exam 2 for exercise physiology
PET 3351 Exercise Physiology Second Exam Review (Fall 2012)
Chapter IV: The Physiological Basis of Muscular Strength and Flexibility
1. Strength is operationally defined as the maximal force that can be exerted in a single effort. Using this definition, strength should be assessed using one repetition maximum (1 RM), though we often estimate strength using tests that may involve multiple repetitions.
2. In strength training and rehabilitation, emphasis should be given to both the concentric and eccentric phases of the movement. During the concentric phase, the muscle shortens from a lengthened position and during the eccentric phase the muscle lengthens from a shortened position. For example, in the execution of the squat, the subject begins in a standing position where his/her quadriceps and gluteus maximus are in a shortened position. During the descent the quadriceps and gluteus maximus lengthen in a controlled manner. This is accomplished by the quadriceps and gluteus maximus eccentrically contracting. During the ascent the quadriceps and gluteus maximus contract concentrically.
3. The strength of a contraction is a function of the number of motor units recruited and the firing frequency of the motor units. Thus strength is related not only to the size of a muscle but also the nervous system’s ability to stimulate the maximal number of units at an optimal firing frequency. In the first several weeks of strength training the rapid gains in strength are believed to be due mostly to nervous system adaptations. It is speculated that initially there is increased inhibition of inhibitory or protective mechanisms such as the Golgi tendon organs. After the first few weeks of resistance training, hypertrophic gains account for much of the strength gains. As hypertrophic gains increase they begin to account for a larger percentage of the strength gains. With time, however, hypertrophic gains slow down and then most of the strength gains,
Chapter IV: The Physiological Basis of Muscular Strength and Flexibility
1. Strength is operationally defined as the maximal force that can be exerted in a single effort. Using this definition, strength should be assessed using one repetition maximum (1 RM), though we often estimate strength using tests that may involve multiple repetitions.
2. In strength training and rehabilitation, emphasis should be given to both the concentric and eccentric phases of the movement. During the concentric phase, the muscle shortens from a lengthened position and during the eccentric phase the muscle lengthens from a shortened position. For example, in the execution of the squat, the subject begins in a standing position where his/her quadriceps and gluteus maximus are in a shortened position. During the descent the quadriceps and gluteus maximus lengthen in a controlled manner. This is accomplished by the quadriceps and gluteus maximus eccentrically contracting. During the ascent the quadriceps and gluteus maximus contract concentrically.
3. The strength of a contraction is a function of the number of motor units recruited and the firing frequency of the motor units. Thus strength is related not only to the size of a muscle but also the nervous system’s ability to stimulate the maximal number of units at an optimal firing frequency. In the first several weeks of strength training the rapid gains in strength are believed to be due mostly to nervous system adaptations. It is speculated that initially there is increased inhibition of inhibitory or protective mechanisms such as the Golgi tendon organs. After the first few weeks of resistance training, hypertrophic gains account for much of the strength gains. As hypertrophic gains increase they begin to account for a larger percentage of the strength gains. With time, however, hypertrophic gains slow down and then most of the strength gains,