Increase Vertical Leap and Improve Jumping Ability with Plyometrics

Plyometric Exercises to Make You Jump Higher and Further

Article at a glance:

Being able to jump well is crucial for performance in a number of sports, requiring good conditioning and technique. John Shepherd examines the theories and practical strategies that can help you maximise your vertical and horizontal jumping ability and so enhance your sporting prowess

The standing long jump and sergeant jump measure the ability to jump for distance and for height respectively (from a standing two-footed position), and are often used as tests of sports ability. Table 1 (below) displays relative standards for standing long jump (distance) ability. At first sight, this type of jump appears pretty straight forward; the athlete simply bends their knees, whilst swinging their arms back and forward, before making their leap into the pit. However, even this relatively simple jump can be improved technically in one training session, perhaps adding 10cm or more to the distance jumped.

A study by Australian researchers focused on the optimum take-off angle for standing long jumps (1). They discovered that jumping distance was strongly influenced by the jumper’s take-off speed and take-off angle. High take-off angles resulted in poor jump distances, as the athlete was unable to generate sufficient horizontal velocity to propel their bodies forward. The researchers discovered that take-off angles of 19-27 degrees optimised jumping distance and that this was actually lower than the jumper’s preferred angle of take-off (31-39 degrees).

Role of arms in jumping

The use of the arms and free leg (when jumping from one leg) are, like angle of take-off, equally important determinants of jump distance. In an effort to discover exactly how much contribution the arms make to standing long jump distance, researchers from the University of Texas used computer modelling to investigate what effect free and restricted arm movements had (2). They found that simulated jump distances were 40cm longer when arm movements were free. Arm movement allowed for a 15% increase in jump velocity of the centre of gravity.

More specifically, this was attributed to an additional 80 joules of propulsive work done by the shoulder muscles. In order to benefit from this extra energy during sports activity, you need to vigorously swing your arms back and forward as they rise and fall with your thigh movements, timing the arm swing past your legs to coincide with the leg drive into your take-off. This will maximise jump speed (provided of course you aim for a take-off angle of between 19-27 degrees). Arm action is crucial to optimum performance, whatever the jump.

The high jump is the ultimate test of vertical jumping ability. The men’s world record stands at an incredible 2.45m and was set by Cuba’s Javier Sotomayor in 1993. Researchers from John Moores University in the UK, have looked specifically at how the free limbs are used by elite high jumpers in generating vertical velocity (3).

Six elite male high jumpers were subject to tests that enabled the researchers to determine the power and speed of the jumper’s joint motions at take-off. It was discovered that the arms had a greater influence on take-off performance than the free leg. This seemed to be as a result of the limited ability of the free leg to drive further ‘into’ the jump once the take-off foot was grounded and extending into the jump, and was in contrast with the ability of the arms to drive more forcibly ‘through’ into the jump.

In all it was estimated that the free limbs contributed 7.1% of whole-body momentum at take-off. The researchers concluded that in order to maximise the contribution the free limbs can make to performance, the arms should have a vigorous downward motion at touch-down (take-off) to make the most use of the high (but little changing) relative momentum of the free leg.

Foot contact

Such detail can even be extended to foot contact when jumping. Researchers looked at the relevance of foot positioning, and in particular foot-landing positions, when athletes performed depth jumps drills (4). These exercises develop plyometric leg power and require the performer to step off of a suitable platform and on landing, spring immediately upward, sideways or forwards. Specifically, the researchers addressed the force generated from flat-footed versus forefoot ground contacts.

Ten healthy male university students performed two types of depth jump from a 0.4m high box placed 1m from the centre of a force plate. They performed jumps down onto either the balls of their feet (without the heels touching the ground during the subsequent vertical jump), or onto their heels (flat-footed). The researchers discovered that the first (landing) and second (subsequent jump) peaks in force generation were 3.4 times greater and 1.4 times lower respectively for flat-footed landings as opposed to forefoot landings.

For athlete and coach this type of research has some important implications. Specifically, the nature of jumping foot-strike (ground contact) should be carefully analysed for particular sports and the most appropriate jumping exercises performed that have the greatest sports match. For example, while a flat-footed landing depth jump will develop some jumping power, it may not optimally transfer into the specific performance requirements of an athlete in a specific sport. To give some examples:

  • A sprinter may benefit more from forefoot, single-leg-landing depth jumps, as the sprint action is performed from a similar foot-strike position;
  • A basketball or volleyball player may derive greater vertical spring (a key requirement of their games) by using flat-footed, single- and double-leg-landing depth jumps.

