Sports Fitness Training

Another mechanism involved in the generation of free radicals in weight trainers does not involve the physiological effects of training, but involves the effects of recovery from training, namely, free radical production in damaged muscle. As a result of intense resistance exercise, the skeletal muscle of bodybuilders, power lifters, and Olympic lifters is subjected to both mechanical and oxidative damage. This damage includes the loss of sarcoplasmic reticulum structural integrity, increased lipid peroxidation and membrane perturbations, and the release of both myoglobin and muscle enzymes into circulation. Exercise ­induced muscle damage can occur from both concentric and eccentric training, but eccentric contractions, or negatives, are known to cause greater structural damage and thereby increased oxidative damage. Oxidative stress in resistance training does not come from a dramatically elevated metabolic rate during the exercise bout as in aerobic trainers, but is actually part of the repair process. After muscle damage, including exercise-induced micro trauma, there is a period of neutrophil and monocyte/macrophage infiltration. The white blood cells (leukocytes) that are activated in response to muscle damage are mobilized to the damaged area in an attempt to initiate repair. Delayed-onset muscle soreness has been related to this repair process. Although this immune response appears to be proportional to z-band damage, even moderate exercise has been shown to trigger a two­fold increase in neutrophil activation. As a consequence of neutrophil activation, these repair processes are well known to use oxygen radicals as a means of clearing away microscopic tissue fragments. Again, in this scenario, the healing of damaged muscle can lead to further muscle damage due to oxidative stressors brought on by the repair process. In addition to white blood cell infiltration, cell damage can lead to both muscle calcium abnormalities and the disruption of iron - containing proteins, including myoglobin. One concluding note is necessary to put the concepts of exercise, radical production, and muscle damage into perspective. Although the research is not clear-cut when approaching the question of which came first, the radicals or the damage, it can be speculated that exercise causes a downward spiral situation. Acute bouts of aerobic and resistance exercise both cause increased free radical production, although through different mechanisms (oxygen processing and reperfusion injury). Since these free radicals are known to cause damage to cytoskeletons, membranes, and other cellular components, it can be concluded that post-exercise muscle damage is due, in part, to free radical actions. Once skeletal muscle is damaged, however, leukocyte radical production is initiated to clear away damaged fibers, leading to the subsequent release of more free radicals and further damage. Further research is required to quantify the nature of each step’s contribution to the oxidative damage seen is skeletal muscle.

Tags:delayed onset muscle soreness, Injuries, muscle damage, muscle enzymes, myoglobin, oxidative damage, oxygen radicals, power lifters, resistance exercise, sarcoplasmic reticulum weight trainers

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Excess protein has been considered by many nutritional experts to be hazardous to the health of athletes. According to research from the Medlantic Research Foundation, “Protein intake is more than adequate in the USA and further increases could have negative effects on the prevalence of renal disease and osteoporosis.” Certainly, there is little evidence in active, athletic individuals that high-protein consumption is harmful to one’s health.Because of the kidney’s role in processing and ridding the body of nitrogenous waste, this organ could be particularly susceptible to damage from being overworked. Theoretically, large amounts of nitrogen from a high-protein diet may become toxic. Despite its role in nitrogen excretion, there are presently no data in the peer-reviewed scientific literature demonstrating the normal kidney will be damaged by the increased demands of protein consumed in quantities above the RDA. Furthermore,real world examples support this contention as kidney problems are nonexistent in the body­building community in which high-protein has been the norm for over half a century.

Researchers Poortmans and Dellalieux from the Department of Physiological Chemistry, Institute of Physical Education and Kinesiotherapy at Free University in Brussels, Belgium, studied the effects of a high- and medium-protein intake in bodybuilders and other well-trained athletes. Subjects underwent blood and urine sampling in addition to keeping a 7-day record of their food intake. Data demonstrated that despite higher plasma concentrations of uric acid and calcium, the group of bodybuilders on the high-protein diet had normal renal clearance of creatinine, urea, and albumin. Interestingly, the nitrogen balance for both groups became positive when daily protein intake exceeded 1.26 g/kg. Researchers concluded that protein intake under 2.8 g/kg/ day does not impair renal function in well-trained athletes.

