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-R2 = 0.54 vs. Linear-R2 = 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 (R2 = 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.

Fondo Nacional de Desarrollo Científico y Tecnológico (11180361 to R.F.-V.); Spanish Ministry of Education, Culture and Sport (FPU15/04059 to J.M.A.A.; FPU15/02645 to J.H.M.; FPU14/04172 to F.J.A.-G.); University of Granada (Plan Propio de Investigación 2019 [Programa Contratos-Puente] to F.J.A.-G.; Plan Propio de Investigación 2016 [Excellence actions: Unit of Excellence on Exercise and Health UCEES]); Spanish Ministry of Economy and Competitiveness (ACTIBATE study; ACTIVEBRAINS study); Fondo de Investigación Sanitaria del Instituto de Salud Carlos III (PI13/01393 to ACTIBATE study); Junta de Andalucía, Consejería de Conocimiento, Investigación y Universidades and European Regional Development Funds (FEDER: ref. SOMM17/6107/UGR to ACTIBATE study); Redes Temáticas de Investigación Cooperativa RETIC (Red SAMID RD16/0022 to ACTIBATE study); EXERNET Research Network on Exercise and Health in Special Populations (DEP2005-00046/ACTI); Fundación Iberoamericana de Nutrición (ACTIBATE study); AstraZeneca HealthCare Foundation (ACTIBATE study); PTA 12264-I to FIT-AGEING study.