LOWER-BODY MUSCLE STRUCTURE AND ITSROLE IN JUMP PERFORMANCE DURING SQUAT,COUNTERMOVEMENT, AND DEPTH DROP JUMPSBiomehanikaFakultet sporta i fizikog vaspitanjaUniverzitet u BeograduBeograd, 2015.JACOB E. EARP et al.

Muscle ArchitectureMuscle architecture has been known to be associated with performance and is adaptableto training.

In this study Muscle fascicle thickness Pennation angle Fascicle length were analysed.

Fascicle length = pennation angle x fascicle thickness

Increases in fascicle thickness and pennation angle have been observed with resistance training and are highly correlated with ability to produce force.

A deficit in strength can be observed with an increase in pennation angle.

As pennation angle decreases or fascicle thickness increases, fascicle length will also increase.

The influence of these structures has been associated with running performance,there is no known linkage to jump performance.

Abe found that trained sprinters were heavier, had lesspennation, and had longer and thicker fascicles in the vastuslateralis (VL) and the medial and lateral gastrocnemius (MGand LG) than trained distance runners.

Purpose: To examine the relationship between lower-body muscle structure and vertical jump performance.

Hypothesis:

Methods:

Subjects:25 men performed 2 separate testing sessions .

The first testing session was used to collect anthropometrics and ultrasonography measures.- Height, body mass, VL and LG fascicle thickness and pennation angle Jump testing was done during the second testing session.- SJ, CMJ, and DDJ (Jump height, peak power, and relative power).

Each subject self-reported that they had been involved in at least 6 months of strength training andwere familiar and trained with speed, plyometric, or power training.

All 3 jump types were performed in 2 nonconsecutive sets of 3 jumps in a balanced and randomized order, with the hands on the hips to limit any upper body influence on the jumps.

Statistics:

A paired T-test was used to analyze the differences between jump performance parameters.

Intraclass Rs 0.80 were determined for test-retest reliability of the dependent variables.

Simple and multiple regressions were used to determine the relationships between and among the dependent variables.

Results:

Findings :- Significant predictions of jump performance can be made by accounting for the lower leg muscle architecture of the jumper.

- As preload increases, having specific LG muscle architecture can predict an individuals response to the increased load.

- Only LG muscle structure and not VL muscle structure could predict performance during jumping.

Findings :

- The jump height differences between CMJ and DDJ could be weakly predicted by fascicle length.

- Jump height could be significantly predicted by LG pennation angle for all 3 jump types.

- Absolute power was best predicted by LG muscle thickness, and this relationship was not significantly strengthened when taking into account pennation angle or fascicle length.

- LG pennation angle was the only significant predictor of power.

- The muscle architecture most beneficial for jumping is not necessarily the same for sprinting, suggesting that training specificity be a goal of strength and conditioning coaches when prescribing exercises for athletes.

Practical implications :Muscle architecture can be used to predict jump performance for SJ, CMJ, and DDJ, as well as an individuals response to increase preloads.

Lateral gastrocnemius pennation and thickness were positively related to jump performanceand can possibly be trained to allow for better performance of by improving the weak link in the chain.

Shorter LG fascicle length could also weakly predict the change in jump height between CMJ and DDJ, but more research is needed to understand this relationship.

Sport specificity should be a focus for coaches when prescribing exercises because of the role of the gastrocnemius as a biarticular muscle.