Glycemic Response to Acute High-Intensity Interval Training versus Moderate-Intensity Continuous Training during Pregnancy
Creators: Wowdzia, Jenna B
Publisher: name: University of Alberta Library
Year: 2022

<p>Moderate-intensity continuous training (MICT) continues to be the staple of prenatal physical activity research. The glucose lowering effects of MICT are well established with low risk of post-exercise hypoglycemia, however there is a large research gap concerning maternal response to short bursts of vigorous-intensities. Despite the growing number of individuals continue to participate in high-intensity interval training (HIIT) following conception, pregnant individuals glycemic response to HIIT has only been reported once with pre to post exercise capillary glucose samples. Since glucose is essential to supporting the maternal physiological adaptations to prepare the body for the demands of pregnancy and assist in fetal-placental growth, it is imperative to further investigate the glucose lowering effects of HIIT. Furthermore, the vast majority of vigorous-intensity research with pregnant populations has not exceeded 90% maternal HRmax and the effects on maternal glucose are essentially unknown. Therefore we sought to investigate maternal glycemic response during and following an acute bout of HIIT and MICT in pregnant individuals over a 48 hour period.<br>
We recruited 24 pregnant females (27.8 ± 4.7 weeks of gestation, 31.5 ± 4.1 years of age) with a singleton pregnancy to participate in this randomized cross over design study. Each participant wore a flash glucose monitor and accelerometer, as well as kept a written food log, for seven days to collect 24 and 48 hour glucose values, physical activity patterns, and caloric intake. The participants engaged in two acute bouts of exercise (i.e., one HIIT and MICT session) in random order separated by 48 hours. The HIIT protocol consisted of 10 one minute intervals of high-intensity work (i.e., &gt; 90% HRmax) interspersed with nine one minute intervals of active recovery (19 minutes total). The MICT protocol consisted of 30 minutes of moderate- intensity cycling (i.e., 64 – 76% HRmax). Post-exercise participants were asked to report their<br>
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perceived enjoyment and overall preference for HIIT or MICT. During the HIIT protocol, participants achieved peak heart rates of 159 - 185 bpm (85 - 97% of HRmax) with an average heart rate throughout the HIIT session (155 ± 8 bpm; 82 ± 4% HRmax) being significantly higher than during MICT (140 ± 8 bpm; 74 ± 4% HRmax; P &lt; 0.0001). The change in glucose from pre to post exercise were not significantly different between conditions (HIIT: 0.62 ± 1.00 mmol/L; MICT: 0.81± 1.05 mmol/L; P = 0.30) with the exception that fewer individuals experienced post- exercise hypoglycemia after HIIT compared to MICT (8% versus 33% respectively; P = 0.04). All other glucose variables were not different between exercise protocols including mean 24 and 48 hour glucose, or time spent &lt; 3.3 mmol/L or &gt; 7.8 mmol/L. Physical activity patterns (sedentary time, light, and moderate to vigorous intensity physical activity) and caloric intake (macronutrients and total calories) were not different between conditions or days. In comparison to MICT, HIIT was preferred by the majority of participants (87.5%). Sleep time following HIIT was 52 ± 73 minutes longer than the night before the HIIT session, while sleep after engaging in MICT was not changed. To our knowledge, this study is the first to report on the 48 hour glycemic response to aerobic HIIT with pregnant populations. Overall, an acute session of HIIT had no adverse effects on maternal glycemic response and elicited higher levels of perceived enjoyment in comparison to MICT. Results from this study improve healthcare provider and participant understand of the effects of HIIT. Future research is necessary to determine the effect of HIIT on fetal response as well as in individuals diagnosed with metabolic disorders such as gestational diabetes mellitus.</p>