Animal data enforce the belief that a high-protein diet does not damage the mammalian kidney. This lack of toxicity is present even at extremely high amounts for prolonged periods of time. Zaragoza and colleagues fed rats a dietary regimen in which protein constituted 80% of their energy intake for more than half of their life span. In spite of the amount of protein and the time of administration, no deleterious effects were noted.

High-protein diets may increase the excretion of calcium, a particular concern to women at risk for osteoporosis. However, work by Orwell and Porter & Johnson suggest that increased protein intake is often beneficial and associated with anabolic processes in bone. In a study published in Calcified Tissue International, Cooper et al. studied bone density (dual-photon absorptiometry in the lumbar spine and proximal femur and single-photon absorptiometry in the distal and mid-radius) in 290 women ranging from 30 to 94 years of age. Dietary information on calcium, phosphorus, vitamin D, protein, fat, and total energy were obtained from a 7-day food record. Among the premenopausal women studied, there was a statistically significant positive association between protein intake and bone mineral content in the distal radius and proximal femur. Postmenopausal women showed no relationship between protein and bone mineral content. From the food record, all of the women studied consumed a mean of 75 g/day of protein.These results suggest that dietary protein consumption may be a determinant of the peak bone mass attained by premenopausal white women. They further commented that the finding of a positive association between protein consumption and bone mineral content was a surprise because animal and human studies on calcium metabolism show excess urinary excretion of the mineral as protein intake increases. According to work by Freudenheim et al., it is possible that the hypercalciuric effect of protein is offset by a hypocalciuric effect of phosphorus, which is present in substantial quantities in diets high in meat protein. In women who engage in strength training, any hypercalciuric effect of protein may be offset by the strong effect this mode of exercise has on increasing bone density. There may be further benefits on bone from a high-protein diet and weight training via increased insulin-like growth factor-1, which has been shown to have a positive effect on bone mass. Levels of this peptide hormone have been shown to increase in strength-trained subjects after a protein-carbohydrate supplement and in those who consume a protein supplement after hip fracture.

Atherogenic effects of high-protein diets have been over­ stated, especially in regards to athletic populations. In the past, strength athletes and football players (especially offensive and defensive linemen) were known for consuming protein sources that were high in saturated fat such as various forms of fast food, whole milk, and fatty cuts of beef. Today, athletes have access to protein sources that contain minimal amounts of fat like chicken breast without skin, fish, lean cuts of beef, and egg whites. Protein supplements available today contain little to no fat. To consider a diet high in protein that is also high in fat is an outdated concept. With the variety of lean, whole-food sources of protein and the multitude of protein supplements available, some athletes may need to be advised to consume additional fat in an effort to get sufficient calories to meet their daily requirement.

Tags:athletes, bodybuilders, excess protein, high protein diet, kidney problems, nitrogen excretion, nutritional experts, osteoporosis, protein intake Supplements

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One of the characteristics of competitive sport that distinguishes it from other forms of physical activity is the importance of winning. Indeed, in many countries 2nd place is referred to as the first loser. In this context an athlete purposefully chooses to strive for performance excellence. It is likely that a large part of the emphasis on winning and excellence of performance stems from an intrinsic motivating factor (i.e., some people simply hate to lose). Other extrinsic factors can also play a major role. For example, sports fans prefer and even expect their teams to be winners regardless of the competitive level. Some countries, both past and present, have used sport as a political tool often to the detriment of sport (e.g., Soviet Union’s boycott of the 1984 Summer Olympics in Los Angeles). Because of these factors even amateur sport with its myriad of governing bodies has become a big business with high stakes for those involved. Thus, because of both intrinsic and extrinsic factors it is incumbent upon the athlete to be a winner.

Hypocrisy Regarding Drug Testing

The International Olympic Committee’s policy on doping has been instituted partly to protect the athlete’s health, however, high-level athletic competition is often an inherently unhealthy endeavor. If health is a factor then why are certain sports with high injury rates or the potential for serious injury allowed at all? For example, many linemen playing American football weigh over 135 kg. These higher body weights are necessary to be successful at this sport; however, gaining large amounts of weight is unhealthy.

