Exploratory Analysis of Skeletal Muscle Architecture and Force-Time Strategy Under External Load in Collegiate...

Objectives: Skeletal muscle architecture (SMA) defines the mechanical limits of force production. However, its associations with force-time strategy under externally loaded conditions have received little research attention. This exploratory study examined associations between vastus lateralis (VL) and lateral gastrocnemius (LG) architecture and force-time strategy, jump-height retention, and stretch-shortening cycle (SSC) transfer-efficiency in collegiate basketball players. Methods: Seventeen collegiate male basketball players completed B-mode ultrasonographic assessment of VL and LG architecture, including muscle thickness, pennation angle (PA), and fascicle length. Athletes performed the squat jump (SJ), loaded squat jump (LSJ), countermovement jump (CMJ), and loaded countermovement jump (LCMJ) on force platforms, with a 20 kg external load applied for loaded conditions. Loaded retention, defined as the percentage of jump height preserved under load, was proposed as a unified construct. Pearson's correlations were calculated, with Benjamini-Hochberg false discovery rate (FDR) corrections applied within predefined functional groups and pooled across morphology-sensitive correlations. Results: LG PA showed a large negative association with LCMJ rate of force development (r = -0.68 [-0.87, -0.30]) and a large positive association with LCMJ time to peak force (r = 0.68 [0.29, 0.87]), both surviving within-group FDR correction. VL PA was associated with eccentric acceleration time and concentric time across jump conditions (r = 0.52 to 0.61), interpreted as exploratory. Transfer-efficiency indices showed no significant associations with SMA, except for the LCMJ/LSJ concentric time ratio, which showed a moderate negative association with LG PA (r = -0.49 [-0.79, -0.01]). Conclusions: Resting muscle architecture was associated with the temporal and rate characteristics of force expression under load, rather than with the gross preservation of jump height. Integrating architectural assessment with loaded force-time profiling warrants further investigation as a means of characterizing individual force-development strategies.