[Scott Johnston]

Todd:  See my thoughts below.

1) even or slight increase in HR during each work bout  – the athlete is able to complete every interval as prescribed, and the average heart rate for the first and last intervals are the same or within 5-10% of each other, and during the recovery interval the HR drops back to baseline quickly. Looks like a well-executed Zone 3 workout.  Quick recovery between reps means you were rested and had a good aerobic base capacity which could quickly restore homeostasis.  

2) large increase in HR during each work bout – the athlete is able to complete every interval as prescribed, but the average HR during each work bout is clearly rising, let’s say by 15-20%, between the first and last interval. During the recovery interval, the HR drops back to baseline quickly Looks like a well-executed Zone 4 workout with the same comments as above.

3) large increase in HR during each work bout AND HR is also increasing during the recovery interval.  Same as above, except even during the recovery interval, the average HR is increasing by 10-20%.  This was a lactate tolerance workout.   Sounds like maximum intensity rather than controlled sub-max.  Not sure what its intended purpose was. If it was for anaerobic power, the rests needed to be longer.  Many people think this is the way to do interval training, gasping with hands on knees at the end of each rep.  Minimal benefit to long distance endurance athletes.

4) Athlete unable to complete workout as prescribed, but HR is not decreasing. – Similar to the example that Scott J talked about where the athlete is slower each interval, except the HR is just going through the roof during the work periods and lower but still relatively high and increasing for the athlete during the recovery periods until the workout is over or the plug is pulled.  Same comments as above.  Probably not a very useful workout unless you are training for events under 3 minutes.