- 1 Introduction
- 2 Terminology
- 3 Monitoring of load and injury
- 4 Practical guidelines for load management
- 5 References
Over the last few decades sport has become a competitive, professionalised industry. Athletes have to deal with fuller competition calendars and face increasingly higher pressure to stay competitive. Consequently, athletes of all levels as well as their coaching staff are relentlessly aiming to improve performance. Although there are a multitude of factors that can contribute, the main factor athletes focus on is usually their training methods. Training and competition load causes a series of homeostatic responses and adaptations in the human body.  The key factor in training theory is to implement this process of biological adaptation to improve fitness and eventually improve performance. Furthermore, a principal goal in rehabilitation is improving capacity to manage load and this has been discussed in the literature in relation to tendinopathy and cartilage repair. There is also good evidence for load management to prevent illness and over-training in athletes.
Poorly managed training loads in conjunction with the full competition calendar may influence the health of athletes. The balance between external load and tissue capacity plays a significant role in injury and although there are various intrinsic and extrinsic factors involved in injuries, there is evidence to suggest that load management is a key risk factor for injury.
The relationship between load and heath is considered as a well-being continuum, with load and recovery as mutual counter agents. Also, during rehabilitation processes, initially we might consider reducing load to allow pain to settle and allow gentle specific exercise prescription. Later we will gradually increase load by progressing the exercise prescription appropriate for restoring normal function specific for an individual and their disorder as symptoms allow.
The IOC Consensus statement on load management defines load as "the sport and non-sport burden (single or multiple physiological, psychological or mechanical stressors) as a stimulus that is applied to a human biological system (including subcellular elements, a single cell, tissues, one or multiple organ systems, or the individual). Load can be applied to the individual human biological system over varying time periods (seconds, minutes, hours to days, weeks, months and years) and with varying magnitude (i.e. duration, frequency and intensity)."
External load refers to any external stimulus applied to the athlete that is measured independently of their internal characteristics. Internal load refers to the physiological and psychological response in an individual following the application of an external load.
Monitoring of load and injury
Monitoring athletes is essential in order to define the relationship between load and risk of injury in the management of athletes as well as in research. This includes not only the accurate measurement and monitoring of the external and internal loads on the athlete, but also the performance, emotional well-being, symptoms and injuries of the athlete.
Benefits of scientific monitoring
- explaining changes in performance
- increased understanding of training responses
- identifying fatigue and accompanying needs for recovery
- informing the planning and modification of training programmes as well as competition calendars
- ensuring therapeutic levels of load to minimise the risk of non-functional over-reaching (fatigue lasting weeks to months), injury and illness
Monitoring external and internal loads
Different measures of load are available, but the evidence for their validity as markers of adaptation and maladaptation is limited. There is no single marker of an athlete's response to load that consistently predicts maladaptation or injury.
Examples of measurement tools to monitor external loads
- Training or competition time
- Training or competition frequency
- Type of training or competition
- Time-motion analysis
- Power output, speed, acceleration
- Neuromuscular function (eg. jump test, isokinetic dynamometry and plyometric push-up)
- Movement repetition counts (eg, jumps, throws, pitches, serves, bowls)
- Distance (eg kilometres run, swam or cycle)
- Acute:chronic load ratio
Examples of measurement tools to monitor internal loads
- Perception of effort (eg, rate of perceived exertion RPE)
- Session rating of perceived effort (session duration (min) x RPE)
- Psychological inventories (eg, profile of mood states (POMS); Recovery stress questionnaire for athletes (REST-Q- Sport)
- Sleep (eg sleep quality and sleep duration)
- Biochemical/hormonal/immunological assessments
- Heart rate (HR)
- HR to RPE ratio
- HR recovery (HRR)
- HR variability (HRV)
- Blood lactate concentrations
- Blood lactate to RPE ration
Monitoring external load is key to understanding the work completed, the capabilities of the athlete as well as the athlete's capacity. Internal load monitoring is vital in establishing the appropriate stimulus necessary for ideal biological change. It is evident that individuals will respond differently to any given stimulus and that the load required will differ for each individual. There is no "one size fits all" solution.
Practical guidelines for load management
The overall aim of proper load management is to ideally construct training, competition and other load to enhance adaptation and maximise performance whilst also reducing the risk of injury. It therefore, entails the correct prescription of load as well as the correct monitoring and change in external and internal loads.
Prescribing training and competition load
- High loads may have either positive or negative effects on injury risks in athletes. The key factors are the rate of load application and the intrinsic risk profile of the athlete. Athletes respond significantly better to smaller increases and decreases in load, than big variations in loading. Different sports will have different load-injury profiles. Current evidence from sports such as Australian football, cricket and rugby league recommends that athletes should limit weekly increases of their training load to less than 10% or maintain an acute:chronic load ratio within a range of 0.8 - 1.3, in order to maintain in positive adaptation and therefore reduce the injury risk.
- Acute load is the absolute workload done in 1 week and chronic load is the average acute workload done in 4 weeks. The ratio between acute and chronic shows if the acute workload is greater or less than the total workload of the weeks before it
- A acute:chronic workload of 0.5 means that the athlete trained/competed half of what was prepared for the 4 weeks prior
- A ratio of 2.0 means the athlete did twice as much, anything more than 1.5 is seen as a spike in training and could be seen as an injury risk.
- In football it has been shown that playing two matches (ie, less than 4 days recovery between matches), compared to one match per week, increases the risk of injury. It is therefore suggested that football teams should contemplate squad rotations to protect individual players from large increases in match loads which may put them at higher risk of injury.
- There is no "one size fits all" principle. Load should be prescribed or recommended on an individual and flexible basis, as there is a large variation in the time frame of response and adaptation to load.
- The load management in developing athletes should be monitored closely, as these athletes are at higher risk for injury when introduced to new loads, changes in load or difficult competition calendars.
- The prescription of training and/or competition loads should be guided by the variation in an athlete's psychological stressors.
- Adequate recovery sessions should be incorporated after intensive training periods, competitions and travel. Furthermore, care should be given to nutrition, hydration, sleep, rest, active rest, relaxation strategies and emotional support.
- The health of the athlete is paramount and sports governing bodies should consider this when planning their event calendars. Therefore, it is vital that there should be an increased coordination between single-sport and multisport event organisers, and the development of a comprehensive calendar of all international sports events.
Scientific monitoring of an athlete's load is essential for ideal load management, athlete adaptation and injury management in sport.
- Coaches and support staff should invest in scientific methods to monitor the athlete's load and detect meaningful change.
- Always monitor load individually.
- Employ a combination of external and internal load measures relevant and specific to each sport.
- Subjective load measures are useful and coaches and support staff are encouraged to make use of these measures.
- Monitor load by using a comprehensive approach that takes into account interaction with other intrinsic and extrinsic factors such as history of injury, age and sex.
- Special care should be given to the monitoring of an athlete's acute and chronic workload, as well as the acute:chronic load ratio of an individual athlete.
- Frequent monitoring is suggested to enable acute adjustments to training and competition loads.
Monitoring of injury
Monitoring an athletes health can lead to early detection of symptoms and signs of injury, it can aid in early diagnosis and guide the appropriate intervention.
- On-going scientific injury surveillance systems should be employed in all sports
- Monitoring tools should be sensitive to acute and overuse injuries, as well as early clinical symptoms such as pain and functional limitations
- Injury monitoring should be on-going, but at least occur for a period of time (at least 4 weeks) after rapid increases in load.
A great summary on load management is also available at Balancing training load and tissue capacity. by T. Goom, Running physio,2015.
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