Understanding Active Behaviors Among Insufficiently Active Adults During Experimental Studies

Abstract

A recent study examined the impact of TV viewing during exercise on observable volitional behavior (i.e. treadmill endurance time) among insufficiently active adults (46±15 years, 31±5 kg/m2 ; 68% women). Participants completed two visits in a randomized order, with >48H separating them. Participants could sit or walk on the treadmill (moderate intensity) as desired within a 60-minute time frame. During one visit, participants were able to view TV during exercise and while sitting. During the other, TV viewing was allowed only when seated. Despite the average participant accumulating 63±58 minutes of moderate-to- vigorous physical activity (MVPA) per week, 24% of participants walked continuously for 60-min at both visits. PURPOSE: Determine differences in relevant physical, psychological, and behavioral characteristics between participants who walked 60-min in both conditions (WALK, n=6) compared to those who did not (WALK/SIT, n=19). METHODS: T-tests were used to compare physiological (BMI, %body fat, estimated VO2max), psychological (preference for and tolerance of exercise, intrinsic and extrinsic motivation), and behavioral (MVPA/week) factors. RESULTS: Tolerance for exercise intensity was significantly higher in WALK relative to WALK/SIT (3.2 vs. 2.5 p=0.04). No other significant differences were observed >0.05) between WALK and WALK/SIT, respectively (BMI=29.8 m/kg 2 vs. 31.6 m/kg 2, %body fat=34.0% vs. 36.0%, estimated VO 2max =29.4ml/kg/min to 26.6ml/kg/min, intrinsic motivation=2.1 vs. 2.0, extrinsic motivation=1.04 vs.1.07, preference for exercise intensity= 2.6 vs. 2.6. Although not significantly different, WALK reported nearly twice the average minutes of MPVA (83.3 vs. 48.9 min/week, p=0.20). Anecdotally, several participants indicated that, because it was already scheduled, they used this time to exercise regardless of condition. CONCLUSION: The ceiling effect in volitional walking time noted for 24% of participants warrants further investigation. Preliminary descriptive analyses suggest that tolerance of exercise intensity may play a role, while anecdotal data indicate additional motivational factors (i.e. “making use” of experimental visits) should be accounted for. Future studies may consider implementing experimental time frames greater than 60 minutes.