR training vs Conventional high-load training in the treatment for pain and objective parameters of tendon health whether.

That is why this concurrent RCT is an important contribution to this less explored field BFR research and is pertinent before a general recommendation of low-load BFR should be prescribed as a first line rehab modality for tendon related pains and tendinopathy.

Introduction:

Eccentric and Heavy Slow Resistance (HSR) Training, particularly the later, is currently the recommended rehab modality for tendinopathy.

However, exercise modality and type of muscle work does not appear to be decisive, instead the total training volume and time under tension seem to be of importance. And notably, only about 25% experience relevant effects of HSR, after 12 weeks of progressive exercise.

The rational for BFR is inherently the low-load and fatiguing stimuli, with less strain on the joint and tendons, whereby modulation of the damaged tissue may be augmented compared to conventional training.

As presented in a previous post, this case-series from the corresponding group of researchers tested a 3-week training intervention in which they performed 3/weekly low-load BFR as 30% of 1-RM.

6/7 subjects experienced a clinically significant pain reduction (≥50%) measured in with a single-leg decline squat.

+4% quadriceps maximal isometric contraction strength.

-31% Doppler activity in the patellar tendon as an expression of reduced vascularization, which could indicate healing of the tendon tissue.

Preliminary conclusion from the authors:

Because of the methodological shortcomings, as the lack of a control group (not RCT) and few participants, the results need to be interpreted cautiously. But it seems that BFR may be effective in the treatment of tendinopathy!?

As explained, the current evidence is sparse with contradictory results for the effect of Low-load BFR training vs Conventional High-load training in the treatment and objective parameters of tendon health and importantly, considering the relative low success rate with the current recommended HSR Training. That is why, this RCT is an important contribution to the literature and we find it pertinent before a general recommendation of low-load BFR should be prescribed as a first line rehab modality for tendon related pains and tendinopathy.
So, stay tuned for the results of this RCT.

But wait – what is the rational for BFR in this population, if volume and time under tension is thought to be the decisive factors? And why should low-load No-BFR with inherently higher volume not be a better option!? . Any explanations of this opposition?

Primary Source: https://dansksportsmedicin.dk/ front page.. With Google translate as Your companion..

Selection of original articles:
Aagaard et al. (2020) The effect of low-load resistance training with blood flow restriction on chronic patellar tendinopathy – a case series.
Sata (2005). Kaatsu Training for patella tendinitis patient.
Centner et al. (20219) Low-load blood flow restriction training induces similar morphological and mechanical Achilles tendon adaptations compared to high-load resistance training.
Kubo et al. (2006) Effects of low-load resistance training with vascular occlusion on the mechanical properties of muscle and tendon.
Reeves et al. (2006) Comparison of hormone responses following light resistance exercise with partial vascular occlusion and moderately difficult resistance exercise without occlusion.
Makris et al. (2014) Developing functional musculoskeletal tissues through hypoxia and lysyl oxidase-induced collagen cross-linking.
Xia et al. (2006) Nitric oxide enhances collagen synthesis in cultured human tendon cells.

Thus, as a follow up on the previous post on the pros and cons for curved vs straight cuffs relative to thigh shape, we have the Leg Cuffs V3 in action. It shows how the rather simplistic designed cuff can be used regardless of thigh circumference.

So, if any one doubted the “one size fits all” label for the Leg Cuffs V3 Quadzilla here definitely proves them wrong.

Thanks to @curtis_demont for the original video material!
Walking Lunges + Quadzilla roar
T-bar Front Squat
Barbel Front Squat
Leg Extension

Nuff said, go hit the Gym with BFR for those quad gains whenever possible!

Thighs comes in various sizes and shapes. Though, most are conically i.e., tapered, particularly in muscular or plumper individuals which would best match the cone shape of the Leg Cuff V3. On the other hand, slender – less muscular or longer thighs would also have a decent fit with the V2’s.

The V3 can be adjusted to the shape of the limb by an arc-shaped design that, when attached correctly allows for a customizable fit by a an adjustable smaller diameter distally compared to proximally.

This design simply allows the user to adapt the shape of the cuff to a wider range of thigh shapes:

The narrowing triangle velcro-strap allows the proximal and distal circumferences to be adjusted, allowing the cuff to conform to a variety of cones, to accommodate different thigh shapes, as shown in the figure above (2. image).

