Maintaining Aerobic Capacity & Endurance During Rehabilitation

1. Maintaining Aerobic Capacity & Endurance During Rehabilitation Chapter 10

2. Why is it important to maintain cardiorespiratory fitness? • It is a critical component of any rehabilitation, but 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 activity is a coordinated function of 4 components to transport O2throughout body • Heart • Blood vessels • Blood • Lungs • Improvements due to training • Results in  capability of each of the above elements • Provides necessary oxygen (O2) to working tissue

4. Adaptations of the Heart to Exercise • Heart Rate (HR) • With exercise, the muscle’s use of  O2 results in an  need for O2 transport • Heart work load increases proportionally to intensity of exercise • Monitor HR = indirect measure of  consumption

5. Stroke Volume (SV) • Volume of blood being pumped/beat • Approximate volume pumped = 70mL/beat • Maximal volume = 40-50% of HRmax • 110-120 beats/min. • Above this point  in volume being pumped is related to heart rate 

6. Cardiac Output (Q) – • Amount of blood heart pumps/minute • Q = SV x HR • Normal = 5L blood/min. @ rest • Primary determinant of maximal O2 rate consumption • With exercise, Q  4x-6x of resting levels (normal – endurance athlete) • Training effect • Stroke volume  while exercise heart rate  • Heart efficiency • Heart hypertrophy w/ exercise • Females 5-10% higher Q than males (likely due to lower concentration of hemoglobin in the female, which is compensated for during exercise by an increased cardiac output

7. Adaptations in Blood Flow • Blood flow is modified during exercise • Flow to non-essential (exercise related) organs is decreased • Results in increased flow to working muscles • Even though blood flow to heart increases – the percentage of total cardiac output remains unchanged • Increase in blood vessels to musculature • Total peripheral resistance decreases during exercise • Increase in vasodilation

8. Blood Pressure (BP) • Determined by cardiac output in relation to total peripheral resistance to blood flow • Systolic pressure - pressure created by heart contraction (top number) • Diastolic pressure - relaxation of heart (bottom number) • Systolic pressure  in proportion to O2 consumption & Q • Consistent aerobic exercise will produce  in overall resting BP levels

9. Adaptations in the Blood • Training for improved cardiovascular function  total blood volume • As a result of increased blood volume, increased O2 carrying capacity increases • Total available hemoglobin increases • Overall hemoglobin concentration remains the same or may slightly  with training • Hemoglobin - O2 is transported throughout the system; iron-containing protein that has the capability of easily accepting or giving up molecules of O2 as needed

10. Adaptations of the Lungs • Pulmonary function improves with training • Volume of inspired air  • Diffusion capacity of lungs  • Enhances exchange of O2 and carbon dioxide • Pulmonary resistance to air flow is also  • Overall Effects of Training •  resting heart rate •  heart rate at specific workloads •  recovery time •  muscle glycogen use • Unchanged cardiac output •  stroke volume •  capillarization •  lung functional capacity

11. Maximal Aerobic Capacity • Maximal oxygen consumption (VO2max) • Volume of O2 consumed per body weight per unit of time (ml/min/kg) • Best indicator of cardiorespiratory endurance • 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 • Rate of O2 consumption is about the same for all individuals, depending on fitness level per activity • Greater intensity = greater O2 consumption • A person’s ability to perform activity is related to amount of O2 required by that activity • Ability is limited by the max. rate of O2 consumption the person is capable of delivering into the lungs • Fatigue occurs when: • Insufficient O2 supplied to muscle • Greater % of maximal O2 consumption during an activity = less time activity can be performed

13. Factors affecting maximal rate • External respiration (involving ventilatory process) • Gas transport – accomplished by cardiovascular system • Internal respiration (use of O2 by cells to produce energy) • Most limiting factor is ability to transport O2 through system • High maximal aerobic capacity indicates all 3 levels are working well

14. 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 of VO2max 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 O2 and have higher VO2max

15. Cardiorespiratory Endurance and Work Ability • Cardiorespiratory endurance is key component in individual ability to perform daily activities • Fatigue & percent of VO2max are closely related for particular workload (A vs. B) • Training goal • Increase ability of cardiorespiratory system to supply a sufficient amount of O2 to working muscles

16. Producing Energy for Exercise • Cellular Metabolism • To Grow, Generate energy, Repair damaged tissue, Eliminate waste • Energy is produced from the breakdown of nutrients resulting in formation of Adenosine triphosphate (ATP) (primary energy store) • ATP is produced in muscle tissue • Glucose from blood or glycogen (muscle or liver) is broken down to glucose & converted to ATP • Glucose not needed immediately is stored as glycogen in the resting muscle & liver; can be later converted back • 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

17. Aerobic vs. Anaerobic Metabolism • Both systems generate ATP • Initial ATP production from glucose occurs in muscle (without O2 = anaerobic) • Transition to glucose & fat oxidation (requiring O2 = 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

18. Excess Post-exercise Oxygen Consumption (Oxygen Deficit) • With  intensity, insufficient amounts of O2 are available which results in O2 deficit • Occurs initially during activity (1st 2-3 min. of exercise) – body adapts • Hypothesized that it may be a result of initial lactic acid production • Deficit may be the result of disturbance in mitochondrial function due to increased temperature

19. Techniques for Maintaining Cardiorespiratory Endurance • Primary concern • Nature of injury & techniques available as a result of injury • Upper vs. Lower extremity injury & options • Match fitness • Engagement of functional activities specific to sport to maintain fitness • Goal • Maintain fitness levels

20. 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

21. Intensity • Should be heart rate controlled & 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% ACSM recommendation) • 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

22. 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

23. Interval training • Intermittent activities involving periods of intense work & 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

24. Fartlek Training • Cross-country running that originated in Sweden • Speed play • Similar to interval training in the fact activity occurs over a specific period of time but pace and speed are not specified • Puts surges into workout, varying length of surges to specific needs • 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

25. Par Cours • Combination of continuous & circuit training • Jogging short distances, from station to station, & performing a designated exercise • Gain aerobic fitness while performing calisthenics • Found typically in recreational parks