2. Endurance Ability to work over time More work in equal time More time doing equal work How can these variations be measured between individuals?

3. Oxygen and Endurance  Exercise  Work  Muscle Contraction  ATP  glucose breakdown  Oxygen to muscles  Heart Rate  Blood Pressure  CO2 Production Measures of Endurance

4. Individual Variation Fitness LevelWorkO2 UsedTime More fitSameLessMore Less fitSameMoreLess Fitness LevelTimeO2 UsedWork More fitSameLessMore Less fitSameMoreLess When work is equal, fit individuals can work longer When time is equal, fit individuals do more work

5. Physiological Response to Exercise Exercise = Work = Physiological Stress requires ADAPTATION (or death) Short –Term Changes  Blood Pressure  Heart Rate  Respiratory Rate  Respiratory Volume Long–Term Changes  Red Blood Cells  Blood Volume  Stroke Volume (heart increses in size)  Capillary Density in muscle fibers  Slow Twitch:Fast Twitch Ratio  Mitochondria Density in muscle fibers Influences

6. Physiological Response to Exercise Cardiovascular System Adaptations  Slow Twitch:Fast Twitch Ratio  Mitochondria Density  Red Blood Cells  Blood Volume  Stroke Volume  Capillary Density Improves O2 Delivery to Muscles Muscular System Adaptations Improves Muscle Ability to Use O2

7. Measuring Endurance  Must measure work and adaptation/response to work  Measuring work is easy  Machines – treadmill, bike, ergometer– measure work output directly  Real work – run, bike, swim – measure work indirectly by time

8. Measuring Endurance  Must measure work and adaptation/response to work  Measuring response is harder  Measure Cardiovascular Response  Changes in HR, BP, Respiration  Short-term adaptations influenced by long-term adaptations  Indirect data but easy to measure  Measure Gas Exchange  CO2 production (our lab)  O2 consumption  Requires sophisticated equipment/Harder to measure

9. Measuring Endurance – VO2 Max  Volume of O2 consumed at maximal heart rate  Units are milliliters O2/kg body weight/minute  Allows comparisons regardless of body size  Influenced by physiological adaptation to exercise (ie. training)

10. Measuring Endurance – VO2 Max  Direct Test  Measures inhaled/exhaled gas volumes  Expensive and difficult  Indirect Test  Measures heart rate as indicator of O2 consumed  Cheap and easy

11. Measuring Endurance – VO2 Max  Maximal Test  Workload is increased to maximal heart rate  Difficult and/or dangerous for non-trained individuals  Sub-maximal Test  Workload is increased to 80% of maximal heart rate  Maximal workload is extrapolated to maximal heart rate Bleep Test Rockport Walk Test

12. Measuring Endurance – Rockport Walk Test  Sub-maximal test for VO2 Max  Walk (1) mile as fast as possible  Measures workload  Time to walk  Measures response to workload  Heart rate immediately on finish  Equation predicts VO2 Max (ml/kg/min)

13. Measuring Endurance – Population Norms