Unless this glycogen replacement process is started immediately and followed by .normal meals high in carbohydrate, the ability to train on subsequent days will be severely restricted. For most riders this level equates to a heartbeat in the range of 35 to 45 BPM below measured maximum heart rate. Although this intensity is at a relatively comfortable pace, level 2 training requires a marked increase in concentration over Level 1. Without this higher degree of concentration the effort can easily drop back to Level 1. Breathing rate becomes more rhythmic and is noticeably deeper.
Conversation is possible, but frequent pauses are necessary to regain breathing pattern.
Training at Level 2 results in a number of import physiological changes. The ability of the muscles to use oxygen also improves, through changes in the biochemistry of the muscle fibres, enabling you to work more efficiently, and at higher work intensities, without the onset of fatigue. A further effect is to encourage the body to use fat as a fuel source in preference to the all-important carbohydrate stores. There is a strong risk of dehydration and of the body' s carbohydrate stores becoming exhausted. This causes blood sugar levels to become very low and can lead to distressing symptoms of muscle weakness and dizziness.