Blood flow restriction with high load resistance training for athletic performance

Training athletes who have a high training age in sports that require high levels of strength, speed and power can present unique challenges. Their ability to improve strength levels significantly diminishes as they accumulate years of training and competition in sports like track and field, rugby league, rugby union and Australian Rules Football. Whether this is due to their already high levels of strength, long term injuries, or they no longer have the ability to train at high intensities in the gym, strength & conditioning coaches still need to find solutions to maximise their sporting performance.

In addition to delivering sound strength programs based upon core fundamentals and programming principles, we must explore additional training tools that can provide such outcomes. Blood flow restriction (BFR) is emerging as an effective stimulus for these athletes.

BFR is gaining popularity in both the general and athletic populations because it can increase muscle strength and hypertrophy using loads as low as 20–30% of 1RM. This makes it look like the perfect training tool for musculoskeletal rehabilitation, and for older populations to assist with age related musculoskeletal issues, such as sarcopenia ^[1-4].

What is blood flow restriction training?

BFR training uses a special cuff to apply additional pressure to the most proximal region of the arms or legs during exercise. The cuff partially restricts arterial inflow and venous outflow in the working musculature, increasing the concentration of metabolites ^[6-8]. The metabolic stress of the increased metabolite concentrations may be a potent stimulus for the cascading effects that assist in the adaptive responses in the muscle. Some of the proposed mechanisms include an increase in acute anabolic hormone concentrations, stimulation of intramuscular signalling (independent of hormones and growth factors), intracellular swelling, increased type II muscle fibre recruitment, and stimulation of muscle protein synthesis ^[6,7]. Some exceptional reviews provide a more detailed understanding of these mechanisms ^[6,9].

In research, the most common loading for BFR corresponds to 20–30% of 1RM, with the primary outcomes being improvements in both strength and muscle hypertrophy. These are surprising considering that traditional (non-BFR) strength training requires loads of at least 60% of 1RM to stimulate muscle hypertrophy and loads over 80% of 1RM to stimulate strength gains ^[10,11].

For people who are injured, are pre- / post-operative or have compromised joints, low load BFR resistance exercise can effectively improve muscle strength and hypertrophy while decreasing joint articular and ligament stress. This has positive implications for those who need to improve muscle strength and hypertrophy but are unable to tolerate high loads.

There are also other well-documented yet underutilised advantages to BFR, including decreased joint and tendon pain ^[12,13], improveding markers of bone formation and contralateral strength effects ^[14,15].

Given this research, BFR is ready for sports performance practitioners to dive into possibilities for the strength / speed / power athlete who is trying to improve muscular strength, hypertrophy and power to transfer to athletic performance.

BFR or traditional resistance loading: Why not both?

Knowing the advantages of BFR and high load strength training, what about combining them?  

Traditional strength training relies on high levels of mechanical stress (i.e., load) on the body to activate the necessary pathway responses and mechanisms that result in observable physical and performance improvements. BFR, on the other hand, uses metabolic stress with low loads to elicit similar responses. Therefore, adding BFR to higher loading percentages seems a logical opportunity to amplify or maximise muscle activation, acute anabolic hormone concentrations and muscle cell signalling, creating a more effective stimulus via restrictive cuffs.

Moreover, if we consider strength training stress as the addition of mechanical and metabolic stress, BFR could afford the athlete a slight reduction in the high load mechanical stress (i.e., % RM) through the compensatory addition of metabolic stress.

Safety considerations: Buyer beware, and be informed

Two of the big questions I regularly get asked about BFR training are whether it is safe, and what evidence is available to support these claims.

A lot of the current safety concerns arise from the number of different BFR products available, which lead to users implementing protocols with varied levels of control and standardisation ^[31].

Products vary from low cost tourniquet straps through automated pneumatic inflation systems. With BFR training, the pressure should be consistent around the limb where the athlete has the cuff. This requires a cuff that is sufficiently well designed and well made to apply the same pressure around its entire circumference. Low cost BFR straps don’t regulate blood flow evenly due to how they tighten on the limb.

