<p> During exercise in a hot climate, it has been reported that children respond with a greater shift in blood volume from the central to the peripheral circulation, compared with adults. This can lead to inadequate central circulation, and early cessation of activity in children. No studies have considered if a transition in this hemodynamic response occurs during puberty in females. This study measured hemodynamic responses in pre/early (PEP), mid- (MP), and late- (LP) pubertal girls. Twenty-seven 9- to 16- year-old healthy girls (n=9, each group) cycled in a climatic chamber set at 35 ± 1°C and 50 ± 5% relative humidity for two 20-min bouts (10-min rest in between and a 10-min rest at the end). Cardiac output was
measured upon chamber entry, in the middle and at the end of each exercise bout. Forearm blood flow (FBF) was measured upon chamber entry, 3 minutes after exercise bout 1 (E1) and bout 2 (E2) and at the end of rest 1 (R1) and rest 2 (R2). Overall, there was no significant group difference in the central hemodynamic (e.g. cardiac index, stroke volume index) responses to exercise in the heat. However, FBF among the three groups at R1 was almost significantly different (p=0.06), such that it was lower in LP than in PEP and MP. FBF in LP
also tended to decrease from E1 to R1 (7.91±1.06 to 6.1±0.83 ml•100ml-1•min-1) and from E2 to R2 (9.47±1.47 to 8.26±1.20 ml•100ml-1•min-1). In contrast, PEP and MP showed little change in FBF at all time points. These findings strengthen the notion that there is a maturity-related decrease in forearm blood flow from pre- to late-puberty. In conclusion, under the conditions of the present study, there were very few differences in the hemodynamic responses of pre-, mid- and late- pubertal girls. It is possible that the transition to an adult-like hemodynamic response does not occur until later in a girl's physical development.</p> / Thesis / Master of Science (MSc)
| Identifer | oai:union.ndltd.org:mcmaster.ca/oai:macsphere.mcmaster.ca:11375/22494 |
| Date | 12 1900 |
| Creators | Brien, Erin |
| Contributors | Bar-Or, Oded, Human Biodynamics |
| Source Sets | McMaster University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis |
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