Chapter 5 Flashcards
Describe the major neural adaptations that occur during anaerobic training.
Adaptations of the neural system in response to anaerobic training are fundamental to
optimizing athletic performance. These adaptations occur in the early phases of training before
hypertrophy is a major factor.
Adaptations to Anaerobic Training
• Increased agonist recruitment
• Improved neural firing rates
• Greater synchronization of timing of neural discharge
• Reduction of inhibitory mechanisms such as GTO activation
Central Adaptations
• Neural changes in spinal cord elevate fast-twitch recruitment
• Untrained populations have limited ability for maximal recruitment
• Less than 71% of muscle tissue activated during max effort in untrained people
Adaptations of Motor Units
• Maximal force requires activation of all available motor units
• Increased frequency of firing increases force production
• Increased synchronization of agonist, synergist, and antagonist muscles
• Increased activation and firing rate are primary motor unit adaptations to anaerobic
training
• Recruitment is governed by the size principle - motor units are recruited in selective
order based on recruitment threshold and firing rate.
• Heavy lifting results in hypertrophy of all muscle fibers due to the size principle.
• Advanced lifters can selectively recruit type II fibers - allows “skipping over” the type
I fiber recruitment associated with the size principle to rapidly generate maximum
force by immediately recruiting type II fibers
➢ i.e.Olympic weightlifters.
• Smaller muscles usually increase force production by increasing contraction
frequency
• Larger muscles usually increase force production by increasing motor unit
recruitment
Neuromuscular Junction and Reflex Potentiation
• Adaptations in the NMJ include an increased area of NMJ and greater length of
terminal nerve branches
• Anaerobic training can increase the intensity of the myotatic reflex - enhances the
involuntary elastic properties of muscle and connective tissue to increase force
What are the findings of EMG studies in terms of adaptations to anaerobic
training?
EMG studies have yielded several findings in relation to neural adaptations to anaerobic
training. They include the following:
• Unilateral resistance training increases strength and neural activity in the
contralateral resting muscle - known as cross-education
• Bilateral deficit is evident in untrained individuals - Force produced when both limbs
contract is lower than the sum of unilateral force production in each limb.
• Bilateral facilitation occurs in trained individuals - Force produced when both limbs
contract is greater than the sum of unilateral force production in each limb.
• Antagonist contraction during primary motion is reduced, causing increased net
force production independent of agonist force production due to reduced resistance
from antagonists
What are the primary muscular adaptations that occur with anaerobic training?
Muscular Growth (hypertrophy)
• Enlargement of muscle cross-section area (CSA)
➢ Involves increased contractile protein accretion (myosin and actin)
➢ Increased structural protein accretion (i.e. titin and nebulin)
➢ Muscle protein synthesis and growth (myogenesis) occurs in response to
Akt/mTor signaling following training
• A wide number of processes independent of hormonal activity occur to induce
hypertrophy
• Rate of protein synthesis depends on many factors including
➢ Carbohydrate and protein intake
➢ Amino acid availability
➢ Nutrient intake timing
➢ Mechanical stress of weight training
➢ Muscle cell hydration
➢ Anabolic hormonal response
➢ Training for hypertrophy should focus on:
➢ Lifting heavy loads
➢ Including eccentric muscle action
➢ Moderate to high training volumes
• Hyperplasia may play a role as well - increase in muscle fibers via longitudinal
splitting in response to high-intensity resistance training.
• Type II fibers have greater potential for hypertrophy than type I fibers
➢ The overall proportion of type I and II fibers varies in individuals and may
determine the limit of hypertrophy
Muscle Fiber Type Transitions
• Muscle fibers can change the type in response to resistance training
➢ Primarily occurs in Type IIx transitioning to Type IIa
➢ Involves shift in Myosin Heavy Chain proteins (MHCs)
➢ Transitions from Type IIa to Type I is less probably due to large difference in
MHC isoforms
Structural Changes to Muscle
• Change in pennation angle
➢ Larger pennation angle allows greater protein deposition and CSA growth
➢ Resistance training can increase the angle of pennation
• Fascicle length increases
➢ Sprint and jump training can increase vastus lateralis fascicle length
Additional Adaptations
• Increased myofibrillar volume
• Increased cytoplasmic density
• Increased sarcoplasmic reticulum and T-tubule density
• Increased sodium-potassium ATPase activity
• Reduced mitochondrial density
➢ Largely due to muscle CSA increase being greater than increase in
mitochondria
➢ Not caused by loss of existing mitochondria
• Reduced capillary density
➢ Caused by increase muscle CSA
➢ Not caused by loss of existing capillaries
• Increased H+ buffering capacity
• Increased resting CP and ATP concentration
• Increased muscle glycogen content
Describe bone tissue. What adaptations in bone tissue occur because of
anaerobic training?
