# W′ reconstitution modelling during intermittent exercise performed to task failure

## TL;DR

This study shows that individualized models are needed to accurately predict cycling performance during high-intensity intermittent exercise.

## Contribution

The study introduces individualized W′ reconstitution modeling for better prediction of intermittent cycling performance.

## Key findings

- Standard W′ reconstitution equations failed to predict exhaustion during intermittent exercise.
- Individualized τW′ equations showed stronger correlations with endurance performance metrics like lactate threshold and critical power.
- W′ rec is primarily influenced by aerobic parameters such as lactate threshold and critical power.

## Abstract

W′ balance (W′BAL) modelling is becoming an important tool to monitor intermittent cycling performance. This study assessed the ability of different time constant (τW′) equations for W′ reconstitution (W′rec) to predict exhaustion during intermittent exercise and the relationship between parameters of W′rec with established determinants of endurance performance.

Thirteen cyclists performed cycling performance tests to determine: lactate threshold (LT), critical power (CP), W′, V̇O2max, maximal aerobic power (MAP) and maximal sprint power (Pmax). Participants subsequently performed three intermittent Wʹ depletion trials to volitional exhaustion involving different work and recovery periods: 20:10; 3 × 20 s intervals separated by 10 s recoveries before a final continuous effort, 60:30; 3 × 60 s intervals separated by 30 s recoveries before a final continuous effort, 20:10TE; repeated 20 s intervals each separated by 10 s recoveries. W′BAL was determined via five different τW′ equations and an individualised equation (τW′INDV) calculated from the 20:10TE under the assumption that the point of task failure represents 0 kJ.

Current τW′ equations failed to predict exhaustion during intermittent exercise protocols to exhaustion. Total work done above CP for the 20:10TE (Wʹtotal20:10TE) was positively correlated with absolute and relative LT, CP, V̇O2max, MAP, and Pmax (r = 0.64–0.80; P < 0.05). The τW′INDV was negatively correlated with relative CP (r = − 0.69), and LT1 (r = − 0.58), and Wʹtotal20:10TE (r = − 0.63).

Individualised τW′ should be utilised for the accurate prediction of WʹBAL. W′rec is influenced primarily by aerobic performance parameters, including LT1 and CP.