T Nation

Force Development Question

I have read, skimmed over is a better way to say it, ar4ticles by a few coaches now who mention how a weighted bar is not a constant weight. I heard something like: a bar with 135 lbs on it requires 275 lbs of force to recover from the bottom position of the clean. Can anyone help me understanbd this. Are there any authors or formulas or sources of info that I should look into?

It makes sense that a falling bar will require more force to stop and reverse its path, I am just looking for a clear way to look at this and apply it to my training.

Thanks all.

[quote]ens-perfectum wrote:
I have read, skimmed over is a better way to say it, ar4ticles by a few coaches now who mention how a weighted bar is not a constant weight. I heard something like: a bar with 135 lbs on it requires 275 lbs of force to recover from the bottom position of the clean. Can anyone help me understanbd this. Are there any authors or formulas or sources of info that I should look into?

It makes sense that a falling bar will require more force to stop and reverse its path, I am just looking for a clear way to look at this and apply it to my training.

Thanks all.[/quote]

WTF?

Those numbers are way off base…with reasonable technique a person should be able to Cn whatever they front squat for 5. This is on the conservative side. With very good technique you should be able to CJ about your 3RM FS.

How does this apply to your training?

Whatever weight you can get under you should better be dam sure you can squat it for at least 2-3reps if you want to Cn it. If you are very good technically you can Cn about 10-20kg under your 1RM FS.

You don’t need any forumulas. Just work your technique so you can at least FS something for 5reps and with reasonable form you should be able to Clean and Jerk it.

Koing

That’s something that actually makes sense. Thank you.

The key to proper force production is a high midi-chlorian count.

[quote]TheJonty wrote:
The key to proper force production is a high midi-chlorian count.[/quote]

This is a wise one. Please ignore my comments and follow this Master.

Koing

The weight on the bar is always constant. The author is trying to explain the amount of force required to overcome the weight falling down and then accelerate it upwards. The 275lbs was given as an example of an amount of force used to overcome a 135lb weight. The force you apply has to be greater than 135lbs because you decelerate the bar and then accelerate it upwards. For simplicity, if you applied constant force, which results in constant acceleration applied to the weight, the time it takes to travel a certain distance can be calculated. You can use the equation below assuming constant force/acceleration:

(Force - Weight) = acceleration x mass = (2 x distance)/(time^2) x mass

Using the author’s example, lets say you applied a 275lb force (1223.3N) to overcome the 135lb weight (600.5N) over a length of 0.5m from the bottom position to the top position of a clean. We’re able to calculate exactly how long it takes if we assume constant acceleration:

(1223.3N - 600.5N) = (2 x 0.5m)/(time^2) x (61.23kg)
=> time = .3136 seconds

You can manipulate the equation however you like to solve for one variable. All the author is saying is that it requires more force than the actual weight to overcome it’s inertia or momentum and accelerate it. If you had a 135lb weight and picked it up slowly, you would apply less force and generate less power in comparison to if you picked it up as quickly as possible. It sounds like the underlying message the author is trying to get across is that you control how much force you generate and it is not equal to how much weight is on the bar. You could apply the concept of maximum power output to your training. I remember reading an article in the past couple years about some device that could be attached to a barbell to measure power output. That way, it doesn’t really matter how much weight is on the bar, only that you’re training for peak power.

Just did a quick search. It’s called the Tendo Unit:

http://www.tendosports.com/index.html

That article I read about training peak power was interesting. It discussed efficiency of training and reasons to stop the lift once your power output drops. I think it discussed recovery as well. I don’t think there were long term studies showing benefits though. I couldn’t find the article doing a quick search and I’m too lazy to spend anymore time on it lol.