Factors Affecting Strength Capacity Of Skeletal Muscle Biology Essay
Multitude of factors affects on maximum strength capacity of skeletal muscle, many of which engage in a synergistic manner. The most powerful factor is resistance training, which impressively rises maximal isometric and dynamic muscle contraction strength (Aagaard P, 2004). Resistance training is an element of conditioning and training for almost any sport. It is necessary for athletes taking part in sports who require enlarged lean body mass (LBM). The greater the mass, the greater the potential for increasing strength and power. Enlarged lean body mass is critical for increasing strength and power exhibition, improving stability, and elevating aesthetic appearance via muscle hypertrophy (Tausha 2000). Resistance training might advances various advantages to body composition, health, and quality of life (Stone, 1991). Resistance training (also named weight or strength training) is identified by the performance of exercises in which muscles from a particular body part are condensed against a power that opposes the movement (Cardoso, et al., 2010).
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As the time people commenced to participate in sports competition, nutrition has been discerned as an essential constituent of physical performance. The progression in perception of human metabolism and exercise physiology clarified in the last few decades that use of nutrient intake positively influenced sport performance, leading to an explosion of special with specific requests to exercising individuals (Molinero & Marquez, 2009). Products which claim to extend endurance, increase recovery, decrease body fat, increase muscle mass, reduce the risk of illness, or achieve other goals that improve sports performance, fill the sports world. Surveys show that athletes are main consumers of supplements and prominent target groups for the multi-billion dollar supplement industry (Burke, et al., 2000). It s easy to know why promises of enhanced performance are appealing to athletes and coaches in elite competition, where very petty differences detached the victors from the rest of the field (Hopkins, et al., 1999). However, the fame and fortune of Olympic gold medals and world records gives only part of the actuated factors find a 'magic bullet' users since even non-elite and recreational athletes are avid consumers of sports foods and supplements (Burke, et al., 2000). As a consequence, many competitive and recreational athletes have tended to dietary supplements to intensify strength training and performance. Athletes must cautiously evaluate the adequacy of their diets before starting a regimen of expensive and unproven supplements that are proposed to magnify muscular development, muscular strength, or both. Universal supplement consumption in athletes is estimated to range from 40 to 88 percent (Silver, 2001; M. Williams, 2005), more than thirty thousand supplements being commercially available in the USA (Tekin & Kravitz, 2004). Over three million people in the USA alone consume, or have consumed, ergogenic supplements (Palmer, et al., 2003), and supplement use is similarly common among athletes at high school and collegiate levels. More than 50 percent of the subjects expended $25 to 100 monthly on supplements, whereas 4.9% reported paying over $150 per month. Supplements usage could be pricey for athletes (Tausha 2000). Athletes are provided with recommendations or gossip about the advantages that are referred to supplements and sport foods. They are concerned that their contestants might have a hidden weapon, and even in the lack of strong evidence to prove a product, they may be constrained to use it to keep 'level playing field'.
Substances such as human growth hormone (hGH) and anabolic / androgenic steroids were consumed in the past and continuing to the present, in the hope of overcoming genetic limitations in hormonal status and in the ability to increase muscle. These substances have been related with several health risks and are forbidden by most athletes governing agencies.
Sports researchers are also enthusiastic in supplements and sports foods as part of their investigation for new planning to improve training and recovery, and competition performance. The applied sports nutrition research, which has helped to develop new products, is undertaken with many scientists. In addition, they explore particular methods in which they can be used to improve efficiency of performance (Burke, et al., 2000). Unfortunately, the numerous challenges to undertaking unknowing of such research denote that it is impossible to keep pace with the number of newborn products that rise on the sports market. In fact, the greater part of products are either untried or have went wrong to come up to anticipations in the initial studies that have been conducted. Scientists believe that well-controlled research must corroborate the advancement of any sports nutrition practice and are understandably thwarted that manufacturers of supplements regularly make effective claims about their products without sufficient or, in some situations, any evidence. Nevertheless, in most countries, law-making regarding supplements or sports foods is either minimal or ineffective, permitting unconfirmed claims to bloom and products to be produced with poor concurrence to labeling and composition standards. Athletes are typically unconscious of these failures.
