Blood Lactate Predicts Resting Energy Expenditure in Non-Obese Caucasian Females

ECU Author/Contributor (non-ECU co-authors, if there are any, appear on document)

Zhen Wei Yang (Creator)

Institution

East Carolina University (ECU )

Web Site: http://www.ecu.edu/lib/

Abstract: Background: Obesity and Type 2 Diabetes are both global epidemics that continue to skyrocket. High basal plasma lactate levels , reduced oxidative capacity , and insulin resistance are co-morbidities with these metabolic disorders. However , it is unknown if those co-morbid traits are also displayed in the non-obese who may be predisposed to obesity. A higher plasma lactate concentration is the product of the shift to anaerobic glycolysis due to the reduction of oxidative capacity. With aerobic respiration being limited , we believed it would reduce the resting energy expenditure (REE) , and potentially propel an individual toward obesity and related metabolic disease(s). Purpose: The purpose of the study was to investigate if plasma lactate can be used to predict resting energy expenditure in non-obese humans. Methods: Non-obese subjects (n=40) with body mass index (BMI) between 18.5-26.0 kg/m2 were screened for plasma lactate concentration. Subjects with the highest (n=10) and lowest (n=11) plasma lactate were selected and grouped into a High Lactate (High) and a Low Lactate (Low) Group. Both groups had their body composition , REE , resting respiratory exchange ratio (RER) , and aerobic capacity (VO2 peak) assessed on the first testing day. Blood measurements , and oxidative capacity were assessed using near infrared spectroscopy (NIRS) , and submaximal exercise RER (low intensity at 50% VO2 peak) were assessed on the second testing day. Results: Lactate and REE were negatively correlated (R=-0.6093) in the High Lactate Group. This correlation was stronger when REE was adjusted for fat free mass (FFM) (R=-0.6823 , P<0.05). Aerobic capacity adjusted for FFM was significantly lower in the High Lactate Group (P<0.05). Lactate and aerobic capacity adjusted for FFM also revealed a strong relationship (R=-0.7232 , P<0.001). Lactate and oxidative capacity demonstrated a negative relationship (R=-0.364) in the High Lactate Group. Lactate and substrate change ([delta]RER) from resting to submaximal exercise were strongly correlated (R=0.6393 , P<0.05). Laboratory blood analysis showed no difference in plasma lactate , insulin or glucose. Conclusion: Lactate is associated with resting energy expenditure in non-obese Caucasian females. The inability for higher lactate individuals to match more fat substrates utilized as the lower lactate subjects may be an indication of a lesser mitochondrial and capillary density. The implication of early signs of elevated lactate concentrations may be an indicator of a compromised energy transduction capacity , which may be a contributor to obesity. Further research is needed to look at the plasma lactate concentration , and oxidative capacity affecting energy expenditure.

Additional Information

Publication

Thesis

Language: English

Date: 2019

Keywords

Caucasian, Females, Resting Energy Expenditure, REE, Respiratory exchange ratio, RER, metabolic inflexibility, non-obese, metabolic syndrome

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