Squat Power Research Articles

Changes in exercise characteristics, maximal voluntary contraction, and explosive strength during prolonged tennis playing

Objectives: To examine changes in exercise characteristics, maximal voluntary contraction, and explosive strength during prolonged tennis playing. Methods: Maximal isometric voluntary contraction (MVC), leg stiffness (hopping), and peak power in...

Association Of Vertical Jump Performance To Jump Squat Power Expressions

PURPOSE To establish the association in young men of vertical jump (VJ) displacement with various expressions of power obtained during parallel jump squats (PJS). METHODS Subjects were 48 men (age 22.9 ± 4.17 y; bwt 83.3 ± 14.55 kg) with resistance-training backgrounds. Subsequent to 3 practice sessions, displacement was determined for 4 different VJ styles: restricted (RVJ), non-counter movement (NCMVJ), standing (SVJ), and drop (DVJ). At a different time, each subject's 1RM parallel squat (≥ body wt) was determined for standardizing loading on subsequent tests. Within one week, subjects performed maximal PJS with an external load of 30% 1RM. A computer-interfaced dynamometer tethered to the barbell measured bar velocity while power was calculated based on load, acceleration, and velocity. The associations between displacement for the 4 styles of VJ and squat power expressions were determined using inter-class correlations. RESULTS ARPD is the aver rate of power devp from the onset of concentric movement to either peak or start position. Start gradient is the power @ 50% of time to start position/respective elapsed time, and acceleration gradient is the power @ start position/ respective elapsed time for the 2nd 50%. Means, std dev, and associations are reported in Table 1.Table 1: Means, standard deviations, and correlations of four styles of vertical jump and jump squat external power variable acquired at a 30% 1RM load.CONCLUSIONS When expressed relative to body wt, pk power, aver power to pk, and aver power to start position for jump squats performed with a 30% 1RM load were most highly associated (moderate) with the four styles of VJ. A myriad of other power expressions were less associated with VJ displacement. Table 1. Means, standard deviations, and correlations of four styles of vertical jump and jump squat external power variables acquired at a 30% 1RM load. load were most highly associated(moderate) with the four styles of VJ A myriad of other power expressions were less associated with VJ displacment.

Association Of Vertical Jump Performance To Jump Squat Power Expressions

PURPOSE To establish the association in young men of vertical jump (VJ) displacement with various expressions of power obtained during parallel jump squats (PJS). METHODS Subjects were 48 men (age 22.9 ± 4.17 y; bwt 83.3 ± 14.55 kg) with resistance-training backgrounds. Subsequent to 3 practice sessions, displacement was determined for 4 different VJ styles: restricted (RVJ), non-counter movement (NCMVJ), standing (SVJ), and drop (DVJ). At a different time, each subject's 1RM parallel squat (≥ body wt) was determined for standardizing loading on subsequent tests. Within one week, subjects performed maximal PJS with an external load of 30% 1RM. A computer-interfaced dynamometer tethered to the barbell measured bar velocity while power was calculated based on load, acceleration, and velocity. The associations between displacement for the 4 styles of VJ and squat power expressions were determined using inter-class correlations. RESULTS ARPD is the aver rate of power devp from the onset of concentric movement to either peak or start position. Start gradient is the power @ 50% of time to start position/respective elapsed time, and acceleration gradient is the power @ start position/ respective elapsed time for the 2nd 50%. Means, std dev, and associations are reported in Table 1.Table 1: Means, standard deviations, and correlations of four styles of vertical jump and jump squat external power variable acquired at a 30% 1RM load.CONCLUSIONS When expressed relative to body wt, pk power, aver power to pk, and aver power to start position for jump squats performed with a 30% 1RM load were most highly associated (moderate) with the four styles of VJ. A myriad of other power expressions were less associated with VJ displacement. Table 1. Means, standard deviations, and correlations of four styles of vertical jump and jump squat external power variables acquired at a 30% 1RM load. load were most highly associated(moderate) with the four styles of VJ A myriad of other power expressions were less associated with VJ displacment.

Determining the Optimal Load for Jump Squats: A Review of Methods and Calculations

Dugan, E.L., T.L.A. Doyle, B. Humphries, C.J. Hasson, and R.U. Newton. Determining the optimal load for jump squats: A review of methods and calculations. J. Strength Cond. Res. 18(3):668–674. 2004.—There has been an increasing volume of research focused on the load that elicits maximum power output during jump squats. Because of a lack of standardization for data collection and analysis protocols, results of much of this research are contradictory. The purpose of this paper is to examine why differing methods of data collection and analysis can lead to conflicting results for maximum power and associated optimal load. Six topics relevant to measurement and reporting of maximum power and optimal load are addressed: (a) data collection equipment, (b) inclusion or exclusion of body weight force in calculations of power, (c) free weight versus Smith machine jump squats, (d) reporting of average versus peak power, (e) reporting of load intensity, and (f) instructions given to athletes/participants. Based on this information, a standardized protocol for data collection and reporting of jump squat power and optimal load is presented.

Determining the optimal load for jump squats: a review of methods and calculations.

There has been an increasing volume of research focused on the load that elicits maximum power output during jump squats. Because of a lack of standardization for data collection and analysis protocols, results of much of this research are contradictory. The purpose of this paper is to examine why differing methods of data collection and analysis can lead to conflicting results for maximum power and associated optimal load. Six topics relevant to measurement and reporting of maximum power and optimal load are addressed: (a) data collection equipment, (b) inclusion or exclusion of body weight force in calculations of power, (c) free weight versus Smith machine jump squats, (d) reporting of average versus peak power, (e) reporting of load intensity, and (f) instructions given to athletes/ participants. Based on this information, a standardized protocol for data collection and reporting of jump squat power and optimal load is presented.

