What is it really?

Whether it be for improving activities of daily living (ADL) for seniors, reducing the potential for hamstring injuries among sprinters, or increasing swing or throwing velocity among tennis, golf, and baseball players, or helping first responders “get the job done,” improving muscular fitness is a must. But what are we really training? Is it strength, is it power, is it endurance, is it range or ease of motion, or is it precision and control of movement? Of course, it is all of these.

Of course, traditional training methods use a variety of modalities to work on each aspect of muscular fitness. They require considerable planning, time to execute, and multiple training modalities (i.e. $$$). When we train for muscular fitness, one of the key considerations is how to optimize load across the range of motion. This is lead to training concepts such as accommodating resistance, dynamic variable resistance, and so on.

Another key consideration is “functional training.” Beyond absolute or relative muscular strength and muscular endurance, trainers should really focus on an individual’s targeting outcomes, typically addressed through:

  • Physical Therapy to reduce injury risk, facilitate injury recovery and mitigate the potential for re-injury
  • Activities of Daily Living (ADL) improvement for the frail, disabled or elderly
  • Sports Performance (recreational or competitive)
  • Work-related conditioning for industrial athletes (materials handlers, first responders, etc.)

How can we achieve results with each of these groups and, in turn, build or retain our client base? What should we consider when addressing the outcomes noted above? Are you addressing:

  • Neuromotor Unit Activation/Fiber recruitment patterns in across the appropriate kinetic chain(s) of specific movement(s) or task(s)
  • Multi-joint, task-specific movement precision via enhanced motor control
  • Increasing absolute and relative strength to meet or exceed the functional requirement(s) of the task(s)
  • It is not simply muscular strength and endurance across first line fibers recruited. Rather it is critical to address all associated motor units (MUs).
  • Therefore, it is also proprioception; calibrating or retraining the sensors in the body that support kinesthetic awareness.

We typically address the above through any or all of the following (please excuse in advance any apparent oversimplification necessary to keep the overall context of this commentary at the forefront):

  1. Isotonic – With such fundamental strength training systems (calisthenics, free weights, kettle bells, selectorized machines, etc.), all we must do is overcome resting inertia and sustain the inertia of movement which is then limited only by gravity, load mass and strength necessary to overcome the both forms of inertia. The weakness in these types of exercise is that they are not always readily modifiable to address specific needs, body parts, targeted specific kinetic chain(s), or atypical movement patterns (e.g., range of motion or pain-based limitations). In other words, while they can train muscles associated with a particular activity, they are difficult to train the specific movements required by those activities in a manner consistent with the performance specific speed, strength and associated power variables required by those activities.
  2. Isokinetic – This system seeks to achieve maximum speed across a range of motion with specific variances in force generated primarily due to changes in leverage through the range of motion. A great mode of training but find a low cost system to use. Are isokinetic modalities fiscally practical or functionally variable according so specific movements, joint conditions, body structure or specific tasks at a reasonable cost?
  3. Isometric – Typically these are maximal contractions against immovable resistance. They do not address any of the points associated with 1 or 2 above, though they can be useful as part of the program if used properly in a total systems approach to muscular conditioning.

Consider what research tells us:

What has research reported? Work by Kallio, et. al.1 argued that there is little question optimal motor unit (MU) activation in submaximal work is typically achieved with concentric (isotonic) contractions, even when compared to eccentric (think plyometrics) and isometric contractions. Bigland and Lippolf2 report fewer MUs are activated in response to a specific load with eccentric contractions when compared to concentric contractions. However, when maximal voluntary contractions (MVC) are required (specifically isometric contractions), both motor unit discharge rate (MUDR) and total MU activation isometric contractions occur. In fact, with isometrics contractions Fallentine and associates3 demonstrated that there appears to be something of a rotation of MU recruitment as a way to mitigate fatigue during extended contractions. Further, Clamann and associates4 extended this concept of rotation to various MUs. They reported that MUs have tension specific firing patterns that are dependent on force requirements which were task specific in nature. This “… allows fine control of weak movements and rapid production of powerful movements.” 5

Enough on the very rudiments of what is a plethora of research. What is missing among trainers is that too many simply think about training outcomes. This is generally at the expense of failing to consider (i.e. lack of understanding) the merits of why we should train people in a specific way. So why does any of this matter and why do so many trainers talk the talk while failing to walk the walk?

I choose to opine that it is because the industry extols and markets “functional training” or “functional fitness,” but far too few really know what these terms mean, let alone how to apply them properly. Many see the terms bandied about in the sales and marketing brochures of seminars and conferences. Their use is intended to secure the reader’s participation. These events are too often allegedly designed to foster professional enrichment but simply bring the latest “buzzwords” to their attempt to secure more registrants. You see them blindly nodding to the exercise gurus in their lemming-like commitment in hope of securing more clients or better retention of existing clients over time.

