Related Experiment Video
Updated: Jun 25, 2026

Assessment of Neuromuscular Function Using Percutaneous Electrical Nerve Stimulation
Published on: September 13, 2015
Postactivation potentiation of force is independent of h-reflex excitability
Matthew J Hodgson1, David Docherty, E Paul Zehr
1Rehabilitation Neuroscience Laboratory and the School of Physical Education, University of Victoria, Victoria, BC.
Unlabelled:
The contractile history of muscle can potentiate electrically evoked force production. A link to voluntary force production, related in part to an increase in reflex excitability, has been suggested.
Purpose:
Our purpose was to quantify the effect of postactivation potentiation on voluntary force production and spinal H-reflex excitability during explosive plantar flexion actions.
Methods:
Plantar flexor twitch torque, soleus H-reflex amplitudes, and the rate of force development of explosive plantar flexion were measured before and after 4 separate conditioning trials (3 x 5 s maximal contractions).
Results:
Twitch torque and rate of force production during voluntary explosive plantar flexion were significantly increased (P < .05) while H-reflex amplitudes remained unchanged. Although twitch torque was significantly higher after conditioning, leading to a small increase in the rate of voluntary force production, this was unrelated to changes in reflex excitability.
Conclusion:
We conclude that postactivation potentiation may result in a minor increase in the rate of voluntary isometric force production that is unrelated to neural excitability.
Related Concept Videos
Long-term Potentiation
Long-term Potentiation
Hebbian LTP
LTP can occur when presynaptic neurons...
Motor Unit Stimulation
The latent period of contraction marks the onset of excitation-contraction coupling, when the action potential propagates across the sarcolemma, preparing the muscle fibers for contraction. As the fibers enter the contraction phase, the...
Relaxation of Skeletal Muscles
When an action potential reaches the axon terminal, it depolarizes the membrane and opens voltage-gated sodium channels. Sodium ions enter the cell, further depolarizing the presynaptic membrane. This depolarization causes voltage-gated calcium channels to open.
Muscle Stimulation Frequency
Wave summation
At low firing rates, motor neurons induce individual twitch contractions in muscle fibers. These twitches...
Generation of Action Potential in Skeletal Muscles
Like neurons, muscle cells are also regarded as excitable due to their capacity to change in response to stimuli, primarily due to voltage-gated ion channels embedded in their plasma membranes, which get activated by alterations in the cell's...

