Instability training is popular in many fitness circles, including CrossFit, HIIT, and yoga. As the name implies, it involves introducing instability to your exercise, usually with external implements. For example, you could utilize an unstable surface like a Swiss ball or Bosu ball, or you could find your instability elsewhere via equipment like suspension trainers.
According to research published in the Sports Health journal, instability training is used for performance enhancement, rehabilitation, and overall musculoskeletal health. The idea is to strengthen the core and trunk muscles and, in certain cases, it can also be used for sport-specific training to prepare athletes who compete on unstable surfaces like sand. Instability exercises may be bodyweight in nature—like standing on a wobble board to improve your balance—or can involve resistance. In both cases, you can look forward to increased core activation, which strengthens your abs, obliques, and lower back.
But what does the science say? One study found that exercises performed under unstable conditions increased trunk muscle activation by an average of 47.3 percent. A stronger core will help you in the long term during exercises like the squat, deadlift, and bench press.
That said, you shouldn’t pair instability training with strength training. For these movements, an unstable base will rob the legs and chest of their full potential, thereby proving detrimental to strength gains. And, if you’re not careful, that unstable base can lead to injury—from literally falling off a tottering platform to tweaking a muscle while trying to balance.
In the study noted above, performing leg extensions while seated on a physio ball resulted in a 70.5 percent drop in force compared to performing the same exercise on a stable bench, and quadriceps activation diminished 40.3 percent. So, it’s a give-and-take scenario. If power output is your goal, stable ground is still king—no one’s winning a powerlifting contest standing on a ball.
Where instability training really shines is preventative care and rehabilitation. David Behm, Ph.D., from Memorial University of Newfoundland writes: “The prevention of lower-back pain and in some cases limb and joint injuries can be based on the ability of the core muscles to anticipate and respond to movement in order to stabilize the vertebral system.” So, training on an unstable surface, which has been shown to improve core strength, can help to prevent joint and lower-back injuries. And it’s not just your core that can benefit from such training.
A Stanford Health Care and Columbia University study looked at how balance training impacts the incidence of ankle sprains in athletes. Instability was achieved by standing on one leg instead of two or by balancing on an unstable surface. Over the study period, athletes who performed the balance training suffered fewer ankle sprains, reducing their risk by 46 percent compared to the control group.
So, should you add instability training to your current regimen? It depends on what you’re hoping to achieve. If you’d like to strengthen your core—and, why wouldn’t you?—then give it a whirl. But for increasing strength and power, stick to stable ground.