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Section 9. Physical Education
Selenica Rigerta, Sports University of Tirana, Albania PhD Student in Sport Science Faculty of Movement Science E-mail: [email protected]
The relationship between strength and power of leg muscles in elite sport athletes (Study case)
Abstract: The development of the optimal physical parameters is often determined by basic functional qualities. Dynamic sports require fast direction changes during movement, as accelerations, jumps, sprinting, which are subordinated to ability to produce strength in unit time. It can be argued that peak power depends to great extent on maximal strength. Although these physical qualities are produced from the same group muscles, we must consider that the structure of the movement and the involvement of specific muscles can influence their relationship result in different ways.
The aim of the study was to verify the influence that the static strength parameters of extensor and flexor leg muscles, separately, have on the dynamic maximal relative power in a single and a multiple jumping movement.
Methods: We selected 29 students of the University of Sports of Tirana, active in elite sport. We measured separately the Maximal Static Strength (MSS) of the extensor and flexor muscles of right and left leg in an angle of 90 degrees of the knee, using Force Dynamometer "Easytech". We also measured the maximal relative power on Leonardo Mechanography Platform, through two tests: 1-Simple Two Leg Jump Test (S2LJ); 2-Multiple Two Leg Jump (M2Lj).The data collected were statistically elaborated with Pearson Coefficient Correlation.
Results: There exist a stronger correlation between MSS and S2LJ for the extensor leg muscles than flexor leg muscles but both of them have a moderate correlation with the power expressed in S2LJ. The Right/Left extensors have an R= 0.6572 and 0.6415 and the Right/Left flexors R= 0.5566 and 0.5419. The correlation of MSS and M2LJ is weak with R= 0.4275 and 0.4746 for Right/Left extensors and R= 0.4238 and 0.4609 for the Right/Left flexors. There is not a significant difference in the correlations of M2LJ with extensor and flexor MSS. All results are significant at p<0.05.
Conclusions: The influence of MSS becomes weaker with the increase of the dynamicity and duration of the movement. In dynamic movements the contribution of both extensors and flexors is important.
Keywords: static strength, power, parameters, leg muscles, dynamic movement, jump.
Introduction untary contraction performed at a specific angle
Development the optimal physical parameters of- against an unyielding resistance which in series with a
ten determined by basic functional quality of occur- strain gauge, in our case we use force platform whose
rence of strength [6]. The force production can be transducer measures the applied force that we called
measured by isotonic or isocinetic methods. The iso- Maximal Static Strength (MSS) [7]. Dynamic sports
kinetic measurements involve the use of isocinetic de- require fast direction changes during movement, as ac-
vices. The isometric testing is done by a maximal vol- celerations, jumps, sprinting, which are subordinated
to ability to produce strength in unit time [8; 3]. It can be argued that peak power depends to great extent on maximal strength. Thus from this case we study the relationship between static strength parameters and the relative maximal power parameters in dynamic movement which remains of great importance for better understanding the reciprocity and the influence they have to each other and to their training process [2]. Although these physical qualities are produced from the same group muscles, we must consider that the structure of the movement and the involvement of specific muscles can influence their relationship result in different ways [4]. The aim of the study was to verify the influence that the static strength parameters of extensor and flexor leg muscles, separately, have on the dynamic maximal relative power in a single and a multiple jumping movement.
The relationship between strength and power is a fundamental field ofresearch in sport science. The importance of strength and power in every sport activity is obvious and of great influence on the technical result. But, there also exist a specific influence of both parameters, especially of the quality of strength over that ofpower. This specific influence must be studied and defined because can help in the improvement of the quality of the training efficiency [8].
Method
We selected 29 athletes of the University of Sports of Tirana, active in elite sport. We explained them the protocol and received written consensus for their participation in the study.
We measured separately the Maximal Static Strength (MSS) of the extensor and flexor muscles of right and left leg in an angle of 90 degrees of the knee, using Force Dynamometer "Easytech" see figure 1.
Figure 1. Dynamometer "Easytech"&
We also measured the maximal relative power on Leonardo Mechanography Platform, through two tests: See fig 1.
Single Two Leg Jump Test (S2LJ)
Multiple Two Leg Jump (M2LJ)
The data collected were statistically elaborated with Pearson Coefficient Correlation.
Results:
The results of the measurements and statistical elaboration are presented in the following tables.
Correlation between = P max.kg (W/kg), s2LJ 90 0 test & max power Ext Right, isokinetic test:
The value of R is 0.6572. This is a moderate positive correlation. The P-Value is 0.000107. The result is significant at p<0.05.
Correlation between = P max.kg (W/kg) s2LJ 90 0 test & max power Ext left, isokinetic test:
"Leonardo Mechanography Platform"
The value of R is 0.6415. This is a moderate positive correlation. The P-Value is 0.000179. The result is significant at p<0.05.
Correlation between = P max.kg (W/kg) s2LJ 90 0 test & max power flex Right isokinetic test:
The value of R is 0.5566. This is a moderate positive correlation. The p-Value is 0.001714. The result is significant at p<0.05.
Correlations between = P max.kg (W/kg) s2LJ 90 0 test & max power flex Left isokinetic test:
The value of R is 0.5419. This is a positive correlation. The P-Value is 0.002395. The result is significant at p<0.05.
Correlations between = p max rel/W/kg m2LH test & max power Ext Right, isokinetic test:
The value of R is 0.4275. The P-Value is 0.020713. The result is significant at p<0.05. See graph 1. Figure 1.
20 30 40 50 60
Figure 2. Pmax kg(W/kg) to test s2LO 90° Correlations between = p max rel/W/kg m2LH test & max power Ext Left, isokinetic test:
The value of R is 0.4746. The P-Value is 0.009286. The result is significant at p<0.05.
Correlations between = p max rel/W/kg m2LH test & max power Flex Right, isokinetic test:
The values of R are 0.4238. The P-value is 0.021962. The result is significant at p<0.05.
Correlations between = p max rel/W/kg m2LH test & max power Flex Left, isokinetic test:
The value of R is 0.4609. The P-Value is 0.01186. The result is significant at p<0.05. See graph 2. Figure 2.
Figure 3. Pmax rel/W/kg to test m2LH
Discussion:
According to research studies for the review of this topic and the results that we have obtained have shown that the assessment of static force and its development has a strong potential to predict the power and strength in the display of dynamic movements.
There exist a stronger correlation between MSS and S2LJ for the extensor leg muscles than flexor leg
muscles but both of them have a moderate correlation with the power expressed in S2LJ.
The Right/Left extensors have a R= 0.6572 and 0.6415 and the Right/Left flexors R= 0.5566 and 0.5419.
The correlation of MSS and M2LJ is weak with R= 0.4275 and 0.4746 for Right/Left extensors and R= 0.4238 and 0.4609 for the Right/Left flexors.
There is not a significant difference in the correlations of M2LJ with extensor and flexor MSS. All results are significant at p<0.05.
The influence of maximal static strength (MSS) becomes weaker with the increase of the dynamicity and duration of the movement.
In dynamic movements the contribution of both extensors and flexors is important.
Further implications:
Different studies have used different isometric measurements and dynamic variables, majority of researchers have reported some relationship between the two. Our focus should be that in implementation of training program to show the dynamic variables of strength and power directly and those which were activity related such as running, jumping.
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