When you think about it, training for high-level cycling performance is not that complicated. It comes down to improving six physiological abilities: aerobic endurance, muscular endurance, lactate threshold, aerobic capacity, anaerobic capacity and neuromuscular power. The effective development of these abilities is what allows top cyclists to ride incredibly far and fast.
Aerobic endurance is the foundation for all cycling training. It consists of the body's ability to use oxygen to produce energy for the muscles over an extended period. Aerobic endurance is the ability of the body to perform repetitive movements that range from moderate to high intensity, for a long period of time. It is one of the main fitness components which are very important for success in many sporty activities like long distance running. It is regarded as the most important physical attribute. It is also known to improve the function of the lungs, heart and blood vessels. Practically speaking, aerobic endurance is Zone 2 ability (e.g., 60% to 70% of maximum heart rate). It allows cyclists to literally spend hours riding a bike. To successfully complete long rides, cyclists must train their bodies to store large amounts of glycogen and to efficiently burn fat as a primary energy source. This is most effectively accomplished through long rides at a comfortable (i.e., conversational) pace.
Muscular endurance refers to the ability to pedal relatively big gears, at a moderate cadence (e.g., 80-90 rpm), for an extended period. This ability allows cyclists to generate significant power on the bike. While aerobic endurance is directly connected to the cardiovascular system, muscular endurance is about developing the musculoskeletal system. This can include both on-bike training and off-bike workouts; however, the most effective way to improve muscular endurance is also the simplest. Ride up a lot of hills!
Lactate threshold (LT) is the primary area of developmental focus for competitive cyclists. It is the best predictor of racing performance for many cycling events. Unlike aerobic capacity (VO2 max), lactate threshold is also highly trainable, which is one of the reasons training zones are often based on LT. In the simplest terms, lactate threshold is the highest intensity a fit cyclist can maintain for 60 minutes. Any increase in intensity beyond this threshold level requires a reduction in effort because the body starts to produce lactic acid more quickly than it can remove it. The higher a cyclist's lactate threshold, as a percentage of aerobic capacity, the faster he or she will be able to ride a bike. Lactate threshold is best developed through interval training performed at or slightly below threshold level.
Aerobic capacity is the maximum amount of oxygen the body can consume during high intensity exercise. While it is not a great predictor of cycling performance (e.g., you can have a really high VO2 max but a relatively low lactate threshold, which will lead to weak performance), it is a very good predictor of endurance sports potential. Unfortunately, aerobic capacity is not as trainable as lactate threshold. While some improvement is possible, the VO2 max for a consistently trained, experienced athlete will not change very much. Nevertheless, training for aerobic capacity should be a key component of your training regimen and typically consists of very hard, Zone 5 intervals (about 90% to 95% of maximum heart rate) lasting 3 to 5 minutes.
Anaerobic capacity is the ability to ride at a very high intensity for a relatively short period. While not a 100% effort, it is most closely connected to long sprints of 60 to 90 seconds, and very hard efforts up short hills. Anaerobic capacity is important in cycling events that require repeated explosive moves such as those in track cycling as well as road and mountain bike races where attacks and bridging between groups is common.
Neuromuscular power is the ability to pedal a very big gear, at a very high cadence, for short periods of time (10 to 30 seconds). It's all about recruiting fast twitch muscle fibers to generate force very quickly. In other words, sprinting. Cyclists that want to ride very fast over short distances must develop neuromuscular power. This is best done with short, maximum-effort sprints, 15 to 30 seconds in length with the opportunity for full recovery between hard efforts (3-4 minutes).