25 February 2010

Understanding how muscles adapt

Whenever I post on this blog about the nitty gritty of strength or endurance training regimens, many comments come back looking for a more detailed explanation. From my last post, in the comments we got into talking about training anaerobic endurance and effects of training generally on different muscle fibres.

This is where things get tricky because muscles and complex structures, and the adaptations they make to training are also fairly complex. Picking over the surface of some details and using this to make inferences about how to train is shaky ground. My general advice or those who want to understand training at a muscle physiology level rather than the simple prescriptive or principle based level that you’ll get from coaches and coaching books, is to read thoroughly through the anatomy and physiology of muscle. I’m not trying to be difficult here, but understanding training will always seem confusing with only partial knowledge of the physiological picture. Perhaps adding a good exercise physiology text to your pile of training books would be a good help and reference. Any of Ron Maughan’s books are excellent resources. His book Basic and applied sciences for sports medicine has a superbly clear chapter on muscle and it’s adaptations which by an old lecturer of mine Neil Spurway. Spurway’s writing on muscle, like his lectures, are a great pleasure to read!

But back to the nitty gritty. Reeve was commenting just then about anaerobic training, asking:

“What is the certain type of force which a muscle must be exposed to over months and years to develop (presumably) fast twitch fibres? And if I do anaerobic work, thus growing my intermediate fibres, what effect will I notice in my climbing? Will I feel stronger? Increase my muscle's capacity to handle lactic acid? Or just have bigger heavier guns?

Secondly, you state that recruitment will get poorer with endurance training. Is is possible to maintain it whilst endurance training (maybe by a few deadhangs at the start of each session, say)? I imagine (although this is purely specultation) that the body is capable of maintaining high levels of potential recruitment without having to use them all the time (I can deadhang then go to the fridge and hold an egg). Is there any truth to my speculation?”
High (near maximum) forces are needed to develop fast fibres. By high forces I mean hard boulder problems or hanging on a fingerboard with as much weight as you can hang on for less than 10 seconds or so. If you do anaerobic work, you’ll get better at that anaerobic work, and not much else. We come back to the specificity principle! Anaerobic work won’t make you stronger - the forces are too low. In fact recruitment is lowered to make the muscle more efficient at sustaining work over the length of sustained sport routes. Yes this work creates better tolerance of the chemical imbalances of hard anaerobic work in the muscle. Muscles won’t get dramatically larger.
As for maintenance of recruitment during anaerobic training - yes, some high force work mixed in is the thing to do to maintain it. One session a week bouldering while you are training a lot of endurance for a sport climbing trip would be a good example. A little fingerboard before your endurance sessions would have the same effect, but not as good.
Why not? Because ‘recruitment’ is not a simple attribute of a muscle that rises and falls. Lots of people think of it this way - simply the number of fibres the muscle can recruit for contraction. The reality is much more complicated. Recruitment composes of the number of fibres recruited, the frequency and firing pattern and timing of the firing, and the ability of the central nervous system to supply a strong enough stimulus. But we can understand it much more simply as the body ‘learning and remembering’ how to pull hard on holds. 
Endurance training in climbing is a constant reminder for the body teaching it to use the minimum of force. Hard bouldering is the exact opposite on the hardest moves. Using a fingerboard is great to stimulate the forearm muscles and remind the fast fibres to grow and be responsive. But it’s important to show the system some hard bouldering on a real climbing wall in order that the whole nervous system remembers how to pull hard.


Anonymous said...

So what will the intermediate fibres grown by short anaerobic work do? Or will they just be useless? (The book is £70 and my university library doesn't have it so sorry if this is answered in there..)

Dave MacLeod said...

intermediate fibres are best adapted for intermediate forces - like anaerobic work. So when you do a lot of anaerobic work over time, intermediate fibres respond most strongly and you get better anaerobic endurance.

Again this is a simplified view of the picture - all muscle fibres contribute to force production during the highest force contractions. But intermediate fibres have a balance of fairly large size (producing quite large forces) and abundance of anaerobic enzymes that can sustain contractions over much more time (like the length of a sport route) than fast fibres can sustain without rest. Another important point is that all fibres are plastic and take on different characteristics. So fast fibres can produce more anerobic enymes, more mitochondria and capillaries too if they are exposed to endurance training over a long time. But in the process may atrophy too if they are not exposed to high force contractionss over years.

You can look at the physiques of elite distance runners, sprinters and body builders to see the changes in muscle size based on long term training stimulus in action.

Ian Evans said...

