Measuring maximum oxygen uptake with an incremental swimming test and by chasing rainbow trout to exhaustion inside a respirometry chamber yields the same results

摘要

This study hypothesized that oxygen uptake (& x1e40;O-2) measured with a novel protocol of chasing rainbow troutOncorhynchus mykissto exhaustion inside a static respirometer while simultaneously monitoring & x1e40;O-2(& x1e40;O-2chase) would generate the same and repeatable peak value as when peak active & x1e40;O-2(& x1e40;O-2active) is measured in a critical swimming speed protocol. To reliably determine peak & x1e40;O-2chase, and compare to the peak during recovery of & x1e40;O(2)after a conventional chase protocol outside the respirometer (& x1e40;O-2rec), this study applied an iterative algorithm and a minimum sampling window duration (i.e., 1 min based on an analysis of the variance in background and exercise & x1e40;O-2) to account for & x1e40;O(2)dynamics. In support of this hypothesis, peak & x1e40;O-2active(707 +/- 33 mg O(2)h(-1)kg(-1)) and peak & x1e40;O-2chase(663 +/- 43 mg O(2)h(-1)kg(-1)) were similar (P= 0.49) and repeatable (Pearson's and Spearman's correlation test;r >= 0.77;P < 0.05) when measured in the same fish. Therefore, estimates of & x1e40;O(2max)can be independent of whether a fish is exhaustively chased inside a respirometer or swum to fatigue in a swim tunnel, provided & x1e40;O(2)is analysed with an iterative algorithm and a minimum but reliable sampling window. The importance of using this analytical approach was illustrated by peak & x1e40;O(2chase)being 23% higher (P < 0.05) when compared with a conventional sequential interval regression analysis, whereas using the conventional chase protocol (1-min window) outside the respirometer increased this difference to 31% (P < 0.01). Moreover, because peak & x1e40;O(2chase)was 18% higher (P < 0.05) than peak & x1e40;O-2rec, chasing a fish inside a static respirometer may be a better protocol for obtaining maximum & x1e40;O-2.