BFR & Safety Concerns
The eternal question is whether BFR is safe? The simple answer is Yes, particularly with Fit Cuffs®
We recommend using our algorithmic pressure at the Fit Cuffs Training App “Calculate Pressure” or a percentage (40-80%) of Limb Occlusion Pressure (LOP) which is a concept that quantifies the amount of blood flow that is restricted. LOP can be assessed by the Bluetooth Device, handheld dopplers, or by high-quality pulse oximeters.
The general recommendation is to avoid severe and unintended muscle damage for your first session of BFR.
As a rule of thumb, when unaccustomed to BFR in combination with low-load resistance training, avoid going to failure and use a preset protocol of about 30x15x15x15 reps, at about 20-30% 1RM, with 30-45 s. inter-set rest for one exercise. Though, gradual exposure to higher pressures (70-80% LOP) or load progression through the repeated bout effect is key for long-term adaptations to BFR Training.
Proper application of Fit Cuffs with precautions and relevant safety measures, is highly effective at augmenting the physiological adaptations to low-load resistance and aerobic training in all populations regardless of age or training status.
Absolute contraindications for BFR are rare, that is circumstances where one should not use BFR considering the current guidelines. In clinical practice, most contraindications are relative. That is why a thorough examination and anamneses to evaluate the accumulated frailty of a client is vital.
- That is why we advise you to consult with your physician before you start using Fit Cuffs if any of the following apply ⇩
- The specific cardiovascular responses to Blood Flow Restriction (BFR) Training ⇩
It is important to identify if the following are present in Your clients, as it will influence whether or not BFR is applicable.
- Severe chronic heart disease
- Untreated Type 1 or type 2 diabetes – BFR Training should not be used in patients with glucose > 250 mg/dl associated with diabetic retinopathy and diabetic ketoacidosis.
- Kidney disease
- Concurrent treatment for cancer, or you’ve recently completed cancer treatment
- Untreated high blood pressures >140/100
- Clotting problems or abnormal bleeding problems (coagulation disorders)
- Cardiac arrhythmias
- Damaged or chronic veins or arteries
- BMI> 35
- Open wounds or stitches in the areas of cuff attachment
- Severe rejuvenate in the legs
- Severe functional disorders
- Varicose veins are compromised vessels that suggest a weakened venous system
- Controlled high blood pressures
The amount of comorbidities someone has determines if BFR is contraindicated. But currently, no absolute recommendations can be made. So far, the clinician or physician must decide whether a client should or not do BFR.
The data from a survey (Nakajima, et al. 2016) from 2006 – 2016 in 12827 individuals at 232 different facilities, shows that the incidence of side effects or adverse events from BFR had about the same relative risk as conventional exercise.
Most importantly, thorough patient history and examination before use will help to identify absolute contraindications to BFR. These include a history of previous DVT, Stage III or greater hypertension, higher class arrhythmias, the early post-operative period from major surgery, and acute sickness or fever.
When conducting the exercise be aware of the following symptoms:
- Sensation of numbness
- Pins and needles
- Uncomfortable tingling
- Severe discomfort
- Lightheadedness or dizziness
- Subcutaneous hemorrhage
- Cool Feeling in the limbs
Hemodynamics (the study of blood flow,) after BFR have shown no evidence of increased risk of thrombosis, when studying possible contraindications.
The cuff should only be placed at the upper arm or upper thigh. We do not recommend placing the cuffs at the forearms or calf as the arteries and nerves are more superficial in these areas and can substantially increase the risk of adverse events.
As described, it is recommended to use a relative occlusion pressure at 40-80% of the individualized LOP / AOP and utilize the principles of graduated exposure to reduce the risks associated with BFR resistance- or Cardio Training.
Additionally, please also consider that higher relative occlusion pressures do not have any additional effect on the main muscular response. Though, be aware that untreated high blood pressure and the sensation of tingling can be a contraindication that the health care provider should pay special attention to.
During exercise, the central and peripheral cardiovascular systems respond to increased oxygen demand from the muscles.
The effect of BFR on the cardiovascular response relies on the restrictive pressure, training modality (resistance training vs aerobic training), mode of application (continuous or intermittent), and restrictive pressure time.
Previous studies that have used a continuous training protocol where the occlusion pressure is maintained during the interest rest periods and have mostly found increased Heart Rate (HR) and blood pressure (BT) compared to training without occlusion e.g., conventional resistance training. Even though, no higher minute volume during training occurs, because Stroke Volume (SV) decreases in proportion to the increase in HR.
In a review by Cristina-Oliveira et al. 2019, they found evidence for BFR Training increases BT beyond conventional training. Based on the studies examining peak BT values during training protocols, they estimated BFR Training to increase BT by 5-10 mmHg above the expected response to conventional training.
