There are 3 Gunas that describe in Hindu philosophy the essential nature of energy, personality, foods, Ayurveda, and other elements of nature. These 3 Gunas permeate our understanding of yoga as well. I will associate the Gunas in terms of the energies that are presented in yoga classes in particular.
Tamasic Yoga – For me, tamasic reflects a lower energy. It is calm, thoughtful, less physical, and more balanced with mindful, peaceful thoughts. Some relate Tamas to things like sour foods, negative energy, and chaos. But I am opting for the former in describing a yoga practice. In essence, nearly all forms of yoga have a tamasic element. Seated meditation and savasana would probably best depict the far end of the spectrum. Restorative yoga, Yin yoga, and maybe even Bhakti forms of devotion could present a more tamasic energy.
Rajasic Yoga – Again, my definition, would associate rajasic energy with more physicality. In yoga practice, this action-oriented energy is present in Ashtanga, Power, Hot, and other intense forms of physical yoga. And the physical could relate to a required focus that is indomitable, exhibits perseverance, and resolves to find mental sharpness. Warrior poses and other strongly energetic arm balances and inversions would find the far end of the spectrum.
Sattva – I would maintain that most forms of yoga seek to find sattva. This is when the body is in balance both physically and mentally. It balances the center between rajasic and tamasic energies. It represents balance, peace, contentment, and centeredness.
I was talking with yogi friends before I taught class about something called Metal Yoga. I’ve seen this in several settings. There ARE people who live fairly calm lives, relatively speaking. They are probably not listening to EDM, Hip-Hop, or hard rock types of music. They are not doing CrossFit or Strongman competitions. They most likely don’t raise their voices or have violent tendencies. I’d say for the most part, they are Tamasic but have found their balance in that realm. Whereas, if you go to any school playground, 99% of the kids are going to be running, climbing, and screaming at the top of their lungs. There are adventure junkies who are slack-lining a tightrope a 100 feet off the ground, mountain biking steep switchbacks, and, yes, probably listening to the likes of Metallica and Korn. In this case, their peace if found in the calm spaces between the storms. They have energy that is excessive and needs to be expended to find peace.
There is a time and place for these types of energy. Those who seek to practice Ashtanga or Power Yoga enjoy detoxing through sweat and expending energy. While others are completely at peace with a gentler form of yoga. Based on personality, people will strive to whatever form that helps them find balance, or Sattva.
So to answer the question, why Metal Yoga, is it in line with Yogic philosophy, and is it appropriate? That is debatable. Yes, maybe some words and imagery are war-like and harsh. But if you read ancient yoga texts, like the Bhagavad Gita, it is written in the context of war. In the mythological setting with Shiva, Daksha, and Sati, Shiva creates a hero warrior, Virabhadra, to avenge the death of Sati. This is the origin of the poses of Warrior I, II, and III. So while we seek Ahimsa, non-harming and non-judgment and non-violence, Rajasic energies are still present. So these more forceful, intense energies ARE a part of yogic philosophy. As long as Metal Yoga participants don’t harm others or harm themselves, it is a way that they are working out their Rajasic energies. For me, it is a very appropriate way to rid themselves of the chaos in their minds and bodies. It is not necessary for everyone. But for a few who have more Rajasic tendencies, it is the perfect solution to finding Sattva, or peace.