Core Muscle Endurance and Side-to-Side Asymmetry in Club-Level Pakistani Fast Bowlers: Protocol for a Cross-Sectional Study

Background: Lumbar bone stress injury is the most time-costly injury in cricket, and fast bowlers carry the greatest burden because the delivery stride imposes repeated, asymmetric trunk loading on a spine that is often still maturing. Pakistani club-level bowlers show a high prevalence of poor core endurance ratios, but no Pakistani study has examined core endurance asymmetry in fast bowlers in relation to side dominance, bowling workload, bowling action and low back pain history. Objective: To describe trunk flexor, extensor and side-bridge endurance, endurance ratios and dominant versus non-dominant asymmetry in club-level Pakistani fast bowlers, and to examine their associations with bowling workload, bowling action and low back pain history as potential markers of lumbar injury risk. Methods: This descriptive, multi-club, cross-sectional study will recruit 216 male hard-ball fast and fast-medium bowlers aged 15–25 years from registered clubs and academies in Lahore, Pakistan (194 required plus a 10% allowance). Core endurance will be measured with the McGill Torso Muscle Endurance Test Battery in a counterbalanced Latin-square order with 5 minutes of rest between tests. Bowling action will be classified from two-dimensional video by two independent raters, and workload will be derived from a structured 28-day recall verified against coach or club records. Planned analysis: Endurance ratios will be analysed as continuous, log-transformed variables, with McGill categories reported descriptively. Dominant and non-dominant endurance will be compared with paired tests, and workload associations will be estimated with multivariable linear regression adjusted for age, BMI, bowling arm, bowling action, test order and low back pain history, with Holm correction for confirmatory tests. Expected outputs: The study will provide the first fast-bowler-specific reference data on core endurance and asymmetry from Pakistani club cricket to inform low-cost screening and conditioning. Findings will be interpreted as potential risk markers, not as predictors of stress fracture.