(1) THE INFLUENCE OF VASTUS LATERALIS MUSCLE SIZE, ARCHITECTURE, AND PATELLAR TENDON MOMENT ARM LENGTH ON COUNTERMOVEMENT JUMP PERFORMANCE

The countermovement jump (CMJ) is a common assessment employed by strength and conditioning professionals and sports scientists to assess lower extremity performance. Identifying the role of quadriceps muscle size, architecture, and moment arm length on CMJ performance may help inform practitioners on future training strategies.

Purpose: To examine the influence of vastus lateralis (VL) muscle size, architecture, and patellar moment arm (MA_PT) length on CMJ performance.

Methods: Thirty-one recreationally active young adults (18 females; age: 21.77±3.30 years, stature: 173.63±9.46 cm, body mass: 70.92±11.84 kg) volunteered for this investigation. Participants reported to the laboratory on two separate occasions to perform a CMJ assessment (visit 1) and determine VL muscle size and architecture, and MA_PT length (cm) using ultrasonography and dual-energy x-ray absorptiometry, respectively (visit 2). Participants performed three hands-on-hips, no step, CMJ (30 secs of rest between attempts) on a jump mat to determine maximal jump height (cm). The highest jump height was used for analysis. All muscle size and architecture variables were taken from the VL of the dominant limb. Muscle size was defined as total muscle volume (cm³) using the Cavalieri formula that utilized VL cross-sectional area at 25%, 50%, and 75% of muscle length. Fascicle length (FL; cm) was taken from two clearly visible fascicles in the middle of the muscle. The length from the superficial to deep aponeurosis just inside the surrounding fascia was recorded for each and averaged. Additionally, pennation angle (PA; °) was recorded and averaged from the same two fascicles, defined as the angle between the fascicle and deep aponeurosis. The MA_PT length was defined as the perpendicular distance between the tibiofemoral contact point (i.e. the midpoint of the shortest distance between the femoral condyles and tibial plateau) and the patellar tendon action line. Vastus lateralis muscle volume, FL, PA, and MA_PT length were quantified via an open-source imaging program. Pearson product moment correlations (r) were used to determine the association between VL muscle volume, FL, PA, and MA_PT length with CMJ performance. Further, a stepwise regression analysis was used to determine the relative contribution of VL muscle volume, FL, PA, and MA_PT length on CMJ performance. An alpha level of 0.05 was set a priori to determine statistical significance. 

Results: Countermovement jump height was associated with VL muscle volume (r=0.791, P< 0.001), PA (r=0.461;P< 0.01), and MA_PT (r=0.557; P< 0.01). The stepwise regression analysis suggested that both VL muscle volume and FL contributed to CMJ height (R²=0.665; P< 0.001).

Conclusions: Higher CMJ heights were associated with larger VL muscle volume, greater PA, and longer MA_PT. Further, it appears that FL is an important “cofactor” for CMJ performance which becomes increasingly important for those with greater muscle volumes that collectively explains 67% of CMJ height. PRACTICAL APPLICATIONS: Vastus lateralis muscle volume and FL are important predictors of CMJ performance, which are factors that can be modified with resistance training programs. This may be important for strength and conditioning practitioners and sport scientists as these measures can be reliably assessed in the field using ultrasonography.

 


Acknowledgements: None