Table 2 Accuracy of V̇O2peak estimations compared to directly measured V̇O2peak in people with overweight and obesity at baseline.

From: V̇O2peak estimation in people with overweight and obesity before and after a 14-week lifestyle intervention

Algorithm

VO2peak estimation equation

Bias ± 95% CI

R2

SEE

MAPE

SCG 4.6

65.811 + (14.772·Sex [men = 1 & women = 0]) + (–0.229·Age) + (-0.300·Weight [kg]) + (0.092·Height [cm]) + (0.002·RR) + (4.671·Log_amp_AC_PeaktoPeak) + (-0.073·S2Morphology) + (0.197·S1FrequencySpec) + (-0.202·S2FrequencySpec) + (–70.894·amp_Ds) + (7.356·amp_range_s2_log_100) + (228.86·ampEs_40) + (–600.74·amp_s1_std_150)

0.3 ± 1.0

0.61

5.0

14.9

Myers et al. [22]

79.9–(0.39·age)–(13.7·sex [men=0 & women = 1])–(0.127·weight [lbs])

−0.4 ± 1.1

0.50

5.8

17.1

Schembre and Riebe

2011 [21]

47.749 – (6.493·sex [men = 1 & women = 2]) + (0.140·√vigorous activity [MET min·week-1])

13.3 ± 1.3***

0.13

15.0

57.9

No SCG

36.956 + (–0.302·Age) + (13.045·Sex [men = 1 & women = 0]) + (–0.458·Weight [kg]) + (0.257·Height [cm])

−0.3 ± 1.3

0.61

5.4

17.7

  1. V̇O2peak is in ml·min–1·kg–1. 1 kg = 2.205 lbs. Vigorous activity is based on self-reported VPA with the International Physical Activity Questionnaire short form (IPAQ-S) and calculated into MET min·week–1 using the formula: VPA MET min·week–1 = 8.0 · VPA min · VPA days. SCG equation feature description: RR, the average duration of a heartbeat at rest; Log_amp_AC peak to peak, log-transformed peak to peak amplitude in SCG diastolic complex; S2Morphology, morphology of the average SCG diastolic complex quantified using PCA; S1FrequencySpec, frequency of the average SCG systolic complex quantified using PCA; S2FrequencySpec, frequency of the average SCG diastolic complex quantified using PCA; amp_Ds, the amplitude of Ds point in the SCG signal; amp_range_s2_log_100, the amplitude of the diastolic complex after high pass filtering (100 Hz); ampEs_40, amplitude of Es point in SCG signal after high pass filtering (40 Hz), amp_s1_std_150, range of the amplitude of the systolic complex after high pass filtering (150 Hz). The No SCG equation is developed using 372 recordings from 221 subjects and validated in 138 recordings from 74 subjects from the 4.6 database, from which the SCG 4.6 is also developed. A significance level of α = 0.05 was applied. *** p < 0.001. n = 67 for the SCG equation (Schmidt et al. 2024, version 4.6), No SCG equation and Myers et al. [22], n = 64 for Schembre and Riebe 2011 [21].
  2. SCG seismocardiography; eV̇O2peak estimated peak oxygen consumption; SEE standard error of estimation; MAPE mean absolute percentage error; MET metabolic equivalent of task; PCA principal component analysis; VPA vigorous physical activity.
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