Brain Wave Entrainment is any procedure that causes one's brainwave frequencies to synchronize with a periodic stimulus (sound, vibration or light) having a frequency corresponding to the intended brain-state (for example, to induce a trance, dreams, sleep or relaxation.) It is also called the Flicker-response because of how staring at a campfire or the flickering of a burning candle can lull you into a state of calmness and serenity. There was an extensive article on this phenomenon by Gerard Oster in Scientific American in 1973. It may sound novel, but in many ways, this is old tech.
Stress: We all deal with it, yet we know how much better off we’d be — both physically and mentally — if we could only get it under control and find stress relievers that really work. While stress can be a positive, motivating factor at times (such as when you’re under pressure to perform well at work or to ace an important exam), more and more research shows that chronic stress impacts the body in ways similar to a poor diet, lack of sleep or sedentary lifestyle.
You are already far beyond the need for using an entrainment product as a meditation aid. Those who sincerely believe this to be the case would not have come searching for a meditation site such as Project Meditation to help them learn and practice meditation and brainwave entrainment. They would probably not even bother with using an entrainment aid; hence this entire discussion would be irrelevant to them. The fact that you are here, reading this, seeking to benefit from incorporating meditation and brainwave entrainment to aid in your existing meditation practice suggests you are not one of these folks whose development is so advanced that entrainment is of no use to you.
With digital upgrades, Berger’s machine is still in use today, known as an electroencephalography machine, or EEG. Berger used his machine to study the brains of psychologically normal and abnormal people and discovered the first brainwave, called the alpha wave and also known as the Berger wave, along with the faster beta wave, which he observed suppressing the alpha wave when subjects opened their closed eyes. 
I haven’t seen any research relating to using brainwave entrainment/isochronic tones and bodybuilding, so I’m afraid I don’t know how effective it would be to help with that. I have a few different tracks for increasing energy but I recommend this 1-hour track, which would fit better than my shorter tracks for a training session: https://www.mindamend.com/shop/energy-and-motivation/high-energy-builder/. The effects from these tracks are mainly felt while you listen to them, so I recommend listening to the energy tracks while you are training/lifting weights etc. I don’t currently have any tracks to help trigger the testosterone hormone.
Brainwave entrainment is a simple concept. It’s simply causing your brainwave frequency to align with some intended frequency in order to produce some intended result. It’s a way of modulating your brainwaves to resonate at a certain frequency. Being that there are certain dominant frequencies associated with different states of consciousness, this is being researched as a quick and effective way to induce states such as sleep, alertness, concentration, and even meditative and deep sleep states.
I was failing to achieve deep physical relaxation and looking for ways to shift my consciousness. After trying out many ‘solutions’ - including some truly bizarre ones - I decided to stop for a while and take a break before my next attempts at astral projection. That’s when I was recommended X. I must say it has been instrumental in helping me enter the state of relaxation and vibration necessary to a satisfactory OBE.
Wouldn’t it be a blessing if you could find a way to move through each day with a greater sense of peace and harmony, with heightened creativity and intuition, with a sharper intellect and a more positive outlook? For many people today, the deep, effortless meditation that brainwave entrainment provides is the key to a more fulfilling, peaceful and successful life.
Meditation Begins • Mind Chatter Slows Down • Great For Learning & Studying • Creative Ideas Flow • Reverse Brain’s Aging • Habits, Fears, Phobias Melt Away • Calm & Peaceful • First Layer Of Subconscious Mind • Gateway To Deeper Mental States • Advanced Focus • Relaxation Begins • Serotonin • Endorphins • Good For Anxiety, Depression, Stress, Panic • Mind Power • Happiness • Confidence
Binaural-beat perception originates in the inferior colliculus of the midbrain and the superior olivary complex of the brainstem, where auditory signals from each ear are integrated and precipitate electrical impulses along neural pathways through the reticular formation up the midbrain to the thalamus, auditory cortex, and other cortical regions.[6]
Generally speaking, the brain will usually entrain to the strongest stimulus which would be isochronic tones over binaural beats. So when you see people add binaural beats at a different frequency to the isochronic tones, that would not produce additional brainwave entrainment at another frequency. If they are both at the same frequency I haven’t seen any research to indicate whether that would be beneficial or not, but my belief is that it would weaken the potential for entrainment. When you look at the waveform of an isochronic tone there is a distinct empty space between each beat, making it very pronounced and effective. When you add binaural beats at the same frequency it looks like this: http://www.mindamend.com/wp-content/uploads/2017/11/isochronic-tones-binaural-beats-combined-waveform.jpg. The depth of the waveform is now half as deep and less effective. This is before the binaural beats are formed inside your head, where the waveform is hard to determine and measure. From listening to that type of combination the beats sound much less pronounced, which has to make them much less effective in terms of a brainwave entrainment stimulus, compared to isochronic tones on their own.
Why not? Because the flushing has nothing to do with the brainwaves or entrainment, and everything to do with the expectations we bring to the use of entrainment. We didn’t watch that sunset with any expectations of face flushing. We didn’t have any of those expectations while listening to that music. In short, there is a cause generating the effect, but the cause is our expectations, (excellent Article here) not the entrainment.
So to summarize their claim, they're saying that entrainment means that a binaural beat will cause your brain's electroencephalogram to match the pattern of the phantom beat. Well, if it did, entrainment certainly doesn't apply and would not be part of the equation, so we can scratch that off the list. But it doesn't make the claimed observation wrong. We do know that certain electroencephalogram waveforms are often associated with certain kinds of activity. For example, physical activity or REM sleep often produces an electroencephalogram with a sine wave of between 4 and 8 Hz, which we term a theta pattern. Waking relaxation with eyes closed often produces a pattern from 8 to 12 Hz, which is called an alpha pattern. There are only a few characterized patterns, and pretty general descriptions of what kinds of activities go with them. The claim made by the binaural beat sellers depends on much more granular and specific matches. For example, the claim that a binaural beat with a frequency of X produces the same effect in your brain as Vicodin is wholly implausible. Such claims presume that we know the exact frequency of the electroencephalogram in each of these desired conditions, and the fact is that brain waves don't work that way. It is wholly and absolutely implausible to say that desired brain condition X will occur if we get your EEG to read exactly X Hz.

A simple spinal twist can help you get a better night's sleep. It alleviates tension that's built up in your lower back throughout the day. Sitting on your bed with legs crossed, place your right hand down on the bed behind you and rest your left hand on your right knee. Sit up straight and inhale for four to eight counts, lengthening your spine as you breathe. On your exhale, begin to twist toward your right hand (don't strain your neck). Hold this position for four more full breaths, lengthening your spine on the inhales and deepening your twist on the exhales, if it feels comfortable. Repeat yoga asanas on opposite side. (These stress-reducing yoga poses also help calm anxiety.)

Listening to brainwave entrainment music will provide you with the benefits of a formal meditation practice. It will improve your mental clarity, your creativity and your ability to learn and to concentrate. It will bring you peace of mind and emotional stability. It is also one of the most powerful natural ways to cure insomnia and can dramatically improve the quality of your sleep.
^ Bittman, B. B., Snyder, C., Bruhn, K. T., Liebfreid, F., Stevens, C. K., Westengard, J., and Umbach, P. O., Recreational music-making: An integrative group intervention for reducing burnout and improving mood states in first year associate degree nursing students: Insights and economic impact" International Journal of Nursing Education Scholarship, Vol. 1, Article 12, 2004.
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