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...one would expect to find clear evidence that dynamic exercise is better than static exercise for improving performance in dynamic functional activities. Surprisingly such evidence has not been strong. -Medicine and Science in Sports and Exer...

...one would expect to find clear evidence that dynamic exercise is better than static exercise for improving performance in dynamic functional activities. Surprisingly such evidence has not been strong. -Medicine and Science in Sports and Exercise No. 271 7. Isometric Questions and Answers: The Current Science Will isometrics make me stow? It's perhaps intuitive to imagine that by training very slowly—or, indeed, not moving at all, as is the case with isometrics —an athlete will adapt by becoming slower. In fact, studies show that this notion is incorrect: static isometric training can increase speed and jump height just as effectively as explosive training Z One must realize that there is a high correlation between maximal isometric strength and movement speed. An increase in strength brings about an increase in movement speed. -Dr Dietmar Schmidtbleicher3 How can not moving make you faster and more explosive? There are two primary reasons. The first reason has to do with the physics of speed. Naturally explosive movements—from jumping, to hitting a baseball, to cleaning a barbell—typically begin from a dead stop. The force-velocity relationship* demands that high levels of force are required in the initial stages of such movements:...movements such as the vertical jump start from zero velocity. Thus even slow speed strength is critical for accelerating the body early in the movement." -Morrissey, et a 1.4  50 Isometric Force-time curve FORCE (kg) 0 100 200 300 TIME (ms) The degree of correlation between isometric strength and movement speed increases when the load gets heavier. Why? Because speed-strength requires starting strength.^  Nature bears this out. Fast, explosive animals like lions often possess a significant amount of muscle mass. So do sprinters, compared to marathon runners. Strong muscles and fast body movements go hand-in-hand. The old notion that a strong person must be "muscle bound" is a long-dead myth.£ The second reason has to do with fiber types. In order to be fast, an athlete primarily requires powerful fast-twitch muscle fibers—these Type II fibers are capable of contracting up to ten times faster than their slow twitch cousins. However, sports researchers now understand you don't necessarily need to train your fast-twitch fibers by moving quickly: you can also develop them by exerting large levels of force. (This is due to Henneman's size principle; large fibers are only recruited when really necessary, such as under a large load. Fast twitch fibers are the largest type of fibers.) Paradoxically, isometric training involves higher levels of force than dynamic training: as a result, it develops fast twitch fibers and can make an athlete faster —even if they aren't training for speed. This increased speed from isometric strength training doesn't just apply to simple linear movements like jumping; it also transfers to more complex athletic motions, such as cycling, sprinting, climbing and martial arts striking power.2 If you want to train fast-twitch muscles, you have to move fast, right? No, you don’t. In fact, you can increase your injury risk in doing that. Being fast-twitch muscle only means that it’s the fastest to fire and the fastest to fatigue. Trying to build that by moving fast works your momentum much more than your actual muscle. The difference in which muscle fibers you build comes not from your training speed, but your training intensity. -Jarell Lindsey^ As an added bonus, isometrics not only compares well to explosiveness training in terms of results, it is also far safer for the joints. A study published in the Journal of Strength and Conditioning Research concluded: Plyometric training has been shown to place large stresses on the body, which can lead to a potential for injury, whereas explosive isometric training has been shown here to provide similar benefits to that of plyometric training with respect to the measured variables, but with reduced impact forces, and would therefore provide a useful adjunct for athletic training programs within a 6-week time framed is isometric strength only angle-specific? If you train an isometric exercise with the muscles held at one angle—let's say, with the biceps at 90 degrees—your muscles rapidly become stronger at holding that angle. This is unquestionable, and supported by numerous studies.^  However, many researchers have questioned how much that strength gain is angle-specific—whether it only applies to the trained angle—or whether that strength transfers to alternate, untrained angles. How far does that developed strength overflow? 20 degrees? 30 degrees? The entire range of motion? In training articles you will sometimes read statements to the affect that isometric strength only transfers 20 degrees from the trained angle. This idea is typically repeated as if it were gospel, however you rarely see this kind of dogmatic statement in the scientific literature, because there is little consensus about the specific nature of strength transfer.!!