In order to validate your account, please either send an email from your .mil email address or send in a snapshot of your military ID to our customer service help desk. Blacking out rank and or post is acceptable. In either case, please include the civilian email address or whichever email address you have registered with Onnit.com somewhere in the message body so we know which account to verify. Please setup an account with Onnit.com prior to submitting your request.

Make no mistake: Eating for muscle is just as important as lifting for muscle. The foods you grab in the morning on the way to work, the meals you pack for lunch and mid-afternoon, what you put into your body immediately following your workout, and your final meal of the day impact your results as much as, if not more than, the number of reps you squeeze out at the end of a set. But in reality, it can be tough to stick to a "“clean"” diet when you'’re busy. We know that adding another layer of complexity to life in the form of reading food labels and studying ingredient lists just isn'’t an option for most of us. Not to mention actually preparing all those healthy meals.
The exercises that allow you to use the greatest amount of weight are the ones that help you build muscle the fastest. These also happen to be the lifts that allow for the greatest percentage of increases in loading. We’re talking compound (multi-joint) exercises here, done with free weights. You’re not going to grow at nearly the same rate with a workout comprising machine exercises and isolation movements.
Elsa Pataky's trainer, Fernando Sartorius, says that focusing on squeezing your glutes while performing a booty-blasting exercise allows you to activate the muscle group to their maximum potential. Cameron Diaz's trainer, Teddy Bass, founder of the trademarked booty-sculpting program called Rock Bottom Body, says you should get into a bridge position and memorize what it feels like to really engage your buns—and then try to feel that burn every time you work your butt. The point: Thinking about squeezing your glutes (and actually squeezing them) while strength-training helps you work the muscles in your butt harder.
(4) Insulin is a fat storage hormone - this isn’t true, okay kinda. Like I mentioned, both insulin and protein trigger insulin. If insulin was the issue than high protein intakes should has a worse reputation beyond what it currently has. Insulin has a job of transporting nutrients into cells. Carbs have a more direct connection to insulin than protein, so when carbs are consumed, insulin is spiked higher. Insulin will take the carbs (sugars) and transport them into cells for energy and then the rest into glycogen to save for later. If glycogen is full, then insulin still has a job to do. It doesn’t just float around dumb founded. It takes the carbs (sugars) and stores then into fat. It’s smart like that. But, we abuse that system by eating too many carbs and being in a surplus. The body doesn’t want to convert carbs into fat, that’s what fats are for, yet we abuse and do it anyways.
The sartorius originates at the ASIS and proceeds to traverse obliquely and laterally down the thigh to eventually insert at the anterior surface of the tibia, just inferomedial to the tibial tuberosity, as part of the pes anserinus. In addition to flexing the hip and knee, the sartorius aids in the abduction of the hip. It is innervated by the femoral nerve (i.e., the posterior division of L2 and L3).
Eating the right carbs is important too. Carbohydrate is stored in your body in the form of glycogen. Glycogen in the muscles is an important fuel reserve during intense physical exercise or in times of energy restriction – protein sparing. It is best to restrict or to keep away from junk carbohydrates such as sweets, cakes, and biscuits, and stick to foods like porridge, pasta (wholemeal), rice (brown), bread (wholegrain), and cereals (try to choose the versions with low or reduced sugar and salt). For more on carbohydrate and the effect of sugar on the body, click here.
© 2019 Condé Nast. All rights reserved. Use of and/or registration on any portion of this site constitutes acceptance of our User Agreement (updated 5/25/18) and  Privacy Policy and Cookie Statement  (updated 5/25/18). SELF may earn a portion of sales from products that are purchased through our site as part of our Affiliate Partnerships with retailers. Your California Privacy Rights. SELF does not provide medical advice, diagnosis, or treatment. Any information published on this website or by this brand is not intended as a substitute for medical advice, and you should not take any action before consulting with a healthcare professional.   The material on this site may not be reproduced, distributed, transmitted, cached or otherwise used, except with the prior written permission of Condé Nast. Ad Choices 
Site enhancement oil, often called "santol" or "synthol" (no relation to the Synthol mouthwash brand), refers to oils injected into muscles to increase the size or change the shape. Some bodybuilders, particularly at the professional level, inject their muscles with such mixtures to mimic the appearance of developed muscle where it may otherwise be disproportionate or lagging.[54] This is known as "fluffing".[55][56] Synthol is 85% oil, 7.5% lidocaine, and 7.5% alcohol.[55] It is not restricted, and many brands are available on the Internet.[57] The use of injected oil to enhance muscle appearance is common among bodybuilders,[58][59] despite the fact that synthol can cause pulmonary embolisms, nerve damage, infections, sclerosing lipogranuloma,[60] stroke,[55] and the formation of oil-filled granulomas, cysts or ulcers in the muscle.[59][61][62] Rare cases might require surgical intervention to avoid further damage to the muscle and/or to prevent loss of life.[63]
Take a step back and think about where you spend most of your day. If you're a young athlete, you probably spend most of your time at school or maybe work or practice and  even a little time at home, if you're lucky. Now think about what position your body is in during those periods. I would bet that you spend most of your day sitting down. You may walk to class or run in practice, but the majority of your day is spent in a seated position.
But muscle can’t turn into fat, just like mud can’t turn into gold. If you quit lifting, your muscles mass will decrease over time because there’s no training to stimulate your body to keep it. And your body-fat level will increase if you don’t start eating less (since you burn less). The obvious solution when you stop lifting is to also stop eating so much.

