trackeR (version 1.5.2)

# Wprime: W': work capacity above critical power/speed.

## Description

W': work capacity above critical power/speed.

## Usage

Wprime(object, session = NULL, quantity = c("expended", "balance"), w0,
cp, version = c("2015", "2012"), meanRecoveryPower = FALSE,
parallel = FALSE, ...)

## Arguments

object

A trackeRdata object.

session

A numeric vector of the sessions to be used, defaults to all sessions.

quantity

Should W' 'expended' or W' 'balance' be returned?

w0

Inital capacity of W', as calculated based on the critical power model by Monod and Scherrer (1965).

cp

Critical power/speed, i.e., the power/speed which can be maintained for longer period of time.

version

How should W' be replenished? Options include '2015' and '2012' for the versions presented in Skiba et al. (2015) and Skiba et al. (2012), respectively. See Details.

meanRecoveryPower

Should the mean of all power outputs below critical power be used as recovery power? See Details.

parallel

Logical. Should computation be carried out in parallel? If TRUE computation is performed in parallel using the backend provided to foreach. Default is FALSE.

...

Currently not used.

## Value

An object of class trackeRWprime.

## Details

#' Skiba et al. (2015) and Skiba et al. (2012) both describe an exponential decay of $$W'$$ expended over an interval $$[t_{i-1}, t_i)$$ if the power output during this interval is below critical power:

$$W_exp (t_i) = W_exp(t_{i-1}) * exp(nu * (t_i - t_{i-1}))$$

However, the factor nu differs: Skiba et al. (2012) describe it as $$1/\tau$$ with $$\tau$$ estimated as

$$tau = 546 * exp(-0.01 * (CP - P_i)) + 316$$

Skiba et al. (2015) use $$(P_i - CP) / W'_0$$. Skiba et al. (2012) and Skiba et al. (2015) employ a constant recovery power (calculated as the mean over all power outputs below critical power). This rationale can be applied by setting the argument meanRecoveryPower to TRUE. Note that this uses information from all observations with a power output below critical power, not just those prior to the current time point.

## References

Monod H, Scherrer J (1965). 'The Work Capacity of a Synergic Muscular Group.' Ergonomics, 8(3), 329--338.

Skiba PF, Chidnok W, Vanhatalo A, Jones AM (2012). 'Modeling the Expenditure and Reconstitution of Work Capacity above Critical Power.' Medicine & Science in Sports & Exercise, 44(8), 1526--1532.

Skiba PF, Fulford J, Clarke DC, Vanhatalo A, Jones AM (2015). 'Intramuscular Determinants of the Abilility to Recover Work Capacity above Critical Power.' European Journal of Applied Physiology, 115(4), 703--713.

## Examples

# NOT RUN {
data('runs', package = 'trackeR')
wexp <- Wprime(runs, session = c(11,13), cp = 4, version = '2012')
plot(wexp)
# }