Plants bring us most nutrients fundamental for life. More than fundamental nutrients, plant foods contain naturally occurring matters, referred to respectively as phytochemicals. Herbals, which are obtained from berries, roots, leaves, abundant, gums, stems, flowers or seeds of plants, contain numerous phytochemicals supposed to have nutritive or medicinal advantages During history, herbs have been used as medicine (Williams 2006). Herbals are modulated in various countries as medicine, such as Germany, but as dietary supplements in others. At this time, most herbals are regulated in the United States by the Dietary Supplement Health and Education Act (DSHEA), more like food components than drugs. Nonetheless, assumed the pharmacological influence of different herbals, some health specialists are accentuating the necessity for commandments standardizing herbal therapy (Sengupta , et al., 2004; Williams 2006). In the latest NHANES report, closely 7% of the US people comprising athletes obtains herbal or botanical dietary supplements (Ervin , et al., 2004). In Europe, herbal supplements represent $5 billion commerce, but France and Germany alone account for 60% of the market, proposing that utilization varies by country (De Smet, 2005). Estimations of herbal supplement usage by population of the United Kingdom differ from 10 to 25% (and are increasing), and herbal supplements presently create a £3.8 million commerce per annum (Harrison, et al., 2004; Ritchie, 2007). Likewise, consumption rates of herbal supplement in the United States have ascended sharply since the 1990s, from about 3% to about 25% of the citizens by one assay or a 380% extension by another (Bent, 2008; Bent & Ko, 2004; Senchina, et al., 2009), giving rise to o a $4.4 billion industry (Blumenthal, et al., 2006). Herbal dietary supplements are traded to physically active subjects for numerous reasons, involving augmenting energy, bringing about weight loss, promoting muscle enlargement, or inducing other physiological or metabolic responses that lead to improve exercise performance (Williams 2006). Use of herbal supplements in athletes is more common than that of the general community, ranging from 17 to 61% (Froiland, et al., 2004; Ziegler, et al., 2003). One essay found that athletes were more enthusiastic to use herbal supplements than nonathletic subjects (Senchina, et al., 2009), perhaps because many herbal supplement merchandising campaigns aim athletes with pledges of increasing performance or lessening side effects of training (Winterstein & Storrs, 2001).
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Gama oryzanol is a ferulic acid ester of sterols extracted from rice bran oil (Berger , et al., 2005). Japanese people have approved this substance for several conditions, including menopausal symptoms, stomach disorder, moderate anxiety, and high blood cholesterol. It is popularly marketed as a sports supplement in the Unites States, as well as for lowering blood cholesterol (Hoogeven & Zonderland, 1996). These profits are provided with gamma oryzanol by increasing levels of growth hormone, testosterone, and other anabolic or muscle binding hormones. Even so, there is very limited scientific proof to back up this pretension. Gamma oryzanol has been exhibited to have antioxidant properties. Consequently, it might enhance endurance and muscle building capacity by hindering the production of free radicals in muscle tissue, which theoretically could lessen muscle exhausting and fatigue in reaction to anaerobic exercise (Potricia & Rita 2004).
