All ... ing forms in your sentences are ' gerunds '
![Smile [:)]](/emoticons/emotion-1.gif)
If the ... ing form serves as an adjective then it is ' present participle ' instead. But it seems that all the above sentences serve only as ' noun '
It is better to say ' She has improved her swimming through practice ' . To use a phrase in front and separated by a comman normally happens on a sentence where the ' phrase ' is an adj modifying the subject.
eg. He was thrilled when he was asked to do public speaking.
Being asked to do public speaking, he was thrilled.