False Positives

Certain drugs such as cocaine are not found naturally occurring in humans. Thus, detection of these substances is relatively easy. Many hormones, when used as ergogenic aids, are quite difficult to detect (e.g., growth hormone). Also, certain androgens have been recently shown to occur naturally (i.e., nandrolone); thus, cutoff limits for drug testing must be established.

Flawed Process?

In the process of drug testing, two samples of urine are collected and stored. If a positive test occurs for sample A, the NGB and the athlete are notified. The athlete or their representative can observe sample B being tested. If both samples are positive, the test results are subsequently made public. The athlete has a right to arbitration (i.e., a trial). In many sports there are two trials. First is the trial within the athletes’ governing body and then there can be a trial within the international body. This system then places the athlete and their NGB in adversarial roles. For example, in track and field the International Athletics Federation (IAAF) is the international governing body. First the athlete must go through arbitration within their NGB (UK Athletics or USA Track and Field, for example). The results of this trial are then forwarded to the IAAF Rarely, if ever, does the lAAF accept an NGB arbitration verdict that the athlete was innocent of doping (e.g., Dennis Mitchell and Dougie Walker). The stated position of the lAAF is that the athlete is guilty until proven innocent and that it does not matter how the substance got there (Athlete guilty until proven innocent Doug Gillon, August 20, 1999, The Electronic Herald). Thus, the second trial begins with the IAAF Rarely, if ever, do the athletes prove themselves not guilty to the lAAF (e.g., Dennis Mitchell and Dougie Walker). A number of reasons can be given for a false positive including individual differences in metabolism, taking a legal supplement that contains a banned (or the building blocks) substance, and sabotage (e.g., Tonya Harding). None of these reasons are sufficient in the eyes of the IOC/IAAF.

What is unfortunate is that after the myriad of legal maneuvers, the athlete’s reputation can be damaged and a considerable amount of time, money, and effort are spent. The athlete (e.g., Diane Modahl) might win the lawsuit and then the NGB loses a great deal of money; however, the lAAF and IOC have so far been protected. Even when a national court finds in favor of an athlete (e.g., Butch Reynolds) the IOC/IAAF, etc. may not meet their obligations openly or fairly.

Facts

There are clearly problems with doping tests. Pointing out these problems is not a blanket indictment of doping control but rather an attempt to identify deficienciesThere is little doubt that ergogenic aids will continue to be used, as will banned substances until adequate testing methods can be devised. Perhaps the vast majority of athletes would not use banned substances if they believed that the playing field was level. Certainly, the current testing methods do not work well. Consider the following:

1. The IOC testing procedures should be reviewed by independent agencies. The IOC should release data on athletic testing (especially for nandrolone) to independent agencies for evaluation and validation.
2. Until adequate tests can be devised for testosterone, it should be removed from the banned list.
3. An independent agency should take over doping control that will remove suspicion from the athletic governing bodies and eliminate the current adversarial role of the national and international governing bodies.

Tags:amateur sport, androgens, athlete, athletic competition, body weights, drug testing, ergogenic aids, false positives, nandrolone Sports Controversies

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Caffeine, a central nervous system stimulant, is one of the most widely used drugs in the world. This substance may improve alertness, concentration, reaction time, and energy levels. In addition, its effect on promoting lipolysis has been touted as a mechanism by which it acts as an endurance ergogenic aid.

Human Studies

One of the first studies conducted on the effects of caffeine and endurance was by Perkins and Williams in 1975 Resting heart rate, submaximal heart rate, maximal heart rate, and ratings of perceived exertion were tested in female subjects before and after a progressive workload to exhaustion on a cycle ergometer. The subjects ingested a placebo, or 4 mg, 7 mg, or 10 mg of caffeine in this double-blind study. There was no significant effect on exercise performance.

