Overtraining and Performance Deterioration: Knowing when to take a rest day

It is universally agreed by sport and fitness professionals that overtraining is a necessary requirement in order to achieve the relevant physiological adaptations for peak performance. However, when prescribed in inappropriate quantities a deterioration in performance can be provoked. This article considers the impact of overtraining on the psychological and athletic state of an individual, highlighting the importance of various themes presented in my previous blogs.

Overtraining can be defined as a cycle of training whereby the athlete is exposed to excessive maximal capacity training loads. If this training cycle proceeds without adequate rest, a reduction in workload or in conjunction with psychological/physical stressors then overtraining syndrome (OTS) results and subsequently a deteriorated performance is seen.

At present there is no single test that can be utilized to diagnose overtraining, its recognition requires the identification of a number of stress markers which remain elevated despite a period of recovery. Stressors that may be observed include:

•          Diminished skeletal muscle glycogen stores
•          Aerobic efficiency deterioration
•          Suppressed immune system
•          Depression
•          Distorted sleeping pattern

These parameters should be regularly screened for alteration by sport professionals, this will ensure that the short term fatigue related with overload is not confused with the chronic fatigue generated by overtraining.

Numerous studies have taken place to review the effects of overtraining on physiological and psychological functioning, one of which observed that mood state disturbances increase in a dose-response fashion to the training stimulus. These fail to return back to baseline levels even after a significant reduction in training load. It has also been reported that 80% of ‘stale’/overtrained athletes are clinically depressed, substantially affecting other aspects of an individual’s life and overall wellbeing. Alternative research has also shown that 60% of female and 64% of male elite long distance runners have experienced at least one bout of staleness within their running careers, whereas this fell to 30% in highly trained sub elite runners (Morgan, O Connor, Ellickson and Bradley 1988). It is also thought that once staleness is experienced subsequent episodes are more probable, thus emphasising the need for the observation of stress markers in athletic populations. Failure to identify key characteristics may lead to premature retirement from sport, increased injury risk or greater susceptibility to illness.   

It has been argued that a high training volume coupled with insufficient rest will produce muscle, skeletal and/or joint trauma. Such trauma will result in the activation of circulating monocytes by injury related cytokines that produce systemic inflammation, this inflammatory response can trigger the symptoms of diseases such as stroke, heart attack and arthritis. The elevation of cytokines within the circulation also directs a response known as ‘sickness behaviour’, which by means of the central nervous system stimulates negative mood and behavioural changes. In addition, liver function is adjusted to support greater gluconeogenesis (the generation of glucose) alongside de novo synthesis of various proteins and it is this hypercatabolic state that results in muscle wastage. Theoretically meaning that the body’s primary focus is upon survival/recovery, as oppose to the adaptation that training aims to elicit. With regard to immune function, a decrease in glutamine concentration contributes to immunosuppression as it acts as a key fuel for immune system cells.  

As a result of these biological responses it is common for overtrained athletes to present a deteriorated mood state, typically complaining of sleeping disorders, lack of motivation and ‘heavy legs’. An impaired anaerobic performance and lactic acid threshold has also been observed, causing a reduction in the time to exhaustion during high intensity endurance exercise.  

For the prevention of this decline in performance it is essential that training is periodised and tailored to match the Profile of Mood States (stress levels) of the athlete, as well as tapering training prior to competition. These practices should be coupled with adequate carbohydrate ingestion to fuel and recover from physical activity, ensuring the maximum amount of energy is available for exercise. It is also vital the training is abstained from following periods of illness, high stress and extreme environmental conditions for the maintenance of motivation. 

With professional and amateur sporting calendars now including events all year round it is fundamental that athletes of all abilities allow for adequate rest within their regimes. Research clearly documents profound affects to physical and psychological health if individuals fail to do so, these may ultimately lead to severe injury, depression or performance decline. 

The Taper: Physiological Peaking and Optimal Athletic Performance

It is common practice for elite and recreational athletes to spend months, perhaps even years training in preparation for a specific sporting event. However, the physiological and arguably the psychological gains achieved by an intense training regime are useless if the exerciser does not conduct an effective taper.

The first article of this month discussed the importance of a long term training programme, the current article will serve well to complement the previous issues raised and ensure even more refined physiological peaks are achieved. The taper is a fundamental element to sporting preparation and can be characterised as a mesocycle, within which the training stimulus sees a significant reduction. This may be achieved in a linear or nonlinear fashion. The aim of this practice is to minimise any fatigue accumulated during prior training, whilst preventing the loss of relevant biological adaptations. Therefore highlighting the need to maintain training but at a reduced level.

