Benefits of exercise in cancer & comparing high- and moderate-intensity exercise programs

Many toxic substances are released during diagnosis and treatment in cancer patients. These increase disease and mortality rates. According to studies, adjuvant chemotherapy reduces oxygen-use efficiency by causing loss of mitochondrial content and function.

Regular exercise reduces both colorectal cancer incidence and recurrence risk

Colorectal (large bowel) cancersare common worldwide and have high mortality; in our country they are the 3rd most frequent cancers in both women and men. Studies show regular exercise reduces colorectal cancer incidence by % 33-44. Regular exercise during treatment has also been found to reduce recurrence risk.

The “effect of adjuvant treatment on mitochondrial function” mentioned in the introduction occurs through reduced oxidative phosphorylation capacity. This reduction increases skeletal muscle mass loss. Skeletal muscle loss and weight loss are common treatment side effects. Regular exercise is considered among the most effective measures against treatment’s negative effects, reduced mitochondrial function and reduced oxidative phosphorylation capacity.

A study examining exercise’s effects on colorectal cancer found increased cellular activation of “Peroxisome proliferator-activated receptor γ co-activator 1α (PGC-1α)”. PGC-1α activation increases mitochondrial biogenesis (the number of mitochondria), regulates muscle cell types, blood pressure and cholesterol homeostasis, and reduces obesity development. It also regulates muscle growth through “5′-adenosine monophosphate-activated protein kinase” and “MAPK” activation. These effects increase oxidative phosphorylation capacity and prevent muscle mass loss. The study also investigated the effects of two exercise programs.

Participants were divided into two groups:

• One received a high-intensity exercise program. This involved 10 minutes warming up at % 50-70 of maximum heart rate, then 4 minutes cycling at % 85-95 of maximum heart rate, followed by 3 minutes rest, repeated for 4 sets, with total training of 38 minutes.
• The other received a moderate-intensity exercise program involving 50 minutes of cycling at % 50-70 of maximum heart rate.

The data showed that high-intensity training was much more beneficial for oxygen capacity, oxygen-use efficiency, oxidative phosphorylation capacity, muscle hypertrophyand muscle mass gain. Moderate-intensity training was even observed to have no effect on muscle mass gain and fat mass loss compared with high-intensity training. High-intensity training three days weekly is also known to reduce treatment-related fatigue within 8 weeks.