Over the last 5-10 years the use of software to help manage training load and fatigue levels has become more prevalent. There are many advantages to this, one of which is being able to determine what the impact of a specific sessions training load will have on overall fitness and fatigue levels. This can be especially useful when managing a taper for an event.
Generally speaking you should be aiming for a positive stress balance for the day of your target event, but the exact number (or extent of the positive stress balance) will depend on the type of event you are preparing for as well as how high your training load was in the preparation period. Research has shown that the best results for track events (typically sprint, time trial or high intensity events) comes with a positive stress balance of approx +30, while peak performance for endurance events is more likely to occur with a stress balance between +10 and +20. The stress balance you should strive for will depend a bit on personal experience but may also be impacted by the event, for example when tapering for a multi day tour it may be more desirable to start with a higher balance (above +20) and then let the first day's racing start to bring it down. This way you can help delay the onset of fatigue unlet a lot later in to the tour.
So, if you know what stress balance you want to achieve for an event, how do you go about making sure your taper works effectively and that you can hit those magic numbers on race day. Well it takes a bit of foreknowledge and sometimes a bit of mathematics.
First and foremost you need to recognise that a key purpose of your taper is to shed fatigue but retain speed. A positive stress balance indicates zero fatigue as well as 'freshness', which should be viewed as how ready you are to perform (this can be overdone so don't simply aim for the highest possible number).
The first thing to understand is how the training stress balance is calculated and how you can manipulate it.
Quite simply the training stress balance (TSB or SB for short) is the difference between your short term stress and long term stress (STS and LTS for Golden Cheetah users) or Acute and Chronic Training Loads (ATL and CTL for WKO+ users). Long term stress is your indicator of fitness while Short Term Stress is your current training load. If your current training load (STS/ATL) is higher than your fitness level (LTS/CTL) then you will most likely be feeling fatigued.
For example, if your STS is 150 and your LTS is 120 then your Stress Balance (SB) will be:
120 - 150 = minus 30.
Conversely if you have dropped off your training then your STS might be lower than your LTS and you will have minimal fatigue as you are riding within your capabilities and not stressing your body. Over a short period of time this leads to peak performances, however over longer periods is leads to reductions in fitness and performance. That's where tapering comes in. It's a short term or reasonably sudden reduction in training load to drop your STS/ATL to below your LTS/CTL.
To continue our example, the rider with a LTS of 120 starts to taper and after a few days their STS reduces to 125, they would have a SB of -5, so almost fresh. A few days later it might reduce to 110, at which point their LTS might also reduce to 118. At this point their SB would be:
118 - 110 = plus 8
How to control the stress balance and rate of taper
The key to being able to manipulate the STS/ATL is knowing what the training load will be for any given workout and then comparing that value to the current LTS. During a taper you will still need to keep training at a high intensity, but you can reduce the overall session load by keeping the duration down. By managing the balance of session intensity and duration we can then structure a taper that includes regular, but short bouts of high intensity exercise while also facilitating overall recovery and a reduction in the fatigue levels prior to the race day.
To calculate the approx training load for a session you need to break it down into the different efforts and durations. Don’t worry about being overly pedantic about the accuracy of this as you can manage the exact taper on a day to day basis as required. The training load for an individual session is calculated using an Intensity Factor (IF), which is the percentage of your threshold that the session or interval was completed at.
