Date of Award


Document Type


Degree Name

Master of Science (MS)


School of Kinesiology and Recreation

First Advisor

Tyler J Kybartas


Low resting metabolic rate (RMR) and low physical activity (PA) levels are two factors with significant impact on total daily energy expenditure (TDEE) which is one half of the energy balance equation. These two variables can lead to a positive energy balance, which over time can lead to obesity. Assessing the relationships between these variables and respiratory exchange ratio (RER) and substrate utilization is important in understanding how a balanced energy equation can be maintained long-term. PURPOSE: To determine the relationship among RMR, and step counts. METHODS: Volunteer participants ranging from 19-24 years of age (n = 26; 17 men, 9 women; 22.1 ± 1.9y) were recruited for this study. Prior to RMR testing, participants followed a protocol requiring a 6 hour fast, no exercise for 14 hours, and no alcohol or nicotine for 2 hours. Participants reclined, awake, on a padded table in a dimly lit room for 20-25 minutes while respiratory gases were measured using open-circuit spirometry. RMR, RER and substrate utilization were determined during a 5-minute period where variation in VO2 was less than 10%. Following RMR measurement, participants wore an accelerometer on their non-dominant wrist for at least 5 days. Step count data were averaged over days in which the participant had 10 hours of wear time or more. Means and standard deviations were determined for all variables. Spearman correlations were used to determine relationships among the variables. RESULTS: The mean RMR, step count, and RER of participants were 1789.19 ± 385.01 kcal/day, 12872 ± 3773. steps/day, and 0.88 ± 0.08, respectively. Mean substrate utilization was 45.8 ± 25.3% fat and 54.2 ± 25.3% carbohydrates. No significant relationships were found between variables aside from RER and both fat and CHO utilization (r = -0.807, R2 = 0.651, p <0.001). Correlations between other variables were not significant (p>0.05). CONCLUSIONS: Results indicate the only relationship among variables was between RER and substrate utilization. This relationship should always exist due to substrate utilization being calculated using RER values. These results suggest that number of steps taken per day does not have a significant relationship with resting metabolism or RER. Step count may be a better indicator of TDEE than RMR due to PA’s role in calculated TDEE. Further research could explore the potential relationships between RMR and other PA metrics or the relationship between TDEE and RMR.


Imported from Hobson_ilstu_0092N_12141.pdf


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