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Inter‐individual oxygen delivery differences strongly influence estimated critical power in an all out exercise test
Author(s) -
Kellawan Jeremy Mikhail,
Bravo Michael F,
Moynes Jackie S,
Bentley Robert,
Shantz Rebecca,
Tschakovsky Michael E
Publication year - 2011
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.25.1_supplement.1023.3
Subject(s) - forearm , supine position , brachial artery , vasodilation , pulse oximetry , medicine , oxygen saturation , cardiology , anesthesia , oxygen , chemistry , surgery , blood pressure , organic chemistry
PURPOSE To determine if differences in O 2 delivery (O 2 D) between healthy subjects predicts performance in a critical power (CP) test. METHODS 10 healthy male subjects lay supine with the arm at heart level and completed 10 min of rhythmic maximal voluntary contractions (1 s contraction: 2 s relaxation duty cycle). CP was calculated as the average peak contraction force during the last 30 s of the trial where force plateaued. Forearm brachial artery blood flow (FBF) during exercise (echo and Doppler ultrasound) and O 2 D (FBF x arterial oxygen content ([haemoglobin] from venous blood sample and oxygen saturation from pulse oximetry)) were measured. RESULTS means ± SD. A wide range of O 2 D and CP was observed. O 2 D 101.5 ± 25.1 ml O 2 /min (range 70.92–154.1 ml O 2 /min) & CP 25.4 ± 6.0 kg (range 17.5–34.7 kg). O 2 D & FBF area under the curve (AUC, ml O 2 /forearm volume & ml/forearm volume) for the first 200 s of exercise were predictors of CP (r 2 = 0.47, 0.48 p ≤ 0.03). However, O 2 D & FBF total AUC during exercise was the strongest predictors rather than steady state levels achieved (r 2 = 0.63, 0.66 p ≤ 0.01). CONCLUSIONS Considerable inter‐individual differences in oxygen delivery exist during an all out CP test. These differences account for much of the inter‐individual differences in CP, supporting the contention that vasodilatory responsiveness and capacity are important determinants of small muscle mass CP. NSERC