As the previous research indicates, the free-limb actions also have to be carefully considered and training drills designed to replicate these. Thus high jumpers, when performing depth jumps, should employ a double-arm shift action (where both arms are driven back and forward and ‘up’ into the jump at take-off) to mimic the specifics of their event. They should also emphasise single-leg landing jumps. Doing this will maximise the transference of the conditioning drill into actual event performance.

Leg stiffness

The long jump is ultimate test of horizontal jumping and long jump research provides equally prescriptive and detailed findings. For example, researchers from Germany looked at the athlete’s centre of gravity during the take-off phase (5). The researchers focused on a number of contributory factors, one of which was the ‘leg stiffness’ of the jumpers’ muscles.

Leg stiffness refers to the tensile properties of muscle. Using an analogy, suppose that a long jumper’s legs were made of plasticine. Even if the athlete could make it down the runway, the take-off leg would instantly buckle under the forces required to launch the athlete off the runway.

However, now suppose our athlete’s legs were made of carbon fibre; there would now be little if any yielding and the jumper would very efficiently transfer their horizontal velocity into the jump. Obviously, long jump athletes (and other jumpers) do not want plasticine legs, but would they benefit from carbon fibre-like stiffness? The German researchers concluded that while there is a minimum standard of leg stiffness required for maximum long jump performance, further increases in stiffness do not lead to longer jumps.

Leg stiffness can be enhanced by weight training and plyometric drills, power combination training and jumping itself. However, from a more technical perspective, researchers have advocated increasing the touch down velocity of the take-off leg to improve jumping distance. This is something that is also recommended, by George Dintimen(6), one of the world’s leading speed coaches. He argues that the faster a plyometric drill is performed (the long jump take-off is a plyometric movement) the greater, everything else being equal, will be the power transference into the jump. Using another analogy, the harder a ball is thrown against a wall the further and quicker it will fly back.

Thus, the faster the foot makes contact with the ground during jumping and running movements, the quicker the reaction will be. However, despite this, athlete and coach need to realise that certain jumping movements require more ground contact time than others (see table 2, opposite). If a high jumper attempted to use the same amount of approach speed as a long jumper, then optimum vertical lift would be sacrificed, as there would not be enough ground contact time to generate vertical lift. It is important that these take-off times are replicated in training, as well as the foot-strike position, and that free limb movements are optimised (as outlined above) for maximum jumping power.

Training to improve jumping ability

How can athletes utilise these findings to enhance their own training performance? As indicated, plyometric drills are the main weapon in the training armoury when it comes to enhancing jump ability. Here’s how to get the most out of them:

  • Plyometric exercises must replicate the movement patterns and speed of movement of the jumping activity as closely as possible.
  • Athletes should be fresh and rested when performing plyometric exercises, especially if they perform in immediate anaerobic pathway activities such as long and high jump and the gymnastic vault.
  • For sports involving fatigue, where jumping is required, such as football and rugby, quality jumping power should be developed, in ways similar to immediate anaerobic pathway athletes, but also in separate workouts, under conditions of fatigue. Exercises should also be performed on the surface that the player will normally encounter, ie in the case of a field sports player, soft to hard turf.
  • For field sports (as for immediate anaerobic activities) the mechanics of the jumping skill must be optimised. For example, footballers must be made aware of the importance of using their free limbs to aid height and distance. However, due to the nature of these sports, perfect technique will not always be possible. To this end practices should be employed that work on balance, kinaesthetic awareness and proprioception. These will maximise jumping potential and reduce the chances of injury, as the player is able to better control the position of their body in space, their proximity to other players and their landing.
  • Power combination training that combines weights and plyometrics in the same workouts should be utilised throughout the training period. Research indicates that both exercise modes affect the other in a way that enhances the power generation of fast-twitch muscle fibre.

John Shepherd MA is a specialist health, sport and fitness writer and a former international long jumper

References
1. J Sports Med Phys Fitness 1999 Dec; 39(4):285-93
2. J Electromyogr Kinesiol 2001 Oct; 11(5):365-72
3. Ergonomics 2000 Oct; 43(10):1622-36
4. Med Sci Sports Exerc 1999 May; 31 (5) 708-16
5. J Biomech 1999 Dec; 32(12):1259-67
6. Dintimen G, Sports Speed (third edition) Human Kinetics 2002
7. J Sports Med Phys Fitness 2003 Mar; 42(1): 21-7

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