Variability in Intensity Related to Increased Overall Bout Intensity.

OBJECTIVE: We examined the relationship between variability in self-regulated exercise intensity and overall intensity during acute exercise.

METHODS: Overall, 32 participants (age; 20±4y, body mass index (BMI) 24.1±3.6 kg/m2) completed a 30-minute self-regulated treadmill exercise bout. Participants were blinded to treadmill settings and adjusted speed and incline every 5-minutes as desired.

RESULTS: Variability in exercise intensity (metabolic equivalent standard deviation (METSD)) was positively correlated with (r = .567, p = .001) and explained a significant portion of the overall exercise intensity (ß = .574, t = 3.713, p = .001). When accounting for physiological variables, METSD (ß = .381, t = 2.242, p = .034) and VO2peak (ß = .575, t = 2.864, p = .008) predicted overall intensity. When controlling for physiological and psychological variables, in addition to METSD (ß = .388), tolerance for exercise intensity (ß = 3.124) became a significant predictor of overall bout intensity (p < .05).

CONCLUSIONS: In-task variability in exercise intensity was posi- tively related to the average intensity of the bout. Future studies should explore the utility of explicitly encouraging individuals to incorporate intra-bout variety for increasing the exercise dose while maintaining a degree of autonomy.