Mechanical Specificity: Triangulating On The Target I

The 3-headed “needs analysis” monster is a necessary first step in planning training. Here’s how to get an accurate fix on your performance target — starting with its mechanical demands — along with some practical take-aways.

“These natural laws have consistent, predictable consequences.
They exist whether or not we recognize them.
And they exert their effects on us without our consent or awareness.”
— Hyrum Smith

The longer I’m involved in the sports performance profession, the more I appreciate the elementary concepts I learned as a kid. That may sound strange coming from someone who explores advanced topics and takes pride in being scientific, but it’s true. In fact, the more scientifically you approach the field, the more frequently you’ll find yourself confronting the basics — and the more you’ll realize that advanced concepts are really just fundamentally sound. In my experience, this is one of the great insights of our profession.

Here’s how simple some of the most advanced issues can be:

• If you want to be sure your training program is “sport specific” and avoid the simulation trap, triangulate on the target. That’s orienteering 101, straight out of the boy scout manual.

• In order to task your athletes with the right things at the right times and steer them toward that target, think like an educator. Teach developmentally-appropriate content, and get your students fluent in “sport generic” prerequisites first.

• The secret of periodization is actually pretty anticlimactic: build your program on an educational model. Curriculum design is the name of the game.

The reason for illustrating my point with these examples is that, together, they summarize the whole planning process. There are 3 essential steps involved in preparing any sound strategy, including a training program:

1. Zero in on the performance target. This gets into the issue of specificity.
2. Assess the situation. This must be done with regard to students’ developmental status.
3. Select tactics for achieving generic as well as specific goals and objectives. This gets into the issue of planned variation in means and methods, i.e. periodization.

Even if you’ve mastered steps #2 and #3, you can miss the target badly if you don’t get an accurate fix on it first. Veering off course even by just a little bit early on can get you into big trouble later. That’s a distinct problem because step #1 — analyzing task demands — is the dreary part of the process. Who wants to spend time on some mundane needs analysis when there’s coaching to do? Besides, we already know what’s specific and what isn’t, don’t we? Let’s get on with it and focus on the fun stuff.


Time Out
I won’t try to pull the everything-you-thought-you-knew-is-wrong schtick. But if you see where I’m going with this, you should be prepared to leave your comfort zone. Here’s why: even if you keep your baloney detector cranked up to maximum, you may find that a half-truth or two has slipped through your defenses. I know, that’s not supposed to happen. But give the carnival barkers of the world credit. There’s no denying how some of them influence pop culture. Their sales pitches are cute and their koolaid is tasty, and they sure are persistent. Mostly they’re counting on the fact that people avoid critical thinking like a root canal.

So at the risk of being uncomfortable for a moment, let’s rethink this specificity thing and see what’s what. Heck, it might just validate that everything you thought you knew is right!


Checking Basic Assumptions
If you accept what I wrote in June — that specificity has a few nuances to it, and the sports training scene has a bad case of simulation — then the smartest thing you can do is back up occasionally and reconsider fundamental ideas. That’s especially true when the idea in question gets hackneyed and misinterpreted the way specificity does.

To summarize: we can’t rely on outward appearances when analyzing task demands. We need objective criteria. Specificity exists in several dimensions, providing us with a framework for those criteria: mechanics, energetics and coordination. Think of these as three perspectives you’re using to get a fix on a 3-D target. It’s important not to rely on any single vantage point because certain things won’t be visible from there. To make sure we don’t miss something, we need to triangulate on our target — just like a good navigator or outdoorsman does.

That’s all fine and good as a paradigm, but as practitioners we need actionable ideas. So let’s take a closer look at specificity from each perspective. We’ll start with mechanics, which will be the focus of the remainder of this article. I’ll tackle energetics and coordination in subsequent posts.

Buckle up your headgear. The basic concepts below may be older than dirt, but some of the take-away messages challenge the conventional wisdom.


Specificity³: Mechanics
In high school, I thought physics was the science of memorizing lots of formulas and laws without understanding what they meant. I was just trying to pass the tests. Years later, I discovered what those laws really mean.

