Physiological Adaptations to

Training

Suzan Ayers, PhDWestern Michigan University

HPHE 6310

Exercise Performance Limitations Energy System Responses to Training Muscular Adaptations to Strength Training Training Principles Cardiovascular Endurance Training Strength Training Health-related Fitness Training

Purpose of exercise training:To induce metabolic & structural adaptations to delay

fatigue

Chapter 11 Overview (Abernethy)

ATP=adenosine triphosphate High-energy molecule that provides muscular energy

PCr=phosphocreatine Major fuel source at activity onset and for up to 30

sec

Lactic acid=by-product of anaerobic glycolysis Associated with muscular fatigue

Helpful Reminders

Immediate energy system (stored energy, high-energy phosphagen, ATP-PCr system) 0-30s

Anaerobic glycolytic system (lactic acid system) 20-180s

Aerobic or oxidative system >3 min

Power and speed activities (< 1 min) Amount of ATP & PCr stored in muscles

Max exercise (30s – 2-3 mins) Lactic acid accumulation and disturbance of

the chemical/electrical gradient across cell membranes

Middle distance events (3-10 mins) Lactic acid accumulation, moderate glycogen

depletion, electrolyte distribution disturbance

Exercise Performance Limitations (p. 144)

Longer events (10-40 mins) Moderate lactic acid accumulation, partial

glycogen depletion, dehydration, chemical/electrical gradient disturbance

Very long events (>40 mins) Glycogen depletion, dehydration, ↑ body

temperature, ↓ glucose levels, Δ in ratios of amino acids in blood

Management of/Planning for Performance Limitations?

Table 11.1 (p. 145) Adaptations to strength and sprint training

Tables 11.2 (p. 146) and 11.3 (p. 147) Adaptations to endurance training ↑capacity for oxidative metabolism = <

lactic acid Only endurance training will ↑ oxidative

capacity Only [↑] speed or power training will ↑

intramuscular stores of PCr and ATP Factors influencing extent of VO2 max ↑

Initial fitness, genetics, age, type of training

Energy System Responsesto Training

Lactate threshold [Exercise] below which one can,

theoretically, ↔ exercise indefinitely w/o fatigue (or major contrib. from anaerobic system)

Below this point, ATP produced w/o ↑ lactic acid build-up

Trained: 70-85% VO2 max Untrained: 50-65% VO2 max [Exercise] or pace associated w/lactate

threshold better predictor of elite performance than VO2 max

Muscular strength: 1RM Can be increased 20-100% over several

months Age-appropriate strength training practices

Muscular power: strength x speed Force and contraction speed inversely related

Practical examples from weight room observations

Muscular endurance: Repeated sub-max reps (can be ↑ by ↑ strength)

Muscular Adaptations to Strength Training

Wks 1 to ~8=primarily neural adaptations

Hypertrophy begins after 6-8 weeks of training Max hypertrophy occurs when IIb fibers are recruited via [↑]

training

Metabolic adaptations (from intense strength

training): ↑ in intramuscular stores of ATP, PCr and glycogen in FT

fibers Results in more and faster provision of ATP, PCr Final outcome: more force possible in brief, max contractions

FITT: Frequency, intensity, time, type Specificity: training must reflect activity’s

demands Overload/Progression: progressive ↑ in

training loads (do > body typically does) Individualization: personalize program Reversibility/Regularity: ‘use it or lose it’

Adaptations continue as long as demands exist ↔ requires much less effort than initial adaptations Detraining begins within days of stopping training

Training Principles

Periodization: cyclical training designed to help athletes peak at desired time Often related to season (pre-, in-, post-) Helps prevent boredom, injury, overtraining

Overtraining (curvilinear relationship)

Leads to prolonged fatigue, frequent illness, poor performance

Often due to ↑ training volume or intensity too fast w/o adequate recovery between sessions

Continuous Training: exercise w/o breaks Table 11.4 (p. 154) Constant or varied pace Differences between [higher]/[lower] adds

variety

Interval Training: Alternating periods of exercise and rest Table 11.5 (p. 155)

This is a super summary table

Min dose (average healthy young adult): To improve VO2 max: 15min @ 60% VO2,

3x/week To improve fitness

20-60min @ 50-85% VO2, 3-5x/week Endurance athletes should approximate

intensity and duration of competition Health benefits occur w/o ↑ changes in

fitness Loss of body mass, ↓ blood pressure, ↓ risk of heart disease

Cardiovascular Endurance Training

Benefits of strength training Improved glucose tolerance, body

composition, blood lipids

Help prevent bone disorders

Maintain lean body mass, strength and mobility

Strength Training

Types of contractions Static, dynamic

Dynamic types: concentric (produce force) eccentric (stabilize or decelerate) 2-1-4 cadence based on this relationship

