Table 2.

Cross-sectional Associations* Between FT4 and TSH and Functional Mobility, Fitness, and Fatigue

Measures	Overall		Men		Women
No.	602		335		267
	β (SE) p-Value		β (SE) p-Value		β (SE) p-Value
	FT4 (units = 0.1ng/dL)
Walking ability index score	−.214 (.066)	.001	−.141 (.082)	.087	−.331 (.110)	.003
Usual gait speed	−.025 (.006)	<.001	−.029 (.008)	<.001	−.022 (.009)	.019
Rapid gait speed	−.040 (.010)	<.001	−.033 (.013)	.015	−.046 (.014)	.001
400-m time†	4.93 (1.97)	.013	5.89 (2.53)	.021	5.66 (3.05)	.061
Fatigability rating‡	.243 (.073)	<.001	.226 (.098)	.022	.278 (.111)	.013
Energy level past month	−.147 (.051)	.004	−.160 (.066)	.016	−.134 (.081)	.099
Frequency a lot of energy past 4 weeks	.100 (.033)	.002	.134 (.042)	.002	.047 (.053)	.375
	TSH (units = 1.0 mU/L)
Walking ability index score	.044 (.057)	.441	−.001 (.071)	.999	.143 (.010)	.135
Usual gait speed	−.002 (.005)	.752	−.007 (.007)	.315	.007 (.008)	.372
Rapid gait speed	.004 (.008)	.636	−.006 (.012)	.616	.017 (.012)	.171
400-m time†	0.67 (1.67)	.689	2.25 (2.27)	.154	−4.17 (2.38)	.082
Fatigability rating‡	−.009 (.061)	.884	−.044 (.085)	.609	.007 (.090)	.937
Energy level past month	.078 (.044)	.077	.088 (.058)	.128	.080 (.070)	.254
Frequency a lot of energy past 4 weeks	−.035 (.029)	.228	−.044 (.037)	.244	−.021 (.045)	.649

Notes: FT4 = free thyroxine; TSH = thyroid stimulating hormone.

*Adjusted for age, race, exercise level, smoking status, weight in kilograms, and height in centimeters for all and walking aid use for usual and rapid gait speed, 400-m time and fatigability only.

^†Persons able to complete the full 400-m walk only (281 men and 215 women).

^‡Subsample administered the fatigability test which was implemented later in the study (290 men and 224 women).