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Athletic woman resting after a hard training in the mountains at
π Health and biotech

Workload: the subtle harmony between preparation and performance

Jacques Prioux
Jacques Prioux
Professor in Sports Science at ENS Rennes
Key takeaways
  • The concept of workload has made its appearance as part of the drive to optimise performance in sport.
  • The aim is to strike a balance between improving sporting performance and preserving the athlete’s physical integrity, by looking at the internal and external workload.
  • Numerous technological devices make it possible to accurately measure this external workload (the objective measurement of the work carried out by the athlete during exercise).
  • The data collected during training or competition is only useful if a link can be established between workload, performance, and potential injury.
  • However, each body reacts differently to the same protocol, so the difficulty remains in modelling this dose-response relationship and proposing tools to trainers.

In com­pe­ti­tions, all that seems to mat­ter is the end result: the per­for­mance in front of an audi­ence. But achiev­ing this result requires prepa­ra­tion. More and more research is being car­ried out to gain a bet­ter under­stand­ing of athlete’s bod­ies and the prepa­ra­tion process­es involved. Today, in the world of top-lev­el sport, every move­ment is scru­ti­nised and every vic­to­ry is the result of hard work and metic­u­lous preparation.

This has giv­en rise to the con­cept of work­load. “Over the last few years, there has been an expo­nen­tial increase in the num­ber of sci­en­tif­ic pub­li­ca­tions on this con­cept,” explains Jacques Pri­oux, uni­ver­si­ty pro­fes­sor at École Nor­male Supérieure in Rennes. This is where the real bat­tle lies, in the metic­u­lous man­age­ment of work­load; a del­i­cate bal­ance to be struck between improv­ing sport­ing per­for­mance and pre­serv­ing the athlete’s phys­i­cal integrity. 

“There are two types of work­loads: exter­nal and inter­nal,’ he explains. Over­all, the exter­nal work­load is most often quan­ti­fied using sen­sors (GPS, LPS, etc.). It cor­re­sponds to the objec­tive mea­sure­ment of the work done by the ath­lete dur­ing train­ing or com­pe­ti­tion. The inter­nal work­load cor­re­sponds to the body’s indi­vid­ual response to the demands imposed by the exter­nal load. It can, for exam­ple, be quan­ti­fied using dif­fer­ent phys­i­o­log­i­cal and/or bio­log­i­cal para­me­ters.” To ensure that the ath­lete is in the best pos­si­ble phys­i­cal con­di­tion, it is impor­tant to study the rela­tion­ship between the exter­nal work­load and the work­load spe­cif­ic to the ath­lete, the inter­nal workload.


To observe and under­stand exter­nal work­load, researchers need to analyse the ath­letes’ activ­i­ty dur­ing train­ing and com­pe­ti­tion. “Tech­nol­o­gy plays a very impor­tant role,” admits the pro­fes­sor. It is through tech­nol­o­gy, and all the tools it offers us, that we can car­ry out mon­i­tor­ing.” Var­i­ous sen­sors, such as the GPS (glob­al posi­tion­ing sys­tem) for out­door sports (foot­ball, rug­by, etc.) and the LPS (local posi­tion­ing sys­tem) for indoor sports (hand­ball, vol­ley­ball, etc.), enable extreme­ly pre­cise analy­sis of the ath­letes’ activ­i­ty. How far have they run? At what speed? How many accel­er­a­tions? Decel­er­a­tions? And so on. “The clos­er we get to the top lev­el, the more cru­cial this infor­ma­tion becomes,” he insists. “I am cur­rent­ly super­vis­ing a the­sis in which we’re work­ing on data from play­ers from Brest-Bre­tagne Hand­ball, i.e. the high­est lev­el in women’s hand­ball in Europe. They are all equipped with iner­tial units (anoth­er avail­able sen­sor) dur­ing training.”

In this way, it is pos­si­ble to pre­cise­ly analyse the work car­ried out by an ath­lete dur­ing train­ing. This makes for much more opti­mal pro­gram­ming. “It would be just as valu­able to obtain the same data in com­pe­ti­tion con­di­tions,” admits Jacques Pri­oux. “How­ev­er, the cost of equip­ping sta­di­ums, gym­na­si­ums and play­ers with these tech­nolo­gies is very high.” This data, although impor­tant, remains worth­less unless it is con­sid­ered in rela­tion to the impact of this Work­load on the ath­lete in ques­tion. “Work­load is only of inter­est if we study its rela­tion­ship with per­for­mance, but also with poten­tial injuries,” he insists.

Personalised training

It’s a well-estab­lished fact that every sin­gle body is dif­fer­ent. The same work­load may not feel the same to every­one. And each body will require dif­fer­ent prepa­ra­tion to opti­mise per­for­mance while lim­it­ing injuries. That’s why analysing inter­nal work­load is so impor­tant, and there are many tools avail­able to researchers to enable this to be quan­ti­fied. “At the end of a group hand­ball train­ing ses­sion, for exam­ple, we ask the play­ers to assess the lev­el of dif­fi­cul­ty of the ses­sion on a scale of 1 to 10,” explains the pro­fes­sor. “If one play­er marks the ses­sion at 5, while anoth­er marks it at 10, we already have an impor­tant point of com­par­i­son: the state of fit­ness of the two play­ers is prob­a­bly not the same.”

In this exam­ple, for an exter­nal work­load con­sid­ered to be sim­i­lar, the feel­ing dif­fers between the two play­ers. This data can then be cou­pled with oth­er phys­i­o­log­i­cal data, such as oxy­gen con­sump­tion, heart rate or lac­tic acid con­cen­tra­tion, to objec­tivise the effort made dur­ing training. 

Relationship between dose and response

In this con­text, the dose cor­re­sponds to the work­load and the response cor­re­sponds to per­for­mance or injury. The­o­ret­i­cal­ly, if the work­load pro­posed is too low, the athlete’s lev­el of fit­ness will prob­a­bly be low­er than that obtained with a high­er work­load. How­ev­er, too high a work­load can have neg­a­tive effects on the athlete’s body, in terms of fatigue for exam­ple. The dif­fi­cul­ty there­fore lies in iden­ti­fy­ing and then using the right work­load. “If the work­load pro­posed dur­ing train­ing is too high, the fatigue lev­el incurred will also be high,” explains Jacques Pri­oux. “The risk is that you won’t improve your ini­tial lev­el of per­for­mance and you’ll end up with an injury. If the work­load pro­posed dur­ing train­ing has been cor­rect­ly adapt­ed, the fatigue lev­el will allow opti­mal recov­ery, favour­ing an improve­ment in your ini­tial lev­el of per­for­mance and reduc­ing the risk of injury.” 

This dose-response rela­tion­ship is the sub­ject of a great deal of sci­en­tif­ic research, par­tic­u­lar­ly using arti­fi­cial intel­li­gence. The aim of this sci­en­tif­ic work is to mod­el this dose-response rela­tion­ship and pro­vide coach­es with tools to help them plan and indi­vid­u­alise the train­ing they offer their ath­letes. “There is still a great deal of progress to be made in this area, but the goal looks increas­ing­ly achiev­able,” con­cludes the professor.

Pablo Andres

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