Introduction Isometric literally means “same length”. So when it comes to resistance training, isometric refers to an exercise where the muscle produces force without changing its length. In other words you’re exerting force against a source of resistance, but there is not external movement (the muscle length and joint angle stays the same). There are several ways of utilizing this type of training, which we will see in a few minutes. But first let me explain to you some of the benefits of isometrics and why I personally like to use this type of training. Benefits of isometric exercises 1. Isometric strength; the capacity to produce force during a static muscle action, is higher than concentric (lifting) strength. In most individuals isometric strength is 10-15% higher than concentric strength (Schmidtbleicher, 1995). This high force production can be used to spark positive neural adaptations that can lead to a significant increase in strength. Remember that the more force you produce, the more high-threshold motor units you must recruit. So in that regard isometric exercises can be useful to stimulate strength and size gains. 2. In most individuals more HTMUs are recruited during a maximal isometric action than during a regular lifting movement. This is especially true in beginners. In that regard isometric exercises can be used to develop the nervous system’s capacity to recruit these HTMUs. As your CNS becomes more efficient at recruiting HTMUs during isometric actions, its overall capacity to tap into these powerful fibers will also increase; as a result you will eventually become more efficient at recruiting HTMUs in regular lifting movements. More HTMUs recruited equals more muscle growth and greater strength gains. 3. Isometrics can be used as a potentiating method. I already briefly explained what is potentiation (making a movement more efficient with a previous muscle activity). Potentiation can either be stimulated by explosive movements (which we saw earlier) and by maximal voluntary contraction. The later being called “post-tetanic potentiation”. The tetanus refers to a state of muscular activation that occurs either during a long muscular contraction (so brought on by muscular fatigue) or a very intense contraction (so brought on by a maximum contraction). The tetanus can be explained as the summation of all the available motor-units. It has been found that the force of the twitch of a muscle fiber is more important after than before the brief tetanus. This effect is present even 5 minutes after the tetanus (O'Leary et al. 1997, Gullich and Schmidtbleicher 1995). In fact, during a 7 second tetanus, the capacity to apply force decreases by 15% while this capacity is increased by 28% after 1 minute, 33% after 2 minutes and 25% after 5 minutes (O'Leary et al. 1997). So it appears that the capacity to produce force is greater 2-3 minutes after the cessation of the tetanic effort. This increase in the capacity to produce force after a certain stimulation is called posttetanic potentiation (PTP). The most effective way to promote a large PTP is to place an intense stimulation on a muscle via a maximal effort/maximal tension contraction for a length of 5-10 seconds (Brown and von Euler, 1938, Vandervoort et al. 1983). PTP can increase contraction strength, especially in fast-twitch fibers (Bowman et al. 1969, Standeart, 1964). PTP also improves the rate of force development (Abbate et al, 2000). So it can be used to potentiate both heavy lifting and explosive movements (Gullich and Schmidtbleicher 1997). PTP works by increasing the phosphorylation of the myosin light chains, which makes the actin-myosin more sensitive to calcium in the subsequent twitch (Grange et al. 1993, Palmer and Moore 1989, O'Leary et al. 1997). This is not chiefly important, but, if you wish, you can grab a physiology textbook and review the sliding filament theory of muscular contraction to see how this would increase the capacity to produce force. So to make a long story short, maximal isometrics would seem to be the best way to take advantage of the PTP phenomenon for two reasons: a) The force production is higher during an isometric action. More force produced equals greater potentiation. b) Isometric movements are less tiring than concentric/regular exercises. As a result potentiation (which improves performance) is increased while fatigue (which decreases performance) isn’t significantly elevated. The end result being a greater improvement in force production potential. To take advantage of this method you should perform a 5-10 seconds maximal isometric action (of an overcoming nature) 2-3 minutes prior to a heavy (or explosive) set of a regular exercise. This potentiating effect can be used to further increase strength, power and size gains. Later we will see what type of isometric method to use for that purpose. 4. Isometric exercises can be used to strengthen a weak point in a lift. The strength gained from isometric exercise is “angle specific” meaning that you increase strength mostly at the angle being trained (there is a 15 degrees carryover). This can both be seen as a limitation and benefit. A limitation in that to strengthen the whole range of motion you must train at least 3 joint angles per movement. But the benefit is that isometrics can be used to strengthen a specific point in a movement’s range of motion (sticking point). For example if your bench press sticking point is at the mid-range of the concentric portion, you can utilize isometric work at that specific position to strengthen that weak point without significantly increasing fatigue or increasing the required post-workout recovery time. 5. Isometric strength is important for several athletic actions. For example every movement that requires the athlete to hold a pre-determined body position (e.g. alpine skiing’s bent knees position) requires great isometric strength. Actions where there is a rapid switches from eccentric to concentric (running, changes of direction, etc.) also need isometric strength since before the switch can occur, the resistance must be stopped and that requires both eccentric and isometric strength. 