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Max Power vs. Joint Angle
Posted: Thu Oct 02, 2008 1:37 pm
Here's my question, I am curious as to the relationship between Max POWER and joint angle. More so, the relationship of Max power output joint angle and antagonist muscle groups.
For example, the knee joint - (Flexion and Extension). I would like to see a chart representing the max power generated throughout the entire range of motion. I would like to compare and contrast the concentric flexion of the hamstrings, vs. The concentric Extension of the quads.
Ideally I would like to see a study done of elite well balanced athletes. With all joints represented.
Any help and insight would be great.
Posted: Thu Oct 02, 2008 4:32 pm
Would you be the Blue Running man from the top of ExRx? Several of have worried about you at times, running endlessly but not seeming to get anywhere. It's good to know that you are at least able to think heavy thoughts while you are running.
I'm not sure that this is the full answer you are seeking (Kenny would probably be able to tell you a lot more), but I believe that the relative power at varying angles depends on the mechanics of the joint more than on the level of training of the person. In other words, the strength at my knee at 90 deb compared to 60 or 120 deg is likely to be a similar ratio as it would be for a stronger lifter, although the values themselves would be smaller.
I suspect that the relationship depends on such things as where the muscle(s) insert on the bones (distance from the pivot point of the joint) and the length of the bone, and the range of the joint. I would think that it's fairly simple lever mechanics for the elbow and the knee, but more complicated for such joints as the hip, where several different muscles make different contributions at different angles. In fact, I'm guessing that the power of the hip is more consistent through it's range than the elbow, which I'd guess has significantly higher output near 90 degress.
I know that you didn't really want just some guy to get on and speculate, but I thought it was an interesting question to think about.
Posted: Thu Oct 02, 2008 6:22 pm
thanks for the input.
I totally agree with you regarding the mechanics of the joint as a factor. That's why I'm so interested in this topic. The ankle is the joint of my highest concern. The reason I mentioned athletes is because I'm looking for ideal conditions.
I found a Flexor Torque x Elbow Joint angle chart in a kinesiology text, you are correct, in that the elbow seems the strongest at 90 degrees, during flexion.
Although this still doesn't answer my question as the text lack as similar chart for elbow extension.
Posted: Thu Oct 02, 2008 7:16 pm
If you think about how elbow extension works, it's like a strap being pulled over a pulley. There is no reason for it to be stronger or weaker at any point. However, if you look at a pressing motion near lockout you see that the angle at the elbow changes more relative to the distance of the press, therefore in a press, the triceps appears stronger at lockout. It's the same reason you're stronger at the top of a squat than at the bottom.
Posted: Thu Oct 02, 2008 7:51 pm
stuward wrote:If you think about how elbow extension works, it's like a strap being pulled over a pulley. There is no reason for it to be stronger or weaker at any point. However, if you look at a pressing motion near lockout you see that the angle at the elbow changes more relative to the distance of the press, therefore in a press, the triceps appears stronger at lockout. It's the same reason you're stronger at the top of a squat than at the bottom.
This is what I'm trying to confirm graphically. Is ideal muscle balance, truly an equal power balance between antagonist and protagonist muscle groups, throughout ROM?
Continuing with the elbow. Is it ideal for the elbow to be able to generate equal power in both directions? What about the hip, shoulder, knee and ankle?
Surely with the ankle, it is hardly likely for someone to be able to generate similar power, dorsiflexion vs. plantar flexion. The Second class lever system of the ankle gives an advantage to plantar flexion.
Exercises like the Row vs. Bench Press. Should you really be able to pull equal amount of weight as you push? Leg Extension vs. Leg Curl?
Assuming, the goal is to establish a 1:1 ratio between push:pull power, at what ratio, does it become an injury risk?
Posted: Thu Oct 02, 2008 8:07 pm
There are suggested ratios but there really is no reason for exactly 1-1 in all cases.
Posted: Thu Oct 02, 2008 8:50 pm
I have looked online for some credeble information regarding Strength Ratio's on the net, to no avail. If some one could find some information about this, that would be great.
I've seen some sites say, that sprint athletes should have a ham:quad ratio of 1:.8, meaning that the hams are about 20% stronger than their quads. The same site said that the average person has a ratio of 1:.6.
Other sites I've gone to have said 1:2, meaning that the muscles responsible for knee extension should be twice as strong as the muscles responsible for knee flexion.
What about hip abduction/adduction?
At what point do strength/power imbalanced become an injury risk? We've all see the people at the gyms with the 4 years old program, that focuses on Bench and Bi's? We all see the negative effect these types of programs have on the individuals posture. I'm sure injures can occur from negligence like this, but to what extend?
Posted: Thu Oct 02, 2008 9:11 pm
stuward wrote:There are suggested ratios but there really is no reason for exactly 1-1 in all cases.
Anyone with a physics background could hopefully help answer this one.
When building a machine, with hydraulics about moveable joint. It's it important that the machine is perfectly balanced, in order to reduce prolonged wear and tear? Any imbalance would reduce the life expectancy and reliability of the machine.
Maybe that's not the case, What's most important is that the joint itself, remains in the ideal orientation. Mechanics responsible for keeping the joint in it's ideal orientation, need to be strong enough to withstand the torque forces created by the hydraulics.
If this is the case, then the power ratio between protagonist:antagonist, is of little relevance towards the health or stability of the joint. It's the ligament strength that needs to complementary to the power output of the muscle group.
Now I'm really confused.
Posted: Fri Oct 03, 2008 3:50 am
Cant help but think that this all revolves around evolution, the human example of joint/Flexion and Extension and muscle balances are far from perfect.
Enginnered examples would be better for perfection, depending on the purpose/goal.
Posted: Fri Oct 03, 2008 8:59 am
Blue Running Man wrote:...I've seen some sites say, that sprint athletes should have a ham:quad ratio of 1:.8, meaning that the hams are about 20% stronger than their quads. The same site said that the average person has a ratio of 1:.6.
Other sites I've gone to have said 1:2, meaning that the muscles responsible for knee extension should be twice as strong as the muscles responsible for knee flexion....
A ratio of 1:.8 would mean that the quads are slightly stronger than the hams. This is traditionally measured as leg ext vs leg curl. Leverages may play a factor in these exercises.
Dr. Squat says that for power lifters, hamstrings need to be much stronger than quads. It's common for body builders to have much stronger quads than hams do to the mirror effect, they don't train what they can't see in the mirror. So what it comes down to, the ratio depends on your sport.
There have been several good authors posting ion T-nation about ratios. I don't have access to T-Nation at work so I can't search. To much soft-porn on that site. Later on I'll post some articles I've seen on the issue.
Posted: Sun Oct 05, 2008 1:49 pm
I wouldn't mind checking out those T nation articles. I'll look for them myself too.
Basically what I'm hearing is that for most joints it's best to have a ratio around 1:1. Which makes sense.
My primary concern for this discussion is the ankle. Walking around all day, sprinting, calf raises, etc, these activities build up strong plantar flexors while our dorsiflexors are often forgotten about.
-What is the advantage/disadvantages of training dorsiflexion?
- How does this type of training affect sprint speed?