Fig. 2

Biplot of Principal Component Analysis (PCA) of the actigraphy variables. The x-axis represents the first principal component (PC1), which explains 54.6% of the total variance and is strongly associated with vector magnitude average counts (VMA) across all axes (both affected and less-affected side), percentage in moderate-to-vigorous physical activity (MVPA; affected side), and average MVPA per hour (affected side). These associations suggest that PC1 primarily represents the activity time and distance measures in actigraphy. The y-axis represents the second principal component (PC2), accounting for 21.9% of the total variance. PC2 is correlated most strongly with the VMA ratio across all axes, sedentary time (less-affected side), and percentage in sedentary time (less-affected side), with an inverse correlation with average kilocalories per hour (both affected and less-affected side). These correlations indicate that PC2 represents the domain of magnitude ratio, sedentary time, and EE in actigraphy. The biplot visually portrays the segregation of these variables along these two PCs.