^ What the studies do generally show is that although the training gains are greatest at the training angle—angular specificity—there is still some transfer at all other muscle angles, whether those angles are trained or not: it's just that the gains at the untrained angles are not as great. It seems that the law of diminishing returns applies; the further from the training angle, the lower the transfer: In this 12-month study, the quadriceps were trained only at a 60-degree angle. After a year, strength also increased hugely at 90 and 30 degrees—untrained angles. The greatest strength gain was at the 60-degree training angled  This means that those critics who argue that angular-specificity means that isometrics training doesn't build "complete strength" do not fully understand the issue. Angular specificity does not mean that if you train in one position, you only become strong in that position. (It would be absurd to suggest that a biceps muscle which is inhumanly strong at 90 degrees would suddenly become a weak biceps at, say, 40 degrees.) All angular specificity means is that if you only train at one position, your strength gains are greatest in that position. It doesn't mean that you gain no strength in other angles—you do....as with all strength measurements, there is a specific force or torque versus joint angle curve for each type of muscle contraction, so that it is highly unlikely that a strength increase would be confined to a very precise angle and nowhere else in the range. -Verkhoshansky^ Some researchers have even doubted the notion of angular specificity at all; reasoning that, the different strength­ potentials of muscles at various angles are due almost entirely to the length-tension relationship. This is a well-established law of myology which states that skeletal muscle possesses its highest strength at an ideal length, typically it's resting length (often, but not exclusively, the "midpoint" of an exercise). Muscle strength proportionately decreases when stretched or shortened beyond this point, due to the function of elastic proteins (such as actin) within muscle cells.15 other scientists have cast doubt on the research methods of studies which have emphasized the concept of angular specificity, finding that—when mathematical errors due to body mechanics are accounted for—differences in isometric strength at divergent angles are a function of leverage, rather than muscle activity.^ Can isometrics help me lose weight? It has been understood for a long time that exercise—plus sensible nutritional choices—will result in fat loss. Typically, very active exercises—such as running or cycling—are selected as optimal weight-loss exercises because they burn a relatively high number of calories. Isometrics, on the other hand, is a highly energy efficient form of exercise.TZ As a result, the practice of isometrics burns relatively few calories. For this reason, isometrics is not traditionally viewed as part of a potential fat-loss protocol. In 2007 a group of researchers from the Departments of Physical Therapy in Loma Linda University and Azusa Pacific University developed a single-blind randomized study to see whether isometric exercise worked to encourage fat-loss. A study population were given a brief isometric training program to follow on a daily basis. The subjects were not required to follow a rigid dietary program, but were instead given five simple dietary recommendations (for example: try to eat healthy foods; drink eight glasses of water a day; etc). The results were dramatic: In the present investigation, it is not surprising that with isometric training, there was a marked increase in muscle strength. Thus, the isometric exercise program worked well in terms of increasing muscle strength. It is significant that there was a 20% increase in muscle strength with only seven minutes of work each day. But the program, while increasing muscle strength, was equally matched by the benefits of weight and girth loss. The loss in girth after 2 weeks for the average person at the waist was 3.0 cm which was equivalent to one pant or dress size. But the program, while increasing muscle strength, was equally matched by the benefits of weight and girth loss. The loss in girth after 2 weeks for the average person at the waist was 3.0 cm which was equivalent to one pant or dress size. After 4 weeks the loss increased to 3.3 cm. The weight loss for some subjects in the first two weeks was as high as 8.4 kg while after 4 weeks some subjects lost as much as 10.1 kg in in body weight.^ As an added health bonus, subjects also displayed a dramatic decrease in LDL cholesterol, as well as a significant drop in heart rate and blood pressure. Why did isometrics work so well? It may be that the true fat-loss benefit of isometrics lies in increasing muscle size and/or density. Added muscle is active tissue which continually burns calories throughout the day—whether you are eating, working, or even sleeping (The major reason why males are generally able lose weight easier than females is due to their higher levels of muscle mass.