. In physiologists' jargon this is known as cardiovascular drift, an upwards trend which is caused by two factors. First, as you run your muscles are performing a lot of metabolic work, and this increases your heart rate. Second, you are likely to become a little
, youre not training as hard as you might; but go too fast, and your session changes from an optimal aerobic workout to more of a hard slog, in which anaerobic metabolism plays a greater part.Theres been a good deal of analysis of the Conconi test
(running at your maximum aerobic steady state) is beneficial because youre working at what is supposed to be the optimal training intensity for endurance sport. If you work too hard, you risk too great a contribution of anaerobic metabolism to the energy