Bone tissue adaptations occur in response to mechanical loading during resistance training
because of bending, compressive, and torsional forces on the tendinous bone insertions.
1. Osteoblasts migrate to the bone surface to begin remodeling
2. Secrete proteins (mostly collagen) into spaces between bone cells to increase
strength
3. Collagen forms the bone matrix and eventually mineralizes into calcium phosphate
crystals (hydroxyapatite)
4. New bone formation occurs primarily on the outer bone surface (periosteum)
5. Increases diameter and strength
Bone Physiology
• Rate of bone formation varies in axial and appendicular skeleton
• Rate difference caused by different amounts of trabecular (spongy bone) and
cortical (compact bone).
➢ Cortical bone - dense compact outer shell surrounding trabecular bone
➢ Trabecular bone more capable of growth
• New bone formation requires minimal essential strain - the threshold stimulus for
new bone formation
➢ MES level increases as bones become stronger - requires progression to
continue growth
• Bone remodeling requires six months or longer to occur
• Bone mineral density increases as strength and hypertrophy increase the demands
on the bone
Bone Remodeling in Response to Mechanical Loading
1. Application of longitudinal weight-bearing bends bone
2. Osteoblasts lay down additional collagen fibers at bending site
3. Dormant osteoblasts migrate to bend site
4. Collagen mineralizes - increasing the bone diameter
What principles should athletes follow to increase bone strength and
formation?
The specificity of loading is crucial for stimulating bone growth:
• Load the region of the skeleton where bone growth is desired
➢ I.e. running for femur strength but not wrist strength
• Novel forces stimulate bone growth
• Important to load regions commonly affected by osteoporosis:
➢ A disease where BMD and bone mass are reduced to critically low levels
➢ High-impact cyclical loading increases BMD more than low-impact activity
• Exercise selection for osteogenic stimuli:
➢ Multiple joints
➢ Direct force vectors through the spine and hip (structural exercises)
➢ Squat, power clean, deadlift (lower body)
➢ Shoulder press (upper body)
• Progressive overload
➢ Must place greater than normal demands on musculature to increase bone
mass
➢ Bones respond to higher forces - i.e. 1RM - 10RM loads
• Adaptive response reduces stress fractures
• Peak bone mass elevated by bone loading during adolescence and adulthood
• Changing distribution and direction of force vectors in resistance training presents
unique stimulus for bone growth within a given region
• If the magnitude and rate of force application is sufficient, bone growth stimulus can
be maximized with as few as 30 repetitions per workout
Describe the connective tissues.
Connective tissue includes tendons, ligaments, fascia, and cartilage and forms the critical link
between muscle and bone.
Collagen
• The primary structural component of all connective tissue.
• Includes type I collagen (bone, tendon, ligaments) and type II collagen (cartilage)
• Procollagen - parent protein to collagen
• Secreted by fibroblasts - the most common cells in connective tissue
• Enzymes cleave the protective extensions on procollagen molecule following
secretion
• Collagen filaments are organized in parallel - pairs of collagen filaments are known
as a microfibril
• Microfibrils are arranged into fibers - rely on cross-linking - strong chemical bonds
between collagen molecules
Tendons and Ligaments
• Primarily consist of tightly packed parallel arrangements of collagen bundles
• Mature tendons and ligaments contain few cells
• Significant strength in bone attachment
• Ligaments contain elastin - allows some stretch to occur during normal joint motion
• Low blood flow means tendons and ligaments are slow to regenerate and slow to
recover from injury
Fascia
• Fibrous connective tissue surrounding the muscles
• Bundles of collagen arranged in different planes
• Provides resistance from force in multiple directions
• Converges to form tendons at the end of the muscle
Cartilage
• Dense connective tissue with high ability to withstand force without damage
• Provides a smooth joint articulating surface - hyaline cartilage
• Acts as a shock absorber
• Aids in connective tissue attachments to skeleton
• Fibrous cartilage - tough cartilage found in intervertebral disks and at the tendonbone junctions.
