Table 3.
Mean Functional Mobility, Fitness, and Fatigue Parameter Values* by FT4 and TSH Category† Overall and Within Sex-Strata
| Measures | FT4 Level† | ||
|---|---|---|---|
| Low (Q1) | Medium (Q2–Q3) | High (Q4) | |
| Overall | |||
| N = 602, No. | 141 | 295 | 166 |
| Walking ability index score‡, points | 8.06§,‖ | 7.51 | 7.17 |
| Usual gait speed‡, m/s | 1.12§,¶ | 1.08 | 1.03‖ |
| Rapid gait speed‡, m/s | 1.70§,** | 1.60 | 1.52‖ |
| 400-m time††,‡‡, s | 290¶,§§ | 304 | 309 |
| Fatigability rating‡‡,‖‖, points | 8.90¶¶ | 9.12 | 9.50 |
| Energy level past month‡‡, points | 7.70§§ | 7.43 | 7.21 |
| Frequency a lot of energy past 4 weeks*** | 2.39§,¶ | 2.61 | 2.78 |
| Men | |||
| N = 335, No. | 76 | 165 | 94 |
| Walking ability index score, points | 8.12¶,¶¶ | 7.56 | 7.47 |
| Usual gait speed***, m/s | 1.14§ | 1.09 | 1.03¶ |
| Rapid gait speed***, m/s | 1.75§,¶ | 1.66 | 1.58 |
| 400-m time††,s | 283 | 295 | 300 |
| Fatigability rating‖‖, points | 9.00 | 9.06 | 9.46 |
| Energy level past month***, points | 7.93‖,§§ | 7.31 | 7.28 |
| Frequency a lot of energy past 4 weeks*** | 2.27§,‖ | 2.64 | 2.79 |
| Women | |||
| N = 267, No. | 65 | 130 | 72 |
| Walking ability index score***, points | 7.98§§ | 7.46 | 6.79¶ |
| Usual gait speed‡‡, m/s | 1.11§§ | 1.07 | 1.02 |
| Rapid gait speed‡, m/s | 1.63§,‖ | 1.52 | 1.45 |
| 400-m time††,***, s | 297¶,§§ | 314 | 327 |
| Fatigability rating‖‖, points | 8.79¶¶ | 9.20 | 9.56 |
| Energy level past month, points | 7.47 | 7.58 | 7.10¶ |
| Frequency a lot of energy past 4 weeks | 2.52 | 2.57 | 2.77 |
| Measures | TSH Level† | ||
| Low Normal | High Normal | Subclinical Hypothyroid | |
| Overall | |||
| N = 602, No. | 320 | 217 | |
| Walking ability index score, points | 7.45 | 7.67 | 7.57 |
| Usual gait speed, m/s | 1.08 | 1.07 | 1.07 |
| Rapid gait speed, m/s | 1.59 | 1.62 | 1.59 |
| 400-m time††, s | 302 | 299 | 309 |
| Fatigability rating‖‖, points | 9.21 | 9.04 | 9.27 |
| Energy level past month, points | 7.31¶ | 7.63 | 7.40 |
| Frequency a lot of energy past 4 weeks | 2.64 | 2.58 | 2.53 |
| Men | |||
| N = 335, No. | 171 | 126 | 38 |
| Walking ability index score, points | 7.61 | 7.81 | 7.39 |
| Usual gait speed, m/s | 1.10 | 1.09 | 1.06 |
| Rapid gait speed, m/s | 1.65 | 1.69 | 1.60 |
| 400-m time††,s | 291 | 292 | 308 |
| Fatigability rating‖‖, points | 9.32 | 8.84 | 9.32 |
| Energy level past month‡, points | 7.19** | 7.86 | 7.21¶ |
| Frequency a lot of energy past 4 weeks | 2.70¶ | 2.46 | 2.61 |
| Women | |||
| N = 267, No. | 149 | 91 | 27 |
| Walking ability index score, points | 7.24 | 7.49 | 7.99 |
| Usual gait speed, m/s | 1.06 | 1.05 | 1.08 |
| Rapid gait speed, m/s | 1.52 | 1.52 | 1.58 |
| Measures | TSH Level† | ||
| Low Normal | High Normal | Subclinical Hypothyroid | |
| 400-m time††, s | 317 | 308 | 303 |
| Fatigability rating‖‖, points | 9.12 | 9.30 | 9.05 |
| Energy level past month, points | 7.44 | 7.32 | 7.71 |
| Frequency a lot of energy past 4 weeks | 2.56 | 2.74 | 2.43 |
Notes: *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.
†FT4 categories defined by sex-specific quartiles, with low comprising the lowest quartile, medium the two middle quartiles, and high the highest quartile. Cutpoints are (0.76–0.89, 0.90–1.09, 1.10–1.50) for men and (0.76–0.90, 0.91–1.07, 1.08–1.50) for women. TSH categories for low normal, high normal, and subclinical hypothyroid are defined respectively as 0.40–2.49, 2.50–4.49, and 4.50–9.99.
‡ p < .001 for trend.
§ p < .001 from high group.
‖ p < .01 from medium group.
¶ p < .05 from medium group.
** p < .001 from medium group.
††Persons able to complete the full 400-m walk only (281 men and 215 women).
‡‡ p < .05 for trend.
§§ p < .01 from high group.
‖‖Subsample administered the fatigability test which was implemented later in the study (290 men and 224 women).
¶¶ p < .05 from high group.
*** p < .01 for trend.