Protein, you may have heard, is what your muscles are made of. Well, not quite. The amino acids that make up protein are the building blocks of muscle, and your body needs—not wants, needs—these substances during and after training for repair and recovery. It breaks down the protein into the respective aminos, uses them for their various functions, and then you convert what doesn't get used. I break down a lot of tissue in my daily workouts, so balancing it out with adequate amounts of protein throughout the day is important.
(1) Water - I drink this all the time. Mainly in the morning. Doesn’t it make sense to hydrate upon waking up? I use to get nauseous, but that was because of a poor “diet”/food choices. Now, it’s like a filtering fluid at this time of day (morning). I drink it all day, but I have like 1 water bottle every hour. It’s easy to remember and to do (well, for me). We should aim for around 100oz of water, consuming all this in one time would suck. So “timing” water (which is a nutrient) is considered “nutrient timing”.

The materials and information provided in this presentation, document and/or any other communication (“Communication”) from Onnit Labs, Inc. or any related entity or person (collectively “Onnit”) are strictly for informational purposes only and are not intended for use as diagnosis, prevention or treatment of a health problem or as a substitute for consulting a qualified medical professional. Some of the concepts presented herein may be theoretical.
Achy knees are often written off as an inevitable side effect of getting older. And while it’s true knee pain has many age-related causes (namely, arthritis), chances are weak glutes are a big part of the problem, Kline says. If you’ve been diagnosed with arthritis, strengthening your glutes can at least help offset some of the pain you might experience, she says.
Don’t get us wrong—cardio is important for keeping your body fat down and keeping your heart health in check. (Bonus points if you run or bike, since outdoor exercise is linked to better energy and improved mental health.) But when it comes to building muscle, hitting the treadmill won't help you much. “Every component of exercise, minus cardio, can help with muscle hypertrophy,” which is the scientific term for muscle building, says Michelle Lovitt, an exercise physiologist and trainer in Los Angeles. “Cardio tends to burn calories and puts your body in a deficit, which is great for leaning out, but not building mass.”
2-4 Minutes Rest: Ideal for “tension exercises,” which includes most primary compound exercises. I personally take 3 minutes for the big stuff, sometimes going into the 3-4 minute range depending on exactly what I’m doing and what I feel like I need at the time. Since making strength gains is the main focus of these exercises, longer rest periods like this will be optimal for making it happen.
How to do it: Start by stepping forward into a lunge with your left foot. Place your right forearm to the ground and your left elbow to the inside of your left foot, and hold the stretch for two seconds. Then place your left hand outside of your foot and push your hips up, pointing your front toes up. Return to standing position and repeat by stepping out with your right foot. Continue alternating sides.
“Exercises such as single leg squats, regular squats, deadlifts, monster walks, side laying leg lifts, step-ups and reverse planks are some of the exercises that can strengthen the muscles," says Schulz. "You can also try a challenging lunge circuit, split squats, and deadlifts for some major toning." (And of course, if you need any further ideas, check out our roundup of the 17 best glute exercises out there.)
You see, there is only so much muscle that the human body is capable of building in a given period of time. So, if you supply your body with MORE calories than it’s actually capable of putting towards the process of building new muscle… it’s not going to magically lead to additional muscle being built. It’s just going to lead to additional fat being gained.
Bodybuilding became more popular in the 1950s and 1960s with the emergence of strength and gymnastics champions, and the simultaneous popularization of bodybuilding magazines, training principles, nutrition for bulking up and cutting down, the use of protein and other food supplements, and the opportunity to enter physique contests. The number of bodybuilding organizations grew, and most notably the International Federation of Bodybuilders (IFBB) was founded in 1946 by Canadian brothers Joe and Ben Weider. Other bodybuilding organizations included the Amateur Athletic Union (AAU), National Amateur Bodybuilding Association (NABBA), and the World Bodybuilding Guild (WBBG). Consequently, the male-dominated contests grew both in number and in size. Besides the many "Mr. XXX" (insert town, city, state, or region) championships, the most prestigious titles[according to whom?] were Mr. America, Mr. World, Mr. Universe, Mr. Galaxy, and ultimately Mr. Olympia, which was started in 1965 by the IFBB and is now considered the most important bodybuilding competition in the world.