You can test the fit during attachment before inflation by placing 4 fingers between the cuff and the thigh distally and proximally, aiming for similar tightness.

Final Considerations.

The Leg Cuff V3 is a state-of-the-art designed variable-contour cuff developed to better match different thigh shapes, and thereby provide more efficient pressure distribution, which enables less pressures to be used.

V3 is a single bladder cuff designed to safely restrict blood flow as either full occlusion i.e., 100% Limb Occlusion Pressure (LOP) or to decrease blood flow (40-90% LOP) by applying evenly distributed circumferential pressure around the thigh.

The internal stiffener helps direct the pressure exerted by the bladder inward towards the thigh, and helps maintain the cuff in a stable position during exercise. The nylon stabilizer is used during cuff attachment and helps prevent the cuff from shifting on the thigh during exercise.

As a rule of thumb, the V2 is designed to fit optimally on cylindrically aka. straight thighs. V3 which is contoured in order to form a cone during attachment, would probably be a better fit for approximately >70% of people. And remember, both Cuffs are applicable for thigh sizes 45->85 cm.

Source:
various articles at https://tourniquets.org/tourniquet-cuff-technology/

Background:
Blood flow restriction (BFR) training with low-load has shown to induce similar physiological changes to high-load with the benefit of less tissue stress. For comparison of Low-load training protocols, BFR reduces the workload (number of repetitions) needed to reach the point of fatigue compared with similar training without BFR.

In this study the authors compared One extremity low-load BFR vs No-BFR low-load (control group) on strength and hypertrophy for muscle groups proximal, distal, and contralateral to the cuff.

Methods:
A prospective, RCT, as healthy subjects were randomized into a 6-week low-weight training program with or without BFR on 1 Arm. Outcome measures included limb circumference and strength, between BFR-arm vs No-BFR-arm, BFR group vs control group, and No-BFR-arm vs control group.

Results:
A total of 24 subjects (14 BFR and 10 control subjects) completed the training intervention.

Significantly greater gains were observed in dynamometric strength for proximal musculature in the BFR-arm group:

Shoulder scaption, 30%

Shoulder flexion, 23%

Shoulder abduction, 22%

And distal musculature: grip strength, 13%

Vs both the No-BFR-arm and the control group (P <.05).

Arm and forearm circumferences significantly increased in the BFR-arm vs No-BFR-arm and control group (P = .01).

The non-BFR-arm group demonstrated greater grip strength vs control group (9%, P < .01). No adverse events were reported.

Conclusion:
Low-load BFR training provided a greater increase in strength and hypertrophy in the upper-extremity proximal and distal muscle groups relative to the cuff vs No BFR Low-load training.

As The non-BFR-arm showed a significant increase in grip strength compared vs control group, indicating a potential systemic effect.

Low-load BFR training could significantly benefit patients who are unable to lift heavy with conservative managed conditions such as osteoarthritis, Subacromial impingement syndrome (SIS), muscle strain, and tendinopathy.

Likewise, BFR can probably accelerate return to preoperative strength levels in rotator cuff repairs, labral repairs, shoulder and elbow arthroplasty, and upper-extremity traumatic injuries.

Source:
Bowman et al. (2020) Upper-extremity blood flow restriction- the proximal, distal, and contralateral effects- a randomized controlled trial.

In a recent meta-analysis by Cuyul-Vasquez et al (1), the authors discovered that only low-quality evidence can be identified for Low-load BFR training on pain and function when compared to Conventional resistance exercise. Though, in a response to this meta-analysis as a “Letter to the Editor” Cerqueira et Vieira (2) acknowledge the current lacking evidence, however, the authors would like to contribute to the discussion on the possible benefits of Low-load BFR training for the treatment of general knee pain.

The disputed statements & analysis from the original meta-analysis:

In the original paper the authors compared BFR exercise at 30% of 1RM vs Conventional high-load (70% 1RM) and low-load (30% 1RM) exercise.

