I you wanna know if any part of your body were used in your swimming, just touch them. If it is warm even in the cold water, then the muscle groups there succumbed to workouts. If cold = nothing. I swam all styles, but find that swimming alone can't really help you in getting a flat stomach. Abdominals are divided into upper, lower abdominals, intercostals (spelling) and obelique (spelling). All of these has different sets of exercises to tone them. 2 side lines? Try to hold a long stick, legs shoulder apart and twist your body on the waist. Maintain your vision in front. Only swing your body using waist. During each swing, tense your stomach and at the end of the swing, press hard and then release, not fully, but still tensed. In time, you'll have slim waist.

Smallbug! when are we swimming again? What happened to Sky and Axley?