Sex differences in postprandial glucose response to short bouts of exercise: A randomized controlled trial

Exercise Prescription for Postprandial Glycemic Management

The detrimental impacts of postprandial hyperglycemia on health are a critical concern, and exercise is recognized a pivotal tool in enhancing glycemic control after a meal. However, current exercise recommendations for managing postprandial glucose levels remain fairly broad and require deeper clarification. This review examines the existing literature aiming to offer a comprehensive guide for exercise prescription to optimize postprandial glycemic management. Specifically, it considers various exercise parameters (i.e., exercise timing, type, intensity, volume, pattern) for crafting exercise prescriptions. Findings predominantly indicate that moderate-intensity exercise initiated shortly after meals may substantially improve glucose response to a meal in healthy individuals and those with type 2 diabetes. Moreover, incorporating short activity breaks throughout the exercise session may provide additional benefits for reducing glucose response.

Sex differences in the acute effect of stair-climbing on postprandial blood glucose levels: A randomized controlled trial

Single, short stair climbing and descending (SCD) bouts of low to moderate intensity effectively lower postprandial blood glucose but previous reports have found conflicting results on interactions by sex during exercise. We hypothesize that SCD at a self-selected intensity will be equally effective at lowering postprandial blood glucose in males and females. Methods and Results: Thirty subjects (age: 23.8 (3.0) years) performed 0, 1, 3, and 10 min of SCD following consumption of a mixed meal. SCD was performed at a self-selected comfortable pace and all bouts ended at minute 28. Postprandial blood glucose was measured every 15 min for 1 h and analyzed as glucose over time, area under the curve (AUC), and incremental AUC (iAUC) using mixed-design ANOVAs with repeated measures. Although there was no interaction between sex and condition or time (p = .129 to .541) for glucose over time, AUC, or iAUC, there was a main effect for sex for glucose over time (p = .004) and AUC (p = .006), but not iAUC (p = .125). Females had higher blood glucose throughout each trial (22% (13 to 31%), p = .004) but both males' and females’ postprandial blood glucose was lowered following 10 min of SCD relative to the seated control condition. Conclusions: Males and females benefited equally from single, short SCD bouts of low to moderate intensity despite females having higher blood glucose at all time points. Previous findings of sex differences in the attenuating effect of exercise on postprandial blood glucose are likely due to the use of absolute workloads leading to varying relative intensities.

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SCD at a self-selected, comfortable pace for 3 min reduced postmeal blood glucose.

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Men and women benefit equally from SCD postprandial glucose attenuations.

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Previous sex differences were likely due to unequal relative intensity of exercise.

Three minutes of moderate-intensity stair walking improves glucose and insulin but not insulin sensitivity or total antioxidant capacity

BACKGROUND AND AIMS

This study examined the effect of moderate intensity stair stepping exercise on the glycemic response, and antioxidant capacity (TAC) during an oral glucose tolerance test (OGTT).

METHODS AND RESULTS

Thirty participants (women = 12) completed 4 OGTTs during rest or stair walking bouts of 1, 3, and 10 min in a randomized order. Blood was collected at baseline and 30 min during the OGTTs and analyzed for glucose, insulin, TAC, and lactate. Glucose concentrations were decreased following the 10 min (-22.69 (-34.66 to -10.72) mg/dL, p < 0.002) and 3 min (-15.37 (-25.05 to -5.69) mg/dL, p < 0.004) bouts but not the 1 min bout (-6.18 (-19.54 to 7.18) mg/dL, p = 0.352). Insulin concentrations were decreased following the 10 min (-6.11 (-8.86 to -3.36 μIU/dL), p < 0.001) and 3 min (-2.589 (-4.54 to -0.63) μIU/dL, p < 0.012) bouts but not the 1 min bout (-0.37 (-1.87 to 1.13) μIU/dL, p = 0.616). Insulin sensitivity index values showed a significant increase in the 10-min trial (1.81 (0.03-3.58), p < 0.048), but not during the 3 min (0.65 (-0.66 to 1.96) p = 0.317) or 1 min trial (0.13 (-1.58 to 1.84) p = 0.878). There was no omnibus effect for trial in TAC (p = 0.132, η² = 0.07). There was no interaction between trial and time for blood lactate (p = 0.621, η² = 0.02).

