12 weeks of chemotherapy is equal to a decade of physical decline in terms of cardiorespiratory fitness.
Cardiorespiratory fitness is significantly impacted by cancer and its treatment. Chemotherapy reduces cardiorespiratory fitness. This can be further impacted by thoracic radiation causing fibrosis to the lungs & cardiac abnormalities. A reduction in red blood cells and haemoglobin negatively impacts cardiorespiratory fitness. Combine this with sedentary behaviour and you have a very deconditioned person which then effects quality of life.Cardiorespiratory fitness is a predictor cardiovascular disease mortality and all-cause mortality.
Cardiovascular exercise has been shown to reverse this deconditioning process, even during chemotherapy. Many studies have been able to stop this decline in fitness. E.g. Courneya in 2007, in a randomised control trial (RCT) was able to stop the decline of VO2 peak through aerobic training in women undergoing chemotherapy for breast cancer and Segal in 2009 in another RCT used resistance & aerobic exercise in men undergoing radiation therapy with or without ADT for PC, also stopped the decline in VO2 peak. One study (Jones LW, 2011) produced an increase in cardiorespiratory fitness. He used aerobic interval training with progressive intensity in women undergoing chemotherapy for breast cancer. He achieved an 11.8% increase in cardiorespiratory fitness over the intervention period.
Lakoski, S. G