Usage of "wenn überhaupt"

Question

Please consider the following sentence:

Muskelaufbautraining ist der sicherste Schutz vor dem Pflegeheim. Doch damit fangen die meisten, wenn überhaupt, erst dann an, wenn gesundheitliche Probleme auftreten.

Which of the following meanings is correct:

1. Most, if not all, people don't start working out until health issues arise.
2. Most people don't start working out until health issues arise, if they do start any workout at all. (In other words: Most people don't start working out until health issues arise, or they don't start working out even then)

Answer 1

With the unmodified example, meaning 2 applies.

For meaning 1 you would have to write:

Die meisten, wenn nicht (sogar) alle, fangen erst mit Muskelaufbautraining an, wenn ...

Other example:

Ich komme erst nachmittags ins Büro, wenn überhaupt.

(I arrive at the office in the afternoon, if at all.)