Considering, the reported different results when Low-load BFR is compared to Conventional high-load vs low-load exercise, it is reasonable to consider that pooling the results from two distinct exercise intensities may have affected the results. A relevant shortcoming in the original RCT’s, is the fact that few studies match the exercise volume. As you will often find the BFR group has higher exercise volume as defined as load x reps x sets.

From the results in several original RCT’s and other reviews, it seems apparent that Low-load BFR is superior in regards to strength vs conventional Low-load exercise when the reps and volume are matched.

It is also well established that load-low BFR have similar but maybe slightly less effects on strength when compared to conventional high-load exercise.

Conversely, it can be proposed that for individuals who struggles with high load exercises due to aggravation of joint pain, that low-load BFR exercise can outperform conventional high-load training. This hypothesis is both in regards to worsening of joint pain but probably also in terms of strength as pain and not perceived effort can be the limiting factor for this subgroup.

This notion is consistent with Giles et al. (3), as they identified that for subgroups with higher levels of patellofemoral pain had additional strength gain with low-load BFR vs High-load training.

Subsequently, the drop-out rate for such subgroups is considered to be higher, which can be difficult to adjust for during data analysis.

Considering all of this, it seems appropriate to conduct both stratified and subgroup analysis as main outcomes for future RCT’s and if applicable for reviews as well:

1. Comparing functional, strength and pain levels, for individuals who experience pain aggravation associated with High-load training vs Low-load BFR

2. Load-low BFR vs Conventional Low-load training.

3. Load-low BFR vs Conventional High-load training.

Considering the current evidence, we find it reasonable to recommend low-load BFR training in clinical practice for people with knee pain, who currently or previously has experienced that conventional high-load training is an aggravating modality. But more research for low-load BFR for knee pain is still highly pertinent.

Source:

1.Cuyul-Vasquez et al. (2020) The addition of blood flow restriction to resistance exercise in individuals with knee pain- a systematic review and meta-analysis.

2. Cerqueira et Vieira (2020) Letter to the Editor about the article – The addition of blood flow restriction to resistance exercise in individuals with knee pain- a systematic review and meta-analysis.

3. Giles et al. (2017) Quadriceps strengthening with and without blood flow restriction in the treatment of PFP.

As described in a previous post the new optional direct attachment has some obvious advantages which are displayed in the video.

In the text below you will find some of the relevant considerations of Blood Flow Restriction (BFR) for the endurance-trained athlete. The focal strategies are deprived from the recently published paper by Ferguson et al. (2021).

Key Concepts:

BFR can possibly amplify the adaptive response to training and improve endurance performance in highly-trained individuals, by stimulus for angiogenesis (capillary supply) and mitochondrial biogenesis (more power inside the cell).

Future studies must clarify how BFR is best incorporated for highly-trained endurance athletes as a part of a structured programme!?

Introduction

The main objective for endurance athletes is to optimize the underlying physiological determinants of performance. BFR is one of many strategies to amplify the exercise-induced stressors and subsequent molecular signaling responses to enhance performance.

Many factors must be considered when programming in highly-trained individuals, defined as VO2-max > 65 ml/min/kg.

It is well known that the repeated bout effect is progressively attenuated as training is continued after a few months. It also seems that isolated increase in training volume is deficient to improve endurance performance, being particularly important to avoid “overtraining” or injury.

Key factors for improved endurance performance in the well-trained individual – how to educed plasticity of trained skeletal muscle.

Metabolic stress i.e., hypoxia – oxidative stress, skeletal muscle oxygenation, reactive oxygen species and the shear stress of reperfusion (blood returning to the working muscles)  capillary growth, mitochondrial biogenesis

BFR exercise presents an intensified training stimulus, due to distorted level of blood perfusion and oxygenation that gives rise to shear, hypoxic, metabolic, and oxidative stress signals beyond that of conventional training.

By use of BFR multiple variables can be manipulated, which has a significant impact on the level of physiological responses to exercise:

Continuous vs intermittent restriction and the timing of cuff application in relation to exercise.

As a rule of thumb, low-moderate intensity – continues pressure and very high intensity interval training – deflated prior to sprint.

It seems that absolute cuff pressures (mmHg) have a particularly significant impact on capillary growth and mitochondrial biogenesis.

Conclusion

BFR has the potential to induce enhanced physiological adaptations, including increases in capillary supply and mitochondrial function, which can contribute to improving endurance-exercise performance in highly trained individuals.