Another early study on caffeine was conducted by Costill et al. Nine competitive cyclists exercised until exhaustion on a cycle ergometer at 80% . One trial was conducted 1 hour after the ingestion of decaffeinated coffee and the other after the ingestion of coffee containing 330 mg of caffeine. The trial with caffeine resulted in a longer cycling time compared with the trial without caffeine . Fat oxidation was significantly higher with the use of caffeine and ratings of perceived exertion were significantly lower. The authors concluded that caffeine increased endurance by increasing lipolysis and exerting a positive influence on nerve impulse transmission.

Ivy et al also conducted a study on caffeine and its effects on endurance in the late 1970s. Nine trained cyclists were used in this study The subjects ingested 250 mg of caffeine 1 hour before a 2-hour bout of isokinetic cycling at 80 rpm. The subjects also ingested an additional 250 mg of caffeine at 15-minute intervals during the first 90 minutes of exercise. This significantly increased work production and VO2 by 7.4% and 7.3%, respectively Fat oxidation was also elevated by 31%, therefore, the increase in work production with the ingestion of caffeine was attributed to an enhanced rate of lipid catabolism.

In a recent study by Cohen et al seven competitive road racers performed three, 21-km races in the heat and humidity after randomly ingesting 0, 5, or 9 mg/kg of caffeine. The subjects were allowed to imbibe water at each 5-km interval. They found no improvement in race times for any of the caffeine doses when compared with a placebo.

A study by Wemple et al. also showed no improvements with the use of caffeine. Six subjects performed 3 hours of cycling at 60% . Also, maximal performance was tested at 85% following the 3-hour endurance trial. During exercise, the subjects ingested 35 mL of a carbohydrate electrolyte drink with or without 25 mg/dL of caffeine. At rest, the urinary volume was significantly greater during the caffeine trial (1843 mL) versus the placebo (0411 mL), but during exercise there was no difference in urinary volume (398 versus 490 mL for caffeine and placebo, respectively). Conclusively, this study showed no improvement in endurance performance; however, this study also showed that there is not a risk of dehydration with the ingestion of 25 mg/dL of caffeine.

Conversely, most studies conducted on the use of caffeine have shown positive results on endurance performance. Immediately before exercise, six endurance-trained males, who had previously competed in at least two marathons, ingested 10 mg/kg of caffeine or a placebo? The exercise consisted of running on a treadmill at 75% of their VO2max for 45 minutes, and then increasing the speed by two miles per hour until exhaustion. The caffeine trial resulted in a significant increase in the distance run when compared with the placebo 0.9% increase and control (2.1% increase).

Different dosages of caffeine (0, 5, 9, or 13 mg/kg) were also investigated in nine well-trained cyclists 8 Encapsulated caffeine was administered 1 hour before the subjects cycled at SO% VO2max until exhaustion. A significant increase in endurance performance was noted during all three trials when compared with the placebo but there was not a dose­related response. Also, there was an increase in free fatty acid and glycerol concentrations with the ingestion of caffeine.

The effects of caffeine were investigated at different levels of intensity. Eight untrained males cycled until exhaustion at 10% above or below anaerobic threshold after randomly receiving 5 mg/kg of caffeine or a placebo 60 minutes before exercise. There were no differences between trials when the subjects exercised at 10% above anaerobic threshold; however, ratings of perceived exertion were significantly lower (14.1 versus 16.6 for caffeine and placebo, respectively) and time to exhaustion was significantly higher during the caffeine trial at 10% below anaerobic threshold. This may be because the subjects were untrained.

A study was also conducted on the effects of caffeine in coffee or water. Nine fit, young adults performed five trials after ingesting a capsule of caffeine or placebo with water or coffee (decaffeinated coffee, decaffeinated coffee with caffeine added, or regular coffee). The dosage of caffeine was 4.45 mg/kg with 7.15 mL/kg of solution. After 1 hour of rest, the subjects ran at 85% until exhaustion. Plasma epinephrine was significantly increased with the ingestion of caffeine, and the increase was significantly greater with the capsules when compared with the coffee. Also, endurance performance was only increased during the caffeine capsule trial (7.5- to 10-min increase when compared with the other four trials). The authors speculated that coffee must have a component that moderates the actions of caffeine.

