Chapter 9: Maintaining Cardiorespiratory Fitness During Rehabilitation

1. Chapter 9: Maintaining Cardiorespiratory Fitness During Rehabilitation Jenna Doherty-Restrepo, MS, ATC, LAT Rehabilitation Techniques in Athletic Training

2. Why is it important to maintain cardiorespiratory fitness? • While cardiorespiratory fitness is a critical component of any rehabilitation it is often the most neglected • Considerable amounts of time are spent preparing for the demands of a season • Time lost due to injury can result in considerable cardiorespiratory decrements • Cardiorespiratory Endurance • Ability to perform whole-body activities for extended periods of time without excessive fatigue

3. Training Effects on the Cardiorespiratory System • Cardiorespiratory coordinated function • Heart • Blood vessels • Blood • Lungs • Improvements due to training • Result of increased capability of each element • Providing necessary oxygen to working tissue

4. Heart Adaptations to Exercise • Heart Rate (HR) • With exercise, muscle’s use of oxygen increases resulting in an increased need for oxygen transport • Heart increases work load proportionally to intensity of exercise • Monitor HR = indirect measure of oxygen consumption • Relationship of maximum HR and maximal aerobic capacity

5. Stroke Volume (SV) • Increased blood volume pumped per beat • Approximate volume pumped = 70mL/beat • Maximal volume = 40-50% of HRmax • Above this point, increases in blood volume being pumped is related to heart rate increase

6. Cardiac Output (Q) • Collectively determined through HR and SV • Amount of blood heart is able to pump per minute • Primary determinant in maximal oxygen rate consumption • With exercise Q increases 4x-6x resting levels • Training effect • Stroke volume increases while exercise heart rate is reduced • Heart efficiency • Heart hypertrophy (heart size increases)

7. Blood Flow Adaptations to Exercise • Blood flow is modified during exercise • Flow to non-essential organs is decreased • Results in increased flow to working muscles • Blood flow to heart increases • Increase in blood vessels to musculature • Total peripheral resistance decreases during exercise due to increased vasodilation • Consistent aerobic exercise will produce reduction in overall resting BP levels

8. Blood Adaptations to Exercise • Training for improved cardiovascular function increases total blood volume • As a result of increased blood volume, increased oxygen carrying capacity increases • Total available hemoglobin increases • Overall hemoglobin concentration remains the same (may slightly decrease) with training

9. Lung Adaptations to Exercise • Pulmonary function improves with training • Volume of inspired air increases • Diffusion capacity of lungs increases • Enhances exchange of oxygen and carbon dioxide • Pulmonary resistance to air flow is also decreased

10. Overall Effects of Training • Decreased resting heart rate • Decreased heart rate at specific workloads • Increased stroke volume • Unchanged cardiac output • Decreased recovery time • Increased capillarization • Increased lung functional capacity • Decreased muscle glycogen use

11. Maximal Aerobic Capacity • Maximal oxygen consumption (VO2max) • Best indicator of cardiorespiratory endurance • Volume of oxygen consumed per body weight per unit of time • Average college athlete • 50-60 ml/min/kg • World class endurance male athlete • 70-80 ml/min/kg • World class endurance female athlete • 60-70 ml/min/kg

12. Rate of Oxygen Consumption • Greater intensity = greater oxygen consumption • Ability to perform activity is oxygen consumption related • Fatigue • Insufficient oxygen supplied to muscle • Greater % of maximal oxygen consumption = less time activity can be performed • Factors affecting maximal rate • External respiration (involving ventilatory process) • Gas transport • Internal respiration (use of oxygen by cells) • High maximal aerobic capacity indicates all 3 levels are working well

13. Maximal Aerobic Capacity: Inherited Characteristic • Genetically determined range • Training allows athlete to obtain highest level within that range • Fast-Twitch vs. Slow-Twitch Muscle Fibers • Range is largely determined by metabolic and functional capability of skeletal muscle • Higher % of fatigue resistant, endurance oriented slow twitch fibers will enable individual to utilize more oxygen and have higher VO2max

14. Cardiorespiratory Endurance and Work Ability • Cardiorespiratory endurance is key component in individual ability to perform daily activities • Factors impacting work ability • Fatigue, • Workload, and • Percent of VO2max • Training goal • Increase ability of cardiorespiratory system to supply a sufficient amount of oxygen to working muscles

15. Producing Energy for Exercise • Cellular Metabolism • Generate energy required to function • Breakdown of nutrients result in formation of ATP • ATP produced from glucose breakdown • Glucose from blood or glycogen (muscle or liver) broken down to glucose converted to ATP • Fat and protein can be utilized to produce ATP • Fat is utilized when glycogen stores become depleted • Activity becomes more duration/endurance oriented • Different activities have differing energy needs and rely on different cellular processes

16. Aerobic vs. Anaerobic Metabolism • Both generate ATP • Initial ATP production from glucose occurs in muscle (without oxygen = anaerobic) • Transition to glucose and fat oxidation (requiring oxygen = aerobic) to continue activity • Generally both systems occur to a degree simultaneously • Type of ATP production relative to intensity • Short burst (high intensity) = anaerobic • Long duration (sustained intensity) = aerobic

17. Techniques for Maintaining Cardiorespiratory Endurance • Primary concern • Nature of injury and techniques available as a result of injury • Upper vs. Lower extremity injury • Match fitness exercises to functional activities specific to sport • Goal • Maintain fitness levels

18. Continuous Training • FITT Principle • Frequency • Intensity • Type (mode) • Time (duration) • Frequency • Competitive athlete should be prepared to engage in fitness activity 6 times per week, allowing 1 day for body repair and maintenance

19. Intensity • Should be heart rate controlled and monitored • Goal is to plateau heart rate at desired level • Monitor pulse • Preferably radial pulse • Should be engaged in workout for 2-3 minutes prior to checking • Workouts should be set as percentage of heart rate max (60-90%) • Appropriate estimate of HRmax = 220-Age • Karvonen formula • Target HR = HRrest + (0.6[HRmax-HRrest]) • Rate of Perceived Exertion (RPE) • Scale (6-20) that can be used to rate exertion level during activity

20. Type of Exercise • For continuous training activity must be aerobic • Easy to regulate intensity (speed up or slow down) • Intermittent exercise is too variable (speed and intensity) • Time (duration) • Minimal improvements = exercise for 20 minutes • ACSM recommends 20-60 minutes with HR elevated to training levels • Greater duration = greater improvements

21. Interval training • Intermittent activities involving periods of intense work and active recovery • Must occur at 60-80% of maximal heart rate • Allows for higher intensity training at short intervals over an extended period of time • Most anaerobic sports require short burst which can be mimicked through interval training • HR may reach 85-95% of maximum at peak and 35-45% during rest • Should be combined with continuous training

22. Fartlek training • Cross-country running • Similar to interval training in that activity occurs over a specific period of time, but pace and speed are not specified • Consists of varied terrain which incorporates varying degrees of hills • Dynamic form of training – less regimented • Must elevate heart rate to minimal levels to be effective • Popular form of training in off-season