Copyright © 2019 Leaf Group Ltd. Use of this web site constitutes acceptance of the LIVESTRONG.COM Terms of Use, Privacy Policy and Copyright Policy. The material appearing on LIVESTRONG.COM is for educational use only. It should not be used as a substitute for professional medical advice, diagnosis or treatment. LIVESTRONG is a registered trademark of the LIVESTRONG Foundation. The LIVESTRONG Foundation and LIVESTRONG.COM do not endorse any of the products or services that are advertised on the web site. Moreover, we do not select every advertiser or advertisement that appears on the web site-many of the advertisements are served by third party advertising companies.
See what I mean? Notice, how I said the “fatigue of failure”. This is because one must interpret their fatigue properly. (1) Some go past failure thinking something magical is going to happen, when only damage will occur. (2) Some feel slight fatigue, aren’t close to failure, and should keep going to enter in the actual sensation that matters: failure. (3) Some are very close to reaching fatigue, but misinterpret the sensation as failure and stop, when they were only moments away from feeling something they never felt before.
It’s a lofty goal: Gain 10 pounds of muscle in just one month. While such results are aggressive and can’t continue at the same torrid rate indefinitely, we’ve seen firsthand individuals who’ve followed our mass-gaining programs and reached double digits in four short weeks, averaging gains of 2-3 pounds a week. Trust us, it can be done. But if there’s one thing such a bold goal needs, it’s an ambitious training and nutrition strategy. In regard to nutrition, don’t even think about taking that aspect lightly. You can work out all you want, but if you don’t ingest adequate calories and macronutrients, you won’t build muscle. What and when you eat is paramount to your results, and you’ll find all you need to know about gaining mass in a short amount of time in our bulking diet meal plan. 

I loved football and football culture. But bodybuilding is more than a culture—it's a lifestyle. You can't do it sloppily and succeed, especially if you have high-level competitive ambitions like I do. Your results speak for themselves, and your hard work pays off in ways that you can see, feel, and measure. There's nothing like the feeling when it all comes together.
“Imagine you've fasted for over eight hours,” he says. “At breakfast, you're firing your metabolism off really high. If you don't eat for another five hours, your metabolism starts to slow right down and you have to try and kickstart it again with your next meal. If you eat every two and a half to three hours, it's like chucking a log on a burning fire.”
The two workouts listed above are completely free and highly recommended. If, however, you’re looking for additional workouts, my book – Superior Muscle Growth – contains ALL of the muscle building routines that I’ve personally used and designed for others (11 different workouts, 40+ different versions). Feel free to check it out to learn more about what’s included.
There are many camps within the weight training fitness community. We have bodybuilders, Crossfit athletes, powerlifters, Olympic lifters, and strongman athletes just to name the most popular ones off the top of my head. One thing they all have in common is that they all use resistance to achieve a particular goal. They all also “share” particular exercises. Most resistance-training athletes do barbell squats, overhead presses and deadlifts. I can write pages of differences between each of the disciplines I listed above and I can also write quite a bit about their similarities but one form of resistance training is MORE different than the others. Bodybuilding is the only sport that judges the appearance of the athlete rather than their performance. This may be why bodybuilders tend to get poked at the most.
Lie on your left side and position yourself so that your bottom forearm is directly under your armpit and your legs are straight with feet stacked. Brace your core and lift your hips in the air, forming a straight line from ankles to shoulders. Next, raise your top leg, without bending your knee, a few inches into the air. Hold for 3-5 seconds, lower the leg, and repeat. Complete required reps then switch sides.

