I wanted to address the question "is there any religious significance to yoga."
To people who think they should do yoga just for the sake of exercise, I feel is like saying "pray namaz just because it's fard."
Unfortunately many Muslims do pray namaz just for show, or to fulfill a requirement for access to jannah. Before I confuse anyone, let me say that after learning the philosophy behind yoga, my namaz has become longer and longer and longer....because I finally realize the ultimate purpose of namaz....and yes, YOGA TAUGHT ME THAT!
First let me show you the similarities in surya namaskar and namaz (and also the medical reasons why staying in each pose is so important)
1. Tadasana--we open our heart, spine erect ready for the practice ahead.
1. Qiyyam-- we stand erect hands on our navel (an energy powerhouse btw), and with Allah u Akber, try to leave worldly thoughts behind.
2. Uttanasana-- spine is inverted, head close to knees, and in Uttanasana variation, spine is exactly parallel to floor, so the spinal fluids travel from the base to the brain.
2. Ruku-- spine is straight, parallel to floor, we stay here for 3, 9, or 11 tasbeehahs
3. Ardha sirsasana--Knees on floor, raising the tail bone, the forehead on the ground, weight pressing on the peneal gland (third eye) releasing seratonin that " affects the modulation of wake/sleep patterns and seasonal functions (wiki)". This pose is preparationg to Sirsasana, also known as King of Yoga poses.
3.Sajood--Knees on floor, raising the tail bone, forehead is laid to the ground, we stay here for 3, 7, or 11 tasbeehats.
4. Vajrasana--a sitting pose, sitting on heels, toes touching each other, knees together. Meditation is done in this pose along with utilizing several mudras (juxtaposition of fingers in hands)
4.Tassahud--sitting on heels, recite Attahayat, and at Asshaduanna Ilaha Il-Allah!" raising right fore finger.
Now on to the religious significance of yoga: According to Patanjali, yoga is a way to separate the Apparant, from the Reality. His words were further interpreted to "the world from the One Conscious Being or Supreme Being" that is Allah!
We are so immensly lucky that namaz gives us that opportunity to shut out our worldly throughts and think ONLY OF ALLAH! 5 TIMES A DAY! However, how many of us are so hung up on world to do that?
There IS a religious significance to yoga but it's not applicable only to hinduism. It applies to every.single.religion. There are so many rivayat about Prophet Muhammed (s.a.w) staying in sajood for so long that his wives would think he has passed away. He was only meditating, and in the process of meditation, often receiving wahi from Allah subhana watallah.
Did anyone ever wonder why we open our hands to face palms up when making dua? There are two extensions of the heart chakra (powerhouse) in our palms. So literally we're opening our heart to Allah, and showing Him our desires.
May Allah subhana wata-allah help us find Him in this world and in the Hereafter. Ameen.