Can measures of critical power precisely estimate the maximal metabolic steady-state?
Critical power (CP) conceptually represents the highest power output (PO) at physiological steady-state. In cycling exercise, CP is traditionally derived from the hyperbolic relationship of ∼5 time-to-exhaustion trials (TTE) (CPHYP). Recently, a 3-min all-out test (CP3MIN) has been proposed for estimation of CP as well the maximal lactate steady-state (MLSS). The aim of this study was to compare the POs derived from CPHYP, CP3MIN, and MLSS, and the oxygen uptake and blood lactate concentrations at MLSS. Thirteen healthy young subjects (age, 26 ± 3years; mass, 69.0 ± 9.2 kg; height, 174 ± 10 cm; maximal oxygen uptake, 60.4 ± 5.9 mL·kg-1·min-1) were tested. CPHYPwas estimated from 5 TTE. CP3MINwas calculated as the mean PO during the last 30 s of a 3-min all-out test. MLSS was the highest PO during a 30-min ride where the variation in blood lactate concentration was ≤ 1.0 mmol·L-1during the last 20 min. PO at MLSS (233 ± 41 W; coefficient of variation (CoV), 18%) was lower than CPHYP(253 ± 44 W; CoV, 17%) and CP3MIN(250 ± 51 W; CoV, 20%) (p < 0.05). Limits of agreement (LOA) from Bland-Altman plots between CPHYPand CP3MIN(-39 to 31 W), and CP3MINand MLSS (-29 to 62 W) were wide, whereas CPHYPand MLSS presented the narrowest LOA (-7 to 48 W). MLSS yielded not only the maximum PO of stable blood lactate concentration, but also stable oxygen uptake. In conclusion, POs associated to CPHYPand CP3MINwere larger than those observed during MLSS rides. Although CPHYPand CP3MINwere not different, the wide LOA between these 2 tests and the discrepancy with PO at MLSS questions the ability of CP measures to determine the maximal physiological steady-state.
a Faculty of Kinesiology, University of Calgary, Calgary, AB T2N 1N4, Canada.
Felipe
F
Mattioni Maturana
b School of Kinesiology, The University of Western Ontario, London, ON, N6A 3K7 Canada.
Daniel A
DA
Keir
b School of Kinesiology, The University of Western Ontario, London, ON, N6A 3K7 Canada.
Kaitlin M
KM
McLay
a Faculty of Kinesiology, University of Calgary, Calgary, AB T2N 1N4, Canada.
Juan M
JM
Murias
D000328:Adult; D054874:Athletic Performance; D001642:Bicycling; D004734:Energy Metabolism; D005080:Exercise Test; D017079:Exercise Tolerance; D005221:Fatigue / Q000097:blood / Q000209:etiology / Q000378:metabolism; D005260:Female; D000072696:High-Intensity Interval Training; D006801:Humans; D019344:Lactic Acid / Q000097:blood; D008297:Male; D018482:Muscle, Skeletal / Q000502:physiology*; D010101:Oxygen Consumption; D005082:Physical Exertion; D010809:Physical Fitness; D015203:Reproducibility of Results; D013997:Time Factors; D055815:Young Adult
D019344:Lactic Acid
3-min all-out; exercise-intensity thresholds; lactate maximal en régime stable; maximal lactate steady-state; power-time relationship; relation puissance-temps; seuils d’intensité de l’exercice; test maximal de 3 min