Types of resistance IM, IT (also isoinertial), IK

Improving strength/Hypertrophy Programs must be specific to goals Reps, sets, training volume (reps x sets),

intensity 1RM*, 10RM [Moderate-to-high], high volume for several

weeks Power: hypertrophy first then speed

development Table 11.6 (p. 158); relationships among

rest/goals

DOMS not immediate, lactic acid-based soreness

24 hrs to 1-2 weeks in duration

More intense when eccentric training used

Specific inoculation effect

Correlated with: Sub-microscopic muscle damage Edema Leakage of enzymes (creatine kinase) Inflammation Diminished strength

Perform daily activities & reduce disease risk

Optimal/Minimal amounts vary by Individual goals Health status Fitness level Age

Health-Related Fitness Training

ACSM (2011): 150 mins/wk 30-60 mins x 5 d/wk of moderate PA 20-60 mins x 3 d/wk of vigorous PA

ACSM (2008) for school-age children (6-17 yr): 60+ mins/day (cumulative), MVPA Vigorous 3+ d/wk Variety, enjoyable, all fitness components Adults vs children

Children’s Response to Exercise

Children’s Adaptations to Exercise Training

Exercise Capacity During Aging

Exercise Prescription for Older Adults

Lifespan Sex Differences in Response to Exercise

Chapter 12 Overview (Abernethy)

Children are NOT small adults

Aerobic capacity VO2 max much lower in children

Males tend to have higher VO2 max across lifespan

Endurance training can improve performance without notably changing VO2 max

Children’s Response to Exercise

Anaerobic capacity Much lower in children

Higher in males

Peaks: 14-16 yrs in females, ~20 yrs in males

Children recover faster after brief, [↑] exercise

Possibly due to < lactic acid production

Cardiorespiratory responses Blood flow to working muscles < in children

Children have < efficient respiratory systems: Higher respiratory rate Shallower breathing

Thermoregulatory responses Children are < tolerant of prolonged exercise

Children lose > metabolic heat during exercise

Children sweat @ higher relative work rate

Children sweat < during exercise

Children have a < responsive thirst mechanism

Muscular strength Similar between genders up to age 8-9 yrs Boys’ MS ↑ linearly to age 13-14 then

accelerates during adolescence Girls’ MS ↑ linearly to age 14-16 then flattens Body size, somatotype & MS more closely

related in boys than girls Simultaneous maturation of neural pathways

cause MS gains in boys & girls during/after puberty

Safety Guideline

“Lifting maximal weights should be delayed until all

the long bones have finished growing at about 17 years of age (older in

boys).” (p. 109)

Aerobic & anaerobic training VO2 max potential ↑ only 5-25% (vs 20-40% in

adults)

↓ resting heart rate

↑ max cardiac output & stroke volume

↑ work rate @ lactate threshold

↑ max minute ventilation

Children’s Adaptations to Exercise Training

Strength training recommendations Closely supervise programs & spot lifts above

head

Emphasize form/technique and minimize competition

Focus on development of muscular endurance

High rep, low weight, min. 7-10 reps per set

No max lifts before 17 yrs of age

Aerobic capacity ↓ work capacity after age 30 may be due

more to sedentary lifestyle than solely to aging

Continued training can slow the rate of decline

Sedentary people’s ↓ VO2 max generally correlated with changes in body comp

~50% of ↓ VO2 max due to ↓ in max heart rate

Ability of skeletal muscle to extract/use oxygen during exercise ↓ w/ age in the sedentary

Oxidative capacity of skeletal muscle ↓ w/ age

Exercise CapacityDuring Aging

Anaerobic capacity Peaks ~20 yrs of age

Older, sedentary folks show 6% ↓ per decade Closely related to loss of muscle mass

Anaerobic capacity & muscle size ↓ w/ age more in women than in men

Muscular strength In untrained, MS peaks early 20s

Aging, sedentary folks show 2-4% ↓ per year

Lean body mass ↓ gradually from 30-50 yrs then accelerates

Atrophy of larger, stronger FT muscle fibers Amt of connective tissue may ↑ while fiber size ↓ Age-related changes in neural input (loss of FT

fibers)

Table 12.1 (p 175) Goal of PA: ↑ / ↔ functional capacity, MS/ME,

quality of life slow/prevent onset of disease

Low to moderate [exercise] confers health benefits

Self-selected pace may enhance enjoyment & compliance

Resistance training: 2-3x/week 8-10 exercises w/ all major muscle groups 8-15 reps/set

Exercise Prescriptionfor Older Adults

Table 12.2 (p. 176)

Lifespan Sex Differences in Response to Exercise

Skill analysis-Video-Task analysis development (template online)

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