Question about Muscle types and training

no matter what race you run, your slow twitch fibers are always recruited first

The myth is that faster movement requires fast motor units. This is not necessarily true. Slow-twitch motor units are directly responsible for low activation intensity requirements regardless of speed of movement. It is the strength demand the determines the use of fast units or not. For example, you can run along at 200 strides per minute (which is fairly quick) yet use only slow-twitch motor units. You may be running just 9 minutes per mile at 200 strides per minute. However, if you increase the intensity to 5:00 per mile, you might use far more fast-twitch motor units, even if the stride rate is lower.

Think of recruitment as a ramp. As momentary load requirement is increase, so is the involvement of more motor units and faster motor units.

Hey, there were a few other posts in this thread that got deleted. What happened to them? They weren't offensive or anything...

Anyway, thanks to those who replied.

Note the following: when Lance gets up outta the saddle, drops a coupla gears and starts hitting high revs going up those Pyrennees mountains, he is accessing his ST fibres more than (say) Ulrich who sits in his saddle and grinds uphill in the big gears.

So, although Lance's legs are turning over faster than Urich's, he is using his ST fibres more. So don't automatically / knee-jerk link faster turnover with faster fibres. The effort/load of each rev of Lance's is lower than that of Ulrich (in his big gears) so he can easily take care of this with ST fibres, and even 100rpm is no big deal for such fibres. Lance generates more overall power (he goes up the hill faster), but turning over his revs faster, thereby generating more watts.

Now, we know that Lance has a stunning endurance ability, not generating much lacate even at a high percentage of his oxygen uptake. So, if you wanna be a well-trained endurance-based athlete (like El G, for example), that's what to aim for: to be able to run very quick while accessing primarily ST fibres and not having to recruit FT fibres and generate a ton of lactate by so doing.

Since you mention the 800m, an 800m runner would do a lot of aerobic training early in the training year (and an 800m race is 60-66% aerobic, depending on source) to delay the build-up of lactate until as late as possible in the race. This was indeed the basis of Lydiard's training of Peter Snell, who would regularly run 20-milers for endurance.

Learn more about the requirements of your event so that you can have more confidence in the type of training you are doing.

So is the key to make your slow twitch do more work by making them stronger. The way I understand what you said is that the fast twitch are engaged to stride out longer. Stride lentgth is a strength based function. Since the fast twitch hypertrophy more they are stronger and hence are utilized more when ramping up the pace. From everything I've read, the fast twitch fatigue quicker than the slow twitch so you are at a disadvantage to engage them early in a distance race. If you make your slow twitch muscle fibers stronger then they can carry the load at faster paces and you don't have to engage the fast twitch until the end of the run when you start picking up the effort or sprinting? Is this right?

How do you strengthen the slow twitch fibers so that a person can carry on the faster pace without tiring as quick?It would seem that you'd have to run right at the threshold pace all of the time.

Also, I wonder what makes a fiber "slow-twitch". I'm assuming that it responds less quickly to a input from the nervous system than a "fast-twitch" fiber. There would be an inherant limit in how fast a slow fiber would turnover so to speak. Wouldn't it be better to teach the fast twitch fiber to carry on for longer periods of time than to teach a slow twitch fiber to work faster *and* stronger?

Hey "MoreQuestions,"

I didn't think I would be answering other people's questions in this thread that I started since I consider myself still learning the ropes. But, I'll take a stab here: As to the first part of your post, from what I've been recently reading the issue isn't really much about training for raw "strength" for the slow twitch fibers. As Tinman said the more power/strength required the more the fast twitch muscles get called into action. The real issue for training the slow twitch muscles is training for long enough to stimulate growth of mitochondria/capillaries so it takes longer for them to fatigue. As for your second question, why think in terms of either/or? I think long training helps both slow and fast twitch fibers gain endurance. I was just reading about how long training helps the fast twitch b fibers take on some characteristics of slow twitch fibers. The fast twitch a fibers have a very hard time gaining endurance no matter what you do.

I am learning so much these days. Unfortunately, that means I am starting to question my coach who last spring said that slow running is useless for me to get good at 800m.

I believe, and I could be wrong, that slow twitch muscles can be trained to actually work faster. I believe that was what Lance basically did in his training- got his slow twitch muscles used to working at the higher cadence, and did so to the point where his ST fibers increased to comprise 20% more of his overall muscle than when he began training.

interesting thread