Relative Peak Force Research Articles

Comparative Effects of Deep Versus Shallow Squat and Leg-Press Training on Vertical Jumping Ability and Related Factors

Young, previously untrained healthy men (n = 10) and women (n = 8) completed 9 weeks of periodized, machine-based squat training to determine if manipulating range of motion would have a differential effect on vertical jumping ability and related measures. Subjects were pretested and then randomly assigned to 1 of 3 groups: (a) deep squats (n = 6), (b) shallow squats (n = 6), and (c) controls (n = 6). Training took place 3 days per week. Pre-and posttesting included standing (RVJ) and depth (DVJ) vertical jumps for distance; machine deep and shallow squats for 1RM (1 repetition maximum) relative strength; and velocity-controlled squats at 0.51 m·s−1 for relative peak force and at 1.43 m·s−1 for relative peak power. Based on ANCOVA posttest results, the training protocols were ineffective in eliciting improved performance (p > 0.05) in VJ, slow-velocity squatting force, and moderately fast squatting power when performance was compared with the performance of control subjects. Conversely, the group training with deep squats was the only group to perform significantly (p <0.05) better than controls for 1RM shallow squats and significantly (p <0.05) better than both shallow-squat and control groups for 1RM deep squats. Furthermore, the coefficient of transfer for deep squats to both RVJ (2.32) and DVJ (1.68) was substantially greater than for shallow squats (0.31 and 0.11, respectively). It was concluded that deep-squat training appears to elicit the best improvement for both shallow-and deep-squatting performance. However, 9 weeks of machine-based, periodized squat training, regardless of depth, does not appear to appreciably enhance slow-velocity squatting force, moderately fast squatting power, or vertical jumping distance in previously untrained men and women.

Comparative Effects of Deep Versus Shallow Squat and Leg-Press Training on Vertical Jumping Ability and Related Factors

Young, previously untrained healthy men (n = 10) and women (n = 8) completed 9 weeks of periodized, machine-based squat training to determine if manipulating range of motion would have a differential effect on vertical jumping ability and related measures. Subjects were pretested and then randomly assigned to 1 of 3 groups: (a) deep squats (n = 6), (b) shallow squats (n = 6), and (c) controls (n = 6). Training took place 3 days per week. Pre-and posttesting included standing (RVJ) and depth (DVJ) vertical jumps for distance; machine deep and shallow squats for 1RM (1 repetition maximum) relative strength; and velocity-controlled squats at 0.51 m·s−1 for relative peak force and at 1.43 m·s−1 for relative peak power. Based on ANCOVA posttest results, the training protocols were ineffective in eliciting improved performance (p > 0.05) in VJ, slow-velocity squatting force, and moderately fast squatting power when performance was compared with the performance of control subjects. Conversely, the group training with deep squats was the only group to perform significantly (p <0.05) better than controls for 1RM shallow squats and significantly (p <0.05) better than both shallow-squat and control groups for 1RM deep squats. Furthermore, the coefficient of transfer for deep squats to both RVJ (2.32) and DVJ (1.68) was substantially greater than for shallow squats (0.31 and 0.11, respectively). It was concluded that deep-squat training appears to elicit the best improvement for both shallow-and deep-squatting performance. However, 9 weeks of machine-based, periodized squat training, regardless of depth, does not appear to appreciably enhance slow-velocity squatting force, moderately fast squatting power, or vertical jumping distance in previously untrained men and women.

Plantar force distribution in Parkinsonian gait: a comparison between patients and age-matched control subjects.

This study aimed to ascertain whether roll-off of the feet during gait was essentially different in patients with Parkinson's disease from that of elderly control subjects. Twenty-two patients, belonging mainly to Hoehn & Yahr grades III and IV, and 30 elderly people participated in the study. Plantar force distribution data were collected of two consecutive strides using pressure-sensitive insoles as part of the pododynograph system. Results showed that when correcting for gait speed and sex differences, patients with Parkinson's disease walked with significantly lower relative peak forces at the forefoot and heel and increased load at the midfoot. The onset of peak forces indicated slower load acceptance on the heel and early forefoot loading which was confirmed by a reduced amplitude of the centre of force along the length of the foot compared with healthy controls. Roll-off was significantly reduced in patients with Parkinson, a feature which was specific for the disease rather than a result of reduced gait speed alone.

