Three main elements of endurance performance are:
- Maximal Oxygen Consumption.
- Lactate Threshold.
- Efficiency.
1. Maximal oxygen uptake is the body's ability to take in oxygen, transfer it into the bloodstream, transport it to the working muscles and utilise efficiently within the muscle itself. This is obviously limited by the maximum pumping capacity of the heart muscle and also the arterial structure to different muscles.
2. Lactate threshold is the point whereby the muscle can no longer utilise the oxygen delivered to keep pace with performance needs. At this point lactic acid is accumulated within the muscle cell, inhibiting the natural process of oxygen delivery to the mitochondria.
3. Efficiency links sustainable power to performance velocity. Therefore, improvements in technique, equipment and different weather conditions increase or decrease the ability to transfer power to forward and uphill momentum.
First wave of Training Change is Increased Maximal Oxygen Consumption.
If untrained, a training programme can increase VO2 max substantially in just 1 week. The fitter we are, the less improvement is gained as a result of training (and of the course this improvement is harder to achieve). The good news is that VO2 max is expressed in litres / kg / min so if we lose weight as a result of training then we are actually also increasing our VO2 max. It is unusual for VO2 max to increase further following 4-6 months of regular high intensity endurance training. This is what is known as the plateau effect.
Second wave of Training Change is Lactate Threshold.
Controlled training overload over time improves mitochondrial synthesis of oxygen and waste products. There is improved capillary supply of oxygen and increased enzymes responsible for fatty acid metabolism. These changes allow the muscle to utilise more fat than glycogen to power the exercise response. Reading back to biology and Kreb's Cycle / Glycolysis we know that the bi-product of glycogen synthesis is pyruvate and then lactic acid. Once lactic acid is built up then the mitochondria can no longer adequately supply enough energy for muscular contraction. Hence, the benefits of having more available fat to power exercise at a given intensity. The exercise intensity corresponding to the point where these mechanisms switch is known as the lactate threshold. Lactate threshold takes much longer to plateau than VO2 max - sometimes up to several years.
Third Wave of Change is Efficiency.
Efficiency is simply getting more work done with lower cost. It is analogous to driving a car with the same engine and body but with flatter tyres or a window open. At the same output the car will go slower. Naturally, technique improves very slowly over a number of years and as it does then the body will be able to increase performance for a similar level of output. In cycling much of the efficiency appears to stem from learning to distribute pedalling force over a larger muscle mass (the old pull up, push down chestnut).