The principles are simple: hard bouldering with adequate rest gets you strong; circuits with inadequate rest get you endurance. Train the one that fits your current goals.

I wonder whether folks who are getting this involved in the minutiae of muscle adaptation are doing so because they're plateau-iing ing with their strength training?

If so, they'd probably do better to train some other weakness--likely mental skills such as imagery, commitment, fear of falling, arousal management, etc.

Of course, understanding is valuable in its own right, but will learning the difference between IIa and IIb fibers _really_ help your performance? Might you not do better spending time on your mental game (or footwork, etc)? What's the % of failure due to mental weakness as compared to physical?

Jolli said...

Excellent topic.

One way to maintain better maximal strength levels while working on your anaerobic endurance is concentrating more on high force intervals instead of longer circuits.

Some examples all targeting anaerobic endurance:

A max strenght oriented anaerobic interval set:
- 10 times
- 15 secs work (~4 move boulders)
- 30 sec rests between boulders

This is written like this:
10 x 15"/ 30"

- Every boulder must be as hard as possible.
- Rest between sets: more than work time.

Then a different one targeting more on the basic anaerobic endurance for redpoints:
- 5 times
- 30 secs work (6-8 move boulders)
- 30 sec rests between boulders

This is written like this:
5 x 30"/ 30"

- Every boulder must be as hard as possible.
- Rest between sets: equal or more than work time.

And finally an endurance oriented anaerobic interval set:
- 4 times
- 45 secs work (~10 move boulders)
- 10 sec rests between boulders (chalking)

This is written like this:
4 x 45"/ 10"

- Every boulder must be as hard as possible.
- Rest between sets: equal or less than work time.

So: manipulating mainly
- work load
- rest periods
- work time
one can easily target the intervals for different needs.

People who lose strength easier than others should use more the strength based intervals and people who maintain power whatever they do but suck on anything longer than a minute of work should of course use the endurance intervals more.

Then again a bit different story is what to do if one wants to do mainly redpoints or is having an onsight trip coming. the training must be quite different.


Ryan & Henning said...

“What is the certain type of force which a muscle must be exposed to over months and years to develop (presumably) fast twitch fibres?” I am the second author of Spurway and Wackerhage ‘Genetics and Molecular Biology of Muscle Adaptation’ and our research is aimed at understanding the mechanisms that make muscles adapt to exercise.
Even speed and strength training turns fast fibres into intermediate and possibly even slow fibres. Thus there is no type of training that will increase the number of fast fibres. Fast fibres can only be increased by inactivity. Researchers in Scandinavia around Michael Kjaer have studied quadriplegics and shown that fast fibres increase in denervated muscles. This may come as a surprise but essentially the story is that more muscle activity will promote the shift to slower fibres and that less muscle activity will promote a shift to faster fibres.
So ‘why do sprinter train at all?’ is the prize question. Well the fibre type is one thing but fibre recruitment, sprinting technique, glycolytic enzymes all still respond to sprint training. The trick is to focus on high intensity training and to miss out on the aerobic training especially for the muscles that do the job.
Another issue important for climbing is neuromuscular recruitment training. Sure, maximal exercise is good for high recruitment but so is going for the pump. So how does it work? To lift a maximal weight, you will need to recruit as many muscle fibres as you can. But you can also train your recruitment if you go for the pump. OK, let’s assume you do laps until failure. Initially your neuromuscular recruitment is low as you have to produce forces that are below maximal with fresh muscle fibres. But over time muscle fibres lose their force due to fatigue and the only way to maintain force is to recruit additional fresh fibres until you recruit everything you are able to recruit. So saying that only maximal efforts lead to maximal recruitment is wrong. Sandee Jungbluth and Ralph Carpinelli have reviewed this well.
Finally a trivial thing which finally has been properly looked at. It is trainability: Studies by Monica Hubal on strength and muscle growth and by Claude Bouchards team on endurance show that people respond to different extents to an identical training programme. Some put on muscle or increase strength or their maximal oxygen uptake greatly while others do not respond at all to the same training programme lasting a few months. This is partially due to genetics – thank mom and dad if you are a responder – and partially to other factors. The take home message is that coaches need to get a feel for their athletes trainability as some will need much more input to achieve a given output than others. Only one thing is sure: Dave has, for climbing, an very high starting point and surely a very good trainability, while people like myself – to our great regret – have not.

Viagra online said...

One session a week bouldering while you are training a lot of endurance for a sport climbing trip would be a good example. A little fingerboard before your endurance sessions would have the same effect, but not as good.