In the world of strength & conditioning a lot of the S&C coaches out there uses the phrase "rate of force development" or for this text "RFD", because this is allegedly most important component that has to be improved in sport performance. Firstly let’s start with what is RFD?
It has been defined as the rate of rise of contractile force at the beginning of a muscle action (Aagaard et al., 2002). It has also been said that RFD is shown in the short and long components of the stretch shortening cycle (SSC) in other words in sprinting / jumping / bounding and plyometrics. The short components happens in 100-250 milliseconds of muscle activation and the long component is over 250 milliseconds (Schmidtbleicher 1992)
So basically this relates to the amount of force that can be produced in the shortest possible time or the ability to produce high levels of force in short times.
Esteemed sport scientist and athletics coach Vladimir Zatsiorski he uses 3 calculations to determine RFD:
1. Index of explosive strength (IES)
= Peak Force / Time to peak force
2. Reactivity coefficient (RC) (Jumping or Take off ability)
= Peak force / (Time to peak force X Weight of athlete or implement/object)
3. Gradient / Force gradient (Starting power)
= 1/2 of peak force / Time to peak force MINUS the time it took to get to 1/2 of peak force.
In other word the calculations above gives us 3 things that makes up RFD namely
1. Peak force
2. Jumping and take of reactive ability
3. Starting power
All three has to be HIGH to theoretically get a high RFD. While RFD is important the results of the program or intervention will be determined by one of my favourite sayings: "To teach Johnny Latin, you need to know Johnny and you need to know Latin."
In other words I 1st need to know my athlete (physical capabilities and training history) and the sport or/and environment he/she competes in.
Looking at athletics or sports similar to athletics sprints, jumps and throws then perhaps RFD is the most important component when looking ONLY at the end product, but if your athlete does not have sufficient maximum strength because he or she is a beginner or correct inter-muscular co-ordination or poor mechanics then perhaps you can still focus on the foundation of moving with proper mechanics and building basic strength which should at that specific athletes level give improvements in RFD without having exercises that specifically try increase RFD.
Then you get team sports that impose various demands on the athlete of which RFD is ONLY ONE! If we take an American football vs. Rugby Union Tackle both can happen at high speed and with a big collision... The difference is that the American football hit ends basically when the collision is done, whereas the Rugby Union's tackle carries on indefinitely after the collision where the players fight push pull and wrestle for possession of the ball and other players also hit into them to join the “fight”. Once the players hit each other in Rugby other components come into play like maximum strength, technique, flexibility and body position etc. The comparison and analysis can be done with various other sports like Soccer Netball, field & ice Hockey.
Some sports need other components more like accuracy and concentration like cricket for example yes, RFD is important but is all for nothing without bowling accurately or hitting the ball with correct timing or having enough flexibility to execute sport specific techniques.
I think what is important to know is that RFD is just ONE component and sometimes it doesn’t help you try work on RFD specifically in the weight room because most of the time the sport movements itself is MUCH faster than what you can do in the weight room. Rather ensure the athletes have the foundation to potentially achieve optimal RFD and improve other physical components that is specific to their OUTCOME!
Sometimes if the exercises become too fancy and complicated you lose the efficiency of it. For example your athletes can push “100 billion gigabytes” of force on the Flurbegoogle machine but they can’t stop an opponent that is smaller than them in a head on collision. ( FYI force is not measured in gigabytes and I am not aware of a Flurbegoogle exercise machine I just want to illustrate how some Strength coaches try and sound clever by using useless jargon ;-)
In other words they can perhaps produce alot of force in the fancy pants program you are doing but they cannot apply it on the sports field.
In closing always ask questions that can bring you to better performance! Like will the $100’000’000 flurbegoogle machine translate to worthwhile results?
In : Strength
Tags: rfd "rate of force development" performance
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