To be explored in future research:

Due to the variability in BFR research, no consensus of the optimal BFR program can be established as well as how to optimize BFR applications in a structured training programme needs further exploration!?

Source:

Ferguson et al. (2021) Blood-Flow-Restricted Exercise- Strategies for Enhancing Muscle Adaptation and Performance in the Endurance-Trained Athlete.

Currently 7 weeks after an Anterior Cruciate Ligament Reconstruction (ACL-R) and Sutured Meniscus.

By applying a step platform under the feed, range of motion of the knee can be increased and thereby shifting the muscle work from a primary glute-based exercise into a more hamstring dominant movement pattern.

This biomechanical consideration seems of importance in ACL rehab:

As the hamstrings posterior aspect inserts on the tibia (shin bone) and fibular head, the hamstrings can impart the posterior draw force on the knee. For this reason, the hamstrings are commonly referred to as ACL agonists as it co-contracts with the quadriceps during knee extension e.g. squatting to reduce anterior tibial translation.

Because the hamstring generates considerable antagonistic force, the hamstrings emerge as the principal structure contributing to reduce knee joint laxity after ACL-Reconstruction.

So, by specific hamstrings strength and endurance training you can assist the neuromuscular control of the knee as a likely protective mechanism by functional decreasing the demand for passive-mechanical joint stability.

In the second part of the video we got some body weight squats. This has been applied and progressed cautiously so far, because of the sutured meniscus and its inherently limited healing properties.

As a rule of thumb, when the meniscus has been sutured or resected, it is recommended to have a rather delayed implementation of bodyweight exercises considering the considerable risk of long-term osteoarthritis.

In the last part of the video, you will find the trick to completely deflate the cuff before detachment, which is important for the consecutive training session.

Source:

Bryant et al. (2008) Dynamic Restraint Capacity of the Hamstring Muscles Has Important Functional Implications After Anterior Cruciate Ligament Injury and Anterior Cruciate Ligament Reconstruction.

Please mind that the images above contain explicit footage of a dislocated ankle fracture not from the present study.

3 semester students conducted a project in collaboration with Peter Larsen and Rasmus Elsøe at Aalborg University Hospital.

The aim this feasibility study was to explore if low-load BFR Training can help patients who suffer a major bone fracture regain their function faster.

People with major lower limb fractures often have to immobilize the injured leg in a cast for several weeks or months without being able to do specific resistance exercise for the particular limb.

Therefore, many people lose muscle mass, which leads to loss of function, reduced joint stability and strength as well as pain, explains chief physician Rasmus Elsøe from the Department of Orthopedic Surgery.

The specialized training is called “occlusion training” aka BFR Training which is low-load resistance training combined with partial restriction of the blood supply to the working muscles.

In healthy people, this training seems to increase muscle mass and muscle strength about as much as conventional resistance training, but with less impact on bones and joints – so, we hope that this also applies to patients with bone fractures, says physiotherapist Peter Larsen from the Department of Physiotherapy and Occupational Therapy.

Exactly this form of training is interesting to take a closer look at, as it potentially provides the opportunity to initiate rehab sooner compared to standard care, thereby attenuate the loss of muscle mass and strength and reduce functional deficits. Their semester project showed promising results and for the majority of patients, this new form of training was a positive experience.

This study provides exciting new perspectives for future studies that can explore whether this new form of exercise can get our patients back to full function faster after bone fractures.

Stay tuned for a follow-up study comparing the functional effect of early BFR intervention in fracture rehab.

This is the 3. post, in the continuing series on BFR augmented rehab for ACL-R and sutured meniscus, currently 6 weeks post op.

In the video you will find that the exercise selection has been progressed by single leg press and end-range isotonic knee extension. Additionally, we’re utilizing contralateral high load resistance training for the inter-set rest periods.

The primary concern for the leg press is the compressive force within the knee, possibly affecting the sutured meniscus. Though, as the meniscus has a rich supply of pain receptors, monitoring any aggravation is most likely sufficient for monitorization of progression e.g., load and ROM.

In the 2. part of the video knee extension has been progressed from end range isometric contraction to limited-range isotonic contraction.

