Thirumoolar is the guru for Pranayamam , he revealed the secret of breathing. The ratio of breathing should be 1:4:2 .Normally other pranayama apps teaches you only
Inhale and Exhale , but the secret is once you inhaled the air should stay in lungs for quite some time so that the oxygen is fully absorbed then exhale the CO2. The ratio is for Inhale 1, Holding 4 and Exhale 2.This app operates in 2 modes one is Beginner and another one is Expert.