Mobility is always a cause for concern especially when someone new takes up weightlifting. There are the exceptional cases where someone is flexible enough to hit the positions the coach wants them to hit easily and in particular the start and receiving position. This is because in terms of joint angles, both of these positions require the joints to be flexed till an acute range of motion which may be difficult with the lack of mobility and flexibility. In that bottom position, the ideal position requires you to have the weight either overhead or on your shoulders, with your shoulders and hips under that weight and your feet under your hips to create maximum stability when receiving the weight. So, here are some common areas which many of us (including myself at times) have issues with and stops us from adopting a less-than-ideal position at the bottom of a snatch or clean when receiving a weight.
1. Thoracic Extension
When at the bottom position of the snatch or the clean, the combined centre of mass of the weightlifter-barbell system is now shifted to somewhere in the upper portion the ribs (for the clean) or just slightly above the shoulders in the snatch. This means that all the weight is supported at that point. This is also key to keeping the weight in line with the hips and feet. However, a stiff thoracic spine is detrimental to keeping that alignment. Not being able to achieve decent thoracic extension would cause the centre of mass of the system to be shifted forward and the stability in supporting the weight in the shoulders would then be lost.
The basics for increasing thoracic mobility are the use of bak-balls or foam rollers. But the missing point about doing these mobility drills for the thoracic region is to allow the structures around the rib cage to relax. Many do foam rolling of their upper backs in the hope of improving thoracic extension but end up keeping the thoracic region "crunched". This does not add to increase the mobility of your rib cage. Mobility involves motor control as well. So keeping your rib cage rounded while trying to roll the muscles in the upper back out will not improve the motor control. Keeping the thoracic spine extended and maybe trying to work some breathing in may facilitate improving the mobility much better and give you better control over improving the movement of the rib cage.
2. Elbow Flexion
Elbow flexion is the action of bringing the forearm close to the upper arm. Many a times, this is seen as an issue because it results in us not being able to keep our elbows up in the rack position for a front squat or when receiving a clean. Not keeping the elbows up will cause the "platform" that we rest the bar on to be smaller and increases the tendency to lose the bar forward easily if it does not sit behind the shoulders.
Image from All Things Gym.
To resolve this, effort needs to be targeted first in the triceps both at the proximal (close to the shoulder) and distal (close to the elbow) attachments of the muscle. Working on loosening up the proximal attachment of the tricep will ensure that the elbows coming up during the receiving of the weight in that rack position will not cause the scapula to be pulled too far forward. For the distal end of the triceps, lengthening the portion of the tendon will allow more flexion to occur and relief the strain on the forearm muscles, subsequently saving the wrists.
3. Ankle Dorsiflexion
Getting low in the squat position or bottom position requires a decent range of motion from the ankles in terms of dorsiflexion. Thus, this is a standard one that many coaches will say that you need to work on. Yes and no. I will discuss the yes part first by looking at common causes for the lack of range of motion in ankle dorsiflexion. The newcomer in weightlifting has probably also spent alot of time doing activities such as sitting, walking, running, tip-toeing etc, which shortens the calf muscles to a certain extent. Unless you come from an Asian country where you are born to adopt a squat position more of the time, then you probably will experience the lack of range of motion in dorsiflexion. Similarly, sitting down too long (especially if your feet do not touch the ground completely) results in your calves being shortened due to gravity. Sorting out those causes will help slow down the detrimental effects of your lifestyle on your calves.
So knowing that the calves are shortened and that results in the limited ankle dorsiflexion, many assume that stretching the calves out will definitely help in increasing the range of motion of the ankles. Yes and that's also in line with what I mentioned earlier with the causes of limited ankle dorsiflexion. Reducing the effects of your lifestyle on the range of ankle dorsiflexion can be supplemented with stretching the calves out. However, many loosen the calf muscles up but yet can't get good ankle dorsiflexion. This is due to the other structures that limit this range of motion. Apart from the ankle joint and the ligaments which need to be mobilised, many neglect the anterior structures of the ankle joint, in particular the tendons of the tibialis anterior and the other muscles involved in ankle dorsiflexion. Imagine your ankle is a hinge and a ball is stuck in the front of your ankle and you are trying to close the hinge. The ball prevents this from happening and this is the case of the anterior compartment of the ankle.
4. Knee Flexion
To allow you to get into a better bottom position in the squat (whether it's a front, back or overhead squat), range of motion in the lower limb joints are critical and mobility in these joints are as important. So at the bottom, not only is ankle dorsiflexion important as mentioned, but knee flexion is also one of the contributing factors to adopting a good bottom position. Especially in the full movements, the knee is placed into extreme flexion to firstly allow the hips to sit down as low as possible and secondly allow them to be located over the feet as much as possible. The structure of a Chinese lifter is suited to easily meet this position due to the length of the lower leg and the femur (thigh bone). However, not all of us are built like the Chinese and we have very individualised cases of lower leg and femur length. However, knee flexion is critical in any case to allow the hips to be situated nicely over the feet and close to the ankles.
To increase the range of motion, the areas that need to be targeted are basically not only the quads but the structures around the knee cap such as the patella tendon , the quadriceps femoris tendon, and even anterior structures at the proximal end of the lower leg (i.e. tibialis anterior etc).
Remember, every individual is going to be different in terms of segment lengths. Hence, the demands for mobility is different for different areas of the body. Understanding ratios between segments is crucial to helping understand how to adopt an ideal position for the individual and subsequently highlights the areas of mobility which need more work on. These are just some of the common areas which people have mobility issues with but not all of you will have to do the same things to improve on these areas.