There is little controversy regarding the importance of exercise to children and adults with cystic fibrosis. In the twenty years since Nixon et al showed that higher levels of aerobic fitness was associated with a significantly lower risk of dying numerous studies have documented the benefits of exercise, including: improved airway clearance, weight gain, improved cardiorespiratory fitness, increased work capacity, improved bone density, increased exercise tolerance, decreased feeling of breathlessness, and improved body image and quality of life. Even those who are awaiting transplantation are encouraged to exercise as tolerated, since studies have shown that exercise both before and after lung-transplant surgery tends to make cardiopulmonary function more efficient, strengthen respiratory muscles, and ensure good bone density.
But perhaps the most significant reason to incorporate exercise in the CF care regimen was shown in the longest published study to date regarding this issue. A three-year home based program including aerobic exercise three times weekly concluded that “pulmonary function declined more slowly in the exercise group than in the control group”.2 Certainly with the exciting prospect of CFTR correctors and potentiators around the corner, it is extremely important to maintain as much lung function as possible until the day comes when CF becomes a controllable disease.
Undoubtedly, we (adults with CF) should exercise regularly, and parents and clinicians should do what they can to encourage children with CF to introduce this healthy habit as soon as possible. But just as in the case of CFTR-able people, it is no easy task to convince those with lung disease to comply with an exercise prescription. The first obstacle is one of motivation, and the second is the very real issue of time-management. Neither of these are simple problems with simple resolutions; indeed, possible solutions change with the age of the patient and with the severity of the illness. Additionally, the recommendations for mode of exercise are slightly amended as a patient ages.3
The good news about young children is there is never an easier time to get them to move. Furthermore, a caregiver’s power to promote long lasting behaviors at this stage is enormous. Children are wired to be active in short bursts; they play “anaerobically.” They love to sprint or climb or do explosive movements, and then walk around to recover. This is a perfect for children with cystic fibrosis, because research has shown that this type of exercise trains both the anaerobic and aerobic energy systems. This type of play can also be performed for longer periods of time, due to the frequent rest periods. This is significant because the most recent research in exercise physiology shows that it seems to be total volume of daily activity that has the strongest effect on maintaining lung function. In other words, the more daily physical activity that a child is involved in, the slower their lung function will decline. Encourage anything that your child thinks is fun, and if possible, expose them to as many forms of exercise and sport as you can. This not only keeps it interesting for them, it also is beneficial to train their growing bodies in multiple ways. Some favorites are swimming, soccer, basketball, biking, jumping rope, rollerblading, games like tag or capture the flag, jumping on a pogo stick (one of my favorites), or a rebounder (mini-trampoline). The critical thing is consistent daily participation. The recommendation for children with CF is no different from that for healthy children, at least 60 minutes accrued throughout the day. At this age, it is also important that the intensity of the exercise be relatively high, as in a sport such as soccer, where there are frequent bursts of intense running, followed by longer periods of a walking recovery.
Motivation is usually not an issue with this age group, but if it is, delaying favored activities (screen time, reading, shopping) until after playtime works wonders. Some children are extremely motivated by team sports and group activities, while others shy away from them. If a child falls into the latter group, a pedometer may do the trick, or giving them exercise “points” or stickers and offering a great prize for accumulating a target number. It is also very helpful (and healthy for everyone) to establish family rituals that involve exercise. Weekend family hikes or bike rides are not just good for the children, they also establish exercise and time together as family values.
In both girls and boys, aerobic capacity begins to plateau during adolescence. For this reason, it is important to train the aerobic energy system during this stage of development. Aerobic exercise works the lungs, heart, and muscles, thus having a very powerful effect on the oxygen delivery systems in the body. Historically, girls have been at a greater risk for a sudden drop in FEV1 during adolescence, so while exercise is important for both sexes, this is a critical period for girls in terms of health maintenance. Unfortunately, it is also during adolescence that a significant difference in activity level develops between children with CF and healthy children, and this difference is even more marked in girls than boys. Low-level aerobic exercise, such as walking, biking, or leisurely swimming, can be extremely beneficial for building aerobic capacity. In addition, this type of exercise can increase mucus clearance by up to 30%. This type of aerobic activity can be increased substantially by simply having teens walk or ride bikes to school, or to a friend’s house or other planned activity. Fitting as much simple, low-level activity into daily life as possible can slow lung function decline. This is both time-efficient and can be a motivating fact to share with a teenager.
Exercising at a higher intensity is also beneficial, and can be much more tolerable and even enjoyable if done with interval training. This is characterized by two to three minutes of exercise at a moderate intensity, such as jogging quickly or swimming a few laps, followed by a short period of rest for the heart rate and breathing to return back towards baseline, and then repeating this for several intervals. This has the benefit of shortening the exercise session, a very important factor for busy teenagers.
