Where
p_{t} is the performance at any time
t,
p_{0} is the initial performance,
k_{a} and
k_{f} (or
k_{1} and
k_{2}) are gain terms relating the magnitudes of the positive adaptive and negative fatigue effects (and also serving to convert the units used to quantify training to the units used to quantify performance),
τ_{a} and
τ_{f} (or
τ_{1} and
τ_{2}) are time constants describing the rate of decay of the positive adaptive and negative fatigue effects, and
w_{s} is the daily dose of training. The model therefore has four adjustable parameters, i.e.,
k_{a} and
k_{f} (or
k_{1} and
k_{2}) and
τ_{a} and
τ_{f} (or
τ_{1} and
τ_{2}), which are constrained such that
k_{a}<
k_{f} (or
k_{1}<
k_{2}) and
τ_{a}>
τ_{f} (or
τ_{1}>
τ_{2}).