In fact, alterations in both neural system function and muscle structure as firmly shown in young and elderly subjects, bring about training- induced rise in maximal contractile muscle power. The effect of resistance training on muscle hypertrophy is well known. For a long time, resistance training athletes have been attracted in knowing which types of nutritional supplementation will give the greatest help in an attempt to maximize the training adaptations in response to resistance training. Speeded muscle strength increments are seen whenever resistance exercise is joined by consumption of nutritional or ergogenic supplements. Moreover, diverse banned substances and drugs may boost the build-up of muscle mass, leading to amplified gains in maximal muscle strength with training. However, some severe adverse affects arisen from banned supplements consumption are irreversible. Furthermore, IOC prohibits anabolic steroids and also they are banned in several countries by virtue of criminal making-law (Aagaard, 2004). Utilization of performance-enhancing supplements takes place at all levels of sports, from trained athletes to junior high school students. In spite of the fact that some supplements improve athletic performance, lots of them have no verified profits and lead to serious adverse effects in consumers. Resistance athletes vastly use anabolic steroids and ephedrine, which have life-threatening adverse effects, with hope of growing muscle mass and increasing performance and the International Olympic Committee and the National Collegiate Athletic Association debar them for use in contests. As a result, an attempt is made to substitute these banned drugs and supplement with effective and safe nutritional supplements. In recent years, there has been increasing interest in modeling new natural supplement without adverse side effects to avoid more irreversible problems in athletes.
Athletes consume gamma oryzanol based on preliminary studies that proposed gamma oryzanol increases muscle growth and sports performance (Fry & Kraemer, 1997), by way of rising levels of testosterone, growth hormone, and other anabolic (muscle-building) hormones. Changes of the endocrine system, including hormonal variations, change in lipid profile and so on, have been indicated to explain for the suggested performance elevating properties of gamma-oryzanol (Berger , et al., 2005). The antioxidant properties of gamma oryzanol and its derivative, ferulic acid, are promising in some areas (Potricia & Rita 2004). In athletes, macro elements in the ionized form contribute to heart and muscle contractions, oxidative phosphorylation and the synthesis and activation of enzymatic systems. Hence, equilibrating of their concentration is important for athletes. However, there are very limited essays with regards to the efficacy of such a supplementation with resistance exercise in humans, the usage of gamma oryzanol as a nutritional supplement for strength athletes is prevalent. The research to date has tended to focus on gamma oryzanol effects on patients, especially hyperlipidemia, rather than on resistance athletes. However, gamma oryzanol has been proposed to have particular properties for improving strength and efficiency of resistance training. Therefore, the aim of this clinical trial is to determine if dietary gamma oryzanol supplementation during a 9-week resistance training program will significantly alter muscular strength, lipid profile, anabolic/catabolic hormones, and anthropometric measures of young resistance athletes.
Significance of Studies:
An importance in value-added dealing with research raises, endeavors are being made to increase the value of agricultural crop by-products, comprising rice bran, through growing their pharmaceutical or nutraceutical potential. (Perretti , et al., 2003). Padi Beras Nasional Berhad reported in annual reportage 2007 that making of paddy in Malaysia reaches as much as 1.743 million metric tonnes in 2006. Rice bran is one of the derivative that is procured when it is detached from the starchy endosperm in the rice milling process (Lakkakula, et al., 2004), which represents approximately 7-8% of the total rice grain (Henderson & Perry, 1976). Fibre, proteins, oil, and effective antioxidants such as vitamin E and gamma oryzanol improve rice bran. Presently, rice bran is mainly used as animal feed (60%) and the rest (40%) is used to manufacture value added edible oil for cooking. Notwithstanding the fact that rice oil is considered nutritious oil and is going to be prevailing, particularly in USA and Europe, a huge quantity of bran nutrition was wasted along with the by-products, during rice bran oil processing.
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Additionally, Post harvest value-adding activities, at the household level within rice-growing societies, supply for innovation and spread of occupation and for income enhancement. There are demonstrated and growing choices for rice and its by-products of bran and broken rice, used for the making of food products, such as supplements. Brown rice and rice bran will become progressively merchantable as people become more aware of their health. Furthermore, other ways to improve the income of farmers is to raise the full use of the rice plant biomass. For instance, the utilizations of rice bran for gamma oryzanol supplement or oil production, etc., under the FAO-developed theory of "thriving with rice," might lead to additional income for farmers (Mew, et al., 2003).
