BACKGROUND The purpose of this study was to determine how the combination of plyometric training (PT), which builds strength through fast, repetitive extensions and contractions, and kettlebell training (KT), using a device that is smaller than a barbell and allows for strength and full-body work, affects the physical performance and performance of high school pitchers during the season. MATERIAL AND METHODS Participants (n=30 males; age group=16-19 years) were randomized into 3 groups: compound training group (CTG) (n=10), plyometric training group (PTG) (n=10), and kettlebell group (KTG) (n=10). All groups performed training twice weekly for 4 weeks. Pre- and post-intervention assessments were conducted on isokinetic strength to measure strength, vertical jump (VJ) to measure power, dynamic balance (Y-balance), and ball speed (BS) to measure baseball performance. RESULTS We found there was increased strength, VJ, Y-balance, and BS in the CTG, PTG, and KTG (p=.000). CTG had significantly different results than PTG and KTG (p=.000). There was a significant difference in increased strength of the right knee joint flexors between PTG and KTG (p=.000). CONCLUSIONS CTG, PTG, and KTG for pitchers during the season improved significantly. These results suggest that combination training, rather than just 1 type of training, affects pitchers' strength, VJ, Y-balance, and BS during the season.