Objectives: To compare knee flexors and extensors muscle strength, total work, and power between females with fibromyalgia (FM) and matched healthy controls.
Methods: This is the first study to measure knee muscle power and total work in females with FM. Thirty-one females with FM and thirty-one healthy females completed isokinetic testing of knee flexors and extensors of their dominant leg using a Cybex Norm Isokinetic Dynamometer. Two knee muscle groups (flexors and extensors) at two angular velocities (607sec and 1807sec) were tested for both groups. Both muscle groups were assessed continuously using five reciprocal concentric-concentric cycles, followed by five eccentric-eccentric cycles.
Results:Females with FM exhibited significant decreases in voluntary muscle strength ranging from 18%-24% and average power ranging from 25%-30%, more pronounced for knee flexors than knee extensors. The strength and power deficits were not uniform during all test arrangements: 1) Maximum eccentric muscle strength for knee flexors and extensors at an angular velocity of 60 /sec in females with FM was reduced compared to the control group (p = .005 and .007, respectively), 2) Maximum concentric muscle strength for knee flexors at an angular velocity of 180 /sec in females with FM was reduced compared to the control group (p = .002), and 3) Average power for knee flexors at an angular velocity of 607sec for eccentric muscle action and 1807sec for concentric muscle action in females with FM was reduced compared to the control group (p =.006 and .001, respectively). No differences in total work at the two different velocities for the two muscle actions were found.
Conclusion: We found decreased knee muscle strength and power in females with FM compared to healthy females. This may be due to muscle soreness from unhealed microtraumas, slow deformation of collagen and periarticular connective tissue of the knee joint, hypoxia, or decreased content of high energy metabolites.
","abstract_html":"<p><strong>Objectives:</strong> To compare knee flexors and extensors muscle strength, total work, and power between females with fibromyalgia (FM) and matched healthy controls.</p> <p><strong>Methods:</strong> This is the first study to measure knee muscle power and total work in females with FM. Thirty-one females with FM and thirty-one healthy females completed isokinetic testing of knee flexors and extensors of their dominant leg using a Cybex Norm Isokinetic Dynamometer. Two knee muscle groups (flexors and extensors) at two angular velocities (607sec and 1807sec) were tested for both groups. Both muscle groups were assessed continuously using five reciprocal concentric-concentric cycles, followed by five eccentric-eccentric cycles.</p> <p><strong>Results:</strong>Females with FM exhibited significant decreases in voluntary muscle strength ranging from 18%-24% and average power ranging from 25%-30%, more pronounced for knee flexors than knee extensors. The strength and power deficits were not uniform during all test arrangements: 1) Maximum eccentric muscle strength for knee flexors and extensors at an angular velocity of 60 /sec in females with FM was reduced compared to the control group (p = .005 and .007, respectively), 2) Maximum concentric muscle strength for knee flexors at an angular velocity of 180 /sec in females with FM was reduced compared to the control group (p = .002), and 3) Average power for knee flexors at an angular velocity of 607sec for eccentric muscle action and 1807sec for concentric muscle action in females with FM was reduced compared to the control group (p =.006 and .001, respectively). No differences in total work at the two different velocities for the two muscle actions were found.</p> <p><strong>Conclusion:</strong> We found decreased knee muscle strength and power in females with FM compared to healthy females. This may be due to muscle soreness from unhealed microtraumas, slow deformation of collagen and periarticular connective tissue of the knee joint, hypoxia, or decreased content of high energy metabolites.</p>","abstract_has_math":false,"creators":["Shafiee, Flora F."],"institution":null,"degree_name":"Doctor of Physical Therapy (DPT)","degree_level":"Dissertation","degree_discipline":"Physical Therapy Sciences","degree_department":null,"school":null,"contributors":["Grenith J. Zimmerman","Keith K. Colburn","Everett B. Lohman III","Bradford D. Martin","James M. Syms"],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2005,"date_issued":"2005-09-01T07:00:00Z","date_published":"2005-09-01T07:00:00Z","updated_at":"2026-07-24T02:53:37Z","subjects":["Physical Therapy","Physiology","Fibromyalgia. Knee; Muscle Strength -- physiology; Female -- physiology."],"languages":["English"],"rights":["This title appears here courtesy of the author, who has granted Loma Linda University a limited, non-exclusive right to make this publication available to the public. The author retains all other copyrights."],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"https://scholarsrepository.llu.edu/etd/989","outbound_label":"Repository record","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["Grenith J. Zimmerman","Keith K. Colburn","Everett B. Lohman III","Bradford D. Martin","James M. Syms"]},{"key":"dc:creator","label":"Author","values":["Shafiee, Flora F."]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"thesis:degree_discipline","label":"Discipline","values":["Physical Therapy Sciences"]},{"key":"thesis:degree_level","label":"Degree Level","values":["Dissertation"]},{"key":"thesis:degree_name","label":"Degree Name","values":["Doctor of Physical Therapy (DPT)"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["Physical Therapy","Physiology","Fibromyalgia. Knee; Muscle Strength -- physiology; Female -- physiology."]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language","label":"Dc Language","values":["English"]},{"key":"dc:rights","label":"Dc Rights","values":["This title appears here courtesy of the author, who has granted Loma Linda University a limited, non-exclusive right to make this publication available to the public. The author retains all other copyrights."]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["https://scholarsrepository.llu.edu/etd/989"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description.abstract","label":"Abstract","values":["Objectives: To compare knee flexors and extensors muscle strength, total work, and power between females with fibromyalgia (FM) and matched healthy controls.