The taper should be exclusively tailored to an individual’s preferences, as any reduction in training will also cause profound psychological effects to occur. Such psychological stressors are due to the absence of a structured lifestyle and increased time to over think performance, both of which account for a greater pre-competition anxiety level that can be detrimental to performance.

There are distinct patterns to tapering, these include a step taper, linear taper or exponential taper which involves a fast or slow decay of the training stimulus. During a step taper a sudden, standardised reduction in training can be observed and lasts for the full taper length. Alternatively, a more gradual decline in the training load can be seen in a progressive linear taper. Lastly, an exponential taper may be implemented, whereby a fast constant of decay elicits a rapid reduction in training load. On the other hand, a slow decay allows for a gradual training load reduction. The graph below displays these taper variations and the training load reduction one can expect to observe throughout its duration.

Current research indicates that a fast decay taper may enhance athletic performance better than a slow decay, as this provides the athlete with more time to overcome accumulated fatigue from the final weeks of an intensive training regime. It is also thought that an advanced reduction to training followed by a subsequent increase could further optimise performance. The reasoning behind this practice is that the athlete would be able to take advantage of a reduction in fatigue, effectively responding to training carried out during the taper.

The effects one can expect from an effective taper include –

•         Hypervolemia, this is an increase in blood plasma albumin content which provides the mechanism to metabolise greater amounts of fat.
•         An increase in red blood cell production, meaning oxygen carrying capacity is greater and improvements to VO₂ max can be expected.
•         Restoration of skeletal muscle and liver glycogen reserves, this is particularly prominent when coupled with appropriate nutritional techniques such as carbohydrate loading.
•         A decrease in total mood disturbance.
•         Increased muscular strength due to a greater maximum shortening velocity.

As a result of the physiological benefits brought about by an effective taper, the mean expected improvement to performance time is approximately 3% (Mujika and Padilla, 2003). This may seem like a fairly modest enhancement, however it could reduce one’s half marathon time from 1:30 to 1:27, decreasing the average running pace per mile from 6:52 down to 6:38.

Finally, in order to achieve an effective taper a reduction in training volume should be seen for a duration of two weeks, the intensity and frequency of this training should be maintained to at least 80% of the pre-taper levels. This ensures the quality of training is not compromised but sufficient recovery time can still occur. A fast decay, nonlinear taper design will also mean no negative psychological responses occur that have often been associated with step designs.  

A Sports Training Phenomenon: The Relevance and Versatility of High Intensity Interval Training (HIIT)

 It is well known in the world of sport and exercise that regular participation in endurance training causes improvements to performance in activities that rely mainly on aerobic metabolism. This is largely due to adaptations that allow for greater oxygen transportation and the subsequent utilization of the more efficient energy fuel, fat. On the other hand, high intensity anaerobic training is generally perceived to have less of an impact upon aerobic capacity and oxidative energy metabolism. However, various publications have shown that regular involvement in high intensity interval training (HIIT) for at least 6 weeks can increase VO₂ max and endurance capacity. Much of the recently published evidence also suggests that these biological adaptations associated with aerobic performance enhancement can be obtained more rapidly via HIIT. The current article will present the recent findings regarding speed endurance/high intensity interval training and discuss its relevance for aerobic performance enhancement.

High intensity interval training can be defined as repeated bouts of high intensity exercise (≥90% VO₂ max) lasting between a few seconds and a few minutes, interspersed with relatively longer periods of rest or low intensity active recovery. The length and nature of this recovery period is very much dependant on the athletes training aims.

Several studies have been carried out to investigate the effects of a HIIT regime; one remarkable finding by Burgomaster et al. (2005) was that despite a dramatic reduction in training volume, vast improvements to aerobic performance were seen when eliciting a high intensity protocol. They found subjects could maintain a fixed submaximal work rate for double the length of time (from 26 to 51 minutes, cycling at 80% of pretraining VO₂ max). These results were achieved after just six HIIT workouts, whilst the control group displayed no alteration in performance.
In another study, conducted by Gibala (2006) the experimental subjects performed a generic HIIT protocol whilst the control group carried out six continuous cycling sessions (65% VO₂ max, 90-120 minutes∙d⁻¹). The total training time completed by each group was 2.5 and 10.5 hours respectively, meaning that the HIIT training group saw a 90% reduction in training volume. Although significantly different in almost every sense of the FITT principles(frequency, intensity, time and type), the two protocols attained virtually identical physiological alterations.

