Effects of a Minimal-Dose, Short-Duration Core Training Program on Core Function and Athletic Performance in Elite Female University Ice Hockey Players in Japan: A Case Series.

Female university ice hockey players in Japan often have limited opportunities to perform additional conditioning because of demanding academic schedules and regular team training. Consequently, brief and practical exercise programs that can be incorporated into daily routines are needed. We report a prospective case series evaluating the feasibility and potential effectiveness of a minimal-dose core training program consisting of a 30-second prone static plank performed three times per week. Three elite female university ice hockey players (one in her late teens and two in their early 20s), all with youth national team experience and competing in Japan's highest-level women's league, participated in this 24-week prospective case series conducted using a BAB single-case experimental design. Participants completed an initial eight-week intervention period, an eight-week withdrawal period, and a second eight-week intervention period while continuing their usual team training. Core function was evaluated using the Sahrmann Core Stability Test (SCST) and Seated Side Tapping Test (SST), athletic performance was assessed using the sit-up test and 40-yard dash, and body composition was measured by bioelectrical impedance analysis. Improvements in SCST, SST, and sit-up performance were consistently observed during the intervention phases, whereas performance plateaued or declined during the withdrawal phase. Sprint performance and body composition changed minimally throughout the study. All participants reported excellent adherence to the program without interference with university life and described increased body awareness and motivation toward training. This case series suggests that an extremely brief, high-frequency core training program may improve core function and muscular endurance through neuromuscular adaptation rather than muscle hypertrophy. Although the findings are limited by the small number of participants, this practical intervention may represent a feasible conditioning strategy for elite student-athletes with limited training time.