Factors Affecting Performance

1. Factor Affecting Performance (Powers CH 19)Lab Assessment of Performance (Powers CH 20)Training for Performance (Powers CH 21)

2. 1 Factors Affecting Performance • Diet • CHO intake • Hydration Bioenergetics -Anaerobic * Phosphagen * Glycolysis -Aerobic * VO2 Max * CO * O2 Delivery * O2 Extraction * Mitochondria CNS Function -Arousal -Motivation Performance Strength / Skill -Practice / NM Adaptations -Natural Endowment * Somatotype * Muscle Fiber Type • Environment • Altitude • -Heat / Humidity Powers CH 19, Fig 19.1, p409

3. Possible Sites of Fatigue Fatigue 1 Brain / “Psyche” Spinal Cord • Inability to maintain power output or force during repeated muscle contractions Peripheral Nerves Muscle Sarcolemma T-tubular System CA++ Release Actin-Myosin Interaction Cross-Bridge Tension + Heat Force / Power Output Powers CH 19, Fig 19.2, p410

4. 1 Sites of Fatigue • Central Fatigue (CNS) • Reduced # of functioning motor units involved in activity (spatial summation?) • Decreased motor unit firing rate (temporal summation?)

5. 1 Sites of Fatigue • Peripheral Fatigue • Neural Factors • NM junction • Sarcolemma and t-tubules • Repeated stimulation of sarcomere = reduction of size/freq of APs • Decreased calcium release from SR = decreased A-M cross-bridge activation • Mechanical Factors • Resulting decrease in x-bridge cycling • Energetics of Contraction • Fatigue = mismatch btwn ATP utilization and ATP production • Cellular mechanisms (mostly influenced by increased intracellular inorganic phosphate) slow down ATP utilization rate to preserve ATP concentration and cellular homeostasis

6. 3 Factors Limiting All-Out Anaerobic Performance • Less than 10 sec. (ultra short term) • Fast twitch (Type IIx) distribution • Anaerobic metabolism (ATP-PC) • Arousal / Motivation (enhances ms recruitment) • 10 sec. to 3 min. (short term) • Gradual shift from anaerobic to aerobic metabolism • FT (Type IIx and IIa) distribution • Anaerobic metabolism (glycolysis) • Elevated lactate levels and H+ concentration

7. 3 Factors Limiting All-Out Aerobic Performance • 3 – 20 min. (moderate length) • Challenges maximal aerobic “power” – athlete with highest VO2 Max at an advantage • Aerobic metabolism • O2 transport • Mitochondrial utilization • Anaerobic metabolism • Blood lactate

8. 3 Factors Limiting All-Out Aerobic Performance • 21 – 60 min. (intermediate length) • Oxidative metabolism • Conserved by running “economy” • Higher lactate threshold = greater performance (~ 90% VO2 Max) • Heat, humidity, hydration may be limiting factors • 1 – 4 hours (long term) • HHH • Liver, muscle glycogen depletion

9. 1 Laboratory Assessment • Validity • Reliability • Control • Standardization • Sport Specificity • Accurate / timely interpretation of results

10. 3 Field Tests for Aerobic Capacity • Maximum Aerobic Power • VO2 Max Testing • Large muscle groups • As sport-specific as possible • Endurance • Lactate threshold determination • Ventilatory threshold for LT prediction (eliminates need for blood draw) • Exercise Economy • Running economy = maximal gain from minimal work / energy expenditure • Influences VO2 Max scores and Lactate Threshold

11. 2 Field Tests for Anaerobic Power • Jumping power tests • 40-yard dash • Running tests (200 – 800m) • Cycling tests (Wingate 30 sec. Test) • Med ball and/or machine testing Sport specific: what do you want to find out from test??

12. Tests for Muscular Strength 2 • Strength • Max force production for 1 repitition • Power • Max force production per unit of time • P = F x d / t or w / t • Isometric Tests • Free Weights • Isokinetics • Dynamometry (Cybex, HHD,…)

13. 2 Training Principles • Overload • Stimulus beyond what tissue is accustomed • Intensity, duration, frequency of training • Specificity • Muscle fiber type(s) recruited • Principal energy system involved (aerobic v. anaerobic) • Velocity of contraction (Vmax) • Type of contraction (concentric, eccentric, isometric) • Reversibility • Influences: • Gender • Genetics • Initial fitness levels

14. 2 Training for Aerobic Power • Intensity may have greater influence than duration on VO2 Max • Interval Training • Quality / quantity of rest • Lactate management • LSD • Tempo Runs • Continuous, high intensity • Fartlek training (race strategy??)

15. 1 Injuries and Endurance Training • Stress Fx • Plantar Fascitis • Achilles Tendinitis • PFPS / Chrondomalacia 10% Rule – training intensity or duration not increased more than 10% per week

16. 1 Injuries and Endurance Training • Periostitis / “Shin Splints” • ITB Friction Syndrome • Pes Anserine Bursitis

17. 1 Training for Anaerobic Power • Interval and Plyometric Training • Metabolically Specific!!

18. 2 Training for Strength • Hypertrophy • Hyperplasia?? • Conversion • Based on training stimulus (IIx to IIa -or- IIa to IIx) • CNS Adaptations • Increased muscle recruitment • Increased motor neuron firing rates • Increased motor unit synchronization w/in movement pattern • Blunted neural inhibition (decreased GTO “firing”)

19. Training Modes Isometric Isotonic Isokinetic Periodization Systematic transfer of tr. hours between training parameters Hypertrophy / Endurance Strength Power Primary Effects of Weight Training: Power / Speed Strength Local Muscular Endurance Increased Muscle Tone Flexibility Fat Reduction / Body Comp. Aerobic Power Skeletal / Structural Agility / Coordination 3 Training for Strength

20. Training Parameters: Volume Intensity Frequency Rest Periods Exercise Order Circuit Training Supersets Standard Sets Eccentric “negatives” Accelerative movements Plyometrics PRE, PPLC2,… 3 Training for Strength

21. 1 Warm up and Flexibility • Increase in Body Core Temperature • Static Stretching • Dynamic Flexibility • Ballistic Stretching

22. 1 DOMS • Delayed onset muscle soreness 1 = structural damage to muscle fiber 2 = membrane damage 3 = calcium leaks out of SR 4 = protease activation – results in breakdown of cellular proteins 5 = inflammatory response 6 = edema and pain Powers CH 21, Fig. 21.4, p453

23. 1 Overtraining • S/Sx: • Decrease in performance • Excessive weight loss • Chronic fatigue • Psychological staleness • Elevated HR, blood lactate levels during exercise • Increase in # of infections Powers CH 21, Fig. 21.7, p458

24. 1 “Runner’s High” • β-Endorphins / β-Enkephalins • Endogenous morphine-like substances that interact with opiate receptors in brain areas involved in sensory transmission of pain impulses • β-endorphin formed in ant. pituitary gland from β-lipotrophin generated during fromation of ACTH