Such a markedly improved aerobic performance can be accounted for by the following biological and metabolic changes:

•       Increased resting glycogen content in the skeletal muscle and liver which can be utilized as an energy fuel.
•          A greater total number of muscle glucose transporters, enabling more metabolic fuel to enter the blood and reach active muscles.
•          Increased density of muscle capillarization, providing the network to transport oxygen and nutrients such as liver glycogen to the working muscles. This also allows for the removal of the fatiguing waste product H⁺ ions, associated with lactic acid and a lowered intramuscular pH that leads to a decline in muscle contraction strength.
•          Speed endurance not only increases the presence of glycolytic enzymes involved in anaerobic metabolism, but also causes greater concentrations of beta oxidation enzymes (citrate synthase and cytochrome oxidase). These are responsible for the metabolization  of fat , thus sparing the body's limited glycogen stores and reducing lactate production.
•          There is an increase in the amount of potassium ions pumped back into the cell, limiting its accumulation in the interstitial fluid and therefore delaying progressive membrane depolarisation. This serves to maintain action potential amplitude - consequently delaying the onset of fatigue.
•          Increased  VO₂ max, enabling a greater aerobic endurance performance.
•          Finally, a greater  buffering capacity of lactate has been observed due to HIIT. More H⁺ transporters means that vast amounts of lactic acid's associated H⁺ ions are able to leave the muscle and move into the blood. Here they combine with bicarbonate to give carbonic acid. When carbonic acid dissociates its products of carbon dioxide and water can simply be exhaled, causing no negative effects to athletic performance.

These adaptations have significant implications in enhancing endurance performance. Firstly, running economy has been seen to gain considerable improvement, this means less energy is required to run at the same velocity. Furthering this point, a decreased energy requirement will allow for the already increased glycogen reserves to be maintained even longer. In addition, faster VO₂ kinetics at the onset of physical activity enables oxygen to be utilized faster for aerobic metabolism. As a result there is less break down of the body's anaerobic reserves and a reduction in metabolite (lactate) accumulation.

To conclude, it is the practical applications of HIIT that are of primary concern to elite athletes and recreational exercisers. It is known that highly endurance trained athletes find it increasingly difficult to achieve further biological adaptations through continuous endurance training alone. However, it has been observed that HIIT can improve endurance performance in already trained aerobic performers by increasing  their VO₂ max and running economy. Furthermore, implementation of this efficient training method will allow for more time to be spent on technical/tactical skills training.

On the level of recreational exercise participation and exercise prescription the most common barrier to physical activity is a lack of time, with many adults even failing to meet the minimum exercise guidelines. The innovations of HIIT could significantly contribute to combating this problem as identical adaptations from prolonged endurance training are obtained in a third of the time.

"I do it as a therapy. I do it as something to keep me alive. We all need a little discipline. Exercise is my discipline" - Jack LaLanne

Long Term Training Plans: Traditional vs Block Periodisation

The periodisation of training can be explained as a division of the entire season or year into smaller, more manageable periods of training blocks. The traditional approach to this training organisation was propose five decades ago, originating in Eastern Europe until spreading West and achieving a virtual monopoly over the way in which sporting professionals devised annual training regimes. However, gradually contradicting training concepts came to light which began to modify the way in which coaches approached  competition preparation, this is known as block periodisation. Today, the vast majority of sporting populations now implement this training structure with considerable athletic benefits being produced that are supported by a variety of journal and professional publications.

Within a traditional periodisation design the following hierarchy of training elements exists:

•             Macrocycle - May range from four years (Olympic preparation), to an annual cycle or several months.
•            Mesocycle - Consists of multiple microcycles, lasting several weeks.
•            Microcycle - Often a week long and is formed of multiple workouts.
•            Workout - Can last up to several hours, any break longer than 40 minutes separates one workout from another.

Ultimately, all macrocycles will focus upon a clear goal, whether this is attaining a personal best or winning an Olympic gold medal.  In a more recreational sense, the aim of an individuals macrocycle may be to reach their goal weight or complete a sub four hour marathon for charity. The macrocycle is then divided into three distinct phases, the first being the preparatory phase; whereby the focus is more generalized in order to improve the athletes basic components of fitness such as aerobic capacity. Secondly, the competition phase, is far more event specific and training would be tailored towards the athletes sport or position with a team. It is possible that this phase will also be interspersed with qualifying rounds or warm up running events for a prospective charity marathon runner. The third and final distinct phase is the transition phase, here an active recovery is completed following the major athletic event. It is vital that training volume is significantly reduced but does not cease completely, this will ensure that the athlete does not enter a state of detraining or experience burnout. Meso and microcycles fall next in the training hierarchy, often the aims of these are to perfect a sport specific technique or develop an aspect of fitness such as speed endurance. Lastly, workouts are the primary building block of any macrocycle, where performance is practically developed and the aims are fulfilled.    

