Physiology

Keep Kids off of Machines!

Brian Grasso explains why we should limit the use of machine-based training with young athletes

Whenever I come into contact with a coach or trainer who preaches the virtues of machine-based strength training for young athletes, the same argument is typically offered - machines are safer for kids because they eliminate the dangerous aspects of traditional free weight training. This is simply a dogmatic mindset and not founded on any scientific or functional principal. It is a classic case of blaming the exercise or activity rather than the execution. In fact, having young athletes train on machines for strength development can actually lead to injuries and a whole host of other concerning factors.

Strength and stability

All sports are dynamic and require a great deal of systemic strength and stability to perform. More over, the strength/stability interplay needed to perform virtually any sporting activity is based on the body (or its parts) working as a unit; the way nature intended. By isolating certain muscles groups via machine-based training, you are eliminating the body's natural capacity to provide both mobility and stability in an interrelated manner. This can essentially limit a young athlete's ability to effectively produce force on the field of play while at the same time providing stability in other crucial areas of the body. By disturbing this innate mobility/stability balance, you are decreasing the ability of the body to protect itself during dynamic and unscripted movements experienced during a sporting event. Coaches and trainers who incorporate machine-based training into the routines of young athletes in order to promote weight room safety are in essence, increasing the risk of injury on the field of play. One of the primary goals of a sound strength and conditioning program is to prevent injuries during a sporting event or season - Coaches and trainers who insist on using machines for training purposes are then suggesting that trading sport safety for weight room safety is somehow a good deal.

Machine training

Here is a look at some of the finer points of machine training:

Seated vertical pressing machines place a great deal of stress on the lumbar spine - more so than standing vertical pressing exercises. In fact, many young athletes, in an attempt to press as much weight as possible, will actively hyperextend the lower lumbar in order to gain extra leverage.
Seated leg press machines do not afford backrests that equal the natural curvatures of the spine. More over, many young athletes tend to overload seated leg presses with extreme amounts of weight (likely because they perceive the exercise to be 'safe'). At increased loads during the eccentric or lowering phase of the movement, the lower lumbar will go through a forced flexion. This is a terribly unstable position for one's lower back to be in and could result in anything from minor to severe injury.
Hack squat machines can place a great deal of anterior shearing forces on the knee joint. As well, they tend to work primarily the quadriceps muscles and are less effective at training the critical hip extensor muscles of the posterior chain.
Hip abduction and adduction machines allow minor to excessive spinal rotation during the movement. Here is a perfect example of the mobility/stability interplay factor that I suggested above - as you try to isolate a hip abduction exercise for example, you will naturally 'shift' away from the leg in motion and experience a slight to severe degree of spinal rotation. Due to the body's natural habits of motion, it is impossible to isolate a movement or muscle without experiencing stabilization dynamics in other parts of the body.
Smith machines allow for vertical motion only, which is contraindicated in exercises such as the squat (an exercise that many young athletes perform on the Smith machine; again likely due to perceived 'safety'). In good squatting form, there should be a natural forward lean while the hips are pushing back (do not misinterpret that for me suggesting that young athletes should bent or lean forward during the eccentric or lowering phase of this exercise). This allows one to maintain a sound neutral lumbar spine position and actively generate force from the powerful hip extensor muscles. With Smith machines, this natural and safe motion is eliminated completely and lumbar flexion is promoted. "
In many cases, coaches and trainers use machines in a circuit type fashion and route several young athletes at a time through a machine-to-machine type routine. Whenever young athletes are working on timed events (i.e. the coach allows for 20 to 40 seconds at each station) you can likely be assured that the athlete is attempting to get as many 'high intensity' reps out of his/her set as possible; often at the complete disregard of their execution. With machine or free weight strength training, perfect execution is a must - in a sense that makes machines and free weights equal in this argument. Having said that, the very unnatural nature of machines make them even more of a concern from a biomechanical safety perspective with respect to 'timed' training sessions or sets.

Functionality in both sport and life is based on healthy movement, certainly not isolation. In that, Proprioceptive Neuromuscular Facilitation (PNF) plays a vital role. Often noted as a type of stretching exercise, PNF is actually a diverse and intensive concept that involves movement-based stimulus following spiral or diagonal motions (to reflect that oblique nature of most muscle angles), with the primary goal of developing motor learning through precise movements. Having said that, machine-based strength training, with its isolated format, is simply not functionally similar to innate patterns of motion that a young athlete would use on the field of play and is quite disruptive to basic physiological factors of movement such as normal timing (which refers to the naturally occurring timing of the phases of movement during a given motion).

Even with cardiovascular training, it is less than optimally productive to have young athletes use either the stationary bikes or treadmills found in most health clubs. Possessing optimal speed, agility or any other reactive locomotor's ability is based largely on hip and trunk flexibility and strength. Both cycling and treadmill running serve to limit hip range of motion and can cause decreases in the dynamic flexibility within the hip complex. Young athletes are better served to incorporate rigorous sprinting or movement-base interval training (such as Fartlek) into their training routines.

About the Author

Brian Grasso is the President of Developing Athletics which is a company dedicated to educating coaches, parents and youth sporting officials throughout the world on the concepts of athletic development. Brian can be contacted through his website at www.DevelopingAthletics.com

Article Reference

Grasso B. (2005), "Keep Kids off of Machines", Brian Mackenzie's Successful Coaching (ISSN 1745-7513), Issue 26

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