Improving Lung Function Through Strength Training

The diaphragm is an essential skeletal muscle that is chronically active and is among the most aerobically adapted muscles (Ottenheijm et al., 2008). During inspiration, the diaphragm and external intercostal muscles contract, causing the rib cage to expand, moving the thoracic cavity outward and increasing lung volume. During exhalation, the diaphragm and intercostals relax, causing the thorax and lungs to recoil. 

Patients with COPD have greater diaphragmatic recruitment than healthy subjects during resting breathing. One theory is due to hyperinflation-induced diaphragm shortening. Along with increased fiber recruitment, there is a reduced cross-sectional area of Type I and II fibers. 

It has been reported that the diaphragm of patients with COPD has a higher proportion of fatigue-resistant Type I fibers, a lower proportion of fatigue-resistant Type IIa fibers, and very few fatigue-sensitive Type IIx fibers (Kim et al., 2008). Furthermore, Orozco-Levi and colleagues (2001) reported that FEV1 was inversely correlated with sarcomere disruption density (2–45 abnormal areas/100 m2) and area fraction (1.3–17.3%).

What does this mean?

Adaptive changes in respiratory neuromuscular facilitation in chronic lung diseases change the contractile force production, leading to increased abdominal muscle strength and decreased diaphragmatic strength (Pinet et al., 2003). 

How to improve diaphragm efficiency? 

Increased muscle tensile strength can improve mechanical muscle function and heighten motor unit recruitment, frequency, and excitability (Gransee et al., 2012). The respiratory muscles have similar characteristics to peripheral muscles, 

Resistance training improves Type I and Type II skeletal tissue. This is why inspiratory muscle training is commonly used to improve diaphragmatic strength and endurance. However, it is essential to understand that inspiratory muscle training is not the ONLY resistance training approach to improve respiration. 

Multi-joint strength training increases adaptive changes in skeletal muscle that can improve posture and bone density, leading to improvements in stresses applied to the body during everyday movements.

These adaptive changes increase movement efficiency leading to decreases in resting heart rate and reducing the work needed by the diaphragm to get oxygen to the muscles. When the body is strong, the capacity to move is high, leading to respiratory demand.  

Remember, the diaphragm has similar skeletal tissue characteristics to peripheral muscles (arms & legs). Therefore, improving overall strength will help improve the role of the diaphragm within respiration and help enhance lung function.

High Intensity Interval Training: Thinking Beyond Speed

Training in short bouts with limited recovery between exercises has shown to produce positive net gains to improvement in overall exercise capacity. The harder you work and the less recovery you have between sets, creates a formula that will push the limits of the cardiorespiratory system to a point where performance will decline. There has been a collective approach in the variations of programming styles used to properly program interval training. One programming approach we use at PPI is pairing a lower body conditioning based exercise with a tempo based upper body strength exercise. For example, completing kettlebell swings for 15 repetitions and then performing 5 tempo push-ups (3 down, 1 hold, 2 up). There a few reasons why we design our programs in such a way:

Reason 1

            Right off the bat, you are pairing upper body and lower body exercises together. As a result, by the end of your workout you will have been able to get in a full body workout. Something that can be often hindered during the week due to unforeseen barriers in our lives (e.g., work and/or family needs). Getting in more than 3 workouts in a week can be challenging, weather can play a factor, or the biggest barrier of all, having enough time always plays a role in the ability to complete an exercise. Pairing upper and lower body exercises can help reduce that.

Reason 2

            The outcome will always be the same in interval based training. You will fatigue and your body can’t keep up with the demand that is required. When this happens, exercise form is comprised and quality exercise movement declines quickly. No one can keep perfect form while exhausted, just trying to catch their breath between intervals. Even the best conditioned athletes will eventually fatigue and falter. Integrating slow controlled movements like tempo push-ups doesn’t allow you to dial up the intensity on that exercise, so you don’t have a choice but to go slower. This makes you focus on control of the movement and trying to get the brain and body to learn how to regulate under fatigue by slowing down on the exercise. It also helps reduce poor movement mechanics, which can be an accelerator of poor movement mechanics when fatigue is higher.

Reason 3

            The last reason comes from anecdotal evidence. Pairing a push-up with a swing doesn’t allow the musculature around the ribcage to maximize its role in inspiration. This is because the chest and shoulder muscles are working through the reps. The pectoralis muscle helps with inspiration and following an exercise such as kettlebell swings, it’ll be working to recover. However, when you go to perform a push-up, it changes the percentage at which its utilized as an inspiratory muscle and shifts over to the prime mover role causing reduced focus on maximizing chest wall expansion required for breathing.    

            Now there are many factors you can introduce into this discussion to consider optimal programming for interval training. Context is a very important factor and the environment plays a major role in how training is programmed and implemented. Pairing two exercises together as a unit that target the whole body and then changing the rate of speed, can be a beneficial approach to maximizing exercise output while reducing the risks in decreasing the quality of work. Higher intensity interval training can be done in a way where speed and power do not always take center stage. Less reps with more time under tension is a viable pairing within an interval based workout to repeat the positive benefits of from many elements that push physical output to the limits.