Ambient assisted living technologies for older adults with cognitive and physical impairments: a review.

PURPOSE: We investigated core body temperature (CBT) during a graded exercise test (GXT) in comparison with gas exchange dynamics.

METHODS

Thirty-two active males performed a treadmill GXT (0.5 km/h increments every 30 seconds, 1.5% incline) until exhaustion. Gas exchange data and rectal temperature (Tre) were continuously registered. Ten participants repeated the test for reliability assessment. The first and second gas exchange thresholds (VT1 and VT2) were determined by the simplified V-slope method, while CBT dynamics and eventual temperature thresholds (TT1 and TT2) were assessed according to the criteria defined in this study. Three independent evaluators determined gas exchange and temperature thresholds.

RESULTS

In 29 subjects, Tre increase was best fitted with a 3-phase segmented model of successively steeper slopes, with a linear relationship in all three segments (17 subjects), or in two segments, with a quadratic relationship for the remaining segment (12 subjects). The between-segment intersection points were considered as TT1 and TT2. In three participants, Tre was best fitted with a two-segment, single-breakpoint (TT1 or TT2) model. The evaluators' objectivity was satisfactory for VT1 (α = 0.786), very high for TT2 (α = 0.941) and VT2 (α = 0.948). TT1 and VT1 were moderately correlated (ρ = 0.41, p = 0.021) while VT2 and TT2 were highly correlated (r = 0.78, p < 0.001) showing a small, yet statistically significant difference (12.95 ± 1.9 vs 13.43 ± 1.7 km/h, p = 0.039). However, test-retest reliability was low.

CONCLUSION

The breakpoints in CBT increase observed during graded running may represent transitions between the three intensity domains of physical activity.