Running and nervous system

I have a question regarding cardio. Do You know if maybe running is more demanding on the nervous system then for example conditionning circuit session from 4-6 exercise like described here MMA Related Performance Training - #2 by Christian_Thibaudeau ?
I’m asking because my strength workouts days which are after day of some short running session (5km) usually really sucks :frowning:

What I learned is that different types of training affect people differently.

For example, my wife and I both do various types of training sessions. She does Crossfit, spinning classes, and “normal” lifting workouts for hypertrophy. Oddly enough, the hypertrophy sessions drain her much more than the others and she crashes later in the day.

Crossift leaves her physically fatigued, but she doesn’t crash and maintains a high level of energy for the whole day. Spinning workouts are like nothing happened. But when she did some running, she would be the most trashed of all even though the running was less than 1/3 of the work of her spinning and at a much lower intensity.

Me, strength workouts have almost no impact on residual fatigue. I can do 2 or 3 strength sessions a day (I often did and do) and I don’t crash and I’m just as strong the next day. For example, I’m currently squatting every day (sometimes twice a day) always working up to a daily training 1RM (the heaviest single I can do with proper form and no psyching up). And the worst that will happen is that I’ll lift the same weight as I did the previous day. Even after squatting heavy twice a day, I’ll do at least the same weight the next day, sometimes more.

Hypertrophy sessions also don’t get to me. But lactic energy systems work ( destroys me. And it impacts my workouts for the next day, sometimes for 2 days.

And these are “beginner” lactic workouts. For example, two weeks ago I did 5 x 45 seconds all-out on the assault bike with 5 minutes of rest between bouts (I wanted full recovery to be able to give a maximal effort in all sets… I kept the number of calories burned per interval the same, 19). That’s not a lot of work and I was toasted for the whole day and did not have the motivation to train the next day.

If I do aerobic work (e.g. zone 2-3 cardio) it doesn’t affect my motivation or mental state the next day, but I’m flat in the gym. Like, my performance is worse but I don’t feel fatigued.

I’ve also trained high-level Crossfit athletes who could run 10-20k one day and hit a snatch PR the next day but who would get trashed by “bodybuilding work”.

Recovery is a lot more complex than some people make it out to be (sadly).

There are many systems that can be impacted by training.

  • Central nervous system
  • Peripheral nervous system
  • Psychological readiness
  • Metabolic factors
  • Mechanical/musculoskeletal system
  • Hormonal system

Inflammation, both local and systemic also plays a big role.

As well as neurotransmitters like glutamate, adrenergic sensitivity, etc.

Each type of training will affect each system differently and there will be individual differences in the resiliency of each system.

So, really, the only way of knowing how each type of training affects you is to try them out and evaluate them.

A few things I noticed:

  • The less you like something, the more it will make you feel fatigued and can even impact the next day’s workout (I suspect that it does so by “fatiguing” the zone of the brain responsible for resiliency). Also, hating doing something can affect central fatigue. That’s why my wife can’t run (she hates it) but can do the more demanding spinning (which she loves). To give you an idea of how much she hates running, when there is a WOD that includes running at her Crossfit gym, she does the assault bike instead!

  • The more adapted (and thus the better and more efficient you are) the less a type of training drains you. And since you have fewer adaptations to make following the session, you recover faster from it, even if on paper it is “harder”. That’s why my wife has a much harder time recovering from a hypertrophy workout (which she rarely does, only when she can’t go to a Crossfit WOD) and why any type of energy system work requires a lot of recovery time for me and strength work doesn’t require any.

  • The more you sweat, the more likely a workout is to impact the next day. This is purely observational and I suspect that it comes from reducing the level of electrolytes in the body (which you lose when you sweat). Electrolytes are KEY when it comes to producing forceful muscular contractions and can even impact your mental state. Me, when I do any type of energy systems work I sweat a lot and if I don’t take in electrolytes it will hit me hard the next day. If I don’t replenish electrolytes and rehydrate, I’ll wake up 3-4lbs lighter than usual and perform like crap. A pattern I noticed with a lot of athletes that I’ve trained (they must give me their bodyweight, state of well-being on a scale of 10 and workout performance on a scale of 10, every day).

  • The more muscular you are, the more “cardio” work will impact fatigue and next-day performance. This is because more muscle mass leads to more metabolite accumulations and more CO2 production during aerobic activity.

  • Being heavier (muscle or fat) also impacts recovery from cardio/aerobic training sessions because you have more weight to absorb with each step which will create more inflammation. And even inflammation that is not “felt” will impact performance.


Thanks a lot for the explanation. It is a huge amount of knowledge.
My personal first assumption was that I’m bad at running and that was the reason behind being without power in the gym the next day. Now I see that It can also be related to the fact that I don’t like running. I’m just doing it because I know it is the healthiest form of cardio. Maybe I will need to rethink my weekly schedule to leave the day off after running day.

A few thoughts on how to make endurance running more bearable.

Even for experienced athletes the rule of thumb has been that 40 mins running equals 60 mins of cycling. Due to the effect of having to support body weight, impact stresses etc. Its why you have to pedal so hard to get your heart rate high on a bike compared to running.