Foundational supplements are often overlooked for building muscle, because they work behind the scenes. In actuality, foundational supplements are important to take for building muscle, because they assist with overall health and wellness and contribute to the effectiveness of other muscle building supplements.* Some of the top foundational supplements are:

This test measures a participant's ability to stand up from a seated position as many times as possible in a thirty-second period of time.[2] Testing the number of times a person can stand up in a thirty-second period helps assess strength, flexibility, pain, and endurance,[2] which can help determine how far along a person is in rehabilitation, or how much work is still to be done.
This test measures a participant's ability to stand up from a seated position as many times as possible in a thirty-second period of time.[2] Testing the number of times a person can stand up in a thirty-second period helps assess strength, flexibility, pain, and endurance,[2] which can help determine how far along a person is in rehabilitation, or how much work is still to be done.

Do Belgian squats (or "single leg squats") with a dumbbell. Hold out in front of your chest a dumbbell using both hands. Standing in front of a bench, lift your right leg back so that it's parallel to the floor and resting comfortably on the bench. Bend into a squat using the left leg, so that the right knee almost hits the floor. Lift and repeat 3 x 8. Repeat using opposite leg.


How to do it: Balance on your right foot, keeping your midsection tight and shoulders back and down. Bend at the waist with both of your hands out to the sides and extend your left leg back as you fire the left glute. Your shoulder and heel should move together, forming a straight line. Return to starting position and switch legs, performing a set of 10 on each leg.
  Take note to see if the thigh rests down parallel to the ground (Picture 2) or if it stays up in the air (Picture 1) (You will need someone to be nearby to see what your leg does). Perform on both sides and compare. If the thigh does not stay raised up in the air then there is no true hip flexor tightness and stretching does not need to be performed. If one of the thigh/legs stays up noticeably higher than the other, then stretching will need to be performed. If your leg is able to hang down comfortably parallel to the ground or lower then you passed the test!

How to do it: Firmly plant your feet on the platform of a Power Plate machine, and turn it on to the vibration setting you’re comfortable with. Exercise your full range of motion as you “pulse” by bending your knees slightly at 80-90° in a squat position. “Vibration training uses time under tension, so complete squat pulses for 30-60 seconds,” Reames says. This is one set. Because the Power Plate works by vibrating across three planes: vertical, horizontal, and up and down, your body is forced to make microadjustments, which can improve your strength, power, flexibility, balance, and muscle tone.
How to do it: Stand with feet just outside the shoulders and hands behind your head. Squat, keeping your knees behind your toes and squeezing your glutes. After holding this position for two seconds, jump vertically. Pull the toes to your shins in midair to prepare for landing. Land in the starting squat position, hold three seconds and repeat for 10 reps. Be sure to land softly, with the hips back and down.
(5) Glycogen levels. Ever heard of Keto Diet? This diet focuses on little to no carbs. Why? Glycogen levels. Most people eat too much food and most of these foods are carb based. Which means most people have filled glycogen levels. Which means most people are having glucose spill over into being stored as fat. By dropping carbs, we stop carbs from being stored as fat. By dropping carbs, we allow glycogen to become depleted which allows another opportunity to treat carbs better. By dropping carbs, we drop our calories, which should help one enter into a calorie deficit and it’s this deficit that helps more than anything. Make sense?
It has been argued that purposely overtraining for a brief period can be beneficial. One article published by Muscle & Fitness magazine stated that you can "Overtrain for Big Gains". It suggested that if one is planning a restful holiday and does not wish to inhibit their bodybuilding lifestyle too much, they should overtrain before taking the holiday, so the body can recuperate and grow during the prolonged rest period. Overtraining can be used advantageously, as when a bodybuilder is purposely overtrained for a brief period of time to super compensate during a regeneration phase. These are known as "shock micro-cycles" and were a key training technique used by Soviet athletes.[53]
Athletes with relative shortening of the hip flexors and accompanying weakness of hip extensors will exhibit decreased hip extension at terminal stance phase or “toe off.” Athletes who lack hip extension may also exhibit related limitation in great toe extension. Often these athletes will show decreased wear under the great toe aspect of their shoe sole and relative increased wear under the more lateral toes. These athletes may also demonstrate increased hip flexion at initial contact or “heel strike” in an effort to make up for the shorter stride length caused by limited hip extension. In patients with knee instability this will contribute to hyperextension or “giving way” of the knee.13

