i presume it would be too easy if, say, 75% intensity would match with 75% MU.
In a trivial saying, Bench Press can be considered as Tempo which is 75% or less, so maybe we can go from there?
If true, 75% running intensity is 40% or MU and 100% running intensity is 100% of MU, we can see that each m/s of rincreased running intensity has a huge importance!!!
Then what about overspeed (>100% intensity) ?
This point has always been an interest to me. Besides neural pathways, what other positive effects occur when 1-5% assisted efforts are implemented? Would not assistance, such as tailwind, might have a much different MU recruitment pattern than resistance (such as sled pulls)?
Are resisted runs higher intensity than unresisted or lower?
Based on which criteria? MU recrutiment and freq (integral EMG), RPE, or GRF? Are resisted runs higher intensity than unresisted or lower?
Is 1RM bench press lower intensity than 60% 1RM press with max speed (acceleration)?
This is a problem of maximum… I think they are the same but they hit different parts of Hill’s curve Also what is the difference in MU involvement in very heavy resisted runs and light (<10%) resisted runs?
This is a complex issue… If you look at it generally, then both assume maximal MU recruttment (for now forget about strength deficit), but on my opinion light resisted runs have shorter GCT ad greter velocities, thus they develop speed-strength and explosive strength, and the other, high resisted run have greater GCT thus develop strength-speed and strength, or in other words different parts of the Hill’s curve (F-V relation).
Secondly, shorter GCT in light resistered runs my provoce greater myotatic reflex and thus greater recruitment…
Thirdly, there is a problem of coordination, or to be more precises skill and neuromuscular coordination, becasue of different pattern of neural firings and body mechanics (inclination etc), so both runs can have different impact on technique (skill). So, both can be considered MAX, but with different point on F-V (force velocity curve) and coordination (MU recruitment) impact…
MU involvement is only a reference to the number of motor units involved in an activity- not an intensity reference.
For Example, a bench press maximum lift is 100% intensity over 35 to 40% of Motor Units.
Tempo might be considered 60 to 75% intensity over 90 to 100% of MUs.
These are great questions without clear answers but it is the work over differing portions of the F/T curve that can create the conditions to get past a plateau, or, at least, to prevent a plateau in the first place.
can your Hi/Lo intensity principle be used in training the different parts of Hill’s curve (F-V relation)? Or in other words, doing just strength training and speed, and avoid middle part of the curve (which are going to rise, as you improve their endings - Hi, Lo)? To say, do the only very highly resistered runs, or very low resistered runs, and avoid middle resistered runs? How do you consider hills, as higly, middle or easy resistered runs??
BTW, dont forget that Hill’s curve is oversimplication, because it is used to explain muscle behavior in vitro and in lab with isokinetic loading… things are little different when it comes to real life (in vivo) multy-joint, multi-plane movements…
However you view the F/T curve, it is a means to define various activities. It can help in choosing activities for training and understanding their interaction with one another.
My Graph is more of a global view of how many MUs are used overall in the whole body by different activities, not how many MUs are called up within a single muscle group, which would be a reflection of intensity.
I intended it to be another tool for understanding the impact of various types of training.
Obviously, you can go further because the total MU involvement is the number of MUs within each muscle times the number of overall muscles, but I really intended this for comparisons between the high intensity activities outlined in the graph because that’s where the competition for physical resources really lies.
Quite an interesting thread going here…this place always manages to exercise my brain.
So are we to assume that a light resisted run of 20m will have less MU recruitment and be less CNS taxing than an unresisted run of 20m because of the decreased velocity and slighty greater GTC?
If that is the case, does that mean as the resistance becomes greater, and as velocities decrease/GCT increases, MU recruitment becomes less?
That’s why I said that Duxx’s questions were good.
I’d suspect that the very lightly resisted 20m accel would recruit slightly more MUs within each muscle group due to increased resistance outweighing the slight drop in velocity BUT more resistance would tilt the equation the other way, due to the resultant exponential drop in velocity.
At higher speeds, the drop in velocity from even light resistance would outweigh any increase in load/resistance.
Complicating things further, air resistance rises exponentially with speed, requiring more than 20% of all work to overcome at maximum velocity, relegating added resistance to a progressively lesser percentage with each increase BUT rendering an exponential drop in air resistance workload at max, due to a lower achievable top speed.
All too much for me to worry about! I just restricted the maximum resisted distance to 30m, which is the distance by which most acceleration is over anyway, and limited the resistance to a 10% decrement in timed performance vs unresisted time.
So, when thinking about the use of resisted runs in GPP work, should we be a little more cautious using light resisted accels due to the possibility of higher MU recruitment? Or, is the CNS involvment still not great enough to make us worry.
Whenever you are working on a high intensity componant, it’s high intensity. The other factors to consider are the total volume of high intensity work, which starts off low in GPP, and the technical side, which is easier to perfect when going a bit slower yet with complete extention, as with resisted work or hills.
Can we assume a novice sprinter will not be able to recruit as much of a percentage of MU:s as and advanced sprinter. And consequently, the rapid progress in a novice sprinter is mainly due to ’learning’ to use a greater percentage of MU:s? For elite sprinters, this is already history, so what remains is about utilising as much intensity within the MU:s used, thus having to also utilize strength training in order to be able to intensify work on the track in the first place (different portions of the F/V curve).
Is their an optimal order to continually improve recruitment of F/T fiber? What I mean by this is, sprint work (max speed) recruits what portion of an athlete’s available F/T fiber (or is it only the discharge rate) / compared to hang cleans? Their is always a trade-off between recruitment and discharge rate and I am trying to be clear as to the purpose of all the training elements?
One of the reasons for this question is, why would a conversion phase not be beneficial? I am trying to fully understand your reasoning?
If a squat recruits a certain percentage of F/T fiber? and a sprit a certain amount of F/T fiber, would not a jump squat be more appropriate (an improvement between recruitment and discharge)?
Or is it not a good idea to try to obtain these qualities at the same time?
Let’s turn your question around the other way:
“What is the optimal order of priority in training and what effect does it have on the F/T fibre?”
If you get the first part right, the second part falls into place.
Ok, I see your point, but would this point be also valid?
To continually improve speed, would not the qualities of the muscles/CNS also need to change? And how would those changes best be developed?
My analogy, If I had a race car, and the engine would only alllow me to travel at a certain speed, my velocity would not change until I improved the power of the engine. I could race that car over and over again, but nothing will change until I change the engine.