Figure 4
Power is closely related to two components of fitness: strength and speed. Power is effectively the product of strength and speed (Faigenbaum, 2017) and is the ability to execute strong explosive movement at speed. As such, speed, strength and power are often jointly identified in needs analyses as key components of fitness in certain sports and/or activities (such as rugby, weightlifting, sprinting or hammer-throwing).
In this section you will primarily be considering two power training methods (plyometric training and weight training) and the science behind them. Plyometric training refers to explosive jump training that involves fast, powerful movements that are preceded by a stretch or countermovement (Potach and Chu, 2016). Before you consider these power training methods in detail you need to look at the physiology and biomechanics involved.
Figure 5
When a muscle is stretched rapidly, the neuromuscular system responds by initiating a concentric muscle contraction to prevent the muscle from being stretched too far and becoming damaged. This is known as the stretch-reflex system. In plyometrics, this means that if a rapid eccentric loading phase is performed before a concentric contraction, a greater and more powerful concentric muscle action will occur. This ‘pre-stretch’ action is known as the stretch shortening cycle and is explained further in Activity 4.
Allow 40 minutes for this activity
Watch Video 4, on the stretch-shortening cycle, at the link below. Focus on the section between the start and 02:55. Once you’ve watched Video 4, do the related tasks below.
Video 4: The stretch-shortening cycle
1. Use the drop-down menus to select the correct missing word.
Interactive content is not available in this format.
2. Put the three phases of the stretch-shortening cycle in the order they are performed.
First
Second
Third
Eccentric
Amortisation
Concentric
Now that you have an understanding of how plyometric training works, in the next section you will investigate some examples of plyometric training.
Figure 6
Various studies have found plyometric training to be effective in developing power and improving performance (Stojanović et al., 2017). A wide range of plyometric exercises may be employed to develop power. Potach and Chu (2016) divide these into lower-body, upper-body and trunk exercises. The choice of exercises should depend on various factors, including the unique requirements of the individual (needs analysis), their age and fitness levels. You will consider some examples of plyometric exercises in Activity 5.
Allow 30 minutes for this activity
Watch Video 5, in which a range of plyometric exercises are demonstrated. Then select one exercise that you think would be most appropriate to use with a 200m sprinter and explain why you selected this particular exercise.
Video content is not available in this format.
Video 5 Plyometric exercises
Plyometric training provides an effective way to develop functional power and enables the strength and conditioning coach to prescribe functional exercises for the athlete which are specific to that athlete’s sport. In the early training of plyometrics, developing proper technique and balance must be prioritised to minimise the injury risk of the high intensity exercise. In the next section you will look at another method of developing power: weight training.
Figure 7
In strength and conditioning, it is important to prescribe the correct intensity/load (i.e. % of repetition maximum (RM), number of repetitions, sets and amount of rest in relation to the training goal to gain maximum results). Table 2 shows that for power, high load and relatively few repetitions are recommended.
Table 2 Training principle recommendations for training goals
Training goal |
Load (% of 1RM) |
Repetitions | Sets | Rest | |
---|---|---|---|---|---|
Maximal strength | ≥ 85 | ≤ 6 | 2–6 | 2–5 minutes | |
Power | single-effort event | 80–90 | 1–2 | 3–5 | 2–5 minutes |
multiple-effort event | 75–85 | 3–5 | |||
Hypertrophy | 67–85 | 6–12 | 3–6 | 30–90 seconds | |
Muscular endurance | ≤ 67 | ≥ 12 | 2–3 | ≤ 30 seconds |
Source: Sheppard and Triplett (2016)
A single-effort event is where one maximum-power effort is required (i.e. shot put, high jump, power lifting). A multiple-effort event is one where repeated maximum-power efforts are required (i.e. rugby, volleyball).
For power, the type of exercise is also important to achieve training goals. In this section you will consider some examples of weight-lifting exercises that are suitable for developing power. As you would expect, given the definition of power, such exercises involve fast, explosive movements; you will investigate some of these in Activity 6.
Allow 10 minutes for this activity
Watch Video 6 in which you will see several weight-lifting exercises designed to develop power. Which exercises would be most appropriate for developing explosive leg power? Watch from 02:32 (‘Once you have a basis of strength …’) to 03:35 (‘… high-velocity power output movement’).