The fitness industry never does things by halves, does it? Everything becomes black or white, and very few people pay attention to the shades of grey in between. Before the 90s, unstable surface training was used exclusively by physiotherapists and the occasional sports coach. Then it got picked up by personal trainers and really blossomed in the twelve years after the Millennium as it becomes part of the Functional Training movement.
At some point between 2008-2010 (give or take a couple of years), functional training and instability training became something that everyone was doing. People would look over at the weights area and scoff at all the “Bros” who were wasting their time training in single planes. Didn’t they know that the bench press was not a functional movement? Gyms became filled with people squatting on Bosu Balls, performing planks on suspension trainers, and lunging in every single direction possible.
Then, inevitably the backlash occurred. People decided that functional training and unstable surface training was a bad idea, that it had no benefit, and that anyone who used it was clearly an idiot. So which is it? Is functional training the incredible training tool that it was cracked up to be? Or is it a joke? The truth, as ever, is somewhere in the middle. In this article, we will discuss what functional training is, what benefits it offers, and when to avoid it.
What is Functional Training?
Functional training is a perfectly effective method of rehabilitating people who have been injured, or who have suffered from medical issues such as strokes. It is based on the idea that the movements that you perform should reflect the movements that you do in real life. This is mostly because the people recovering from injuries are either sedentary (recovering from car accidents or falls) or people who were injured performing specific sports.
If you got injured playing tennis, then it makes sense to use similar movements to tennis in your recovery. If someone never exercised before their injury it would make sense to rehabilitate them using everyday movements such as picking up a box or climbing stairs. There is nothing controversial about this, and it has been shown to be effective.
The problem came when people took functional training out of the physiotherapist’s office and brought it into the gym setting. In fact, even that’s not exactly where the problem occurred because when used correctly, functional training is perfectly acceptable in a gym setting. But it should not be seen as a replacement for resistance training, it should be seen as an accessory to resistance training.
Some trainers and fitness fanatics started to use functional training instead of resistance training, and would even vilify traditional strength training due to it being “non-functional”. The fitness industry does this all the time, by the way, every few years there is some brand new magic program that will replace good old strength and conditioning training. Bodyweight-only training, kettlebells, Insanity workouts, CrossFit etc. … But nothing ever does.
That’s because traditional strength and conditioning exercises are functional. Squatting is a common movement that is underused in Western society, but is used all the time in many cultures. Deadlifting is basically teaching you how to pick things up carefully. Pulling and pushing movements such as bench presses and pull-ups are also functional movements. CrossFit and kettlebell training were successful because they integrated well with strength and conditioning rather than being promoted as a replacement.
Examples of good functional training exercises would be lunges with twists, single leg barbell Romanian deadlifts, suitcase deadlifts, and the single arm Farmer’s Carry (a.k.a., suitcase carry). All of these exercises are slight variations on standard strength and conditioning exercises, but they add in an extra element such as the twist in the lunge, or the asymmetrical loading in the suitcase carry or Romanian deadlift (see above).
A single arm farmer’s carry perfectly recreates carrying a heavy suitcase while walking to work, it requires increased core stability as there is an uneven weight which can affect balance. It’s also a great exercise for grip strength, muscular endurance, posture, and abdominal strength. This is a perfect functional exercise but is also a great exercise for anything.
A suitcase deadlift is another good example of a functional exercise that is also a great exercise in its own right. It requires the same movement as a regular deadlift, but instead of picking up a weight that is in front of you and balanced across both sides of your body, you are picking up a weight that is on one side. This recreates picking something off the floor, making it functional, it helps improve balance, core stability, and also has the benefits of a regular deadlift (fat burning, muscle building, etc).
What is Unstable Surface Training?
Unstable surface training is a form of training that is under the umbrella of functional training, though there are many who say it should be separate. With unstable surface training, the exercise is the same as a normal strength and conditioning exercise (i.e. a bench press or squat) but the surface that you perform it on is altered. It is unstable.
Performing a squat on top of a Bosu ball is an example of unstable surface training, the squat is performed in the same way as a normal squat would be, but the surface you are standing on is unstable – this theoretically requires more muscle activation to help you perform the exercise and maintain your balance at the same time.