Many strength-trained athletes, in order to assist counteract for genetic limitations in hormonal status, have consumed exogenous anabolic/androgenic steroids (AAS) impressively to increase muscle growth and strength, especially testosterone, , and many athletes suppose AAS as a principal element for success (Smith & Perry, 1992). Even so, the use of AAS has been linked to a variety of health problems and disorders. Consequently, the focus on nutrient supplementation has been expanded as a substitute to elevate muscular mass and strength (Cowart, 1992). In fact, gamma oryzanol was the first herbal derivative with examined anabolic impact as a natural substitute of synthetic anabolic steroids. Gamma oryzanol seem to be nontoxic. Negligible absorption accounts for the cause of the shortage of side effects related to higher doses (Talbott, 2003).
To study the effects of 600 mg/d gamma oryzanol supplementation on lipid profile, anabolic/catabolic hormones, circulating binding proteins and anthropometric changes in young resistance athletes during 9 weeks of intervention
To assess changes of skin fold thickness, weight, waist and hip, thigh, arm circumference, shoulder and pelvis width and BMI in 9 weeks by 600 mg/day gamma oryzanol supplementation
To assess changes of muscular strength in 9 weeks by 600 mg/day gamma oryzanol supplementation
To assess changes of blood lipid profile (TC, TG, LDL-C, HDL-C, VLDL-C) in 9 weeks by 600 mg/day gamma oryzanol supplementation
To assess changes of serum concentrations of copper, zinc, calcium and magnesium in 9 weeks by 600 mg/day gamma oryzanol supplementation
To assess changes of circulating concentrations of hormones (testosterone [free testosterone and total testosterone], dehydroepiandrosterone sulfate (DHEAS), cortisol, estradiol, growth hormone, thyroxin [T3, T4], IGF-1, insulin, thyroid stimulating hormone), adrenaline, noradrenalin in 9 weeks by 600 mg/day gamma oryzanol supplementation
To assess changes of circulating binding proteins (albumin, sex hormone binding globulin [SHBG], IGFBP3) in 9 weeks by 600 mg/day gamma oryzanol supplementation
To assess changes of ratios of free testosterone to cortisol and total testosterone to SHBG in 9 weeks by 600 mg/day gamma oryzanol supplementation
To determine relationship between changes of blood lipid profile, concentration of anabolic/ catabolic hormones, body composition and muscular strength
Skin fold thickness, weight, waist and hip, thigh, arm circumference, shoulder and pelvis width and BMI in 9 weeks will change by 600 mg/day gamma oryzanol supplementation.
Muscular strength (1RM) in 9 weeks will change by 600 mg/day gamma oryzanol supplementation.
Profile of blood lipid (TC, TG, LDL-C, HDL-C, and VLDL-C) in 9 weeks will change by 600 mg/day gamma oryzanol supplementation.
Serum concentration of copper, zinc, calcium and magnesium in 9 weeks will change by 600 mg/day gamma oryzanol supplementation.
Circulating concentrations of hormones (testosterone [free testosterone and total testosterone], dehydroepiandrosterone sulfate (DHEAS), cortisol, estradiol, growth hormone, thyroxin [T3, T4], IGF-1, insulin, thyroid stimulating hormone), adrenaline, noradrenalin in 9 weeks will change by 600 mg/day gamma oryzanol supplementation.
Circulating binding proteins (albumin, sex hormone binding globulin [SHBG], IGFBP3) in 9 weeks will change by 600 mg/day gamma oryzanol supplementation.
Ratios of free testosterone to cortisol and total testosterone to SHBG in 9 weeks will be change by 600 mg/day gamma oryzanol supplementation.
There are relationships between changes of blood lipid profile, concentration of anabolic/catabolic hormones, body composition and muscular strength.
Basic principal of resistance training:
Resistance training is an umbrella term to cover all kinds of strength or weight training and there is no need to be confused by this diversity that expresses resistance training. In fact, resistance training guides people to move further than pushing, pulling, pressing, squatting, lifting weight or if not carelessly striving with something that is weighty or hard to move. Resistance training is an inclusive expression that includes various modalities of exercise. As an illustration, any type of activity performed opposite to an extrinsic resistance, comprising plyometrics, environmental causes, sport-specific tools, physical work and specific sporting contests might enhance muscular strength, power, and/or hypertrophy. From the point of view of these various modalities, weight training, comprising barbells, dumbbells, weight machines, is most efficient for enhancing muscle mass and strength considering that it yields extreme variability while the activities performed and is easily quantifiable and monitoring and prescribing of progression can be well done (Douglas, 2001).
