The Four Types Of Resistance Technology

Hi everybody, it has been a long time since I posted and I wanted to put up something fitness related.  This is an essay I wrote about the four types of resistance machines/technology that is out there.  It may not be interesting to some of you, but those of you who are into exercise science and fitness gadgets and gizmos, may find some interesting ideas and perspectives.  I hope you enjoy.

photo source: http://images.sciencedaily.com/2008/02/080205121740-large.jpg

The four technologies of training equipment are constant resistance devices, variable resistance devices, accommodating resistance devices, and static resistance devices.  Each one has different uses and has pros and cons depending on the user and purpose.  Constant resistance devices are things like free weights or pulley machines where the wheel is round so it gives even resistance.  One of the disadvantages of this type of equipment is that it does not correct for differences if biomechanical leverage changes.  Such as, in a squat with a barbell, the weight of the bar stays the same throughout the lift.  However, the squat will be much harder at the bottom due to reduced leverage and much easier at the top of the motion.  So at the top of the squat, we are losing some of the benefit of the exercise.  This is also an advantage, as it has been shown that this is how our muscles evolved to work and is a natural type of stress to the body that helps us develop better stabilization strength, and power as well (Hatfield, p. 199).

For general population training this will improve a client’s joint integrity through training the stabilizer muscles and also teach them how to move objects in real life better than machines.  Also for everyday people, this type of resistance training has a disadvantage.  For deconditioned people or first time exercisers this may be dangerous even with light loads.  They may have old injuries or just be so inflexible and immobile that the leverage disadvantage becomes too much when trying certain exercises with a full range of motion.  They also may not have the core or stabilizer strength to do the exercise safely.  In these cases, machine exercises may be a better option to start training.  For sports training the same advantages of these tools apply, athletes will encounter similar resistance to what they will find in real life on the field.  This is a plus.  A disadvantage is that these exercises may lack sport specificity where other tools may be better for some training techniques.  Such as using resistance bands to train a martial artists kick.  For bodybuilding and mass gaining constant resistance technology can be very effective.  This type of exercise can engage a lot of muscle mass at one time due to stabilizer recruitment and help to elicit a larger hormonal response and therefore muscle growth.  For some advanced bodybuilders this type of training tool may not be enough.  Some may require more advanced techniques such as fixing chains to a barbell and doing bench presses (variable resistance)  (Hatfield, p. 199-206).

The second technology of training equipment is variable resistance devices.  This can include offset cam machines that change resistance through the range of motion.  Some are made so they roughly follow the leverage curve for the movement so it provides more resistance as the range of motion becomes more favorable.  Dynamic variable resistance technology is another form, as well as spring loaded and resistance band machine.  For the general population an advantage of this type of training could be to serve as a break in the routine.  If a client is getting bored with doing dumbbell bicep curls, they could try some resistance band curls.  Another advantage is that it provides less resistance where the leverage is the worst.  So if a client is rehabbing a muscle, this could be useful.  They could work a full range of motion in the joint and be challenged at the top (say a bicep curl) but at the bottom where they are weaker and where the injury happened (say from hyper extension) the resistance is more accommodating (Hatfield, p.200-201). 

photo source: http://www.isokineticsinc.com/mm5/graphics/00000001/llpowerpunch2fs.jpg

In sports training these types of technologies could be used to train power for sport, such as the example I gave of a martial artist using a resistance band to train his kick.  This can be provided by variable resistance.  These tools can also be used to help someone through sticking points like using resistance bands to do reverse barbell bench press, or assisted pull-ups, to help the athlete build strength through the weaker ranges of a movement.  One disadvantage though is that these types of movements feel unnatural, nothing in the real world responds this way.  Essentially this type of training if not used correctly can confuse the motor unit signals to the brain and limit growth (if used to exclusion of other tools).  For bodybuilders and mass training, these technologies can be used to shock the muscles into new growth.  Using the overload principle, we know that to make a muscle grow you want to put maximum levels of stress on the muscle.  These technologies can help us do that.  Where they are limited is in their ability to develop the stabilization strength that you can with free weights.  Developing these important muscles will allow us to stay injury free and actually lift more weight and so maximize our muscle development.  Bottomline, variable resistance has its place in a well-rounded program but should not be used to the exclusion of free weights and other tools (Hatfield, p. 199-206).

