The Effect of Stretching Intensity on Pain Sensitivity

The primary objective of this study is to determine the immediate efficiency of stretching intensity on regional and distant pain sensitivity in healthy subjects. It is hypothesized that the analgesic effect of stretching may be linked with the intensity of stretching in a dose-response relationship.

This was a randomized, repeated-measures cross-over study. The interventions consist of two different stretching protocols (e.g., stretching to the point of discomfort and stretching to the point of pain). Subjects were randomized to one of two groups (pain first or discomfort first). Both groups underwent a static stretch protocol consisting of four bouts of thirty-second constant-angle static stretching of the knee flexors with a 20-second rest period between bouts. Subjects were instructed to keep the limb relaxed as the lower leg was passively moved towards extension to the point of discomfort and the point of pain.

Participants were blinded to the results of all measurements and naïve to research hypotheses. The investigator was blinded to the results of all measurements.

The participants are assigned to four bouts of static stretching of the right knee flexors with a 20-second rest period between bouts 20 to the point of pain.

The participants are assigned to four bouts of static stretching of the right knee flexors with a 20-second rest period between bouts 20 to the point of discomfort.

The participants are assigned to four bouts of static stretching of the right knee flexors with a 20-second rest period between bouts 20 to the point of discomfort and to the point of pain.

Pressure pain thresholds were measured as a baseline just prior to the induction of stretching to the point of pain and stretching to the point of discomfort

Passively induced knee extension range of motion was measured using the Biodex system 4 pro isokinetic dynamometer

Passive knee extension range of motion was measured as a baseline just prior to the induction of stretching to the point of pain and stretching to the point of discomfort

Passively induced knee extension range of motion was measured using the Biodex system 4 pro isokinetic dynamometer

Passive resistive torque was measured as a baseline just prior to the induction of stretching to the point of pain and stretching to the point of discomfort

Inclusion Criteria: Healthy men and women aged 18-55 years are recruited. As part of the screening, volunteers will also be asked to indicate known medical issues or diseases. Exclusion Criteria: Participants are included if they have no known medical conditions such as; cognitive impairments, neurological, orthopaedic, or neuromuscular problems that might affect the somatosensory system or preclude stretching exercises or range of motion testing at the knee.