PREDICTION EQUATION FOR STANDING VERTICAL JUMPING DISTANCE: CROSS VALIDATION ANALYSES 587

In this investigation, the validity of a regression equation predictive of restricted standing vertical jumping distance (RVJ) was assessed. This jump eliminates arm swing and antero-posterior torso motion in order to isolate the legs and hips. The estimation sample (X1) included 52 men and 50 women. However, due to the small number of subjects per potential predictor (≈3), cross validity analyses using a holdout sample were not performed. A new validation sample (X2) was acquired including 31 men and 32 women with characteristics similar to those of the original group: age ([horizontal bar over]X1 = 23.0 yrs, [horizontal bar over]X2 = 23.9 yrs), body weight ([horizontal bar over]X1 = 72.4 kg, [horizontal bar over]X2 = 70.9 kg),% fat ([horizontal bar over]X1 = 16.6,[horizontal bar over]X2 = 15.5), and RVJ ability ([horizontal bar over]X1 =.32 m, [horizontal bar over]X2 =.28 m). The original equation for RVJ was:.2494 +.009074 (Relative Peak Squatting Power @ 1.43 m· sec.-1) -.004417 (Relative Peak Squatting Force @ 0.51 m· sec.-1) -.001480 (% Fat). The multiple correlation was.83 and SE was.0452, suggesting the equation accounted for 69% of the variability in jumping performance. To assess validity, residuals were compared for X1 and X2 samples using an independent t-test, correlations between predicted and actual RVJ distances were calculated for the X2 sample, and both the original equation and a new one generated from the hold-out sample were evaluated for parallelism and coincidence of slopes. Residuals were smaller (p <.001) for X2. The correlation between predicted and actual RVJ's for X2 was high (r =.84, p <.001). Slopes for the original equation and a new one based on the X2 sample were parallel (p>.91 for relative peak power and force, and% fat) and coincident (p >.82 for relative peak force and power, and% fat). This suggests the original equation is predictive of RVJ for young, healthy men and women although it tends to slightly under predict. Therefore, it appears that increasing moderately fast relative peak squatting power and reducing both slow-velocity relative peak force and excessive body fat will enhance RVJ performance.

Using Velocity-Spectrum Squats and Body Composition to Predict Standing Vertical Jump Ability

Two equations were developed to predict distance in a restricted standing vertical jump (RVJ). Body composition and strength related variables generated via velocity-spectrum squats were obtained on 52 men and 50 women. Eight squat variables at 4 velocities were selected as potential predictors of RVJ performance. These variables along with body weight, body fat, and gender were used to generate two explanatory regressions. R values ranged from 0.80 to 0.83, and SEE ranged from 0.045 to 0.048 meters for the two equations. Variables with a positive relationship to RVJ were relative peak power at each individual's optimal velocity for power production and at 1.43 m · s–1. Variables with a negative relationship were relative peak force and % body fat. It appears that (a) the more relative squatting power a person can generate at moderately fast squatting velocities, the greater the RVJ distance; and (b) excessive body fat and the ability to generate high relative squatting forces at slow velocities attenuate the predicted distance.

Using Velocity-Spectrum Squats and Body Composition to Predict Standing Vertical Jump Ability

ABSTRACT Two equations were developed to predict distance in a restricted standing vertical jump (RVJ). Body composition and strength related variables generated via velocity-spectrum squats were obtained on 52 men and 50 women. Eight squat variables at 4 velocities were selected as potential predictors of RVJ performance. These variables along with body weight, body fat, and gender were used to generate two explanatory regressions. R values ranged from 0.80 to 0.83, and SEE ranged from 0.045 to 0.048 meters for the two equations. Variables with a positive relationship to RVJ were relative peak power at each individual's optimal velocity for power production and at 1.43 m · s–1. Variables with a negative relationship were relative peak force and % body fat. It appears that (a) the more relative squatting power a person can generate at moderately fast squatting velocities, the greater the RVJ distance; and (b) excessive body fat and the ability to generate high relative squatting forces at slow velocities attenuate the predicted distance.