All are features of exercise except

Options

A. left shift of Hb -`O_(2)` dissociation curve
B. increased blood supply to muscle
C. increase stroke volume
D. increase `O_(2)` extraction

Answer

To solve the question "All are features of exercise except," we need to analyze the given options and identify the one that does not align with the physiological changes that occur during exercise.

### Step-by-Step Solution:

1. **Understand the Hemoglobin Oxygen Dissociation Curve**:
- The hemoglobin oxygen dissociation curve is a graphical representation of how hemoglobin binds to oxygen at different partial pressures of oxygen.
- It is typically a sigmoid curve, indicating that hemoglobin's affinity for oxygen changes with varying oxygen concentrations.

2. **Evaluate the First Option**:
- The first option states "left shift to hemoglobin oxygen dissociation curve."
- A left shift indicates an increased affinity of hemoglobin for oxygen, meaning hemoglobin holds onto oxygen more tightly and releases less to the tissues.
- During exercise, the body requires more oxygen, leading to a right shift in the curve (known as the Bohr effect), which facilitates oxygen release to the muscles.

3. **Conclusion for the First Option**:
- Since a left shift is not a feature of exercise (the correct feature is a right shift), this option is the one that does not belong.

4. **Evaluate the Remaining Options**:
- **Increased blood supply to the muscles**: This is correct. During exercise, muscles require more oxygen, leading to increased blood flow.
- **Increased stroke volume**: This is also correct. Stroke volume, the amount of blood pumped by the heart per beat, increases during exercise to supply more oxygen.
- **Increased oxygen extraction**: This is correct as well. Tissues extract more oxygen during exercise due to increased metabolic activity.

5. **Final Answer**:
- The only statement that is not a feature of exercise is the left shift of the hemoglobin oxygen dissociation curve. Therefore, the correct answer is the first option.