Creative Commons License

Creative Commons License
This work is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 4.0 License.

Date of Award

Spring 2015

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Department of Kinesiology

Advisor(s)

Elizabeth Skidmore Edwards

Jeremy Akers

Abstract

Abstract

Purpose: The primary purpose of this study was to compare the effects of an 8-week run-sprint interval training (R-SIT) and continuous moderate-intensity training (MIT) on fasting blood glucose, HbA1c, insulin sensitivity, and β-cell function in sedentary, prediabetic adults. Secondary outcomes of the study included anthropometric, body composition variables, and aerobic capacity.

Methods: Sedentary, physician diagnosed prediabetic individuals were randomized into R-SIT (n=7, BMI 36.76 ± 9.79) or MIT (n=8, BMI 40.59 ± 12.49) interventions. Subjects participated in supervised exercise three times a week and attended a Diabetes Prevention Program course, once weekly. R-SIT participants performed 4-6 x 30-second “all-out” treadmill sprints, interspersed with a 4-minute active recovery at 2-2.5 mph. MIT participants performed 30-40 minutes of continuous moderate-intensity exercise at 45-55% HRR. Analysis of fasting blood glucose, HbA1c, and fasting insulin were obtained at baseline and 8-weeks. Insulin sensitivity (%) and β-cell function (%) were assessed via HOMA2-IR. Body composition, assessed via dual x-ray absorptiometry, and aerobic capacity assessed during a treadmill ramp protocol, were also obtained before and after 8-weeks of training.

Results: Across groups, HbA1c improved across time (p = 0. 042). There were no significant changes in fasting blood glucose, insulin sensitivity, or β-cell function in either group. Relative VO2max significantly improved in the R-SIT participants (+1.63 ± 1.75mL*kg-1*min-1), whereas no change in relative VO2max occurred in the MIT participants. Significant differences in body composition following 8-weeks of exercise occurred only in the MIT group, as measured by body weight (-9.35 ± 6.21 lb.), BMI (-1.21 ± 1.07 kg/m2), BF% (-2.02 ± 1.88%), and LM% (+2.05 ± 1.84%).

Conclusion: Eight weeks of exercise improved HbA1c in prediabetic participants. Although no other improvements in glycemic control were demonstrated in either group, R-SIT participants demonstrated improvements in aerobic capacity, despite exercising at maximal intensities for only two to three minutes per session. In contrast, body composition significantly improved in the MIT group only. These findings suggest that 8-weeks of R-SIT training may be an effective strategy for improving cardiorespiratory fitness levels in overweight and obese prediabetic individuals, but is not effective in improving body composition.

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