With the rapid advancement in technology over the last decade, we have access to literally dozens of different metrics from both our watches and the software we use to analyse runs. For athletes and new coaches this can be overwhelming and it can be hard to know where to start in terms of analysing data.
In this video we will go over the most common and useful metrics for during a run , post-run analysis and general training metrics ( which look at overall training load and trends ).
Common metrics to view when running include
Cadence
Heart rate
Power
Speed/Pace
Grade Adjusted Pace
Effort Pace
Metrics used in post run analysis include
Leg Spring Stiffness
Duty Factor
Stride Length
Vertical Oscillation
Ground Contact Time
Running Effectiveness
Metrics used to analyse Overall Training include
Duration
Vert
Distance
Acute Training Load
Chronic Training Load
Training Stress Balance
FTP/CP/ Threshold
Training Intensity Distribution
Before we discuss these in depth it’s important to keep in mind a metric is only useful if it gives us information we can act upon to help improve our training. If there is no take home or action one can derive from the metric then there is not much point analysing it ( other than pure interest).
What I mean by that is, for example, Stryd has the ability to analyse a runner’s foot path – ie the movement of their foot through space. For road runners, this can be valuable to highlight areas of inefficiency. For trail runners however , where the terrain makes every step slightly different, we can’t make any meaningful conclusions from the foot path. Might be fun to look at, but analysing it will not lead to any recommendations for the runner.
Metrics are only valuable if they can help guide us or our runner to more effective training. In. this video we will keep to those metrics that can help us make a positive change in training.
Metrics to analyse during and after training runs
We have discussed Power , pace, speed , effort pace and grade adjusted pace in the Intensity videos so I wont go into any of these – refer back to that video for more info.
Cadence and stride length,
– I will discuss ideal cadence in the running technique video but in this video, I want to talk about what to look for in cadence data in post-run analysis.
I have lumped stride length in with cadence as they are strongly linked, and analysis of one is limited without considering the other.
One quick point before we go any further – you will often see cadence numbers of 170-190ish but may also see numbers lower than 100 mentioned. 180ish refers to how many times left and right leg hit the ground per minute , 90 refers to how many times left or right leg hits the ground per minute , so 90 and 180 are the same. Some watches report single leg some double leg.
The main thing we are looking for is changes in cadence. When we fatigue, cadence can decreases or increase; it depends on the athlete’s individual biomechanics and if they are slowing down, staying constant or speeding up.
Let’s look at the relationship between the two and how it changes.
First of all it’s important to understand speed is a product of cadence x stride length. If we want to keep running at the same speed and one of those metrics drops the other will have to lift to compensate.
For example if one is running at a cadence of 90 and stride length of 1.4 metres and they start to fatigue their cadence might drop to 88 but if they increase stride length to 1.43 metres speed will be the same or their stride length might drop to 1.37metres but if their cadence increases to 92 then speed will remain the same.
Fatigue can affect athletes in a number of ways, but lets consider two scenarios
1) Speed is slowing down
2) Speed is staying constant
( and this is most useful in the context of flatter runs – speed, tempo or even long flat runs)
Speed slowing down
When our pace slows down, a few things can be happening to cadence / stride length.
1) Stride length is the same , cadence decreases
Action to take : Cue the athlete to maintain cadence when they become fatigued
2) Stride length decreases , cadence stays the same
Action to take : Cue the athlete to either increase cadence to compensate for the reduced stride length or increase stride length. The latter is usually far more difficult than the former.
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3) Stride length decreases , cadence increases
In this case the athlete is already trying to offset the reduced stride length by increasing cadence and if they still can’t maintain speed, its likely fatigue levels are simply too high.
Action to take : Revise pacing targets
4) Stride length increase , cadence decrease
Whilst this is uncommon and usually and cant be maintained for long it does happen.
Action to take : cue increase cadence
Keep in mind all of these reactions to fatigue are subconscious. The athlete is not deliberately choosing to reduce stride length or cadence , it’s their body dealing with fatigue as best it can.
Making the athlete aware of what happens when they fatigue means they know what to focus on to prevent the pace from slowing down.
Speed staying constant
In our second scenario of speed staying constant but cadence changing it just means the fatigue levels are not yet to a point where speed suffers.
Changes in cadence and stride length have been effective in pushing back fatigue and allowing the athlete to continue at the same pace.
However when you see a change in cadence or stride length and no increase in speed it indicates that fatigue is present.
This is one way you might determine if an athlete is coping with a session or not. If for example you gave them a session of 4 x 8 minutes and was unsure of how they were handling the session you can check cadence and stride length data to see if any signs of excess fatigue.
Sometimes it’s obvious, eg if the pace drops off at the end, or in the last rep, they speed up significantly, we know they are struggling or feeling good. But often the pace is consistent, and the athlete’s feedback on perceived effort is not any different to the previous week. By analysing cadence and stride length data, we might see that last week their cadence went up and stride length went down, whereas this week it stayed very consistent. This is a sign they were dealing with less fatigue as they didn’t have to make any changes to run biomechanics to get through the session.
The other consideration with cadence is it can vary with speed for some athletes and be very consistent regardless of speed for other athletes.. Neither is right or wrong , it is just a reflection of the athletes unique biomechanics.
So if an athlete has a cadence of 80 when running slow and 90 when running fast they shouldn’t be trying to increase cadence when running slower . I will talk in more detail on this in the running biomechanics video.
Another use for cadence in post run analysis is to assess when the athlete is hiking vs running.
For most athletes a cadence of \< 140 ( 70) indicates hiking , with the exception of hiking fast on the flat or gradual hill where some athletes cadence can go higher than 70.
A software platform like WKO5 can measure how much distance was covered hiking vs running in training and races using cadence. This allows us to gain valuable insight into the athlete’s fitness ( how much hiking vs running uphill did they do ) and race execution ( did they run too much of the early hills in the race or did they hike too much of flatter terrain later in the race). It also helps plan long runs progressions and how much vert they should have – the video on Vert discusses long runs and the balance between hiking and running.
Key Take Homes
Cadence is a valuable metric and whilst there is no one number is best, monitoring it during our runs allows us to note any changes and can then focus on it to maintain good form.
It is a very useful metric for a coach to detect any biomechanical changes that occur when the athlete fatigues, and also the amount of hiking vs running in each run.