• Receives nutrient supply via diffusion from synovial fluid - joint immobilization
prevents proper diffusion of nutrients - results in the death of healthy cartilage cells
What adaptations in connective tissue occur because of anaerobic resistance
training? How can athletes stimulate connective tissue adaptations?
Connective Tissue Adaptations to Resistance Training
• Intense anaerobic training can increase the following
➢ Collagen fibril diameter
➢ Number of covalent cross-links in the fiber
➢ Increase in the number of collagen fibrils
➢ Increase in packing density of collagen fibers
• Collectively increase tendon’s ability to withstand force as well as tendon stiffness -
the amount of force required per unit of tendon elongation
Cartilage Adaptations to Anaerobic Training
• Not fully understood
• Resistance training may prevent thinning or atrophy of cartilage
• Cartilage morphology likely determined by genetic factors
Tendon and Ligament Adaptation Stimulus
• Long-term adaptations stimulated through progressive high intensity loading
patterns using external resistance
• Low-moderate loads do not change the collagen content of connective tissue
• Forces should be exerted through a full range of motion around the joint
Cartilage Adaptation Stimulus
• Moderate-intensity exercise may be adequate for increasing cartilage thickness
• Strenuous exercise does not cause degenerative disease when overloaded
appropriately
• Tissue viability can be maintained by using a variety of exercise modalities and using
a full range of motion
What are the main acute and chronic endocrine adaptations to resistance
training?
Acute Endocrine Responses to Anaerobic Training
• Elevated testosterone, GH variants, and cortisol in men
• Rapidly stabilize after 30 minutes
• The magnitude of elevation greatest when large muscle mass used, or workout
intensity is moderate to high
• High correlation between blood lactate, H+
concentration, and cortisol and GH level
• IGF levels have a delayed response to training and depend on GH response
• Catecholamine levels reflect acute anaerobic demands
Chronic Changes in Acute Hormonal Response
• Acute hormonal responses likely mirror the ability to tolerate progressively heavier
loads from consistent anaerobic training
• Long-term acute responses likely augment the ability to tolerate and sustain higher
intensities
Chronic Changes in Resting Hormonal Concentrations
• Inconclusive research
• Resting hormone levels likely unaffected by long-term training
• Chronic elevation of hormones may be detrimental
• May reduce hormone receptor binding sensitivity
Hormone Receptor Changes
• Receptor content mediates responses to hormones
• Resistance training upregulates androgen receptors within 48-72 hours postworkout
• Resistance training stimulus mediates the magnitude of androgen receptor (AR)
changes
➢ 1 set vs 6 sets of 10 squats
▪ No difference in AR following a single set
▪ Higher volume showed downregulation of AR content 1-hour postworkout
• Protein-carbohydrate consumption post-workout attenuates the AR downregulation
What cardiovascular responses occur from anaerobic exercise?
Acute Cardiovascular Responses to Anaerobic Training
• Elevation of the following:
• Heart rate
➢ HR highest for 5 seconds following the work set
• Stroke volume
➢ Highest during eccentric phase especially with Valsalva maneuver
• Cardiac output
➢ Highest during eccentric phase especially with Valsalva maneuver
• Blood pressure
➢ Peak BP of 320/250 and HR of 170bmp reported during 95% 1RM leg press
➢ Blood pressure elevation is nonlinear
➢ Highest during concentric phase - especially at the “sticking point”
➢ No data to suggest resistance training has a negative effect on resting BP
• Degree of blood flow increase depends on:
➢ Intensity of resistance
➢ Length of time of the effort
➢ Size of muscle mass used
• Blood flow to working muscles decreased during set at intensities above 20% 1RM
because of tissue occlusion of capillaries
➢ Blood flow increases following the set - reactive hyperemia
Chronic Cardiovascular Responses to Anaerobic Training
• Heart rate:
➢ Some long-term reduction in resting HR
• Blood pressure:
➢ Decrease of 2-4% BP following long-term resistance training
• Rate-pressure product = heart rate x systolic blood pressure
➢ Constant or decreases following resistance training
• Possible slight decrease in LDL, increase in HDL
• Increased left ventricular wall thickness
➢ Does not increase relative to lean body mass - but larger overall compared to
untrained population
• Chronic training reduces the acute cardiovascular response to resistance exercise at
an absolute intensity
What respiratory responses occur from anaerobic exercise?
