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  • Author: Anni Vanhatalo x
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Anni Vanhatalo, Andrew M. Jones and Mark Burnley

The critical power (CP) is mathematically defined as the power-asymptote of the hyperbolic relationship between power output and time-to-exhaustion. Physiologically, the CP represents the boundary between the steady-state and nonsteady state exercise intensity domains and therefore may provide a more meaningful index of performance than other well-known landmarks of aerobic fitness such as the lactate threshold and the maximal O2 uptake. Despite the potential importance to sports performance, the CP is often misinterpreted as a purely mathematical construct which lacks physiological meaning and only in recent years has this concept begun to emerge as valid and useful technique for monitoring endurance fitness. This commentary defines the basic principles of the CP concept, outlines its importance to high-intensity exercise performance, and provides an overview of the current methods available for its assessment. Interventions including training, pacing and prior exercise can be used to alter the parameters of the power-time relationship. A future challenge lies in optimizing such interventions in order to positively affect the parameters of the power-time relationship and thereby enhance sports performance in specific events.

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Philip F. Skiba, David Clarke, Anni Vanhatalo and Andrew M. Jones

Recently, an adaptation to the critical-power (CP) model was published, which permits the calculation of the balance of the work capacity available above the CP remaining (Wbal) at any time during intermittent exercise. As the model is now in use in both amateur and elite sport, the purpose of this investigation was to assess the validity of the Wbal model in the field. Data were collected from the bicycle power meters of 8 trained triathletes. Wbal was calculated and compared between files where subjects reported becoming prematurely exhausted during training or competition and files where the athletes successfully completed a difficult assigned task or race without becoming exhausted. Calculated Wbal was significantly different between the 2 conditions (P < .0001). The mean Wbal at exhaustion was 0.5 ± 1.3 kJ (95% CI = 0–0.9 kJ), whereas the minimum Wbal in the nonexhausted condition was 3.6 ± 2.0 kJ (95% CI = 2.1–4.0 kJ). Receiver-operator-characteristic (ROC) curve analysis indicated that the Wbal model is useful for identifying the point at which athletes are in danger of becoming exhausted (area under the ROC curve = .914, SE .05, 95% CI .82–1.0, P < .0001). The Wbal model may therefore represent a useful new development in assessing athlete fatigue state during training and racing.

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Stephen J. Bailey, Anni Vanhatalo, Matthew I. Black, Fred J. DiMenna and Andrew M. Jones

Purpose:

To assess whether combining prior “priming” exercise with an all-out pacing strategy is more effective at improving oxygen-uptake (V̇O2) kinetics and cycling performance than either intervention administered independently.

Methods:

Nine men completed target-work cycling performance trials using a self-paced or all-out pacing strategy with or without prior severe-intensity (70%Δ) priming exercise. Breath-by-breath pulmonary V̇O2 and cycling power output were measured during all trials.

Results:

Compared with the self-paced unprimed control trial (22 ± 5 s), the V̇O2 mean response time (MRT) was shorter (V̇O2 kinetics were faster) with all-out pacing (17 ± 4 s) and priming (17 ± 3 s), with the lowest V̇O2 MRT observed when all-out pacing and priming were combined (15 ± 4 s) (P < .05). However, total O2 consumed and end-exercise V̇O2 were only higher than the control condition in the primed trials (P < .05). Similarly, cycling performance was improved compared with control (98 ± 11 s) in the self-paced primed (93 ± 8 s) and all-out primed (92 ± 8 s) trials (P < .05) but not the all-out unprimed trial (97 ± 5 s; P > .05).

Conclusions:

These findings suggest that combining an all-out start with severe-intensity priming exercise additively improves V̇O2 MRT but not total O2 consumption and cycling performance since these were improved by a similar magnitude in both primed trials relative to the self-paced unprimed control condition. Therefore, these results support the use of priming exercise as a precompetition intervention to improve oxidative metabolism and performance during short-duration high-intensity cycling exercise, independent of the pacing strategy adopted.

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Kirsty Brock, Prokopios Antonellis, Matthew I. Black, Fred J. DiMenna, Anni Vanhatalo, Andrew M. Jones and Stephen J. Bailey

Purpose: To investigate whether oxygen-uptake (V˙O2) kinetics and simulated 4-km cycling performance are synergistically improved by prior “priming” exercise and an all-out starting strategy. Methods: Nine men completed 4 target work trials (114 ± 17 kJ) to assess V˙O2 kinetics and cycling performance in a repeated-measures, crossover experimental design. Trials were initiated with either a 12-s all-out start or a self-selected start and preceded by prior severe-intensity (70%Δ) priming exercise or no priming exercise. Results: The V˙O2 mean response time (MRT) was lower (indicative of faster V˙O2 kinetics) in the all-out primed condition (20 ± 6 s) than in the all-out unprimed (23 ± 6 s), self-paced-unprimed (42 ± 13 s), and self-paced-primed (42 ± 11 s) trials (P < .05), with the V˙O2 MRT also lower in the all-out unprimed than the self-paced unprimed and self-paced primed trials (P < .05). Trial-completion time was shorter (performance was enhanced) in the all-out primed trial (402 ± 14 s) than in the all-out unprimed (408 ± 14 s), self-paced unprimed (411 ± 16 s), and self-paced primed (411 ± 19 s) trials (P < .05), with no differences between the latter 3 trials. Conclusions: The findings from this study suggest that combining severe-intensity priming exercise with a short-duration all-out starting strategy can expedite the adjustment of V˙O2 and lower completion time during a cycling performance trial to a greater extent than either intervention administered independently. These results might have implications for optimizing performance in short-duration high-intensity competitive events such as a 4-km cycling time trial.