I see smart people. I have a sixth sense. That’s good because I’m not the sharpest tool in the shed, so I surround myself with people who know a lot more than I do’like scientists, for instance. Almost every week I correspond with scientists from university research centers around the globe’Japan, the United States, Great Britain, Canada, New Zealand, Australia and elsewhere’intelligent men and women who study resistance exercise, muscle growth and related subject matters. As a bodybuilder you may be interested to know that a number of them find it curious that you and I spend so much time pumping iron instead of just holding it in place. Let’s delve into the reasons why and get you thinking about a totally different way of building muscle.
Force Is King
Or so many think. Smart people don’t always agree on things, but many scientists do agree that the most essential requirement for building bigger muscles is the generation of force.
When your muscles generate force, they experience a form of stress known as tension. It’s believed that tension is ultimately converted into a muscle-building signal of sorts. Simply put, more force equals more tension, which equals a stronger muscle-building signal. Repeated over time, that results in bigger muscles.
That brings us to optimum lengths and isometric contractions. Every muscle in your body has an optimum length’that is, the length at which it can achieve its highest possible force output. When a muscle generates force without actually shortening to any appreciable degree, it’s performing an isometric contraction. A muscle can generate more force when performing an isometric contraction than it can when performing a shortening, or concentric, contraction. The latter occurs when you lift a load, such as when you extend your legs and rise to the standing position of a barbell squat. As you extend your legs, your thigh muscles generate force, which causes them to shorten.
Optimum Length:
The Best Muscle-Building Position?
If building muscle is all about generating as much force/tension as possible, you’d think that the strongest muscle-building signals could be transmitted by performing maximum isometric contractions at the target muscle’s optimum length. If that’s the case, we may have a problem. Every resistance exercise has a specific range of motion. Bodybuilders usually move a load up (a muscle-shortening, or concentric, contraction) and down (a muscle-lengthening, or eccentric, contraction) through that range of motion. That’s how we perform complete repetitions.
According to Enzo Cafarelli, Ph.D., in Isometric Exercise: Physiology and Description (www.sportsci.org), ‘Optimal length of any human muscle is the one that it obtains when in the anatomical position; standing erect, hands at the side, palmar surfaces facing front. The explanation for this is that deviations from resting length tend to misalign actin and myosin crossbridges, rendering them ineffective for producing tension. In vivo the length-tension relationship is offset by the mechanical advantage of the levers (bones) on either side of a joint. For example, when the elbow joint is fully extended, the biceps muscle is at resting length and thus capable of maximal tension production. The mechanical advantage around the joint, however, is poor because the angle of pull is directly into the joint. Conversely, when the elbow joint is flexed to 90 degrees, the muscle is shortened and is therefore on the downward portion of the length-tension curve. This is offset by the favorable mechanical advantage of the joint.’ Scientists have tried to estimate the optimum length of human muscles using a variety of research methods. I’ve read their studies, and it becomes clear that the issue is far from clear.
Many textbooks, like Dr. Cafarelli’s, suggest that when your muscles are in the neutral resting position, they are at or very near their optimum length. On the other hand, recent studies suggest that it may not be quite that simple.
Based on what is known, it would appear that some popular resistance exercises don’t allow the target muscle to be positioned at its optimum length. Take military presses for the front delts. Your arms are up, away from your torso, not down at your sides, as the neutral position suggests. When an exercise does let you get to the optimum length, as in the bottom of a barbell curl, it usually does so very briefly. So, when you do barbell curls, the load is much too light in the bottom position to demand maximum tension development. That may be particularly true with so-called slow-twitch fibers. It’s the reason researchers like Robert Fitts, Ph.D., of Marquette University propose that the best way to make those fibers bigger may be with isometrics:
‘It is true that high-load dynamic contractions recruit essentially all fiber types, but the optimal velocity for peak power in a fast fiber would be way too high for a slow fiber. In other words, the optimal velocity for the fast fiber would be near maximal for the slow fiber, and thus, due to the force-velocity relationship, force and power developed by the slow fiber would be low. Since the hypertrophy signal undoubtedly is initiated by the high force, an optimal contraction for the fast fiber would not be optimal for the slow fiber even though it would be recruited.’
So, if more force equals more tension, which equals bigger muscles, then we may be spending the vast majority of our time in the gym transmitting relatively weak’or nonexistent’muscle-building signals. Perhaps that’s why we have to perform endless reps for weeks, months or even years before seeing a satisfactory increase in size.
Is There a Better Way?
According to David Jones, Ph.D., of the University of Birmingham, ‘Our own work suggests that it makes no difference whether you train with a protocol that fatigues the muscle (i.e., produces large metabolic changes) or not. Likewise, there are reports that using eccentric exercise, where the active muscle is stretched, is the best way of promoting growth, but, again, our own results do not support this view. There is indeed a rapid phase of strength gain just after eccentric exercise, but this seems to be associated with repairing damage and there is little further benefit once the muscle is repaired.
