Principles of Conditioning
This article addresses the principles of conditioning and how these fundamental principles can be appropriately incorporated into school-based physical education. The components of health-related fitness discussed in the overview are muscular strength, muscular endurance, and aerobic endurance as conditioning principles directly apply to each of these components. The principle of overload and the FITT principles are discussed as they relate to resistance training, which develops muscular strength and muscular endurance, and aerobic conditioning, which develops aerobic endurance. Physical education teachers must follow several guidelines and consider teaching strategies when designing developmentally appropriate resistance training and aerobic conditioning programs for their students. Perhaps most important, teachers must understand that their role in students' physical fitness development is to educate students about how to make healthy choices as they relate to their level of physical activity in an effort to decrease the rate of childhood obesity and diseases related to sedentary lifestyle.
Keywords Aerobic/Cardio-Respiratory Endurance; FITT Principle; Health-Related Fitness; Hypertrophy; Muscular Strength; Overload; Physical Fitness; Resistance Training; Skill-Related Fitness; Target Heart Rate Zone
Principles of conditioning are those tenets of exercise science that address the physiological processes by which individuals improve their muscular strength, muscular endurance, aerobic and anaerobic capacity, and flexibility. The scientific theories and tenets that these principles are based upon are addressed in the fields of exercise and muscle physiology. For the purpose of this article, the specific physiological processes that occur during physical activity will not be discussed; rather the focus will be to provide a synopsis of the principles of conditioning based on how they are relevant to physical education. Principles of conditioning, within the context of physical education, involve the application of physiological principles to the learning objectives and teaching methods that are employed in the classroom in order to design activities and curricula in a manner to enhance the students' level of physical fitness and knowledge and understanding of conditioning concepts.
The National Association for Sport and Physical Education (NASPE) has set forth recommended content standards for teaching and learning in physical education (NASPE, 2007). The six national standards provide a framework to guide state and local school administration in the development of physical education curricula and also demonstrate the purpose of physical education and its academic merit and value as a component of education (NASPE, 2007). The third and the fourth standards state that students should engage in regular physical activity and demonstrate or achieve and maintain a level of physical fitness that enhances health (NASPE, 2007). With the number of obese and overweight youth having increased dramatically over the last few decades, it has become increasingly important for physical educators to focus on achieving these standards by incorporating physical activity and health-related fitness education into the physical education curriculum (Greer & Gilbert, 2006). A 2010 position statement by NASPE, "Appropriate Uses of Fitness Measurement," affirms these standards and the NASPE's position that fitness measurement should be used to improve student health and physical activity programs, and should focus on the process of achieving fitness rather focusing on individual achieved outcomes to assign student grades or teacher effectiveness ratings. Physical education can also play an important role in a student?s general education, addressing measures such as problem-solving and personal growth, as argued by Thorburn and MacAllister (2013).
Physical fitness is defined as the ability to perform physical activity (Casperson, Powell, & Christenson, 1985). Health-related fitness is a term that is used to indicate physical activity that aims to promote good health and wellness as opposed to conditioning that is specifically designed with performance as the focus. Performance-focused training is called skill-related fitness and focuses on the development of speed, power, reaction time, balance, coordination and agility, which are related to enhancing performance and/or sport skill development (Corbin, 2004). Health-related fitness, which is applicable to the physical education setting, encompasses five components: 1) muscular strength, 2) muscular endurance, 3) aerobic endurance, 4) flexibility, and 5) body composition (Maina, Griffin, Ryan, & Schlegel Maina, 2001).
Muscular strength, muscular endurance, and aerobic endurance are the health-related fitness components that are directly related to physical conditioning in the physical education setting. Muscular strength is defined as the force that a muscle can produce or exert in a one time maximal effort or the greatest amount of weight or resistance a muscle can move or lift for one repetition only, also known as a "one rep max" (Maina et al., 2001). Muscular endurance is defined as the ability for a muscle group to perform, or contract, repeatedly at a resistance below the maximum resistance that the muscle can move (Maina et al., 2001). Aerobic endurance is defined as the body's ability to engage in activity over a prolonged period of time and utilizes oxygen in the process of energy generation (Universal Fitness Tester, 2007).
