I would like to know which fit is use to rebuilt FL relation in the paper « A comparison of two Hill-type skeletal muscle models on the construction of medial gastrocnemius length-tension curves in humans in vivo » Hoffman et al., 2012 (joint in PDF).
If i follow the model Torque (normalised by Maximal torque)=exp(-absolute[((L-L0)/L0)^b -1)/s]^a.
However, in the methods Maximal torque and L0 were obtain thanks to fitted lenght tension curves.
How the authors normalise torque by maximal torque and obtain muscle strain witout maximal torque and L0?
Thanks a lot
Hello Robin,
I do not have a direct answer to your interesting question on human med gastroc muscle. However, many years ago, we examined Force - Leng characteristics of human elbow flexors and by expt. It is attached if interested. Also, I remeber that Prof Wilkie studied F-V curve in human biceps (in JPhysiol).
Regards,
KW (Ranatunga)
Hi
I don’t completely understand your question thus I apologise if my response isn’t helpful. I have detailed our procedure for constructing the fascicle length-torque curves below. Effectively we establish the curve using raw data first and then use this to establish the normalised curves.
- Plotted raw fascicle length (mm) against active torque (N.m) for each individual subject.
- Individual curve (according to the equation provided) were fitted through the plotted individual data to return optimum length (Lo) and maximum torque (Tmax) variables. Variables within the equation were constricted using upper and lower bounds to ensure a physiologically appropriate fit.
- The group (mean) curve is constructed by using the mean Lo and mean Tmax variables from all subjects and using these in the curve equation. The group curve is constructed over the range of lengths observed across all subjects using the group variables.
- To get the curve using normalised torque and normalised fascicle length (as in Fig 2A of the second article), all individual data points are normalised to the Tmax and Lo for each individual subject and replotted. The same process as above is then re-run to establish a normalised group mean curve.
Best Regards,
Ben
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