Ventilation Response to Anaerobic Exercise
• Resistance exercise generally not limited by ventilation rate
• Ventilation rate unaffected or moderately improved by resistance training
• Ventilation elevated slightly during resistance training - most elevated in first minute
of recovery
• Training adaptations include:
➢ Increased tidal volume and breathing frequency during maximal exercise
➢ Breathing frequency reduced but tidal volume increased during submaximal
exercise
➢ Improved ventilation efficiency is shown in trained individuals
▪ Measured by a reduced ventilatory equivalent
• The ratio of air ventilated to oxygen used by tissues
What concerns exist regarding the compatibility of aerobic and anaerobic
training?
Compatibility of Aerobic and Anaerobic Training
• Aerobic training hinders strength and power gains
• Most detrimental effect occurs on power gains
• High-volume aerobic training has the greatest negative effect
• Exercise order (aerobic vs anaerobic first) affects the degree of impact
➢ Aerobic exercise best performed after strength training
➢ Aerobic exercise reduced number of squat reps performed following 25
minutes of aerobics
• Anaerobic training increases aerobic performance
➢ Long-distance and endurance athletes show improved performance
following resistance training periods compared to non-resistance training
athletes
➢ Aerobic training not generally hindered by anaerobic training despite
competing adaptations
List the overall performance improvements that occur with anaerobic exercise.
Anaerobic Performance Improvements:
• Muscular strength:
➢ Average strength can increase from 20% to 40% depending on the current
training age of the athlete
• Power:
➢ Peak power output increases from resistance training
• Local muscular endurance:
➢ Enhanced local endurance associated with improved oxidative and buffering
capacity
➢ Adaptations include improved mitochondrial and capillary numbers, Type IIx
- Type IIa fiber transitions, and improved fatigue resistance
• Body Composition:
➢ Increases fat-free mass and lean body mass
• Flexibility:
➢ Resistance training can improve flexibility - most noticeable when paired
with flexibility training
• Aerobic capacity:
➢ Untrained individuals improve aerobic capacity via resistance training
➢ Trained individuals do not generally see improvements in aerobic capacity
➢ Circuit training can improve VO2 max
• Motor performance:
➢ Increases running economy, vertical jump, sprint speed, swing and throwing
velocity, and kicking performance
What are the phases of overtraining? What are the markers of anaerobic
overtraining?
Overtraining occurs when a combination of frequency, volume, or intensity is excessive without
sufficient rest, recovery, and nutrient intake.
Phases of Overtraining
1. Functional overreaching
• Excessive training leading to short term detriments in performance
• Recovery normally achieved within a few days or weeks
• Altered motor recruitment and sympathetic activity
2. Non-functional overreaching
• Stagnation or decrease in performance, increased fatigue, decreased vigor,
and hormonal disturbance
• Decreased circulation
• Altered excitation-contraction coupling
• Decreased glycogen
• Increased resting HR and BP
• Altered immune function and hormone concentration
• Recovery takes weeks to months
3. Overtraining Syndrome (OTS)
• Prolonged maladaptation of biological, neurochemical, and hormonal
regulation mechanisms
• Can last six months or more
• Can ruin an athletic career
• Includes:
➢ Sympathetic overtraining syndrome
• Increased sympathetic activity at rest
➢ Parasympathetic overtraining syndrome
• Increased parasympathetic activity at rest and during exercise
• Decreased force production
• Decreased glycolytic activity
• Increased sickness, infection, and emotional disturbance
• The final phase of overtraining
• Chronically suppresses many physiological systems in the body
What is detraining? What occurs during detraining? How long does it take for
detraining to occur?
Detraining refers to a decrement in performance and loss of physiological adaptations
following the cessation of anaerobic training or substantial reduction in volume, intensity, or
frequency.
The principle of reversibility states that training adaptations are transient and can disappear
when the training load is insufficient.
Detraining
• Results in partial or complete loss of the anatomical, physiological, and performance
adaptations
• Strength adaptations are maintained for up to 4 weeks
• Power and sport-specific performance may decrease more rapidly
• Recreationally trained athletes may have up to 6 weeks before serious detriments
occur
• Strength athletes may see increased oxidative fibers following extended inactivity
• At the end of 7 weeks, significant atrophy occurs in powerlifters
• Elite bodybuilders see a decrease in fat-free mass, thigh and arm girth, and average
fiber area following 13.5 months without training
