Trained, overreached or overtrained? How to avoid the recovery lottery!

Using soccer as an illustration, Alan Wells explains how the risk of overreaching/overtraining and chronic fatigue can be reduced in high-achieving younger sportsmen and women

For an athlete to improve his/her physical capabilities, the physical stress they experience must be sufficient to overload the targeted physiological systems. Such an approach often leads to a transient reduction in performance as temporal changes within the body such as reduced muscle glycogen, microscopic muscle damage and a reduction in neural function occur⁽¹⁾.

However, if training programmes are designed appropriately and provide sufficient periods for recovery and rejuvenation, the process of super-compensation occurs leading to a subsequent improvement in performance (figure 1). This transient state of fatigue is termed ‘overreaching’, and is a necessary condition for elite players to experience if they are to gain performance improvements. However, when players endure high levels of physical loading without sufficient recovery the manifestation of chronic fatigue begins, a condition commonly known as overtraining (figure 1).

Overtraining within elite sport is most appropriately expressed as prolonged underperformance and is identified by following symptoms:

• Sub-optimal performance during training and games
• Disturbed sleep pattern / difficulty sleeping
• Raised resting heart rate
• Loss of appetite and weight loss
• Reduced physical capabilities such as lowered maximum oxygen consumption ( O₂ max) or dynamic strength
• Depression and lack of motivation / drive to train and play
• Frequent upper respiratory tract infections

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Figure 1: How differing training pathways can lead to performance enhancement or overtraining

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Strategies to prevent overtraining

Elite junior soccer players in the professional development squad are often required to play in excess of thirty competitive games during a season; with performance in these games going along way to determining if they are offered a lucrative professional contract! Furthermore, as the development of home-grown talent can be of a high asset value for a club, either as a player or a saleable commodity, strategies that can be employed to prevent the occurrence of over-training are taking on added significance.

Strategy 1: Monitoring Physical Loading

Fatigue development, whether it be caused by disturbances in metabolic, neural or structural homeostasis, is ultimately created by the physical loads placed upon players from training and competitive games. As soccer is a high-intensity intermittent exercise that consists of repeated dynamic actions while running considerable distances, several indicators of physical load should be considered if a true reflection of the stresses being placed upon a player is to be achieved.

*Internal loading

The analysis of heart-rate responses to training provides a measure of the internal or cardiovascular loading placed upon players. This parameter is of importance as research has shown that spending a certain period of time above 85 or 90% of heart rate maximum (HRM) produces significant improvements in both aerobic capacity )VO2max) max and the amount of high-intensity distance performed during a game⁽²⁾. The use of such data has led many sport scientists setting an optimum number of minutes players must spend per training week above 85% HRM that will improve or maintain fitness, while preventing the occurrence of overtraining. Such target minutes are often aligned specifically to a player’s position and cardiovascular responder type.

*External loading

Although heart rate analysis provides an indication of internal stress it often does not reflect the external loading placed upon a player, as many soccer-specific activities such as accelerations/decelerations, turns and tackles are very intense but short in duration. Consequently, many teams now employ GPS technology to monitor the amount and type of physical activities players perform to ensure optimum physical status is maintained.

The importance of considering both internal and external loading was highlighted in a study by Casamichana and colleagues where large discrepancies between the internal and external loads provided by different training practises were noted⁽³⁾. The researchers observed that game formats with small player numbers, while providing a large internal load, do not involve high numbers of sprints and high-speed runs due to the nature of play and pitch size used. Alternatively, when player numbers and pitch sizes were increased, the internal load was reduced, reflected by less time spent above 85% HRM, whereas parameters of external loading such as distance covered at a high-intensity were significantly greater. Such data indicates that to gain a holistic measure of the physical loading placed upon players (and thus prevent overtraining), measures of both the internal and external loading must be obtained.

*Psycho-physiological loading

While data from heart rate and GPS technology is a great tool to objectively assess a player’s training load, the recording of more subjective psycho-physiological measures provides an insight into how players perceive their physical status. Such data is invaluable when detecting the onset of fatigue, as one of the most common symptoms is a feeling of lethargy and a reduced desire to train or play. In specific cases, these psycho-physiological measures can highlight players who have started to find the training load too high - even though the objective data does not indicate any physical concerns.

It is possible that the combination of internal, external and psycho-physiological indicators of physical stress provides the clearest and most robust measure of training load. Such an approach allows sport scientists and conditioning coaches to precisely determine which aspect of loading needs targeting to ensure a player- or indeed any athlete - stays in optimal physical condition and prevent the occurrence of over-training.

Strategy 2: Programme design

In sports such as soccer, which have long competitive seasons, the implementation of periodized training plans are a key strategy in the prevention of fatigue occurrence (see this article for an in-depth look at periodization). An effective periodized training plan will provide players with the correct balance of overload and recovery to allow for the continued development of physical capabilities in synergy with enhanced performance. Within elite sport, the most appropriate periodisation approach tends to provide a non-linear progression in training stress to ensure periods of overload are not performed for too long and are always followed by a recovery or de-loading period. Periodized training plans are typically broken down into four levels:

1. A macro-cycle is an overview of the training plan, often relating to an entire season or training year.
2. A macro-cycle should then be divided into smaller periods called meso-cycles that often last from 4-6 weeks, and have a specific focus or area of fitness to develop (see figure 2).
3. Each meso-cycle then contains micro-cycles, which often relate to a training week, and contain specific detail of the training activities and loadings.
4. Within each micro-cycle will be the training sessions that are to be performed, with specific content of what exercises the player will undertake.

