The Smith machine gets a lot of criticism, but it has its place. A million very large bodybuilders who make it part of their training can't be wrong.
Problem is, this piece of equipment is only found in commercial gyms. The solution? The scrape-the-rack method. You'll get a similar (arguably better) training stimulus.
1. Stiff-Leg Deadlift
Scraping the rack is a great way to place extra tension on the hamstrings and glutes. Moving your feet slightly forward while leaning back and pulling the bar against the rack allows you to get a bigger/better stretch on the posterior chain. It's a great alternative to a conventional stiff-leg deadlift.
2. Bent-Over Row
Struggle to feel your lats when you do bent-over rows? This will solve that problem quickly. Pulling the bar against the rack better isolates the lats. They're under constant tension throughout the rep. This is one of the best rowing variations you've never tried.
Place your toes in front of the bar so you're off balance and leaning against the rack. Get a big stretch at the bottom of every rep to maximize the ROM. By sliding the bar against the rack, you create more resistance and isolate the traps far better than conventional barbell shrugs. Use straps and go heavy for high reps.
4. Strict Press
This is one of the best pressing variations for lifters with cranky shoulders because it ensures a perfectly vertical bar path. Scraping the rack adds a significant amount of additional resistance without actually increasing the weight. It also better isolates the delts as you eliminate any cheating or compensation from other muscles (such as your pecs).