LAUSR

The present study investigated the glycemic response to an acute high‐intensity interval training (HIIT) session (10 one‐minute intervals ≥90% HRmax interspersed with one‐minute of active recovery) versus a moderate‐intensity continuous training (MICT) session (30 min at 64%–76% HRmax) during pregnancy. Twenty‐four normoglycemic females with a singleton pregnancy (27.8 ± 4.7 weeks of gestation, 31.5 ± 4.1 years of age, body mass index: 25.2 ± 11.3) participated in a randomized crossover design study. A flash glucose monitor and accelerometer were worn continuously for 7 days recording glycemic response, physical activity, and sleep. Nutritional intake and enjoyment of the exercise were self‐reported. Average heart rate during exercise was higher for HIIT (82 ± 4% HRmax) compared with MICT (74 ± 4% HRmax; p < 0.001) and participants achieved a peak heart rate of 92 ± 3% during HIIT (range 85%–97% HRmax) compared with 81 ± 4% during MICT (p < 0.001). The change in glucose values from pre‐to‐postexercise were not different between conditions (HIIT: −0.62 ± 1.00 mmol/L; MICT: −0.81 ± 1.05 mmol/L; p = 0.300) with the exception that fewer individuals experienced postexercise hypoglycemia immediately following HIIT compared with MICT (8% versus 33% respectively; p = 0.041). Other glucose variables was not different between exercise protocols. Physical activity (p = 0.07) and caloric intake did not differ (p = 0.10). The majority of participants preferred HIIT (87.5%) and had greater perceived enjoyment compared to MICT (HIIT: 7.8 ± 1.5; MICT: 6.6 ± 2.0; p = 0.015). Sleep duration was 52 ± 73 min longer after participating in HIIT compared with the night prior (main effect for time p = 0.017); no significant changes for MICT. Overall, an acute session of HIIT appears to be well tolerated and demonstrates no adverse effects on maternal glycemic response.