The stimulus for positive adaptive change has many factors. Clearly, there is a strong cardiovascular component, as your cardiorespiratory system services the mechanical functioning of your muscles. Thus, the higher the intensity of muscular work, the higher the degree of cardiovascular and respiratory stimulation. There is also a large production of accumulated by-products of fatigue, in that metabolic wastes such as lactic acid accumulate faster than they can be eliminated by the body. These effects create an environment in which certain growth factors are released and
This graph illustrates what happens to your strength as you perform a set of exercises. Time is along the bottom (x-axis), and units of force are along the side (y-axis). The gray bars represent the machine's resistance (weights) steady at 75 units. Each set of white bars indicates the progression of the set and the ever-weakening strength of your muscles.
the first stages of muscle growth are stimulated/' Load, or weight, is a part of this process as well. Exposure to heavier weights causes microscopic cellular damage that initiates the muscular adaptation and seems to be essential for stimulating increases in both muscle and bone mineral density.7
All of these factors are present and contribute to the stimulation process when the mechanism of inroading, or weakening, of the muscles is employed. High-intensity muscular contractions, during the course of which muscle tissue is made to weaken, is a powerful stimulus for positive change/ It is crucial, therefore, for all trainees to have a firm intellectual understanding of what it is that they are striving to achieve. We have found it helpful to use the inroading diagram (Figure 4.2) to help explain this process.
At the beginning of a set, your strength is untapped; let's call it 100 units of force. You will not choose 100 units of resistance, however, but rather 75 units, to oppose your strength. For inroading to occur, the resistance to which you expose your muscles must be meaningful, which is between 75 percent and 80 percent of your starting level of strength. If the resistance you select is too light, your muscles will recover at a faster rate than they fatigue, with the result that no inroading will occur. Using a slow protocol, you will proceed to perform your repetitions, moving the weights up and down. (We would typically have you employ ten seconds on the positive, or lifting, phase and ten seconds on the negative, or lowering, assuming that the equipment has correct cam profiles and low friction.) This slower speed of lifting eliminates momentum, increases safety, and keeps your muscles under load for the duration of the set.
With each passing moment, your strength diminishes, with the result that your force output is now starting to drop, and your rate of fatigue and fiber involvement increases. You have now lost some of your initial 100 units of strength, but your muscles are still stronger than the 75 units of resistance that you are lifting and lowering. You are now perceiving that the repetitions are getting harder. Your body instinctively doesn't like to be fatigued so quickly, and you are starting to receive negative feedback, which typically manifests in a fervent desire to quit the exercise. Nevertheless, you soldier on, attempting to maintain a continual loading of your muscles and increase your concentration so as not to break form and unload your rnus-
cles. As the difficulty level increases, you may grow anxious as you sense that muscular failure is approaching. (This anxiety is a normal reaction.)
You will begin to really struggle at this point, and your instructor should try to keep you focused by encouraging you not to try to speed up, rest, or pause during the movement, all of which will unload the muscles and provide rest, which is the opposite of what you are striving to accomplish. If you weren't being supervised, you would probably quit at this juncture, but you are encouraged to try one more repetition. This last positive portion of the repetition is now so difficult that it may take you fifteen, twenty, or even thirty seconds to complete. As you slowly begin to reverse direction and lower the resistance, the weight begins to overtake your strength. You attempt another positive repetition, but the weight is not moving. Your instructor now tells you to attempt to contract against the resistance (it's still not moving) while he or she counts to ten. Your rate of fatigue is increasing rapidly now, and your strength continues to diminish well below the resistance level. At the end of the instructor's count, you unload from the weight. By the time the set is finished, your strength has been reduced to approximately 60 percent of what it was prior to starting the exercise, resulting in an inroad of 40 percent being made.
This whole process occurred over a span of roughly two minutes, but in that time, your muscles became 40 percent weaker. This occurrence represents a serious "threat" to your body, because it was not aware that you were simply in a gym making weights go up and down. For all it knew, you were fighting for your life with a mountain lion. To the body, this was a profound metabolic experience, and at the end of that experience, it couldn't move. Mobility is a preserved biologic function: if you can't move, you can't acquire food, and you can't avoid becoming food for other prey. This experience represented a profound stimulus, to which the body will respond, if given sufficient time, by enlarging on its strength reserves so that there will be at least some strength left over the next time such a stimulus might be encountered. Of course, now that you understand this process, you will employ slightly more resistance during your next workout to stimulate your body to produce another round of metabolic adaptation.
Bear in mind that as you fatigue during this process, and as your force output drops, you will feel the window between your force output and the resistance you're using starting to close. You'll develop an almost instinc tual sense of panic, a feeling that you're not strong enough to meet the resistance you're under. This is the "make-or-break" point in the set. If you understand that what you're trying to do is achieve a deep level of muscular fatigue, you can override the instinct to attempt to escape. Escape in this context can take the form either of prematurely quitting and just shutting down or of attempting to wiggle and jab at the weight to momentarily get out from under the load.
