Exercising dynamically will help to stregthen your core at the same time
A lot of attention gets paid to the core muscles. As a Remedial Massage Therapist I focus on advising clients to strengthen their core in order to protect their spine. The main core muscles, the transverse abdominals, multifidus and the pelvic floor muscles, stabilise the body whilst it performs movements. If the core is not strong then the global movement muscles have to work a lot harder and will try also to stabilise the body. This is where injuries can happen.
The difficulty in learning to strengthen the core, is that if there is weakness in those muscles, it becomes more difficult to isolate them and identify when they are actually being used.
Dynamic exercises like the lunge automatically make use of the core, it is impossible to balance without using your core muscles. The acid test though, comes whilst executing the lunge. With weak muscles it is difficult for the spine to remain erect. As the glutes, transverse abdominals and obliques become stronger and the hip flexors more elastic, staying upright becomes easier. It is essential to keep the pelvis level and the foot and knee in alignment with the hip.
Get your personal trainer to teach your how to lunge in perfect alignment and your core muscles will be getting a dynamic workout. As they get stronger, you will get better at identifying which muscle is which and you will become able to engage your core before performing a movement. You will then be able to exercise the muscle you want to work on effectively and protect your body whilst you are doing it.