Demographics of the sample were: n=812 AA (55% women, average age 19.5±17.3 yrs) and n=4055 White (54% women, 22.1± 21.4yrs). There was a difference in 4-meter walk (p=0.001) and 4-meter walk fast (p=0.03), with AA faster than White individuals. Grip strength was also dissimilar in the dominant hand (p<.001) and nondominant hand (p=<0.001), with AA stronger than Whites. Balance was better in AA (p=0.001). There was no difference in 2-meter walk (p=0.07), 9-hole pegboard (p=0.7), knee strength (p=0.64) and balance sway (p=0.82). When the data was restricted to individuals over 40 (n=812 AA, 66% women, 56.3±11.6 yrs) and n=4055 White (56% women, 61.4±13.1yrs), knee extension strength was weaker in the AA compared to White individuals in the dominant (42.2 vs. 66.4, p=0.03) and non-dominant leg (42.2 vs. 55.4, p=0.02). Balance and balance sway were better in the AA compared to Whites (0.7 vs. 0.4, p<0.001) and (0.37 vs. 0.35, p=0.03).

Researchers using the NIH toolbox motor measures in various racial groups should be cautious to adjust for baseline differences in the data. Without adjustment, differences seen in disease populations may be due to normative data differences rather than attributable to the disease under study.