When we train, particularly on key workouts, we stress our bodies. Our bodies go into panic mode to adapt to that stress. As a result, our bodies become stronger and is better prepared for the next stress that will be placed upon us. This process is known as adaptation. When the stress of a particular workout or accumulation of workouts is greater than our bodies ability to adapt, overreaching occurs which if not controlled leads to overtraining. Unless this process is reversed a performance decrement, illness or even injury can occur.

Modern advances in sports science and technology allow for training and biological data to be readily available that can determine how much stresses our bodies are under. Some of these interventions may not be accessible to all athletes, but some simple strategies can be very effective in allowing us to optimise training load and avoid over-training and its consequences. By listening to our bodies we can control the internal loading and the stresses placed upon it.

A very simple and cost-free strategy is to use a training diary to record key training data and use some subjective markers such as rate of perceived exertion (RPE), quality of sleep, mood and energy levels. When the body is stressed from training or other work/life stressors, a hormone known as cortisol is produced cyclically. This hormone when elevated at the wrong time can keep us alert and awake at night disrupting sleep. It can be at low levels during the day, which can result in feeling tired and in poor mood state. Subjective markers such as outlined above can indicate elevated night-time cortisol and heightened stress.

A standard periodic blood test can be indicative of the stress our bodies are under. Markers such as haemoglobin and serum ferritin when below recommended parameters can suggest low iron stores or anaemia – something common among endurance athletes. This can be due to inadequate iron intake, hemolysis or perhaps inhibited iron absorption.  Poor nutrition timing from consuming foods such as coffee, tea, calcium, zinc and copper, which compete for the same absorption pathways as iron; can inhibit absorption. After hard training, a hormone called hepcidin is released, which blocks the absorption of iron. Therefore consuming iron within an acute period after a workout can prove futile. Other blood markers such as creatine kinase when elevated can suggest muscle damage. White blood cell markers can measure immune system stress.

We can monitor the internal loading of our training sessions by measuring heart rate and blood lactate. When training heart rates for a given workload is higher it can suggest early signs of over-training. If the heart rate is lower towards the end of a mesocycle, it can indicate overreaching which if not controlled can lead to overtraining. With the knowledge of doing a lactate test, taking blood lactate measurements during key workouts can measure metabolic stress and be a sign of overreaching or overtraining. If blood lactates start to accumulate at a given workload, perhaps there has been too much anaerobic interference and the aerobic system and lactate threshold has become destabilised. Another useful tool is measuring heart rate variability (HRV), which can measure the central nervous system (CNS) stress and fatigue. All of these biological tools can allow the athlete or coach to individualise a training programme and ensure the loading is optimal and recovery periods are accurately timed to ensure maximum adaptation potential.

Is it wise to do a hard workout on a given day if your sleep has been inadequate the night before, with training and energy levels at a low level the previous day? Just because it is programmed into the training schedule does not mean it is right to do it if there is obvious stress from training load or other external factors. There is nothing wrong with postponing training by a day or even a few hours to regain lost sleep and ensure that the body is in a more biologically ready state to handle and adapt to the training load more optimally. This can be difficult for athletes training in a group under the one coach and a ‘one size fits all’ programme.

A training programme should factor into account work/study, family and other life commitments outside of training stress. Every athlete responds differently to such stresses. The training must be individualised in so far as possible and a good degree of flexibility must exist in order to get the most out of the programme and ensure performance is optimised. Stress is a good thing in the right doses. But during a period of overreaching, we need to be vigilant and be ready to adjust and implement recovery where necessary. The term ‘listen to the body’ may seem old school and simplistic, but using some simple subjective feedback and biological markers can make this process very effective.