Bell and Jacobs conducted one of the most recent studies done on caffeine. In this field study; nine healthy male recreational runners completed six 3.2-km runs wearing 11 kg of gear (Canadian Forces Warrior Test) after ingesting 325 mg of caffeine and 75 mg of ephedrine. Heart rate was significantly higher in the caffeine and ephedrine trials, and supplementation significantly improved the subjects’ time when compared with a control and placebo trial .

The plethora of data clearly show that there are potential benefits of consuming caffeine before an endurance event. This central nervous system stimulator can increase the release of catecholamines and increase the use of free fatty acids for energy. Dosages as low as 330 mg 1 hour before exercise have been shown to increase an individual’s performance time.

Safety and Toxicity

Moderate to high doses of caffeine can result in nervousness, restlessness, insomnia, and tremors. Caffeine is also a diuretic, which might increase the risk of dehydration and heat-related illness. Caffeine can be addictive and result in severe headaches, fatigue, irritability, and gastrointestinal distress after withdrawal from the substance. In addition, individual differences in caffeine sensitivity may account for the lack of an ergogenic effect.

Also, regarding competitive sports, the International Olympic Committee only permits 12 µg/mL of caffeine in the urine. This is the equivalent of consuming 600 to 800 mg of caffeine within 30 minutes .

Tags:carbohydrates, Diet and Training, endurance performance, exercise, glycerol, herbal supplement, sodium bicarbonate Supplements

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It is well known that intense or prolonged exercise results in oxidative injury to skeletal muscles, particularly in untrained individuals. Further, there is growing evidence that radicals and other reactive oxygen species contribute to muscular fatigue. Therefore, it is not surprising that there is strong interest in the effects of antioxidant supplements on exercise performance. Numerous animal studies have examined the effects of antioxidants on muscular performance. Many of these experiments have used in vitro preparations in which antioxidants were added to the bathing medium surrounding the muscle. In general, these in vitro experiments indicate that the addition of antioxidants results in delayed muscular fatigue. Some in vivo animal studies also indicate that the addition of antioxidants can improve muscular performance. Collectively, these experiments suggest that antioxidant supplementation can improve muscular performance by reducing exercise-induced oxidative stress. Nonetheless, most animal studies have used antioxidant treatments that cannot be used in humans. Therefore, results from antioxidant research using animal models cannot always be directly extrapolated to humans.Research examining the effects of antioxidant supplementation on human performance is in its infancy. At present, limited studies have examined the effects of antioxidant supplementation on muscular endurance in humans. Further, many of the studies suffer experimental design weaknesses and most studies have investigated the effects of a single antioxidant rather than investigating the combined effects of both lipid and water-soluble antioxidants. By far, the most widely studied antioxidant vitamin is vitamin E, whereas few studies have examined the effects of other antioxidants on human performance. Although several human studies have indicated that supplementation with vitamin E and/or vitamin C reduce exercise-induced oxidative stress, there is limited evidence that antioxidant supplementation can improve human performance. However, because of the paucity of research on this topic, many additional studies are required before a firm conclusion can be reached about the effects of antioxidant treatment on human exercise tolerance.

Future studies should examine the potential synergistic effects of several antioxidants on human performance. Further, additional experiments are required to explore the bioavailability of nutritional antioxidants provided in tablet form compared to the bioavailability of these nutrients derived from whole food. This is an interesting area for future research.

Tags:Diet and Training

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Of course, the majority of people who train with weights are never going to compete (just as most people who play tennis or golf don’t expect to enter Wimbledon or the Masters Invitational). But whether you bodybuild with the aim of sculpting a competition physique or are training to improve your performance at sports, to be healthy and fit, to look and feel better, or to rehabilitate an injury, all muscle building done correctly depends for its results on the same basic exercise principle, that of progressive-resistance training.Progressive-resistance training works because the body is designed to adapt and grow stronger in response to greater amounts of stress than it is used to. If you are used to running two miles a day, then running five miles puts more demand on your muscles and the ability of your cardiovascular system to supply enough oxygen and nutrients to keep the muscles functioning under the stress of this greater demand. You may be in shape to run two miles, but you have to get in better shape to run five miles. Improving your conditioning in this case is a matter of increasing how far you run and giving the body time to change and adapt to this increase.