However, the literature is contradictory, as recent studies do not find the same increases in HR and BT, for training protocols with continuous pressure. This could potentially be due to the fact that recent studies use individual LOP to a greater extent as opposed to arbitrary non-individualized pressures used by many of the previous studies. Patterson et al. 2018 found in their study that only 11.5% of previous studies utilized individualized pressures ie, LOP.
Although several previous studies find increases in BT during BFR Training, it is important to emphasize this main finding. This is parallel with the potential risks associated with an acute increase in the cardiovascular response, BFR has been shown to reduce BT in the hours after training and chronically after weeks or months of training with BFR.
This acute vs chronic effect on the cardiovascular system has been explored in other forms of exercise like high-intensity interval training but has only recently been discovered in BFR Training.
From the existing literature, it can be summarized that higher occlusion pressures induce higher cardiovascular potential risks associated with BFR. People diagnosed with cardiovascular disease are prone to an excessive increase in the sympathetic nervous system during exercise, known as the exercise pressor reflex. Attention to this potential complication is warranted, however, this can be addressed by reducing the restrictive pressure, total restrictive time, utilizing intermittent pressure, and prominently by the principles of graduated exposure
Blood Flow Restriction – Risk Stratification
Risk stratification is a tool that allows clinicians to use their knowledge, skills, and expertise to assess and manage any risks of BFR. The following questionnaires for risk stratification are adapted to guide clinicians for the referral and assessment, when necessary.
- Thrombosis (DVT) – Risk Factor Assessment ⇩
- Diabetes Mellitus (DM) – Risk Factor Assessment ⇩
- Cardiovascular & Hypertensive – Risk Factor Assessment ⇩
- Rheumatoid Arthritis (RA) – Risk Factor Assessment ⇩
Using the IMPROVE risk assessment model, patients are classified into low-risk tier (0–1 points), moderate-risk tier (2– 3 points), and high-risk tier (>= 4 points)
In the presence of any of the following risk factors cited, the patient with DM is classified as high risk, precluding the use of BFRT without physician clearance
In the presence of any of the following risk factors cited in Table 5, the patient with hypertension is classified as high risk, precluding the use of BFRT without physician clearance
Risk stratification for RA patients should include screening for DVT risk as these patients are at an elevated risk of VTEs, pulmonary embolisms and DVT formation compared to the general population. In conjunction with DVT screening, in the presence of any of the following risk factors cited below without physician clearance, the patient with RA should avoid BFRT, and another modality should be used
- Patterson et al. (2019) Blood Flow Restriction Exercise, Considerations of Methodology Application, and Safety.
- Patterson & Brandner (2018) The role of blood flow restriction training for applied practitioners: A questionnaire-based survey.
- Wernbom et al. (2020) Commentary: Can Blood Flow Restricted Exercise Cause Muscle Damage? Commentary on Blood Flow Restriction Exercise: Considerations of Methodology, Application, and Safety.
- Burr et al. (2020) Response: Commentary: Can Blood Flow Restricted Exercise Cause Muscle Damage? Commentary on Blood Flow Restriction Exercise: Considerations of Methodology, Application, and Safety
- Yasuda et al. (2016) Use and safety of KAATSU training- Results of a national survey in 2016.
- Nakajima et al. (2006) Use and safety of KAATSU training: Results of a national survey.
- Nascimento et al. (2019) – Potential Implications of Blood Flow Restriction Exercise on Vascular Health.
- Christina-Oliveira et al. (2019) Clinical safety of blood flow-restricted training. A comprehensive review of altered muscle metaboreflex in cardiovascular disease during ischemic exercise.
- Wernbom et al. (2019) Risk of Muscle Damage With Blood Flow–Restricted Exercise Should Not Be Overlooked.
- Cezar et al. (2016) Effects of exercise training with blood flow restriction on blood pressure in medicated hypertensive patients.
- Heitkamp (2015) Training with blood flow restriction. Mechanisms, gain in strength and safety.
- Loenneke (2011) Potential safety issues with blood flow restriction training.
- Nakajima et al. (2011) Key considerations when conducting KAATSU training.
- Wernbom et al. (2011) Contractile function and sarcolemmal permeability after acute low-load resistance exercise with blood flow restriction.
- Loenneke et al. (2014) Does blood flow restriction result in skeletal muscle damage? A critical review of available evidence.
- Kacin et al. (2015) Safety Considerations With Blood Flow Restricted Resistance Training.
- Bond et al. 2019 – Blood Flow Restriction Resistance Exercise as a Rehabilitation Modality Following Orthopaedic Surgery: A Review of Venous Thromboembolism Risk
- Kambic et al. (2022) Is blood flow restriction resistance training the missing piece in cardiac rehabilitation of frail patients?
- Nascimento et al. (2022) A Useful Blood Flow Restriction Training Risk Stratification for Exercise and Rehabilitation