Prior upper body exercise reduces the curvature constant (W′) of the hyperbolic power-duration relationship without affecting critical power. This study tested the hypothesis that prior upper body exercise reduces the work done over the end-test power (WEP; analogue of W′) during a 3-min all-out cycling test (3MT) without affecting the end-test power (EP; analogue of critical power).
Ten endurance-trained men (V˙O2max = 62 ± 5 mL⋅kg-1⋅min-1) performed a 3MT without (CYC) and with (ARM-CYC) prior severe-intensity, intermittent upper body exercise. EP was calculated as the mean power output over the last 30-s of the 3MT, whereas WEP was calculated as the power-time integral above EP.
At the start of the 3MT, plasma [La-] (1.8 ± 0.4 vs. 14.1 ± 3.4 mmol·L-1) and [H+] (42.8 ± 3.1 vs. 58.6 ± 5.5 nmol·L-1) were higher, whereas the strong ion difference ([SID]) (41.4 ± 2.2 vs. 30.9 ± 4.6 mmol·L-1) and [HCO3-] (27.0 ± 1.9 vs. 16.9 ± 3.2 mmol·L-1) were lower, during ARM-CYC than CYC (P < 0.010). EP was 12% lower during the 3MT of ARM-CYC (298 ± 52 W) than CYC (338 ± 60 W) (P < 0.001), whereas WEP was not different (CYC: 12.8 ± 3.3 kJ vs. ARM-CYC: 13.5 ± 4.1 kJ, P = 0.312). EP in CYC was positively correlated with the peak [H+] (r = 0.78, P = 0008), and negatively correlated with the lowest [HCO3-] (r = -0.74, P = 0.015).
These results suggest that EP during a 3MT in endurance-trained men is sensitive to fatigue-related ionic perturbation.