Acute aerobic exercise alters neurotrophic and growth factor concentrations, increases neural activity and improves cognitive and motor function. Additionally, acute exercise increases excitation and reduces inhibition in the motor cortex as assessed via transcranial magnetic stimulation (TMS). The propensity for exercise-induced neuroplasticity may be greater in females, as females show greater neuroplasticity induction following non-invasive brain stimulation (NIBS) compared to males. In females, NIBS yields greater neuroplasticity during ovulation, when estradiol levels are higher, compared to menstruation, suggesting that ovarian hormones may also impact exercise-induced neuroplasticity. To date, it is unknown whether biological sex and ovarian hormones impact neuroplasticity induced by acute aerobic exercise. The present thesis investigated the effects of biological sex and ovarian hormones on the magnitude and direction of neuroplasticity induced by acute aerobic exercise. Fourteen females and fourteen age- and fitness-matched males participated in two sessions in which dependent measures were acquired before and following a single bout of aerobic exercise. Females were tested in the follicular (~day 7) and luteal (~day 21) phases of the menstrual cycle and males were also tested on two occasions separated by ~14 days. The exercise intervention consisted of 5 minutes of warm up, 20 minutes of moderate intensity continuous cycling at 65-70% maximal heart rate, and 5 minutes cool down. TMS was used to obtain motor evoked potential (MEP) recruitment curves and short interval intracortical inhibition (SICI) from the right first dorsal interosseous muscle. Blood measures of estradiol, progesterone, testosterone, and brain-derived neurotrophic factor were assessed before exercise on both testing sessions. Results indicated that only females showed increases in MEP recruitment curve following exercise, and this occurred regardless of menstrual cycle phase. SICI did not change following exercise for males or females on either testing session. The estrogen to progesterone ratio in females was greater in the follicular phase compared to the luteal phase. There was a trend towards greater serum BDNF levels in females in the luteal phase compared to the follicular phase. Sex hormones and BDNF levels did not vary across sessions in males. These findings indicate biological sex, but not ovarian hormones, is an important factor to consider when inducing neuroplasticity using acute exercise. / Thesis / Master of Science (MSc)
| Identifer | oai:union.ndltd.org:mcmaster.ca/oai:macsphere.mcmaster.ca:11375/23744 |
| Date | 11 1900 |
| Creators | El-Sayes, Jenin |
| Contributors | Nelson, Aimee, Kinesiology |
| Source Sets | McMaster University |
| Language | English |
| Detected Language | English |
| Type | Thesis |
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