For the past few years, speed training has become the new rave within the fitness industry; neatly fitting into the periodization model for supposed optimum conditioning.  Whether you’re talking about speed training explosive training, the concept is to moving or accelerating the resistance as quickly as possible.  Questions remaining include: 1) Will moving quickly develop quicker muscles? 2) Will moving quickly produce better results, i.e., ability to mover faster, than moving slowly? 3) Is it safe to move quickly?

Quicker Muscles
Consider that some authorities whom promote speed training also contend slow movement (e.g., 3-4 second concentric or slower) makes you slow, or at least will not improve speed.  There are several problems with this reasoning, some of which were addressed previously but deserve reiteration. 

Primarily, it is force that enables you to move faster.  Simply try to move faster without exerting greater force.  If you discover a method to the contrary, share it with the automobile industry and become wealthy.  Now consider elementary physics – that moving a resistance from point A to B (distance) requires force and a magnitude of time to complete the lift.  Add it all together and you have the prescription for power, which is force x distance ÷ time, or the rate of doing work.  

By increasing force (i.e., muscle strength), and not speed, you become more powerful and faster.  Speed is merely the result of force. As Isaac Asimov stated in his book, Understanding Physics, “a force is that which can impose a change of velocity on a material body; (a force is) that which imposes a change in speed of a body, or its direction of motion, or both; without a continuous force, there would be no continuous acceleration.” 

It is a fact that a stronger athlete (relative to his or her own previous ability) is a more powerful and faster athlete, but within reason and limitations.  Those who compete with light implements, i.e., tennis or Ping-Pong players, increase speed of their swing and delivery by skill practicing, mental focus, and drills to increase reaction time.  Exerting against a light implement such as a racquet, air resistance, and a ball cannot provide sufficient opposing force (Newton’s Third Law) to allow greater muscular force up to a certain limitation... no matter how strong you become.  Athletes who do require high speeds against low resistance are at the mercy of their reflexes or nervous reactions (factors that are genetically predetermined), as well as their volitional effort and focus.  Speed weight training will NOT help.

Next, consider the idea that regardless of how fast you move a resistance, it is nowhere near the potential speed that is possible.  For example, a rapidly moving barbell (e.g., 50+% of your 1RM) may travel at 200° per second – perhaps a bit faster.  However, a sprinter’s limbs, unobstructed by a resistance (excluding gravity, ground friction, and air), can move and accelerate several times faster. 

How can a slower speed, while using resistance, increase the speed capability of muscles that contract much faster and under 90ms – especially considering one ‘pro-speed’ argument is that moving slowly in weight training will not build speed and that you must move quickly?  If lighter resistance is more specific to increasing maximal speed, as so many coaches advocate, then why not train with air resistance for maximal speed development?  Conversely, if some resistance is necessary, it should be evident the importance of muscular overloading of the weight to build strength/force to then develop greater speed with the speed of movement during exercise being irrelevant.

Realize that the speed you demonstrate power is specific and dependent on the sporting activity or movement.  The speed of movement at which you build power, however, is unrelated and independent of the speed you demonstrate power.  If you play a particular sport requiring fast movement, you should attempt to move quickly when practicing the particular sporting skills, thus demonstrating power, but not when exercising to build power.

Better Results
If you consider the reasoning above, fast movement is not superior to slower movement in producing quick muscles, power or explosion.  Moreover, the faster you move, the greater the acceleration and momentum.  That means a quick blast out of the starting gates resulting in high forces at the commencement of movement.  What follows (if not injury) is muscular unloading for part of the range of motion as the resistance propels upward and until gravity slows the weight down.  How can muscular unloading be beneficial if the concept of strength training is to train (not relax) the muscles? 

Also, what mechanically transpires during fast movement that does NOT transpire during slow movement?  Speed proponents are unable to respond rationally, often substituting mystical terminology, gut hunches, beliefs, and hypotheses for fact.  Muscles contract –  period.  Whether you move quickly or slowly, their job is to generate or resist force (resisting force via contraction), regardless of speed.  And, as stated, it is force that produces speed and acceleration.

Safety
The faster you move the greater the risk of injury.  Moving a light weight explosively is just as dangerous as moving a 1RM slowly (although you  may be producing maximum force to move it as quickly as possible).  Speed proponents, at least, concur that there remains risk of injury during explosive movement. 

Exercise, however, should not increase any risk, but should increase functional ability to prevent injuries.  It is understandable that Olympic lifters and powerlifters run the risk due to high forces of lifting a 1RM, but that should not apply to the rest of the population.  Many professional athletes have injured themselves from high-speed training, and they are genetic superiors who can better sustain such rigors.  If they run the risk of injury, what does that indicate about the norm?

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Brian D. Johnston is the President of the International Association of Resistance Trainers (I.A.R.T.), providing certification and education resources for personal trainers, coaches, and athletes.  His website is www.ExerciseCertification.com, where you will find dozens of free articles on exercise and nutrition science, including several on proper coaching practices for athletes.  Don’t forget to visit the learning resources section and pick up a book or video.  We have plenty of excerpts from each volume so you can ‘test the waters’ before buying.