Figure 1:

Figure 1 shows consumed oxygen {in red} and ventilated carbon-dioxide {in blue}, both measured in millilitres per minute. The red dotted line represents the software prediction for this clients VO2 max based on their weight, height, age and gender. 'VO2 Max' is calculated by dividing the highest absolute VO2 {6080 in this case} by the persons weight in kg. VO2 max is still considered the 'gold-standard' as an index to cardio respiratory fitness.

Figure 2:

Figure 2 shows the increase of the heart rate {in green} over the fourteen minutes or so of the test, to a maximum of 184.

Figure 3:

Figure 3 shows the changes in the body's utilization of fat and carbohydrates as exercise intensity increases. You can clearly see peak fat utilization occurring between minutes 7 & 10 into the test {130-150HR}. From this point on, fat as a fuel is increasingly replaced by carbohydrates. Just after 12 minutes in, anaerobic threshold is reached {167HR}; no fat is being used from this point on. Most people have enough stored carbohydrates {glycogen} for about 90 minutes of exercise, when using it exclusively.

Figure 4:

Figure 4 shows where the lactate threshold occurs {the green dotted line}, at 153HR in this case. Lactate is produced by the body as a result of muscle function. Up until your threshold you can process it at least as quickly as it is being produced. From your threshold upwards it begins to accumulate, often making your legs 'burn' and feel heavy. Knowing where this point is for you is vital in determining optimal sustainable race-pace.