Monitoring Our Way to Good Performance

By Renee McGregor

“Competitiveness is a biological trait that co-evolved with the basic need for human survival.” (Sander Van Der Linden, 2015).

Whilst this can be used in any context, it does explain why we, as runners, are always in search of that next challenge, next achievement and recording our training sessions to use as validation that we are progressing.

However, we also know that while being driven is a positive trait, helping us to lace up our trainers and head out of the door, it can be a little like walking on a tight rope. Stay balanced and you will reap the rewards, but push too far and that same trait, can become dysfunctional and potentially destructive.

A recent article on Run247 (Feb 2019) discussed the rise of ultra races but also how many runners are competing in back-to-back events, giving little thought to the impact it might be having to their body and long-term health.

Can we really use “how we feel?” post-race as a subjective indicator to understand if our body is ready to race again?

I’m a big fan of monitoring: ask any athlete I have worked with and it’s fundamental to my practise. If you really want to get the most out of someone’s performance, you have to understand how their body is responding to their training load.  Only then can you provide them with appropriate nutritional interventions.

So what do I mean when I talk about monitoring? Sleep, yes absolutely. There are numerous studies linking the importance of sleep for recovery but if your body is in a chronic stressed state, either physical or mental, this impacts your body’s ability to have a decent night’s sleep. I also encourage athletes to rate their energy levels (subjective I know) and their motivation to train. This can tell us a lot about their physical and psychological status.

However, I go one step further. My biochemistry and clinical background in nutrition has always meant that I have a real interest in what’s going on within the body.  For this reason, I’m a big fan of monitoring blood biomarkers, or more simply put, a measurement of blood values that can tell us about immune, bone, hormonal health and inflammation and thus their readiness to train and compete.

Looking at specific blood biomarkers can help to ascertain what is really going on within the body. Some of the key values I look at include:


I generally look at hemoglobin (Hb), ferritin (iron stores) and transferrin saturation, which helps to identify absorption of iron from the gut.

It is important to identify low levels, as a deficiency will have a negative impact on appetite, energy and overall performance. It is important to look at all three values for full picture; values of Hb should be 14 or above, ferritin 40 or above and transferrin saturation above 20% in individuals who are very active.

Vitamin D

We know from studies that low levels are very common in the UK due to the lack of sunlight. Deficiency in the general population has been linked to low immunity, low mood and fatigue. This is further enhanced in those of us that are very active also resulting in poor recovery between training sessions and increased muscle soreness.

Vitamin D has a very important role in bone health as it helps the absorption of calcium – acceptable levels for the athletic population should ideally be > 90nmol/l.

The Thyroid

The thyroid gland is integral to our health and performance on so many levels. These levels are of particular interest to me when I’m monitoring runners and endurance athletes. I will look at TSH (thyroid stimulating hormone), Free T3, LH (luteinising hormone) and oestrogen/testosterone.

When we over reach/over train and/or under fuel, we create more stress to the body. This stress has a negative impact on the pituitary gland and thus can dial down our thyroid function.

Monitoring TSH can help identify those at risk, while a low level of T3 will indicate low energy availability and that there is not sufficient energy being taken on board to fuel both training and maintaining biological processes. This in turn can lead to a reduction in the production of the sex hormones. Chronically low oestrogen and testosterone levels will have implications on bone, cardiovascular and immune health as well as overall mood.

C-Reactive Protein (CRP) and Creatine Kinase (CK)

These give us direct information about the level of inflammation in the body.

Whilst exercise will result in raised levels, it can be a good indicator of recovery rates after races but also provides the relative risk of over training. This is definitely something I look for when a runner is looking to go back to training straight after racing. Training with raised levels will increase the risk of injury but also the overall stress on the body.

9am Cortisol

Whilst levels will be highest in the morning, a consistently high level indicates the body is under stress.  This could be lack of recovery, poor sleep, high anxiety levels or poor fuelling. Regardless of the cause, chronically high levels will have negative consequences to our immune and metabolic health.

Additionally, there will be a dysfunction in fat and carbohydrate metabolism which can result in the body preserving energy and holding onto visceral fat.  This is why in some cases, the harder the individual works, the more stress they create but there is no adaptation with regards to body composition or performance.


In most cases, if I’m worried about bone health, the gold standard would be to organise a DEXA scan. However, this is not always possible and looking at certain markers can help to provide some information about bone turn over.

Low Levels of Vitamin D, low levels of oestrogen or testosterone, abnormal TSH and high levels of alkaline phosphatase may all be indicators that bone health is being impacted.

This list is not exhaustive but it gives you an idea of the key markers to monitor in order to progress your training. While some may be available on the NHS, it can be tricky to get everything in this article measured, especially if you don’t really have any medical symptoms. In these cases, I tend to recommend Forth Edge who provide a full analysis and review by an Endocrinologist and also set up recurring tests to help you periodise your training and racing.

Renee McGregor

"Looking at specific blood biomarkers can help to ascertain what is really going on within the body"

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