Deciphering the constrained total energy expenditure model in humans by associating accelerometer-measured physical activity from wrist and hip

The constrained total energy expenditure (TEE) model posits that progressive increases in physical activity (PA) lead to increases in TEE; but after certain PA threshold, TEE plateaus. Then, a compensatory reduction in the expenditure of non-essential activities constrains the TEE. We hypothesized that high PA levels as locomotion associate with a compensatory attenuation in arm movements. We included 209 adults (64% females, mean [SD] age 32.1 [15.0] years) and 105 children (40% females, age 10.0 [1.1] years). Subjects wore, simultaneously, one accelerometer in the non-dominant wrist and another in the hip for >= 4 days. We analyzed the association between wrist-measured (arm movements plus locomotion) and hip-measured PA (locomotion). We also analyzed how the capacity to dissociate arm movements from locomotion influences total PA. In adults, the association between wrist-measured and hip-measured PA was better described by a quadratic than a linear model (Quadratic-R-2=0.54 vs. Linear-R-2=0.52; P=0.003). Above the 80th percentile of hip-measured PA, wrist-measured PA plateaued. In children, there was no evidence that a quadratic model fitted the association between wrist-measured and hip-measured PA better than a linear model (R-2=0.58 in both models, P=0.25). In adults and children, those with the highest capacity to dissociate arm movements from locomotion-i.e. higher arm movements for a given locomotion-reached the highest total PA. We conclude that, in adults, elevated locomotion associates with a compensatory reduction in arm movements (probably non-essential fidgeting) that partially explains the constrained TEE model. Subjects with the lowest arm compensation reach the highest total PA.
Funding Agencies|Fondo Nacional de Desarrollo Cientifico y TecnologicoComision Nacional de Investigacion Cientifica y Tecnologica (CONICYT)CONICYT FONDECYT [11180361]; Spanish Ministry of Education, Culture and Sport [FPU15/04059, FPU15/02645, FPU14/04172]; University of Granada; Spanish Ministry of Economy and Competitiveness; Fondo de Investigacion Sanitaria del Instituto de Salud Carlos IIIInstituto de Salud Carlos III [PI13/01393]; Junta de Andalucia, Consejeria de Conocimiento, Investigacion y UniversidadesJunta de Andalucia; European Regional Development Funds (FEDER)European Commission [SOMM17/6107/UGR]; Redes Tematicas de Investigacion Cooperativa RETIC [Red SAMID RD16/0022]; EXERNET Research Network on Exercise and Health in Special Populations [DEP2005-00046/ACTI]; Fundacion Iberoamericana de Nutricion (ACTIBATE study); AstraZeneca HealthCare Foundation (ACTIBATE study); [PTA 12264-I]