The use of Ki to "psych-up" and increase strength
In many modern sports where an explosion of power/strength is necessary, such as weight lifting, shot put, and tennis, athletes often yell or grunt to "psych-up" and improve performance. Martial artists have been using a similar technique for centuries called a "kiap". Unfortunately, there is little scientific evidence that yelling or kiaping improves performance. Therefore, this study examined the effect of kiaping on strength during a handgrip exercise in novices and experts. Fifty participants (25 novice and 25 expert martial artists) completed a handgrip strength test under three conditions, a baseline test, a no kiap control condition, and a kiap condition. Strength increased by a mean of 8% (p < 0.001) for the combined expertise levels in the kiap condition compared to the baseline and no kiap conditions. There was also a significant interaction (p < 0.05) between expertise level and condition, with a medium effect size of 0.48 for novices and a small effect size of 0.25 for experts. The results of this study indicate that the kiap may increase hand grip strength in participants with as little as two months of training, benefiting novices slightly more than experts, and additional training may not result in further increases in strength.