Possibly, the most prominent conception in weight training is "program design." Program design covers the organized handling of training variables to maximize the advantages related with weight training. When the weight training program has been appropriately planned and commenced, progression turns out to be the fundamental consideration. Therefore, the program needs to be altered for familiarizing various stimuli to the body, imposing it to adapt. Three most important concepts in weight training might be: progressive overload, specificity, and variation (Ratzin Jackson, 2001).
Progressive overload is an inclusive concept that concerns to the steady raise of the pressure imposed on the body throughout training. In fact, the human body is not under the necessity of building large and powerful muscles, except it is impelled to do so. Consequently, enhancing the forces placed on the body is predominant for progression. There are several ways in which overload can be increased during a weight training program: (1) load may be augmented; (2) repetitions may be added to the current workload; (3) repetition speed may be modified corresponding to aims, like enhanced quickness with current workload for power ameliorations; (4) rest intervals may be abridged for hypertrophy and/or increasing power; and (5) volume may be extended within plausible limits (Ratzin Jackson, 2001; Werner W K Hoeger & Hoeger, 2008; Zatsiorsky & Kraemer, 2006).
Specificity is the prime fundamental as designing resistance training programs. All training adaptations are specific for a mode of stimulus carried out. As an illustration, the physiological adaptations to training are specific to the (1) muscle actions involved; (2) speed of movement; (3) range of motion; (4) muscle groups trained; (5) energy systems involved; and (6) intensity and volume of training (Ratzin Jackson, 2001).
In addition, the principle of specificity applies to activity or sport specific development and is commonly referred to as SAID training (Specific Adaptation to Imposed Demand). The SAID principle implies that while a person is endeavoring to amend specific sport skills, the strength training exercises carried out must approach as closely as possible the movement plans encountered in that special activity or sport (Werner W K Hoeger & Hoeger, 2008).
Variation or Periodization:
Variation in training is a key factor for weight training. Variation indicates that changes in one or more of the acute program variables such as volume or intensity are systematically comprised in the plan of the weight training program. Furthermore, designed rest and recovery from training is an essential component (Ratzin Jackson, 2001). Variation is the posture of the foot, hand, and other parts of the body that do not influence in the safety of the weightlifter. Moreover, it can be employed as a training variation and affect muscle fiber recruitment patterns. Also, the application of diverse exercises to alter the conditioning stimulus of a precise muscle group is a beneficial method by which muscle fiber recruitment patterns can be altered in an effort to yield prolonged enhanced in strength and muscle hypertrophy (Fleck & Kraemer 2004).
Indubitably, for obtaining optimal growths in strength and power as training advances, periodization is required to optimize performance and recovery. Periodization makes use of variation in resistance training program design (American.College.of.Sport.Medicine, 2009; Fleck & Kraemer 2004). Hans Selye (1976) created training theory based on the biological studies of general adaptation syndrome. Systematic variation has been applied as a means of modifying training intensity and volume to make both performance and recovery. Nevertheless, the usage of periodization conceptions is not narrow to elite athletes or modern trainers, but has been used prosperously as the premise of training for individuals with different backgrounds or experiences and fitness levels. Besides sport-specific training, periodized resistance training has been exhibited to be efficient for recreational and rehabilitative training targets (American.College.of.Sport.Medicine, 2002).
