Thanks its just something that has been bugging me. What difference in power development does using the correct frequency have? In improving your sprint
Thanks for your time, last question regarding my new globus unit. You have stated the reactivity programme was for jumpers! Why is that? What is different about this program. I have it on my unit. Thanks again
Reactivity is at the upper limit of frequencies available. It’s just a name, but we tried to differentiate it a little from the other explosive force settings. The belief is that if, for instance you need to keep jumping as for basketball rebounds, you need to be able to react very fast.
I may not be 100% correct, but since in a sprint you need to develop high force for a certain amount of time, in that case you need to develop the highest power. Maximum power is developed by muscles not at their maximum speed but somewhere between 1/2 maximum speed and 1/3 of maximum speed.
I’m not a specialist, so you need to verify this information with a competent coach like Charlie and others in this forum, because there may be other factors.
Do these reactivity and explosive pre set programes any good for developing a sprinter
I hope Charlie or somebody else can answer that question. Charlie’s recommended stimulation protocol is 10/50/10, i.e. 10 seconds on, 50 seconds off, repeated 10 times. The Compex and Globus programs are approximately 5/25/20. Globus may add a few program geared toward Charlie’s recommendation, depending on demand, since it already offers the custom programming ability. The machine you have, being a more economical European model will not add lengthened programs.
In a separate thread a member had asked about how many more repeats to do to make up for the shorter on time. The reply from Charlie, if I recall was about 16 repeats.
Yeah would like charlies opinion too. Thanks for replying too. Though the machine I have I can programme to do whatever I need by using the pause button, I programmed constant stimulation for a min at 120 frequency lol not used yet
I have always used 6 to10 sec cont/50 sec rest /10 reps per body part.
Those who favor 6 sec tend to be throwers, linemen, high jumpers in my experience.
You can tell by the drop off in contraction intensity towards the end of the rep. If it drops off much at all, I’d go to 6 sec. At 5 sec, I would imagine you could use a shorter break but maybe not as short as 25 sec if you plan on more than 10 reps.
The duration of exposure will determine the role EMS will play in the overall training scheme, so I keep the EMS blocks short to stay in the explosive area.
Better to repeat cycles at intervals rather than have one long EMS training block IMO.
The compex and globus machines recruit the muscle indirectly through the stimulation of nerve endings.
ELECTROSTIMULATION-INDUCED CONTRACTION
Electrostimulation-Induced Contraction
Voluntary skeletal muscle contractions result from impulses commanded by the Central Nervous System (CNS) and transmitted through the nerves as electrical signals and eventually recruiting the desired muscles. The same can be achieved starting from an external electric impulse replacing the voluntary signal.
Tissue Sensitive to Induced Electrical Stimuli
Electrical impulses activating nerves are similar to electrical impulses activating muscles. Therefore one can decide whether to stimulate nerves and indirectly stimulate the muscles, or directly stimulate the muscles. However, there are differences between the two.
Direct Stimulation through Muscle Fibers
Direct stimulation of the muscle fibers bypasses all the rest of the CNS. However, this choice, even though possible, activates the muscles as if in a lab setting, by themselves and a bit out of of context, which is less conducive to training.
Difference between Rest and Threshold Potentials in Muscle
The other important factor is that the difference between rest potential and threshold of muscle fibers, i.e. the difference between -90 mV, and -55 mV, is 35 mV. In other words the electrostimulator will have to overcome this difference to stimulate muscle fibers.
Difference between Rest and Threshold Potentials in Nervous Fiber
The membrane potential of nervous fibers at rest is -70 mV, and the threshold to trigger an action potential is -55 mV. Therefore to excite nervous fibers it is necessary to change the potential of the membrane by only 15 mV. Comparing this value to the 35 mV calculated for muscle fibers, the difference is huge: one will need 57% less potential to stimulate nervous fibers.
