Unfortunately, there are 
a number of ways we jeopardize 
the health of this important muscle group. For starters, our increasingly sedentary lifestyles are leading to what experts call “gluteal amnesia,” in which the butt muscles become overstretched and underused (read: weak). On the 
flip side, it’s also possible to overuse and overexert these muscles—whether we’re excessively clenching the tush in certain asanas, such 
as Warrior II or Wheel Pose, or pushing too hard while running or hiking. Not only do under- or overworked glutes affect range of motion in the hips and sacrum, but strength imbalances can also lead to instability or pain when we’re 
on our mats. 
(3) This is where I explain the parentheses: The liver and the muscles contain glucose storages. Glucose all chilling together hanging out stored is/are called glycogen. When these storages become full, then glucose will spill over and get stored in our fat cells just like fat does. Why? The glucose “needs to go somewhere”, it’s not just gonna chill circulating around the body. (I’ll explain “needs to go somewhere” in point 6) FAT does not mean looking like Santa, fat is stored energy. Carbs only lead to fat gain when there is a spillover. Fats only lead to fat gain when that fat isn’t used for energy. *keep reading
Let’s say your concentric is 30lbs and you don’t take my advice and keep the 30lbs for your eccentric. Let’s say, I assume you can do 50lbs on the eccentric, but choose to keep it at 30lbs. If you actually started off making light weight feel heavy, that 30lbs would of been around 10–20lbs and my assumption would of been 30lbs. My first assumption was a heavier weight. Your concentric was a heavier weight. What changed? Why did the overall weight become lighter after making light weight feel heavy?
To begin, place the top of one foot on a weight bench (or a chair) and step forward with the other foot out in front of you, similar to a lunge position. Make sure that the front foot is positioned at least at shoulder width and it is far enough away from your body that your knee will not come over your toes when you perform the squat. Put your hands in front of your body (or overhead to make it harder). Perform a “single leg squat” by bending the front leg. The knee of the leg that is up on the bench will go towards the floor. Get it as close to the floor as you can. Do not let the heel of the front foot come up off of the floor. Keeping your heel down will ensure that you engage your glutes and hamstrings in this exercise. You should feel the tension in the hip flexor of the leg that is on the bench when you perform this exercise (you will also feel the muscles of the front leg working). It is important to keep your torso upright throughout the full range of motion. As you go down into the squat, the hip of the back leg is going into extension, which will stretch the hip flexor as well as strengthen it as it stabilizes the hip throughout the range of motion.
"It'’s especially important to eat a carb- and protein-rich meal immediately after a workout," Aceto says. "Right after training, it turns out that your body is really lousy at taking carbohydrates and sending them down fat-storing pathways,"” he says. "So post-training, carbs will be sent down growth-promoting pathways instead."” And when these carbs are combined with a protein source, you'’ve got a strong muscle-feeding combination because carbohydrates help deliver the amino acids into muscles by boosting insulin levels. This anabolic hormone drives nutrients into the muscle cells and kick-starts the muscle-growth process.
At the same time, this also doesn’t mean that primary compound exercises can never be done for more than 8 reps, or that secondary compound exercise can’t be done for 5-8 or 10-15 reps, or that isolation exercises can’t be done for less than 10 reps. Everything can be done in every rep range. However, these are the rep ranges that each type of exercise is best suited for, and where it should ideally be done most of the time.
Are you tired of stretching or rolling out tight hip flexors with no improvements? If you are a runner, weight lifter, or team sport athlete, chances are you have heard a teammate or friend complain about having “tight hip flexors”. Either that or you yourself have had to deal with the problem. The problem with these tight hip flexors is that people will stretch, stretch, and ……..stretch some more (until the cows come home) and get NO RELIEF. This keeps people in a perpetual cycle of ALWAYS stretching their tight hip flexor with no real permanent relief.  The cycle looks something like this:
While there are many reasons why an individual might have weak glute muscles, one of the main causes is that many of us are living increasingly sedentary lifestyles. Many jobs now involve people sitting down for a big part of their day, or after a long day of work we go home and sit on the couch; this means that the gluteus muscles can become dormant more than they should be. Another reason why someone might have weak glutes could be because of poor form and generally over-relying on other muscles during everyday movements, which contributes further to the muscles remaining inactive. 
There is no simple orthosis for the management of isolated paralysis of the hip flexor muscles. While the hip guidance and reciprocating gait orthoses mechanically assist hip flexion (see p. 115), neither is prescribed solely for this purpose. Rather they are prescribed for patients with extensive bilateral lower limb paralysis who also require orthotic support around the knees and ankles.

The hip flexors help balance the posterior pelvic muscles. Three key muscles often become tight and shortened as a result of activities of daily living. These are the iliacus, psoas major, and the rectus femoris. The iliacus and the psoas major are often referred to as the iliopsoas because they share the same insertion at the lesser trochanter of the femur. The psoas minor inserts on the superior ramus of the pubis bone and mainly supports the natural lordotic curvature of the spine, but is only found in about 40% of the population. The psoas major originates on the anterior surface of the lumbar vertebrae and runs over the pubis bone and inserts into the lesser trochanter of the femur. This muscle not only helps to flex the hip, but also has an effect on the lordotic curvature of the lumbar vertebrae. The rectus femoris has a proximal attachment at the acetabulum and inserts into the tibial tuberosity. This long muscle plays a role in both hip flexion and leg extension (Figure 9-4).
This exercise is challenging and will certainly be beneficial even without weights. If you can execute perfect form with your body weight, you can make the exercise harder by adding weights to your hands, by stepping on an unstable surface with your front foot (balance disc, foam pad), or you can place your rear leg on an unstable surface such as a physioball. You should be able to comfortably perform 2-3 sets of 10 reps on each leg before advancing this exercise.