Hello! I’ve been “using” intervals.icu for several months but just now trying to understand more about how it works. Lately I’ve been wondering about the load calculations after certain workouts. Yesterday I did a Threshold Interval Workout (10 x 3min @ 6:15), where I’ve set my threshold pace as 6:15 under settings. I walked 60sec between each set, and did a mile w/u and w/d for a total of about 7.5mi and a gap of 7:15min/mile. The load for yesterday’s workout was 70.
Today I plan to run about 7:49 pace for an hour…and when I input that into the calendar, the estimated load is 64. I am using Pace based load calculations.
I’ve looked at other runs from the past and it seems like the intervals.icu just uses overall moving time and average GAP for the run. Workout days like yesterday, though, definitely put more stress on my body, even if my total pace including my warm up, cool down, and the walking in between slows down the average pace. Are there settings I’m missing that would better account for the training load from workouts? It seems like the easy run is overrepresented as far as load goes (or the workout is underrepresented).
Many watches report power too, you could switch to power load instead of pace load. If you already have such a device, you just need to reconfigure the power load to take priority over pace load (“Training load priority” in your settings - per workout type).
The reason is that the load from Pace isn’t processed in the same way as with the Power. For Load from Power, the algorithm uses NP (Normalized Power) which drastically increases load for higher efforts because it is a result of the 4th power value.
This doesn’t work for pace, AFAIK, and consequently isn’t used. Like said in the former post, use Power if you have it. Else HR may be better for interval runs. Pace should be pretty good for steady runs.
Yes, Normalized Power would be great for running. I don’t have a power pod and don’t trust it based on what I’ve read.
I decided to “cheat” a bit and instead of walking or jogging between reps I started to do a standing rest to see what would happen. Since the system looks at moving time only, my overall pace for an interval day vs regular day is a lot faster now, which has contributed to a bigger load rating for the interval/workout days (now a delta of 25 load, which seems more reasonable).
This is interesting. Just looking at my pace loads versus my power loads (I run with a power meter, which I’ve found to be fairly consistent) I’m not seeing a significant difference in the differential between workouts and slow runs.
Here are some samples with values based on my recent runs:
Run Type | Duration | Distance | Pace Load | Power Load | HR load
Easy | 45 min | 8.5 km | 41 | 43 | 23
8 x 1k | 55 min | 12.2 km | 71 | 73 | 52
Easy “long” | 75 min | 14.2 km | 69 | 71 | 35
So both pace and power estimates load of a 75 min long run to be more or less equal to a workout with 30 minutes at around threshold plus some warm up and cool down.
It’s one of the reasons I decided to use HR load instead. I feel like the relative sizes of the load values are more representative of my perceived effort. No clue what the best representation of my actual training load is, though.
I think the 1k distance will not be influenced all that much. It’s something like 3m30s to 4 min intervals which (almost) reach a steady state?
Very short intervals like 30s or less, will result in higher differences Power/Pace.
From those numbers, I would indeed think that your HR zones are not well aligned with Power and Pace.
Which one of these are you using for HR load?
For comparison, power load for this session was 76. My 75 minute easy long on Sunday got a power load of 71, whereas the HR load was 38. So where it’s almost a 1:1 ratio for workout:easy long going by power, the HR ratio is 1.45:1.
I realise that the culprit for the differential is a mismatch in the calibration of the zones. As I did a 5k time trial on Saturday to get a decent FTP estimate, I can be fairly confident in the current FTP. I’ve also got about a decade of running and racing with a HR strap, so I’m fairly confident about the threshold HR estimate.
The more interesting point of discussion here is what’s the correct load relationship? Is a 75 min easy run where I average 65 % of HR Max as taxing as a 30 minutes sub threshold + WU and cool down, as claimed by power estimated load? Or is the load for the latter 45 % higher than the former, as claimed by HRSS load?
I’ve never tracked training load in any meaningful way as a runner, beyond weekly mileage, so I would love to understand more about what’s what here.
That’s another can of worms
The TSS load originated in the cycling community and is widely used. But the same questions/remarks are coming up because the same flaws are observed. The feeling of fatigue for long slow compared to short hard is not correctly balanced in the TSS system. But until we have something better, there’s not a lot of choice…
Thanks! I’m sure it’s a can of worms, indeed. But is there a “general consensus” that one ratio is more correct than another?
I’ve chosen HR load simply because the ratio is more in line with my perceived effort differential. A 75 min easy run feels like a breeze compared to a 30 minute threshold workout + WU and CD. But if the goal is to have CTL track fitness as closely as possible, it seems one has to be more correct than the other.
Please excuse my ignorance if there are no clear answers to these questions, and I’m just talking nonsense here
Unfortunately not. It’s actually a heavily biased outcome where some predicate one and others are doing the exact opposite.
I would advice to test for yourself and see what works best for you. If the numbers and you feeling diverge, try the other side.
When it comes to very hard and short intervals, it’s easier. The Fitness chart is essentially a view on your ‘aerobic’ performance. Whatever the short hard sessions result in, that’s more a peripheral muscle adaptation then a cardiovascular one.
Chiming in again that it appears taking away the walk or jog rest between reps by doing a standing break has helped the calculated moving pace faster vs doing the walk/jog rest. I’ve been following the same route to do my threshold intervals so the total distance covered is the same regardless. Since the avg pace is now faster for the same distance covered, the load calculation is higher.
I never looked up how normalized power on a cycling workout is calculated. But if there was a “normalized pace” for running where the system automatically or by some manual setting can exclude parts of a run that isn’t contributing to “work”, we could get a better overall reading. For example, ignore paces +4min/mi slower than threshold pace, or something like that, where the user can set the “ignore” pace.
Hi,
But, removing the resting parts wouldn’t be very representative, right ? If you let it calculate without the rest, then it gives you the same load you would get if you ran say 5x1600m (8.0km) without rest so, of course the load would be higher, but that’s not the case in reality… Isn’t it kinda “cheating” the system ?
