METABOLIC ADAPTATIONSTO EXERCISE

METABOLIC ADAPTATIONSTO EXERCISE

CHAPTER 6CHAPTER 6

Aerobic (endurance) training leads to Improved blood flow, and Increased capacity of muscle fibers to

generate ATP.

Anaerobic training leads to Increased muscular strength, and

Increased tolerance for acid-base imbalances during highly intense effort.

Aerobic vs Anaerobic Training

Adaptations to Aerobic Training

Muscular changes in fiber size, blood and oxygen supply, and efficiency of functioning

Improved efficiency of energy production

Improved submaximal aerobic endurance and VO2max.

Muscular Adaptations

Increased size of ST fibers

Increased number of capillaries supplying the muscles

Increased myoglobin content of muscle (allowing muscle to have more oxygen)

Increased number, size, and oxidative enzyme activity of mitochondria

Adaptations Affecting Energy Sources

Trained muscles store more glycogen and triglycerides than untrained muscles.

FFAs are better mobilized and more accessible to trained muscles.

Muscles’ ability to oxidize fat increases with training.

Muscles’ reliance on fat stores first conserves glycogen during prolonged exercise.

USE OF ENERGY SOURCES WITH INCREASING INTENSITY

Aerobic Training Considerations

Volume Frequency of exercise bouts

Duration of each exercise bout

Intensity Interval training

Continuous training

Training Volume

Volume is the load of training in each training session and over a given period of time.

Adaptations to given volumes vary from individual to individual.

An ideal aerobic training volume appears to be equivalent to an energy expenditure of about 5,000 to 6,000 kcal per week.

Athletes who train with progressively greater workloads eventually reach a maximal level of improvement beyond which additional training volume will not improve endurance or VO2max.

.

TRAINING VOLUME AND VO2MAX.

Training Intensity

Muscular adaptations are specific to the speed as well as duration of training.

Athletes who incorporate high-intensity speed training show more performance improvements than athletes who perform only long, slow, low-intensity training.

Continuous training involves one continuous, high-intensity exercise bout.

Aerobic intervals are repeated, fast-paced, brief exercise bouts followed by short rests.

Adaptations to Anaerobic Training

Increased muscular strength

Slightly increased ATP-PCr and glycoytic enzymes

Improved mechanical efficiency

Increased muscle oxidative capacity (for sprints longer than 30 s)

Increased muscle buffering capacity

Muscle Buffering Capacity

Anaerobic training improves muscle buffering capacity, but aerobic training does little to increase the muscles' capacity to tolerate sprint-type activities.

Improved muscle buffering capacity allows sprint-trained athletes to generate energy for longer periods before fatigue limits the contractile process.

Anaerobically Aerobically Untrained trained trained

Aerobic enzymesOxidative systemSuccinate dehydrogenase 8.1 8.0 20.8Malate dehydrogenase 45.5 46.0 65.5Carnitine palmityl transferase 1.5 1.5 2.3

Anaerobic enzymesATP-PCr systemCreatine kinase 609.0 702.0 589.0Myokinase 309.0 350.0 297.0Glycolytic systemPhosphorylase 5.3 5.8 3.7Phosphofructokinase 19.9 29.2 18.9Lactate dehydrogenase 766.0 811.0 621.0a Denotes a significant difference from the untrained value.

aa

a

a

a

aa

Selected Muscle Enzyme Activities (mmol g min ) for Untrained, Anaerobically Trained, and Aerobically Trained Men

-1. . -1

Methods of Monitoring Training Changes

Lactate threshold tests

Comparing lactate values taken after steady-state exercise at various times in the training period

Repeated measurements of VO2max.