There are aspects of the traditional periodisation model that are still applicable to sport training today, such as the use of relevant terminology and distinction between generalised and sport specific preparations. However, due to a virtually year long athletic seasons and severe time pressures many aspects of this method are unrealistic.

The first of four key drawbacks to traditional periodisation is its inability to give way to multiple physiological peaks that are vital to elite level sport. Numerous peaks in biological adaptations require a radical remodelling of long term training plans, the following three factors will explain why this is so. The traditional design of periodisation involves prolonged mixed training which research suggests results in several negative consequences; specifically the increased secretion of creatine phosphokinase alongside various stress hormones. Thus indicating excessive fatigue,  which may lead to staleness, burnout and ultimately a chronic overuse injury or dropout. It is also apparent that mixed training produces significant performance enhancement during its initial phases, especially among beginners. However, this soon plateaus often with a stagnation or decline in performance following. Furthermore, if this exhaustive mixed training is to last between three and five weeks a profound stress response is caused, this will significantly increase the athletes risk of overtraining or an overuse injury.  

Additionally, multi targeted  training that traditional periodisation encompasses is highly incompatible, often producing conflicting biological responses. These potentially eliminate gains made by one training aim through carrying out exercise aimed at other targets, this time could be better spent training  for a single physiological adaptation. Finally, with regards to high level elite athletes mixed targeted training often does not provide a sufficient stimulus in order to promote any physiological adjustment. In such high performance athletes the required adaptations are so specific that a highly concentrated workload is required to provide an adequate stimuli for their progression. Something that is simply unobtainable with intensive mixed training and may even bring about a decline in performance.

Within the last 30 years the world of sport has seen dramatic changes that account for the radical remodelling of traditional periodisation. Due to the formation of global sporting governing bodies there is now greater opportunity for competition and leagues than ever before. As a consequence multi physiological peaks are necessary, a requirement the new approach of block periodisation can accommodate. Because of this many of the previously seen training periods have been replaced by competition performance, this considerably reduces the training volume and so only focuses on a single key aim during performance preparation. Not only will this be of benefit to the individual physically by allowing appropriate recovery time for maximal energy levels, but also psychologically by decreasing the risk of overtraining that often leads to chronic stress and a lack of motivation.

A further consideration for coaches and exercise leaders is that sporting performance within any club or organisation manifests a wide variety of abilities. In the case of intense mixed training only a minute number of athletes will be developed simultaneously, highly concentrated training on an individual basis can only be developed consecutively - not concurrently.

The general foundations of block periodisation consist of all mesocycle training block and compared with traditional methods are greater in concentration, specificity and manageability. These mesocycle blocks can be further divided into three types, the first of which is the accumulation block. Accumulation targets the masses, intending to enhance basic performance components such as muscular strength and aerobic endurance. It is the longest of mesocycles, lasting two to six weeks. Next transmutation, which typically lasts two to four weeks, targets sport specific techniques, muscular endurance and tactical elements. Finally, realisation sets to model perfect competitive performance whilst reducing the training load prior to competition. This phase also allows for an active recovery alongside controlling emotional stress pending competition, its typical duration lasts 8 to 15 days. 

It is known that the accumulation mesocycle produces the longest training residuals, followed by the transmutation and realisation mesocycle blocks. This provides the basis for the optimal relationship between training effects in order to facilitate athletic performance significantly for varying sporting abilities. Therefore activating general adaptations which amplify the body's hormonal, metabolic and protein synthesis responses.
Conversely, during mixed training stress reactions are more prevalent, suppressing the regulation of hormonal and metabolic homeostasis. Subsequently leading to a dramatic deterioration in the fitness of sub elite and elite athletes, primarily a reduction in VO₂ max, the anaerobic threshold and maximal muscular strength. Whereas the modified periodisation ensures the correct interaction between training loads to exploit maximal physiological adaptations.

"If you train hard, you'll not only be hard, you'll be hard to beat" - Herschel Walker