Fructose Part 2:  Blunting Aerobic Development

Fructose Part 2: Blunting Aerobic Development

In the November Monday Mindshare we began our three-part series on the topic of Fructose. In Part 1, we discussed the research trends, regarding the over-consumption of fructose and its negative implications for long-term health and well-being.

As noted in part 1, the SFuels RIGHT FUEL RIGHT TIME(TM) approach led by SFuels and Endure.IQ is grounded in the holistic and timely use of all the body's energy systems, and associated substrates including carbohydrates, fats, and ketones.

In this Part 2 of the Fructose series, we'll touch on some specific studies that highlight how the over-consumption of Fructose can possibly 'blunt' the training effect of aerobic exercise. 

Plus further below - we'll give you some ideas on how to avoid Fructose in every day foods, meals and snacks.

As highlighted in November, with Fructose making up 50% of table sugar (sucrose) and being commonly used in foods, it's a highly pervasive food ingredient. For athletes though, there are even higher concerns on the implications of fructose over-consumption.

Firstly, the consumption risk is likely higher for athletes in light of most sports-fueling drinks, gels, blocks, and bars containing high amounts of Fructose, sugar/sucrose, and/or high-fructose corn syrup. Increasingly these are being used beyond workouts and training.

And second, progressive endurance development has much to do with the training stimuli that affects the number (density) and size of mitochondria (the energy factories of the cell). As you will read below, researchers are highlighting that it's inside these mitochondria, where fructose would be directing its negative effects.


Most recently, in late 2022 the peer-reviewed journal of Nutritional Neuroscience published a paper highlighting the impact of higher Fructose consumption on mitochondrial energetics, and cell viability.  As noted in the paper, Fructose rapidly (in 6 hours), and dramatically impacted mitochondrial respiration, ATP production, and reduced the lifespan of the cell.  

A little earlier in 2017, another research team published a paper on assessing whether Fructose damaged Mitochondrial DNA and impacted its repair.  In just 8 weeks, the study revealed how Fructose heightened mitochondrial DNA damage and showed signs of impaired mitochondrial biogenesis (repair) in animals.  The study highlights this could be one reason behind the role of Fructose in metabolic dysfunction.  Another study in 2015, also showed very similar findings on skeletal muscle mitochondria. 

But it was a paper in 2017, that directly triggered our concern about the impact of Fructose on the body's adaptive response to aerobic exercise.  The study looked at a range of genes in the skeletal muscle cell, that are known to adapt to the stress of aerobic exercise.  It was found that Fructose consumption had a blunting effect on the expression of these genes associated with remodeling muscle, in response to the stress of aerobic exercise.   

So, it was studies like these, and the parallel wave of research on fructose and metabolic disease that informed SFuels to formulate its training-racing products without adding Fructose.

So what to do about it?  Besides the use of SFuels in your training and racing, here's our Top 10 Foods to avoid and simple ideas on how to replace Fructose with better options.


1) Divya Lodha et al.  Detrimental effects of fructose on mitochondria in mouse motor neurons and on C. elegans healthspan.  Nutritional Neuroscience. 2022 Jun. 

2) Federica Cioffi et al.  Fructose-Rich Diet Affects Mitochondrial DNA Damage and Repair in Rats.  Nutrients.  2017 Mar.

3) Natasha Jaiswal et al. Fructose induces mitochondrial dysfunction and triggers apoptosis in skeletal muscle cells by provoking oxidative stress.  Apoptosis. 2015 Jul.

4) Natalia Gomes Gonçalves et al.  Fructose ingestion impairs expression of genes involved in skeletal muscle's adaptive response to aerobic exercise. Genes & Nutrition. 2017 Dec.
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