Date of Award


Document Type

Open Access Thesis

Degree Name

Master of Science (MS)



First Advisor

James Hokanson, Ph.D.

Second Advisor

Joy L. Hendrick, Ph.D.

Third Advisor

Peter M. McGinnis, Ph.D.


Exercise endurance in multiple populations has been shown to increase after bouts of respiratory muscle training (RMT) (Bailey, Romer, Kelly, Wilkerson, Dimenna & Jones, 2010; Brown, Sharpe, Graham & Johnson, 2008; Griffiths & McConnell, 2007; Kilding, Brown & McConnell, 2007; Laoutaris et al., 2012; Markov, Spengler, Stuessi, Boutellier & Knöpfli-Lenzin, 2001; Spengler & Boutellier, 2000; Stuessi, Spengler, Knöpfli-Lenzin, Markov & Boutellier, 2001; Volianitis et al., 2000). The use of resistance via respiratory muscle strength training (RMST) has been shown to produce greater increases in endurance than with no resistance, but the method of RMST that produces the greatest increases in exercise endurance is still unknown (Illi, Held, Frank & Spengler, 2012). The purpose of this study was to determine whether inspiratory muscle training (IN) or inspiratory with expiratory muscle training (INEX) would have the most significant increase on exercise endurance, as measured by a constant-load cycling test at 70% of maximum power output. Subjects were randomly assigned to one of three groups: an inspiratory muscle training group (n=11), an inspiratory with expiratory muscle training group (n=11) and a placebo group (n=7). The non-placebo groups trained five times per week, two times per day, 3-5 hours apart. Their training consisted of forceful breathing through a RMT mask 30 times per training session. The placebo group trained five days per week, once per day, and took 60 regular breaths at tidal volume through the mask. After four weeks of training, the inspiratory with expiratory muscle training group saw an average increase of 75% between pre- and post-exercise endurance tests. The inspiratory muscle training group saw a 28% increase in endurance time and the placebo group saw a 7% increase in endurance time. These were not statistically significant. Inspiratory with expiratory muscle training may produce the greatest increase in exercise endurance, but more research with a variable group of participants in even groups is necessary to confidently make this conclusion. Inspiratory with expiratory muscle training could have a greater benefit than inspiratory muscle training in multiple populations, including individuals with exercise-induced asthma because these individuals experience difficulty exhaling air while working at 80% or greater of their VO2max (Wuestenfeld & Wolfarth, 2013). INEX would train the muscles of expiration, while IN alone would not.