Anaerobic training is also beneficial for adolescents. In sports like soccer or basketball, there are periods of intense exercise (anaerobic) followed by lower level recovery periods (aerobic), so both energy systems are being stressed and therefore, trained. Interestingly, adherence to this form of exercise has been shown to be very high, so kids actually enjoy this type of activity.
Finally, I would be remiss not to mention the myriad benefits of strength training for young men and women with CF. A study recently completed at the Hospital for Sick Children in Toronto shows that upper body strength and anaerobic capacity are significantly related to FEV1.3 Increased muscle mass, which results from weight training, leads to positive health benefits, both physical and psychological. Just as in anaerobic-based sports described above, when lifting weights, the anaerobic system is tasked during the lifting set, and the aerobic system is pushed during the rest phase between sets. On a personal note, it was when I discovered strength training as a young college student that my lifelong “addiction” to exercise took root. Understanding that this was one area where I felt control over my body, where my cystic fibrosis could not hold me back, was by far the strongest motivator to exercise I have ever felt. And I am female, lacking the benefit of testosterone! Imagine how significant it could be for a young man, perhaps smaller than his peers, to discover an activity that he could do to reliably increase strength and muscle mass. As I’m sure we all painfully remember, self-esteem is at its most vulnerable state during adolescence, and when you have a chronic illness, this is magnified. Depression and increased stress are definitely issues to contend with as teens with CF navigate increased time pressures, possible delayed puberty, and increasing health challenges. Exercise is known to increase self-esteem in children with cystic fibrosis, and is also a very effective way to deal with depression and stress.
Just as with younger children, variety improves the interest level and the overall benefits of an exercise program. If a teenager is inclined toward team or individual sports, this is ideal. If not, encouraging as much low-level activity in daily life, introducing interval training, and encouraging resistance training is my recommendation. Whatever the choice of activity, adolescence is the time to emphasize the importance of habitual, daily exercise as a central component to the routine management of their cystic fibrosis. Hopefully, as they notice that they feel and look better when they exercise, your teenager will develop the internal motivation to continue this habit into adulthood.
The most exciting piece of information I’ve seen in researching this topic comes from Toronto, where new interesting and not yet published research that shows that in a seven year follow-up, FEV1, lung function, and habitual physical activity are closely related, and the people with the highest levels of physical activity have a 50 percent slower rate of decline of lung function (emphasis mine).3 For adults with CF, this means one thing: move more! Incorporating physical activity into your daily routine should be as important as your other therapies. Walk as much as you can. Ride a bike. Swim. All of these activities have well-documented positive effects, both CF-specific and non-CF specific. For example, regular exercise both helps with airway clearance and has been shown to be as effective as medication in treating depression and anxiety. For women especially, weight bearing exercise such as walking, jogging, or weight lifting can help stave off osteoporosis. In non-CF subjects, weight lifting improves insulin sensitivity. It isn’t known if this is true in CF, but it certainly could be. Most importantly, regular exercise improves the quality of life and perception of well being, and what can be more important as an adult with CF?
For adults with CF, the exercise recommendation is for “concurrent exercise,” which is medical-speak for cross training. This means it is best to incorporate many different forms of exercise throughout your week. Strength train at least twice a week, work aerobically, at both low and moderate intensity as tolerated, at least three or four days a week, and try to incorporate flexibility and mobility work into your routine on several days. I recommend that people aim for 30 minutes per exercise session, but then also incorporate more movement throughout the day. Obviously, if you have more severe lung disease, you should consult with your doctor as to the need for O2 supplementation or any contraindications to exercise.
There are three important exercise considerations that apply to all age groups. First, if you are sick, don’t workout. While it may seem macho to do so, and healthy people can get away with it, exercise would be an added stressor to an already-taxed system. If you can, continue with low-level activity such as walking, so that you don’t decondition quite as much, and then begin again when you are healthy. Secondly, make sure that with increased physical activity, you or your child with CF are also taking in enough good quality calories to maintain the appropriate body-mass index. Even though exercise correlates strongly with lung function, so does nutritional status, and it would be counterproductive to sacrifice an optimal BMI in your pursuit of fitness. Finally, with increased exercise comes the need for fluid and electrolyte replacement. Especially when exercising in heat or for a long duration, this cannot be overstressed.
Clearly, I am a big fan of exercise. I firmly believe that one of the reasons I have enjoyed such good health as a DDf508 is that I made it a daily habit over 35 years ago. But now, it is not just me and other adults with CF who have seen exercise change their lives, preaching about the need for everyone with CF to add this to their treatment regimen. Research is proving us right, and even giving clues into the mechanisms of the benefits of exercise. As a fifteen-year-old, I didn’t know that my jogging was causing my ENAC channels to be down regulated, thereby increasing airway surface liquid. All I knew was that it made me feel great! I became hooked, and I’m still here, writing about it.
 Nixon, et al, N Engl J Med 1992; 327: 1785-8.
2 Schneiderman-Walker, J Pediatr 2000, 136: 304-10.
3 eCystic Fibrosis Review, March 2012: Vol 3, Number 8.