It is commonly described that Open-Kinetic-Chain (OKC) exercises like knee extension creates detrimental anterior forces within the knee.

For this reason many recommend to avoid OKC after ACL-R because of the proposed strain on the graft increasing knee laxity.

Though, when examining the vast amount of research, it seems less of importance beyond 4 weeks post op. On the other hand, it seems appropriate to limit ROM from 90-40° when using moderate or high relative load for OKC exercises at 4-12 weeks post ACL-R.

Secondly, considering the tensile force from the anterior glide of the shin bone relative to femur, it is recommended to place the shin pad more proximally. With the pad positioned mid-shin vs ankle level, the strain on the ACL is approximately 50% less.

But utilizing low-load we can probably exercise the joint in full ROM with less of a concern in regards to graft stress. And by augmenting this low-load condition by BFR we can amplify the muscular recruitment similarly to a high-load condition.

Apparently, BFR can be such a game changer especially for the early-mid phase rehab in ACL-R.

Any thoughts on this exercise prescription or concerns for laxity?

Primary Source:

Perriman et al. (2018) The Effect of Open- Versus Closed-Kinetic-Chain Exercises on Anterior Tibial Laxity, Strength, and Function Following Anterior Cruciate Ligament Reconstruction: A Systematic Review and Meta-analysis.

This time around we have a guide for measurement of lower body LOP, as this can be a bit more tricky compared to upper body assessments.

So, if you’re having problems with lower body LOP assessments, please see the following troubleshooting guide:

✔Make sure that the cuff is completely deflated before attachment on the most proximal part of the thigh.

✔Also mind that you got a tight fit before inflation (pumping up) and please remember to not sit directly on the cuff.

✔Position yourself or your client as displayed above resting the foot on the floor with a slight bend in the knee.

✔Connect the Bluetooth Device directly into the cuff or to the new “Wireless” edition of the pressure gauge as displayed.

If you receive an error message on the app display, then you should manually control the deflation speed as shown in this video:

✔Keep inflating to about 280 mmHg, before you let the Bluetooth Device deflate the Cuff.

✔Turn the screw-cock on the Fit Manometer (pressure gauge) to slightly speed up deflation as shown.

✔The green graph very peaks is only allowed outside the white window for a successful measurement.

✔If this seems troublesome, try to deflate the cuff with the push-button, thus keeping a slightly accelerated deflation speed through the cock-screw and try again..

✔Please mind that even the slightest movement interferes with the measurement and can make it impossible to measure LOP.

✔Please be patient as it can take some time to get it just right – practice makes perfect!

LOP will drop slightly if you do consecutive measurements and there may be a variance of 5-15% of SYS/LOP relative to body positioning, e.g. seated vs. lying.

230 mmHg SYS(LOP) is the maximum measurable pressure, so if you have excessively large thighs it might not be possible to measure.

We recommend the prescription of relative pressure i.e. 40-80% of LOP measured by the Bluetooth Device, Handheld dopplers or the “Calculate Pressure” module at training.fitcuffs.com.

Relevant Source:

El-Zein (2020) (Thesis) the use of a portable Bluetooth Device to measure blood flow restriction training pressure requirements: a validation study.

Berger et al. (2001) How Does It Work? – Oscillatory blood pressure monitoring devices.

Babbs (2012) Oscillometric measurement of systolic and diastolic blood pressures validated in a physiologic mathematical model.

Jordanow et al. (2018) Comparison of oscillometric, Doppler and invasive blood pressure measurement in anesthetized goat.

Limb Occlusion Pressure or LOP is the minimum pressure needed to fully block both arterial & venous blood flow. In display 160 mmHg is LOP for this particular person, for that limb, in this position with this exact cuff (Arm Cuff V3).

When preparing for BFR training just set the pressure relative to 100% LOP, but without the Bluetooth Device attached, as this will automatically deflate the cuff.

We recommend to measure LOP in a seated position with the following recommendations for setting the pressure during upper body exercise:

Lying exercise: 40-70% of LOP & seated or standing exercise: 40-80% of LOP. For swift conversions of % to mmHg by our app check the LOP module at training.fitcuffs.com.

