Want to catch up with the other articles in this series?
Part 1: What is the impact of endurance training on human lifespan?
Part 1.1: What is VO2max?
Part 2: What are training zones?
Part 2.1: How do muscle fiber types correspond to training zones?
Part 2.2: Training zones 1, 2 and 3
Part 2.3: Training zones 3, 4, 5 and 6
Part 2.4: Moderate intensity vs. high intensity exercise
Part 3: By which mechanisms does exercise delay aging and prevent chronic disease?
Part 3.1: What are the cardiovascular adaptations to endurance training?
Part 3.2: What are the metabolic adaptations to endurance training?
Part 3.3: Can exercise prevent or even treat cancer?
Part 3.4: How does exercise impact the immune system?
Part 3.5: Exercise as a therapy for neurodegeneration and conclusions
Can exercise prevent or even treat cancer?
Epidemiological evidence suggests that physical activity may reduce the risk of mortality for breast, colon, and prostate cancers by 40-50% in those with high levels of physical activity compared to those with low levels.
Strong evidence suggests that physical activity reduces the risk of breast, colon, endometrium, bladder, stomach, oesophagus, and kidney cancers, and there is moderate evidence for a link with reduced risk of lung cancer. Limited evidence suggests a relationship with reduced risk of prostate cancer, while the evidence for other types of cancer is limited due to a lack of research in these areas.
P53 Protein in Exercise
P53 is a protein that plays a role in various processes related to substrate metabolism and mitochondrial biogenesis. It is known as a tumour suppressor protein, and its functions include regulating cell cycle arrest, apoptosis, angiogenesis, DNA repair, and cell senescence. Studies have shown that p53 can be affected by exercise, with some research indicating that its phosphorylation increases after endurance or high intensity interval training (HIIT), while other research suggests that only maximal sprint training has an effect on p53 content. It is worth noting that the regulation of p53 may also be influenced by factors such as the nutritional status of muscle during training. More research is needed to fully understand the role of p53 in endurance exercise and its potential use in cancer therapy.
Figure 3.5: tumour suppressor functions of p53
The regulation of p53 may not only be affected by the intensity of the exercise, but also by the nutritional status of the muscle during training. For example, reduced carbohydrate availability may influence the regulation of p53. It is important to consider both exercise intensity and nutritional status when studying the effects of exercise on p53 and other signalling pathways.
Traditionally, endurance training has involved ensuring high carbohydrate availability in order to provide the necessary fuel for high intensity and volume training. However, in recent years, some research has suggested that deliberately training in low carbohydrate conditions can actually lead to adaptations in skeletal muscle, such as increased mitochondrial enzyme activity and content, increased lipid oxidation, and improved exercise capacity.
This approach, known as "training low, but competing high," involves completing some training sessions in low carbohydrate conditions to promote adaptations, but restoring carbohydrate stores before important competitions. These training-low strategies are thought to work by activating certain signalling pathways and transcription factors, leading to changes in the nuclear and mitochondrial genomes. While the best way to implement "train-low" workouts is not yet known, consuming additional caffeine, protein, and practising carbohydrate mouth-rinsing before and during training may help to maintain training intensity and immune function. It is important to also include training sessions with normal or high carbohydrate availability to avoid impairing the ability to oxidise carbohydrates.
