Reliability of forearm oxygen uptake during handgrip exercise : assessment by ultrasonography and venous blood gas

Abstract

Assessment of forearm oxygen uptake (O2) during handgrip exercise is a keenly investigated concept for observing small muscle mass metabolism. Although a combination of Doppler ultrasound measurements of brachial artery blood flow () and blood gas drawn from a deep forearm vein has been utilized to calculate forearm O2 for more than two decades, the applicability of this experimental design may benefit from a thorough evaluation of its reliability during graded exercise. Therefore, we evaluated the reliability of this technique during incremental handgrip exercise in ten healthy young (24&nbsp;±&nbsp;3(SD) years.) males. O2 and work rate (WR) exhibited a linear relationship (1.0&nbsp;W: 43.8&nbsp;±&nbsp;10.1&nbsp;mL·min−1; 1.5&nbsp;W: 53.8&nbsp;±&nbsp;14.1&nbsp;mL·min−1; 2.0&nbsp;W: 63.4&nbsp;±&nbsp;16.3&nbsp;mL·min−1; 2.5&nbsp;W: 72.2&nbsp;±&nbsp;17.6&nbsp;mL·min−1; 3.0&nbsp;W: 79.2&nbsp;±&nbsp;18.6&nbsp;mL·min−1; r&nbsp;=&nbsp;0.65, P&nbsp;<&nbsp;0.01). In turn, O2 was strongly associated with (1.0&nbsp;W: 359&nbsp;±&nbsp;86&nbsp;mL·min−1; 1.5&nbsp;W: 431&nbsp;±&nbsp;112&nbsp;mL·min−1; 2.0&nbsp;W: 490&nbsp;±&nbsp;123&nbsp;mL·min−1; 2.5&nbsp;W: 556&nbsp;±&nbsp;112&nbsp;mL·min−1; 3.0&nbsp;W: 622&nbsp;±&nbsp;131&nbsp;mL·min−1; r&nbsp;=&nbsp;0.96; P&nbsp;<&nbsp;0.01), whereas arteriovenous oxygen difference (a‐vO2diff) remained constant following all WRs (123&nbsp;±&nbsp;11–130&nbsp;±&nbsp;10&nbsp;mL·L−1). Average O2 test–retest difference was −0.4&nbsp;mL·min−1 with ±2SD limits of agreement (LOA) of 8.4 and −9.2&nbsp;mL·min−1, respectively, whereas coefficients of variation (CVs) ranged from 4–7%. Accordingly, test–retest difference was 11.9&nbsp;mL·min−1 (LOA: 84.1&nbsp;mL·min−1; −60.4&nbsp;mL·min−1) with CVs between 4 and 7%. Test–retest difference for a‐vO2diff was −0.28&nbsp;mL·dL−1 (LOA: 1.26mL·dL−1; −1.82&nbsp;mL·dL−1) with 3–5% CVs. In conclusion, our results revealed that forearm O2 determination by Doppler ultrasound and direct venous sampling is linearly related to WR, and a reliable experimental design across a range of exercise intensities.