Loading Aspect        
Number of breaths for which load is applied One1 Two2-5 Five6  
Number of different loads used and how often applied 8loads applied over three trials3 5 loads applied twenty five times in a single trial1,2 9 loads applied four times1 Two trials of 9 loads applied three times1
Number of interspersed unloaded breaths 4-203 3-61,6 5-104  
1Davenport PW and Kifle Y [5], 2McQuiad et al. [2], 3Wiley and Zachman[10], 4Puddy et al.[13], 5Bennet et al. [18], 6Fritz et al. [4].
Table 2: Different loading protocols reported in the literature.