Resistance exercise and endocrine system:
The endocrine system helps the normal homeostatic status of the human body and assists it reply to external stimuli. Its prominence in the scope of strength and conditioning is manifested by the essential function in the theoretical development of periodization of training (Baechle, et al., 2008). A Canadian endocrinologist, Hans Selye (1976), unintentionally presented the theoretical base of periodization with his study on the adrenal gland and the function of stress hormones in the adaptation to stress, distress and illness. Homeostatic hormonal alterations in answer to strength training have been considered to play an influential role in protein accretion, enhanced neurotransmitter synthesis, and strength improvement (Kraemer & Ratamess, 2005; Marx, et al., 2001).
Even though resistance training is the only usual stimulus that leads to gains in lean tissue mass, significant diversities are presented between resistance training program in their talent to yield increments in muscle and connective tissue size (Fleck & Kraemer 2004). The model of resistance training workout used imposes the endocrinologic and hormonal responses (Kraemer, et al., 1999; Kraemer & Ratamess, 2005; W. J. Kraemer, et al., 1993). Furthermore, tissue adaptations are affected by the modifications in circulating hormonal concentrations subsequent exercises (Baechle, et al., 2008). Consequently, considering this natural anabolic activity occurs in the athlete's body is principal to prosperous recovery, adaptation, program design, training progression, and eventually athletic performance (Fleck & Kraemer 2004; Kraemer & Ratamess, 2005).
Skeletal muscle is slightly unusual for the reason that it has multinucleated cells. This intends that the protein within a muscle fiber is regulated by numerous nuclei. Hormonal mechanisms that act reciprocally with skeletal muscle are a part of an incorporated system that intervenes the alterations made in the metabolic and cellular processes of muscle pursuant to resistance exercise and training (Baechle, et al., 2008).
Hormones are closely concerned with protein synthesis and degradation mechanisms. The formation of the contractile proteins, actin and myosin, and their extreme internalization into the sarcoma finish the process at the molecular level. A large number of hormones- comprising anabolic hormones (hormones that help tissue building as an example insulin, insulin-like growth hormones, testosterone, and growth hormones-all donate to different aspects of this procedure. As an illustration, thyroid hormones play a role as consequential allowing hormones that enable the actions of other hormones to occur. Additionally, as another important factor in the building of tissue, anabolic hormones obstruct the adverse effects on protein metabolism of catabolic hormones, like cortisol which tries to degrade cell proteins to promote glucose synthesis (Baechle, et al., 2008).
The initial hormones studied typically comprise testosterone (both total and free), human growth hormone, and cortisol (Kraemer, et al., 1999; McCall, 1999). However the acute response of these hormones has been studied comprehensively, periods of considerably enhanced volume or intensity have been indicated to bring out changes, such as decreased total testosterone, exalted cortisol, consequently, indicating these hormones to be practical markers of chronic strength training stress (Häkkinen, 1988; Izquierdo, et al., 2006; Kraemer & Ratamess, 2005; Marx, et al., 2001). Moreover, resting insulin-like growth-factor 1 (IGF-1) and its binding proteins (e.g., IGFBP-3) concentrations have been investigated and employed as markers of stress (Borst , et al., 2001; Elloumi , et al., 2005).
During and after the resistance exercise bout, hormones are secreted as a result of the physiological stress of resistance exercise (Häkkinen, 1988; Kraemer, et al., 1999; W. J. Kraemer, et al., 1993). Acute hormonal secretions give great facts to the body concerning such things as the amount and type of physiological stress like epinephrine, the metabolic requirements of the exercise like insulin, and the necessity for consequent alterations in resting metabolism. Accordingly, with particular patterns of nervous system stimulation from resistance exercise, specific hormonal modifications are concurrently activated for precise objectives associated with recovery and adaptation to the acute exercise stress. The models of stress and hormonal responses join to direct the tissue adaptive response to particular training program (Baechle, et al., 2008).
Hormonal rises in reply to resistance exercise happen in physiological circumstances that are singular to this kind of exercise stress. Eventually, the particular force made by the adaptive muscle fibers causes the change in hormone receptor sensitivity to anabolic hormones and modifications in receptor synthesis. For instance, one or two heavy resistance exercise sessions might be able to enhance the number of androgen receptors, the receptor for testosterone, in the muscle (Willoughby & Tylor, 2004). As a whole, these changes result in muscle growth and strength improvements in the perfect muscle (Baechle, et al., 2008).
