Motor hand strength is a composite measure of 2 tests: grip and pinch strength.

Grip and pinch strength are measured bilaterally using the Jamar hydraulic hand and pinch dynamometers (Lafayette Instruments, Lafayette, Indiana). Participants are asked to perform each test twice with each hand. The average of these 4 trials for each test represent the performance scores for grip and for pinch strength, in pounds of pressure.

The performance scores are each divided by the sex-specific mean of the parent study at baseline. The values are then averaged to yield a composite measure of hand strength.