When it comes to muscle building the same principle applies. The muscles are adapted to dealing with a certain level of demand, specifically to a certain amount of weight in your exercises lifted with a certain degree of intensity. When you increase the amount of weight and/or intensity, your muscles have to become bigger and stronger to deal with it. Once they have adapted to the new level of demand, you increase the amount of weight and/or intensity in your workouts so that they will continue to get bigger and stronger. In other words, you progressively increase the demands you make on your muscles over time.

But not every kind of training you do with weights is going to end up creating a bodybuilding physique. You have to do the right kind of exercises, using the right techniques, so that you send a specific message to the nervous system that tells the body what kind of adaptation you wish to achieve. This is called specificity of training and it is why learning how to train the right way is so important.

Bodybuilding is based on that same principle. The body doesn’t

know what you think you are telling it to do, it only registers and adapts to the specific instructions you are giving it by the way you are working out. You may feel you are building muscle, you can be working hard, sweating, getting tired and sore, but unless you are sending the right code to the body, you are going to be disappointed in your results. And the code in this case is a correct understanding of the principles of progressive-resistance training.

Tags:bodybuild, cardiovascular system, muscle building, muscles, physique, resistance training, stress workouts

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The phenomenon of overreaching and overtraining is not new to sport. Athletes involved in intense training often experience short-term and/or long-term decrements in performance. In fact, coaches and athletes often plan intensified periods of training in hopes that the training will promote greater training adaptations. Unfortunately, while some athletes respond well to the intensified training, others may become overreached and/or over­trained. According to Kreider, overreaching is an accumulation of training and/or nontraining stress resulting in a short-term decrement in performance capacity with or without related physiological and psychological signs and symptoms of overtraining in which restoration of performance capacity may take from several days to several weeks. More severely, overtraining is an accumulation of training and/or non training stress resulting in a long­term decrement in performance capacity with or without related physiological and psychological signs and symptoms of overtraining in which restoration of performance capacity may take several weeks or months.Although the specific etiology of overtraining is unclear, there are basically two types of overtraining described in the literature-sympathetic and parasympathetic . Sympathetic overtraining is typically associated with anaerobic strength-power training whereas parasympathetic overtraining is usually associated with endurance exercise training. In sympathetic-type over­training, performance is decreased and response to training stimulus is delayed. Athletes may also exhibit signs/ symptoms of increased irritability; disturbed patterns of sleep, weight loss, increased resting heart rate and blood pressure, and/or impaired recovery during training. In parasympathetic-type overtraining, performance capacity is decreased and response to training is also delayed with decreases in heart rate, blood pressure, and suppressed neuromuscular excitability. Other factors that can result in a decrease in performance are fatigue, depression, and altered endocrine function.

Although some overreached/overtrained athletes experience a decrease in performance without any signs/symptoms of overtraining, most will exhibit some of these overt signs. However, there does not appear to be any consistent pattern of symptoms of overtraining among athletes. Therefore, although some markers have been proposed, there are presently no valid markers of overreaching and overtraining other than reductions in exercise capacity.

Several factors have been suggested to increase the susceptibility of athletes to become overtrained. Care should be taken to plan training carefully so that the athletes are progressing properly from various training phases to avoid sudden increases in training volume and/or intensity. Care should also be taken to ensure that there is enough recovery time during training to optimize physiological adaptations. Additionally, one must consider that the athlete not only must endure the physical stress of training but that the psychological stress of competition, school, work, social environment, or personal life may add to the physical stress of training. 6 Coaches and trainers should be aware of these psychological stressors and alter training volume and intensity as necessary.

