Fiber recruitment until exhaustion

O.k. I want to know how muscle fibers are recruited when you have a moderate intensity muscle action performed until exhaustion. This is not relating to sprinting (high intensity) but rather to a maximum effort found in cycling that takes place over 30min to 1 hr.

My experience has been as you get near the end of the effort you are pushing as hard as possible on the pedals it just doesn’t make the bike go fast.

What is really happening? Assuming that there is adequate fuel and motivation what mechanisms are slowing me down? Since the effort is well below my vo2 max pace I am assuming I can get enough oxygen. But when I am done my legs are unable to put out any kind of effort.

normally muscle fibers are recruited in order of size or from slow to fast twitch. but there are instances in sport and training where this order is reveresed or rather the fast twitch only. during cycling s you described you would probably never recruit all of your fibers as your preceived fatigue would out scale your ability to recruit those fibers. as fatigue sets in your body will probably recruit more and more fibers to maintain the same work. but the extent of this recruitment is probably dependent on training and neurological factors.

I have included some weight workouts after hard endurance rides and though I am tired I still can lift close to what I would use when lifting before a workout. Doesn’t this mean fast twitch fibers are left somewhat untouched during the exhaution part?

your considering fatigue as only a biological effect not a neurological effect. pervious work can actually enhance latter work this is known as the after effect. this may not be the case though it could be simply your level of endurance, strength ect. it depend son a number of factors.

James,

Could you go into more detail about the after effect? Thanks.

You may be staring to run low on glycogen stores plus some dehydration effects.
I find 60 mins endurance running is a bit of a cut off point at which I start to tire. Prolonged endurance training and high carb diets tend to help this - staple of marathon training.

The high intensity wight lifting is not so dependant on the endurance/aerobic system.

My understanding is that “tonic” work can enhance other workouts. How would I find out what would be the effect of the tonic work so that I could enhance other workouts? I have read Science and practice of strength training and am refering to the two factor theory on training.

there is a nice section on the topic in supertraining i reccomend you and anyone for that matter pick up a copy. i believe its called “the after effect of muscular activity” if you dont have a copy and your hard up i guess i can type it up but its rather long, just let me kno.

I have the 5th edition. Would you know what section I should look under?

section 3.4.2 pg 163