8 C H A P T E R Physiological Adaptations to Anaerobic and Aerobic Endurance Training Programs William J. Kraemer
Chapter Outline Anaerobic training Detraining Endocrine responses to anaerobic and aerobic exercise Aerobic endurance exercise training Overtraining
P erformance gains typically are related to changes in more than one physiological system. The training program must train each physiological system in careful balance with specific performance goals in mind.
Key Concepts of Physiological Adaptations to Exercise Training Each person responds differently to each training program. There is a psychological component to training. The magnitude of the physiological or performance gain is related to the size of an athlete’s adaptational window. The amount of physiological adaptation depends on the effectiveness of the exercise prescriptions used in the training program. Training for peak athletic performance is different from training for optimal health and fitness.
Relationship Between Energy Delivery Systems and Exercise Duration
Anaerobic Training: Two Primary Energy Systems The phosphagen system provides immediate ATP energy for fast and powerful movements. This system is used during short-duration, high-intensity activities with long rest periods. The glycolytic system breaks down glucose to lactic acid and is the next most readily available source of ATP. This system is used during longer, less intense exercise with shorter rest periods. The oxidative system also plays a role in maintaining power output and recovering energy stores.
Table 8.2 Comparison of Physiological Adaptations to Resistance Training and Aerobic Endurance Training (continued) Variable Results following Results following aerobic resistance training endurance training Performance Muscle strength Increases No change Muscle endurance Increases for high power Increases for low power output output Aerobic power No change or increases Increases slightly Maximal rate of Increases No change or decreases force production Vertical jump Ability increases Ability unchanged Anaerobic power Increases No change Sprint speed Improves No change or improves slightly
Table 8.2 (continued) (continued) Variable Results following Results following aerobic resistance training endurance training Muscle fibers Fiber size Increases No change or increases slightly Capillary density No change or decreases Increases Mitochondrial Decreases Increases density Fast heavy-chain Increases in amount No change or decreases myosin in amount Type II muscle Almost all to Type IIa With spring interval, a fiber subtype majority to Type IIa conversion
Table 8.2 (continued) (continued) Variable Results following Results following aerobic resistance training endurance training Enzyme activity Creatine Increases Increases phosphokinase Myokinase Increases Increases Phospho- Increases Variable fructokinase Lactate No change or variable Variable dehydrogenase
Table 8.2 (continued) (continued) Variable Results following Results following aerobic resistance training endurance training Metabolic energy stores Stored ATP Increases Increases Stored creatine Increases Increases phosphate Stored glycogen Increases Increases Stored May increase Increases triglycerides
Table 8.2 (continued) Variable Results following Results following aerobic resistance training endurance training Connective tissue Ligament strength May increase Increases Tendon strength May increase Increases Collagen content May increase Variable Bone density No change or increases No change or increases Body composition % body fat Decreases Decreases Fat-free mass Increases No change
W ith heavy resistance training, all muscle fibers get bigger because they are all recruited in consecutive order by their size to produce high levels of force. In advanced lifters, the central nervous system might adapt by allowing these athletes to recruit some motor units not in consecutive order, but by recruiting larger ones first to help with greater production of power or speed in a movement.
Theoretical Interplay Between Neural and Muscle-Tissue Factors
I ncorporating resistance training into an aerobic endurance training program can improve the ability of the heart, lungs, and circulatory system to function under conditions of high pressure and force production. Resistance exercise, however, is not effective in increasing maximal oxygen consumption.
Endocrine Responses to Anaerobic and Aerobic Exercise During high-intensity exercise, the concentrations of hormones in blood and other body fluids can increase 10 to 20 times over their levels at rest. Exercise-induced mechanisms contribute to changes in hormone concentrations, including changes in clearance rates in the liver, shifts in blood volume, receptor interactions. hormone degradation, and
Results of Aerobic Endurance Exercise Training Reduced body fat Increased maximal oxygen uptake Increased respiratory capacity Lower blood lactate concentrations Increased mitochondrial and capillary densities Improved enzyme activity
C ombining resistance and aerobic endurance activities appears to interfere primarily with strength and power performances.
Responses of Muscle Fibers With Maximal Simultaneous Training for Strength and Endurance
O vertraining (defined as excessive frequency, volume, or intensity of training, resulting in fatigue) can cause dramatic performance decreases in athletes of all training levels.
Markers of Anaerobic Overtraining Psychological effects: decreased desire to train; decreased joy from training Acute epinephrine and norepinephrine increases beyond normal exercise-induced levels Performance decrements, although these occur too late to be a good predictor
Markers of Aerobic Overtraining (continued) Increased creatine kinase Altered cortisol concentration Decreased total testosterone concentration Decreased ratio of total testosterone to cortisol Decreased ratio of free testosterone to cortisol Decreased ratio of total testosterone to sex hormone-binding globulin Decreased sympathetic tone Increased sympathetic stress response
Relative Responses of Physiological Variables to Training and Detraining