Healthy Adults
Conditions
Brief summary
The present study will determine the impact of interrupting prolonged sitting with short, 2-minute walks or body-weight squats on: i) postprandial glycemia and insulinemia, and; ii) postprandial utilization of dietary amino acids. We hypothesize that postprandial glycemia and insulinemia will be similarly improved by interrupting prolonged sitting with short walks or body-weight squats, whereas postprandial utilization of dietary amino acids will only be improved by interrupting prolonged sitting with body-weight squats.
Detailed description
Sedentary behavior is an independent risk factor for chronic disease and premature mortality. Despite a growing awareness of the health risks associated with prolonged sitting, Americans spend upwards of 10 hours per day in a sedentary state. Many leisure-time activities and careers of modern society involve prolonged sitting, necessitating an urgent need to identify strategies that mitigate the health consequences of these behaviors. Recent evidence suggests that interrupting prolonged periods of sitting with short breaks of walking or cycling improve postprandial glucose and lipid handling throughout the day. Thus, relatively small quantities of movement represent an efficacious strategy for improving indices of metabolic health. However, more cost-effective and practical interventions that do not require extra space (i.e. walking) or equipment (i.e. cycling or a treadmill desk) beyond one's immediate sedentary space (e.g. office, desk) would help reduce real and/or perceived barriers of adopting this efficacious disease risk-reduction behavior. A currently understudied consequence of prolonged sitting may also be a desensitization of skeletal muscle's ability to use ingested protein, which overtime can result in detriments to the quantity and quality of this important tissue. Body-weight resistance exercise (RE) can augment the body's ability to use ingested protein to support the maintenance of skeletal muscle mass, and therefore may represent a novel exercise mode to minimize consequences of prolonged sitting. The proposed research will be the first to investigate the influence of interrupting prolonged sitting with short breaks of body-weight resistance exercise (RE) on postprandial glucose and protein metabolism. Importantly, the efficacy of this approach will be directly compared to short breaks of walking, which has previously been reported to improve postprandial glycemia in healthy adults.
Interventions
DIETARY_SUPPLEMENTMixed-macronutrient meal
Participants will be provided a mixed-macronutrient meal (liquid drink) at hours 0 and 3, mimicking the energy and macronutrient composition of breakfast and lunch in Western society (38). 20% of daily energy intake will be provided as breakfast and 30% at lunch. Macronutrient composition will reflect a diet providing 55% energy needs from carbohydrate (CHO) and 1.2g/kg/d protein. The remaining energy requirements, as determined by total energy intake, will be met with dietary fat (estimated to be \ 0.2 and 0.3g/kg fat for breakfast and lunch, respectively), similar to previous liquid mixed-meal approaches.
Sponsors
University of Toronto
Study design
Allocation
RANDOMIZED
Intervention model
CROSSOVER
Primary purpose
TREATMENT
Masking
NONE
Intervention model description
Fourteen men and women will visit the lab on three separate occasions and will remain seated at a desk all-day (Visit 1) or interrupt this sitting every 30-minutes with either 2-minute walking-breaks (Visit 2) or with 15 body-weight squats (repeatedly rising from a chair and onto tip-toes, Visit 3).
Eligibility
Sex/Gender
ALL
Age
18 Years to 35 Years
Healthy volunteers
Yes
Inclusion criteria
* Men and women between 18-35 yr * Recreationally active (≤ 150 minutes of moderate-intensity physical activity per week and no more than 3 days/week of exercise) * VO2peak considered good or below based on ACSM age and sex normative values * Experiencing regular menstrual periods and not taking hormonal oral contraceptives (females only)
Exclusion criteria
* Inability to perform physical activity as determined by the PAR-Q * Inability to adhere to protocol guidelines (e.g. alcohol, standardized diet) * Physical limitations for walking or repeatedly rising from a chair * Regular tobacco use * Illicit drug use (e.g. growth hormone, testosterone) * Hormonal oral contraceptive use (females only) * Diagnosed medical condition under the care of a physician (e.g. type 2 diabetes)
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Postprandial insulin area under the curve (AUC) to breakfast and lunch | 3 hours postprandial | The plasma insulin concentration measured by enzyme-linked immunosorbent assay area under the curve will be measured using the trapezoidal rule. |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Postprandial glucose area under the curve (AUC) to breakfast and lunch | 3 hours postprandial | The plasma glucose concentration measured by hexokinase method area under the curve will be measured using the trapezoidal rule. |
| Skeletal muscle dietary protein incorporation | 7.5 hours postprandial | \[2H5\]Phe and \[13C6\]Phe incorporation into new myofibrillar (contractile) proteins will be determined by LC/MS/MS |
Countries
Canada
Outcome results
None listed