前言：本研究旨在個案追蹤分析優秀棒球選手在打擊狀況佳與差時，握力、30公尺衝刺速度、視覺疲勞、動體視力、眼球運動以及揮棒速度之變化情形，以釐清影響打擊表現之可能因素。方法：5名甲組優秀棒球選手為受試者，以全國成棒甲組春季聯賽二階段的打擊率成績定義其打擊狀況之佳與差。結果：發現棒球選手在打擊狀況差時，握力、視覺疲勞、動體視力-水平、動體視力-綜合及眼球運動有變差之現象，但與打擊狀況佳比較時則未達統計上的顯著差異(p＞.05)；進一步以個案分析則發現，每位受試者在打擊狀況差時，其基本體能、視覺能力及揮棒速度等變項有不同程度的變化。結論與建議：本研究認為在探討打擊狀況優劣時，宜針對基本體能、視覺能力、揮棒速度等面向進行個案受試者的分析，以了解打擊狀況差的影響因素，繼而能調整打擊狀況並提升打擊表現。

Purpose: to investigate difference of grip strength, 30m sprint speed, visual fatigue, dynamic visual acuity (DVA), eye movement (EM) and swing velocity between excellence and slump batting performance conditions for understanding which variable affects on batting performance. Method: 5 elite baseball players recruited from first-class baseball team in Taiwan and voluntary participated in this study. The batting performance condition was defined as 0.300 of batting average during The Springtime First-Class Baseball Tournament in Taiwan. Results: The grip strength, visual fatigue, DVA and EM have slight decreased during the slump of batting performance, but it was not statistical significance compare to those during the excellence of batting performance (p>.05). In the analysis of each player, the physical fitness, visual ability and swing velocity had worse individually during the slump of batting performance. Conclusions: The findings suggested that the physical fitness, visual ability and swing velocity should be analyzed for elite baseball player, when player tries to recovery batting performance condition from slump to excellence. To monitor those variables which affects on batting performance condition would be help to maintain or improve batting performance.