Unstable Surface Training and Core Activation

The phenomenon of unstable surface and core training has grown exponentially over the years.

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Videos of individuals demonstrating feats of “balance and coordination” drills on Bosu balls alongside pointless plank variations have dominated the idea of core development. Unfortunately, not only are some of these variations outright dangerous, the majority are rather ineffective at producing performance gains.


The rationale behind unstable surface training has never been clear likely due to the lack of scientific literature supporting it. Some individuals propose that it induces superior core activation against basic exercises used for decades.

Additionally, many individuals have been led to believe that in order to increase core strength, core specific exercises are necessary. This couldn’t be further from the truth, according to a 2008 study in the “Journal of Strength and Conditioning Research,” which examined plank variations and crunches against heavily loaded compound movements such as the squat and deadlift for activation of the core.

The study found the deadlift and squat to have two- to six-times greater core activation, respectively, than the plank and crunch variations. This and several other studies alike have demonstrated time and time again that the core is paramount in successful heavily loaded strength training movements, unparalleled by body weight “core specific” exercises.

Another study was conducted in 2010 by the “International Journal of Sports Physiology and Performance.” It examined activation of loaded squats on both stable and unstable surfaces. Not surprisingly, average activation of the stable environment was much greater than the unstable.

Unstable surfaces compromise force generating capacities, explaining why one cannot jump as high off of sand as they can on a firm surface. Additionally, unstable surfaces may increase the risk for injury, thus if increased athletic performance is desired one is better off to abstain from these variations.


One point that must noted regarding unstable surface training is its place in rehabilitation settings.

It has been well documented that individuals suffering from injury or recovering from surgery can benefit from unstable surface or balance training because it allows for a small stimulus and muscle co-contraction without having to necessarily load anything.

Physical therapists and athletic trainers alike have successfully used balance pads and similar unstable surface implements for years to rehab injured individuals. It must be understood that this training has its time and place but is not optimal when seeking maximum performance gains simply due to the fact that it can never be loaded to the degree of a stable surface.

In certain cases, excessive unstable surface training can even be detrimental to performance, as it requires a degree of muscle co-contraction, which is nonconducive the elastic stretch/flex paradigm of the stretch shortening cycle.

Above all, intelligent and informed exercise selection is the key to producing long lasting gain. Trends come and go, but the most effective methods for training shine through time after time.

Rate of Perceived Exertion for faster results

Within strength training, it is common practice to lift weights at a prescribed load based on one’s repetition maximum (1RM). This is highly effective, as loads directly correspond with the number of reps and sets, as well as the desired performance outcome. 

A common example for a trainee may be performing four sets of three reps at their 85% maximum load on the back squat. If their 1RM was 300 pounds, they would do four sets of three repetitions at 255 pounds. What this does is allow the trainee to work with loads that they know they can handle for a given number of reps, while developing a specific physiological quality.  

Again, while this is highly effective and convenient, it is only one way to train, and does carry its own cons. 

Mainly, it does not count for daily fluctuations in energy levels, gains in exercise proficiency, or strength over time. If one continuously uses 300 pounds as their known 1RM, they will perform every rep of subsequent sets off that number. Some days the trainee may be fatigued and unable to meet the proposed demands, while other days you may feel fresh and capable of more. Fortunately, there is another highly effective alternative. 


A different way

Another method to prescribing and performing training loads is through rate of perceived exertion via the CR-10 Borg Scale. The number 1 represents the lowest level of effort whereas 10 represents maximum effort. 

This method has been proven effective since its inception nearly 60 years ago as an alternative method to monitor and prescribe training loads through workouts. A study in the Journal of Strength and Conditioning Research titled “Monitoring Exercise Intensity During Resistance Training Using the Session RPE Scale” states that the use of an RPE scale prior to a workout allows confidence in exercise intensity without having to test as frequently. 

Essentially, the study concluded that RPE was as effective as training RM percentages when it came to exercise execution. Allowing one to choose a load that is attributed to RPE rather than an exact number derived from testing also appears to alleviate stressful situations where trainees are unsure if they can meet the numerical daily standard. 

Overall, this could equate to fewer injuries, lower levels of burnout, and greater trainee independence via autoregulation. 

It must not go without saying that loads and programs prescribed via 1RM are still highly effective. Often times I will use a blend of both methods when creating training programs, with the understanding that each method has its own time and place. 

That being said, for the novice trainee it would likely be beneficial to use the RPE scale through the first six months to a year of training as they may not know their 1RM on each lift or have any reason to test it yet. 

One should not completely abandon RM prescriptions, or 1RM testing for that manner as they are still highly valuable tools. Instead, two methods should be used synergistically and integrated into programming appropriately. 

Remember that training is a science, thus defined as “the intellectual and practical activity encompassing the systematic study of the structure and behavior of the physical and natural world through observation and experiment,” according to Merriam Webster. 

We can assume that different methods will vary in their effectiveness amongst populations and there is no one size fits all. Keep experimenting and seeking better ways to train.