Applying Electrostimulation on Nervous Motor Units Fibers
The diameter of motor nervous fibers is larger than other nervous fibers’. They are also characterized by an insulating liner that allows for faster transmission of action potentials, insulation from outside impulses and a very precise selection of which fibers are going to fire. This insulation effect tends to insulate nervous fibers even from the stimulus of an electrostimulator. Fortunately there is a gap just before the nervous fiber reaches the muscle, and from here it is possible to send an external electrical impulse to the muscle. In addition the neuromuscular plate is situated on the muscle surface, closer to the outer skin. Therefore the electrical signals to stimulate the muscle do not need to be to strong, and it is possible to limit side effects.
Source: (EMS DIGEST) http://docs.google.com/Doc?id=dgw665wn_33f8wb6ff9
CURRENTS
To obtain the desired contraction effect of electrostimulation, the current level will have to reach a compromise between a high enough current level to generate a strong contraction, and limited enough to exclude undesirable effects.
The current will have to be high enough. The excitation of the muscular tissue will be maximum when the electric current suddenly changes from zero to a certain value, and also when it suddenly changes from that value to zero.
Muscle fibers also have adaption capability, which means that they will tend to adapt to a certain current level. This means that if the current increase is too gradual muscle tissue will adapt to it, and the current will not elicit any contraction. Therefore the change of current will have to be sudden.
The type of current that reflects the characteristics just listed is a rectangular waveform, for which the current increase is practically instantaneous, which also has the following advantages:
Limited polarization effect
Limited nervous fiber adaptation
Good recruiting of nervous fibers
Low current level
Excitation Mechanism and Necessary Impulse
To excite the nervous tissue the following conditions are necessary
Enough current through the targeted tissue
Adequate duration of the stimulus for the muscle group
The next figure shows the relationship between current intensity and duration, which also changes for different muscle groups.
Chronaxie and Rheobase
The relationship between current intensity and duration has been determined by Lapique. As duration increases, the current intensity necessary to trigger a contraction decreases.
Another characteristic of body tissue is that of accomodation, which means that any tissue gets used to a particular stimulus and consequently needs next time a stronger stimulus to trigger a reaction. Lapique defined two parameters as reference points to characterize and compare the effects of electrical stimuli: rheobase and chronaxie.
Rheobase is defined as the minimum current intensity necessary to trigger an excitation (action potential), no matter how long the duration of the stimulus is.
Chronaxie is defined as the duration necessary to trigger a reaction, when current intensity is twice the rheobase. This value is an excellent compromise to trigger a good contraction in a reasonably short time, without generating any accommodation, and without causing any of the negative side effects.
Chronaxie in Various Muscular Groups
Chronaxie is an important parameter for electrostimulation, because it determines the duration of each impulse. Therefore the duration of each impulse has to change depending on the muscular group. Generally there are 6 different areas to stimulate, with 6 different chronaxie values and therefore 6 different impulse durations. Average values are the following.
Lower Leg, 430 microseconds;
Upper Leg, 380 microseconds;
Lower Torso, 330 microseconds;
Upper Torso, 280 microseconds;
Arm, 200 microseconds;
Forearm, 230 microseconds.
Source: (EMS DIGEST) http://docs.google.com/Doc?id=dgw665wn_33f8wb6ff9
It’s important for those who need to deeply understand the mechanisms of EMS, i.e. coaches who need to customize a training program to target specific goals, to highlight a very important and misunderstood feature of EMS: recruitment order.
Voluntary muscle activation activates muscle fibers in a very specific order, from smallest Slow-Twitch (ST) fibers, to largest Fast-Twitch (FT) fibers. Early research seemed to point out that this was reversed in EMS exercise: FT fibers were activated more easily than ST fibers. However, very recent research has demonstrates that EMS does not reverse the natural recruitment order, and it rather activates fibers indiscriminately, and onlywhich based on position relative to the electrode pads.
Voluntary recruitment order, as quoted from Zatsiorsky’s & Kraemer’s - Science and Practice of Strength Training; Human Kinetics, Champaign, IL:
The orderly recruitment of MUs (Motor Units) is controlled by the size of motorneurons (Hennemann’s size principle): Small motorneurons are recruited first, and requirements for higher forces are met by the activation of the large motoneurones that innerfate fast MUs.
