Is there a simple practical example where knowing hemodynamics values or
respiratory frequency/volume would make a difference in reading SmO2/ThB
Yes look at the Nick Mclean example in the other thread.
Is there a case where having EMG values is beneficial or preferable over
Yes we know that SmO2 recovery trends under specific situations are very close to CrP recovery. But if we create a " flat" SmO2 in an all out load and tHb is flat or increasing further than we need SEMG.
Crp. in this cases we see whether we have a change in SEMG due to an intermuscular change and still a maintaining of activity in the tested muscle .
In some cases we see SmO2 showing a " nice " recovery " but Cr.P and SEMG not.
Even thb than has different options in the recovery depending on limiter. Below the abstract of an old study we repeated with different tools.
Resynthesis, while Muscle pH and EMG Amplitude Remain Depressed
Alberto Mendez-Villanueva,1,2,* Johann Edge,2 Rob Suriano,2 Peter Hamer,2,3 and David Bishop2,4
Conrad P. Earnest, Editor
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This article has been cited by other articles in PMC.
The physiological equivalents of power output maintenance and recovery during repeated-sprint exercise (RSE) remain to be fully elucidated. In an attempt to improve our understanding of the determinants of RSE performance we therefore aimed to determine its recovery following exhaustive exercise (which affected intramuscular and neural factors) concomitantly with those of intramuscular concentrations of adenosine triphosphate [ATP], phosphocreatine [PCr] and pH values and electromyography (EMG) activity (a proxy for net motor unit activity) changes. Eight young men performed 10, 6-s all-out sprints on a cycle ergometer, interspersed with 30 s of recovery, followed, after 6 min of passive recovery, by five 6-s sprints, again interspersed by 30 s of passive recovery. Biopsies of the vastus lateralis were obtained at rest, immediately after the first 10 sprints and after 6 min of recovery. EMG activity of the vastus lateralis was obtained from surface electrodes throughout exercise. Total work (TW), [ATP], [PCr], pH and EMG amplitude decreased significantly throughout the first ten sprints (P<0.05). After 6 min of recovery, TW during sprint 11 recovered to 86.3±7.7% of sprint 1. ATP and PCr were resynthesized to 92.6±6.0% and 85.3±10.3% of the resting value, respectively, but muscle pH and EMG amplitude remained depressed. PCr resynthesis was correlated with TW done in sprint 11 (r = 0.79, P<0.05) and TW done during sprints 11 to 15 (r = 0.67, P<0.05). There was a ∼2-fold greater decrease in the TW/EMG ratio in the last five sprints (sprint 11 to 15) than in the first five sprints (sprint 1 to 5) resulting in a disproportionate decrease in mechanical power (i.e., TW) in relation to EMG. Thus, we conclude that the inability to produce power output during repeated sprints is mostly mediated by intramuscular fatigue signals probably related with the control of PCr metabolism.
Depending how complex you like to go the answer is no: SEMG is great for SEMG and NIRS is great for NIRS , that's what they are designed for.
If you go more mainstream than YES NIRS where you have tHb reactions can give you a lot of SEMG trend information when you combine it with the needed physiological reactions discussion. Remember both are very local feedbacks. With NIRS on a nonpriority muscles we can get more feedbacks, but with a SEMG on a nonpriority muscle we get no real feedback due to what it can measure .