Change in the of breathing is accomplished by altering the amount of time spent in both inspiration and expiration, whereas altering the of breathing is accomplished through stimulation of accessory muscles, which results in greater thoracic volume changes.

Rate and depth.

Explanation:

Breathing may be defined as the process of intake of oxygen and exhalation of carbon dioxide. The inhalation and exhalation depends on the partial pressure of gases, atmosphere and pressure of alveoli.

The breathing rate can be changed easily by increasing or decreasing the time of inspiration and the expiration. This changes the volume of oxygen and carbon dioxide in the body. The depth of breathing is controlled by the respiratory center present in the brain. The stimulation of the accessory muscles may increase the thoracic volume change and alters the breathing depth.

Thus, the answer is rate and depth.  

it also supports my hypothesis. if you rest first you can squeeze the clothespin more times. from the data i collected the average of the eight people concluded exercise makes your muscles more fatigued and less able to squeeze the clothespin compared to resting before squeezing.