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FTCE 6.7. Determine how human body systems adapt to physical activity. Muscle Fiber Types. Slow Twitch Type I Fast Twitch Type II. Event Type I Type II 100-m sprint Low High 800-m run High High Marathon High Low Olympic weightlifting Low High Barbell squat High High Soccer High High
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FTCE 6.7 Determine how human body systems adapt to physical activity.
Muscle Fiber Types • Slow Twitch • Type I • Fast Twitch • Type II
Event Type I Type II 100-m sprint Low High 800-m run High High Marathon High Low Olympic weightlifting Low High Barbell squat High High Soccer High High Field hockey High High Football wide receiver Low High Football lineman High High Basketball Low High Distance cycling High Low Table 2.2 Relative Involvement of Muscle Fiber Types in Sport Events
Variable Resistance Aerobic training endurance training Size of muscle Increase No changefibers Number of muscle No change No changefibers Movement speed Increase No change Strength Increase No change Aerobic capacity No change Increase Anaerobic capacity Increase No change Table 2.3 Major Adaptations to Resistance Versus Aerobic Endurance Training
Adaptations to resistance training are specific to the type of exercise performed.
Although aerobic endurance training increases aerobic power, it does not enhance muscle strength or size. In fact, intense aerobic endurance training can actually compromise the benefits of resistance training.
Variables Specific recommendations Volume 3-6 sets of up to 10 repetitions Load 1-10RM Rest 1-4 min Variation Typical periodization schemes designed to increase muscle strength and size Exercise selection Structural exercises: squats, cleans, deadlifts, bench presses, shoulder presses Table 4.1 Exercise Prescription Guidelines for Stimulating Bone Growth
The components of mechanical load that stimulate bone growth are the magnitude of the load (intensity), rate (speed) of loading, direction of the forces, and volume of loading (number of repetitions).
The process of hypertrophy involves both an increase in the synthesis of the contractile proteins actin and myosin within the myofibril and an increase in the number of myofibrils within a muscle fiber. The new myofilaments are added to the external layers of the myofibril, resulting in an increase in its diameter.
Stimulating Muscular Adaptations For strength: high loads, few repetitions, full recovery periods For muscle size: moderate loads, high volume, short to moderate rest periods For muscular endurance: low intensity, high volume, little recovery allowed
Type of athlete Type II fibers Bodybuilders 44% Javelin throwers 50% 800-m runners 52% Weightlifters 60% Shot-putters 62% Discus throwers 63% Sprinters and 63% jumpers Table 4.2 Proportion of Type II Fibers in Athletes Who Perform Anaerobic Activities
A general connective tissue response to aerobic endurance exercise is increased collagen metabolism.
Ithas been theorized that the endocrine system can be manipulated naturally with resistance training to enhance the development of various target tissues, thereby improving performance.
The force produced in the activated fibers stimulates receptor and membrane sensitivities to anabolic factors, including hormones, which lead to muscle growth and strength changes.
Hormone responses are tightly linked to the characteristics of the resistance exercise protocol.
Large-muscle group exercises result in acute increased serum total testosterone concentrations in men.
Growth hormone is important for a child’s normal development and appears to play a vital role in adapting to the stress of resistance training. However, GH injections result in a wide variety of secondary effects not related to changes in muscle size or strength and can, in fact, result in hypertrophy with less force production than results from exercise-induced hypertrophy.
Training protocols must be varied to allow the adrenal gland to engage in recovery processes and to prevent the secondary responses of cortisol, which can negatively affect the immune system and protein stuctures.
The cardiovascular system transports nutrients and removes waste products while helping to maintain the environment for all the body’s functions. The blood transports oxygen from the lungs to the tissues for use in cellular metabolism; blood also transports carbon dioxide—the most abundant by-product of metabolism—from the tissues to the lungs, where it is removed from the body.
The primary function of the respiratory system is the basic exchange of oxygen and carbon dioxide.
Acute aerobic exercise results in increased cardiac output, stroke volume, heart rate, oxygen uptake, systolic blood pressure, and blood flow to active muscles and a decrease in diastolic blood pressure. Resistance exercise with low intensity and high volume generally results in similar responses, some to a lesser degree.
Acute bouts of high-intensity, low-volume resistance exercise result in increased heart rate and increased diastolic and systolic blood pressure but no change in oxygen uptake, no change or a slight increase in cardiac output, and no change or a slight decrease in stroke volume.
During aerobic exercise, large amounts of oxygen diffuse from the capillaries into the tissues, increased levels of carbon dioxide move from the blood into the alveoli, and minute ventilation increases to maintain appropriate alveolar concentrations of these gases.
Aerobic exercise training results in increased maximal cardiac output and maximal oxygen uptake, slower resting heart rate, increased capillarization, improved ventilation efficiency, increased oxygen extraction, and OBLA occurring at a higher percentage of aerobic capacity.
