Between Team Frequency and Variability of Bimodal Force Time Curves in a Countermovement Jump
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Presenter(s)
Brady Ferguson
Abstract
PURPOSE: The countermovement jump (CMJ) is commonly used to assess performance and fatigue for athlete monitoring and training adaptation. Force–time curves differ across populations, presenting as either unimodal (single peak) or bimodal (two peaks). Distinguishing between these profiles may allow coaches and researchers to group athletes for individualized training and more accurate analysis. Examining team-level CMJ type variability and frequency may support the development of an objective classification method, improving consistency in categorization. METHODS: A retrospective database analysis was conducted on four Division II women’s teams over 16 weeks: track and field (n=17; 21 sessions), gymnastics (n=22; 10 sessions), soccer (n=26; 8 sessions), and basketball (n=13; 7 sessions). Athletes performed three hands-on-hips CMJs per session. Exclusion criteria included lower-body injury within six months, missing more than three consecutive sessions, or fewer than twelve total jumps. Peak and trough force values were extracted from force–time curves and extrapolated into a custom spreadsheet. % Difference between these values was analyzed at the population level and between teams, and bimodal frequency was calculated as the % of athletes on each team that was classified as bimodal at each MPT. Between threshold agreement was assessed on each team using Cohen’s kappa. RESULTS: Soccer and basketball consistently showed higher % Difference than track & field and gymnastics. % Difference between teams was significant in every comparison (p< 0.01) except Track and Field and Gymnastics (p=0.9859). Bimodal classification frequency decreased with increasing MPT across all teams. Cohen’s kappa indicated strong agreement between adjacent MPT after the 4-5% interchange in all teams, and the average kappa value among all teams was highest at the 4-5% interchange. CONCLUSION: CMJ classification is highly dependent on the MPT. Soccer and basketball athletes had more frequent bimodal jumps than track & field and gymnastics at all thresholds, suggesting sport specific differences in CMJ classification. Thresholds of 4% MPT or higher provide more consistent classification across MPT, suggesting a starting point for objective CMJ classification.
College
College of Nursing & Health Sciences
Department
Health, Exercise & Rehabilitative Sciences
Campus
Winona
First Advisor/Mentor
Becky Heinert
Presentation Type
Oral Presentation
Format of Presentation or Performance
Pre-Recorded Video
Closed Captions for Brady Ferguson RCA Day 2026 recorded video
Between Team Frequency and Variability of Bimodal Force Time Curves in a Countermovement Jump
PURPOSE: The countermovement jump (CMJ) is commonly used to assess performance and fatigue for athlete monitoring and training adaptation. Force–time curves differ across populations, presenting as either unimodal (single peak) or bimodal (two peaks). Distinguishing between these profiles may allow coaches and researchers to group athletes for individualized training and more accurate analysis. Examining team-level CMJ type variability and frequency may support the development of an objective classification method, improving consistency in categorization. METHODS: A retrospective database analysis was conducted on four Division II women’s teams over 16 weeks: track and field (n=17; 21 sessions), gymnastics (n=22; 10 sessions), soccer (n=26; 8 sessions), and basketball (n=13; 7 sessions). Athletes performed three hands-on-hips CMJs per session. Exclusion criteria included lower-body injury within six months, missing more than three consecutive sessions, or fewer than twelve total jumps. Peak and trough force values were extracted from force–time curves and extrapolated into a custom spreadsheet. % Difference between these values was analyzed at the population level and between teams, and bimodal frequency was calculated as the % of athletes on each team that was classified as bimodal at each MPT. Between threshold agreement was assessed on each team using Cohen’s kappa. RESULTS: Soccer and basketball consistently showed higher % Difference than track & field and gymnastics. % Difference between teams was significant in every comparison (p< 0.01) except Track and Field and Gymnastics (p=0.9859). Bimodal classification frequency decreased with increasing MPT across all teams. Cohen’s kappa indicated strong agreement between adjacent MPT after the 4-5% interchange in all teams, and the average kappa value among all teams was highest at the 4-5% interchange. CONCLUSION: CMJ classification is highly dependent on the MPT. Soccer and basketball athletes had more frequent bimodal jumps than track & field and gymnastics at all thresholds, suggesting sport specific differences in CMJ classification. Thresholds of 4% MPT or higher provide more consistent classification across MPT, suggesting a starting point for objective CMJ classification.
