Physiological Adaptations to Training

1. Physiological Adaptations to Training Suzan Ayers, PhD Western Michigan University HPHE 6310

2. 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)

3. 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

4. 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

5. 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)

6. 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?

7. 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

8. 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

9. 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

10. 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

11. 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

12. 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

13. 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

14. 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

15. Benefits of strength training Improved glucose tolerance, body composition, blood lipids Help prevent bone disorders Maintain lean body mass, strength and mobility Strength Training

16. Types of contractions Static, dynamic Dynamic types: concentric (produce force) eccentric (stabilize or decelerate) 2-1-4 cadence based on this relationship

17. 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

18. 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

19. Perform daily activities & reduce disease risk Optimal/Minimal amounts vary by Individual goals Health status Fitness level Age Health-Related Fitness Training

20. 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

21. 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)

22. 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

23. 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

24. Cardiorespiratory responses Blood flow to working muscles < in children Children have < efficient respiratory systems: Higher respiratory rate Shallower breathing

25. 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

26. 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

27. 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)

28. 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

29. 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

30. 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

31. 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

32. 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)

33. 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

34. Table 12.2 (p. 176) Lifespan Sex Differences in Response to Exercise

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