Banister (1991) developed the ‘training impulse’ (TRIMP) as a method to quantify training load. Banisters TRIMP takes into consideration the intensity of exercise as calculated by the heart rate (HR) reserve method and the duration of exercise. The mean HR for the training session is weighted according to the relationship between HR and blood lactate as observed during incremental exercise and then multiplied by the session duration.
TRIMP is calculated using the formula below:
time (mins) x ∆HR x y
t = duration (mins)
∆HR = fractional elevation in HR or HR reserve
y = weighting factor
The ∆HR is weighted in such a manner that it reflects the intensity of effort as a guard against giving a disproportionate importance to long durations of low intensity exercise compared with more intense exercise. The multiplying factor (y) weights the ∆HR according to the classically described increase in blood lactate in trained male and female subjects, respectively.
Banister used the TRIMP to model endurance performance by using the TRIMP as measure of training load from which he modelled the dose-response relationships with fitness and fatigue. Banister hypothesized that each training bout produced both a fatigue and a fitness impulse. Banister hypothesized that fatigue decays three times faster than fitness, hence training adaptation and enhanced performance. Performance at any given time is a result of the fitness level less the accrued fatigue. Morton et al (1990) modelled endurance performance for two athletes using Banisters TRIMP. These results gave Banisters TRIMP some credence.
The modelling conducted to date has focused on endurance athletes with long training schedules who need to optimize performance for a relatively short competition period from 1 day (e.g. marathon) to a few weeks (e.g. cycling tour). The modelling of performance in endurance sports (Morton, 1990) somewhat validates Banisters TRIMP. However the modelling process has been subject to modifications (Busso, 2003) for improvements in predictions. Pfieffer in his study comparing modelling processes provides a good review of this if it is of interest to you (read Pfieffer paper)
There are two major limitations in using Banisters TRIMP in intermittent sports such as soccer. Firstly the use of mean HR may not reflect the fluctuations in HR that occur during intermittent exercise. The mean exercise intensity in soccer matches has been widely reported to be around the anaerobic threshold at 85% of HRmax (Stolen, et al., 2005) but has also been reported to peak at intensities close to HRmax (Ascensao et al., 2008). Secondly, the use of generic equations for males and females implies that the gender is the only factor making athletes different and doesn’t necessarily take into consideration individual differences that effect training load that the Impellizzeri et al (2005) model implies.
ASCENSAO, A., REBELO, A., OLIVEIRA, E., MARQUES, F., PEREIRA, L. & MAGALHAES, J. 2008. Biochemical impact of a soccer match - analysis of oxidative stress and muscle damage markers throughout recovery. Clinical Biochemistry, 41, 841-851.
BANISTER, E. W. 1991. Modeling Elite Athletic Performance. In: MACDOUGALL, J. D., WENGER, H. A. & GREEN, H. J. (eds.) Physiological Testing of Elite Athletes. Champaign, Illinois: Human Kinetics.
BUSSO, T. 2003. Variable dose-response relationship between exercise training and performance. Med Sci Sports Exerc, 35, 1188-95.
IMPELLIZZERI, F. M., RAMPININI, E. & MARCORA, S. M. 2005. Physiological assessment of aerobic training in soccer. J Sports Sci, 23, 583-592.
MORTON, R. H. 1990. Modeling human power and endurance. J Math Biol, 28, 49-64.
STOLEN, T., CHAMARI, K., CASTAGNA, C. & WISLOFF, U. 2005. Physiology of soccer - An update. Sports Medicine, 35, 501-536.