The Force-Velocity Curve
Periodization is an important topic in the strength and conditioning world. Put periodization in Google and you get 940,000 results. This is great if you're a sports science geek, but it's pretty overwhelming to the average athlete or weekend warrior who wants to get an advantage over his competition by using periodization. Yes, I hate to say it, but periodization has become pretty damn complicated. Is it a ploy by those pesky Russians to confuse us with all these advanced models? Conjugate periodization, block, linear, undulating, and many more have led to some great debates over the years, but they have also led to paralysis by analysis.
Turner (2011), in his review of the science and practice of periodization, describes periodization simply as “an optimal strategy for organizing S&C programs.” I believe that if people understand the force-velocity curve and base their training upon it, it is the simplest way to organize their programs optimally.
The force-velocity curve has an x and y axis. The y axis is the horizontal axis that denotes velocity, and the x axis is the vertical axis that denotes force. The curve itself is hyperbolic and shows an inverse relationship between force and velocity (e.g. the heavier the weight you lift (force), the slower you lift it (velocity); conversely, the lighter a weight, the faster you lift it). So different types of training occur on different parts of the force-velocity curve (figure 1). As you go from high force, low velocity to low force, high velocity, you go from max strength work to strength-speed to power to speed-strength to speed.
So how does this help athletes? Well, it is agreed that a desired effect of training is to shift the force-velocity curve to the right (Zatsiorsky 2006) because in sport, speed kills. As you should know, the problem is that adaptations to training are specific in nature. Figure 2 shows what happens to the force velocity-curve after strength training (blue line) and speed training (green line). In advanced athletes, if you train at one end of the force velocity curve, you will improve that part of the curve, but the other will decrease.
So what can we do? Train all the way along the force-velocity curve. The problem is your body can only adapt to so much. If you train all strength qualities at the same time, you won’t adapt optimally. This brings us back to periodization. One principle of periodization is to move from general training to more specific training (apologies to powerlifters). Strength is just general preparation whereas power and speed are more specific. So your periodization plan should travel from left to right down the force-velocity curve (figure 3).
I believe that everyone should train every part of the force-velocity curve, but how long they spend at each training stage depends on four things.
1. Training age
This is easy to understand. A beginner will need to spend more time improving max strength than an experienced athlete. Max strength is highly correlated to power and explosive measures (Peterson 2006), and improvements in max strength for a beginner can also improve speed. As the beginner becomes more highly trained, he will have to emphasize the higher velocity/sport specific speed training, but he will still have to train max strength to maintain it and increase power potential.
Different sports require different strength/speed qualities. For instance, a football player will require more strength work than a tennis player, but that still doesn’t mean that a tennis player shouldn’t improve his/her maximum strength. Part of the strength and conditioning coach’s job is to identify the requirements of his athlete’s sport through a needs analysis and then program accordingly.
Even in the same sports, different positions require different training. In rugby, a prop will require more max strength work than a winger. In football, a running back will require more speed training than a lineman.
4. Time of year/season
Earlier in the preparatory period, a stronger emphasis should be on max strength. As the season continues, a more specific approach should be taken and a greater emphasis placed on speed. Again, that isn't to say that you shouldn’t train all parts of the force-velocity curve, but I like to think of it as this—if your programming takes you from one end of the force-velocity curve to the other (from left to right) three times in a season, the whole block will become more specific each time. That is to say, you don’t perform the same max strength block three times at the start of each phase. You might spend less time on max strength each time or just perform a more advanced version each time.
I hope my point was clear—all athletes should train along the force-velocity curve. How long the athlete spends at each stage will depend on training age, sport, position, and time of year. Through a needs analysis and testing, it is up to the strength and conditioning coach to ascertain when it's appropriate to shift the entire force-velocity curve to the right.
- Peterson M, Alvar B, Rhea M (2006) The Contribution of Maximal Force Production to Explosive Movement Among Young Collegiate Athletes. Journal of Strength and Conditioning Research 20(4):867–73.
- Turner A (2011) The science and practice of periodization: A brief review. Strength and Conditioning Journal 33(1):34–46.
- Zatsiorsky V, Kraemer J (2006) Science and Practice of Strength Training. Champaign, Illinois: Human Kinetics.
If you take a look at position vs. time curves, you will find, I suspect, that the vertical axis is not - in fact - always the y-axis.
If anyone can correct me I'll be interested to hear your view :)