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Study aim
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Comparing the effects of three training models (plyometric, traditional, and combined) on skill control (spike and block speed and accuracy) and motor performance (sprint speed, agility, explosive power, and balance) in professional male volleyball players aged 18‑30 years.
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Design
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Randomized controlled trial, single‑blind (outcome assessors), parallel three‑intervention‑group, pre‑test/post‑test, sample size 45, software randomization, phase not applicable.
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Settings and conduct
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Tarbiat Modares University. After screening and consent, 8‑week intervention in standard hall under expert trainer supervision. Assessments by blinded assessors at pre‑test and post‑test.
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Participants/Inclusion and exclusion criteria
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Inclusion: male volleyball players 18‑30 years; at least 3 years of league experience; no musculoskeletal injury in last 6 months; no performance‑affecting medications; no chronic disease; consent.
Exclusion: history of severe knee, ankle, or back injury; uncontrolled heart disease or diabetes; anti‑inflammatory or steroidal medication use; inability to balance for 30s; history of lower limb or spinal surgery.
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Intervention groups
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Plyometric group: 8 weeks, 3×45min/week, explosive exercises including box jumps, tuck jumps, split squat jumps, lateral zigzag hops, and drop jumps. Traditional group: 8 weeks, 3×45min/week, resistance and aerobic exercises including steady running, squats, lunges, and abdominal exercises.
Combined group: 8 weeks, 3×45min/week, combining 20 min plyometric and 20 min traditional training.
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Main outcome variables
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Skill control (spike and block speed and accuracy using digital timer and accuracy recording); motor performance (20‑m sprint speed using timer; agility using T‑test; explosive power using vertical jump; balance using single‑leg stance with eyes closed).