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Post-activation Potentiation
Post-activation potentiation is a method to improve short-term explosive power
Introduction
Athletes and coaches are continually seeking innovative methods to improve athletic performance. Athletes who engage in highly explosive sports, such as sprinting, throwing and jump sports, may benefit from including specific warm-ups that can increase performance and reduce injury risk. Post-activation potentiation protocols utilise efforts at a high % of One Repetition Maximum (1RM) load in a resistance exercise in the immediate pre-performance warm-up with the explicit aim of gaining an acute increase in subsequent performance.
What is post-activation potentiation?
Post-activation potentiation (PAP) represents an acute improvement in muscle function. The improvement in function is seen as a short-term effect on explosive performance performed subsequent to a heavily-weighted resistance exercise such as a power clean, jump squat, squat or isometric squat (squat held at 90°). After the pre-performance resistance exercises, a rest period is allowed for this potentiation to act. The rest period allows for the fatiguing effects of the resistance exercise to subside, and when this occurs, the potentiation effects on the muscle and performance can become evident. Typically the load used as resistance is between 30% - 100% of 1RM or 100% of multiple RM. This represents a wide variance in the level of load used, for all loading single or double efforts are used. For loads at lower percentage of a 1RM, 30-60%, speed of movement must be emphasised and maximised for each effort. Increasing the number of repetitions used may only serve to induce excessive fatigue delaying the emergence of the PAP effect.
The performance enhancement by potentiation protocols comes about by an increase in the firing rate of contractile proteins in muscle fibres. This increased firing rate happens as a response to the prior high loading in the resistance activity. The increased contraction rate is initiated in anticipation of a similar load stimulus being received; in turn a greater number of motor units are activated and are recruited for movement with greater synchronicity. The athlete must undertake resistance exercises in which they can withstand high loads and that are comparable somewhat to the activity we seek to enhance, i.e. jump squat with vertical jump height improvement. Potentiation allows sufficient force to be generated within the muscle to activate a greater number of motor units to improve performance.
What factors affect post-activation training?
PAP-mediated performance adaptations are thought to be brought about through either a combination of or a predominance of one of the following two factors:
Increased rate of myosin head reattachment post-power stroke.
- In simple terms this means that the moving parts within the muscle cell move faster and more often. This allows for a greater work action by the moving units in skeletal muscle resulting in greater performance.
Central nervous system facilitation through increased utilisation of closed-feedback chains through the spinal cord.
- In response to increased load, your nervous system takes out the necessity to perceive the load in order to activate greater number of motor units in the subsequent actions. For the same level of effort, you get greater muscle activation.
The level of success of a postactivation potentiation bout is dependent on a number of factors:
The training status of the individuals
- Experienced v Novice
The competitive level of the athletes
- Elite v Recreational
The recovery duration post-high force exercise
- 15 seconds – 20 minutes
The dynamic of the activity
- High speed dynamic
- Low speed dynamic
- Isometric
The test activity
- Jump v Sprint
Training Status
Athletes with greater resistance training experience tend to show a greater response to PAP bouts than athletes of lesser experience. Experienced athletes also respond more positively than novice athletes to higher percentage loads in PAP sessions, this may be due to a greater activation of the musculature involved due to greater experience of resistance training. A secondary cause for this difference may be the greater fatiguing effects of a high percentage load PAP intervention on the less experience athlete. In addition, it is likely that the greater demand at elite level competition for high speed, high force generation may assist elite level athletes to a gain greater positive effect from PAP training. Individuals who demonstrate a greater ability for high speed, high strength force generation are therefore potentially more suited to PAP training.
From PAP to performance, the role of recovery
Following a bout of potentiation training, the duration of recovery allowed between the potentiation exercise and the performance exercise is the critical factor in allowing any positive improvements to become evident. Using weighted exercises unavoidably induces fatigue, the amount of recovery afforded between potentiation exercise and performance test will influence the extent to which fatigue will affect the subsequent performance. Fatigue predominates in the initial period post exercise; the recovery window will allow fatigue to dissipate and potentiation to effect to proceed. The amount of recovery required will be influenced by the training status and competitive level of the athlete.
Other Factors
The remaining factors which influence PAP success are the exercise type (high force >85% 1RM / high speed 30-60%1RM & max velocity / isometric) and the activity type (jump v sprint). The evidence at present is unclear on the optimal activity to bring about acute positive changes in muscle performance. This is due to the high variability in the effect of an exercise modality coupled with the previously outlined influences on PAP success. The current available evidence appears to support the use of high force (>85% 1RM) exercise as potentiating activity in sprinting. The effectiveness of high force loads in achieving jumping improvements is less clear, however some evidence exists to support the use of loaded dynamic movements (jumps with weighted vest/ power clean / jump squat) to promote favourable jump performances. However, the benefit association between high force activities at >85% 1RM completed slowly and improvements in high velocity unloaded movements highlights a disparity that may not create optimal conditions for PAP. A more beneficial PAP intervention may be brought about by linking the more closely the PAP initiating exercise to the subsequent performance activity but at present information is not available on the effect of resisted performances exercises (i.e. resisted sprint prior to timed sprint) as an initiator of PAP.
Conclusions
In summary, post-activation potentiation is a method to improve short-term explosive power. It may be included as a warm-up activity for experienced resistance-trained athletes competing at elite levels. The duration of recovery allowed between the intervention resistance exercise and the performance measure will affect the fatigue-potentiation interaction. The time required for adequate recovery will be influenced by training history and should be sufficient to allow the PAP affect to develop. The type of subsequent exercise/performance being measured will influence the selection of the exercise type for PAP; jumping activities may be influenced by loaded dynamic activities and sprint activities may be influenced by activities using >85% of 1RM.