It is also clear that during periods of increased physical or psychological stress, athletes often do not eat enough calories to offset energy expenditure. The result is that the athlete maintains a negative energy status that may further compromise training adaptations. Consequently, coaches and trainers should ensure that the athlete is well-fed during periods of intensified training. Finally, it is recommended that coaches and athletes closely monitor signs and symptoms of overtraining during training. Research has indicated that some psychological signs (e.g., general fatigue, lethargy, disinterest in training, etc.) may often precede physiological symptoms of overreaching/ overtraining. Therefore, simply monitoring how athletes feel, how they perceive they are responding to training, and performance markers can serve as valuable feedback in understanding how athletes are tolerating training so that training volumelintensity can be altered accordingly.

Tags:blood pressure, Diet and Training, endurance exercise, exercise training, intense training, psychological signs, resting heart rate, sport athletes, stress, sympathetic and parasympathetic, symptoms of overtraining Uncategorized

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Static Exercise

Isometric contractions are usually held for 6 to 10 seconds and require a minimum exertion of two thirds maximum force. Maximum exertions produce greater results than sub-maximum efforts. A total contraction time of 30 seconds of applied force is desirable. This can be achieved by two or three confections of long duration or more contractions of shorter duration for each muscle exercised.

Isometric exercises are effective for developing strength, but this approach has some important limiations. The most serious of these is a higher than expected rise in exercise arterial blood pressure and an increased workload on the heart throughout the entire contraction. All-out straining isometric contractions should not be performed by individuals with heart and vascular disease. A second limitation is that strength developed isometrically is joint­angle specific. Maximum strength development occurs at the angle of contraction, with a training carryover of approximately 20 degrees in either direction from that angle. To develop strength throughout the muscle’s range of motion, you must perform isometric contractions at several different points in the range of motion.

Because muscles cannot overcome the resistance in isometric training, measuring improvement is difficult, constituting another limitation of this system. Improvements in strength can be measured if exercisers have access to specialized equipment, such as dynamometers and tensiometers, that record the amount of force applied. Motivation for exercise is difficult to sustain without feedback.

Research indicates that isometric exercise systems are as effective as dynamic exercise systems for developing strength. The question is not which system is better but which system best satisfies the intended use for the newly acquired strength. The transferability of strength to occupational and leisure pursuits is very relevant.

Strength developed in the muscles is highly specific to the manner in which the muscles are trained .muscles trained isometrically perform best when stressed isometrically; muscles trained dynamically perform best when stressed dynamically. There is some transfer of isometric training to everyday life. Carrying groceries, a baby, or any object in a fixed position or pushing and pulling objects requires isometric strength, but most movements are dynamic, md transfer is more widely applicable from dynamic systems of training.

Dynamic Exercise

Dynamic exercises include isotonic (equal tension), variable resistance, free weights, and isokinetic (equal speed).

Isotonic Training

Isotonic exercise training systems use both concentric and eccentric contractions as the exercising muscle shortens and lengthens about a joint. Both types of contractions contribute to the development of strength.

Variable Resistance Training

Variable resistance exercise equipment was developed in response to isotonic exercises not maximally stressing muscles throughout their full range of motion. The maximum weight lifted isotonically is limited to the weakest point in the musculoskeletal leverage system. The weight appears lighter at some points in the joint movement and heavier at others. In reality, the weight itself is constant and the human bony leverage system changes.

Free-Weight Training

Isotonic training with free weights (dumbbells and barbells) continues to be an appropriate method for strength development. Free-weight training provides many advantages. For athletes, it yields some flexibility in strength development because the movements are not confined to a track. Exercises can be selected or improvised to simulate the movements required by specific sports, allowing the development of the muscles that will be used in competition. Concurrently, ancillary musculature that plays a supporting or stabilizing role for the major muscles is also stimulated and developed.

Circuit Resistance Training

Circuit resistance training (CRT) is very effective for individuals who wish to develop several fitness dimensions simultaneously. Muscular strength and endurance, changes in body composition, and improvement in cardiorespiratory endurance can be attained together.

Tags:arterial blood pressure, dynamic exercise, dynamometers, exercise, exercise systems, isometric exercise, isometric training, static exercise strength development

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