The inflation pressure of the BFR cuff is another important safety consideration, and should be individualized down to the level of the circumference of the user’s limb.

The initial step in calculating BFR pressure is to identify the lowest cuff pressure required to block arterial blood flow into the extremity distal to the cuff, otherwise known as limb occlusion pressure (LOP) or arterial occlusion pressure (AOP). A BFR pressure equivalent to 50-80% AOP / LOP is safe and effective ^[5].

Other basic safety rules for BFR training include:

• Avoid excessive limb occlusion or pressure
• Do not wear the bands directly on the skin
• Ensure the user breathes regularly when exercising
• Ensure correct placement of the cuffs: arms = upper arm, legs = upper third of quadricep
• Time of use in one continuous inflation cycle: 15 minutes for the arms and 20 minutes for legs
• Do not wear the bands on arms and legs at the same time

Overall, with respect to safety, in a controlled environment with trained and experienced personnel, BFR training appears to provide a safe alternative for most individuals, regardless of age or training status ^[59].

Take your time before introducing BFR to anyone. Do your due diligence, ensure it is right for the athlete you are working with and then gradually introduce it over a few weeks. This gives the athlete time to adjust to the new training stimulus and gives you time to adjust their BFR protocol, if required.

Applying broad findings to our unique populations

The second question wants to know about the evidence to support the BFR claims.

This can sometimes be a short sighted view if we are looking at methods to improve performance in elite athletes. I respect the need to gain a fundamental understanding of whatever concept we are trying to implement, BFR or otherwise. However, when working with athletes, we must remember that most studies include participants who are nowhere near the physical performance standard of the athletes that we work with. Additionally, the uniqueness of elite athletes requires a high level of individualisation, which academic studies rarely achieve and report.

Therefore, the existence of peer reviewed studies that include participants and protocols that are somewhat close to the athlete cohort that you work with is an important consideration when reading and transferring literature to the “real world.”

I have incorporated high load BFR lifting safely and effectively with the athletes I work with for over 10 years. When we look to literature, there is some very surprisingly supportive evidence for this under-utilised training method.

Studies investigating the acute effects of high load BFR strength training used loads of up to 70-90% 1RM for both the squat and bench press (Table 1). Wearing the BFR cuffs resulted in an increase in barbell velocity and power outputs of up to 20% compared against the no-BFR situation. Although these are acute studies, longitudinal training at improved barbell velocities can provide superior changes in performance parameters (e.g. 1RM, max speed, countermovement jump) than training with a slower barbell velocity. The addition of BFR cuffs can also enable athletes to perform more reps when performing a maximum repetition protocol. The athletes in these studies had good strength levels and experienced no negative issues with the addition of BFR.

Support for longitudinal high load BFR strength training is at the forefront of a study that examined the effects of three weeks of strength training at 70% of 1RM, where the athletes performed five sets of five repetitions of bench press, squat and pull-ups ^[25]. The BFR cuffs were on the thighs only and utilised an intermittent pressure protocol. The athletes wearing the BFR cuffs significant increased upper and lower body strength, sprint ability and power outputs compared to the control non-BFR training group. The BFR group also showed significant increases in testosterone concentrations.

The results demonstrate significant functional benefits of BFR training in an elite group of athletes with a strength training protocol that is reflective of an athletic population. Unfortunately, there remains a lack of longitudinal high load BFR strength studies, but the evidence holds promise for integrating BFR with high loads in strength training.

BFR with high load core lifts and ancillary exercises

The potential for BFR to acutely enhance barbell velocity in a longitudinal strength training program is motivating some of my current practice.

Working with a 40 year old ex-shot put and discus thrower, I initially measured the acute effects of high load BFR through strength testing. We first tested without BFR to ensure that fatigue would not skew any potential advantages to testing with BFR cuffs four days later. Adding BFR cuffs resulted in better barbell velocities for both the bench press and squat.