^) This effect, plus nutritional measures, is the most effective means by which to lose body fat, not drawn-out periods of aerobic exercise. Can isometrics provide cardiovascular benefits? It is often suggested—by armchair theorists—that isometrics have little or no training effect on heart health. This is probably because it is being instinctively juxtaposed to traditional cardiovascular drills, such as running or cycling, which involve large amounts of movement. In fact, nothing could be further from the truth. The relationship between cardiac activity and isometric training has been well studied, and it is now appreciated that isometrics have a unique effect on the cardiovascular system:...both systolic and diastolic pressure markedly rise with isometric exercise in order to maintain blood flow to actively contracting skeletal muscles, thus producing a marked increase in both heart rate and mean arterial pressure. These increases are proportional to the amount of skeletal muscle that is contracting (for example, hand grip requires less increase than leg extension, which requires less than heavy weight lifting). Therefore, at any given level of oxygen uptake, vigorous isometric exercise raises heart rate, raises systemic vascular resistance, and lowers stroke volume and cardiac output more than dynamic exercise does. -Lavie, C. J. et al. (2001) Exercise and the Heart: Risks, Benefits, and Recommendations for Providing Exercise Prescriptions^1 Essentially, when you squeeze your muscles and hold that position—as in isometrics—your blood vessels become mechanically constricted by the tight muscles. As a result, the entire cardiovascular system has to work much harder to pump blood around the body. This, in turn, gives the heart and blood vessels a powerful workout. This might be termed the cardiovascular isometric response, and researchers are beginning to understand that it has major potential benefits for heart health.  The isometric response: mechanical constriction of the muscles forces the cardiovascular system to temporarily work harder—improving heart health and lowering blood pressure. A fundamental means of establishing heart health is resting heart rate (RHR).22. The stronger a heart is, the more powerfully it can pump blood around the body on a beat-per-beat basis: as a result, individuals with strong, healthy hearts tend to have a lower RHR than people with weak hearts. For example: professional athletes, with very powerful hearts, may have an RHR of just 30 beats per minute: sedentary couch potatoes can have RHRs of 80, 90, or more beats per minute.^ Studies have shown that an eight-week course of isometrics reduces the average resting heart rate by oversight beats per minute.^ Furthermore, this study only utilized handgrip training: can you imagine the improvements in heart health with total-body isometrics?  This beneficial result compares remarkably well to traditional aerobic exercise, previously considered the "gold standard" for heart health: a similar study involving a twelve-week course of aerobic exercise only reduced RHR by less than 4 beats per minute—literally half the amount achieved by isometrics.^ Zs isometrics bad for your blood pressure? As explained in the previous answer, isometrics temporarily raises your blood pressure.^ Because your muscles remain tense and contracted during isometric training—however briefly—the circulatory system in the area of those muscles becomes mechanically constricted. Just as if the pipes in any fluid system became suddenly narrower, the pressure would increase, so it is with blood pressure. After the cessation of isometrics, blood pressure quickly returns to normal. The rise in blood pressure seen in isometrics is absolutely safe for healthy individuals.^ Temporary fluctuations in blood pressure are perfectly normal, and occur as a result of all forms of exercise; and both isotonic and isometric exercise increase mean blood pressure to the same extent.^ Far from being bad for your blood pressure, several studies have indicated that isometrics training is possibly the best way to reduce blood pressure. (This is probably because the isometric response—the forcing of the blood vessels to constrict and work harder—actually strengthens the circulatory system, reducing overall blood pressure.) Whatever the biology, this effect is well-known in scientific literature.^ In one study^ individuals performing isometric exercises three times per week over eight weeks saw their systolic pressure drop by 12.5 points, and their diastolic plunge by a huge 14.9 points—that's nearly two points per week. This is a huge, potentially life-saving drop—with a low amount of training (only around twenty minutes, three times per week) in a relatively short span of time. In fact, benefits may come even quicker than that—more recent studies have noted significant blood pressure drops from as little as four weeks of isometric training.^- A comprehensive meta-analysis of the existing research, published in the Journal of Hypertension, concluded that, far from being avoided, "isometric exercise may be of value as part of lifestyle advice in maintaining a desirable blood pressure."