Lunge is a strength training exercise,it trains your quadricep muscles, buttocks and your hamstrings.To increase the difficulty you can hold dumbells in your hands or you can hold a barbell.
How to do a lunge
1.Take a big step
2.Bend your knee and form a 90 degree angle (do not bend your knee over your toe),your other knee should be touching the floor.
3.Return to the starting position and take a step with your other knee.