TABLE 2.
Associations between TSI, tissue saturation index; changes during exercise and indices of post-occlusive reactive hyperaemia (PORH); measured in the lower-limb skeletal muscle. ∆TSIBL-EE is the change in tissue saturation index (TSI); between rest (baseline, BL) and the EE, end of exercise ; ∆TSIINC-MIN is the change in TSI from it is highest point at the INC, increment; to it is MIN, minimum; ∆TSIBL-INC is the change in TSI from the BL to the highest point (INC). unadj, Unadjusted; and adjusted β-coefficients, 95% confidence intervals and p-values are presented for each association. M1a, Model 1a; is adjusted for age, sex, ethnicity, the duration of the ischaemic stimulus and the estimated workload achieved during the stepping test. M1b, Model 1b; is adjusted for age, sex, ethnicity and the duration of the ischaemic stimulus. M2, Model 2; is adjusted for age, sex, ethnicity, mean arterial pressure (MAP); change at the start of exercise.
| Β-coefficient (95%CI) p-value | |||||||
|---|---|---|---|---|---|---|---|
| ∆TSIBL-EE | ∆TSIINC-MIN | ∆TSIBL-INC | |||||
| NIRS measure of PORH | Unadj. (n = 149) | M1a (n = 149) | Unadj. (n = 149) | M1a (n = 149) | Unadj. (n = 129) | M1b (n = 129) | M2 (n = 129) |
| Time to 50% PORH (s) | 0.20 (−0.09, 0.49) 0.169 | 0.14 (−0.17, 0.44) 0.366 | 0.06 (−0.25, 0.36) 0.720 | −0.01 (−0.33, 0.31) 0.935 | −0.25 (−0.42, 0.07) 0.006 | −0.19 (−0.37, 0.006) 0.043 | −0.18 (−0.36, 0.005) 0.056 |
| Time to 95% PORH (s) | 0.09 (0.008, 0.17) 0.031 | 0.08 (−0.01, 0.17) 0.085 | 0.02 (−0.07, 0.10) 0.683 | −0.003 (−0.09, 0.10) 0.945 | −0.09 (−0.13, 0.04) 0.001 | −0.07 (−0.12, 0.02) 0.009 | −0.07 (−0.12, 0.02) 0.012 |
| Time to 100% PORH (s) | 0.05 (0.01, 0.08) 0.009 | 0.05 (0.01, 0.09) 0.012 | −0.002 (−0.04, 0.04) 0.937 | 0.003 (−0.04, 0.04) 0.903 | −0.04 (−0.06, 0.02) 0.001 | −0.03 (−0.05, 0.004) 0.024 | −0.03 (−0.05, 0.003) 0.028 |
| Recovery rate PORH (1/s) | −47 (−81, 13) 0.006 | −47 (−85, 9.9) 0.014 | −11 (−48, 25) 0.538 | −9.8 (−49.6, 29.9) 0.626 | 20 (−0.88, 40.7) 0.060 | 8.3 (−14, 31) 0.468 | 7.2 (−15.4, 29.9) 0.530 |
| (log)AUC PORH (µM x s) | 1.6 (0.62, 2.6) 0.002 | 1.7 (0.62, 2.8) 0.002 | 1.5 (0.45, 2.5) 0.005 | 1.6 (0.45, 2.7) 0.007 | 0.68 (0.06, 1.3) 0.032 | 0.80 (0.14, 1.5) 0.018 | 0.85 (0.18, 1.5) 0.013 |
| ∆OxyHb PORH (µM) | 0.05 (0.02, 0.10) 0.042 | 0.04 (0.002, 0.108) 0.041 | 0.08 (0.03, 0.13) 0.003 | 0.08 (0.03, 0.13) 0.004 | 0.06 (0.03, 0.09) <0.001 | 0.06 (0.02, 0.07) 0.001 | 0.05 (0.02, 0.09) 0.001 |