Table 1.
Characteristics of each group (mean±SD) and statistical differences between groups.
Figure 1.
Examples of PA patterns represented as symbolic/numerical sequences (left panel) or color barcodes (right panel)
: (A) and (B) have a similar distribution of states but differ in their sequential structure. The pattern shown in (C) differs from (A) and (B) by both, the distribution/variety of states and their sequential structure.
Table 2.
Mapping physical activity dimensions into physical activity states (PAS): the various physical activity (PA) dimensions i.e. the type (Sitting/Lying→Ly/Si, Standing→St, Walking→Wk), intensity (trunk acceleration norm→IaI, walking cadence→cad) and duration (d) are combined to generate PA states (PAS) that are encoded into numerical symbols using the alphabet Ω18 = [1,2,3,…,18] of length α = 18.
Figure 2.
Examples of PA barcodes recorded in two aged-matched subjects: a chronic pain patient (A) and a healthy pain free subject (B):
the two barcodes differ in both, the variety of PA states and their temporal distribution. The suggestion is that the chronic pain patient was not able to dynamically alternate between various body movements/activities, probably because of pain intensity and/or other factors such as fear of movement and activity avoidance.
Figure 3.
Metrics characterizing PA barcode (mean±SD)
: structural-static complexity quantified by normalized information entropy (Hn), (A); structural-dynamic complexity quantified by Sample entropy (SampEn) and Lempel-Ziv complexity (LZC), (B), (C); classical PA metric quantifying the percent of time spent in activity (walking and standing, i.e. PAS = 3 to 18) (D); composite deterministic score (CDS) which integrates all defined metrics (E).
Figure 4.
Correlations between metrics characterizing PA barcode.
Figure 5.
Receiver operator characteristics (ROC) curves and area under the curve (AUC) for the composite deterministic score (CDS) and the composite statistical score (CSS):
No Pain, vs. Severe Pain in the Middle Age groups (A) and Moderate Pain vs. Severe Pain in the Old Age groups (B).
Figure 6.
Quantitative assessment of intense physical activity states, PAS (mean±SD)
: No Pain vs. Severe Pain in the Middle Age groups (A) and Moderate Pain vs. Severe Pain in the Old Age groups (B). These results indicated that elderly with either low pain or high pain levels are not able to perform very intense activities.