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Phil Cavell: ‘The mainstream press peddles simplistic messages’

Expert bikefitter Phil Cavell examines whether there’s such a thing as too much exercise

Phil Cavell
30 May 2022

If you’re over 45 and seeking high levels of performance then you may well have decamped into one of several exercise realities.

The first is that sustained, high-level exercise is inherently good and more exercise is therefore better. Increased FTP equals increased overall health.



The second reality is that high-level exercise is inherently harmful – it degrades our biological structures like driving in the rain wears out windscreen wipers. You do it anyway because you love cycling and accept the risks.

The third reality choice is one of blissful ignorance. You may assume that exercise is generally good for you but have a nagging suspicion that genetics might be against your best efforts to be healthier.

Don’t be disheartened if you reside in one or sometimes more than one of these realities. The mainstream press often peddles simplistic messages about training hard into middle age, and I’ve fallen into a similar trap by using the terms ‘training hard’ and ‘high-level’ without actually defining them. So let’s do that now.

Long-term effects

Photo: Juan Trujillo Andrades

It’s relatively easy to define sedentary and moderate exercisers – those for whom exercise is incidental to performance.

In cycling terms, moderate exercisers are likely to commute and/or ride up to around 100km per week for leisure, and receive a kaleidoscope of benefits over the sedentary group: up to 50% reduction in cardiovascular disease, 40% reduction of type-2 diabetes, increased protection from dementia, the list goes on.

It’s what happens when you step up from moderate to heavy exercise that provokes controversy.

Sustained, high-intensity endurance cycling causes a ‘five to sevenfold increase in cardiac output’, according to Dr Gemma Parry-Williams and Sanjay Sharma in the review paper The Effects of Endurance Exercise On The Heart.

It is these excessive demands that can remodel the heart over time. The degree and extent of this is a function of the number of years cycled and relative training intensity – increases of 10% LV (left ventricle cavity) and 24% RV (right ventricle cavity) are not untypical, say the researchers.

The veteran ‘athlete’s heart’ also normally has a far lower resting rate than the untrained heart. But there’s more to the picture.

In a 2017 study, 152 masters runners and cyclists (defined as ‘heavy exercisers’, training for least eight hours per week continuously for an average of 31 years) were observed to have an average 60% higher VO2 than a control group of 92 sedentary and moderate exercisers.

Surprisingly, though, these heavy exercisers also had double the prevalence (44% vs 22%) of coronary artery plaques – that is, the build-up of deposits in the artery wall.

If plaques rupture they can cause a myocardial infarction (MI), or heart attack, so it was the plaques that caught everyone’s attention, including the mainstream press, because MIs are the predominant (but still rare) cause of cardiovascular events in masters athletes. But the plaque story is itself nuanced.

Lifelong heavy exercisers tend to have more plaques that are stable and thought unlikely to rupture. Sedentary folk and newcomers to exercise were more inclined to have more mixed morphology or even wholly soft plaques, which contain unstable fatty, lipid-based material that is assumed to be more vulnerable to inflammation and therefore to rupture.

Photo: Juan Trujillo Andrades

So what does all this mean for you as a midlife cyclist? If you’re a long-term exerciser who trains at a high level, you may have cardiac remodelling, which itself may be protective as well as allowing you to perform better than sedentary individuals.

However, even seasoned midlife athletes should review their family cardiac history, cholesterol, blood pressure and any new symptoms with their GP.

The advice for new and returning midlife athletes is more prescriptive and comprehensive, with the minimum being to discuss with your GP what training you are planning, and review the above.

This can all be assimilated into a QRISK score (an NHS algorithm-based risk calculation), plus a cardiac CT/CAC ramp test (or plaque review) depending on your QRISK score.

Better understanding

Photo: Juan Trujillo Andrades

Endurance exercise training is almost certainly beneficial – we adapted over millions of years to perform well in stamina-based challenges.

We can compensate for the current gaps in midlife biology with a thorough understanding of our own personal biology, and from there pick our own point on the duration/intensity spectrum – health and fitness being at one end and pro rider performance at the other.

Remember that dialling further towards the ‘pro’ side should be done for enjoyment, not because we necessarily believe it is good for us.

Oh, and none of this seems to affect female midlife athletes to the same degree as males. Add that to the ‘unknown’ in-tray.

Phil Cavell is co-founder and bikefitter at Cyclefit in London. His book The Midlife Cyclist is available on Amazon (£12.59)

Main image: Danny Bird

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