CONCLUSION

This study provides evidence bouts as short as 3 min decrease postprandial blood glucose and insulin levels but longer bouts are needed to affect insulin sensitivity.

A single one-minute, comfortable paced, stair-climbing bout reduces postprandial glucose following a mixed meal

BACKGROUND AND AIMS

Postprandial blood glucose (PBG) is an independent predictor of disease and mortality risk. To date, the shortest, single, moderate-intensity exercise intervention to reduce PBG is a 1 min bout of stair stepping during an oral glucose tolerance test. Whether this effect translates to real meal consumption is unknown.

METHODS AND RESULTS

Subjects (N = 30) participated in a randomized controlled crossover trial performing 0 min (seated control), 1 min, 3 min or 10 min of stair climbing and descending bouts (SCD) at a self-selected pace after consumption of a mixed meal on four separate visits. Compared to control, all SCD reduced PBG at least one timepoint: at 30-min the 3 min (-10.8 (-18.7 to -2.8) mg/dL, p = 0.010) and 10 min (-36.3 (-46.4 to -26.3) mg/dL), p < .001), and at 45-min the 1 min (-7.3 (-13.9 to -0.7) mg/dL, p = 0.030, 3 min (-8.7 (-13.9 to -3.6) mg/dL, p = 0.002 and 10 min SCD (-12.2 (-18.2 to -6.1)mg/dL, p < 0.000) reduced PBG. The area under the curve (AUC) for PBG was lower following the 3 min (-4.4% (-7.5 to -1.4%), p = 0.006) and 10 min (-8.9% (-12.4 to -5.3%), p < 0.001), while the incremental AUC (iAUC) was reduced only following the 10 min (-38.0% (-63.7 to -12.3%), p = 0.005) SCD. All SCD were rated by subjects as very light to light intensity.

CONCLUSIONS

Single, subjectively "light" intensity stair climbing and descending bouts as short as 1 min in duration attenuate the postprandial glucose response in normal weight individuals following consumption of a mixed meal. More pronounced effects require longer bouts in a dose-dependent manner.

Reliability of the Polar T31 Uncoded Heart Rate Monitor in Free Motion and Treadmill Activities

The Polar T31 uncoded heart rate monitor (T31) is currently accepted as a precision measurement device that can be used in lieu of electrocardiography. However, minimal literature exists to verify reliability when used for this purpose. The purpose of this study is to evaluate the reliability of heart rate (HR) measurements obtained from the T31. Forty volunteers participated in a three-day test-retest protocol. Participants gave anthropometric data on the first day. On the second day, they performed two 5-minute self-paced free motion walks (FMW) and two 5-minute self-paced free motion jogs (FMJ). Finally, on the third day, they performed two 5-minute treadmill walks (TW) and two 5-minute treadmill jogs (TJ). Treadmill speeds for each TW and TJ were determined by the distances traveled during the FMWs and FMJs on day 2. HR values at rest (HRR) and while in motion (minutes 1-5) were evaluated (HRM). Values calculated used Cronbach's α (≥0.70) for reliability with significance accepted at p<0.05. FMW HRR (all, α=0.96; male, α=0.97; female, α=0.94), FMJ HRR (all, α=0.98; male, α=0.98; female, α=0.99), TW HRR (all, α=0.96; male; α=0.92; female, α=0.98), TJ HRR (all, α=0.97; male, α=0.98; female, α=0.96), FMW HRM (all, α=0.93; male, α=0.93; female, α=0.91), FMJ HRM (all, α=0.93; male, α=0.94; female, α=0.90), TW HRM (all, α=0.95; male, α=0.92; female, α=0.95), TJ HRM (all, α=0.94; male, α=0.95; female, α=0.92). All p-values < 0.001. The T31 provided reliable measures at rest and for walking and jogging in both a free motion and treadmill setting.