8/14/2019 Limitations of Incremental Tests in Performance Testing (PR)

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Limitations of incremental tests in performance testing – unstable lactateand oxygen kinetics at higher workloads

P Reynolds, B Donne

Deparment of Physiology, Trinity College Dublin

Introduction: Incremental exercise tests are considered the ‘gold standard’ for performanceevaluation and estimation of lactate threshold (LT). Their accuracy relies on the assumption of 

steady O2 and lactate kinetics at the end of each workload segment. Both oxygen uptake (  O2)and blood lactate concentration (BLa) show increases over time above theoretical ‘threshold’questioning the validity of this assumption

1,2. This study sought to assess the effects of the time

dependent component of   O2 and BLa on each other.

Methods: Nine male cyclists participated in this study. Cyclists were medically cleared prior toparticipation and performed a graded incremental test to volitional exhaustion to determine

maximum power (Pmax) and LT. Their HR,   O2 and BLa were recorded at regular intervals.Subsequently on separate days four 30 minute steady state tests were performed at workloads

equivalent to 90%LT, LT, LT+25%δ and LT+50%δ     where (δ=Pmax-LT). Rates of increase of BLa

(dBLa/dt) and   O2 (d  O2/dt) were computed.

Results: 1F-RM Anova detected significantly larger mean dBLa/dt and d  O2/dt in the LT+50%protocol only; 0.393±0.085mmol.L

-1.min

-1and 0.5±0.11mL.kg

-1.min

-2respectively (P <0.01).

Significant correlation was detected between mean dBLa/dt and mean d  O2/dt for test LT+50%δ 

(r=0.81). 2F-RM Anova performed on data from 90%LT, LT and LT+25%δ tests detected

significant interaction of time and exercise intensity on dBLa/dt throughout each test and on

d  O2/dt during the first 6min. Occurrence of max dBLa/dt and max d  O2/dt were typically morethan 3min apart.

Discussion: These results demonstrated that dBLa/dt at a particular exercise intensity is timedependent and that dBLa/dt at a particular time is exercise intensity dependent. This, together with the fact that there was a significant time delay between a recorded oxygen deficit and anincrease in BLa, would suggest that further investigation be done into the appropriate duration of each exercise segment during incremental tests. The results of this study would also support theaddition of repeated steady state tests to conventional incremental testing to improve accuracy of estimations involving BLa.

1: Whipp BJ & Wasserman K (1972). Oxygen uptake for various intensities of constant-loadexercise. J Appl Physiol  33, 351–356.

2: Beneke R. (2003). Methodological aspects of maximal lactate steady state - implications for performance testing. Eur J App Physiol  89, 95-99