Methods: This is the first study to measure knee muscle power and total work in females with FM. Thirty-one females with FM and thirty-one healthy females completed isokinetic testing of knee flexors and extensors of their dominant leg using a Cybex Norm Isokinetic Dynamometer. Two knee muscle groups (flexors and extensors) at two angular velocities (607sec and 1807sec) were tested for both groups. Both muscle groups were assessed continuously using five reciprocal concentric-concentric cycles, followed by five eccentric-eccentric cycles.
Results:Females with FM exhibited significant decreases in voluntary muscle strength ranging from 18%-24% and average power ranging from 25%-30%, more pronounced for knee flexors than knee extensors. The strength and power deficits were not uniform during all test arrangements: 1) Maximum eccentric muscle strength for knee flexors and extensors at an angular velocity of 60 /sec in females with FM was reduced compared to the control group (p = .005 and .007, respectively), 2) Maximum concentric muscle strength for knee flexors at an angular velocity of 180 /sec in females with FM was reduced compared to the control group (p = .002), and 3) Average power for knee flexors at an angular velocity of 607sec for eccentric muscle action and 1807sec for concentric muscle action in females with FM was reduced compared to the control group (p =.006 and .001, respectively). No differences in total work at the two different velocities for the two muscle actions were found.
Conclusion: We found decreased knee muscle strength and power in females with FM compared to healthy females. This may be due to muscle soreness from unhealed microtraumas, slow deformation of collagen and periarticular connective tissue of the knee joint, hypoxia, or decreased content of high energy metabolites.
"]},{"key":"dc:title","label":"Title","values":["Isokinetic Knee Strength in Females with Fibromyalgia"]}]}],"canonical_facts":{"dc:contributor":["Grenith J. Zimmerman","Keith K. Colburn","Everett B. Lohman III","Bradford D. Martin","James M. Syms"],"dc:creator":["Shafiee, Flora F."],"dc:description.abstract":["Objectives: To compare knee flexors and extensors muscle strength, total work, and power between females with fibromyalgia (FM) and matched healthy controls.
Methods: This is the first study to measure knee muscle power and total work in females with FM. Thirty-one females with FM and thirty-one healthy females completed isokinetic testing of knee flexors and extensors of their dominant leg using a Cybex Norm Isokinetic Dynamometer. Two knee muscle groups (flexors and extensors) at two angular velocities (607sec and 1807sec) were tested for both groups. Both muscle groups were assessed continuously using five reciprocal concentric-concentric cycles, followed by five eccentric-eccentric cycles.
Results:Females with FM exhibited significant decreases in voluntary muscle strength ranging from 18%-24% and average power ranging from 25%-30%, more pronounced for knee flexors than knee extensors. The strength and power deficits were not uniform during all test arrangements: 1) Maximum eccentric muscle strength for knee flexors and extensors at an angular velocity of 60 /sec in females with FM was reduced compared to the control group (p = .005 and .007, respectively), 2) Maximum concentric muscle strength for knee flexors at an angular velocity of 180 /sec in females with FM was reduced compared to the control group (p = .002), and 3) Average power for knee flexors at an angular velocity of 607sec for eccentric muscle action and 1807sec for concentric muscle action in females with FM was reduced compared to the control group (p =.006 and .001, respectively). No differences in total work at the two different velocities for the two muscle actions were found.
Conclusion: We found decreased knee muscle strength and power in females with FM compared to healthy females. This may be due to muscle soreness from unhealed microtraumas, slow deformation of collagen and periarticular connective tissue of the knee joint, hypoxia, or decreased content of high energy metabolites.
"],"dc:identifier":["https://scholarsrepository.llu.edu/etd/989"],"dc:language":["English"],"dc:rights":["This title appears here courtesy of the author, who has granted Loma Linda University a limited, non-exclusive right to make this publication available to the public. The author retains all other copyrights."],"dc:subject":["Physical Therapy","Physiology","Fibromyalgia. Knee; Muscle Strength -- physiology; Female -- physiology."],"dc:title":["Isokinetic Knee Strength in Females with Fibromyalgia"],"thesis:degree_discipline":["Physical Therapy Sciences"],"thesis:degree_level":["Dissertation"],"thesis:degree_name":["Doctor of Physical Therapy (DPT)"]},"updated_at":"2026-07-24T02:53:37Z"}