If you want to increase mobility, strength, power, or muscle mass, you need to create a pain-free environment from which your body can function. But if you've gotten little to no relief from foam rolling, corrective exercises, and modified variations of the big lifts, you need to learn these trigger point drills.
These simple techniques will ease pain through the legs, hips, and shoulders. And they'll improve your ability to move by tapping into your body's neural response to both pain and dysfunction.
Quick note: These techniques don't "break up scar tissue," but instead spark neurological change to alleviate tightness and pain. Check them out.

1 – Plantar Surface Of Feet

What you need to know about your feet.

The plantar surface of the foot is one of the most sensitive areas of the body. It's made up of multiple layers of local intrinsic musculature, along with neural vasculature in this region. Your feet provide the perfect opportunity to alleviate pain and dysfunction locally AND up the chain into the legs, pelvis, and even the spinal column.

What to use.

Because of the relatively small size of the muscles, distributing tendons and local neuromuscular junctions at the bottoms of the feet, you'll need a tool for trigger point work that matches the size of the targeted region. In this case, a lacrosse ball or even a golf ball – depending on your foot-size.
The bottoms of the feet are anatomically complex, so you need the proper neuromuscular trigger points to yield the highest results in terms of pain alleviation and functional transference.

Locate the right area.

Look for the optimal area that's usually located right under the posterior aspect of the foot's arch. This location is home to the notorious plantar fascia, which gets much of the attention for local pain in this area. But keep in mind the neurological response that you're after. Look deeper anatomically and try to stimulate the neuromuscular junction of the medial and lateral plantar nerves, which will most likely cause the positive response you're needing.

Apply the pressure.

Apply pressure into the ball by distributing your bodyweight through the foot. This area will be hypersensitive, so shoot for a 6/10 relative pain level when self-treating. (On a scale of 1 to 10, with 10 being the highest amount of pressure, go with about a level 6.)
Once you've applied proper pressure over the ball, don't roll the ball up and down the plantar surface, which is a common practice gone wrong. Instead, keep the ball stationary, then extend and fully flex your toes. This is a slow and controlled active remedy that'll place tension and a bit of internal motion on the medial and lateral plantar nerves. This drill has shown promise for alleviating pain and opening up functional ranges of motion.
A little goes a long way here, so spend the time to position the ball perfectly with optimal pressure and take 30-60 seconds flexing and extending all five toes under control.

How to tell if it's working.

First, is your relative pain level reduced? Answering this should give you a clue. And second, use the toe-touch test. Before you even begin this trigger point work, simply test your toe touch (bend over and try to touch your toes). Notice your range of motion. Then after your trigger point work, retest to see if you've gained range of motion.
And while some experts assume using acute trigger point work throughout the bottoms of the feet would have no functional carryover into gross movement, loads of anecdotal studies across thousands of years of therapy in Eastern medicine shows otherwise. People have been getting results from it regardless of what your favorite textbook does or doesn't say.
If you're in the business of pain alleviation and performance enhancement, your focus ought to be on results as opposed to proposed theory. Results are, and will always remain, king.

2 – Posterior Shoulder Girdle

What you need to know about your shoulders.

The back of your shoulders is another neurological hot spot for quick and effective pain alleviation, especially if you've got nagging generalized shoulder pain and tightness in the triceps and upper back.
The true shoulder joint, the glenohumeral joint, is the most biomechanically mobile ball-and-socket joint in the body, and is rarely in need of more isolated mobility, stretching, or soft tissue work. The shoulder is usually just in dire need of more stability to reduce pain and improve performance. You can achieve that through simulation of the neuro-vasculature located in the backside of the shoulder and upper back.
Similar to the plantar surface of the foot, the posterior shoulder girdle is comprised of many smaller intrinsic muscles that work in coordination with one another to yield optimal movement and function. In this small area, we have interactions happening between the posterior delt, the teres group, the triceps, posterior aspects of the rotator cuff, and other scapular stabilizing muscles. This is one of the major reasons the parts of the shoulder are referred to as the shoulder "complex."
Since there are so many adjacent muscles that interact together to create smooth and sequential movement at the shoulder girdle, these muscles have common neurological innervation points. In this region, the two major neuromuscular junction points that you're after are centered on the inferior aspect of the suprascapular nerve and the axillary nerve.

