Scientific Principals of Training

Scientific Principals of Training

The Scientific Principals of Training are, as the name would suggest, are a set of principles that underpin training. Understanding of these principals and recognising the trade-offs between different principals helps support effective program design. In this post, I will discuss these principals and how to apply them to your training or patient programs. 

If you have not followed our earlier posts on Strength and Conditioning, check out our introduction here. In our upcoming post on planing, we will use the principals to help guide program development.

I had the pleasure of presenting to a group of physiotherapists working in a hospital setting last week. In this presentation, I referenced these principles. These principles are well understood in the strength and conditioning community. However, it was clear from the blank faces that it was not in this setting. So the following is a summary of the Scientific Principals of Training and why they matter. 

First things first, the Scientific Principles of Training are:

  • Specificity
  • Overload
  • Fatigue management
  • Stimulus Adaption and Recovery
  • Variation
  • Phase Potentiation
  • Individual Differences

You will see some variation in different texts, or different words but the concepts remain substantially the same. Again the importance of these principals is to identify their trade-offs not to promote their rigid application. 


I have said a few times that there are trade-offs in the principles. So what do I mean by that? If we look at principals 2 and 3, Overload and Fatigue Management, we can see that there are circumstances in which these do not align. The training that maximises Overload will fail to achieve Fatigue Management well. Conversely optimising Fatigue Management will not best support Overload. Equally, at times Specificity and Variation will be at odds, as will Overload and Stimulus Adaption and Recovery and multiple other examples of these principals being at odds exist. 

Critically, for each decision that we make in a program, it should be weighed against any opposing principle. How we consider and balance these principles is, in a nutshell, the art of coaching. How we balance these principals is heavily dictated by the context of the athlete’s goals, where they are in their season, work, training and social commitments to name but a few. 


Specificity is the degree to which a training stimulus is related to the sport that is being trained and is the framework around which other decisions in a program are made. At its simplest level, we get good at what we do. Want to squat better, squat more. Want to bench press more, then bench press more.  

Following the principle of Specificity, training should guide the underlying adaptions needed to excel in a given sport or activity and reflect the demands of the activity for which we are training. 


Overload states that training must become progressively more challenging to continue to induce training adaption. How this Overload is reached will determine the resultant adaption. Take a simple example such as squatting, achieving Overload by completing progressively more volume (more sets or more reps) will induce adaptions supporting increased muscular endurance. Conversely, achieving Overload by increasing the weight lifted will result in strength development. 

It is by this directed Overload that we can specify the training adaption that we are aiming to achieve, be it greater mass, strength or power. Fail to progressively Overload, and you or your athletes will not adapt. Overload to aggressively and staleness, missed sessions and injury are the likely results. 

Fatigue Management

Fatigue management is the organisation and planning of training stressors in such a way to maximise training adaption while managing the negative impacts of fatigue. 

At an annual training plan level, planning of training should include not just periods of progressively higher stress but also periods of relative rest or recovery. Fatigue Management is perhaps most recognisable in the offseason where athletes recover following periods of increased physical and psychological stress. However, this periodic offloading or deloading should also form a part of the weekly and monthly training cycles. 

The under application of Fatigue Management helps avoid excessive fatigue, staleness or injury.

Stimulus Recovery Adaption

Stimulus Recovery Adaption or SRA is the process by which training adaption occurs. With a given training session (Stimulus), a variable amount of stress and microscopic damage occurs. Following this, the body undertakes a process of Recovery and Adaptation, resulting in improvement or training adaption. Different training modalities will result in varying degrees of Stimulus and require different time frames for Recovery and Adaption. Compare, the degree of Stimulus from a short walk, versus a heavy sprint training session. The timeframe for recovery and adaption for these sessions will differ markedly. 

More technical skills-based exercises may have shorter SRA curves, compared to heavy strength session. Timing of sessions should account for the impact of ongoing recovery from one session on subsequent sessions. 


The principle of Variation encompasses the strategic changes to training used to support long term training adaption. Variation helps avoid overuse, staleness, or adaptive resistance (think the law of diminishing returns in applied practice) that would occur if we dogmatically followed the principle of Specificity. 

As with each of the principles, the use of Variation will change over the training year. When close to a critical event, limited Variation would typically apply to allow higher Specificity.

Phase Potentiation

Phase Potentiation is the strategic sequencing of training to enhance subsequent phases of training. It comprises a progression from more general to more specific training and finally peaking. The time an athlete will spend in each period is highly athlete dependent upon training age, injury history and status and performance needs. 

In describing the principle of Phase Potentiation to athletes, I often use the analogy of learning to walk before running. Learning to walk is a base skill, that underpins later, more complex, skills such as running. Much like in this example, a more advanced athlete may require less time dedicated to general preparation in subsequent training programs. 

Individual Differences

The principals of training apply to everybody, but the amount to which each affects people differs. The principle of Individual Differences reflects the fact that individuals are well, different.

Individual Differences will be affected by a large number of factors including, age, gender, size, strength, absolute and relative loads used to name but a few. It is important to remember that individual difference will affect the volume, intensity and distribution of work, and exercise selection. However, the general program structure will often be substantially similar despite these differences. 


So there we have a summary of the Scientific Principals of Training. Hopefully, you can use these to inform your training to achieve peak performance and remain injury-free. 

Until next time, happy training. 

Michael Hedger