The Farmer's Walk most likely got its name because it's similar to a farmer carrying buckets of feed for animals. But it has been closely associated with strongman training, probably because of all the times it's been part of "World's Strongest Man" competitions over the years.
Although it can require serious power to hang with those guys, you can use Farmer's Walks to improve your conditioning for your own sport or personal fitness.
Carrying heavy weight for a long period challenges you differently from other cardio programs, because you're engaging your entire body. Your legs are carrying a heavier load than you're accustomed to. Your core has to stay tight throughout. And you're challenging your arms and shoulders to hold on to the weights while your body is in motion for a long period. In short, your conditioning will improve when you add this exercise to your program.
Your gym or training center probably won't have actual Farmer's Walk equipment, but a pair of heavy dumbbells make for a great substitute. All you need are your weights and an open space at least 20 yards long. If you don't have that kind of space, do the best you can with what you have.
The following program is a form of High Intensity Interval Training, involving bouts of max effort activity alternating with brief periods of rest. HIIT challenges you more than traditional steady-state workouts.
The following workout takes only 15 minutes. To make it as effective as possible, give it everything you've got.
Farmer's Walks Workout
Choose a weight you can carry but that's heavy enough to challenge you. You should have to struggle a little to pick up the weights. You might have lifting straps, but don't use them yet.
Start with your natural grip strength. Pick up one dumbbell in each hand. Keep your grip tight, core tight, chest out, back straight and chin up. You could be tempted to lower your chin, but this can cut off your breathing, so look straight ahead and keep your chin up.
Walk until you can't hold the weights any more. Walk your available distance and back. If you can go longer than two minutes, you need to carry heavier dumbbells. If you can't hold them for more than a few seconds, use less weight.
Once you put the weights down, take 30 seconds to catch your breath. After 30 seconds, start again and keep going. Repeat this pattern for 15 total minutes.
If you get close to 15 minutes and can't hold the weights any longer, you can either go lighter or break out your straps.
If you're in great shape, cut the rest periods down to 20 seconds.
If you feel 30 seconds isn't enough, take 45 seconds but work to cut this time as you perform the workout.
Keep track of how long you can go before dropping the weights; your goal should be to improve and walk longer each time. Once you can go past two minutes, use heavier dumbbells.
After 15 minutes, take two minutes to cool down by walking the distance of your path without any weight followed by some stretching.
If you perform this routine two or three times a week, you should notice improvements in your conditioning and grip strength within a few weeks.