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Figure 2: Example of a non-linear progression in training load for a six week meso-cycle

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In relation to soccer, it is necessary to not only make training plans periodized but also multi-disciplinary in nature so that they are time efficient, often incorporating two training modalities within one programme. For example, by training a player’s metabolic systems within technical/tactical coaching practises additional physical conditioning sessions do not have to be performed to enhance aerobic/anaerobic capabilities. The net outcome of such an approach is a reduction in training volume, something that will ultimately lower the training load.

An interesting study conducted by sport scientists at an English professional soccer club demonstrated that a non-linear progression in training load over the course of a season can be achieved within technical/tactical coaching via the strategic selection of game format and game duration to control intensity and volume respectively⁽⁴⁾. Heart rate and GPS data collected from various small-sided practises was used to categorise game formats into intensity bands dependent upon the overall physical load they imposed upon players. With such data the practitioners were then able to design a periodized training plan that developed the player’s capabilities while providing a non-linear progression in training load via the selection of appropriate game formats. An example of the loading bands is presented below in figure 3.

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Figure 3: Small-sided game formats classified into loading bands for the design of periodized multi-disciplinary training programs

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Strategy 3: Routine physical/physiological measures

The routine measurement of certain physical parameters provides information regarding the body’s physical status, which if applied correctly, can be used to detect reductions in physical performance related to the development of chronic fatigue. As the number of measures proposed for the detection of fatigue are hugely varied, below is a summary of the tests that offer invaluable information regarding a player’s physical status. These are relatively non-invasive and practical to conduct within the hectic timetable of a professional soccer academy.

1. Tests of neuromuscular function

As maximal intensity activities such as sprints and jumps challenge the body’s capability to produce co-ordinated actions that involve high levels of power output, several practitioners have promoted their use as a measure for detecting reductions in neuromuscular function. Interestingly, a study conducted in Sweden noted that following a competitive soccer game, sprint times returned to pre-game levels significantly quicker than counter-movement jump height⁽⁵⁾. The authors suggested that the greater mechanical complexity and involvement of the stretch shortening cycle of the counter-movement jump makes it a more sensitive test of neuromuscular fatigue than a more simplistic straight line sprint.

The size of the reduction in jump height that indicates fatigue development is still unclear. It would be sensible to consider any measure in relation to the stage of the season that it is being taken. For example, during pre-season when players will experience fatigue due to concentrated periods of high volume and high-intensity training, neuromuscular function will be inhibited due to the necessary occurrence of over-reaching as the physiological systems are intentionally overloaded. In contrast, during the latter stage of the competitive season when training load is tapered, it has been suggested that a continued reduction in neuromuscular function of more than 3% might be a cause for concern^(6). The simplicity of jump tests lends them to being performed on a daily or weekly basis, providing sport science practitioners with instant feedback on the neuromuscular status of their players.

2. Metabolic capability

As mentioned in a previous section, over-training has also been shown to reduce a athlete’s endurance or metabolic capabilities. Although measures of VO2max have been most commonly used to highlight a reduction in this area of performance, the measure of aerobic capacity has previously been shown to be insensitive to changes in the training status of elite soccer players. Therefore, more specific measures of soccer fitness such as the ‘YoYo intermittent recovery test’ (YIRT) provide a more valid indicator of reductions in intermittent running capability.

As the YIRT stresses both aerobic and anaerobic metabolic systems it should be used on a less frequent basis the jump test, possibly once per meso-cycle within the periodised training plan. As the distances run in the YIRT and competitive games are positively correlated, performance of the YIRT provides a clear indication of whether a player’s high-intensity running capability is at the level expected/desired for optimal game performance. Any inhibition of the body’s metabolic systems due to fatigue would have a negative impact on YIRT and hence games performance. 

3. Hormonal changes

Technological advances have now made it possible to quickly and accurately detect changes in hormone levels due to heavy and prolonged training loads. A common measure is the testosterone to cortisol (T:C) ratio obtained from a saliva sample. Testosterone is associated with muscle growth and repair; in contrast cortisol is a marker of physical stress. Therefore, any fall in the T:C ratio suggests the body is moving from a state of anabolism (growth) to catabolism (break down)⁽⁷⁾. As anabolism occurs primarily during recovery periods, such a change in this ratio indicates the athlete needs to undergo a period of rest and rejuvenation. Interestingly however, a lowering of the T:C ratio also occurs during the process of over-reaching, which as discussed previously is often a condition elite players must experience if they are to achieve subsequent performance improvements. It might therefore be advisable therefore to interpret T:C ratios with caution and only accept very low T:C ratios as a sign of overtraining.

4. Psychophysiological monitoring

Measures centred on how a player perceives their own physical status are easy to collect, inexpensive but yet provide invaluable data regarding the negative impact the occurrence of overtraining can have on the willingness to train at the necessary intensity. Any issue that is not addressed will have a subsequent negative impact on a player’s physical development, as a reduction in training intensity will not stress physiological systems sufficiently to maintain fitness.

The collection of ‘readiness to train’ scores is an effective yet simple strategy. Players are often asked to rate from 1 to 5 how physically prepared they feel for the forthcoming days training. Scores of below 3 are a cause for concern and can be investigated further to determine if it is reduced sleep quality, appetite, muscle soreness/stiffness, tiredness/lethargy that is responsible for this perceived physical state. If monitored daily, it is then possible to determine if any subsequent changes to training load have a positive impact on how the player feels physically.

References

1 Br J Sports Med 1998; 32: 107-110

2 Med Sci Sports Exerc 2001; 33: 1925-1931

3 J Str Con Res 2013; 27 (2): 369-374. 2013.

4 UKSCA Professional Summer 2013: In Press

5 Med Sci Sports Exerc 2008; 40: 372 – 380

6 Neorol Clin 2008; 26: 181-194

7 Med Sci Sports Exerc 1995; 27: 231 - 237