Adaptations to Aerobic and Anaerobic Training

CHAPTER 12 Adaptations to Aerobic and Anaerobic Training

Overview

  • Adaptations to aerobic training

  • Adaptations to anaerobic training

  • Adaptations to high-intensity interval training

  • Specificity of training and cross-training

Adaptations to Aerobic Training

Cardiorespiratory Endurance (1 of 2)

  • Cardiorespiratory endurance

    • Definition: The ability to sustain prolonged, dynamic exercise.

    • Improvements occur through multisystem adaptations:

    • Cardiovascular system

    • Respiratory system

    • Muscular system

    • Metabolic system

Cardiorespiratory Endurance (2 of 2)

  • Endurance training leads to:

    • Increase in maximal endurance capacity:

    • $ riangle ext{V} ext{O}_2 ext{max}$

    • Increase in submaximal endurance capacity:

    • Heart rate (HR) decreases at the same submaximal exercise intensity, which is more related to competitive endurance performance.

Major Cardiovascular Changes

  • Key physiological changes include:

    • Heart size

    • Stroke volume

    • Heart rate

    • Cardiac output

    • Blood flow

    • Blood volume

    • Red cell volume

Cardiovascular Adaptations (1 of 7)

  • Oxygen transport system and the Fick equation:

    • Equation: $ ext{V} ext{O}2 = ext{SV} imes ext{HR} imes ( ext{a-v}) ext{O}2 ext{ difference}$

    • Changes associated with adaptations:

    • $ riangle ext{V} ext{O}2 ext{max} = riangle ext{SV}{ ext{max}} imes ext{HR}{ ext{max}} imes riangle ( ext{a-v}) ext{O}2$

Cardiovascular Adaptations (2 of 7)

  • Heart Size

    • With training, there is an increase in both the mass of the heart and left ventricular (LV) chamber size.

    • This increase allows for greater LV filling and stroke volume.

    • The change is largely attributed to increased plasma volume (volume loading effect).

Cardiovascular Adaptations (3 of 7)

  • Stroke Volume (SV) increases post-training:

    • Observed at rest, during submaximal exercise, and maximal exercise.

    • Increase in plasma volume results in increase in end-diastolic volume (EDV) leading to greater preload, therefore increasing SV.

    • Significant decrease in resting and submaximal HR with training increases filling time and EDV.

    • Increased LV mass leads to a stronger force of contraction and decreased end-systolic volume (ESV).

    • Adaptations in stroke volume decrease with increasing age.

Cardiovascular Adaptations (4 of 7)

  • Resting Heart Rate (HR):

    • Decreases markedly (~1 beat/minute per week of training).

    • Reflects increased parasympathetic activity and decreased sympathetic activity in the heart.

  • Submaximal HR:

    • Decrease in HR for the same absolute exercise intensity, especially apparent at higher intensities.

  • Maximal HR:

    • No significant change with training but decreases with age.

Cardiovascular Adaptations (5 of 7)

  • HR and SV Interactions:

    • The relationship is vital for optimizing cardiac output.

  • HR Recovery:

    • Faster recovery indicates better cardiorespiratory fitness.

  • Cardiac Output ($Q$):

    • Little to no change at rest or during submaximal exercise, but maximal cardiac output increases significantly due to increased SV.

Cardiovascular Adaptations (6 of 7)

  • Increased blood flow to active muscles.

    • Enhanced capillarization and capillary recruitment leading to improved capillary-to-fiber ratio which increases total cross-sectional area for capillary exchange.

  • Reduced blood flow to inactive regions.

  • Increased total blood volume assists in preventing decreases in venous return due to the increased blood volume in capillaries.

Cardiovascular Adaptations (7 of 7)

  • Blood Volume Changes:

    • Total blood volume increases rapidly due to increased plasma volume (via more plasma proteins and water/Na+ retention) in the initial two weeks.

    • Increase in red blood cell volume with a possible decrease in hematocrit percentage results in decreased plasma viscosity.

Respiratory Adaptations

  • Pulmonary ventilation:

    • Decreases at given submaximal intensity, increases at maximal intensity due to larger tidal volumes and respiratory rates.

  • Pulmonary diffusion:

    • Remains unchanged at rest and submaximal intensity, increases at maximal intensity due to increased lung perfusion.

  • Arterial-venous O2 difference:

    • Increases due to enhanced O2 extraction and blood flow to active muscles with better oxidative capacity.

Muscular Adaptations (1 of 3)

  • Increased expression of PGC-1 (peroxisome proliferator-activated receptor-γ coactivator-1), a key factor in mitochondrial biogenesis termed as the “master switch.”

  • Activation of signaling pathways:

    • Includes pathways such as Calcineurin, CaMK, AMPK, and mitogen-activated kinase p38 to promote adaptations.

Muscular Adaptations (2 of 3)

  • Fiber type changes:

    • Increase in size and number of type I fibers while type II fibers (IIx) may start functioning similarly to type IIa fibers.

  • Capillary supply:

    • Increased number of capillaries per fiber, which is crucial for improvements in V•O2max.