Nevertheless, on the condition that the stress is too extreme, catabolic actions in the muscle possibly will surpass anabolic actions pursuant to the inability of anabolic hormones to bind to their particular receptors or the downregulation of receptors in the muscle tissue (24,110). Thus, hormonal actions are important both during and after exercise session to respond to the demands of the exercise stress (Florini, 1987). Studies have demonstrated that the volume of work, rest periods between sets, and the type of protocol are vital to the response patterns and magnitude of hormonal changes in men and women (54,119).
It appears that training intensity with loads corresponding to 80-100% of one-repetition maximum (1RM) (GonzaÂ´lez-Badillo, et al., 2005) of sufficient training volume is most effective for increasing maximal dynamic strength (GonzaÂ´lez-Badillo, et al., 2005; HaÂ¨kkinen, et al., 1987).
Strength training and stress oxidative:
It is becoming increasingly clear that a person's health and well-being are improved by physical activity as well as by a nutritious diet. Both physical activity and diet stimulate processes that, over time, alter the morphologic composition and biochemical function of the body. Physical activity and diet are interrelated in that optimal adaptation to the stress of exercise training usually requires a diet that is not lacking in various nutrients. Physical activity should therefore be viewed as providing stimuli that stress various systems of the body to various degrees and thus promote very specific and varied adaptations according to the type, intensity, and duration of exercise performed (Coyle, 2000).
Stress of physical activity:
A conceptual scheme of the stress, stimuli, and adaptation derived from physical activity in skeletal muscle is shown in Figure 1. Carbohydrate, fat, and protein, obtained either directly from daily meals or from endogenous stores in the body, provide the substrates that fuel the chemical reactions that in turn are catalyzed by enzymes and cofactors. In the process of these reactions, the chemical energy in substrates is converted to the type of chemical energy that cells can harness, namely ATP. ATP can be resynthesized anaerobically by dissolving glucose or glycogen (glycolysis) in the cytoplasm of cells, or it can be resynthesized aerobically by chemical reactions within the mitochondria that consume oxygen. These metabolic reactions proceed at the rates required to maintain ATP concentrations in the cells. Thus, increasing exercise intensity increases metabolic rate as reflected by increasing rates of chemical reactions, oxygen consumption, and substrate depletion. The resynthesis of ATP during exercise signals a disturbance in metabolic homeostasis and provides powerful stimuli to the cell that eventually cause it to adapt to exercise training, generally by altering the balance between select protein synthesis and protein degradation (Figure 1) (Coyle, 2000; Essig, 1996). In muscle, the chemical energy released by ATP hydrolysis during contraction is converted to either heat or muscle force. Muscle force develops from the tension generated by the interaction of the actin-myosin filaments and produces a mechanical loading on the muscle fibers that also provides stimuli for muscle adaptation. In this case, however, mechanical force on muscle fibers stimulates an increase in the actin-myosin mass within the muscle fiber, again by altering the balance between synthesis and degradation of these specific proteins (R. S. Williams & Neufer, 1996). This process describes the hypertrophy that occurs with weightlifting, as discussed below.
Figure 1: Theoretical scheme of the metabolic and mechanical stress on skeletal muscle during and after physical activity.
The metabolic and mechanical stresses of physical activity stimulate many healthful adaptations in numerous tissues and organs in a dose-response manner. In this context, the stress of physical activity can elicit an overall positive outcome, reflected by a reduced risk of heart disease on the one hand and increased physical performance on the other. However, physical activity can also place various tissues under acute stress. An underlying question for this journal supplement is the extent to which diet or supplementation can enhance the positive stimuli of physical activity and reduce the negative stimuli so as to optimize the healthful adaptations and improvements in physical performance (American.College.of.Sports.Medicine, 1990).
