Isometric training, conditioning and testing in relation to jump performance: a systematic review

Long-term isometric training, acute conditioning and isometric strength testing share a contraction mode but address different time scales and questions. We treated chronic training as the primary intervention question and the other domains as complementary evidence. The review followed PRISMA 2020. PubMed, Web of Science and Scopus were searched from inception to 20 April 2026. Long-term isometric training was defined as repeated isometric training lasting at least 4 weeks; acute conditioning referred to an isometric activity followed by jump testing within the same experimental session. Methodological quality was assessed using the Effective Public Health Practice Project tool. A structured narrative synthesis was used because designs, comparators, protocols and outcomes were heterogeneous. For controlled chronic studies, reported between-group, group-by-time or between-condition contrasts were prioritized; within-group pre-to-post values were descriptive only when comparative estimates and 95% confidence intervals were unavailable. Twenty-six studies involving 974 participants were included: four long-term training studies ( n = 61), seven acute-conditioning studies ( n = 173), and 15 testing or association studies ( n = 740). The sample comprised 612 men, 281 women and 81 participants with sex not reported; mean ages ranged from 12.5 to 46.4 years. Eight studies were rated strong, 12 moderate and six weak. In the clearest chronic comparison, six weeks of isometric versus traditional strength training produced no group x time difference in CMJ height. Across the four chronic studies, comparative estimates and 95% confidence intervals were incompletely reported, so within-group changes were treated as secondary descriptions rather than intervention effects. Acute post-activation performance enhancement responses varied with protocol and recovery, while testing studies showed task- and metric-specific associations between isometric force variables and jump performance. Observed adaptations after isometric training include increases in force-producing capacity, tendon stiffness, RFD and selected jump outcomes, but these observations should not be equated with effects relative to a comparator. Limited comparative chronic evidence does not establish a consistent advantage of isometric training for CMJ, SJ or DJ performance. Acute conditioning and isometric strength testing should be interpreted as separate same-session and assessment questions rather than as evidence of chronic training efficacy.