Background: The thumb plays a critical role for manual tasks during the activities of
daily life and the incidence of neurological or musculoskeletal disorders affecting the voluntary
movements of the thumb is high in the elderly. There is currently no tool to assess repetitive motor
sequencing of the thumb during ageing.
Objectives: To report a novel procedure (the Click Test) assessing the effects of ageing on fast motor
sequencing of the thumb.
Method: Healthy subjects (n = 252; mean age +/- SD: 49.76 +/- 19.97 years; range: 19-89 years;
F/M: 151/101) were asked to perform fast repeated flexion/extension movements of the thumb using
a mechanical counter.
Results: Motor performances (assessed by the number of clicks during 3 time periods: 15, 30 and
45 sec), significantly decreased as a function of age for both the dominant (age effect; p< 0.0001
for 15, 30 and 45 sec) and the non-dominant hand (p<0.0001 for 15, 30 and 45 sec). The number of
clicks was significantly higher in males (gender effect; p<0.001) and was higher on the dominant
side as compared to the non-dominant side (handedness effect: p<0.001). The Click Test is characterized
by high repeatability (coefficients of variation from 3.20 to 4.47%), excellent intra-rater reliability
(intra-class coefficients ICC ranging from 0.89 to 0.98), high inter-rater reproducibility
(Pearson’s product correlation ranging from 0.85 to 0.96), high internal consistency (Cronbach alpha
coefficient=0.95) and is highly correlated in terms of relative performances with the box and
block test and the 9-hole peg test (positive linear correlation with the results of the box and block
test: p<0.001 for 15, 30 and 45 sec for both the dominant and the non-dominant hand; negative linear
correlation with the results of the 9-hole peg test: p<0.001 for 15, 30 and 45 sec for both the
dominant and the non-dominant hand).
Conclusion: The Click Test is an entirely novel and very low cost tool to reliably discriminate the
ageing effects upon the performances during fast repetitive motor sequencing of the thumb. The potential
clinical and research applications for motor functions are multiple, especially in acute and
chronic neurological disorders affecting the thumb as well as in the field of rheumatology and orthopedics.