How do I know if my weights are heavy enough? Check your form. This workout involves many repetitions of the same exercise and you will know you are using the correct weight if your form stays consistent between the first part of a repetition set and the end. For example, a row from plank should look the same on repetition number 10 as it does in repetition number two, even if the effort is much greater. If your form is wobbly by the end, drop down the weight amount until you’re able to find consistency. Don’t forget that working with weights is not an all-or-nothing proposition. Your body also provides resistance. Try our 9-Minute Strength Workout for a weight-free option. 

Most typical bodybuilding programs have way too many sets and reps and use the wrong exercises. However, if you lower the total volume, go heavier, and use compound movements as I’ve outlined above, there is nothing wrong with a body-part split for advanced lifters. In fact, it’s often less stressful to the joints than your average upper/lower split.

“Imagine you've fasted for over eight hours,” he says. “At breakfast, you're firing your metabolism off really high. If you don't eat for another five hours, your metabolism starts to slow right down and you have to try and kickstart it again with your next meal. If you eat every two and a half to three hours, it's like chucking a log on a burning fire.”
Aim to eat roughly 250 to 500 extra calories per day. To make sure that any weight gained is from muscle, Fitzgerald recommends that the bulk of those calories come from protein. In a 2014 Pennington Biomedical Research Center study, people who ate a high-calorie diet rich in protein stored about 45 percent of those calories as muscle, while those following a low-protein diet with the same number of calories stored 95 percent of those calories as fat.

Make no mistake: Eating for muscle is just as important as lifting for muscle. The foods you grab in the morning on the way to work, the meals you pack for lunch and mid-afternoon, what you put into your body immediately following your workout, and your final meal of the day impact your results as much as, if not more than, the number of reps you squeeze out at the end of a set. But in reality, it can be tough to stick to a "“clean"” diet when you'’re busy. We know that adding another layer of complexity to life in the form of reading food labels and studying ingredient lists just isn'’t an option for most of us. Not to mention actually preparing all those healthy meals.

The gluteus maximus can be your best friend when it comes to safely 
performing backbends. Yet overusing this big muscle by clenching your butt as you backbend can lead to irritation and injury in the spine and sacroiliac (SI) joint. In order to mitigate excessive spinal compression in backbends, it’s helpful to use the buttocks and adductors (inner thighs) to support the weight of the pelvis, hips, and spine. Work on the following actions:
(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
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.
How to do it: Start by stepping forward into a lunge with your left foot. Place your right forearm to the ground and your left elbow to the inside of your left foot, and hold the stretch for two seconds. Then place your left hand outside of your foot and push your hips up, pointing your front toes up. Return to standing position and repeat by stepping out with your right foot. Continue alternating sides.
Choosing the right size stability ball matters—if you’re using one that’s too big or small, your body positioning could be wonky, making the move less effective, says Henwood. For the V-Lift and Bulgarian Split Squat in this workout, choose a ball that naturally has your legs at a 90-degree angle when you sit on it (your hips should be at the same height as your knees). You may need a smaller option for the Hamstring Press—opt for one that you can comfortably hold between your legs so it stays put for every rep.

