We all know that (within reason) getting throwers stronger should yield better throws. But does it always happen and is there a point at which more strength is not helpful?
Hammer throwers are some of the strongest athletes, photo by dirkhansen
***
What was the study?
The study features a name that will be familiar to many readers of this blog, the one and only Michael Hartman. It’s called Maximum Strength-Power-Performance Relationships in Collegiate Throwers, Michael H. Stone, Kim Sanborn, Harold S. O’Bryant, Michael Hartman, Margaret E. Stone, Chris Proulx, Barrymore Ward, and Joe Hruby, Journal of Strength and Conditioning Research, 2003.
Since Michael does read this blog, I had better be on my best behaviour!
***
What I’ve been thinking about recently
Warning: the following two points are related but largely not entirely relevant to this study. They are, however, related to other articles in this series and I have nowhere else obvious to write about them.
_
Sprinters may be better at jump squats because they are born that way
Firstly, I’ve been thinking a lot about a study I looked at two weeks ago, called strength and power characteristics of sprinters, Olympic lifters and powerlifters.
In the study, it appeared that sprinters and Olympic lifters had similar vertical jumps (but powerlifters were way behind), and that sprinters had better jump squats than either Olympic lifters or powerlifters with any percentage of their 1RM back squat. I was surprised at this and I still haven’t got my head around why it happened.
The most convincing explanation I came across was gracefully supplied in the comments. It was suggested that the tendency of the athletes to self-select for sports that they are good at may imply that athletes with genetically better jump squat ability tend to become sprinters.
Or, perhaps the normal training routine of the sprinters lends itself to being good at jump squats. Either way, we don’t progress very far in our knowledge as a result of the study, unfortunately.
_
Olympic lifting is a throwing event
Secondly, I have very much enjoyed Lyle McDonald’s exceptional Olympic Lifting series.
In that series, I was very struck by one thing he said. He said: “the single limiting factor in the Olympic Lifts is this: throwing the bar high enough. Because if you don’t have the bar height in the first place, none of the rest of it matters anyhow since you can’t get under it.”
Reading that, it suddenly hit me that Olympic lifting is a throwing sport, only with a really heavy implement. It therefore has more in common with hammer throwing or shot than it does with powerlifting.
Hence, while powerlifting is mostly about limit strength, Olympic lifting, like all throwing sports, will have a point at which more limit strength is irrelevant without increased rate of force development. Since the implement is heavier, the point will be further down the strength scale but it will exist nevertheless.
Eureka. Thank you Lyle.
***
The background to strength and power
Anyway, enough of my ramblings, let’s take a quick look at some basic concepts and issues before we get stuck into the study itself.
What is strength? Strength is the ability to produce force. The authors of this study (including the illustrious Michael Hartman) note that strength depends on a number of factors such as the type of contraction, rate of motor unit activation, and degree of activation.
What is power? Power is the product of force and velocity. Consequently, changes in force should affect changes in power production.
What are the main factors influencing power? The authors note that maximum strength is the basic quality affecting power output. However, they add that after a certain level of strength is achieved, rate of force development becomes more important.
What is this rate of force development? Rate of force development is the change in force divided by change in time. Forces do not come out of nowhere to accelerate objects but need to be developed from a standing start. The faster a given force is achieved, the larger the impulse, the faster the corresponding acceleration and therefore the further the object is thrown.
What influences rate of force development? The rate of force development is primarily a function of the rate of increase in muscle activation by the nervous system.
So is the relationship between strength and power linear? Well, no. While it seems that strength has the biggest effect on power, it is not the only factor. Rate of force development is also critical.
***
So what does the study set out to do?
The study studied a group of eleven college-level throwing athletes over an eight-week period as they trained. During the first four-week period, the athletes focused on maximum strength training. During the second four-week period, the athletes focused on power training. Prior to the eight week period, there was a six week period of strength-endurance training.
