Here are five thoughts and ideas to round out the week. If it's confusing, I apologize, the two neurons in my brain don't always synapse real well.
1. Head position can slow you down and lead to greater risk of hamstring pulls in sprinting, especially during the acceleration phase. Imagine a sprinter if you will. At the start the athlete is driving out (acceleration phase), he/she should be pushing their center of gravity (good forward lean, driving out, positive shin angle). If the head comes up too quickly, it throws on the extensor reflex, activating the spinal erectors, forcing the pelvis into a greater anterior tilt, inhibiting the glutes, and overloading the hamstrings.
The chin needs to stay tucked into the back of the neck (think: try to make a double chin). Eyes will be looking at the ground, because the torso has a good forward lean. A solid chin tuck, will allow the glutes to work at a higher level. It's really just maintaining a neutral spine. Check out this video of Maurice Greene, and pay close attention to his head position. side note: The sprinter to his left must not have heard the starting gun.
2. Staying on the topic of head position, it's easy to tell if someone isn't finishing their deadlifts or RLD's with their hips. Watch the head at the lock-out position. If the chin tucks into the neck at lock-out chances are the glutes finished the move, the way it should be. If the head is looking up, then the person is more than likely just hyperextending their back, with no use of the glutes at all.
3. Another exercise that needs to be paid close attention to as far as head position goes is Glute-Ham Raises. If the athlete/person is neck is extended and the head is up, the spinal erectors and hamstrings will be doing most of the work. Again the chin needs to be tucked to get greater activity out of the glutes.
4. Ankle dorsiflexion plays a vital role in the ability to sprint powerfully and efficiently, and inability to properly dorsiflex can be a main culprit to hamstring pulls and low back tightness during athletic activities.
5. Why are people and athletes with patellofemoral pain prescribed to do squats with their back to a stability ball against a wall.
To me it's putting the majority of the work on the rectus femoris, which is often times a major player in causing knee pain. Plus it's like doing something like a closed-chain knee extension... I don't know it just seems pretty stupid to me. Imagine if you could somehow make the ball disappear while someone was doing a set; they would fall right on their ass. How is this helping improve their knee problems and make improvements that the person can utilize in their selected activity? Yeah maybe it feels better on their knee at the time but... I just don't see any carryover.
Have a great weekend!