Origin and structure of gamma oryznol:
Rice has been cultivated in large part of Japan for human nutrition and as one of the export resources. In recent years, there are increasing studies focusing on the bioactive components of rice and rice bran. The starting materials for gamma-Oryzanol include seed membrane layer and germs. Naturally it is derived from rice bran oil, but it is also found in corn and barley oils, wheat bran, oats, fruits and vegetables (Potricia & Rita 2004). Generally, the substance is isolated from the crude oil obtained from these materials during the oil expression process and the intermediate so isolated is subsequently subjected to purification. The crude oil includes 1.2 to 1.8% of gamma-Oryzanol (as total ferulic acid esters). Purified gamma-Oryzanol is a white or pale yellowish crystalline powder which is practically insoluble in water. Its solubility in frequently used oils such as olive oil is around 1% under a heated condition, and it yields a precipitation with time. As an average, 0.4 to 0.6% is the practical limit of dissolution. Î³-oryzanol component of rice bran oil was first presumed to be a single component (Patel & Naik, 2004). But later it was determined to be a fraction containing ferulate (4-hydroxy-3-methoxy cinnamic acid) esters of triterpene alcohols and plant sterols (Rogers , et al., 1993). Oryzanol or Î³-oryzanol is a mixture of sterol esters of ferulic acid. This antioxidant compounds was first isolated in 1955 by Kaneko and Tsuchita. Norton (1995) reported that the complete oryzanol group is unique to rice bran oil and the exact composition of oryzanol depends on the rice cultivars. Gamma-oryzanol, a mixture of phytosteryl ferulates comprises 3 major components; cycloartenyl ferulates, 24-methylenecycloartanyl ferulate and campesteryl ferulate. Ten fractions of Î³-oryzanol isomers from crude rice bran have been successfully identified and isolated using reverse-phase HPLC (Xu & Godber, 1999). Besides the well-documented health benefits, oryzanol also has been reported as a potential additive in various food products, pharmaceuticals and cosmetics (Lloyd, et al., 2000).
Figure 2: Molecular structure of ferulic acid esterified with 24-methylene-cycloartanol (Source: Lloyd et al., 2000)
Table 1: Steroid moieties in Î³- oryzanol (connected to ferulic moiety through ester linkage)
As for the steroid moieties which are ester-linked to ferulic acid found in the structures of Î³ -Oryzanol contained in rice oil or rice bran, various steroids have been detected and identified as shown in Table -1. Generally, purified Î³ -Oryzanol involves two to four of these steroids which are chemically bound to the ferulic nucleus to from their respective conjugates.
Ferulic acid is a derivative of cinnamic acid with molecular formula C10H10O4. Ferulic acid together with dihydroferulic acid is a component of lignocelluloses, conferring cell wall rigidity by cross linking lignin and polysaccharides. It is commonly found in seeds of plant such as rice, wheat and oats. Besides, ferulic acid exhibited biochemical role in the inhibition of seed germination, inhibition of indole-acetic acid and enzyme, inhibition of decarboxylation activity and other protective effect on micro-organisms and pets.
Figure 3: Ferulic acid
Several studies in humans (Berger , et al., 2005; Most, et al., 2005) and animals (Purushothama , et al., 1995) have established that the ingestion of a rice bran oil (RBO) diet reduces serum cholesterol and triglycerides. From the results of human and animal studies, researchers speculated that the hypocholesterolemic effect of RBO is attributed to its specific components, gamma-oryzanol and gamma-tocotrienol. The major components of gamma-oryzanol were identified as ferulic acid esters of triterpene and phytosterols (Fang , et al., 2003). Gamma-Oryzanol was shown to decrease plasma cholesterol in rats (Purushothama , et al., 1995). An amount of gamma-oryzanol > 0.2% (weight percent of the diet) decreased serum and liver cholesterol levels in hypercholesterolemic rats induced by additional dietary cholesterol. The mechanism of the hypocholesterolemic effect of RBO and gamma-oryzanol is through decreasing cholesterol absorption in the intestines and increasing fecal cholesterol excretion .
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