In volleyball, the skill of blocking, in which a player or players jump and extend their hands above and over the net (without touching the net) to block an attack (spike) by the opponent, is crucial to team success (Eom and Schutz, 1992; Lenberg, 2004). Effective blocking in volleyball is partially dependent upon forceful jumping in order to elevate the body center of mass (COM) as high as possible in order that the hands can reach the greatest possible height (Farokmanesh and McGown, 1988). Further, hand penetration through the plane of the net has importance in taking away possibilities from the attacking player by reducing the set of directions in which the ball can be hit (Farokmanesh and McGown, 1988; Lenberg, 2004).
A recent study has shown that jump height, hand penetration, and time to get hand above the net vary with the choice of a traditional blocking technique versus a swing blocking technique (Neves et al., 2011). Both techniques feature similar footwork, called the approach. In the traditional technique, the player makes the approach with the hands held neutrally in front of the shoulders (see Figure 1a). In the swing technique, the approach is made while allowing the arms to swing lower, similarly to the approach used by an attacker (see Figure 1b).
[FIGURE 1 OMITTED]
This added arm swing causes the jumping motion of the blocker to be more like that of a countermovement jump. In general, arm swing, like that used in a countermovement jump, allows for greater elevation of the COM compared to using less arm swing (Harman et al., 1990, Lees e. al., 2004; 2006; Shetty and Etnyre, 1989). Jump height achieved in countermovement jumping is also correlated to height achieved in spike jumping for the attacker (Wagner et al., 2009), and it seems reasonable that the swing blocking technique also benefits from the countermovement. It has been shown that in blocking the swing technique allows for better COM height and hand penetration (Neves et al., 2011), but the full effect of technique choice on lateral horizontal jumping velocity and the time required to execute the jumping approach remains unclear.
Because the body COM path is determined during takeoff and unchangeable in the air, differences in this horizontal velocity between techniques could lead to differences in the ability of the athlete to adjust to attacks and misdirection once airborne. Additionally, it is unknown what effect, if any, the swing technique has on the effective blocking area a player can cover with their hands and the time over which this area is presented.
The effect of technique choice on horizontal velocity and blocking coverage should be investigated in order to provide further information to practitioners about the potential advantages and disadvantages. The potential for greater blocking coverage above the net should be considered, along with any effects of horizontal jumping velocity on game play.
Therefore, the purpose of this study was to compare traditional technique to swing technique in terms of body COM airborne motion and effective blocking coverage. It was hypothesized that the swing technique would feature a greater lateral horizontal takeoff velocity of the body COM and would allow for greater blocking coverage.
The study was first approved by the Institutional Review Board and nine female NCAA Division I intercollegiate volleyball players (age: 20.9 [+ or -] 1.9 years; height: 1.85 [+ or -] 0.05 m; mass: 76.3 [+ or -] 7.8 kg) volunteered to participate. Subjects were free of injury and cleared for activity by team medical staff at the time of the study. After signing an informed consent form, each individual completed a five-minute dynamic warm-up routine followed by practice blocks of each style until feeling comfortable in their ability to do both successfully. The majority of the participants had been trained in both blocking patterns but was much more familiar with the traditional technique and required less time to practice that method.
Each participant was asked to execute six successful blocking trials; three of the swing method and three of the traditional method, which were executed in a counterbalanced order. Each subject started in a "ready" position with both feet within in a rectangle marked on a volleyball court. This rectangle was 82.5 cm by 45 cm and was marked 30 cm from the court's centerline such that its long axis was parallel to the plane of the net and exactly centered at the midpoint of the centerline.
A blue square "target" was affixed to the top of the net in order to provide the blocker with a location at which they should make the block. This target was placed on the net's top at a distance of 150 cm from the antenna denoting out of bounds. Subjects were asked to jump maximally, as though in game conditions, and to block as though an attack were coming from a point as high as possible above the blue tape (see Figure 2). Therefore, each subject started from the middle of the court and moved rightward a distance of 3.0 m to execute each block as though the opponent's attack was coming from above the blue target. This was done in lieu of using a ball or lives attack in order to standardize the point of attack to allow for comparison between trials and conditions. One researcher with volleyball expertise, as both a Division I collegiate player and coach, verified on a per-trial basis that the technique used was the correct one called-for in the counterbalanced order and that the target was between the extended arms of the blocker while the hands were above the net. If the blocker did not keep the target between the arms, the trial was repeated. Blockers were highly...