Validation of a Combined Heart Rate and Accelerometry Method for Measuring Total Energy Expenditure in Soccer Players During Precompetition Training

ABSTRACT: Kim, N, Lee, S, Taguchi, M, Oh, T, Han, S, Ishikawa-Takata, K, and Park, J. Validation of a combined heart rate and accelerometry method for measuring total energy expenditure in soccer players during precompetition training. J Strength Cond Res XX(X): 000-000, 2026-Understanding energy expenditure in athletes during intensive training periods is essential for optimizing performance and recovery. Accurate assessment of total energy expenditure (TEE) and activity energy expenditure (AEE) during precompetition training is important. Accordingly, TEE and AEE were assessed using the doubly labeled water (DLW) method. We also validated a combined method using exercise energy expenditure (EEE) through heart rate (HR) and nonexercise activity thermogenesis (NEAT) through accelerometry (ACC) in collegiate soccer players, examining EEE and NEAT variability in relation to TEE. Korean male collegiate soccer players participated in the study. TEEDLW and AEEDLW were measured over 8 days using DLW (n = 14). Resting metabolic rate (RMR) was assessed with the Douglas bag method. TEECOM was calculated as the sum of RMR, HR-derived EEE, and ACC-derived NEAT (n = 10). TEEDLW and AEEDLW were 4,119 and 2,066 kcal·d-1, respectively. TEECOM and AEECOM (4,090 and 2,028 kcal·d-1, respectively) closely matched TEEDLW and AEEDLW (4,062 and 2,002 kcal·d-1, respectively), showing high validity (r2 = 0.81 and 0.73, respectively). Bland-Altman analysis revealed small mean differences: 21.17 kcal·d-1 for TEE and 25.75 kcal·d-1 for AEE. Heart rate-derived EEE correlated strongly with AEEDLW (r = 0.77, p = 0.009), while ACC-derived NEAT and HR-derived EEE were negatively correlated (r = -0.74, p = 0.014). Higher TEE and AEE values corresponded with increased training volume. The combined HR and ACC method proved highly valid for group-level TEE assessment. Owing to individual variability in EEE and NEAT, precise measurement of these components remains crucial for accurate TEE predictions in athletes.