Someone recently asked about a “sports specific” workout. A good workout for an athlete is one that safely and effectively works all the major muscle groups in the body, with the highest priority increasing the athlete’s resistance to injury during practice and competition. This does not mean doing a bunch of plyometrics and Olympic lifts and so-called “functional” exercises that mimic the skills of the sport while using weights or weighted implements. What it does mean is performing exercises for all the major muscle groups based on muscle and joint function, not sport movements, in a manner that strengthens without being unnecessarily hard on the joints. Additionally, it means performing exercises specifically to strengthen the areas of the body most often injured to minimize the chance or severity of injury to those areas. Direct neck work for athletes in contact sports, knee extension and flexion for runners, etc.
While we’re on the topic of knee flexion, properly designed seated leg curl machines (with a coupled movement arm) are better than prone leg curl machines for several reasons. Earlier leg curl machine designs used a prone body position because they were based on the designs of leg extension and leg curl attachments developed for flat benches. The seated position for later knee extension machines was obvious since this was the position they were performed in on the bench, but rather than design knee flexion machines based on joint function, earlier machines just copied the exercise as performed with the equipment already available.
A prone leg curl is superior to an improperly designed seated leg curl machine, however (just about every leg curl machine other than Nautilus, MedX, and SuperSlow Systems). The worst seated leg curl designs incorporate a pad which presses down on the top of the thighs, often with handles for the user to hold to brace against being pulled forwards. This is a very poor method of countering the changing reactionary force over the range of the exercise, and these designs typically have a seat bottom which extends all the way to the back of the knees rather than ending just a little past the ischial tuberosities of the pelvis (the “sit” bones), which means not only are you sitting on the muscles you are attempting to contract, but you also have a restraining pad pushing the thighs down into the seat.
On a prone leg curl machine the weight of the thighs is on the quadriceps, not the hamstrings which you are trying to contract, which is a big improvement.
A properly designed seated leg curl also has the advantage of easier entry and exit and with the coupled movement arm reactionary force is countered without the need for the user to pull (prone designs) or push (seated designs with thigh pads and handles) with the arms to maintain proper positioning and alignment. It is also easier for people to learn the exercise when the movement is occurring in front of them (Ken Hutchins’ heirarchy of motor learning difficulty).
The optimal seat design for the leg curl is very different than what is optimal for a leg extension, which is also a big problem for companies which make “combo” machines providing both functions. The Exerbotics leg curl is a great example of how not to design a leg curl machine:
1. A thigh restraint with handles is a very poor solution for countering reactionary force and maintaining proper positioning and alignment during seated leg curls. The Exerbotics machine uses a thigh restraint with handles instead of a coupled movement arm (which can be designed to work in both flexion and extension with a simple position change).
2. The seat bottom should only extend far enough to provide support for the pelvis so the user is not sitting on the hamstrings while trying to contract them. The thigh restraint pressing down on the thighs makes this even worse. The Exerbotics seat bottom extends too far.
3. A seat belt is required for optimal countering of reactionary force during leg extensions while minimizing tension in the neck and shoulders from pulling up on the handles, and also a better solution for countering forwards reactionary force along with a coupled movement arm during seated leg curls. The Exerbotics machine has no seat belt.
Although the point isn’t to bash Exerbotics specifically, since most equipment companies get this stuff wrong, I should point out in addition to the problems related to using motorized resistance the rest of Exerbotic’s machine designs contain numerous flaws.
On a related topic, one of the other considerations of machine design is avoiding positions of active or passive muscular insufficiency – something Arthur Jones was actually trying to do in the design of the early Nautilus compound biceps and triceps machines. Although I much prefer triceps extensions and arm curl machine designs which position the upper arms at around 90 degrees of shoulder flexion, those machines certainly produce an intense sensation when used correctly. Jim Flanagan put me through a set on the Nautilus compound triceps and biceps machines (pictured above, with Jim Keen in the compound triceps machine, and the compound biceps machine to his right) and shortly afterwards I did a set of weighted dips and weighted chin ups and the effect was impressive. The pump was almost uncomfortable and my arms still feel “heavy” almost 24 hours after the workout.
Have to head out to the beach so that’s all for now, but there’ll be more on this later.