Show simple item record

dc.contributor.authorInglis, J Greig
dc.date.accessioned2019-02-22T19:02:32Z
dc.date.available2019-02-22T19:02:32Z
dc.identifier.urihttp://hdl.handle.net/10464/13966
dc.description.abstractSex-differences in muscle strength have been linked to differences in muscle size, involved limb, and daily activities. Early work has shown that sex-differences are greater in the upper compared to lower limb, making the upper limb an ideal model to investigate the best statistical approaches for sex comparison. Large differences in the upper limb reveals how biomechanical factors may impact neural control. Since males and females are more comparable with respect to strength in the lower limb, it allows for a determination of whether potential sex-differences in neural control exist without large differences in biomechanics. Understanding sex-differences allows for prescription of rehabilitation and training modalities, taking into account potential specificities in sex-related neuromuscular and musculoskeletal factors. The overall purpose was to examine neural and biomechanical differences that would account for sex-differences in neural control of muscle. Manuscript 1 examined normalization versus an ANCOVA to assess sex-differences. Sex-differences were seen in elbow flexor strength and rate of force development (RFD). Normalization by either maximum strength or neural factors couldn’t account for all sex-differences in RFD, resulting in an ambiguous interpretation. In contrast, both variables were able to be incorporated in an ANCOVA to determine their relative contribution. Manuscript 2 examined the effect of task familiarization and the contribution of maximum strength, twitch contraction time, muscle fiber condition velocity, and rate of muscle activation to sex-differences in the RFD during dorsiflexion. There were no significant differences between the sexes in muscle properties, but there were differences in neural control. Additionally, across days females exhibited a neural adaptation leading to an improvement in the RFD. Manuscript 3 directly assessed potential sex-differences in neural control during force gradation by recording motor unit activity during maximal and submaximal contractions. Females had less force steadiness (FS), which may have resulted from neural compensation for a less optimal pennation angle or a tendency towards greater joint laxity. Higher motor unit discharge rates and incidence of doublets may increase twitch force summation leading to a reduction in FS. Thus, biomechanical, not inherent sex-differences in neural drive led to neural compensation strategies manifesting as a difference in FS.en_US
dc.language.isoengen_US
dc.publisherBrock Universityen_US
dc.subjectmotor unit discharge rate, sex differences, force steadiness, rate of force development, neuromechanicsen_US
dc.titleSex differences in the neural control of muscleen_US
dc.typeElectronic Thesis or Dissertationen_US
dc.degree.namePh.D. Applied Health Sciencesen_US
dc.degree.levelDoctoralen_US
dc.contributor.departmentApplied Health Sciences Programen_US
dc.degree.disciplineFaculty of Applied Health Sciencesen_US
refterms.dateFOA2020-01-10T00:00:00Z


Files in this item

Thumbnail
Name:
Brock Inglis, J Greig 2018.pdf
Size:
6.287Mb
Format:
PDF

This item appears in the following Collection(s)

Show simple item record