This is an excerpt from Cutting-Edge Cycling by Hunter Allen & Stephen Cheung.
Because overtraining affects the physical responses to training and adaptation, the body must also contend with a wide array of psychosocial stressors, from sports-related (team dynamics, coaches) and environmental (frequent travel, altitude) challenges to personal (relationship, work, financial) issues. Given the multitude of potential contributing factors beyond the quantification of training load, isolating the direct cause of overtraining can be difficult. The primary determinant is likely different for each cyclist. For example, a masters cyclist who juggles training time with a demanding job and a young family may overtrain from an inability to manage these multiple responsibilities. Alternately, a keen junior cyclist just starting in the sport may overtrain from trying to ride too much too soon or may develop overuse injuries from riding overlarge gears. Therefore, the social context of the cyclist must be carefully considered in managing overtraining. In addition, underlying medical issues may predispose (e.g., history of depression) or directly contribute (e.g., injury) to the onset of OTS.
Stages of Overtraining
The principle of overload is fundamental to the process of improving fitness (McNicol et al. 2009). A period of stress followed by recovery results in a “supercompensation” in which the body adapts to the imposed stress and becomes stronger, thus improving performance. The human body is highly adaptable to the stresses imposed on it as long as the stress is not excessive.
The European College of Sport Science, in its 2006 position stand (Meeusen et al. 2006), presented overtraining as a continuum from the desired “normal” and functional overload and functional overreaching (FOR), through to nonfunctional overreaching (NFOR), and ultimately to overtraining syndrome (OTS) and burnout. Although this representation is possibly an oversimplification—debate continues about whether the process of overtraining is a continuum or a series of distinct and independent phases—having standardized definitions as a basis of discussion is helpful.
- Training. A process of overload that is used to disturb the body's normal state of fitness, which results in acute fatigue (one to two days at most), adaptation by the body, and ultimately an improvement in performance. This level of training is what we do most of the time, such as a few hard interval sessions followed by a day or two of easier rides over the course of a week, or two to three weeks of progressive overload followed by a recovery week of reduced training to permit the body to adapt to the stress.
- Overtraining. Within this paradigm, overtraining is used to describe a period in which greater than normal training stress is imposed. An example may be suddenly spending two weeks doing more and harder intervals than you have been used to doing or spending a week at an intense climbing camp in the mountains, where you put in long hours and do lots of hard climbing. As explained in the three definitions that follow, overtraining can be a normal and positive process of overload and supercompensation (see functional overreaching), or it can become a negative stimulus that is more than the cyclist can handle (see nonfunctional overreaching and overtraining syndrome).
- Functional overreaching (FOR). A process in which overtraining, possibly followed by a temporary drop-off in performance lasting days to at most several weeks, results in the body adapting by becoming stronger and thus being able to produce performances that exceed the previous baseline. A critical component of FOR is a period of adequate recovery following the period of overtraining. An example may be a cyclist who spends a week at a climbing camp in the mountains, recovers at home with an easy week, and then settles back into a more normal training program during which he sees his overall riding level improve.
- Nonfunctional overreaching (NFOR). An extreme level of overtraining, often associated with inadequate recovery, in which the drop-off in performance after a period of overload is prolonged and performance stagnates or remains at baseline or lower for weeks or even months. Besides causing physiological changes, this state is often accompanied by psychological disturbances such as irritability, increased fatigue, and decreased vigor. Hormonal disturbances also are more likely within this phase. For example, NFOR might occur if the cyclist returned from a week at the climbing camp and then, without taking a recovery period, continued to push his body by doing a few additional weeks of hard training, thinking that by doing so he could take advantage of his newfound fitness and motivation to reap even greater benefits. With sufficient rest, cyclists in NFOR typically recover over a period of several months.
- Overtraining syndrome (OTS). An extreme level of overtraining, in which performance becomes impaired for many months to years. A host of psychological and physiological impairments can be present, and cyclists who reach this level often burn out completely and quit the sport. In general, rarely does physical stress alone bring about a state of OTS. Rather, the use of the term syndrome is intentional in recognition of the numerous factors that may contribute to its onset. For example, to achieve a state of OTS, the cyclist from the NFOR example described in the previous paragraph would likely have had one or more prior instances of NFOR in addition to a period of increased stress in his home, work, or team life or a physical issue such as an overuse injury or weakened immune system. Think of OTS as the perfect storm of overtraining that you never want to come near!
Although power monitors make direct quantification of training load possible, no hard and fast equation can state that a certain amount of work defines normal training, FOR, NFOR, or OTS. First, all cyclists differ in their ability to respond to a particular workload. Two cyclists riding an identical workout will respond differently based on their number of years in the sport, their particular phase of periodized training, and even their training for the previous day or week. Just as it is pointless to expect your body composition, weight, and resting heart rate to match someone else's, it is equally senseless to expect your potential for overtraining to be similar to another's. Therefore, an individual approach must be applied to training and addressing the possibility of OTS. Even when looking at a single cyclist, predicting the effect of a particular workload can be difficult because the nature of a periodized training plan generally means a wide fluctuation in workload throughout the year, making it hard to establish a baseline for workload or performance.
Read more from Cutting-Edge Cycling by Hunter Allen and Stephen Cheung.