Stagno, Thatcher, and Van Someren (2007) developed a modified version of Banister’s TRIMP in an attempt to quantify training load for field hockey. Rather than use a generic equation to reflect a hypothetical blood lactate profile, these authors directly measured the blood lactate profile of the hockey players. The weightings they used therefore reflected the profile of a typical blood lactate response curve to increasing exercise intensity for the specific population, in this case the hockey team. While not truly individualized, their method used the mean blood lactate profile from all of the players to generate the weightings, providing at least some degree of individualisation. They then anchored five HR zones around the lactate threshold and OBLA, with the resulting zone weightings being 1.25, 1.71, 2.54, 3.61 and 5.16. The accumulated time in each HR zone was then multiplied by its respective zone weighting to derive an overall TRIMPmod. The research quantified the TL in hockey and established relationships between TRIMPmod and various fitness parameters during the course of a season.
They found the mean weekly TRIMPmod shared significant relationships with changes in running velocity at 4 mmol (vOBLA) and VO2max. They also reported significant correlations between time spent in high-intensity activity and the change in VO2max and the change in vOBLA. The results of this study suggest that TRIMPmod is a method by which TL could possibly be measured. The original TRIMP (Banister, 1991) is calculated using the mean HR for a particular exercise session or interval of training. Stagno, used time accumulated in zones to reflect the different intensities team sport players work at in comparison to endurance athletes may work at a similar internsity for longer periods. This may make the use of a mean HR more suitable and less of an issue in endurance athletes. But modern day training regimens with endurance athletes also use interval type approaches. Stagno didn't compare his method to Banisters and we do not know if there is any significant difference when using the zone method of Stagno compared to the mean HR method as used by Banister. The zones used by Stagno were based on the HR at lactate threshold (LT), defined as 1.5 mmol.L-1 and the onset of blood lactate accumulation (OBLA) defined as 4 mmol.L-1. They used the blood lactate responses at four different speeds from their player sample to create an equation for the weightings or the ‘Y’ value as defined by Banister. Zones 2 and 4 were created around the mean HR at LT and OBLA. A zone width of 7% fractional elevation was formed at these points. Zones 1, 3 and 5 were then created around zones 2 and 4. The pre requisite for the use of this method was that the HR at LT and OBLA for all players fell within zones. I found when I tested with a larger squad of players this pre-requisite could not always be met. The use of zones also still holds the limitation of giving the same weighting to exercise spanning the whole zone. For example if a zone which was 70-80% of HRmax had the same weighting, an athlete training at 71% would get the same weighting as someone training at 79%. It is difficult to ascertain however if this difference would affect physiological adaptation, and there appears to be no study to date that has examined this fundamental training question. However, with the method of Stagno, the zones are created around the thresholds, so there may well be a situation where players exercising in the same zone, gaining the same weighting, are working above and below a metabolic threshold. Impellizerri et al (2005) showed this could produce different results. It must be highlighted that although the zones are based on metabolic criteria, they are created with arbitrary values of lactate and are therefore not individualised as Lucia’s are. Another consideration overlooked by Stagno is the lactate response to intermittent exercise. The oxygen consumption during intermittent and continuous exercise at the same average intensity is similar at low intensities but significantly different at higher intensities (Bangsbo, 1994). Bangsbo also found higher blood lactate concentrations for intermittent exercise compared to continuous exercise at the same average workloads. We examined this and showed that this may alter the weightings in intermittent sports (Akubat et al, 2011). Another issue with using weighting individualised to a team is that it still does not account for individual differences. The graph below shows data I collected from a squad of professional players. Note how the regression from which the weightings are calculated is well below the data points for some players, possibly leading to an underestimation of training load. The iTRIMP section of this website examines what this could potentially mean for individuals.
In summary the work of Stagno highlighted some of the complexities involved in monitoring training load in team sports. They highlighted the need for specific weightings, although they failed to fully individualise these. Their use of zones was an attempt to move beyond the use of mean HR. The limitations highlighted exist, however they produced dose-response relationships and at the time this study was a big step in the right direction. However I could not help but think they had missed an opportunity. Having assessed the lactate profiles for the players in this study why not fully individualise and account for individual characteristics? Also was the use of zones necessary? Banister used mean heart citing calculating the TRIMP for each reading would be too problematic. However modern computing does not allow for that being an excuse anymore. Also with the previously mentioned limitations of zones why not assign each HR reading a weighting, thereby circumventing the need for zones. These questions led to the idea of the individualised training impulse.
AKUBAT, I. & ABT, G. 2011. Intermittent exercise alters the heart rate-blood lactate relationship used for calculating the training impulse (TRIMP) in team sport players. J Sci Med Sport, 14, 249-53.
BANGSBO, J. 1994. The physiology of soccer--with special reference to intense intermittent exercise. Acta Physiol Scand Suppl, 619, 1-155.
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.
IMPELLIZZERI, F. M., RAMPININI, E. & MARCORA, S. M. 2005. Physiological assessment of aerobic training in soccer. J Sports Sci, 23, 583-592.
STAGNO, K. M., THATCHER, R. & VAN SOMEREN, K. A. 2007. A modified TRIMP to quantify the in-season training load of team sport players. J Sports Sci, 25, 629-634