They mean everything.

If you want to understand how things move and work — even if you’re a coach, and those things are bodies or barbells — physics is where it’s at. I don’t mean the subatomic or quantum stuff. I’m talking about foundational mechanical concepts: power, impulse and force. A decade after my first hack at these three laws, while trying to get my head around biomechanics (physiology was my strong suit), they kept resurfacing over and over. I never got too excited about lever systems or movement planes; but every granular, real-world discussion of mechanics I could find dealt with power, impulse and force. Now that was fascinating because it brought everything together.

There’s good reason for this. Functional strength is expressed in terms of velocity (power), rate or time of application (impulse), and acceleration (force). Indeed, the universal job description for athletes might read: “If you expect to win, you must apply power/impulse/force more skillfully than your opponent. It’s trainable. Get to work.” Think about it. It’s true in sports that involve biking, jumping, lifting, running, rowing, skating, skiing, striking, swimming, throwing — and any others I’m forgetting where moving faster than the other player matters.

So I kept revisiting these three concepts. And looking at the corresponding diagrams. And digesting the conventional (as well as not-so-conventional) belief systems. Some of those beliefs made sense; others didn’t. Some interpretations seemed to be on the right track. Some, like the peak power worshipers, combined elements of truth with nonsense. Others were completely asinine, like the HIT jedis’ endless assault on reason. Not to digress, but there’s an important lesson here: Valid concepts can be misinterpreted, either intentionally or unintentionally; and the resulting half-truths are very dangerous because those kernels of truth can seduce people. Actionable ideas require valid principles as well as sound interpretations. I posted a few musings on this issue in September.

Maybe it was just a matter of digesting power, impulse and force concepts enough times, but I finally picked up on some take-away messages that had been jumping out at me all along. I just needed to see them. So here they are, compiled into a short course on the science and practice of mechanical specificity. Yes, we’re (briefly) going back to school now. No, this isn’t the last word on the subject. I’ll try to spell out the actionable ideas without insulting anyone’s intelligence too badly.


Power. As best as I can tell, there are at least 5 take-home messages about the F-V curve that too few folks are taking home:

The force-velocity relationship in skeletal muscle [dashed red line], and resulting power production/absorption [solid blue line], in concentric and eccentric actions. The greatest forces occur during explosive eccentric (lengthening) actions. Depending on the movement, peak power [Pm] is usually produced at 30-50% of maximum force [Fm] and velocity [Vm]. Redrawn from: Newton R.U., Kraemer W.J. Strength & Conditioning 16(5): 20-31, 1994. Adapted from: Faulkner J.A., Claflin D.R., McCully K.K. In: Human Muscle Power, N.L. Jones, N. McCartney & A.J. McComas (Editors). Champaign IL: Human Kinetics, 1986; pp. 81-94.

• There is a reciprocal relationship between F and V. On one hand, motion (as measured with metrics like velocity and acceleration) only occurs as a result of force. On the other, our ability to apply force is velocity-dependent.

• The eccentric side of the F-V curve is not a mirror image of the concentric side. There’s an inverse relationship between concentric (shortening) F and V; whereas eccentric (lengthening) F tends to increase with V. People who are not prepared for the extreme F and power absorbed during explosive braking actions are at serious risk of injury and/or underperformance.

• Think of the F-V curve as an illustration of the stretch-shortening cycle. When we move, we regularly traverse from the lower/right side (eccentric action) to the upper/left side (concentric action). There aren’t many movements that exist at a specific point on the curve. Most involve a range of F, V and power inputs/outputs. Furthermore, this occurs in real time — usually tenths of a second, even during nonballistic movements. More about that in a moment.

• It’s true that peak concentric power occurs at intermediate F or V, but we don’t land on top of the mountain by falling there. We have to climb the power curve, which ties in with the previous point. So whether we’re performing a “heavy resistance” movement or “explosive” movement, we should think of velocity specificity as the final/top speed achieved — not as the only V or power that matters, or the only point on the curve to train for. This is why power is important across the entire curve, not just in the peak zone.