‘Isometric contractions generate higher forces than shortening contractions, and they can last for longer than contractions involving movement (simply because you come to the end of the range of motion). I have always advocated high-force isometric contractions as the best form of training.’ I am puzzled that many people prefer to use rapid movements. The only explanation I have is that for athletes who are throwing things, it is important to train the central nervous system to activate the muscles rapidly at the start of the contraction. However, this does not apply to bodybuilders. I would suggest that [they incorporate] high-force isometric contractions [into their training].’ ALL Jones believes that force generation is the primary factor that transmits the signaling pathway, possibly by turning on IGF-1 to create an anabolic state in the muscle to increase positive protein balance there. A study that was recently reported in the Journal of Applied Physiology argues for that point. Researchers induced rodent muscles to contract isometrically, immediately followed by either shortening or lengthening actions or continued isometric actions. All three contraction modes induced the same amount of growth. Since the isometric mode was generated in all three instances, many scientists think that it’s the essential stimulus.
Optimum-Length (OL) Training
If (and it’s a big if) everything the smart people are saying about force and its critical role in muscle growth is true, then arguably a better way to train might be to make each muscle contract isometrically at its optimum length. I call it Optimum Length training, and it should enable you to to transmit the strongest muscle-building signal possible and let you sustain that signal without the repeated interruption that comes with dynamic training; i.e., performing reps.
OL training does not require that you perform maximum isometric contractions. In my opinion, unless you have a very patient training partner and the right equipment, training with MICs is just too much of a bother.
With OL training you make your muscles achieve a slightly submaximum force output, one that can be sustained for a longer time. The assumption is that it will ultimately produce a muscle-building signal that’s as strong as, if not stronger than, the one you’d get if you were to perform a maximum isometric contraction. Note that this is somewhat analogous to bodybuilders using moderate loads with conventional lifting methods for more reps rather than lifting really heavy weights that permit only a few reps, which takes too little time for successful transmission of a muscle-building signal.
Here’s some food for thought from Dr. Gregory Adams of the University of California, Irvine: ‘1) Maximal or near-maximal isometric contractions probably occlude blood flow.
2) Many dynamic resistance exercises include at least a momentary period of isometric activity. It may just be possible that this moment of very high force production before the load is put into motion is an important stimulus to hypertrophy.’
Interesting, but you’re probably wondering what you can expect from OL training. Well, I’ve been experimenting with it exclusively for only three weeks, so it’s too early to tell. The results are encouraging, but I’m far from being converted.
I spend a great portion of my waking life trying to understand what it is about lifting weights that makes muscles grow and how they can be made to grow faster. OL training is just one of the fruits of my labor.
It’s worth adding that not every scientist agrees with the force-is-king theory of building muscle. Some researchers feel that isometric contractions are great, but others feel that eccentric contractions are better’and some have completely different beliefs. Here’s something from Dr. Phillip Gardiner, of the University of Manitoba, to get your mind working:
It has been shown that isometric contractions can cause massive increases in muscle size, but that the strength increase is not proportional to the size and is relatively joint-angle specific.
Dynamic contractions, especially if they are with relatively heavy loads, not only stress the weakest joint angles through the range of motion, but also provide a very strong hypertrophic stress’eccentric contractions’when you lower the weight. In fact, eccentric contractions produce more hypertrophy and strength gain than isometric. Also, an intact blood flow with dynamic contractions allows for more strong contractions than isometric contractions which impede blood flow and therefore allow more of a hypertrophic signal.
From a purely muscle point of view, it probably doesn’t make much difference whether the muscle moves or not during activation. The trick is that exercise effects depend not just on muscle alone but an interaction among muscle, neural control and external physics.
The nervous system is tuned to the performance of tasks, not just generation of force, so it can be easier to get complete recruitment of muscles if something moves. Psychologically, that motion is visual feedback that you actually are working, which can make it easier to continue a training program. Force generation in muscle is also velocity dependent, so the amount of muscle required to move the same load depends on how quickly that load is moved. This offers a much finer degree of control over the muscle activation than might be achieved with an isometric workout.
