THE POWER OF PLYOMETRICS
Commonwealth Champion Powerlifter – @DomCadden
For years, plyometric training was largely shunned at all levels below the elite athletes as health industry/media spread fear campaigns against ‘ballistic’ and high-impact’ movements. Today we know that this type of training can increase athletic performance in both endurance athletes and those doing strength/power sports. So what are you waiting for? Jump to it!
WHAT IS PLYOMETRIC TRAINING?
Plyometric training came to us via East Germany’s state sports trainers in the 1970s. It’s based on scientific evidence that shows that a concentric (shortening) muscular contraction is much stronger if it immediately follows an eccentric (lengthening) contraction of the same muscle – like the bending of the knees immediately prior to jumping, which uses stretch reflexes in the quads, hams and calf muscles.
At speed, this action prompts the stretch or ‘myotactic’ reflex of muscle and improves power. It’s a bit like stretching out a coiled spring and then letting it go to release great energy, if only for a split second. With regular practice, muscle fibre will be able to store more elastic energy as the nervous system becomes conditioned to react more quickly to the stretch-shortening cycle.
This type of training typically includes hops, jumps, bounds and throws.
WHAT’S IT GOOD FOR?
By increasing power output, plyometrics can help with many motions used in sport –vertical jumps, sprint acceleration, punching, throwing and more.
In scientific lingo, researchers say plyometric training has the ability to improve performance by inducing “greater motor-unit recruitment, enhanced reflex potentiation and enhanced elasticity of the muscleand related connective tissue”. (Vissing et al., 2008).
Even endurance runners can benefit, as many plyometric drills build foot, ankle and calf strength to enhance speed and agility by conditioning the lower limbs to accept greater eccentric strength. This reduces injury potential by increasing ‘rigidity’ and reducing the force of impact on the joints. Consider this: running typically exerts a force of three times body weight as the foot hits the ground. In plyometric training, it’s common for this force to be up to seven times bodyweight. In long distance running, injuries frequently occur at the soft tissue around joints (e.g. knees) or at the bones themselves (e.g. feet). Graduated plyometric training strengthens soft tissue around joints to protect them and the American College of Sports Medicine states that regular plyometric training may also help to strengthen bone.
PLYOMETRIC TRAINING ALSO HELPS:
- reduce the risk of anterior cruciate ligament (ACL) injury via proper nerve/muscle control of the knee, especially in younger female basketball, netball and soccer players, who have a risk of 2-8 times higher than that of their male counterparts
- sprinting - at their quickest, weight training lifts take about 0.5-0.7 seconds, but a sprinter's foot may only be in contact with the ground for 0.084 seconds (about 0.2 seconds at moderate pace). A plyometric drill allows for similar ground contact/force production times
- children and adolescents develop power in a safe manner, according to the American College of Sports Medicine
- any sport where a plyometric drill can mimic the motion better than typical weights exercises.
CHOOSE YOUR EXERCISES
Websites such as EXRX.net describes a range of plyometric exercises for you to choose from. Here are some points to remember:
- Pick movements that imitate (even exaggerate) the movements in your sport
- Exercises with double feet (for jumps, bounds) will be less stressful than single-leg exercises
- High-intensity, advanced drills include those that start with a run-up before jumping or bounding, or exercises such as depth jumps, which involve repeated jumping down from boxes as high as 42 inches (just over one metre) and back up onto boxes
- Early in a training cycle, endurance runners could set up a circuit style sequence - high reps, multiple sets and short recoveries with low-level power exercises such as double-leg hops (in a straight line or zig-zag).
HOW MUCH SHOULD YOU DO?
In plyometric training, intensity is the key and it’s important not to overdo it – this will ensure optimum firing of the stretch/reflex.
The recommended volume is often measured in terms of ‘contacts’ (e.g. for jumps and hops that’s the number of times the feet hit the ground).
As a guide, a beginner in pre-season training could perform 60-100 foot contacts of low intensity exercises (jumps on the spot or from standing start) in a single workout. Intermediate athletes can do 100-150 foot contacts of low intensity exercises and another 100 of moderate intensity in another workout. Advanced athletes might get up to 150-200 foot contacts of low-to-moderate intensity exercises in this cycle.
The more dynamic the move (e.g. running starts, one-legged drills, depth jumps) and the greater power generated, the less foot contacts you should do and the longer the recovery time. As training phases progress, the number of foot contacts should reduce in order to maintain power and speed.
A prominent researcher in the field, Prof. Yuri Verhoshansky, recommended that for bounding (a good drill for runners), do 4 x 15m of bounds or no more than 5-10 bounds per set, with no more than 50-75 ground contacts in a session. Reduce the number of bounds if you have a running start or finish.
Rest 1-2 minutes between and pause at least 15-30 seconds between successive depth jumps and sequences of hopping or bounding sequences. Two to three sessions per week are enough.
Beginners should start with easy and safe ground-level jump-offs onto padded surfaces such as grass or a gym mat on a wood gym floor.
For your own safety and to maximise benefits, you should stop a set or alter your exercise as soon as you cannot hold correct form or maintain speed.
You should aim to land from toe to heel when you land from a vertical jump, using the entire foot as a rocker to distribute the impact over a greater surface area, and avoid excessive side-to-side motion at the knee. Think “land light as a feather”. For consecutive jumps/hops or depth jumps, treat the ground or floor like hot coals – aim to keep a firm ankle and foot so you minimise contact time with the ground.
If you currently have joint or bone issues, then you’re probably not a good candidate for plyometric training.
Frequent sessions are likely to do more harm than good and hold back your sport performance. Even if you’re a seasoned athlete, any training routine that builds strength through explosive movement is going to come with some increased risk of injury. Plyometrics cause severe structural disruption in the muscle fibres, so at least 48 hours should be allowed between two intense plyometric sessions.