BACKGROUND: As the prevalence of obesity and inactivity continue to increase worldwide, the need for effective intervention strategies remains. Despite the well-known benefits of leading a physically active lifestyle, of those individuals classified as obese, only 3.0% of the women and 6.4% of the men trying to lose weight actually meet the 60 min/day physical activity guidelines for weight management (Bish et al., 2005). With lack of time being one of the most oft-cited reasons for not being active (King et al., 2000), the use of short-duration, high-intensity interval training (HIT) has been suggested as a time-efficient means to potentially address this problem (Gibala, 2007). However, the long-term sustainability of the HIT approach in non-athletic populations has not been investigated. Affective responses to bouts of exercise have been linked to exercise adherence (Williams et al., 2008) and, importantly, obese individuals have been found to report lower levels of pleasure in response to exercise than normal-weight and overweight individuals (Ekkekakis, Lind & Vazou, in press).

PURPOSE: Thus, the aim of the present study was to compare the affective responses of obese women during a shorter, high-intensity interval session and a longer, isocaloric moderate-intensity session, in order to evaluate the appropriateness and practicality of implementing HIT exercise for this population.

METHODS: Twenty-four obese and inactive women (mean age 39.25 years) first completed an incremental cycle ergometer exercise test to determine their ventilatory threshold (VT). They then completed two experimental exercise conditions that were counterbalanced: 1) a high-intensity interval session (HIT) that involved 4 intervals of cycling at 85% of VT for 2 min and 115% of VT for 3 min for a total of 20 min and 2) an isocaloric, moderate-intensity bout (MOD) that involved cycling at 90% of VT for 25 min. The Feeling Scale was administered before, during, and after exercise. The Physical Activity Enjoyment Scale (PACES) was also administered after the cool-down.

RESULTS: The participants' Feeling Scale and PACES scores were significantly lower (indicating less pleasure and enjoyment, respectively) during the HIT session, than the MOD session.

CONCLUSION: On the basis of affective responses and enjoyment, the HIT protocol used in the current study appears to be even more challenging than the traditional MOD format for obese inactive women. These data may have implications for the practicality and long-term sustainability of HIT training protocols in the domain of public health. In evaluating the appropriateness of the HIT approach for inactive obese women, exercise practitioners should take into consideration the impact of this method on affective responses, as well as its possible implications for adherence.