I made a post about the types of yoga in a previous post, but I will re-iterate, there are two types of yoga in India, the most popular is Prayama Yog and the other is Waryam Yog. The first is what is used by Sadhus (holy men) and more recently Ayurvedic promoters, who believe that using yoga and breathing techniques they can heal various ailments and diseases (i.e high blood pressure, diabetics, cholesterol). The Sadhus use Prayama Yog to settle the mind and focus it towards meditation.
The other form is Waryam Yog, which is what is practised by warriors, wrestlers and swordsmen. This is a more dynamic type of yoga, where holding postures is less emphasised, but instead more repitition of cycles are done. The most common excercise being the Dand and Behtak (commonly known in the west as the Hindu Squat and Hindu Pressup) but there are many more traditional regimes and cycles which are learnt. These build up dynamic strength without the use of weights, increasing power, stamina, agility whilst also maintaining flexibility, the key aspects of a good warrior physique.
Is Yoga a martial art? No, but I see it as the key to building the body of a martial artist which will complement the fighting arts. Since I have been practising it, it has made my body much more fluid, increased my stamina, strength and agility.