  Take note to see if the thigh rests down parallel to the ground (Picture 2) or if it stays up in the air (Picture 1) (You will need someone to be nearby to see what your leg does). Perform on both sides and compare. If the thigh does not stay raised up in the air then there is no true hip flexor tightness and stretching does not need to be performed. If one of the thigh/legs stays up noticeably higher than the other, then stretching will need to be performed. If your leg is able to hang down comfortably parallel to the ground or lower then you passed the test!
A sedentary lifestyle can lead to having weak and tight hip flexors as they are always in the shortened position. Tight hip flexors can lead to a limited range of motion, poor posture, lower back, and hip pain, and even injuries. These muscles need to get a workout when you are standing and doing movements such as raising your leg to climb stairs, run, or ride a bicycle.​
Do Belgian squats (or "single leg squats") with a dumbbell. Hold out in front of your chest a dumbbell using both hands. Standing in front of a bench, lift your right leg back so that it's parallel to the floor and resting comfortably on the bench. Bend into a squat using the left leg, so that the right knee almost hits the floor. Lift and repeat 3 x 8. Repeat using opposite leg.

“Imagine you've fasted for over eight hours,” he says. “At breakfast, you're firing your metabolism off really high. If you don't eat for another five hours, your metabolism starts to slow right down and you have to try and kickstart it again with your next meal. If you eat every two and a half to three hours, it's like chucking a log on a burning fire.”


It’s a lofty goal: Gain 10 pounds of muscle in just one month. While such results are aggressive and can’t continue at the same torrid rate indefinitely, we’ve seen firsthand individuals who’ve followed our mass-gaining programs and reached double digits in four short weeks, averaging gains of 2-3 pounds a week. Trust us, it can be done. But if there’s one thing such a bold goal needs, it’s an ambitious training and nutrition strategy. In regard to nutrition, don’t even think about taking that aspect lightly. You can work out all you want, but if you don’t ingest adequate calories and macronutrients, you won’t build muscle. What and when you eat is paramount to your results, and you’ll find all you need to know about gaining mass in a short amount of time in our bulking diet meal plan.

Bodybuilding developed in the late 19th century, promoted in England by German Eugen Sandow, now considered as the "Father of Bodybuilding". He allowed audiences to enjoy viewing his physique in "muscle display performances". Although audiences were thrilled to see a well-developed physique, the men simply displayed their bodies as part of strength demonstrations or wrestling matches. Sandow had a stage show built around these displays through his manager, Florenz Ziegfeld. The Oscar-winning 1936 musical film The Great Ziegfeld depicts the beginning of modern bodybuilding, when Sandow began to display his body for carnivals.
This leaves you frustrated and yes……….with consistently tight hip flexors.  A crucial step is often missed with trying to stretch away tightness or pain. Before anymore blame is placed on the hip flexor muscle, it needs to be properly assessed. Then after an assessment is performed you can determine what the right hip flexor exercise for you to do is.
Expert tip: “Optimum form and range of motion for the squat is very dependent on your physicality, structure, joint integrity, limb length, strength, flexibility, and current condition,” Reames says. Your range of motion is 90° max at the knee. Some guys will be able to go lower than this, but not everyone will squat to parallel, he says. And that’s totally okay. “Stick to form and the appropriate resistance levels for you; the squat is still one of the best and simplest moves for overall strength, building lower-body muscle, core strength, and athletic performance. 
The hip flexors are prone to becoming tight and shortened. They are active with each step that we take, especially while running. A major contributing factor to their tightness is that based on their location and anatomical attachments, when we sit, we are putting the hip flexors in a shortened position. Unfortunately, many of us spend a good part of our day sitting. The combination of sitting and heavy use of the muscle during activity causes it to become shortened. A shortened muscle does not generate as much power as a normal length muscle is capable of. The shortening and weakening of the hip flexors creates a muscle imbalance in the hip, which can cause problems in other parts of the body.
The hip flexors are a group of muscles in the front of the hip that act to lift the knee and bring the thigh towards the abdomen. The major muscles making up the hip flexors that we will focus on are the iliacus and the psoas, or the iliopsoas and the rectus femoris. The rectus femoris  is a “two joint muscle” because it crosses both the hip and knee joints. As a group, the hip flexors have attachments on the lumbar spine, the pelvis, and the femur. In addition to their major function of flexing the hip, their attachment on the spine makes them an important part of the core muscles and spinal stabilizers.
×