6. Maximum intramuscular tension is attained for only a brief period in dynamic exercises (mostly due to the fact that the resistance has velocity and acceleration components), while in isometric exercises you can sustain that maximal tension for a longer period of time. For example, instead of maintaining maximum intramuscular tension for 0.25 to 0.5 second in the concentric portion of a dynamic movement, you may sustain it for around 3-6 seconds during an isometric exercise. Strength is greatly influenced by the total time under maximal tension. If you can add 10-20 seconds of maximal intramuscular tension per session, then you increase your potential for strength and especially size gains. As you can see properly applied isometric training can serve many purposes: it can be used to increase strength, power, muscle growth and athletic performance. Since it’s much less energy costly than regular lifting, it’s also a good way to maintain strength during a season without causing undue fatigue that might lead to a decrease in performance on the field of play. Key points 1. Isometric work can help you improve the capacity to recruit HTMUs over time, especially in beginners and individuals with an inefficient CNS. 2. Isometric exercises are characterised by a high level of force production which can be used to stimulate HTMUs into growth and strengthening. 3. You can use isometric movements to potentiate (make more effective) regular lifting exercises by performing a maximal isometric contraction lasting 5-10 seconds, 2-3 minutes prior to your regular lifting set. 4. If you have a specific weak point in a certain lift, you can rely on isometric exercises performed at that sticking point to correct the problem. 5. Isometric work is much less energy-costly than regular lifting; it won’t cause much muscle damage either. 6. Several athletic actions require isometric strength. It’s especially important for individuals participating in sports where a fixed body position is used or where frequent changes of direction are required. Types of isometric work You’ll notice that I will mention three main types of isometric exercises: overcomingisometric, yielding-isometric and functional isometrics. Understand that in the first two cases this doesn’t mean that you are combining a concentric/overcoming or eccentric/yielding action along with the isometric action. The actual external outcome of the exercise is the same; there is no movement at all. However, the intent during the exercise changes. Overcoming-isometric: You are pushing or pulling against an immovable resistance. There is no external movement, but your intent is to move the resistance (even though it’s impossible). Here you can see the three training positions for the squat in the overcoming-isometric method. Overcoming-isometrics can also be done against a manual resistance. In the example illustrated to the left coach Thibaudeau is putting bodybuilder Sebastien Cossette through a set of overcoming-isometric lateral raise. Yielding-isometric: You are holding a weight and your objective is to prevent it from moving down. So once again, there is no external movement. However, your intent is no longer to move the resistance, but to stop its movement. Below you can see three types of yielding-isometrics: a) holding a barbell, b) supporting your bodyweight plus a dumbbell and c) supporting your body weight. It is important to understand that both techniques will not have the same effect. For one thing, the neural patterns used in both cases will be different. Overcoming-isometrics may have a bigger impact on concentric strength than yielding-isometrics. Normally we use overcoming-isometrics for short sets (5-10 seconds) in order to produce a lot of force and stimulate the HTMUs as much as possible. Yielding-isometrics are utilised mostly for longer sets (20-30 seconds) and have a greater effect on size and strength-endurance than strength. A third type of isometric work can be added: functional isometrics. These are not 100% isometric in its purest sense since there is some movement involved, but for the most part it is considered an isometric method. Of all the three major methods this one is probably the most effective to stimulate strength gains. It’s also much easier to measure progress in this method that with regular overcoming-isometrics, which makes it more motivating. Functional-isometrics combine a very short range of motion concentric (lifting) action with a maximum overcoming isometric action. It requires the use of a power rack and two sets of safety pins. The bar is set between the two sets of pins (it sits on the first/bottom set of pins in the starting position) and is loaded with a heavy weight. There is 2-4” between both sets of safety pins. The exercise consists of lifting the bar off of the first set and drive it into the second set of pins. Once the bar hits the second set, you push (or pull depending on the movement) against the pins for 5-10 seconds. The differences between this type of training and the regular overcoming-isometrics are that … a) There is some concentric/lifting movement involved, even though the range of motion is fairly short. b) You add weight to the exercise. With regular overcoming isos you simply push/pull an