The study was intended to describe the relationships between:
- Peak force
- Peak rate of force development
- Peak power
- Throwing ability
The results were as follows:
Eight-week effect - Throughout the eight-week training period, the following key variables all increased: peak force (4.1%), peak rate of force development (19.6%), and peak power (21.8%).
At the same time, the snatch improved 5.9kg from 61.8kg to 67.7kg and the shot improved from 11.99m to 12.63m.
First four weeks - During the first four weeks, when maximum strength was being trained, greater increases were observed in both peak rate of force development (25.4%) and peak power (17.5%) but peak force only increased a small amount (0.5%).
At the same time, the snatch improved 3.7kg from 61.8kg to 65.5kg and the shot improved 26cm from 11.99m to 12.25m.
Second four weeks - During the second four weeks, when power was being trained, peak rate of force development actually decreased (-4.6%), while peak power only increased by 3.7%. On the other hand, peak force also increased by 3.7%.
At the same time, the snatch improved 2.2kg from 65.5kg to 67.7kg and the shot improved 28cm from 12.25m to 12.63m.
***
So what does it all mean?
The authors interpret the results of this study such that:
- Increasing strength increases power
- Increasing strength increases power at both light and heavy loads
So far, so normal. But if you’ve been reading carefully so far, I bet you have a burning question, right?
If you were paying attention earlier, you’ll have realised that the maximum strength four-week training period caused the increases in power and rate of force development but did not increase maximum strength.
WTF! It’s the wrong way around!
Conversely, their power four-week training period caused increases in maximum strength but did not significantly increase power and actually decreased rate of force development markedly. How very odd.
The authors were also puzzled by this and proposed some solutions to this interesting problem, as follows:
- The effect of previous training periods might have been delayed (fatigue masks fitness?)
- The strength-endurance period done previously might have dampened the maximum strength achieved in the first four-week period
- There might be a delay before either maximum strength or power characteristics can be fully utilised into sports performance (this is certainly seen in track)
- One training period might have potentiated the next and allowed it to create greater increases than it might otherwise have done if it had been run alone
- There were power movements in the first four-week period but there were fewer of them. These may have been sufficient to cause power increases during that period
If you think about it, though, it seems to me that none of these alone can fully account for the complete reversal of the training programme/effect observed. It looks like there might be a combination of factors going on.
For example:
Time lag - if there is a time lag, that explains the improvements in force in the second phase, where power was being trained, since force was being trained in phase one.
However, it doesn’t explain the improvements in the rate of force development that occurred during the strength training phase.
I was going to work through each of the explanations but it started hurting my head. I can’t see any logic here at all. I would love to see longer periods of pure strength training and pure power training with the same type of athletes to see what happened to the metrics over a longer time frame.
***
Practical applications
This is another one of those great studies that has an idiot’s guide at the end for how to implement the results in your own training. Brilliant.
The authors note that:
- Increasing maximum strength can increase power
- Increasing maximum strength can increase peak rate of force production
- Maximum strength, power, and specific sports performance variables do not appear to change at exactly the same rate
- Increases in strength may continue after the changes in power or sport performance become asymptotic
- The lack of direct correspondence between maximum strength gains and other performance variables might be associated with a lag time
- Caution should be exercised in completely depending on maximum strength gains to enhance power output or sport performance, especially among ad- vanced or elite athletes
- To maximize power and explosiveness, specialized programs that also specifically train power and speed are necessary
Most of that list will be familiar territory but I like the clear conclusion that increasing strength increases not only power (since power is the product of force and velocity) but also the key driver of velocity, rate of force development.
The hypotheses that I am really curious about are:
- whether power training can increase maximum strength as fast as pure strength training
- what happens during longer periods of pure strength or power training
***
I hope this hasn’t been too laborious to wade through. It is a rare study that I have found that actually follows genuine athletes through genuine programmes, rather than some odd smith-machine type exercise using college students unused to exercise. So, even if the data is a little confusing, I find it more relevant than many others I have read.
