Sensitivity of forearm critical power to acute manipulation of perfusion pressure

PURPOSEWe tested the hypothesis that manipulating perfusion pressure (PP) impacts forearm critical power (fCP).METHODS9 healthy young (23 ± 2.6 yrs) males completed 10 min fCP tests in each of arm above (A) and below (B) heart level (forearm PP A < B by ~30 mmHg). fCP (average of force impulse in last 30 s of test), forearm blood flow (FBF; echo and Doppler ultrasound), arterial pressure (MAP; finger photoplethysmography), O2 consumption (VO2; venous blood samples, Fick eqn) were measured during exercise.RESULTSmean ± SD. Responders (all with compromised fCP in A vs. B; 21 ± 7 vs. 30 ± 6 kg·s, p=0.01) and non‐responders (no compromise to fCP in A vs. B; 29 ± 17 vs. 27 ± 16 kg·s, P=0.14) were identified. Responders exhibited O2D compromise in A vs. B (164 ± 60 vs. 178 ± 65 ml O2/min, p=0.04), and all had lower VO2 in A vs. B but this was not statistically significant (VO2 88 ± 30 ml/min vs. 104 ± 40 ml/min, p=0.12). Non‐responders had no compromise to O2D in A vs. B (153 ± 26 vs. 164 ± 28 ml O2/min, p=0.53), nor any compromise to VO2 (99 ± 21 ml/min vs. 106 ± 28 ml/min, p=0.58). No clear pattern regarding pressor or vasodilatory compensation to protect O2D was found (Responders A vs. B, ΔFVC p=0.01, ΔMAP p=0.12; Non‐responders A vs. B ΔFVC p=0.22, ΔMAP p=0.37).CONCLUSIONSReductions in perfusion pressure can reduce forearm critical power in individuals who cannot defend O2D. These data highlight the importance of O2D to fCP. NSERC

Sensitivity of forearm critical power to acute manipulation of perfusion pressure Journal Articles