Early studies that experimented on single fibers in a lab setting, found that FT larger fibers were easier to excite: see Gorman and Mortimer, The effect of stimulus parameters on the recruitment characteristics of direct nerve stimulation. However, those studies were performed on anesthetized animals, attaching electrodes directly to muscle fibers by cutting through the skin. Since this were the only available findings at the time, the literature on EMS started using this as a self fulfilling benchmark, which gained acceptance.
SOURE: (EMS DIGEST) http://docs.google.com/Doc?id=dgw665wn_33f8wb6ff9
martn76,
That is not correct. All electrostimulators using pads, Compex, Globus and other electrostimulators, including those that utilize Russian protocols, all recruit muscles indirectly through the muscle nerve plate.
As a matter of fact, Globus has a clinical portable version (Genesy sold to Athletic Trainers and Physiotherapists), which has both square waveforms and Russian protocols in it. When I connect this unit to my leg, and switch from rectangular waveform to Russian waveform, there is no difference whatsoever, except for the weakening of the contraction with Russian. If you read the EMS Digest appendix on Russian currents it is explained why a Russian contraction is weaker (implicitly shorter pulsewidth).
You even quoted the passage from the EMS Digest that implies that direct stimulation cannot happen with pads.
to excite nervous fibers it is necessary to change the potential of the membrane by only 15 mV. Comparing this value to the 35 mV calculated for muscle fibers, the difference is huge: one will need 57% more.
This means that if you need to dial your unit to 100 to trigger the nerves, you will need to dial it to 157 to trigger the muscle directly. But by the time your muscle is triggered directly, it was already contracting from the nerve-initiated signal.
Direct muscle stimulation (when needed) is normally done In Vivo. I.e. the researcher or the doctor touches the muscle fiber with a microscopic probe (normally they have to slice through the skin of the animal to do this). It may be done on patients who have been denervated from a stroke or an injury, for particular diagnosis of the health of the nerve-muscle connection.
Read the whole article from top to end…
The article is by Globus.
Modern EMS systems recruit muscle differently because they rely on action potentials, and threshold potentials that differ for each type of tissue.
MEMBRANE POTENTIAL
Membrane Potential at Rest
Organic tissue is characterized by electrical charge in it. The cell membrane, known as sarcoplasmatic membrane, has electrochemical mechanisms that manage to keep negative charges inside, and positive charges outside. The accumulation of opposite charges on the two sides of the membrane creates an electrical field across it which, as any electrical field, is characterized by an electric potential. Each living cell is characterized by this potential, which is known as membrane potential. Its value at rest is different from the value during excitation.
Purpose of the Membrane Potential
Membrane potential acts as a filter. If the stimulation is small it cannot penetrate it and nothing happens. If the stimulation is large enough, it can overcome the membrane potential, penetrate inside the cell and activate it. Therefore it filters out signals that are not strong enough.
Threshold Level
The value of the electric potential, which determines whether signals are strong enough or not to be further transmitted is the threshold value. Both muscular tissue and motorneurons have a threshold potential of -55 mV (milli-Volt). However, their rest values are different: -70 mV for nervous tissue and - 90 mV for muscular tissue. This is the reason why it’s easier to stimulate muscles through their respective nerves.
Action Potential
When a stimulus decreases the membrane potential below its threshold value the cell membrane inverts its polarity. That is, as soon as the membrane potential is lowered from -55 mV to a value closer to zero, the membrane triggers an automatic ion-exchange mechanism across itself, which switches the membrane potential from negative to positive. This polarity inversion is called Action Potential.
Purpose of the Action Potential
Action Potential acts as the messenger of a nervous signal. The polarity inversion switches the membrane of the next cell below its threshold level; this in turn causes another action potential in the next cell, and so on as in a chain reaction.
Sequence of Action Potential Generation
At rest the membrane potential is -70 mV.
External perturbation, i.e. stimulus, changes the membrane potential to -55 mV.
Beyond the threshold value the ion exchange mechanism triggers polarity inversion, i.e. the action potential, which is transmitted along the nervous fiber.
The action potential excites the membrane of the next cell, propagating the action potential mechanism to the target fiber.
What Happens if the Threshold is not Reached
If the initial stimulus does not reach the threshold value, there is no transmission of action potential, and the stimulus causes only a local effects.