We tell our clients, "We don't care if the weight bogs down, and we don't care if it stops moving. Just keep pushing in the same manner that you did in the beginning, and if it stops moving, don't panic: just keep pushing. It's not important at the end if the repetition is completed." An understanding that your instincts run counter to achieving this degree of fatigue, and that you have to intellectually override your instincts in order to achieve it, is crucial. The most important thing for you to grasp is the nature of the process. To be able to push to the point where physical activity becomes a stimulus for productive change, it helps to understand that it's OK to feel a little anxious or panicky during the set. After all, the purpose of the exercise is not to make the weight go up and down; it is to achieve a deep level of inroad, to reach the point where you can no longer move the weight but still keep trying. If you have that degree of intellectual understanding, then you will be able to override the instincts that otherwise would intercede to prevent you from stimulating the production of a positive adaptive response from your body.
A logical question arises: What point of fatigue should the beginner target? Is it the point at which another repetition isn't possible? Or is it—at least during the first few workouts—simply the point of discomfort? It has been our experience that most clients, even beginners, should try to go to a point of positive failure right from the get-go. If you find that you have misjudged the resistance you should be using and are performing the exercise for too long (more than ninety seconds), keep going until you hit positive failure, and increase the weight by approximately 5 to 10 percent (or whatever amount is required) to get you back under the ninety-second time under load.
Admittedly, there will be trainees who are or have been sedentary and therefore are not used to exerting themselves. For them, the entire concept of inroading their muscles will represent such foreign territory that sometimes they'll quit the exercise well before they've reached a point of positive failure. In such instances, we use their point of voluntary shutdown as a tentative definition of positive "failure" for a workout or two, until they start to develop a skill set and better tolerance for exertional discomfort that allows them to go to true muscular failure. Otherwise, if clients are able, we will have them go to failure right from the outset.
A lot of times, that failure point will be determined by the trainee's current capabilities and level of toleration of exertional discomfort. Once an individual gets acclimated to this condition, we encourage inroading to the point of momentary muscular failure (positive failure). We believe that this is safe to do, because what you can bring to yourself is pretty much limited by your current capabilities; you can never bring more to yourself than you're capable of handling.
A trainee who is relatively well conditioned and is going to true failure should perform the Big-Five workout once every seven days. There are exceptions: the recovery interval needs to be predicated on the individual's level of intensity during the initial workout and the muscle-mass level at baseline. A petite, 100-pound woman whose intensity level is such that her failure level is determined by her toleration of discomfort could easily work out twice a week and not have any concerns about overtraining. Then again, a relatively athletic young male who weighs a solid 170 pounds and is able to go to true muscular failure may need to work out only once every seven to ten days. Even that 100-pound woman will eventually have to add recovery days to her time off between workouts as she grows stronger, until she too is training only once a week or less frequently.
The seven-day rest is predicated on the absolute mechanical work that a person is performing: are the weights significant, and is the metabolic cost high? A person who is not capable initially of performing enough mechanical/metabolic work to make that seven-day recovery a requisite may initially benefit from slightly more frequent training, but otherwise, all things being equal, once every seven days is an excellent frequency with which to start.
If you're doing everything appropriately—working hard enough, keeping the volume of the workout in the realm in which your recovery can manage it, and keeping proper track of your performance—the amount of resistance you're using should progress in a stepwise fashion, and you should be matching or bettering your time under load at an increasing resistance from workout to workout. Once that situation stops occurring, and you are starting to have difficulty with progression, that is an early marker that you need to start inserting more recovery days, because you are now accumulating enough strength to produce enough of a workload that it is proving difficult for you to recover at that particular frequency.
It has been our observation that, by and large, people who come to a personal training facility want to get going with a program and settle into a routine. Often enough, if you just settle them into the routine, and they get used to "This is my appointment time on this day, and this is when I exercise," long-term compliance is established right from square one. Most commercial health clubs turn over the vast majority of the people they sign up in less than twelve weeks, whereas the average person in our facilities has been there for four to seven years, and some of them have been there for ten years, because the compliance is enhanced by a manageable volume, frequency, and regularity that becomes a comfortable component of their lifestyle.
We encourage our clients to move quickly from one exercise to the next. Thirty seconds to a minute is typical for them to make the move and get adjusted into the next piece of equipment. There are metabolic conditioning benefits to be achieved by moving briskly. As you accumulate the by-products of fatigue, the amount of resistance that you can use drops, so the relative degree of inroad that you're achieving as you progress through the workout is increased.
Ideally, you should move briskly enough from exercise to exercise that you're huffing and puffing and not inclined to carry on a conversation with your instructor or workout partner. The pace should be such that you pro duce a fairly profound metabolic effect, but you shouldn't move so quickly that you feel light-headed or nauseated. At the other extreme, you shouldn't pace yourself to the point where you feel so completely recovered that it's as if you're starting the first set of a workout sequence on every movement.
The workout record sheet should be standardized. There should be a space for the date of the workout, the time of the workout, what exercises are performed, how much resistance was used, seat position (where applicable), and cadence employed—or time under load. It's also not a bad idea to record the elapsed time from when the first exercise commenced until failure was reached on the last exercise in the program.
If you are keeping track of your time under load, you may also find it helpful to keep a record of the difference between the total accumulated TULs and the elapsed time of the workout, in order to keep rest intervals fairly constant. This is done by noting the elapsed time of the workout and then totaling all the TULs for the workout and subtracting that number from the elapsed time. The remainder will equal your total rest time for all of the movements for that workout. That figure should also not display massive increases. For example, if your w orkout record reveals big improvements in performance, but when you look at your total time under load minus the elapsed time, you find that your total rest time for the workout has increased by five minutes, then maybe your performance hasn't increased by as much as you thought it had.
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