Run on softer surfaces, esp grass to limit impact strain.
Try to stick to zone 2 heart rates of something like 130bpm.
Initially limit continous runs to about 20 mins.
Try running in blocks of say 4 mins run followed by 1 min walk.
Run intervals, DONT make these lactic efforts. This is just to break the monotony of running slowly. Just something a bit quicker than a 20min plod. Aim for something like 2,000m total running. Run lengths of a sports pitch (100m) and walk the width of the pitch. You can mix this up with combinations of 100m and 200m runs. 10x100, 5x200 whatever …

If you are still getting worn out substitute 40mins zone 2 combining stationary bike steady state with inclined treadmill fast walk. This will get you into an easy running heart rate zone.

Yes take a day off after a running day.

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I’d like to run this idea about sprinting by you and other contributors or coaches (lousy pun intended).

Sprinting is one of the best modalities for fat loss and suits the muscle fibres of lifters much better than running. It is easy to limit the time of intense effort to a few minutes, so lifting gains are not cannibalized, yet it has a long EPOC and sprinters seem to be very lean (although maybe the sport selects for this phenotype).

I was a good sprinter and okay distance runner when young and lean. Now I am older and much more muscular, I am a good sprinter and a very slow distance runner. Never much liked distance running, which to me was always about conditioning.

For me, due to weather and pragmatism, most “sprints” are on a step machine at the gym (since unlike a treadmill you can easily change speed and accelerate). I like to sprint at a ten degree uphill angle to reduce the risk of injury. I do several moderate weight hamstring exercises prior to sprinting including some of the usual sprinting warmup stuff (A-steps etc.).

I had pretty good results last summer sprinting hard for 5-20 seconds, aiming to get the (admittedly inaccurate) MET display on the machine above 20 or 30 or 40 as a measure of consistency so I knew the sprint required about the same level of real effort, depending on the distance. I was aiming for effort levels of about 90%.

With real sprinters seeking to improve, you might only do five to ten sprints with plenty of time and stretching between them. It is about quality, to practice and repeatedly emphasize exactly proper technique, as well as avoiding injury. A 100m sprinter might do mainly 30-40m accelerations, perhaps 3-5 seconds of strong acceleration and actual effort. It is very easy to pull a hamstring going above 90% effort.

After a good warmup, I have been working up to doing 30-60 sprints going hard enough for 3-5 seconds that the (admittedly inaccurate) MET display exceeds 30 (or the inaccurate calories/hour exceeds 3000). I go slowly, moving but not caring about speed, during the other 55-57 seconds. So I am doing a lot of EMOM and, like CrossFit, one might easily overdo it and risk injury, though in this case virtually all the minute is rest, there is a lot of warmup, and I seem to find it far less arduous then say repeatedly doing high box jumps. But I get the similarities and also dislike these things about CrossFit (which is generally excellent in many other respects).

Any running coach would dislike this idea, saying quality could not be maintained and the risk of injury is too high. But if I rest and rehydrate briefly after every block of 5-10 sprints, I can maintain those (admittedly inaccurate) METs, so at least I am consistent. Following this, I have no hamstring pain nor any limitations the following day. I’m not a sprinter, and using a step machine is not like being on a flat track. I don’t want to pull my hamstring, but going at 10 degrees with long warmup and the sense to stop at the earliest sign, this has not yet been an issue. I mainly sprint for the fat loss and since doing them in this way does not really seem like work in the sense of lactate sprints or using the erg.

If you sprinted sixty times for five seconds, that is three minutes of very intense effort and acceleration. If you consider it sprinting, which you might reasonably not.

My question, putting aside injury risk, would multiple alactate sprints be effective for body comp, assuming heavy lifting and some lactate cardio was part of the mix? Or am I just risking injury and fooling myself? Or is machine running so different that the comparison becomes far fetched? Because so far it seems to provide a workout fun enough I will do it, with real potential benefit, and little residual soreness. And so far so good, (though I really do do a lot of hamstring work prior). Thoughts?

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This sounds like distance running, given you are taking over an hour to complete it, and not sprinting. It’s basically fartlek training. If you can do 60 sprints, you aren’t sprinting.

The time not spent running fast is basically very slow walking after a couple sprints; I’d be fine stopping instead but this seems to make it harder and would slightly reduce the calories used (which come mainly from the bursts) . It is true the overall time after warming up exceeds 30-60 minutes. I accept this may not be sprinting, but it sure feels like it and uses similar high levels of acceleration and power.

But the reason it may not be a sprint is not because you can do more than ten of them, and after each ten you definitely need to rest and rehydrate. Not sure whether characterizing this as intervals or fartleks makes much difference? I contend if you concentrate just on shorter times/distances you can do more. My question is, apart from some listed disadvantages, it is worthwhile.

In my training week, I also throw in some sprints, sled sprints and distance running. It helps me keep my body comp where I want it and it’s fun to me.

I think the thing that really matters in what you posted was this

If you enjoy it, you will put it the highest effort leading to the goal that you’re trying to accomplish.


Fair enough. My gut impression is most coaches would scoff. But if it works for me, it works. I don’t know if it will. But I’ll let you know.

Professional sprinters have the same lean phenotype and good ones probably very similar muscle fibre makeup. I’ve never been in that league.

But lifters vary a lot; likely a lot more than high level sprinters. Doing pretty heavy exercises (say 75-90% max), I can bang out a lot of them. Others couldn’t. So who’s to say what a maximum number should be, provided injury is avoided and there is consistency? It would be different if it was as technical as using blocks, or if technique was paramount.

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This seems to be working so far. I’ve read some people do fartleks by alternating fast and slow speeds with corresponding intensities of, say, 85% effort and 40% effort. My version is more 90% and 5%.

But in terms of burning calories, I can do far better on the climbing machine.