“Accomodating resistance machinery is designed to allow you to exert maximum resistance throughout the full range of movement in each of your exercises” (Hatfield, p. 201).  This allows you to contract your muscle fully through the entire range of motion,at each point the “weight” is its heaviest.  This is done by controlling the speed at which you can move the machine.  An advantage of this for the general population is that when the speed is controlled by the machine, there is no ballistic movement.  This can be an important consideration for the untrained client who is just starting to exercise.  Ballistic training is important for everyone, but it is dangerous for the client who has been sedentary their whole life.  Keeping them safe by controlling speed can be useful in the early stages.  On the other hand, eventually you will want to introduce ballistic movement to everyone, because LIFE is ballistic!  If you fall or slip or have to sprint from danger, life is not a slow controlled movement (all the time).  So eventually the client will need more than accommodating resistance can offer (Hatfield, p. 201-203). 

photo source:  http://www.hawaiianshirtray.com/wp-content/uploads/2011/02/Air-Pressure-Accommodating-Resistance-Machine1.jpg

For sports training, this training tool has limited usefulness.  Sports movements tend to be ballistic, and indeed the nature of human movement is mostly ballistic, it is how our bodies are meant to work.  However this type of tool may have some limited use as a periodized training technique for pure strength athletes like power lifters who must generate maximal muscular contraction to move incredible amounts of weight.  On the other hand, some tools such as ergometers are electrically driven to provide a constant resistance, similar to what water provides.  So this could be useful for those athletes on crew to practice their sport specific conditioning.  For bodybuilding and muscle mass, again this comes down to stimulating the fibers maximally and in new and different ways.  In bodybuilding, you have to spend a long time to really get results.  This equals a lot of hours in the gym over a number of years, if you are going to be competitive.  So with that said, you are going to have to change things up from time to time to avoid boredom, injury, and burnout.  Changing your routine by incorporating different forms of resistance can not only give your mind a break, but your CNS as well.  Changing the way the muscles are stimulated can provide new growth and help you bust through a plateau to a new level of fitness (Hatfield, p. 199-206).

Lastly I will talk about static resistance devices.  This type of training is known as isometric training where the muscle is contracted and no movement occurs.  This would be like pushing up on a door jamb as hard as you can, you are contracting the muscle maximally but no movement happens.  You may not have heard of this type of isometric, maybe you are more familiar with the static pose type of isometric where you hold a pose against gravity for as long as you can.  This would be something like a plank, or a wall sit.  Maximal isometric contraction was popular in the 50’s and 60’s but died out shortly after.  It was found to be effective, but only for increasing strength at the joint angle trained.  This means that you do not receive increased strength through the full range of motion, which is the most practical type of strength (Hatfield, p.203). 

photo source:  http://www.ironmacfitness.com/wp-content/uploads/2013/02/alexander-zass-isometric-exercise.jpg

However, for general population use, isometric exercise can be an effective rehab tool because there is no joint movement which can be harmful in some cases.  But with isometrics no movement occurs and we can still strengthen the muscle.  For sports, this can be useful to train specific positions that are needed to be very strong.  Sport has a large element of predictability, which is good for training because we often know what positions need to be worked.  But, we also need full range strength in sport so we will need to incorporate other tools.  For bodybuilding and mass, isometrics will improve size very little.  However they can be very useful for training any sticking points in a lift such as the 90 degree point of a bench press.  Using isometrics can help you get past this when you are stuck at a certain weight.  This thereby aids your full range of motion training with free weights which WILL increase muscle size and strength.  (Hatfield, p. 199-206).

Source:

Hatfield, F. C.  (2011).  Fitness: The Complete Guide.  Carpinteria, CA: International Sports

Sciences Association.