Issues in accelerometer methodology: the role of epoch length on estimates of physical activity and relationships with health outcomes in overweight, post-menopausal women

Table 4 Relationship between inactivity [adjusted for wear time (min/day)] accumulated in 60 and 10 second epochs and health outcome measures (n = 102).

	60s epoch	10s epoch	Test for Difference Between Correlations p value	60s epoch β	10s epoch β	Test for Equality of Slope p value
	ρ	ρ
Anthropometric Measures
Body weight, lbs	-0.077	-0.077	0.98	-0.0003	-0.0002	0.56
Body Mass Index, kg/m²	-0.073	-0.055	0.40	-0.0015	-0.0009	0.30
Waist Circumference, cm	0.053	0.042	0.61	0.0004	0.0003	0.49
Whole body fat mass, kg	-0.011	0.014	0.24	-0.0001	0.0001	0.44
Trunk fat mass, kg	0.030	0.056	0.24	0.0000	0.0000	---
Whole body lean mass, kg	-0.037	-0.038	0.97	-0.0000	-0.0000	---
Trunk lean mass, kg	-0.008	-0.006	0.93	-0.0000	-0.0000	---
Bone Parameters
Spine, g/cm²	-0.006	0.009	0.48	-0.0036	0.0041	0.64
Trochanter, g/cm²	-0.033	-0.047	0.51	-0.0244	-0.0277	0.88
Intertrochanter, g/cm²	0.003	0.009	0.77	0.0019	0.0044	0.88
Femoral Neck, g/cm²	-0.100	-0.092	0.70	-0.0781	-0.0568	0.33
Hip, g/cm²	-0.015	-0.013	0.92	-0.0108	-0.0074	0.86
Physical Activity
Leisure Physical Activity, MET∙hr∙wk^{-1 b}	-0.255*	-0.302**	0.03	-0.0014**	-0.0013***	0.51
400 m walk, s ^d	0.031	0.048	0.43	0.0001	0.0001	0.80
Cardiovascular Disease Risk Factors
Systolic Blood Pressure, mmHg	0.028	0.039	0.60	0.0002	0.0002	0.92
Diastolic Blood Pressure, mmHg	-0.016	-0.008	0.70	-0.0002	-0.0001	0.72
Total Cholesterol, mg/dL ^a	-0.179^†	-0.161	0.39	-0.0004^†	-0.0003	0.07
LDL-c, mg/dL ^a	-0.123	-0.099	0.26	-0.0003	-0.0002	0.12
HDL-c, mg/dL ^a	-0.154	-0.148	0.76	-0.0008	-0.0006	0.18
Triglycerides, mg/dL ^a	0.036	0.014	0.30	0.0001	0.0000	0.38
Insulin, mg/dL ^c	0.212*	0.224*	0.57	0.0036*	0.0030*	0.23
Glucose, mg/dL ^a	0.182^†	0.166^†	0.45	0.0014^†	0.0010^†	0.07

^†P < 0.10; *P < 0.05; **P < 0.01; ***P < 0.001; ^a n = 101; ^b n = 100; ^c n = 99; ^d n = 90

ISSN: 1479-5868