Let’s try to simplify it all and consider “where the rubber meets the road.” Think locomotion, dynamic balance, aging, strength, speed and thus power-related performance. It is not simply muscular strength or endurance or power, it is the integration of these three with neuromotor control and MU recruitment patterns that represent a bona fide functional training approach.

If you think back to your anatomy, physiology, and kinesiology training, recall that the body is an integrated system. Whether it be athletic performance, endurance, athletic skills, or the management of daily activity demands; individual muscle fibers, fiber groups, the nervous system, brain, and proprioceptors (the sensory systems that tell the brain where body parts are in space, speed of movement, angle of joints, etc.); are part of every movement requirement. This occurs regardless of how simple or complex, voluntary or involuntary, slow or fast the movement is. If any of these components of movement are deficient, results will suffer. There are three possible outcomes:

  • less than optimal performance of the desired task
  • total failure to perform the task
  • either of the above may lead to injury

As we age, motor fiber recruitment patterns and MVC force levels deteriorate, even with training. So for the aging person, balance, reaction to external forces and activities of daily living can become problematic (think getting up and downstairs, into or out of a chair, bathtub, or bed; to say nothing of fall prevention and the associated potential for fractures). For the recreational athlete, reaching for the tough dig on the handball court, reacting to the moguls when skiing, maintaining clubhead speed in golf, controlling the softball throw, walking down a mountain trail with an uneven surface when hiking or trail biking, all become skills and abilities that can suffer the results of aging. For the senior, it can be as simple as getting around the house with comfort and ease.

Oh my, what is a competent trainer to do?

  1. First, think of a particular athletic skill (shooting a jump shot in basketball) or ADL (getting in or out of the bathtub).
  2. Second, think of all the factors that go into it, not just strength, speed, power or endurance of a muscle or muscle groups, think of how the brain gets the signal to the appropriate package of MUs along the way.
  3. Third, then and only then think about how to properly train an individual to meet the specific goals and objectives they have, as well as their current capabilities.
  4. Fourth, develop an integrated training program that addresses one, two and three safely and effectively.
  5. Determine a baseline and track changes over time so you can modify your program appropriately.

At this training (calisthenics and their infinite variety of types), selectorized weight training, free weight training, air pressure systems, water-resistance systems, etc., etc., etc. All have their purpose and all have their merits and demerits in specific circumstances. Permit me to suggest one more item point you may be thinking suspension training, plyometrics, cross fit, body weight-based for you to consider placing in your bag of tricks as you develop training programs for your athletes or clients that actually enable you to address 1-5 above.

There is a singular exercise device that has been available to trainers, coaches, professional and amateur athletes, and aerospace scientists for over 50 years, yet few know of it. Even fewer know how to use it properly or what it can really do for most aspects of muscular fitness and task performance. It’s not sexy, it’s not glitzy, it not cumbersome, and it is highly portable. It has successfully enhanced the physical performance capabilities of Super Bowl champions, Stanley Cup champions, Olympic champion cross country skiers, Masters golf and track and field champions, NBA players, Astronauts in space flight, the physically challenged, as well a people of every walk of life, including seniors.

It is probably one of the most effective total body conditioning devices that you have never heard of. It is “The Exergenie Variable Resistance Trainer.” So why is the “gym in a bag” not in everyone’s bag of tricks? I have no idea. The patent holder calls it “One Unit — Infinite Use.” No, I am just a disciple not the holder of the patent.

With one person applying its use, it can address the isometric and isotonic training needs of virtually any muscle or muscle group, be it single-joint motion or multi-joint applications. Its application can be made appropriate to virtually any athletic movement requirement for performance, rehabilitation or work conditioning (i.e., industrial/occupational injury prevention and management). It also can be applied to seniors and virtually anyone with “functional limitations.” The unit can also be utilized to promote flexibility, proprioceptive neuromuscular facilitation, and when properly applied, addresses the MU recruitment concerns previously discussed.

There are those who know of it that argue: “But it does not support eccentric training (resistance to muscle lengthening)!” While true in the base case, there are three counterpoints to that:

First – Other than very expensive concentric and eccentric resistance devices (Kaiser type equipment) and plyometric forms of exercise, eccentric training is not a capability of the vast majority of other exercise modalities, including many current “popular” approaches (training tools like sleds, parachutes, rope swings, chains on barbells, etc.). These also do little for eccentric resistance training unless someone increases the load on the return to the starting position after a concentric contraction.

Second – Another key consideration is that with most of the speed training modalities, mentioned above, as well as with traditional strength training modalities (including resistance band and suspension training), once the athlete breaks the inertia of rest reaches the speed point where the coefficient of friction becomes flat, or overcomes the load (pull of gravity on total mass being moved), with weights, a resistance band or suspension system, or the cam system on selectorized machines, there is limited potential to increase the load and the movement.

Therefore, such movement is generally limited only by the fatigue of the fibers recruited, not by substantial increases in the resistance itself. Where the resistance to be increased or decreased above or below the threshold to break the inertial of rest and be modifiable to accommodate the varying force-generating capabilities within a given range of motion, the result would be the recruitment of more MUs. This in turn would increase the total work performed before failure.