“Based on the results of our study, we recommend using the Fit Cuffs® portable Bluetooth Device for objective and personalized BFR practice. This device is a valid, reliable and low-cost replacement for other measurement devices, which are substantially more expensive and require considerable usage skills. Thus, using the Bluetooth Device would offer BFR practitioners the ability to provide high-quality services for their clients or patients, ensuring minimal risks and optimal results regardless of location.” El-Zein (2020).

Nerd Alert – The Bluetooth Device works by oscillometrics i.e, analyzing pulse waves and the absence of pulse waves. This is fundamentally the same as ultra sound by handheld dopplers that detects the absence of blood flow.

– The correct terminology is probably “Arterial Occlusion Pressure” (AOP), but LOP and AOP can for practical applications and explanations be used interchangeably. Total Limb Occlusion (TOP) is another term used in BFR research, this method resolves the problem with hemodynamics i.e., blood pressure variability in relation to external stimuli. So please mind, when doing repeated and continues measurements of LOP on the same limb, readings will vary because of the hemodynamic response to BFR.

Source:

El-Zein (2020) (Thesis) the use of a portable Bluetooth Device to measure blood flow restriction training pressure requirements: a validation study.

Morais et al. (2016) Upper limbs total occlusion pressure assessment; Doppler ultrasound reproducibility and determination of predictive variables.

Loenneke et al. (2014) Blood flow restriction in the upper and lower limbs is predicted by limb circumference and systolic blood pressure.

Zachary et al. (2020) Limb Occlusion Pressure: A Method to Assess Changes in Systolic Blood Pressure.

Disclaimer: When assessing conventional blood pressure, you should always use a calibrated cuff, i.e., width of the cuff relative to the circumference of the limb you are assessing. That is why you can not use Fit Cuffs product selection to measure “blood pressure” and this combined unit is only valid for assessment of LOP.

As resting pain and swelling has continually subsided, this is less of a concern in this particular case. Like the recent post, the primary focus is to attain full i.e., symmetrical knee extension, currently missing about 3 degrees compared to the contralateral knee. Please consider that blood flow restriction (BFR) is only a small part of the exercise scheme, but nevertheless a clinically relevant add-on.

In the first half of the video BFR-cycling is in display, because this is a relevant avenue to attenuate strength and muscle loss, while improving cardio vascular fitness as a subsidiary concern at this early phase.

Though, as mentioned in the latest post, the client just recently progressed his knee flexion to the extent of pedaling not being an aggravator and thereby becoming an important part of his rehab scheme.

Very low intensity cycling, can help with general healing mechanics, but other important rehab parameters such as muscular- and cardio vascular fitness can normally not be improved at this stage. As pedaling places his knee near end range flexion, this bend position is preferable unloaded and BFR is particular of interest for this client. By keeping the bike unloaded we can protect the ACL graft and the sutured meniscus, and BFR is simply just amplifying this otherwise less effectful exercise prescription.

In the 2. part of this video you will find low-load BFR knee extensions progressing from the latest post with isometric resistance at terminal knee extension and slightly higher pressure (mmHg).

In the inter-set rest period we got contralateral high-load resistance training to regain muscle mass and strength by cortical, subcortical and spinal level transfer.

By combining both training modalities we’re attaining the potential benefit from both a neurological and a peripheral muscle perspective.

Source:

William et al. (2017) Blood Flow Restriction Training- Implementation into Clinical Practice.

Formiga et al. (2020) Effect of aerobic exercise training with and without blood flow restriction on aerobic capacity in healthy young adults: a systematic review with meta-analysis.

Slysz et al. (2015) The efficacy of blood flow restricted exercise: A systematic review & meta-analysis.

Carroll et al. (2006) Contralateral effects of unilateral strength training: evidence and possible mechanisms.

In the present post and the following, the focal point is how to add blood flow restriction (BFR) for ACL Reconstruction (ACL-R), so please consider that BFR is used in combination to the client-specific and standard care rehab exercises.

Currently, 4 weeks post op. the goal is reaching terminal knee extension asap and secondly, to attenuate muscle loss in the affected limb e.g. quadriceps, as joint effusion and swelling has almost abolished.

As the meniscus was repaired by sutures, limiting weight bearing activities and graduated exposure are imperative for the first weeks. Which is particularly important for his long-term knee mechanics, i.e., to evade knee OA.