As a real-world example, say your one-rep max for a barbell curl is 100 pounds. You might train by doing sets with 80 pounds. You can do the first rep faster, which can activate maximum recruitment, but subsequent reps become slower as fatigue sets in and causes some fibers to lose force capacity. In future workouts, when your strength is increased, however, you’ll be able to increase the speed of the reps with more control, which can lead to more muscle growth. Here’s one more interesting tidbit, this one from Thomas Burkholder, Ph.D., of the Georgia Institute of Technology:
‘If you consider muscle mass and not just girth, it turns out that muscle can be stimulated to grow in length as well as diameter. Muscle held in a lengthened position will increase mass (length) rapidly. In animal models, using immobilization to stretch the muscle, this can even lead to net mass increases at a time when the muscle girth and force capacity decline rapidly. One might imagine, then, that generating isometric tension with the muscles held in their longest position [stretch] would generate the greatest mass increases, stimulating girth and length. But it turns out that the nervous system inhibits muscle activation in those extreme positions.’
So the answer for implementing isometrics into your program may be to train the target muscle at just out of the stretch position with a slightly submaximum hold.
An OL Training Routine
So you like what the smart people have had to say, and now you want to try OL training. Here’s a basic OL routine you may want to try for a few weeks. Or you could work some of the exercises into your conventional-training routine.
I’ve been doing the OL routine three times per week on nonconsecutive days; e.g., Monday, Wednesday, Friday. On my off days I often do cardio, which may simply amount to walking briskly for 30 to 60 minutes or something more intense. Use your own judgment based on your particular bodybuilding goals.
As far as sets go, I’ve been experimenting with five per exercise. You can try fewer or more. Nothing is set in stone at this point.
1) Squat holds
The quadriceps group consists of four muscles: the vastus medialis, vastus lateralis, vastus intermedius and rectus femoris. The rectus femoris crosses the knee joint and the hip joint, whereas the vastus muscles only cross the knee joint. When your leg is fully extended, as in the top position of a squat or leg extension, the vastus muscles are at their shortest length. That substantially reduces their ability to generate force. There is some agreement that the optimum length of the quadriceps is achieved at about 70 to 80 degrees of knee flexion. To get into that position, you squat until your thighs are three to four inches above parallel to the floor. After warming up with a few light sets of slow, full squats, hold as much weight as you can in that OL position for 30 seconds. Rest 60 seconds and repeat.
Note that you can also do this on a leg extension machine with your legs held at 10 degrees or so above where your knees are at a 90 degree angle, near the bottom.
When you can hold a given load for 30 seconds, increase the load by five pounds at your next workout.
2) Faceup dumbbell holds
This exercise will work your front delts, your biceps and even your pecs. The front-delt head is in its position of highest possible force output when your upper arm is at your side, i.e., zero degrees of elevation (remember the neutral position?). As you elevate your arm, the deltoid’s force-generating capacity falls. When your arm is elevated to 90 degrees, the delt can only generate about 67 percent of its maximum force output. That’s why you do your hold down at the neutral position’to generate the most force possible.
Lie on your back on a flat bench. Hold a dumbbell in each hand with your arms straight along your sides, your palms facing the ceiling. Hold as much weight as you can in each hand for 30 seconds. Don’t let your arms drop. Rest 60 seconds and repeat.
3) Facedown dumbbell holds
This one works your rear delts, triceps and lats. It’s the opposite of faceup dumbbell holds’and it’s surprisingly tough. Lie on your stomach on a flat bench. Hold a dumbbell in each hand, with your arms held straight at your sides, palms facing the ceiling. Hold as much weight as you can in each hand for 30 seconds. Don’t let your arms drop. Rest 60 seconds and repeat.
4) Standing calf holds
You’ll need a standing calf machine or a 45 degree leg press. With the balls of your feet on the platform and your heels hanging off, lower your heels as far as you can, and then, using as much weight as possible, hold your calves in the stretch position for 30 seconds. Squeeze your calves hard during the set. Don’t let the balls of your feet come up off the platform.
5) Neck holds
Wrap a barbell plate in a thick towel’a thick one! Lie on your back on a flat bench. Stabilize the plate on your forehead with your hands. Tilt your head back slightly and hold the weight in that position for 30 seconds. Rest 60 seconds and repeat.
6) Stiff-legged deadlift holds
To work your hamstrings, you use stiff-legged deadlifts, but rather than actually moving the barbell, you hold it out in front of you at about the halfway point, around knee level. You won’t be able to use much weight, but that’s okay. With your legs just slightly bent, you should feel an incredible stretch in your hamstrings. Hold as much weight as you can for 30 seconds, rest 60 seconds and then repeat.
7) Leg-lift holds
You can do these lying on a flat bench or on the floor. Keep your legs straight and lift them four to five inches off the bench or floor. Hold in that position for 30 seconds as you press your lower back into the bench or floor. Really squeeze your abs hard. If you need more resistance, hold a dumbbell between your feet or attach a low cable to your ankles. Rest for 60 seconds and repeat.
Editor’s note: Visit the author’s Web site, www.robthoburn.com, for more articles, discussion forums and O.L. Training info. You can also sign up for his free newsletter. IM
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