  • Myoglobin content:

    • Increases by 75% to 80%, supporting heightened oxidative capacity in the muscle.

Muscular Adaptations (3 of 3)

  • Mitochondrial Function:

    • Increases in size and number of mitochondria, with the degree of change dependent on the training volume.

    • Mitophagy: Quality control process for mitochondria.

  • Oxidative enzymes:

    • Enzyme activity increased with training and continues to increase even after V•O2max plateaus, aiding in glycogen sparing.

Metabolic Adaptations (1 of 2)

  • Lactate Threshold:

    • Increases to a higher percentage of V•O2max, with decreased lactate production and increased lactate clearance allowing for greater intensity exercise without lactate accumulation.

  • Respiratory Exchange Ratio (RER):

    • Decreases at both absolute and relative submaximal intensities, increasing fat oxidation and decreasing glucose oxidation.

Metabolic Adaptations (2 of 2)

  • Resting and submaximal V•O2:

    • Resting V•O2 remains unchanged, while submaximal V•O2 may remain the same or decrease slightly with training.

  • Maximal V•O2 (V•O2max):

    • Serves as the best indicator of cardiorespiratory fitness, showing a significant increase (15%-20%) with training due to increases in cardiac output and capillary density.

Long-Term Improvement

  • Highest possible V•O2max can be achieved after 12 to 18 months of training.

  • Performance improvements can continue even after V•O2max plateaus, with the lactate threshold also increasing with continued training.

Individual Response Factors (1 of 2)

  • Training Status and Pretraining V•O2max:

    • Relative improvement in V•O2max is dependent on initial fitness level.

    • More sedentary individuals exhibit greater increases relative to their baseline.

    • More fit individuals demonstrate lesser relative gains.

  • Heredity:

    • There exists a finite V•O2max range influenced by genetics, which can be modified through training.

    • Identical twins show closer V•O2max values than fraternal twins, with 25%-50% variance attributable to genetic factors.

Individual Response Factors (2 of 2)

  • Sex Differences:

    • Untrained females have a lower V•O2max compared to untrained males, whereas trained females' V•O2max approaches that of trained males.

  • High vs. Low Responders:

    • Variability (genetic factors) exists in the response to training stimuli that can lead to different V•O2max outcomes.

Fatigue Across Sports

  • Endurance training is crucial not only for endurance-focused sports but also benefits nonendurance athletic events, leading to maximized cardiorespiratory endurance across all sports.

Aerobic Deconditioning

  • Consequences of bed rest include:

    • Associated diseases and disabilities resembling effects of weightlessness in space.

    • Declines in body weight, lean body mass, cardiovascular fitness.

    • Greater losses seen in individuals with higher initial V•O2max levels.

Adaptations to Anaerobic Training (1 of 2)

  • Improvements in anaerobic power and capacity as measured by tests such as the Wingate anaerobic test, which is recognized as the gold standard for assessing anaerobic power.

  • Muscle Adaptations:

    • Increases in cross-sectional area of type IIa and IIx muscle fibers, to a lesser extent, type I fibers.

    • Decrease in the percentage of type I fibers while the percentage of type II fibers increases.

Adaptations to Anaerobic Training (2 of 2)

  • ATP-PCr system:

    • Minimal changes in enzymatic activities with training; shifts toward greater strength performance.

  • Glycolytic system:

    • Increases in key glycolytic enzymes (phosphorylase, PFK, LDH, hexokinase) with training, resulting in improved muscle performance from strength gains.

Adaptations to High-Intensity Interval Training (HIIT)

  • HIIT presents a time-efficient method for achieving many beneficial adaptations typically associated with traditional endurance training.

  • It stimulates mitochondrial biogenesis and enhances carbohydrate and fat transport and oxidation capabilities in muscles.

Specificity of Training and Cross-Training

  • Specificity of Training:

    • V•O2max is significantly higher in activities that are specific to the sport being trained for due to adaptations in individual muscle groups.

  • Cross-Training:

    • Involves training various fitness components simultaneously or preparing for multiple sports.

    • Strength benefits, however, may be lessened by concurrent endurance training while endurance gains remain largely unaffected by strength training.

Selected Muscle Enzyme Activities (1 of 2)

  • The following enzyme activities are observed in untrained, anaerobically trained, and aerobically trained men:

    • Oxidative system:

    • Succinate dehydrogenase:

    • Untrained: 8.1

    • Anaerobically trained: 8.0

    • Aerobically trained: 20.8*

Selected Muscle Enzyme Activities (2 of 2)

  • Anaerobic enzymes:

    • Creatine kinase:

    • Untrained: 609.0

    • Anaerobically trained: 702.0*

    • Aerobically trained: 589.0

    • Glycolytic system:

    • Phosphorylase:

      • Untrained: 5.3

      • Anaerobically trained: 5.8

      • Aerobically trained: 3.7*

Conclusion

  • These comprehensive adaptations from aerobic and anaerobic training highlight the complexities of human physiology, emphasizing the importance of specificity, individuality, and the roles of various systems in exercise performance.