There are strains of mice in the lab that can run for what seems an endless amount of time. If I happened to be a mouse in a lab I would not be that mouse. My life has been peppered with periods when I have been physically active with sports and exercise, but with time and a changing schedule I often find it difficult to maintain this level of activity. However, it is clear that in my fluctuating activity I am healthiest when I am active.
Although my experience with improved health through exercise is only anecdotal, several studies have investigated the benefits of exercise in those with cystic Fibrosis (CF). One researcher, Courtney Wheatley, in an introduction to a recent study explained that, “the systemic therapeutic benefits of exercise in CF are well known, demonstrating the ability to reduce the characteristic 2-3% annual decline in pulmonary function, increase respiratory muscle endurance, improve exercise tolerance, aid in facilitating sputum clearance, increase aerobic capacity, and result in improved survival for individuals with CF who have higher aerobic fitness.”
To better understand the benefits of exercise, it is important to understand the role ion regulation plays in perpetuating the symptoms characteristic of CF. In a healthy lung, a gradient of Cl- and Na+ exists outside the cells in the airways, which draws water through the cell to hydrate the surface. This water, part of the airway surface liquid (ASL), helps the lung move mucous through mucociliary clearance.
In CF, however, the surface of the airways becomes dehydrated due to an improper ion balance. One reason for this imbalance comes from the fact that the CFTR, which serves as a chloride channel, often has severely reduced function, preventing the passage of Cl- out of the cell. A second reason is that another ion channel, the epithelial sodium channel (ENaC), becomes hyperactive in CF and reabsorbs Na+ into the cell, away from the cell surface. The resulting reduction in Cl- and Na+ in the airways prevents the flow of water which inhibits the movement of mucous out of the lung.
In recent years, increased focus has been put on ameliorating the improper ion balance in CF with the creation a suite of novel CF drugs, such as Kayldeco and Orkambi, but it is being slowly revealed that exercise may also help to improve ion balance through reducing ENaC activity and promoting the calcium activated chloride channels (CaCC), which help to promote increases in Cl- and Na+ out of the cell, hydrating the airways of the lung.
A recent study published in Respiratory Medicine by Courtney Wheatley and colleagues have contributed more evidence for the benefits of exercise in CF at the cellular level. The study observed that “at least in the short term, moderate exercise can provide similar benefits for mediating Cl- efflux as their standard medication albuterol,” which is a standard bronchodilator used in CF healthcare and treatment.
The study “sought to determine if exercise could provide comparable improvements in ion regulation in the CF lung as albuterol, measured using exhaled breath condensate (EBC) collection and nasal potential difference (NPD).” Investigators followed 14 volunteers with CF and 16 healthy volunteers and measured their EBC and NPD levels, used as a measure of ion regulation, 60 minutes after exercise or after albuterol administration alone. They found that there was no significant difference in the net increase in EBC Cl- measured after administration of albuterol compared to the EBC Cl- after the subjects completed exercise.
The authors, in conclusion, noted the possible application of the findings within those with CF. “What is known is that individuals with CF who are more active have a better survival, and participation in exercise has been shown to improve measures of clinical status such as FEV1. So on its own or following a single bout, the increases observed in EBC Cl-, used as an indirect measure of Cl- flux, may not be enough to alter the clinical phenotype, but a habit of exercise and its potential to help ameliorate some of the impairments in ion regulation are likely clinically significant.”
It seems then that infrequent exercise is not sufficient to provide health benefits for those with CF, but it is habitual exercise consistent over time that will improve CF health outcomes.
I am the first to chafe against a set routine of calculated exercise, but I cannot deny that the times when I have been loyal to such a routine is when I have experienced my greatest health. When considering an exercise plan, as I often try, it should be noted that exercise does not have to be 30 minutes four times a week when you kill yourself on a treadmill; it can be simply inviting an active lifestyle in which you take part in activities you enjoy, which could range from dance to rock climbing.
For those who have CF and are interested in either beginning or continuing an active lifestyle I would recommend contacting the Cystic Fibrosis Life Foundation, which is a wonderful organization that helps people and families with CF to engage in active lifestyles through grants that pay for the cost of activities from gym memberships to race fees.
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