You only need three exercises, a push, pull, and a squat for total strength training. The barbell bench press, the barbell squat, and a dumbbell row will develop everything. Strength training alone fails to complete a program though. You need to get your heart rate up and fight through some burn in the muscles as well. Throw some conditioning in there via intervals. This also gives extra work to your stabilizers, addressing a possible disadvantage of only three movements.
Bracing works the stabilizers. In order to remain fixed during any free weight exercise, your body has to lock in and stay rigid. This explains why you could never squat heavy while standing on a balance beam. You need stability to express strength, therefore the big three do hit the stabilizers.
Perhaps these lifts alone fail to hit them enough though. A day or two after a squat, you may feel sore in the thigh muscles, but rarely in the calves and outer hips. After pull-ups, you may have a sore upper back and biceps, but rarely feel sore in the forearms, and hands. This may give us a sign that these smaller muscles do not receive much of a stimulus like the big muscles do.
Smaller muscle groups do perform less mechanical work during the major lifts. They work to hold positions and not cause movement. This lack of movement seems to decrease soreness, and therefore this litmus test may fail us. Stabilizers simply tend not to get sore.
Still, as an athlete especially, you may wish to address the stabilizers further. Although some would say that we should work them with movement, such as doing hip abduction to work your outer hips, or wrist curls to work your forearms, the anatomy clearly shows that these muscles never adapted for movement. Doing so can harm the joints. Instead, should they need more work, we should use more functional exercises.
Walking with weight, a legendary strongman activity, serves as the ultimate stabilizer exercise. I suggest the huge sandbag bear hug variation. You can make your own. Get a sea bag or something similar at a local Army & Navy store, then stuff it with rubber mulch from Lowe’s or Home Depot. Squat down, bear hug it, stand up, and carry the bag into the vast wilderness. I would suggest against carrying a solid object this way though. If using steel or a rock, carry the weight at your sides. Keep good posture while you walk.
This may sound fun to the warriors among us but feels incredibly brutal. The awkwardness prevents you from assuming the ideal position, which overloads those stabilizers. The compression makes you wheeze to breathe. You could do this interval style, or simply carry it as far as you until you have to set it down. You could also go as far a distance as possible for 3-5 minutes with breaks as needed. No perfect protocol exists, so feel free to experiment. Just work hard and avoid going at it for too long. When you hit your goals for pace and time, either cover more ground the next time or add weight.
As you walk, you have to work very hard to prevent lateral movement. This hits stabilizers such as the hips, shoulders, calves, and core. It works your grip, which includes the entire forearm and hand muscles. It works the entire leg, with the calves naturally working in the right range of motion along with the feet too. It addresses the stabilizers of the upper back such as the trapezius and rhomboids. The core activates intensely due to the unilateral movement of walking, with the obliques on your sides getting plenty of strain.
While many clients will tell me they feel an exercise in a specific group of muscles, they state that walking with heavy weights hits EVERYTHING. Since the major muscles that contribute to walking and holding come into play as well, such as the thighs and back, this elevates your heart rate with so much muscle involved.
You can also perform a farmer’s walk to achieve a similar effect. Dead-lift two dumbbells or weight plates from the floor. Keep the arms straight down at your sides. This option will tend to feel harder on the grip, possibly limiting the overall effect. Although most do not have access to this option, a yoke would work superbly. You can also walk with a barbell across your back, but must exercise caution. When you have to turn to walk another direction, transition slowly. Use the safest option available.
I always considered the “4th exercise” the interval. Intervals get your heart rate up in a way that resistance training cannot approach, since you can involve more muscle simultaneously. Intervals also address the stabilizers further beyond the big three. They make an excellent finisher to a workout.
Consider a loaded carry in your interval repertoire. It works well as a conditioner and intensely works the stabilizing muscles.