Training Stress Score explained. TSS

So far we have just been using Training Peaks as a diary of sessions. This is absolutely fine and this programme was set up to support people to exercise and stay healthy. However now we are starting to get a lot of questions around training to be fitter instead of purely exercising. The difference is outlined nicely in an article on the Mapdec App. If you are interested in the training aspect then please read on.  If not – STOP RIGHT NOW…. and continue to enjoy lots of varied exercise.

Training Peaks

Training Peaks is a training tool which can produce large amounts of data for analysis of your fitness progress, either by yourself, or you and your coach, if you are coached. It was designed by Andy Coogan and Joe Friel, a renowned coach with many books to his name. This includes one called ‘Fast after Fifty’ which is an excellent read for those of us in that age bracket. Like any model Training Peaks is only a tool which should be used flexibly to assist one, not as a rigid guide. Like every tool it has its weaknesses as well as its strengths.

Recording Progress

If you wish to use Training Peaks as a way of recording your progress you need to record every session you do on your calendar and allocate it a Training Stress Score. (TSS) See how below. Much of the data produced centres around this.  On the right hand side of each week in your calendar it lists your training stress score. You can look back over your weeks and keep a record of the score each week, this will help you decide when you should rest to allow your body to adapt. Your TSS should rise slowly over the weeks to allow your body to respond to training, ideally no more than ten percent a week. It then needs to dip, on average, every fourth week to allow the body to adapt. (Rest week)

Each week’s score ideally should be composed of a number of sessions, not just one or two massive efforts. If you exercise like that your TSS for the week will look reasonable but you are shocking your body rather than building fitness gradually.  This is one of the downsides of the model. If you make sudden jumps upwards you are risking becoming too tired and then you are susceptible to illness or injury, so it is a good guideline to make decisions around.

Tss jTP

Calculating TSS

People will probably either be going ‘Oh my God, not more’ – in which case ignore the rest of this. Or – wow, that looks interesting, tell me more. If you belong to this group then please read the rest of this, give it a try and ask us lots of questions on Beginners chat group.

Training Stress Score is calculated from the starting point of a TSS of 100 being generated by working as hard as you can for an hour e.g. a 25 mile time trial. This would be working at your RPE 8, your lactate threshold, or the top of your zone 3, bottom of 4 for those using a five or six zone heart rate model. Training Stress Score is a metric born within Training Peaks and has very little use in any other forum.

If you have no monitor you will have to guess for all sessions and providing you are consistent then it will more or less work.  To give you some guidance remember that 100 means you have worked as hard as possible for an hour.  A one hour RPE 5 bike ride is around 40 TSS, a one hour RPE 5 run is about 45 TSS. Running is harder than biking… Average walking for an hour is about 15 TSS. If an activity is more than an hour you multiply it up e.g. a two hour RPE bike ride is 80TSS, as one hour at this intensity is 40.  Similarly a three hour walk would be 45 TSS, as one hour is 15 TSS. If you do half an hour RPE 5 bike ride it would be 20TSS as a whole hour is 40 TSS.  Easy yoga perhaps TSS 10, strength training as above, maybe TSS 60 -70 if you are sore for a couple of days and 40 if it’s quite easy.

If you have a monitor of any kind which is linked to Training Peaks the monitor will upload your activity and its TSS providing you have entered your correct HR data.  It will not upload anything accurate for things like yoga or strength sessions. These will have to be entered manually, see above for guidance.

The programme also produces a nice little chart of your fitness progress which you can see if you are signed up to Premium.  Coaches can also see, whether you are on premium or free. For some people this will be of no interest at all, others may be fascinated and become obsessed by the progress of lines on their graph – beware! The graph looks something like this –


This is a graph for a month, the pink line is fatigue and the person has had a month of increasing fatigue, with some dips allowing a small amount of adaptation. This person also should perhaps take some recovery as the pink line is continuously climbing.  The blue line is their fitness which is building steadily. The yellow line is form which is decreasing as fatigue increases. Form is how well you can perform in a race or event compared to how fit you are. If this person rested to allow their body to recover the yellow line would come up and the pink one would go down. This would allow them to start building fitness again safely. It is also  what one would expect to happen in the few days before an event when you ‘taper’, or do less, so that you arrive at the event fresh and ready to succeed.

This shows a different graph showing spiking fatigue, (pink line) which is also constantly rising; this led to a dip in form (yellow line) and an increase in fitness (blue line) in the first half of the graph. This gain in fitness was then lost as the athlete became sick, and progress here can be seen in the second half of the graph, form has gone up with compulsory rest – Training Peaks doesn’t know you are sick so considers it rest time as no sessions are uploaded.  The downward slide in fitness is clearly evident, and the training fatigue drops drastically. The fatigue from illness is not recorded.

Corina TSS

Just to finish with here is a graph over a whole year showing spikes of fatigue coming from doing a number of events which the winter had been spent training for. Then there is a massive spike in fatigue in February, clearly visible, at which point the athlete became ill. Ho hum….

image0 (1)

Like all models Training Peaks should be used flexibly and, like all figures, these figures are open to discussion and varied interpretation but it is one way of measuring progress. Why not give it a try and ask questions and give feedback….


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