Approx IF values for various sessions or races are as follows:
- Less than 0.75 recovery rides
- 0.75-0.85 endurance training rides
- 0.85-0.95 tempo rides, aerobic and anaerobic interval workouts (work and rest periods combined), longer (>2.5 h) road races
- 0.95-1.05 lactate threshold intervals (work period only), shorter (<2.5 h) road races, criteriums, circuit races, longer (e.g., 40 km) TTs
- 1.05-1.15 shorter (e.g., 15 km) TTs, track points race
- Greater than 1.15 prologue TT, track pursuit, track miss-and-out
The IF is then used in a formula to calculate the training load for a session. This formula is:
Training Load = (Intensity Factor ^ 2) * 100 * Hours
This then brings about two ways we can estimate the training load for an entire session: we can select the IF value that reflects the overall session intensity weighing up both the hard and easy components, or we can add them up as separate components. To demonstrate this more clearly lets walk through an example of a rider who is about to start their taper for an event that is 10 days away (being a Sunday)
Current Short Term Stress (STS): 150
Current Long Term Stress (LTS): 125
Current Stress Balance (SB): minus 25
The first day of the taper is a Friday. The session today will still include a range of intervals, lets assume that the session will be 2hours long and include 3 x 10 minute threshold efforts, 3 x 2min Vo2 efforts and 8 sprints of 10-20 seconds each. All remaining time will be ridden well down in to the recovery zone. The approx training load for this session would be:
Training Load = (Intensity Factor ^ 2) * 100 * Hours
Threshold intervals = (1^2) x 100 x .5hrs = 50 TSS
Vo2 intervals = (1.15^2) x 100 x (6/60)hrs = 13.2 TSS
Sprints = (1.5^2) x 100 x (2/60)hrs = 7.5 TSS
Recovery riding = (.6^2) x 100 x (82/60)hrs = 43.7 TSS
Total Training Load for the session = 50 + 13.2 + 7.5 + 43.7 = 114.4
So, despite this session containing a sizable interval component, it’s training load is 10.6 points below the current LTS/CTL score and therefore the stress balance will get closer to zero. This then leads to the second component of the taper, which is the ongoing and exponential reduction in training load as the taper continues. In our example we can see that a 2 hour training session containing little more than 38 minutes of intervals and 82 minutes of recovery riding provides a training load quite similar to the current fitness levels. Therefore to facilitate a sufficient drop in the fatigue levels/stress balance the key variable we need to manipulate the duration of the session. So lets have a look at the Saturday. For today we are going to keep some interval work in but it will decrease as will the ride time. The session will only be 1.5hrs in duration and it will include 2 x 8min threshold efforts, 2 x 2.5min Vo2 efforts and 6 sprints.
Threshold intervals = (1^2) x 100 x (16/60)hrs = 26.6 TSS
Vo2 intervals = (1.15^2) x 100 x (5/60)hrs = 11 TSS
Sprints = (1.5^2) x 100 x (1.5/60)hrs = 5.6 TSS
Recovery riding = (.6^2) x 100 x (67.5/60)hrs = 40.5 TSS
Total Training Load for the session = 26.6 + 11 + 5.6 + 40.5 = 83.7
So you can see that a few small changes to this session have dropped the training load even further, down another 30.7 points. The remainder of the taper will continue in this fashion and the exact content of each session can be carefully planned to ensure that the training stress balance hits the right numbers on race day.
By using this methodology you should be able to manipulate the rate at which your stress balance changes and therefore make it easier to achieve a specific stress balance for your target event. However, this leads to two fundamental questions:
- What do I do if my stress balance isn't dropping fast enough?
- What do I do if my stress balance is dropping too fast?
Well, if it's not dropping fast enough then you need to reduce the level of training even more than you already have. This may mean you opt for a very short but sharp session, such as a 10minute warm up, 10min TT effort then 5-10minute cool down. This would be 30min total for an IF ~.85 and a training load of 36 - which is going to have a significant downward impact on your stress balance while also maintaining the speed focus. You might also opt for a complete rest day (zero training load) or a short, active recovery session (20min = 12 TSS). Both of these values are considerably lower than the LTS/CTL they would lead to a quicker recovery (and this just highlights the importance of rest days in out training programs).
On the other hand, if your stress balance is coming down too fast then it means you will need to increase the training load for one or more sessions (depending on proximity to your target event). This is best done by adding intensity rather than duration and preferably so that you still have at least one easy recovery day before your event. There are a variety of workouts that can be added at this point however the key is to match the workout to your race. The more 'race like' the workout the better.
Finally, it is important to remember that the numbers are just that, numbers. Don't get sucked in to obsessing over a specific number. Simply aim to keep up some speed work through your taper and feel fresh on race day. Too much rest or too little intensity in this final week can leave you feeling a bit flat so don't be afraid to do a hard workout, just use your common sense and perceived exertion levels to dictate what is required.
Best of luck!