Analysis of Pre- and Post- Fatigue Thermal Profiles of the Dominant Hand Using Infrared Imaging

Despite humans' extensive usage of the dominant hand, little has been done to monitor the hand's physical health in terms of development of Upper Extremity Musculoskeletal Disorders. Most of the muscles in the palmar region of the hand are intrinsic, and hence noninvasive EMG measurements give minimal information. In this study, an attempt is made to quantify the variations in thermal profile of the hand pre- and post- fatigue using infrared thermography. Subjects are tested using pinch grip based isometric contraction of the hand until fatigue. Baseline and post-fatigue thermal images are acquired using a Meditherm IRIS infrared camera. The process of image segmentation is carried out to delineate the dominant hand from the background. Features such as average temperature and kurtosis are extracted from the segmented images. Results show that there are wide variations in the intensities depicted by the thermal profile of each subject's hand. A decrease of 1.22% in median hand temperature of the palmar hand is observed. Similarly, a 1.17% reduction in temperature of the dorsal hand is detected post-fatigue. The kurtosis of the thermal profiles increases by 5.39% in the palmar hand and 6.63% in the dorsal hand post-fatigue. The statistical Student T-test performed on these features indicate that the decrease in average temperature is non-statistically significant (P>0.05); however, the increase in kurtosis is statistically significant (P<0.05). Infrared thermography appears to be a promising tool to measure the state of activation of muscle groups using thermal profiles.