Illinois State University Metabolic Adaptations to Training Chapter 5 u Aerobic training: – increases number of capillaries per muscle fiber –increases and the number of capillaries for a given cross-sectional area of muscle u Both of these changes improve blood perfusion in the muscles.

Illinois State University Fiber Types u Type I – ST – Red – Aerobic – Fatigue Resistant – Few Fibers per Motor Unit u Type IIa – FTO – Pink – Anaerobic w/aerobic capability u Type IIb – FTG – White – Purely Anaerbobic - Multiple Fibers per Motor Unit – Power Fibers

Illinois State University Response and Adaptation u Endurance training stresses ST muscle fibers more than FT fibers. u Result - ST fibers enlarge with training. u Hunters

Illinois State University Response and Adaptation u Percentages of ST and FT fibers do not appear to change u Endurance training causes Ft b fibers to take on more Ft a characteristics.

Illinois State University Response and Adaptation u Endurance training increases muscle myoglobin content by about 75% to 80% u Myoglobin stores oxygen.

Illinois State University Response and Adaptation u Endurance training increases both the number and the size of the mitochondria. u Activities of many oxidative enzymes are increased with training.

Illinois State University Response and Adaptation u These changes occurring in the muscles, combined with adaptations in the oxygen transport system, lead to enhanced functioning of the oxidative system and improved endurance.

Illinois State University Fuel Storage u Endurance-trained muscle stores considerably more glycogen than does untrained muscle. u Endurance-trained muscle also stores more fat (triglyceride) than does untrained muscle.

Illinois State University Fuel Storage  The activities of many enzymes involved in  oxidation of fat increase with training, thus free fatty acid levels increase. u This leads to increased use of fat as an energy source, sparing glycogen.

Illinois State University Training u The ideal training regimen should have a caloric expenditure of a minimum of 2,000 to a maximum of about 5,000 to 6,000 kcal per week. u There seems to be little benefit beyond this level in consideration of the added risk of injury.

Illinois State University Training u Intensity is also a critical factor in improving performance. u Adaptations are specific to the speed and duration of training bouts, so those who perform at higher intensities must train at higher intensities.

Illinois State University Training u Aerobic interval training involves repeated bouts of high-intensity performance separated by brief rest periods.

Illinois State University Training u This training, although traditionally considered only anaerobic, generates aerobic benefits because the rest period is so brief that full recovery can’t occur, thus the aerobic system is stressed.

Illinois State University Training u Continuous training is done as one prolonged bout of exercise, some many exercisers find it boring.

Illinois State University Training u The aerobic benefits from both interval training and continuous high-intensity training seem to be about the same.

Illinois State University Anaerobic Training u Anaerobic training bouts improve anaerobic performance, but the improvement appears to result more from strength gains than from improvements in the functioning of the anaerobic energy systems.

Illinois State University Anaerobic Training u Anaerobic training also improves the efficiency of movement, and more efficient movement requires less energy expenditure.

Illinois State University Anaerobic Training u Although sprint-type exercise is anaerobic by nature, part of the energy used during longer sprint bouts comes from oxidation, so muscle aerobic capacity can also be increased with this type of training.

Illinois State University Anaerobic Training u Muscle buffering capacity is increased by anaerobic training, allowing the achievement of higher muscle and blood lactate levels. u This allows the H + that dissociates from the lactic acid to be neutralized, thus delaying fatigue.

Illinois State University Anaerobic Training u Changes in muscle enzyme activity are highly specific to the type of training.