Eight-week interventional study to evaluate whether lower-body plyometric training alters serum creatine phosphokinase (CPK) and creatinine levels in female collegiate volleyball players. Sixty participants were randomized to experimental (plyometrics twice weekly) or control (routine volleyball) groups. Blood sampling occurred at baseline; days 2, 4, and 6; and weeks 1, 2, 4, 6, and 8.

Intervention adapted from James & Robert (2015). Experimental group completed progressive lower-body plyometrics twice weekly (Monday/Wednesday) over eight weeks with warm-up and cool-down. Exercises included squat jump; jump to box (30 cm); tuck jump; split squat jump; lateral hurdle jump (50 cm); zigzag jump; single-leg tuck jump; and depth jump (80 cm). Control group continued routine volleyball activities and did not perform low/medium/high-intensity plyometrics. Primary biomarker (serum CPK) assessed via CK-NAC optimized IFCC method; serum creatinine by modified Jaffe's method. Two-way ANOVA with Bonferroni post hoc used. Findings: CPK increased from day 2, peaked day 4, stabilized to week 2, then declined toward baseline by week 8; creatinine remained stable.

Inclusion Criteria:

Active collegiate female volleyball players

• consent to participate
• no prior plyometric training program.

Exclusion Criteria:

• Neuromuscular impairments
• recent injuries.

Individual participant data will not be shared because this study does not include a data-sharing plan and is limited to internal analysis only.