In the video we got unloaded knee extension amplified by BFR, as the client is taxing to reach terminal knee extension.

For this client, the new direct connection Fit Manometer is a convenient alternative to the standard attach and detach solution and please notice this updated model is currently included in the Complete V3 versions. With this basic add-on, the pressure (mmHg) is swiftly monitored and adjusted accordingly by the rapid-deflate button or the screw-cock.

The sub-goal for this client is to succeed with the 30x15x15x15 rep protocol, then progressing the pressure to about 80% of Limb Occlusion Pressure (LOP), before using external load. Making sure no additional swelling or pain occurs compared to his conventional rehab exercises.

As a site note, knee flexion just progressed today and just barely enough to pedal on an exercise bike, so this will be implemented properly to his continued rehab.

More BFR applications will soon be implemented and likely also in conjunction with his recent and successful experience on an exercise bike.

Stay tuned to follow this rehab journey and hopefully a successful return-to-play within 2021.

Relevant source on the effect of BFR amplified rehab in ACL-R:

Hughes et al. (2018) Blood Flow Restriction Training in Rehabilitation Following Anterior Cruciate Ligament Reconstructive Surgery: A Review.

The “Fit Manometer Wireless” is available now at fitcuffs.com with a reduced introductory price via this link Fit Manometer Wireless.

This new featured model is durable and developed with the same type of connectors, so it can be used in conjunction with all of Fit Cuffs products and for all sort of passive modalities, resistance exercises and BFR-Cycling. One-Size-Fits-all.

We find this to be a convenient option in many situations for lower body exercise, as this optional wireless edition has some obvious assets:

✔Instant pressure assessments during inter-set rest periods.

✔Quick pressure adjustments during exercise.

✔Swift inter-set deflation and inflation of the cuffs.

✔Assessment of pressure fluctuations during exercise.

✔Rotating gauge for easy bilateral application.

We find this to be a convenient alternative for passive Blood Flow Restriction modalities such as Ischemic Precondition (IPC), post-exercise recovery or to apply during periods of immobilization to attenuate muscle loss.

Bilateral application is especially relevant for BFR-cycling. As this allows for convenient assessment of pressure without the need for re-attachment and detachment.

Relevant in clinical settings for people with contra indications and comorbidities as instant access to pressure can be preferable.

Maybe some obvious and relevant implications are missing, if so, please mail us at into@fitcuffs.com or if this new edition has any interest for you!?

INTRODUCTION The effects of treadmill running training performed with or without BFR / Occlusion Training on parameters of running performance.

METHOD 16 subjects assigned to BFR or CON for 8 sessions of training. Before and after the trial, subjects completed an incremental running test to determine:

Peak running velocity + maximal oxygen uptake + running economy. Followed by a time to exhaustion run performed at peak running velocity.

Training for both groups consisted of progressively increasing volumes of 30-seconds (reps) completed at 80% of peak running velocity, 2 times a week:

Repeated bouts (reps) of 30-s running interspersed with 30-s passive rest.

The initial training session consisted of 2 sets of 5 reps.

Between each set, rest for 150-s without BFR.

Thereafter the total volume of training was increased progressively by 2 min (equivalent to 2 reps per session until the final session of 3 sets of 8 reps.

RESULTS The BFR and CON groups reported gains (6.3±3.5 vs 4.0±3.3%) in VO2max following training with small differences between groups.

Similarly, peak running velocity and incremental test time increased in both training groups with a small additional enhancement in favour of the BFR group.

Running economy improved for BFR but not in CON. Time to exhaustion also increased for both (27±9% vs 17±6%) with a small favour of the BFR.

CONCLUSION Running with Blood Flow Restriction during high intensity sessions may provide additional beneficial adaptations, which may lead to practically gains related to running performance. These gains are predominately due to peripheral adaptations mostly occurring at the muscular level, possibly via an increase in muscle strength or an enhanced ability to resist fatigue inducing metabolites!?

What are you thoughts on these adaptations- Improved muscle strength or fatigue resistance?

Source: Paton et al. (2017) The effects of muscle blood flow restriction during running training on measures of aerobic capacity and run time to exhaustion.