With the Exergenie, the load continues to rise throughout the range of motion the harder the athlete pushes (against the belt or the handle) until the effort has to cease. Using the speed line system as an arbitrary example provides the coach with infinite choices such that he can shorten the time and increase the resistance (ATP-PC emphasis) to top at 10 sec on day 1 or increase the time and reduce the load to top out at 30 seconds (day 3) to train the anaerobic side of the lactic acid system. Do something else on day 2. Or do both on the same day on day 5 thus really loading the fast-twitch fibers to pre-fatigue with the short bursts then working lactate production/removal cycles to tax the oxidative glycolytic or crossover fibers a bit more. One might think of it as intensive interval training with a rope! The point is, the Exergenie approach represents an efficient and flexible supplemental training tool when added to what you may be currently doing.

Third – Whether it be directed toward eccentric, isotonic, isokinetic or isometric capabilities, it’s all about taxing the energy supply systems (phosphate and lactic acid systems for our purposes) in higher intensity activities (i.e., too much results in failure of muscular contraction) in an acute bout of exercise. This in turn is followed longitudinally by adaptive responses in energy substrate availability, lactate clearance improvements, fiber size or number depending on training systems and the contractile properties of the MUs being recruited.

One can argue about the concept of differential fiber types and recruitment patterns, but it still comes down to how you increase total work performed before decrements in performance (fatigue). Consider an example of training the primary movers first, and then secondary and tertiary movers in a classic weight training circuit scenario. Promoting fatigue of the primary movers first is followed sequentially by stimulating and fatiguing secondary and tertiary movers across properly timed sets and reps.

Similarly, the Exergenie concept of starting each contraction with a maximal isometric effort for 10-15 seconds followed by a maximal isotonic movement with accommodating resistance via the rope control procedure for an additional 15-20 seconds, taxes the first order of recruitment MUs then calls the second and perhaps third-order fibers to complete the movement. In this instance, you would be recruiting the first-order fibers and MUs within a given muscle or muscle group. Then as those MUs fatigue, the secondary and tertiary MUs are recruited and thus stressed across the range of motion in a single contraction or series of contractions. Pretty neat, no? Of course, the work-rest cycle and variety of exercises appropriate to a given functional outcome objective are also important. However, they will be the focus of a separate discussion.

By the way, now that you better understand how the Exergenie Trainer and Exergenie Speedline system can assist with all of these concepts with and without a partner, consider that it can do all this in the hands of a competent trainer at less than $300 a unit? If you are a trainer who truly is passionate about developing your skills and your client’s capabilities, you might want to learn more about the device that “few have ever heard of” and even fewer know how it can be applied.

However, how about one more brain teaser? We know eccentric training is intended to improve recruitment patterns, strength, speed and power performance. The Exergenie, through concentric exercise, the same muscle cells and recruits the same MUs to increase stored ATP-PC substrates, while promoting improvement in lactate clearance. If the baseline functionality of the metabolic and contractile elements of the MUs improve, would this not likely translate into an improved capacity to train with eccentric movements of the same MUs before fatigue as well?

In summary, the Exergenie may be worth a look for:

  1. Adding another time-efficient modality for improving the two primary energy supply stems associated with power and speed sports
  2. Increasing maximal concentric contractile strength (thereby raising the baseline capability for training and relative time to failure)

Improving and refining the muscle fiber recruitment patterns to reduce fatigue. This, in turn, increases performance in shorter-term activities (running a pass route or driving the lane) or increasing time to fatigue in intermediate-length activities (think a period of wrestling, a shift on the ice hockey rink, a police officer in a ground fight, or a firefighter attempting to knock carry an attack pack up four stories, force a door, and knock down a fire.

Respectfully yours,
Dr. Paul C. Di Vico, FACSM, CHFD, CES, CSCS

Applied Physiologist
13771 N. Fountain Hills Blvd., Ste. 114-314
Fountain Hills, AZ 85268
P~801-566-1899, F~801-880-1160

Since 1976, Setting the Standard for Job-related Physical Performance

1 Kallio, J. et. al., Motor Unit Firing Behaviour [sic] of Soleus Muscle in Isometrics and Dynamic Contractions, PLoS One(2): e53425-53431, 2/2015.
2 Bigland, B. and O. Lippolf, Motor Unit Activity in the Voluntary Contraction of Human Muscle, Journal of Physiology, 125: 322-335, 1954.
3 Fallentine, N. et. al., Motor Unit Recruitment During Prolonged Isometric Contractions. European Journal of Applied Physiology, 67(4): 335-341, 1993.
4 Clamann, H. et. al., Motor Unit Recruitment and the Gradation of Muscle Force. Physical Therapy, 73: 830-843, 1993.
5 Clamann, H. et. al., Motor Unit Recruitment and the Gradation of Muscle Force. Physical Therapy, 73: 830-843, 1993.

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