Exercise Prescription Lectures

Introduction to Cardiovascular Testing

• Importance of understanding both maximal and submaximal cardiovascular tests.

• Encouragement for students to experience a maximal test to empathize with clients.

Submaximal Testing

• Definition: Tests conducted below 85% of the estimated maximum heart rate.

• Benefits:

  • Lower Risk: Significantly less risk compared to maximal tests, which can be essential for certain populations.

  • Recommended Situations: Often used in clinical environments or with patients who may have health risks.

  • Maximal Testing Needs: Generally necessary for diagnostic testing when risk factors have been identified.

• Key Assumptions for Submaximal Testing:

  • There is a linear relationship between heart rate and VO2 from 110 to 150 beats per minute.

  • An accurate heart rate is essential for estimating VO2.

Factors Influencing VO2

• Heart Rate: Central to the estimation of VO2 in submaximal tests.

• Stroke Volume: Increases with intensity, which impacts the overall VO2.

• a-vO2 Difference: Represents the amount of oxygen utilized by the tissues; tends to plateau around 40-60% of VO2 Max.

Graphical Representations

• Graphs of Responses:

  • Stroke Volume vs. Intensity shows a linear increase.

  • Heart Rate vs. Intensity also demonstrates a linear increase, with some exceptions in highly trained individuals.

• Heart Rate Deflection Point: Marks the transition from aerobic to anaerobic metabolism, often correlating with lactate threshold.

Maximal Testing

• Volitional Fatigue: Participants exert maximal effort until they can no longer continue.

• Purpose: Used for diagnostics and performance assessment, especially for athletes.

• VO2 Peak vs. Max: Many participants may reach a peak oxygen consumption that is not a true max, highlighting the need for accurate measurement criteria.

Criteria for Maximal Testing

1. Plateau in Oxygen Consumption: Indicates true VO2 max when the intensity increases but VO2 does not.

2. Blood Lactate Threshold: Levels surpassing 8 mmol/L indicate maximum effort.

3. RER (Respiratory Exchange Ratio): Expected to be about 1.0 or greater during maximal efforts, indicating reliance on carbohydrates.

4. Predicted Max Heart Rate: Should be achieved within 10 beats of age-predicted maximum (220 - age).

5. Rating of Perceived Exertion (RPE): Should exceed 17 on the Borg scale, indicating high exertion.

Estimation of VO2

• Regression Equations and Nomograms: Used to estimate VO2 max when direct measurement is not feasible.

  • Popular Protocols: Bruce (gold standard), Balkey (for older populations), and Naughton (for cardiac patients).

  • Correlation Values (R): Indicates the accuracy of the estimation; values close to 1 indicate strong relationships.

Testing Protocols and Procedures

• Graded Exercise Tests (GXT): Involve gradually increasing intensity and can be submaximal or maximal.

• Single-Stage Tests: Easier to manage but less accurate; Astrand cycle ergometer test is a common example.

• Field vs. Laboratory Tests: Field tests provide practical measurement environments outside controlled labs, while lab tests ensure standard conditions.

Consistency in Testing**

• Ensuring environmental consistency (temperature, time of day) is crucial for accurate results.

• Mechanical efficiency varies based on the mode (e.g., cycling vs. running) which presents unique challenges in submaximal testing.

Summary

• Understanding the differences between submaximal and maximal tests is crucial for accurate cardiovascular assessment.

• Accurate measurements are imperative for effective fitness evaluation and safe exercise prescription.