Chakras meditators are quite different from martial art meditators, assuming that martial artists do meditate, or at least they do chi-kung, or at least some internal martial artists do chi-kung which they sometimes call nei gung, for want of a better name with a combat spirit or connotation. Notwithstanding, martial artists are different from chakras meditators in that the former put more (or most) emphasis on muscles.
In a previous post Chakras or muscles, I suggested Chakras meditators do some muscles chi-kung training. in this post, I shall suggest chi-kung meditator do some chakras meditation. Their meeting point is bone marrow meditation.
According to Zhou BiChen (趙壁塵), a Wu-Liu (伍柳) lineage Neidan (内丹) Taoist meditation master, author of the famous classic text Taoist Yoga (translated into English by Buddhist Charles Luk) said his practice was exactly Bone Marrow chi gung, the lost art that Zen patriarch Bodhidharma （菩提达摩） taught Shaolin monks when he first brought Zen Buddhism to China. The Zen master called his art Bone Marrow Wash (洗髓經) for bone meditation. Zhou might have a point.
Anyway, Taoist and Buddhist meditatiors need to generate huge amount of internal chi without resorting to muscles. A Nei Gung master on the other hand generates his chi primarily through activation of his muscles via the power of his breathing muscles, by way of powerful reverse abdominal breathing. You may wonder, how can one generate chi without exercising one's muscles?
A Nei Gung master is clever. He does not need to jog to activate his muscles to generate chi, he conserves or converts otherwise wasted energy of his powerful breathing muscles, and uses such energy to activate his muscles through carefully aligned fascia and other connecting tissues, muscles included. What does a Taoist or Buddhist meditator do?
A Taoist of Buddhist meditator uses the same breathing energy. But instead of acting on the muscles, he acts on the bones or, better put, the total bone structure, activation of which generate the necessary chi for his spiritual purpose.
Can a martial artist take advantage of a pure meditator's skill in bone marrow activation? Certainly yes. And the secret of all secrets is meditate on one's finger nails. I searched the literature, and I found out that there are indeed tai-chi masters who choose this route. They are practicing like the pure meditators, getting chi to the inner most of our bones.
What extra benefits? You figure it out by yourself!