On average, starting an exercise training program decreases one’s risk for chronic disease. However, there is remarkable individual variability in physiologic responses to exercise training. The activity and inactivity during the remaining 95% of the day (when the individual is not training) is rarely considered. The overall objective of this dissertation was to apply validated sedentary behavior (SB) and physical activity (PA) measurement techniques during an exercise training study to determine if time spent in SB and PA outside of training influences the physiological response to training. Twenty subjects participated in a pilot study to determine the feasibility of reducing SB and the validity of PA monitors for measuring SB compared to direct observation (DO). Participants completed a 1-week baseline period and a 1-week intervention period, where they were instructed to decrease SB. The correlation between the AP and DO was R2=0.94 and the AG100 and DO sedentary minutes was R2=0.39. SB significantly decreased from 67% of wear time (baseline period) to 62.7% of wear time (intervention period) according to AP. Only the AP was able to detect reductions in SB and was more precise than the AG. Study Two was a 12-week randomized controlled study. There were 4-groups that were instructed to: 1) CON: maintain habitual PA and SB 2) rST: reduce and break-up SB and increase daily steps 3) EX: exercise 5-days per week for 40-minutes per session at moderate intensity 4) EX-rST: combination of EX and rST. Cardiovascular disease risk factors were assessed pre-and post-intervention. The AP was used to verify AP between-group differences in activity at four time-points. EX-rST had improvements in insulin action variables that EX did not. All other physiologic responses to training were similar between EX groups and rST has less robust changes than either EX group. These data provide validation of activity monitors for measuring SB and present preliminary evidence that activity outside of exercise training may influence the metabolic response to training. This dissertation shows that what is done outside of exercise training can and should be quantified using objective monitors that assess daily exposure to activity and inactivity behavior.