Can Random Signal and Noise (Stochastic Resonance) Improve Human Function and Athletic Performance?
>> November 26, 2016
For this unique topic, the best for me to start is by explaining how vibration can improve athletic performance.
I think that the Soviet coaches and scientists were the first to use vibration as a means to improve functional movements or even athletic performance. This could be traced back in the 1960s, when coaches in the Eastern Bloc started to use "contraction" type exercises such as oscillation training in their training ("secretly") to gain performance advantage in different situations (rehabilitation, normal training, conditioning).
Oscillation training involves a powerful muscular contraction, which enhances muscular strength and power. So this is basically sort of "vibrating the muscle" areas under tension (loaded) you wish to develop, or so.
Fast forward, in 1980s, Vladimir Nazarov assessed the feasibility of vibration to maintain strength and muscle mass among cosmonauts. The reason for this was when in space, reduced gravitational force might affect bone density, strength, and muscle mass. As a result, cosmonauts might have risks of bone fractures, muscle atrophy, and weakening of strength very quickly upon returning to earth.
It is not practical to have "gym" in space and what you might do is to use vibration for the said purposes. This way the duration of stay in space could be extended as well.
Effects of vibration on performance
Vibration has been used to elicit a stretch reflex in the muscles in order to "potentiate" the following performance. Of note, any preconditioning stimulus (such as using heavy resistance as well as vibration) could have the potential to improve subsequent task (performance). This is called "post-activation potentiation".
More recently, a training study provided evidence supporting the suitability of vibration training (Perez-Turpin et al., 2014). The authors noted that rapid performance gains in jump height were achieved and that these improvements obtained in shorter periods of time (i.e. 6 weeks).
According to the authors ... activation of muscle spindles from vibration could stimulate alpha motor neurons and promote stretch reflexes. They further clarified that long-term vibration training gained via neural adaptation was similar to effects of resistance training, that is the enhancement of motor unit firing, motor unit synchronization, synergist muscle contraction, antagonist muscle inhibition, and adaptation of the reflex response.
They postulated that strength increases following vibration training are of hormonal modulation (ie. changes), that is essential for muscle hypertrophy and force production.
Stochastic resonance vibration
I think that the Soviet coaches and scientists were the first to use vibration as a means to improve functional movements or even athletic performance. This could be traced back in the 1960s, when coaches in the Eastern Bloc started to use "contraction" type exercises such as oscillation training in their training ("secretly") to gain performance advantage in different situations (rehabilitation, normal training, conditioning).
Oscillation training involves a powerful muscular contraction, which enhances muscular strength and power. So this is basically sort of "vibrating the muscle" areas under tension (loaded) you wish to develop, or so.
Fast forward, in 1980s, Vladimir Nazarov assessed the feasibility of vibration to maintain strength and muscle mass among cosmonauts. The reason for this was when in space, reduced gravitational force might affect bone density, strength, and muscle mass. As a result, cosmonauts might have risks of bone fractures, muscle atrophy, and weakening of strength very quickly upon returning to earth.
It is not practical to have "gym" in space and what you might do is to use vibration for the said purposes. This way the duration of stay in space could be extended as well.
Effects of vibration on performance
Vibration has been used to elicit a stretch reflex in the muscles in order to "potentiate" the following performance. Of note, any preconditioning stimulus (such as using heavy resistance as well as vibration) could have the potential to improve subsequent task (performance). This is called "post-activation potentiation".
More recently, a training study provided evidence supporting the suitability of vibration training (Perez-Turpin et al., 2014). The authors noted that rapid performance gains in jump height were achieved and that these improvements obtained in shorter periods of time (i.e. 6 weeks).
According to the authors ... activation of muscle spindles from vibration could stimulate alpha motor neurons and promote stretch reflexes. They further clarified that long-term vibration training gained via neural adaptation was similar to effects of resistance training, that is the enhancement of motor unit firing, motor unit synchronization, synergist muscle contraction, antagonist muscle inhibition, and adaptation of the reflex response.
They postulated that strength increases following vibration training are of hormonal modulation (ie. changes), that is essential for muscle hypertrophy and force production.
Stochastic resonance vibration
Basically, there are two main types of vibration - sinusoidal and stochastic resonance vibration.
The sinusoidal has a constant vibration frequency that differentiates its "shape" from stochastic resonance, which has random vibration frequencies.
Most of (if not all?) the previous studies investigating vibration and performance (jump, power, speed, sprint, agility, strength, etc.) have used the sinusoidal type vibration.
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| This Figure shows the noise and signal of Stochastic Resonance |
A human can easily habituate (or adapted) with constant information or stimulus!
In contrast, stochastic resonance has vibration with randomized noise, which promotes unpredictable stimulus (i.e. random signal and noise), and increases sensory sensitivity.
Potential of stochastic resonance training to improve athletic performance
First, our body has a certain level (threshold) of detection capability and this is influenced by some factors (to be explained).
The signal of stochastic resonance may encourage the body to continuously be challenged or given by a "new stimulus", which adds up to the existing one. This can be progressively increased to reach an optimal level (i.e. good detection capability).
This "essential" noise increase the perception of information as a result of sensitization of the weak sensory signal (sub-threshold signal).
Of note, the weak sensory signal is increasing in aging people, those with a disease, illness, and injury - so you need stochastic resonance here to increase the detection capability (or to add to their "present" signal, that is weak due to injury - for example, as noted previously).
To date, stochastic resonance is mostly used in a rehabilitation setting, such as restoring normal functions of patients (stroke, Parkinson disease, etc.) and musculoskeletal pains - back, knee, neck, shoulder, arm, ankle, foot, and hip (see Elferig et al., 2011).
From the above, there seems a potential of using stochastic resonance in an athletic setting.
If the detection capability can be amplified by an added signal to improve human function; can that (stochastic resonance) be utilised to improve athletic performance? In addition, if vibration can be used to potentiate or improve athletic performance, a combination of vibration and random noise (i.e. stochastic resonance) for athletic performance enhancement seems promising.
Further research is necessary to understand its roles for performance enhancement (e.g. jumping, strength, and speed) and in which way it can be utilized to improve training quality.