What to use.

With the same goal of acute neurological trigger point release, you'll once again be using a relatively firm ball that meets the size of the tissues and nerves you're targeting. Depending on the relative size of your back and shoulder, use either a lacrosse ball or softball.

Locate the right area.

The sweet spot is under the posterior delt and above the teres group, where the ball can come in contact with as many muscle bellies as possible, but also with the suprascapular and axillary nerves as well. This is the major landmark you'll want to hit.
You can do this standing, but lying down is better because it takes gravity and motor control out of the equation. The simpler you can make the positions that'll help you tap into a parasympathetic response, the better.
Lie on your back with your feet on the ground and with knees and hips bent. Your ball will be in direct contact around these nerves in the back of the shoulder. From this position, apply a 6/10 relative pressure into the ball while slowly moving the arm into controlled elevation.

Apply the pressure.

Don't try to really crank out end ranges of motion here, but move the arm just enough to create some relative gliding actions between the muscles and nerves under the ball's contact point. Concentrate 30-60 seconds here.
See if this technique helped by testing and retesting your authentic shoulder flexion (raise your arms perpendicular to your body). And of course, ask yourself if it altered your pain.

3 – Posterior Lateral Hip

What you need to know about your hips.

With chronic hip tightness and immobility being common, many modalities like foam rolling and stretching have fallen short of eradicating the problem. Sure, spending time decreasing tone of the big hip musculature like the glutes, hip flexors, and adductors is a great starting point, but to truly make an impact on functional transference you need to target more exact areas with a neural plasticity mindset.
By now you'll see a similar trend in the areas you're addressing with trigger point release, they're where multiple muscles and nerves interact with one another locally. They're also easily palpable and locatable areas that external tools like lacrosse balls can positively impact.

What to use.

Caution first and foremost. Though you'll be sensitive to many of these techniques, you'll need to practice this one in particular with restraint to avoid flaring up the region. (This area is near bigger neurological bundles such as the sciatic nerve and peripheral nerve roots of the spine.) So the tool to use is a softer trigger point ball that allows some give – NOT a hard lacrosse ball.

Locate the right area.

The outside of the hip is another anatomically complex area because of what it does: coordinate stability and mobility around the hip joint and connect the pelvis and spinal complex to the lower extremities.
The lateral hip is also a commonly neglected area of self-treatment, as the glutes and hip flexors get all the attention since they're larger, better known muscles of the body. The smaller muscles of the lateral hip – largely the tensor fascia lata, the gluteus medius and gluteus minimus – surround two key nerves, the superior and inferior gluteal nerves. To access these areas, you'll also be addressing the gluteus maximus which attaches onto the lateral hip as well.
By targeting acute neurological trigger point work into the posterior lateral aspect of the hip (which creates a muscular notch that can be easily palpated) you can alleviate pain and regional tightness around the hip complex.

Apply the pressure.

In a side-lying position, place the ball directly under your gluteus minimus located in that muscular notch right above and behind the greater trochanter – an easily palpable bony portion of the femur at the outside of the hip. Place your bodyweight (not all of it) on the ball and achieve no more than a 6/10 relative perceived pain.
From this position, you'll be manipulating the motion of the hip to move both into flexion and extension, and also slight internal and external rotation to place tension and relative motion through the muscular movers and nerves being targeted.
Since these muscles are largely tonic stabilizers of the hip, very little motion will actually be happening here, which is the reason for moving into both rotation and flexion/extension. Spend 30-60 seconds with slow and deliberate hip movements, and make sure to retest hip stability with a balance-based test, as featured in the video, along with detecting whether or not pain was alleviated.