Sports Fitness Training

Under normal physiological conditions, cells are highly efficient at maintaining steady state. However, under conditions of physiological stress, such as hypoxia (reduced oxygen supply) caused by ischemia or strenuous exercise, the energy balance can be disrupted and the functional integrity of the cell can be compromised. In these conditions, ATP concentrations fall, which leads to increases in ADP and AMP levels. In an attempt to maintain energy balance the first response of both heart and skeletal muscle cells is to break down AMP, leading to an increase in cellular IMP concentration. If ATP use continues to exceed the rate of regeneration, energy charge is further depressed. The ultimate result is catabolism of IMP to inosine and then hypoxanthine, and AMP to adenine. Hypoxanthine and adenine are lost from the cell and the concentration of total adenine nucleotides is depressed. As such, a fall in energy charge below physiological limits of the cell is prevented and it takes several days for the concentration of adenine nucleotides to return to normal.

How Women Respond to Exercise

Despite the popularity of strength training and flexibility among women in recent years, there has been little scientific study of specifically how women respond to this type of exercise. With endurance exercise, some data suggest that women use less protein for energy than men perhaps as a result of differences in fat use induced by gender-specific hormonal responses. Rodent data indicate that estradiol is protective for muscle cell membranes and, consequently, part of this response may be due to less exercise­induced damage to the muscle membrane in women. Moreover, there is some evidence that protein need with endurance exercise may even vary across the menstrual cycle Unfortunately, the effects of strength training on protein requirements in females have not been investigated extensively. Based on the observed gender differences in metabolism and the known differences in hormonal responses, it is quite possible that women respond to strength exercise somewhat differently than men. As a result, detailed study of how strength exercise training is influenced by dietary protein in women is needed.

Tags:adenine, endurance exercise, energy balance, exercise, hormonal responses, nucleotides, protein requirements, skeletal muscle cells strength training

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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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Exercise Intensity

Several early studies indicated that at least with aerobic ­type exercise, the contribution of amino acids to exercise energy production was linearly related to exercise intensity. The branched-chain amino acids (leucine, isoleucine, and valine) are the major ones oxidized and the mechanism responsible is thought to be an exercise intensity-dependent activation of the limiting enzyme (branched-chain oxoacid dehydrogenase activity) in their oxidation pathway.

Exercise Type

Apparently any increased protein need for strength exercise does not involve this exercise intensity mechanism because, despite the intense nature of this type of exercise, amino acid oxidation remains unchanged . Likely, this is a result of the large anaerobic component of strength exercise. Consequently, if body­builders need large amounts of protein it is not to provide auxiliary exercise fuel (carbohydrate provides that) but rather because sufficient amino acids must be available to maximize any increase in muscle synthetic rate produced by the exercise stimulus. Several studies indicate that there may be some truth to this commonly held beliet However, the optimal intake would appear to be 1.5-2.0 g/kg/day. This is an amount far less than what many strength athletes consume on a regular basis. Several possibilities might explain this apparent contradiction. Obviously, the athletes could be incorrect, i.e., they may have been influenced by a powerful placebo effect.

Alternatively, some other constituent in high-protein foods might, in combination with the surplus supply of amino acids, be responsible for a muscle-building effect. Several candidates are possible including creatine, a nitrogen compound found in meat and fish that has been studied recently, Although not all studies report positive effects with creatine supplementation, many demonstrate significant ergogenic effects (10% or more), especially during intense brief efforts. Such exercise-enhancing effects combined with a training program might accelerate further the normal gains observed with strength training indirectly via a super training effect. Moreover, some data exist indicating that creatine has anabolic effects on muscle, which could also playa role. Finally, although associated with a variety of adverse health effects, some compounds (i.e., anabolic steroids) are known to be anabolic 46 and it is possible that the high-protein intakes consumed by some strength athletes are only advantageous when combined with these agents.

Exercise Duration

With exercise duration, energy use from amino acids increases likely due to the decreased availability of carbohydrate as the body’s stores of this important fuel can be depleted in a single exercise bout. A similar response occurs with starvation, i.e., protein can be used for energy once the limited carbohydrate stores are exhausted. This may play some role for strength athletes if training sessions are prolonged.

Training History

In endurance exercise training, it appears that amino acid oxidation both at rest and during exercise increases perhaps due to training-induced changes in branched ­chain oxoacid dehydrogenase activity. Yet, this possibility remains controversial as the data from one study disagree and no obvious explanation to explain the discrepancy is available. The data with strength training are also somewhat unclear. It has been suggested that protein needs of novice bodybuilders might exceed those of more experienced strength trainers. Although this is consistent with the well-known observation of greater gains in muscle growth of novice strength trainers, several other studies indicate protein needs remain at similar levels for more experienced strength athletes. A recent study with acute eccentric exercise demonstrated similar increases in protein synthesis between resistance-trained and untrained subjects but that protein breakdown was greater in the latter This observation may explain why prior eccentric exercise reduces subsequent muscle damage and pain, and because eccentric exercise is part of most training programs this may indicate that the magnitude of increased protein needs induced by strength training could be reduced as one becomes more experienced. However, at this point in time, this question cannot be answered conclusively. More study of the protein needs of novice versus experienced strength trainers is definitely needed.

Tags:endurance training, exercise, exercise duration, exercise intensity, exercise training, exercise type, placebo effects strength training

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