Situational characteristics of lower limb muscle cramps in male semi-elite football players: a video-based descriptive case series

Lower limb muscle cramps are a common yet under-researched acute condition in semi-elite football, and empirical evidence regarding their situational characteristics remains scarce. This study aimed to systematically explore the temporal-spatial situational characteristics, short-term exercise loads, and position-specific distribution patterns of lower limb muscle cramps in male semi-elite football players. This study used a descriptive case series design. Match videos from 85 games of the 2025 season of the Jiangsu Provincial City Football League were systematically reviewed. Based on strict inclusion criteria, 38 cases of lower limb muscle cramps that directly led to forced substitution in male semi-elite football players were identified. Descriptive statistics were used to systematically characterize the timing of cramp occurrence, the direct triggering actions, the high-intensity exercise load in the 15 min preceding the cramp, the playing position distribution, the injury mechanism (indirect-contact / non-contact), and the kinetic chain type (open-chain / closed-chain). All 38 cramp cases occurred during the second half of matches, with the 60–75 min interval being the absolute peak period (42.1%). Regarding position distribution, defenders had the highest frequency of cramp episodes (50.0%), whereas midfielders exhibited the highest high-intensity exercise load in the 15 min prior to cramp onset (median: 14.0 actions). Jumping/landing cushioning was the most frequent direct triggering action (36.8%). Furthermore, the vast majority of cramps involved a non-contact mechanism (84.2%) and were highly concentrated in the closed-chain kinetic state of lower-limb weight-bearing (84.2%). This descriptive case series study establishes the baseline characteristics of lower limb muscle cramps in male semi-elite football players within real-world match contexts. Cramp episodes in this population demonstrate a pattern of late-match clustering and a higher vulnerability among defenders, with the majority triggered by closed-chain movements such as jumping and landing. Distinct position-specific patterns were observed across cramp timing, short-term exercise loads, and triggering situations, suggesting that future injury prevention interventions and fatigue monitoring protocols should prioritize dynamic management tailored to playing position characteristics.