Abstract
This study aimed to compare the target heart rate (THR) for aerobic exercise based on standardized physiological maximum value percentages with the first-ventilatory-threshold heart rate (HR(VT1)) in individuals with metabolic syndrome. Three HR(max) prediction equations were used to calculate the THR as 35%, 40% and 45% of the heart rate reserve (HRR) and 55%, 60% and 65% of the HR(max), and the results were compared with the HR(VT1). The HR(VT1) was measured through a CPET that complied with current guidelines and laboratory standards. In addition, the THRs calculated by combining the HR(max)-measured values with standardized methods were compared with those of HR(VT1) as a supplement for situations where HR(max)-measured values can be evaluated but gas exchange analysis cannot be performed. According to the Fox equation, the difference between the HR(VT1) and 35% HRR was not statistically significant (t = - 0.528, P = 0.600). Bland‒Altman analysis indicated that the mean difference between the two values was - 0.350, which was close to the 0th line (SD: ± 4.595; 95% CI - 1.684-0.984), with 95% limits of agreement ranging from - 9.356 to 8.656; the interclass correlation coefficient (ICC) was 0.862 (P < 0.001, 95% CI 0.766-0.920), indicating high reliability. Regarding the results, the measured values indicate that 40% HRR and 70% HR(Peak) showed good reliability with HR(VT1) (ICC: 0.850, 95% CI 0.747-0.913; and ICC: 0.719, 95% CI 0.551-0.832, respectively). Among Chinese patients with MetS, the THR calculated by combining the standardized 35% HRR method with the Fox equation shows excellent agreement with the HR(VT1) obtained from the CPET. When the HR(Peak) can be obtained, the THR calculated from the 40% HRR and 70% HR(Peak) can better estimate the HR(VT1). The above results can be used to guide patients to gradually start exercise training near the VT1 in cases where CPET data cannot be obtained.