In internet forums, especially cycling forums, cyclists frequently refer to muscles getting "stronger" with training. A researcher frequently shows up and corrects them that muscle strength only has one meaning, maximum strength in a single contraction but he never gives an alternative way or term that might be used to describe muscle function and ability after a period of exercise. He simply criticizes any attempt for lay people to try to discuss this issue because they are not using the words properly. How are people supposed to discuss this?
It seems clear that muscle function after exercise depends on several variables. How long was the exercise period? How close to maximum was the muscle being used? What was the muscle contraction frequency (30/min is a lot different than 150/min)? Is there an acceptable term for this purpose? If not I would propose something like this be adopted and I would look for feedback.
My proposal would be Functional Strength% (%, min, rate). This is simply the muscle strength as a percentage of the maximal strength after being exercised as a certain percentage of that strength for a certain number of minutes at a certain repetitve rate. With this it would be clear to all that FS%(70,60,100)=70% is not the same result as FS%(50,30,60)=70%. I think we could assume the former muscle had greater aerobic capability.
Anyhow, I look forward to hearing others thoughts as to how to address this seeming deficiency in our ability to talk about how muscles behave in reality. If we could better measure this then it seems it would be possible to better predict what is best for an athlete in upcoming races. Is there a relationship between FS%(70,30,90) and FS%(70,60,90) that would better predict what that athlete should be doing for a 10 hour race (Ironman) or an 8 day race (RAAM)? Right now it seems like we are stuck with a one size fits all approach that suggests Ironman pace should be .8 of FIO2 or some such thing. Why can't we come up with an easy test that individualizes that advice based upon an "easily" measurable muscle test of fatigibility.
Thoughts?
Dear Frank, you raise some interesting points and also the issue that many scientists struggle with when they look at discussions between lay individuals. Let me first say that the interchange of terms like strength and force production will to many seem like the same thing. However, we have to be careful when distinguishing between maximum strenght/force and the conditions under which this varaible would be measured. Maximum force production for a muscle is elicited during a static contraction, although this force can go up during a contraction that lengthens the muscle but usually this is only achievable using a isokinetic dynamometer (e.g. kincom or cybex). During cycling the force production will be a product of pedal cadence (contraction velocity) which together produce power (force X velocity = power). Peak power is achieved at around 1/3 of maximum velocity (but this is not the maximum pedal cadence) and is usually found at around 120 rpm. However, you can only sustain peak power for 1-3 seconds before it starts to decline. So what you're really interested to know is what power output can I sustain for a prescribed period of time. This is invariably a balance between aerobic and anaerobic metabolic systems to provide energy without the detrimental effects of relying too much on anaerobic metabolism (for numerous reasons). I am confused by your term functional strength because it's not strength that you're interested in it's the power output required to cycle at a given speed. I am also confused by your term FIO2 and how this can be expressed as fraction e.g. .8.
There are some field based tests on muscle fatigue, which, as I have elluded to, would be based on power output and the duration that this can be sustained. You could then look at the power output to cycling speed relationship and then pace yourself on the basis of speed and probably use some physiological variable such as heart rate.
I am not an exercise scientists, but your question reminded me of a project we (three of us) undertook many years ago. I give a brief outline below, if interested.
We had already developed a complex mechanics recording system to record evoked and voluntary isometric contractions of human elbow flexors at a wide range of elbow angles. One subject undertook a regular daily isotonic elbow flexion (against maximal load) in one forelimb and we wanted to monitor the time course of change in performance (weight flexed), strength (Max vol force) at different elbow angles and any change in contraction speed (twitch, rate etc) in ~weekly expts. The exercise routine continued for ~6 weeks and experimental recordings for >20 weeks - as I recall.
During six weeks of exercise, after a latency, max (weight) performance increased 100% (doubled), MVF increased 20-25% but there were no changes in cont speed etc. It took ~20 weeks for return of MVF to normal. So there was a learning period - may be.
So, I think performance, strength (force), speed etc need to be cosidered with due care, compared against similar measurements under control conditions.
Hope some of this at least makes sense.
Dear Frank,
Your question is very important and not being aware of its importance, leads to much unnecessary controversy in the literature. This is why we suggested important variables to be measured in resistance training (see attachment).
With kind regards,
Urs Boutellier
- Badges
- Science topic
- Similar topics
- Mathematics
- Statistics