I'm on an HHMI (Howard Hughes Medical Institute) physician scientist path, a privately funded path that begins as a summer fellowship between the first and second year of medical school, and then if successful, an additional year either between second and third or third and fourth year. These paths are an alternative to MSTPs (medical scientist training programs leading to dual MD/PhD degrees). They typically cater to the same quality and character students as MSTPs, meaning a heavy research background and a passion for a career in bench science after residency. I plan to pursue a research oriented residency, meaning an additional year or two of residency with committed research time, kind of like having a post-doc intertwined with your residency.
All that said, there are many ways to do bench research with an MD. Even if you just do research on the side, so long as it's productive, meaningful, and yields lasting skills, you can continue those pursuits throughout your career and compete for grants as an attending at an academic institution. The best advice is to find a mentoring attending at your local institution and follow that physician's advice to reach your goals. There are a million ways to skin a...culture. 😉