The Effects on Pulmonary Function and Performance from Training Respiratory Muscles in Collegiate Cross Country Runners with PowerLung
M.M. Barnes, D.M. McGee, A.K. Butler and R. Galbreath, Dept. of Physical Therapy, Wheeling Jesuit University, Dept. of Exercise Physiology, Ohio University Eastern, Dept. of A.R. Physiology, Ohio Valley C & R Surgery

Introduction

The purpose of this study was to evaluate if the practice of exercising respiratory and extra-respiratory muscle would make a significant change in both VO2max and performance in collegiate cross-country runners. The respiratory muscles were exercised by utilizing a device called a PowerLung. This device has the ability to create both inspiratory and expiratory resistance. Typically respiratory and extra-respiratory muscles are only taxed in runners during speed training or periods of maximum effort. The goal of this experiment was to determine whether positive benefits could be achieved by maintaining this level of respiratory stress with the PowerLung device at predetermined intervals for a five week period. We hypothesized that with efficacious training of the respiratory muscles, they would strengthen, and this increase would be measurable on a spirometry test. We also hypothesized that this increased strength would lead to improved measures on the treadmill test, specifically in regards to VO2max , lactate threshold (LT), and overall treadmill test time. We anticipated that if positive effects were observed they would be accompanied by a decrease in rate of perceived exertion by the athlete.


 

Review and Theory
It has been documented that like many other muscles in the body, respiratory muscles fatigue with exercise. Respiratory muscle fatigue has been found in many groups, including triathletes and long distance runners. Muscles typically considered involved in respiration are the diaphragm, the abdominal muscles, the intercostals, anterior scalenes, and serratus anterior. Fatigue of specific respiratory muscles has been observed by a number of groups.
It has been shown that the diaphragm fatigues in as little as 10 minutes of exercise. Although extra-diaphragmatic muscles are able to compensate, they too fatigue after time, leading to decreased performance.

 

Inspiration
Muscles of Respiration
Expiration
Accessory Quiet Breathing
Stemocleidomastoid - This accessory muscles of inpsiration elevates the sternum. Expiration results from passive recoil of lungs and rib cage.
Middle Scalene, Anterior Scalene and Posterior Scalene - These accessories muscles of inpsiration elevate and fix the upper rips. REVIEW_MUSCLES_QUIET_2
Principal Active Breathing
External Intercostal Muscles - These principal muscles of inspiration elevat the ribs, thus increasing the width of the thoracic cavity. Internal Intercostals (except interchondral part) - These muscles of active expiration lower the ribs, thus decreasing the width of the thoracic activity.
Interchondral part of Internal Intercostals - This part acts as a principal muscle of inspiration by elevating the ribs. Rectus Abdominis, External Oblique, Internal Oblique and Transversus Adbominis - These muscles of active expriation depress the lower ribs and compress abdominal contents, thus pushing up the diaphragm.
Diaphragm - The domes of this principal muscle of inspriation descend, thus increasing the longitudinal dimension of the thoracic cavity. The diaphragm also helps in elevating the lower rubs.

In the same way that other muscles in the body are able to be trained to limit fatigue and increase performance, the respiratory muscles can also be strengthened. Hyperpnea training has shown to increase strength and performance for patients with Chronic Obstructive Pulmonary Disorders (COPD). There are mixed findings when applying the same principle to healthy subjects. Some studies show increased performance only at levels about 90-95% VO2max, while others found increased performance only in the 65-85% range and a few studies demonstrated no increase in performance at any level. These differences in findings are likely the result of experimental design such as differences of the type and length of training, the subject population, and the performance test recorded.

Our study was to examine the effects of training with a Powerlung device on maximal oxygen consumption (VO2max), which is an indicator of overall fitness level, and the resulting effects on performance as measured in total time on a maximal effort treadmill test. We also looked at the effects on pulmonary function as measured by a spirometry test.


 

What is PowerLung?
PowerLung Sport
PowerLung is the only product to use adjustable threshold resistance training to strengthen respiratory muscles involved in both inspiration and expiration. The above figure demonstrated, the unit is hand held. It is equipped with both inspiration and expiration resistance control gauges which can be used either separately or together. The nose clip is utilized to eliminate air loss and hence resistance loss during breathing.

 

Experimental Subjects
Subjects:
Eighteen collegiate cross country runner, ages 18-25, from a Division II cross country program were recruited. Nine subjects (6 male, 3 female) were randomly assigned to a Powerlung experimental group and the Remaining 9 subjects (5 male, 4 female) were assigned to a control group.

 

Methods

PowerLung Training:
Subjects in the experimental group were given a working PowerLung device (Sport model) and instructed to use the PowerLung five days per week for five week, coordinating days off with speed work, or race days. PowerLung training consisted of 5 sets of 25 breaths, once per day. Resistance to inspiration and expiration were increased once per week. The subjects in the control group were given the same instructions, but were given a PowerLung device that looked exactly like the experimental groups, but only allowed for a maximum of 15% resistance compared to the normal PowerLung.

Maximal Treadmill Testing:
A VO2max test was given before and after the PowerLung training period. Subjects performed a self-selected warm-up and were given an additional 5 minutes at 3.5 mph to acclimate to the treadmill. The VO2max protocol consisted of 2-minute stages, with each stage increasing in difficulty by increasing the grade/incline of the treadmill by 2%. Males began the test at 8 mph and 0% grade, while the females began the test at 6 mph and 0% grade. Metabolic data was acquired using a VacuMed Vista 17001 metabolic ca90 rt with TurboFit analyzing software. Values recorded from this test were VO2, Ventilation (VE), LT, tidal volume (VT), and heart rate (HR).

Pulmonary Function Testing:
Each subject was given a pulmonary function test using a Presto Flash spirometer (Tamarac, Inc.) before the VO2max test both pre and post training. The average of 3 trails were taken and recorded for the following values: forced vital capacity (FVC), forced expiratory volume in 1 second and 3 seconds (FEV1 and FEV3, respectively), and maximum forced expiratory flow (FEFmax).


 

Results
Seven subjects fully completed all aspects of the study: 5 experimental (4 male, 1 female). 2 control (both male). Thirteen subjects completed both the training and pulmonary function tests: 6 experimental (4 male, 2 female), 7 control (4 male, 3 female).

Only 5 weeks of training were completed due to spring break.

Pulmonary Function Testing:
The experimental group had improved measures on FVC, FEV1, FEFmax, and FEV3 (p<0.05)

Forced Expiratory Volume In One Second

Forced Vital Capacity Maximal Treadmill Testing:
No significant differences for VO2 max,, VE, VT, or total time. The control group demonstrated an increase in LT, a decrease in HRmax and a decrease in RERmax

 

Conclusion

Training the respiratory muscles with a Powerlung device using the protocol we developed increased the strength of the respiratory muscles, as indicated by improved values in FVC, FEV1, FEFmax, and FEV3. However these increases in respiratory strength did not lead to an increase in VO2max,, LT, or total performance time during the maximal treadmill test.

Clinical Relevance
Pulmonary compromised individuals who have a greater room for improvement when compared to seasoned collegiate athletes would most likely benefit from utilizing the Powerlung protocol we established in these experiments. Positive improvement in pulmonary function which indicates an increase in strength of the respiratory muscles could play an integral role in treatment plans for the elderly as they progress through declining states of health. And possibly have the potential to offset or slow the progression of functional respiratory losses.

Reprinted with permission by David M. McGee, Wheeling Jesuit University