Direct muscle stimulation refers to a current that bypasses the CNS and stimulates the muscle fibers…directly nothing to do with probes or plates directly on the muscle. The action potential needed to do this is usually greater hence you need a greater current and frequency. The threshold needed to stimulate muscle indirectly through nerves is much lower so you need a lower current and frequency. This has nothing to do with in vivo. Yes the Globus programmable has the Kots protocol available but the modern EMS protocols on the Globus and Compex work differently. Modern EMS systems can achieve the same effects as the Kots protocol but they rely on using Lapiques Law to achieve this. Its like the ball and chain principle. The threshold for stimulating nerve cells is on 70mv whilst the threshold for direct muscle stimulation is 90mv. Yet if you stimulate the nerve cells, the current is propagated down the nerve cells to the muscle, hence you can recruit the muscle indirectly. Please read the article carefully…
Yes, i think 20 might be a few too many at 5/25, although another option is to go 10 in one session and another 10 later in the day separated by at least 4 hrs. This might be desireable in the case of an injury that limited other means of training- like a calf injury etc.
Can a frequency of 90Hz+ be used during Capillarisation and recovery modes to target the type IIx fibres?
Type IIx muscle fibers do not benefit from capillarization, and capillarization is by definition a low frequency stimulation.
What I’m saying above is explained in the book Application of Muscle-Nerve Stimulation in Health and Disease, Springer 2008, Vrbova, Hudlicka, Schaefer Centofanti. Muscle fibers IIx, by definition, do not utilize aerobic mechanisms to convert energy into muscle contraction. Capillarization instead increase the amount of capillary in a particular muscle fiber, thereby increasing the amount of oxygen that can be supplied to that muscle fiber. But if you want to utilize that fiber for anaerobic activities, you wouldn’t be able to take advantage of the increased blood supply. Therefore you would not benefit from increased capillarization.
Low-frequency stimulation is instead prevalently used for endurance training; research on animals and humans has shown that low frequency stimulation has the capability of increasing capillarization in muscle fibers, no matter what the fiber type was at the beginning (of course it takes several weeks to achieve this).
I hope this answer your question.
I hear what you’re saying… But capillarisation of the type IIx fibres does have benefits in terms of nutrient delivery and muscle warming effecting nerve signals, as long as there is no shift from white to red. This seems to be why CF style tempo seems to have so many benefits. It is aerobic work at an intensity that still requires FT fibre involvement… bringing about capillarisation.
Maybe it’s only a question of semantics. Capillarization implies a shift white to red: by definition of capillarization, you have more capillaries, or more tortuous paths for the same capillary, thereby reaching more cells.
If CF-style tempo has benefits, then it could be because of the increased nutrient delivery as you are explaining. But increased-nutrient delivery can be achieved just with a program like Active Recovery (which by the way sweeps frequencies between 2 and 8 Hz).
General blood flow increases around all tissue increasing heat available, which can lower elecrtrical resistance.
Increases in heat can also be generated by increasing density, which might possibly help explain why the fastest individuals often find it so easy to warm-up and why they can maintain it for so long when they’re really ready to fly (they aren’t so far off the critical threshold temp to start with ??)
This may be a lot to ask, but where is the evidence that this actually occurs with your tempo training, and that it brings these specific benefits? I’ve had trouble verifying it on my own.
I seem to remember Charlie citing research that seemed to show that capillarisation and the increased warming of the motor units allowed faster nerve transmission?? I to would like to see a reference so I can prove all the aerobic haters wrong… (including my coach :eek:)!
I have come across an article that discusses among other properties, shortening speed and temperature: Human skeletal muscle fibres: molecular and functional diversity; Bottinelli, Reggiani; Progress in Biophysics and Molecular Biology, 2000.
You can buy it on-line (I got a copy from my local University). It’s above my level, so I’m not able to really explain it. But it does say, I quote: “Vo of human fibres shows a very striking dependence on temperature.” Vo is defined as Unloaded shortening velocity. I’m not sure if this applies to this discussion, but I may reread the section and try to report it in here if you are interested.