• Training at different zones on the curve tends to amplify the overall effect. Think of various potentiation methods (complexes, combinations, wave loads etc) in terms of how they prompt us to apply effort in different zones. This is why “nonspecific” movements still serve a valuable role even for advanced athletes — another reason to strike a balance between generic and specific training methods without going overboard in either direction. One tactic can set up another.

Impulse. Real-world movements have time constraints where F application is necessarily measured in tenths of a second. This is true for ballistic, high-powered activities like running and jumping as well as nonballistic, low-powered activities like walking. Thus, the F-T curve gives us another useful window on movement mechanics:

Force as a function of time, indicating maximum strength, rate of force development [RFD], and force at 0.2 second for untrained [solid blue line], heavy-resistance trained [dashed red line], and explosive-ballistic trained [dotted black line] subjects. Impulse is the change in momentum resulting from a force, measured as the product of force and time (represented by the area under each curve), and is increased by improving RFD. When performing functional movements, force is typically applied very briefly, i.e. often 0.1 – 0.2 second, whereas absolute maximum force development may require 0.6 – 0.8 second. Redrawn from: Newton R.U., Kraemer W.J. Strength & Conditioning 16(5): 20-31, 1994. Adapted from data from: Häkkinen K., Komi P.V. Scandinavian Journal of Sports Science 7(2): 55-64 & 65-76, 1985.

• Regardless of how strong you are, it takes time to reach whatever peak level of F you’re capable of applying. While this varies with the task being performed, fast-twitchy athletes can develop peak F toward the lower end of the range (~0.6 sec); whereas slow-twitchy athletes develop peak F toward the higher end (~0.8 sec). This is trainable.
  

• Many functional tasks don’t allow us the luxury of time; hence the importance of RFD. An elite sprinter (running @ 12 m/sec) must execute ~5 strides/sec, with ground contact times of 0.1 sec or less; an elite marathoner (5-6 m/sec) must execute ~2.5 strides/sec, with ground contact times of 0.2 sec or less, and so on. We do not have the option of applying F over longer time intervals in order to produce the required impulse — a fact that applies not only to ballistic locomotor tasks like running, but many other activities as well. Brief application of F is the rule rather than the exception in functional movements.
  

• For the most part, what you train for is what you get; although a combination of methods tends to amplify their overall effect. “Heavy resistance” movements tend to move the F-T curve up, while “explosive” movements tend to move it to the left. The best of both worlds is to use one method to potentiate the effects of another. Once again, “nonspecific” movements can serve a valuable role even for advanced athletes.

Force. The great thing about F=m•a is that we don’t need a graph to illustrate it. A cartoon will do. You have to love that now that we’ve already sprained your brain:

• Once the mass is established, by definition, maximum F is achieved by maximally accelerating it. Hence, movement ROM can be considered an acceleration path. While F is load-dependent, the intent to move explosively — i.e. maximally accelerating the resistance with sound technique, even if it’s too heavy to move rapidly — is equally important. Full volitional effort yields the greatest neuromuscular activation and adaptive response.

• During ballistic movements, accelerate with good form through the full ROM and launch the mass at maximal V. This applies to virtually any activity involving a projectile — e.g. running, jumping, throwing, kicking etc. Note that Olympic weightlifting movements are unique examples of semi-ballistic actions: the mass is accelerated through the initial ROM; but rather than release the bar, the athlete maintains his/her grip and catches it across the shoulders (e.g. clean) or at arms’ length overhead (e.g. jerk, snatch).
  

• During nonballistic movements like the squat or deadlift, accelerate with good form through the sticking region (typically the first 1/3 - 1/2 of ROM) and then decelerate as you approach full extension (e.g. the last 1/3 - 1/2). In this sense, “heavy resistance” movements can be performed “explosively”. Using the squat as an example: sit at a controlled speed into an optimal position (don’t free fall into the descent); accelerate out of the hole and through the sticking point as powerfully as possible; and throttle down at the top of each rep so the bar doesn’t jump off your shoulders. Sound risky? Remember gravity will decelerate the bar as you back off your effort toward the top of the ascent. Plus we’re talking about at least moderately heavy resistance that isn’t easy to move rapidly even when attempting to do so (gravity is always trying to decelerate it). If the bar is still moving upward by virtue of momentum at the top of the ROM, consider two options: you may be accelerating beyond the sticking point, and should adjust your effort during the latter part of the rep; or the resistance is so light that you would do better to perform a ballistic movement with equipment designed to be launched explosively.
  