empty bar against the pins while in the functional variation you use a loaded barbell. You keep adding weight to the bar until you reach a load that you cannot hold for 5 seconds against the second set of pins. This makes the exercise more motivating and progress easier to measure. Below is an illustration of how to set up the rack for some functional isometric work (example for the bench press). Combo isometric methods The preceding three isometric methods can be considered “pure iso methods” in that only the isometric action is emphasized. However it is also possible to combine isometric, concentric and eccentric actions in the same exercise/set. These are known as “combo methods”. Combo method 1: Single contrast - yielding In this method you include one isometric pause during the performance of the eccentric phase of a regular lifting movement. For example in the bench press you would lower the bar down to 2-3” from the chest, hold it there for 3-5 seconds, then lower it down to the chest and lift it back up to the starting position. Combo method 2: Single contrast – overcoming In this method you also include a single isometric action, but this time during the lifting phase. And you execute this pause not by simply holding the weight in place, but rather by having a partner push on the bar to stop it. When he does so, you push as hard as you can against this added source of resistance for 3-5 seconds, after which he releases the bar and let you complete the lifting movement. Combo method 3: Multiple contrast - yielding This is similar to the first method, however instead of stopping only once during the eccentric portion of the movement you stop 2-5 times (at different positions) for 3-5 seconds. Combo method 4: Max fatigue contrast In this method you perform a regular lifting set to muscle failure. When you reach that point you hold the weight for as long as you can. Depending on the type of movement you will hold the weight either at the fully contracted position or at the mid-range point. Combo method 5: Potentiation contrast This isn’t really a combo method as the isometric and concentric exercises are separated by 2-3 minutes. However since it makes use of both types of actions I still decided to include it in the combo section. In this method the isometric exercise is used to potentiate the regular lifting exercises. To do so your perform a maximum overcoming-isometric (or functional isometric) action lasting 5-10 seconds, rest for 2-3 minutes, then perform a set of regular lifting. You can either use the isometric action at the sticking point, to potentiate this specific portion of the movement so that it will become a less problematic area or perform the isometric action at the strongest point of the range of motion to have a maximal potentiation effect on the whole movement. Below is illustrated this type of training applied to the bench press. As we saw earlier, the type of exercises in which potentiating isometrics have the greatest effect are either heavy or explosive lifts. The more a movement relies on the HTMUs, the more benefits there will be from using potentiating isometrics.
When to use isometrics Many coaches believe that isometric exercises should be used at the end of a workout (Brunner and Tabachnik 1990, Vorobiev 1988). However, Siff and Verkhoshansky (1999) state that isometric action training can be used first in a workout to potentiate/facilitate subsequent strength and speed-strength exercises. I think that both options can be used: if you are using isometrics to potentiate the main exercise(s), then use it early in a workout, if you are using it to strengthen a weak point or to increase strength/size, then perform it at the end of the session. Isometrics limitations It is important to note that isometric action training still has limited applications for an athlete or bodybuilder. Yes, it can help increase strength and size. But without a concurrent dynamic (yielding and overcoming) program the gains will be slow. In other words, don’t expect huge gains if you only perform isometric exercises. Schmidtbleicher states that isometric work should comprise around 10% of the training volume when it’s used. Some coaches noted that gains from isometric exercise stops after 6-8 weeks of use (Medvedyev 1986). So while isometric action training can be very helpful to work on a weak point or improve an athlete’s capacity to activate motor-units, it should only be used for short to medium periods of time when progress has slowed down or when a rapid strength improvement is needed. Isometric action training can also be useful during periods of lowered training volumes, i.e. when one has to decrease his training load either due to fatigue symptoms or time constraints. In that context isometric work can help prevent muscle and strength losses. Key points 1. Overcoming-isometrics are more effective when used for short duration (5-10 seconds) at a maximum force of contraction. They are thus better suited to increase strength rather than size. 2. Yielding-isometrics are more effective when used for longer (20-30 seconds) periods of time. They thus better suited to increase muscle growth. 3. Functional isometrics offer the same benefits as OI but with an added motivation factor and it’s better to evaluate progress. 4. You can use isometrics at the beginning of the workout to potentiate the main exercise, or at the end of the workout if using them to correct a weak point or stimulate muscle growth. To see more about bodybuilding and training advice please follow our blog. We share Roidtest videos, Advice on Where to Buy Steroids Online, The best Bodybuilding Programs, and more.
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