Over the past 2 decades, stability training has become a major niche within the exercise the community. Stability balls, bosus, wobble boards and many other devices have found their way into gyms. Oddly, many of these devices have been around for decades but in very specific markets. Stability balls, also known as Swiss balls were developed in the 1960s for rehabilitation of children with neurodegenerative disorders. The indo board was originally developed in the 1990s by surfers when school and jobs took them inland away from the beach.
There is nothing wrong with adding a stability component to training if one understands it’s use and integrates it properly. I spent a cycle squatting on a stability ball and jumping on a bosu. The problem is when people use these modalities and believe they are developing real strength. These modalities are not about strength, they are about kinesiological awareness and neuro-muscular coordination.
One blip of a fad was to replace office chairs with swiss balls. Yet the evidence, for example Gregory, et al 2006, indicates that while there is p = 0.035 increase in thoracic muscle activation, workers also reported increased discomfort p =0.0001. Stanton et al, 2004 divided a university running club, one group trained normally and one added in stability ball training. After 6 weeks of 3xwk training with the ball, core stabilization was improved but no increase in abdominal or back musculature was reported by EMG, VO2, running economy and running posture were also unchanged. It improved stability but not performance for runners. Yongming, et al 2013 compared EMG of the 4 heads of the quadriceps squatting at 30% and 60% of max load on the ground and on a wobble board. They found no statistical difference in the data. If the wobble board has a training effect- it is not on the prime movers.
Many who practice sports have little time to train in the gym. Unless stability is a major factor (eg: surfing, halfpipe skateboarders, motocross) then why would you use this modality for multiple cycles? You would be much better served with the classic barbell and dumbbell lifts. Even kettlebells and weight vests provide better stimulation for adaptation. Choose how you invest your precious training time.