• Don’t confuse this method with “speed reps” where light weight is accelerated through the entire ROM without releasing it. Such movements are futile because more effort is spent decelerating the weight for self-protection than accelerating it for beneficial F generation. It’s true that eccentric muscle actions are part of normal movement, and that negative work plays a useful role in strength development when prudently applied. However, such lengthening muscle actions are best performed as preparatory countermovements (from a flexed position) rather than terminal braking motions (at full extension).

• In addition to selecting a movement technique that enables the athlete to maximize F application, we must also choose appropriate work protocols. In practice, this has several implications: conduct strength training after appropriate priming activity in conditions of minimal fatigue; structure training sessions around brief work bouts and frequent recovery periods; where feasible, distribute daily sessions into modules separated by recovery breaks; and further subdivide workloads into brief clusters separated by rest-pauses. The rationale: fatigue is a progressive process that begins at the onset of work and affects task execution well before failure occurs. It’s a normal result of intense activity, but must be managed because it interferes with skill acquisition and performance.
  

That Wasn’t So Bad...Or Was It?
Taken one at a time, the typical response to these points is “thanks, I already knew that.” Unfortunately, many people should qualify this with “...but I still disregard it regularly.” Fundamentals are funny things — essential yet unexciting, and profound when taken together. Even though overlooking them is a costly mistake, it sure seems to be a great way to become popular!

So there it is, my deranged take on the mechanical specificity side of our triangulation scheme. All we really did was take a closer look at the forces, or kinetics, involved in locomotor activities; and then infer some training guidelines. That’s a perspective we otherwise wouldn’t get by looking just at movement patterns, or kinematics. If you’re familiar with the dynamic correspondence paradigm (Verkhoshansky 1977, 2006), you’ll notice we’ve been leaning on that pretty hard. According to this concept, training tasks should be specific to the target activity in terms of:

• Rate and time of peak F production (impulse) and the range of V at which it is applied
• Dynamics of effort (power)
• Amplitude and direction of movement
• Accentuated region of force application
• Regime of muscular work

Finally, this whole triangulation concept is just a revised approach to needs analysis, the first step in exercise prescription (Kraemer 1983). Dr K originally proposed a two-pronged (mechanical and energetic) analysis of the target activity. We’re simply adding a third prong (coordination) and updating the criteria used in each. Next up: energetics and coordination.

Acknowledgment

Thanks to John Goodwin.

Resources

1. Fleck S.J. & Kraemer W.J. Designing Resistance Training Programs (3rd Edition). Champaign IL: Human Kinetics, 2003.
2. Kraemer W.J. Exercise prescription in resistance training: a needs analysis. NSCA Journal 5(1): 64-65, 1983.
3. Plisk S.S. Speed, agility, and speed-endurance development. In: T.R. Baechle & R.W. Earle (Editors), Essentials of Strength Training & Conditioning (3rd Edition). Champaign IL: Human Kinetics, 2008; pp. 457-485.
4. Stone M.H., Stone M.E. & Sands W.A. Principles & Practice of Resistance Training. Champaign IL: Human Kinetics, 2007.
5. Verkhoshansky Y.V. Fundamentals of Special Strength-Training in Sport. Moscow: Fizkultura i Spovt, 1977 [Livonia MI: Sportivny, 1986; translated by A. Charniga Jr].
6. Verkhoshansky Y.V. Special Strength Training. Muskegon MI: Ultimate Athlete Concepts, 2006.
7. Zatsiorsky V.M. & Kraemer W.J. Science & Practice of Strength Training (2nd Edition). Champaign IL: Human Kinetics, 2006.

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