Resistance training, or weight training, is a mode of exercise that aims to increase muscular strength and endurance through the process of overloading the muscles. The conditioning principle of overload requires that the body must undergo a level of stress that is greater than the norm in order for the body to undergo physiological adaptations that increase muscular strength and endurance. Resistance training as a form of conditioning for youth has been investigated to determine whether or not this type of exercise is appropriate for children and adolescents and what benefits result (Kraemer, Fry, Frykman, Conroy, & Hoffman, 1989). Research has shown that resistance training is appropriate for youth when programming is dynamic and individualized. Resistance training has been shown to improve body composition, prevent injury, and improve blood lipid profiles in youth (Kraemer et al., 1989). There has been evidence indicating that training prior to puberty increases strength as a result of neuromuscular adaptations and improved technique; however, research has shown that during adolescence the increases in strength are due to neuromuscular adaptations, muscle hypertrophy, and improved technique (Langford & McCurdy, 2005). Research that examined the differences in strength based on sex have indicated that prior to puberty strength in boys and girls is the same, at 11-12 years the average strength of girls is 90% less than boys, at 13-14 years this decreases to 80%, and at 15-16 years girls have approximately 75% of the strength of boys (Langford & McCurdy, 2005). These research findings lend support for physical educators to incorporate resistance training and its underlying principles of conditioning into their physical education curriculum.
It is recommended that prior to starting a resistance training program with a child the teacher should be sure that the child has medical clearance, an understanding of the purpose of the program, a willingness to try the program, and an understanding that strength training is a lifetime pursuit. Resistance training programs for children need to take into account physiological and psychological factors. Teachers must consider the physiological maturation of each child as well as the psychological maturation and readiness of the students in order to develop resistance training programs that are developmentally appropriate (Kraemer et al., 1989). While generalized programs are best used as starter programs, maturation and readiness are factors that make it imperative that resistance programs for children are individualized and dynamic (Kraemer et al., 1989). Resistance training programs designed for children need to address several factors including: 1) the choice of exercise, 2) the order of the exercises, 3) the rest period between exercises, 4) the number of sets, and 5) the load (Kraemer et al., 1989). The activity choice is important because the child's size needs to be considered as the child must fit the equipment properly. Proper technique and skill must be taught in order for the exercise to be effective and not lead to injury (Kraemer et al., 1989). Major muscle groups should also be the focus of the exercises that are included in the program (Kraemer et al., 1989). The program should set the order of the exercises with large muscle groups being worked first, smaller muscles second and typically alternating upper body exercises with lower body exercises (Kraemer et al., 1989).
Rest periods may vary. Rest between sets should be longer with heavy weights (2-5 minutes) and during the early phases of the learning process (Kraemer et al., 1989). Shorter rest periods can be added as the students' progress through the beginning phases of learning and when muscle hypertrophy is desired. The number of sets that are incorporated into a program is the volume of work. For physical education students it is recommended that single sets are implemented in the early phase of the program (the first 2-3 weeks) and then after this period, the teacher can increase the number of sets to achieve the best results and encourage student interest in the program (Kraemer et al., 1989). Elementary and middle school students should be lifting sub-maximal resistance that should not exceed 70% of their one repetition maximum (Fees, 2003; Maina et al., 2001). In general, when designing resistance training programs, teachers should provide a 'safety zone' of two repetitions with 8-10 repetitions for heavy weight, 12-15 repetitions for moderate weight, and 18-20 repetitions for light weight (Kraemer et al., 1989). Programs for children should incorporate the principle of progressive overload. Progressive overload is when a specific muscle group is stressed throughout a set of an exercise so that the maximum muscular contraction ability is reached within that set (Kraemer et al., 1989). If a student reaches the point in a set where...
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