Exercise monitoring system and methods

1. A method of controlling a subjects physical activity, comprising:

(a) monitoring a subject's blood oxygen level while the subject performs a physical activity; and

(b) maintaining said blood oxygen level at a selected level while the subject continues to perform said physical activity.

2. The method of claim 1 , wherein said blood oxygen level is maintained at said selected level by adjusting the workload of said physical activity as necessary.

3. The method of claim 1 , wherein said blood oxygen level is maintained at said selected level by adjusting the subject's level of exertion as necessary.

4. The method of claim 1 , wherein said blood oxygen level is maintained at said selected level by adjusting the subject's oxygen intake as necessary.

5. The method of claim 1 , wherein said physical activity is chosen from the group consisting of: walking, running, swimming, bicycling, skating, singing, skiing, boating, climbing, wheelchairing, snowshoeing, scuba diving, and flying.

6. The method of claim 1 , wherein said step of monitoring blood oxygen level comprises:

(a) providing an oximeter, said oximeter including a probe for non-invasively determining blood oxygen level; and

(b) positioning said probe on said subject at a location suitable for detecting the subject's blood oxygen level.

7. The method of claim 6 , wherein said probe is positioned such that said oximeter determines the subject's systemic blood oxygen level.

8. The method of claim 4 , wherein said blood oxygen level is maintained at each selected level:

(a) for a predetermined period of time;

(b) until the subject has advanced a predetermined distance; or

(c) until the subject has performed a predetermined amount of work.

9. The method of claim 1 , wherein said selected level is chosen on the basis of blood oxygen data previously obtained while said subject performed a physical activity.

10. The method of claim 1 , wherein said selected level is chosen on the basis of said subject's lactate threshold.

11. The method of claim 1 , wherein said selected level is chosen on the basis of the duration of said physical activity.

12. The method of claim 1 , further comprising the step of providing an alarm, said alarm configured for indicating when the subject's blood oxygen level is not at said selected level.

13. The method of claim 1 , further comprising the step of providing a display unit configured for displaying the subject's blood oxygen level.

14. The method of claim 13 , wherein said subject comprises a human, and said display unit is positioned so that the blood oxygen level displayed by said display unit can be viewed by said subject.

15. The method of claim 14 , wherein said physical activity comprises bicycling, and said display unit is attached to the subject's bicycle so as to be visible to the subject.

16. The method of claim 1 , further comprising the step of measuring at least one of the subject's velocity, pace, or distance traveled.

17. The method of claim 16 , wherein said measuring step comprises:

providing a GPS device operable for measuring at least one of the subject's velocity, pace or distance traveled.

18. The method of claim 16 , further comprising the step of providing a display unit configured for displaying the subject's blood oxygen level, and at least one of the subject's velocity, pace or distance traveled.

19. A method of reducing a subject's blood oxygen level variability while the subject performs a physical activity, comprising:

(a) periodically measuring a subject's blood oxygen level while said subject performs a physical activity; and

(b) adjusting the manner in which said physical activity is performed in order to reduce blood oxygen level variability.

20. A method of determining a fitness indicator of a subject, comprising:

(a) recording a subject's blood oxygen level while the subject performs a physical activity;

(b) varying the subject's workload while continuing to record the subject's blood oxygen level; and

(c) determining a fitness indicator of said subject on the basis of the recorded blood oxygen data.