Answer:
b. high intensity; shifts to the right
Explanation:
Lactate threshold is the point where :
1) Lactate production exceeds the removal in the blood.
2) Blood and muscle lactate increase abrubtly
3) Steady state exercise can be maintained.
Hence as the athelete wants to improve his lactate threshold he should do high intensity aerobics so that large amount of lactate is produced at a faster rate than the body can absorb it. The curve will also shift to right indicating an increase in the aerobic capacity or the capacity to perform more work with same level of lactate (fatigue occurs later or higher intensities )