Looking at the longitudinal effects of a high load BFR strength program, I am using barbell velocity feedback and also incorporating cluster training for the high load exercises. Cluster training is a method in which a set of higher repetitions is broken down into smaller groups or clusters of repetitions where there is a brief rest period between intraset clusters. Compared to a traditional set and rep format, cluster training can increase force output and velocity and reduce fatigue within a set and across multiple sets ^[26,27].

Table 2 is an example of one of the sessions. The bench press and squat are the main high load exercises where we incorporate velocity feedback and cluster set periodisation. The loading for the squat is low (120kg) due to previous knee surgeries and the resultant inability to tolerate high loading.

After the squat and bench press are the ancillary exercises (3a-5b). For these, I don’t follow the typical 75 rep protocol for low load exercise. I prefer a more moderate high repetition scheme, in part because (a) I use a slightly higher loading than 20% 1RM, (b) the athlete will be completing several supersets and (c) he doesn’t enjoy very high repetition training.

For the warm up sets of bench press and squats, and for the ancillary exercises, the cuff pressure is continuous due to the lower loads and my goal of maximising the metabolic response from the BFR cuffs. We apply intermittent cuff pressure during the main high load sets, that is, we release the pressure per the protocols in the acute studies from Table 1.

This athlete has said that maintaining a continuous pressure for high loads is quite difficult, and would be a potential limiting factor for maintaining high barbell velocities. His current bench press 1RM is 150 kg; and, due to limitation in his knee, squat loads are limited to 120 kg. But he can still perform countermovement jumps and single leg isometric strength testing.

After four weeks of this training, we repeated the non-BFR testing and saw improvements for both the squat and bench press barbell velocities, as well as the vertical jump. Given his high training age, I suspect he’d experience bigger shifts in performance across an 8–12 week training period.

This athlete also said that the addition of BFR cuffs enables him to warm up and get into the session quicker than when training without them. He said the velocity feedback during the main “heavier” sets are a welcome addition, as it provides focus and motivation for each rep and set. And using BFR in the ancillary lifts enables a shorter session time, with two sets usually being sufficient. Perhaps another surprising comment is that he is not as sore the next day after this type of lifting, which is a nice change from the usual soreness associated with non-BFR high load lifting. On this point, Curty et al., ^[28] reported that adding BFR while lifting with supramaximal loads (130% 1RM) improved the recovery of muscle damage markers 24 hours quicker than without BFR cuffs.

Benefits of blood flow restriction: More than metabolites

Anyone looking to improve muscular strength and power can benefit from integrating blood flow restriction with their strength training. It’s still important to add load to the bar, but the amount of load that you have to add isn’t as much as during traditional, non-BFR strength training.

This has advantages across a myriad of scenarios that previously may have been challenging. For athletes with a younger training age, this can enable the S&C coach to focus on technical mastery while still seeing physical gains. On its own, this would be a positive motivating factor for young athletes: seeing the gains (visually and physically) without having to push for loads before they are ready.

BFR resistance training is also perfect for joint compromised athletes who struggle with high %1RM loading (>70% 1RM), yet still need to continue their physical development. In this scenario, BFR’s ability to decrease joint and tendon pain takes on extra salience.

During in-season competition phases, including short turnaround weeks, BFR could enable athletes to maintain adequate barbell loads and velocities with a decreased session volume.

Finally, BFR could be a great session for athletes who don’t enjoy the gym, where the use of velocity feedback for motivation and an overall shorter session may provide a welcome change in programming style.

Give your athletes time to get used to blood flow restriction. Spend a few weeks increasing the frequency and total time under BFR pressure. Use it initially in the warm up or with the ancillary exercises. When you are ready to incorporate it into the primary lifts, use it on the warm up sets first. Interestingly, by this stage a lot of athletes I work with enjoy the feeling that the BFR cuff gives and just continue using it with the main sets.

Velocity feedback is important, but it’s not a deal breaker if you don’t have access to it. The main consideration is the intent that the athlete gives in the concentric phase. Adding BFR to strength training programs has been a game changer in my practice. It doesn’t replace the fundaments and it never will, but when implemented correctly at the right time it does enhance the response and outcome. And for the athletes I work with, that is all that matters.