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Title: Estimation of anaerobic capacity : practical limitations and physiological assumptions
Author: Muniz-Pumares, Daniel
ISNI:       0000 0004 5923 8507
Awarding Body: University of Surrey
Current Institution: St Mary's University, Twickenham
Date of Award: 2016
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High-intensity exercise necessitates simultaneous aerobic and anaerobic ATP resynthesis. Unfortunately, direct quantification of the finite amount of energy derived from the anaerobic energy system (i.e. anaerobic capacity; AnC) is challenging and not practical on a daily basis. Instead, there are two approaches to estimate AnC: the accumulated oxygen deficit (AOD) and the curvature constant of the power-duration relationship (W'), both of which rely on several assumptions. First, determination of AOD requires an estimation of supramaximal oxygen demand, typically from the projection of the oxygen uptake (V̇O2)-power output relationship determined from various submaximal exercise intensites assuming a linear relationship. From a practical perspective, AOD is a time-consuming protocol. Secondly, W' is considered to represent anaerobic work capacity and correlates with AOD. Moreover, both AOD and W' are assumed to remain constant irrespective of pacing strategies and/or changes in oxygen availability. The overarching aim of this PhD was to investigate the assumptions and practical limitations surrounding AOD and W' as tests to estimate AnC. Study 1 investigated the linearity of the V̇O2-power output relationship during exercise below vs. above the lactate threshold. Ten cyclists completed consecutive 3 min bouts of exercise below and above the lactate threshold. The V̇O2-power output relationship remained constant up to intensities of ~95% maximal V̇O2 (V̇O2max). Study 2 determined whether AOD remains constant during exercise to exhaustion at any supramaximal intensity. Twenty-one cyclists performed a constant work-rate (CWR) exercise bout to exhaustion at 105, 112.5, 120 and 127.5% V̇O2max. Compared to 112.5% V̇O2max, AOD was lower at 105 and 127% V̇O2max, but there were no differences between 112.5 and 120% V̇O2max. At 112.5% V̇O2max, the coefficient of variation of AOD was 8.7%. Study 3 determined whether AOD can be calculated in a single-day trial. Twenty cyclists performed CWR tests at 112.5% V̇O2max 25 min after submaximal and maximal tests (single-day AOD), and after no prior exercise (traditional AOD). Single-day AOD was reduced by 17% compared to traditional AOD, suggesting that a single-day approach is untenable. Study 4 established the relationship between AOD and W', and whether CWR and 3-min all-out (3AO) tests affected i) the strength of the relationship and ii) the magnitude of AOD and W'. Both measures were correlated during CWR (r = 0.654) and 3AO (r = 0.664) tests. However, AOD was greater in CWR tests, whereas W' was greater in 3AO tests. Study 5 determined whether AOD and W' were affected by hypoxia or hyperoxia during CWR and 3AO tests. AOD was determined during CWR and 3AO tests in 10 cyclists in hypoxia (15% oxygen), normoxia (21% oxygen) and hyperoxia (35% oxygen). There was no effect of environmental conditions on AOD, but CWR tests resulted in higher AOD than 3-min all-out tests. In contrast, there was no effect of environmental condition or pacing on W'. In conclusion, using 3 min stages to construct the V̇O2-power output relationship, the AOD reaches its maximum during a CWR test to exhaustion at 112.5-120% V̇O2max, with a test-retest coefficient of variation of 8.7%. However, the magnitude of AOD is not consistent, as 3AO tests resulted in a reduced AOD. Moreover, using this protocol, two trials are needed to determine AOD. The magnitude of W' provides an indication of AnC, given that AOD and W' were strongly correlated. W' is a solid construct, and remains constant irrespective of pacing and changes in oxygen availability. Although W' is likely determined by other factors besides AnC, it appears to be a favourable option to estimate anaerobic energy production.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: 571 Physiology & related subjects ; 796 Athletic & outdoor sports & games