Power training enables an athlete to apply the greatest amount of their maximal strength in the shortest period of time.
This is crucial for many sports men and women who will rarely be required nor have the time to produce maximal forces.
Most athletic activities involve far faster movements and far higher power outputs than are found in maximal strength exercises (4,5). An athlete can be exceptionally strong but lack significant explosive power if they are unable to apply their strength rapidly.
This article outlines the various methods of power training, their parameters and how they can be used to convert maximal strength into sport-specific power. But before examining how power training should fit into the overall strength program, it's important to have a basic understanding of the relationship between the force of movement and the velocity of movement...
Power is intimately related to force and time, which can be expressed in the simple formula:
Traditional strength training typically alters the top half of this equation - increasing the ability to apply a maximum amount of force. But for power to be maximized the time component must also be altered. This is the aim of power training - to reduce the amount of time it takes to apply a set amount of force.
Maximum force production occurs when the speed of movement is very low (i.e. performing a one repetition maximum lift) or zero such as performing a static or isometric exercise.
Conversely, as the speed of movement increases, force decreases and at very high speeds force production is very low. Between these two extremes is an optimal point for power development. In fact, maximal power occurs at intermediate velocities when lifting moderate loads (6,7). Peak power output is typically seen when loads of 30% one repetition maximum (1-RM) are used (6,8).
This relationship between force and velocity and its affect on power explains why an athlete can be exceptionally strong but lack significant power if they are unable to apply much of their strength over a short period of time.
Assuming an athlete has maximized his or her ability to apply force (through maximal strength training), it would be beneficial if they could train to increase the rate of force production. Increasing the rate at which strength can be generated positively alters the time aspect of the power equation above.
The goal of power training is to increase the rate of force production and there are several methods that have been devised to do this...
Below are four methods of power training. A prerequisite to starting one of these routines is the development of a solid base of functional strength. Power training, particularly plyometrics and ballistics, becomes less effective and the risk of injury is increased if a phase of anatomical adaptation has not already been completed.
Heavy Strength Training
Strength training alone can increase explosive power by positively affecting the top half of the power equation or the peak force production (9,10,11). Most athletic movements also start from a stationary position and it is this early phase of moving a resistance (be it a medicine ball or bodyweight) that requires the most effort. Therefore the greater an athlete's strength is, the more explosive this initial phase of motion will be. However, once this initial inertia has been overcome less force and more speed is required to continue the movement and heavy strength training becomes less suitable.
Additionally, lifting weights of 70-100% 1-RM has also been shown to reduce the rate of force production which is counter-productive to power development (12). This may explain why in strength trained individuals heavy resistance training is less effective at increasing vertical jump performance compared to ballistics or plyometrics for example (11,13,14).
For an athlete who already has a solid base of strength training (+6 months) gains in power are minimal with further weight training (15,16). Of course, untrained individuals can significantly improve their power with weight training (15,17) and this is a safer and more favorable mode of training than some of the advanced techniques that follow.
Explosive Strength Training
Once a plateau in strength has been reached, more sport-specific types of power training are required. One of these training methods is a variation of traditional resistance training. As mentioned earlier, maximal power production occurs when moderate loads of about 30% 1-RM are used.
Completing traditional weight lifting exercises as fast as possible with relatively light loads produces in theory, the greatest power output. Unfortunately there is a problem with this approach...
Lifting a bar rapidly loaded with 30% 1-RM is difficult to execute, particularly in the final phase of the movement. The athlete must decelerate and stop the bar in order to keep it under control (18,19). This deceleration activates the antagonist muscles negatively affecting power output and hinders the required adaptations (11,20).
Ballistics and plyometrics avoid this problem, as there is no deceleration. The athlete is free to jump as high as possible or throw an object as far as possible without restricting the movement.
If free weights exercises are used for power training, loads of 75-85% are recommended (1,8,11) for sets of 3-5 repetitions. The parameters for explosive strength training can be seen in the table below:
For single power efforts such as the throwing events in athletics, a higher load (80-90% 1-RM) can be used for a smaller number of repetitions (1-2). A multiple power effort sport includes sprinting,team sports or any event that requires repeated efforts.
Sets are not performed to exhaustion as the quality and speed of each lift is the most important factor. Rest intervals are also kept high for the same reason.
During a ballistic action, the force far outweighs the resistance so movement is of a high velocity. The resistance is accelerated and projected. Examples include a medicine ball throw and a jump squat. The aim is to reach peak acceleration at the moment of release projecting the object or body as far as possible.
While there is no definitive guidelines for the resistance used with ballistics, Fleck and Kraemer (3) suggest a load of 30-35% 1-RM should be used for exercises that include free weights such as jump squats. For many ballistic exercises the weight of the objects themselves dictate the load i.e. medicine balls ranging from 2-6kg (4.4-13lbs) and kettlebells ranging from 10-32kg (22-70lbs).
Parameters for ballistic power training are summarized in the table below:
Repetitions can be reasonably high as the nature of some exercises means there can be up to 20 seconds between efforts - for example when a medicine ball has to be retrieved. A set should stop however, the moment the speed and quality of movement can no longer be maintained.
For exercises such as jump squats that use 30% 1-RM loads, Fleck and Kraemer (3) recommend up to 5 sets of 3 repetitions with 3 minutes rest between sets.
Ballistics can place considerable eccentric forces on joints, ligaments and tendons when landing from a jump squat for example. Athletes should always progress gradually from unloaded to loaded exercises and must not be fatigued before starting a ballistic power training session.
Plyometric drills involve a quick, powerful movement using a pre-stretch or counter-movement that involves the stretch shortening cycle (1). Classical plyometric exercises include various types of jump training and upper body drills using medicine balls.
Plyometrics is a suitable form of power training for many team and individual sports. While many might see it simply as jumping up and down, there are important guidelines and program design protocols that need to be followed if plyometrics is to be as safe and effective as possible. For this reason, and due to its popularity plyometrics has its own section of the website...
For full plyometric guidelines and sample sessions see the plyometric training section of the website.
The type of power training employed must be the most specific to the sport or event. Olympic lifts, such as power cleans, may be suitable for sports such as football and rugby. Some plyometric exercises are suitable for soccer and hockey. Ballistic exercises with medicine balls fit well with basketball and volleyball.
But many sports would benefit from a combination of power training methods. Take basketball for example - explosive strength training such as power cleans, plyometric exercises such as depth jumps and ballistics such as jump squats and overhead medicine ball throws would all be suitable choices.
Interestingly, a study measuring the effects of three types of power training found that all of them increased vertical jump performance. However, while traditional weight training lead to a 5% increase and plyometrics a 10% increase, the most effective was ballistic jump squats, which lead to an 18% improvement in jump height (11). This confirmed the findings of a similar earlier study (14).
Does this mean ballistics is superior to other forms of power training? Not necessarily. In this case it may be that jump squats was the most specific to the performance outcome.