^ Although isometric or combined isometric and dynamic (resistance) exercise has traditionally been discouraged in patients with coronary disease, it appears that resistance exercise is less hazardous than was once presumed, particularly in patients with good aerobic fitness and normal or near-normal left ventricular (LV) systolic function. Isometric exercise, regardless of the % MVC, failed to elicit angina pectoris, ischemic ST-segment depression, or threatening ventricular arrhythmias among selected (low-risk) cardiac patients. Furthermore epidemiological data indicate that regular exposure to isometric activity at the work place lowers the 5 year hypertension incidence rate by 29%...Hence it may be prescribed  as part of lifestyle modification and as an adjunct or alternative to antihypertensive therapy in maintaining a desirable blood pressure level that will help in improving quality of life and reducing the risk of cardiovascular disease. -Sandhu, et al. (2014) Scholars Journal of Applied Medical Sciences33 If you have been diagnosed with heart issues or hypertension, you should consult with your doctor before initiating an isometrics program, or any new training method. If static strength is so much greater than dynamic strength, how is it that Olympic weightlifters—who move quickly—lift heavier weights than any other athletes? Olympic weightlifting is a great sport; it develops strength, power, and flexibility as well as coordination. It is not, however, immune from the force-velocity relationship. As a result of the large weights used, it is impossible for weightlifters to achieve very high velocities, despite their acceleration during the lifts. The more weight you use, the slower you must move. When an expert weightlifter performs a snatch, for example, the velocity of the bar tops out at around 1.6 meters per second. 5^ In terms of human speed, that is not very fast: a trained boxer can punch at 14 meters per second.7^ The impressiveness of weightlifting speed relative to the weight on the bar is also misleading: the most explosive portion of an Olympic lift does not occur when the athlete lifts the heavy bar, but when he or she pulls him or herself under the bar. Can older individuals perform isometrics? Experts agree that as we approach old age, exercise ceases to become optional and increasingly becomes essential if we wish to retain functionality. ^ Strength training is of particular significance in this regard.^ Far from being something to avoid, anti-ageing researchers have predicted that, in the future, isometrics will play a significant role in keeping elderly populations safe and strong: The present results indicate that maximal isometric strength tests provide useful information about physical functional capacity among elderly people. These findings also suggest that the maintenance of adequate strength could be favourable to the mobility of older persons.  The great Norb Schemansky performs a perfect snatch. The first two photos show him pulling the weight up, relatively slowly; he then explosively pulls himself under the weight (bottom left) before standing up with it. Isometrics is the ideal form of strength training for older or elderly populations, because it is kinder on the joints, and reduces the risk of injury. Isometric training is unique, in that it boasts a complete absence of momentum; this makes it the safest form of resistance training because there are no unexpected external forces which may result in injury^: the central nervous system autoregulates its own force levels. Unlike dynamic strength, which declines dramatically with age (2.6-4.1 % per year from its peak^) isometric strength appears more loyal; with strength at age 60 only being around 15% less than at its peak during the third decade of life.^-t  In fact, far from being a drawback (as might be assumed) research shows that being older might actually be an advantage when it comes to excelling in isometric training. A comprehensive Swedish study of isometric strength and stamina in different age groups found that age did nothing to decrease endurance during static holds. This seemed to be largely because older subjects demonstrably possessed far superior pain tolerance (possibly due to accumulated life experience) than the younger athletes. This improved pain-control seemed to be progressive; the youngest subjects had the least pain control, the oldest had the best. The researchers tested 128 individuals aged from 17 to 70; the subject with the best isometric endurance was a man of 69 years of age.^ Astonishingly, isometric training may even protect older populations from Alzheimer's Disease. A recent paper in Frontiers in Aging Neuroscience strongly recommended the future exploration of isometric training for older people to preserve cognition and memory: Isometric exercise training may also play an effective role in the management of vascular risk factors at the Mild Cognitive Impairment stage of Alzheimer's Disease and may prove to be a significant strategy in the prevention, attenuation or delay of progression to Alzheimer's Disease. A plausible hypothesis is that the reactive hyperemia (i.e., blood flow) stimulated by isometric exercise training initiates a cascade of vascular, neurotrophic and neuro-endocrine events that lead to improvements in cognitive function.^ *See chapter 2.