As with functional training, unstable surface training came out of physiotherapy labs and crossed into gyms. It appears to have certain very specific benefits, but is often overused and overvalued by gym goers. The old adage that there is no such thing as a bad exercise, just bad applications seems to apply here.
What Do Some Experts Say?
While many gym goers and personal trainers look upon unstable surface training as a complete joke, and others see it as the greatest training technique since someone invented the deadlift, the experts are more circumspect.
- Dean Somerset – “unstable surface training seems to provide massive benefits to lower leg injuries (shins, ankles, and feet) but beyond that, not much benefit for the lower body” 
- Eric Cressey – “unstable training is best used for upper body work, like sitting or lying on balls while training. For lower body work, keep your feet on solid ground” 
- Meghan Callaway – “If you are using unstable training methods, your body positioning, mechanics, and muscles used should look close to, if not identical, to the same exercise being performed on a stable surface, or with a stable object” 
- Tony Gentilcore – “There is some efficacy towards its use – and as noted it’s namely in the rehabilitative setting when we’re working with athletes or clients coming off an injury and we’re trying to re-establish proper motor patterns, work on muscle activation, or otherwise reintroduce (and progress) them to external loading” 
The consensus of these four experts is that unstable surface training does have a place in certain training programs – mostly rehabilitation programs. But there is little use for them outside of this. They also all agree that if you are going to perform these exercises you should ensure that your technique is as solid as if you were performing the exercise on a solid surface.
What Does the Science Say?
A 2013 study in the Journal of Strength & Conditioning Research compared a squat exercise performed on a stable and unstable surface . The study found that the more weight lifted, the more muscle fibers were recruited. This means that the surface that allows you to lift a heavier weight will recruit more muscle fibers. Obviously, this would be a stable surface.
What this study demonstrates is that in healthy volunteers, a stable surface that allows you to lift a heavier weight will recruit more muscle fibers (allowing greater strength and hypertrophy increases) than an unstable surface.
Another study in the Journal of Strength & Conditioning Research (2009) found that unstable surface training did not improve balance among people whose balance was not a problem . Meaning that people with balance issues may see an improvement, but people without should not waste their time.
We’ll look at one more study in the Journal of Strength & Conditioning Research, this time from Daniel Hubbard in 2010 . He sums unstable surface training (UST) up thusly:
“Although UST is an effective tool used to restore proprioceptive and reactive deficits in the rehabilitation of individuals with ankle and knee injuries, the effective application of UST to healthy adults appears to be very limited”.
The Last Word on Functional Training
As a personal trainer, or even if you are training yourself, the first thing that you should be concentrating on when designing a program is what the clients’ goals are. A leg extension exercise may not look like a functional exercise to most people, but if the client has a goal of building quadriceps size, then the leg extension is indeed functional.
Sometimes an exercise that may look crazy to outsiders can make perfect sense when you know enough about the client. There have been a number of times where people have looked on appalled as a large gentleman used the prone leg curl machine pad to strengthen their posterior neck muscles. Instructors will run over until the guy explains that he is a rugby player and needs to strengthen his neck to participate in the scrum.
A crazy looking exercise that would not be recommended for 90% of gym goers has a function for him. On the other side of the coin, you have exercises that are the polar opposite. Boring, one-dimensional exercises such as the leg extension (used properly this time) or the leg press. They may not appear functional, but for a new gym member or elderly person, a leg extension performed with perfect technique has a low learning curve and will be improving coordination, muscular strength, endurance, and will help them to progress to more complicated exercises in future. For that person, the leg extension is the most functional piece of equipment they could have.
The bottom line is that when it comes to exercise prescription we should completely clear our mind of preconceptions. Assess each exercise on its merits, and decide whether the exercise will help or hinder that specific client. Only teaching deadlifts, Olympic lifts, and the bench press may suit some of your clients, but it certainly won’t suit the majority of the population.
Saying that though, you should also assess each individual client on their abilities rather than your pre-conceptions of what they can achieve. You might find that your 70-year-old female client is a natural deadlifter, while your 20-year-old male client does not have the flexibility or coordination to venture away from the leg press just yet. Find what is functional for the client and build them towards future progression.