Lucas C. Ferreira

Reach Height and Jump Displacement: Implications for Standardization of Reach Determination

Ferreira, LC, Schilling, BK, Weiss, LW, Fry, AC, and Chiu, LZF. Reach height and jump displacement: implications for standardization of reach determination. J Strength Cond Res 24(6): 1596-1601, 2010-Vertical jump performance is often assessed using jump-and-reach tests. The exact procedure used for determining standing reach height and jump height has a large effect on the resultant displacement. The purpose of this investigation was to determine the influence of 4 methods of standing reach height measurement and Vertec™ jump height measurement against 2 force plate methods of jump displacement determination (impulse and flight-time methods). Fifteen men with various training backgrounds performed 2 each of countermovement, restricted (no arm swing) and static start vertical jumps. Reach height was determined using 4 methods; either a 1- or overlapped 2-hand reach, flat footed or with plantar flexion. All jumps were performed on a force platform. The best jump of each type based on Vertec™ displacement was used for analysis. Repeated-measures of analysis of variance for each jump type was used for analysis with Bonferroni post hoc for pairwise comparisons of jump measurement style. All jump displacements for similar types were significantly intercorrelated with a minimum r-value of 0.84. Impulse vs. flight time was the only pairwise comparison of measurement type for which similar values were noted. The one-hand reach with plantar flexion was the method of reach that was closest to the impulse and flight-time methods, and thus should be the preferred choice when using jump-and-reach tests to determine jump displacement. In all cases, the Vertec™ overestimates the displacement of the COM based on force plate methods. When comparing groups of individuals from different data sets, one must consider both the method of reach height (if performed) and jump displacement to make valid comparisons. If plantar flexion with a 1-hand reach is not used during reach measurement, jump displacement will be erroneously high.

Structural and functional predictors of drop vertical jump.

Ferreira, LC, Weiss, LW, Hammond, KG, and Schilling, BK. Structural and functional predictors of drop vertical jump. J Strength Cond Res 24(9): 2456-2467, 2010-This investigation was designed to determine if relatively small manipulations of squat load and the inclusion of selected morphologic variables might augment the explained variance in vertical jump (VJ) displacement. Fifty-two university students (27 women and 25 men) with weight training experience served as subjects. All were assessed for body fat percentage (BF%), height, body weight (BW), leg length (LL), ankle range of motion, and quadriceps angle (Q-angle). Additionally, subjects performed drop vertical jumps (DVJs) and both countermovement jump (CMJ) squats and static jump (SJ) squats at 20, 30, and 40% of their back squat 1 repetition maximum (1RM). A preliminary analysis revealed that DVJcm for all subjects (28.1 ± 6.64; mean ± SD) was most highly correlated with both CMJ @ 30% 1RM (CMJ30PP) and SJ @ 20% 1RM (SJ20PP) (r = 0.84, p < 0.001). Forced multiple regression was then used to determine which variables contributed to VJ displacement. The greatest variability explained (83%) used a CMJ: DVJcm = 20.311 + (0.008) (CMJ30PP) − (0.346) (BW). When the same variables were used to calculate separate gender-based regressions, the explained variance in DVJcm (men = 33.0 ± 5.34 cm; women = 23.4 ± 3.79 cm) was 68% for men and 64% for women. These findings suggest that jump squat peak power at a light load is a good predictor of VJ and that its training-induced augmentation would likely improve VJ. The addition of BW to the equation explained slightly more variability in DVJcm than in BF%. Because excess amounts of either would be an additional load to be moved against gravity (fat in general or skeletal muscle in the upper torso), it follows that relatively high levels of either might be expected to attenuate VJ performance.

Reliability of Goniometry-Based Q-Angle

To establish the stability reliability, precision, and minimum value for detecting real differences for quadriceps angle (Q‐angle) measurements based on standardized protocols and surface goniometry.