PAP theory & Application Flashcards
What is post-activation potentiation (PAP)?
PAP is a phenomenon where muscular performance characteristics are acutely enhanced as a result of their contractile history. It is induced by a voluntary conditioning contraction (CC), typically at maximal or near-maximal intensity. The underlying principle is that heavy loading prior to explosive activity induces a high degree of CNS stimulation resulting in greater motor unit recruitment
What are the proposed mechanisms underlying PAP?
The proposed mechanisms include:
◦ Phosphorylation of myosin regulatory light chains (RLC).
◦ Increased recruitment of higher-order motor units.
◦ A possible change in pennation angle
How does RLC phosphorylation contribute to PAP?
RLC phosphorylation is thought to potentiate subsequent contractions by altering the structure of the myosin head, moving it away from its thick filament backbone. It also renders the actin-myosin interaction more sensitive to myoplasmic Ca2+.
How does increased recruitment of higher-order motor units contribute to PAP?
An induced tetanic isometric contraction elevates the transmittance of excitation potentials across synaptic junctions at the spinal cord, increasing post-synaptic potentials for the same pre-synaptic potential during subsequent activity
What is the H-reflex and how is it related to PAP?
The H-wave (H-reflex) is recorded at the muscle fibers using electromyography, and is the result of an afferent neural volley in response to single-pulse sub-maximal stimulation of the relevant nerve bundle. An increase in H-wave following a CC may represent a decrease in transmitter failure at synaptic junctions, and a subsequent increase in higher order motoneuron recruitment
How might changes in pennation angle contribute to PAP?
A significant decrease in pennation angle has been observed 3–6 minutes after MVCs. This change would be equivalent to a small increase in force transmission to the tendons, but conditioning contractions are also likely to increase connective tissue/tendon compliance, which may counter any increase in force transmission caused by a decrease in pennation angle
What factors affect the PAP-fatigue relationship?
Several variables affect the PAP-fatigue relationship, including:
◦ CC volume and intensity.
◦ Recovery period following the CC.
◦ Type of CC.
◦ Type of subsequent activity.
◦ Subject characteristics
CC= conditioning contraction
How does conditioning contraction (CC) volume affect PAP?
PAP develops quicker than fatigue and may be utilized immediately after a relatively low CC volume. As CC volume increases, so does fatigue, requiring a recovery period before PAP is realized.
How do isometric and dynamic conditioning contractions differ in their effects?
Preliminary evidence suggests that isometric CCs may induce greater central fatigue but are more likely to activate the peripheral mechanisms of PAP. Dynamic CCs may induce greater peripheral fatigue but are possibly more likely to activate the central mechanisms of PAP.
What subject characteristics influence PAP?
Subject characteristics that may affect PAP include:
◦ Muscular strength.
◦ Fibre-type distribution.
◦ Training level.
◦ Power-strength ratio
How does muscular strength relate to PAP?
Stronger individuals have demonstrated a greater PAP response. This may be associated with a higher percentage of type II muscle fibers and a greater number of higher-order motor units
How does fiber-type distribution relate to PAP?
Subjects with predominantly fast-twitch (type II) muscle fibers show greater twitch tension potentiation during the early stages of a fatigue protocol but also have a greater decrease in both twitch Pt and MVC Pt during the later stages of the fatigue protocol
What are some arguments against using PAP?
Arguments against using PAP include:
◦ Limited research on humans.
◦ Combined training may lead to lesser results.
◦ Impracticality due to equipment needs and continuous athlete testing.
◦ Dynamic warm-ups may be equal to or better than PAP.
◦ Heterogeneity of response and challenges in identifying windows of opportunity.
What is the specificity principle in relation to PAP?
The specificity principle states that the movements used in conditioning contractions should closely resemble the movements in the subsequent explosive activity, engaging the same muscles in a similar fashion to maximize transfer of potentiation
How does training level affect PAP?
Individuals with a higher training age, particularly in strength and power, elicit better PAP responses. This suggests that PAP may not be as beneficial for beginners
What is the power-strength ratio, and how does it relate to PAP?
The power-strength ratio reflects an individual’s ability to convert strength into power. Individuals who are already good at converting strength to power may not see as much gain from PAP compared to those with high strength but a relatively lower power output
What is the role of fatigue in PAP?
Fatigue can mask the effects of PAP, especially with higher conditioning contraction volumes. The balance between PAP and fatigue determines whether subsequent performance is enhanced, diminished, or unchanged.
What are the potential benefits of PAP for endurance athletes?
In endurance athletes, PAP may improve the economy of movement, such as running or rowing economy, rather than increasing explosive power. The conditioning contractions for endurance athletes typically involve lower intensities and volumes
What are the limitations of current PAP research?
Limitations include:
◦ Limited research on humans, especially elite athletes.
◦ Heterogeneity of response among individuals.
◦ Difficulty in standardizing methodologies and protocols.
◦ Challenges in measuring and accounting for fatigue
How can PAP be incorporated into training?
PAP can be incorporated into training through complex or contrast training methods, where a heavy strength exercise is followed by a power exercise. This may increase workout density and work capacity.
What is the H-reflex?
The H-reflex is a neurological reflex that is a response directly from the spinal cord, involving the alpha motor neuron. After sufficient recovery, this reflex increases
What are the practical implications of PAP?
Practical implications include:
◦ PAP may enhance mechanical power, leading to improved performance or training stimulus in explosive sports.
◦ PAP can be used in power-training routines to enhance the training stimulus of plyometric exercises.
◦ PAP might be better than conventional warm-up techniques for explosive sports.
◦ There are practical challenges in applying PAP in competition, such as equipment needs and timing recovery
What is the difference between PAP and PTP?
The difference between PAP and PTP is defined by the nature of the conditioning contraction. PTP is induced by an involuntary tetanic contraction, and PAP is induced by a voluntary contraction performed typically at a maximal or near-maximal intensity
How does PAP affect mechanical power?
PAP could benefit the performance of explosive sports activities by increasing rate of force development (RFD) and thus mechanical power
What is the effect of isometric MVCs on subsequent voluntary motoneuron recruitment?
Studies using the interpolated twitch technique (ITT) have reported a decrease in voluntary muscle activation following 10-second MVCs. This contrasts with the proposed mechanism of PAP but may demonstrate the dominance of central fatigue
How does conditioning contraction type affect the mechanisms of PAP and fatigue?
Isometric CCs may induce greater central fatigue but are more likely to activate the peripheral mechanisms of PAP, whereas dynamic CCs may induce greater peripheral fatigue but are possibly more likely to activate the central mechanisms of PAP
How does the type of subsequent activity influence PAP effects?
A specific CC may not have the same effect on different explosive activities. It’s important to closely match the kinematics of the CC to those of the subsequent explosive activity.
