As I am referring in what follows not to a traditional yoga practice, I'll briefly settle upon why the yoga practice, especially at the beginning, is to be supplemented with other kinds of training. Indeed, there are, basically, yoga methods for development of physical body at all the levels: static strength and endurance, flexibility, coordination and reaction. Cardiovascular and respiratory systems are trained and developed in a course of yoga practice, especially when dynamic styles are used, for example, Himalayan Vinyasa. Static strength and endurance are trained by asanas practice, also there is a significant influence on endocrine, lymphatic and other systems of organism. Respiratory function improves and develops also in prāṇāyāmas practice. Coordination and reaction may be improved by Shiva's dance practice. Then why doing something else? Reasonable question arises. The answer is simple. In order to work through and develop physical body effectively within the frameworks of yogi methods only, one should devote a considerable time to it. To be honest, such practice will take almost all the time. But except physical practices there are also the internal ones, which are the same important, if not more, as those external. For the citified yogi, with work, family and other different activities, the issue of balance in application of time, physical and energy resources under conditions of a modern pace of living is burning. That is why the application of maximally effective, to a certain purpose, kinds of trainings is of a great importance.
According to the mentioned above, the additional training for the beginners is especially actual, as there is, depending on individual peculiarities of an organism, a vivid misbalance in development of any physical quality. Often it's about shortage of strength, endurance and failure to control breath under stress. Which trainings will be useful for overcoming of the restrictions mentioned? Of course, running, swimming, rock climbing, skiing, cycling or gym, for example. All activities enumerated are good, but it may be impossible to apply them regularly, due to, still, time shortage, as well as seasonality, restrictions on the part of knee joints etc. As for me, I started to train under Tabata protocol in order to overcome breath difficulties in yogi practice, the result was vivid and very quick, and all the additional effects in terms of strength increase, endurance and dry muscles were the pleasant bonus. As of today Tabata for me is a great alternative to long cardio workouts.
Now we proceed to a practical side on the issue...