The practice gets its name from a lesser-known definition of perturbation: “A deviation of a system, moving object, or process from its regular or normal state or path, caused by an outside influence.” The goal of perturbation-based balance training (PBT) is to use drills and exercises to fine-tune your body’s reaction to anything that might disturb your balance — whether it’s the result of sports, aging or conditions such as a stroke.
How those disturbances are generated during training varies widely, depending on your age, fitness and health status; the actions could involve standing on an unstable surface, for example, or even being pushed. But if you start to fall, you’re doing it right. In fact, you should start to fall about 30 percent of the time per PBT session, says physical therapist Kevin Wilk, associate clinical director at Champion Sports Medicine in Birmingham, Ala., and adjunct assistant professor of physical therapy at Marquette University. “That’s what’s going to produce better motor control changes.”
By experiencing situations where they start to fall and then catch themselves, people can improve their motor control and help minimize their likelihood of falling when they lose their balance in real life, whether on the stairs or the playing field.
How PBT works
According to Robert Donatelli, a Las Vegas-based physical therapist whose patients include professional athletes, Olympians and older adults with neurological impairments, balance largely depends on three factors: vestibular performance, or the functioning of the structures in the inner ear that give your brain information about your position; vision; and proprioception, a.k.a. kinesthesia, or your body’s ability to sense where your limbs are in space and how much force they’ll need to generate for a given movement. If you challenge any one of these systems — by standing on an unsteady surface, for example, or closing your eyes or moving your limbs — “it will make the others work harder,” Donatelli says.
In PBT, the challenges are made to a person’s reactive balance control (the kind that helps you recover when you start to fall), rather than a person’s anticipatory balance control, which helps you maintain balance, says Avril Mansfield, a senior scientist at the Kite-Toronto Rehabilitation Institute, which is part of Canada’s University Health Network, and an associate professor in the physical therapy department at the University of Toronto. That’s why PBT training is also known as reactive balance training. (It’s also called perturbation-based gait training.)
Challenges differ based on fitness levels. For recreational athletes, PBT could involve standing on one leg for 30 seconds with their eyes closed. Elite athletes, however, might do the same and have no problem maintaining their balance; in this case, they might need to move to an unstable surface, such as a Bosu ball, and stand on one leg and catch or kick a ball to test their reactive balance.
Who can benefit
Mansfield says PBT has been shown to prevent falls in people with diagnoses including stroke, spinal cord injury, Parkinson’s disease and traumatic brain injury.
It’s also helpful for anyone over 65, she says, because loss of balance is a normal part of aging. She was the lead author of a double-blind, randomized, controlled study from 2010 that found that PBT significantly reduced older adults’ chances of falling. A 2014 study found that a single session of PBT among healthy adults ages 65 and older cut participants’ fall risk by half.
Although a 2020 study in which high-risk older adults walked on a treadmill found that PBT had no significant bearing on their risk of falling, it concluded that the training did play an outsize role in preventing fall-related injuries. The researchers speculated that the therapy prevented people from experiencing major falls (as opposed to minor falls) or that it better equipped them to partially recover their balance, resulting in a more controlled fall.
In terms of sports, Wilk says, PBT benefits any athletes whose sports require dynamic balance, such as gymnasts, basketball players, skiers, soccer players and trail runners. “Everything ties into this.”
Several studies have found that it can prevent the kinds of injuries typically associated with ball sports, particularly ACL tears, Wilk says. He cites a study that found that college soccer players who included perturbation exercises in their warm-ups reduced their injury rates by nearly half compared with those who did not. The study’s authors note that the exercises increase core muscle activation, creating an “optimal state of physiological readiness.”
It can also help with rehab, he notes. A study involving physically active adults undergoing nonoperative treatment for acute ACL tears found that those who participated in PBT were less likely to experience their knee giving way during sports than those who participated in other forms of rehab. According to Wilk, an ACL tear can compromise joint proprioception. Perturbation training engages the appropriate brain centers to reestablish proprioception skills.
But it’s not for everyone. According to Mansfield, people who should avoid it include anyone with acute trauma, severe osteoporosis, those with weight-bearing restrictions and anyone with cognitive impairments that compromise their ability to understand the purpose of the exercises or to communicate pain or discomfort.
What to expect during a session
Perturbation exercises “don’t have to be complex, they just have to be challenging,” Wilk says. For example, the high-risk older adults who participated in the 2020 treadmill study wore safety harnesses while physical therapists challenged their balance by changing the direction of the belt or abruptly modifying the speed.
A more low-tech option for high-risk or neurologically compromised older adults would be to perform “mini-squats” with their hands on a sturdy table, Wilk says. If that goes well, “then we ask them to take [their] hands away or keep one finger on the table and close [their] eyes and do that squat.”
Tandem or tightrope walking is another option that can be modified to match a variety of ability levels, Mansfield says. This technique requires you to walk while keeping a narrow stance, placing the heel of your front foot directly in front of the toes of your opposite foot. If that’s too easy, try it with your eyes closed and/or on a foam surface — but always under a professional’s supervision.
According to Wilk, “the airplane” is a classic move with variations to meet different ability levels. Stand on one leg with a slight bend in your knee. With your arms outstretched, hinge forward from your hips. When your back is almost parallel to the floor, extend your arms out to your sides and twist your trunk in either direction, as if you’re “landing the plane.”
If that move alone doesn’t challenge your balance, try it while closing your eyes, wearing goggles coated in Vaseline to distort your vision, standing on a piece of foam, wearing a backpack, holding dumbbells, standing on a Bosu ball and/or using a wobble board. If it’s still too easy, don’t be surprised if your trainer or physical therapist gives you an unexpected push.
For capable athletes, imagination is the only factor that limits perturbation training. Donatelli describes working with an elite dancer who could stand on one leg atop a piece of foam resting on an upside-down Bosu ball situated on a platform suspended from the ceiling by several chains. Over time, she developed the ability to maintain her balance while also throwing a ball against a mini-trampoline.
The optimal frequency and duration of your sessions depend on your goals. For those at risk of falling, two to three closely monitored one-hour physical therapy sessions per week is ideal, Mansfield says. One study found that stroke patients who did this for as little as six weeks experienced sustained benefits one year later. Athletes should aim for three 20-minute sessions per week, Donatelli says. But even including a five- to 10-minute session as part of your warm-up or cool-down would be “fantastic,” Wilk says.
Finding a professional
A key part of safe PBT training is finding the right guidance. Make sure your fitness professional or physical therapist has the bandwidth to focus solely on you during your session. “It’s very interactive,” Wilk says. “They need to be really watching you to create the ‘just right’ adaptive challenge.” Although there is no formal certification for perturbation training, Wilk notes that there are graduate programs that focus on motor control.
The guiding principle behind perturbation-based balance training is simple, Wilk says: “A little bit of failure is okay.” That’s not bad life advice, either.
Pam Moore is a Boulder, Colo.-based freelance writer, occupational therapist, speaker, marathoner, Ironman triathlete and ACE-certified personal trainer. She’s also the host of the “Real Fit” podcast.