The Effects of an In-Season of Concurrent Training on the Maintenance of Maximal Strength and Power in Professional and College-Aged Rugby League Football Players

Fourteen professional (NRL) and 15 college-aged (SRL) rugby league players were observed during a lengthy in-season period to monitor the possible interfering effects of concurrent resistance and energy-system conditioning on maximum strength and power levels. All subjects performed concurrent training aimed at increasing strength, power, speed, and energy-system fitness, as well as skill and team practice sessions, before and during the in-season period. The SRL group significantly improved 1 repetition maximum bench press (1RM BP) strength, but not bench throw (BT Pmax) or jump squat maximum power (JS Pmax) over their 19-week in-season. The results for the NRL group remained unchanged in all tests across their 29-week in-season. The fact that no reductions in any tests for either group occurred may be due to the prioritization, sequencing, and timing of training sessions, as well as the overall periodization of the total training volume. Having athletes better conditioned to perform concurrent training may also aid in reducing the possible interfering effects of concurrent training. Correlations between changes in 1RM BP and BT Pmax suggest differences in the mechanisms to increase power between stronger, more experienced and less strong and experienced athletes.

The Relation Between Strength and Power in Professional Rugby League Players

The purpose of this investigation was to analyze the relation between measures of maximal strength and maximal power generated during exercises with similar movement patterns. Twenty professional rugby league players were examined for maximal strength in a 3 repetition maximum (RM) full squat and 3RM bench press exercise and for maximal power during a jump squat and incline bench press throw exercise. A 3RM power clean from the hang was also examined to determine if this exercise was related to lower or upper strength and power. The results indicate that maximal strength is highly related to maximal power in all the tests performed (r = 0.55–0.89, p ≤ 0.05). The power clean from the hang is related more to lower-body squat strength and jump squat power (r = 0.79) than to upper-body bench press strength or incline bench throw power (r = 0.51–0.55). The practical application of this data suggests that while strength and power are highly related, a large degree of variance still exists. This may imply that further specific power training may be warranted to maximize power development, especially for the upper body.

The Relation Between Strength and Power in Professional Rugby League Players

The purpose of this investigation was to analyze the relation between measures of maximal strength and maximal power generated during exercises with similar movement patterns. Twenty professional rugby league players were examined for maximal strength in a 3 repetition maximum (RM) full squat and 3RM bench press exercise and for maximal power during a jump squat and incline bench press throw exercise. A 3RM power clean from the hang was also examined to determine if this exercise was related to lower or upper strength and power. The results indicate that maximal strength is highly related to maximal power in all the tests performed (r 5 0.55‐0.89, p # 0.05). The power clean from the hang is related more to lower-body squat strength and jump squat power (r 5 0.79) than to upper-body bench press strength or incline bench throw power (r 5 0.51‐0.55). The practical application of this data suggests that while strength and power are highly related, a large degree of variance still exists. This may imply that further specific power training may be warranted to maximize power development, especially for the upper body.

Measurement of elastic-like behaviour in the power squat

Because traditional procedures of evaluating elastic-like behaviour have yielded mixed results, the purpose of this work was to explore two methods of measuring elastic-like behavior in the power squat. The entire concentric time method was based on traditional procedures. The initial concentric time method was developed to examine elastic-like behavior for the beginning 0.2 s of concentric movement. The present study compares a power squat performed maximally by nine subjects at 70% of their 1 repetition maximum. Squats were performed with rebound (REB) and without rebound (NRB). For the entire concentric time method only concentric time was significantly greater (p < 0.05) in the NRB than the REB. For the initial concentric time method the relative displacement, velocity, net work, & peak power of the center of mass were significantly greater (p < 0.05) in the REB than the NRB. Some subjects had theoretically infeasible negative results for elastic enhancement in the entire concentric time method, but not the initial concentric time method. It seems that measuring elastic-like behavior near the end of the movement can be confounded by the constraints of the task. Based on its success, the initial concentric time method appears to be more appropriate for measurement of elastic-like behavior in lifting.

The effect of exercise on anterior-posterior knee laxity.

A commercial knee laxity testing device was used to quantitate anterior and posterior laxity before and after exercise. Measurements were made at 20 degrees of knee flexion and with a displacement force of 133 N (30 pounds). In sedentary controls no significant change in laxity was noted over 2 hours. Squat power lifters sustained no significant change in laxity after a series of squats (0.4 to 0.7 cm) using 1.6 times body weight. However, 18% to 20% increases in mean anterior and posterior laxity were noted in college basketball players after 90 minutes of practice and in recreational runners after a 10 km race. The role of muscle relaxation in such tests was also evaluated by measuring laxity in normal knees before and during general anesthesia. Negligible laxity change was noted. Thus, functionally "complete" muscle relaxation can be obtained during testing in the cooperative individual. In conclusion, basketball players and distance runners experienced a transient increase in anterior and posterior laxity during exercise. Power lifters doing squats did not demonstrate a significant change in laxity. It appears that repetitive physiologic stresses at a high strain rate produce significant ligamentous laxity, while a relatively few large stresses at a low strain rate do not.