Enjoyment is considered an important factor in the adoption and long-term maintenance of exercise and physical activity (PA) behaviors (Dishman et al., 1985). In a review of the determinants of PA, Trost, et al. (2002) reported that enjoyment of exercise showed a strong positive association with PA. A growing body of literature also suggests assessing core affective responses during exercise (pleasure vs. displeasure), as these responses are also related to continued exercise behavior and can inform appraisals of enjoyment. (Booth et al., 2000; Ekkekakis et al., 2013; Leslie et al., 1999; Williams et al., 2012b). This hypothesis is rooted in Hedonic Motivation Theory (HMT), which states that individuals will engage in activities they find pleasurable and avoid those they find un pleasurable (Higgins, 2006). Specifically, HMT purports that affective responses (e.g. pride, satisfaction, disappointment) to an activity drives future engagement in that activity (Higgins, 2006).
One plausible way of improving affective responses during exercise (and thus increasing perceived enjoyment) is through distraction. According to the Rejeski's (1985) parallel processing conceptualization theory, external and internal sources of information must compete for the individual's attention, since both cannot be processed simultaneously (Rejeski, 1985). When an individual is distracted by external cues, an accompanying change in mood is often linked to dissociation from internal cues (e.g. increased heart rate, fatigue) (Bigliassi et al., 2016; Lind et al., 2009). Thus, when external stimuli (potential distractors) and internal stimuli (e.g., monitoring of HR or breathing) are both present, the external stimuli must be cognitively salient for dissociation to occur (Pennebaker and Lightner, 1980). Recent research into the brain mechanisms occurring while listening to motivational audiovisual stimuli during exercise has illustrated the effect of the external stimuli on both low and high-frequency waves in the pre frontal cortex (Bigliassi et al., 2016). The authors found that in the presence of a motivational stimuli (sport scene from a movie) the electrical activity in the brain adjusted to decrease the sensation of fatigue in the working muscles. This alteration did not occur in the absence of the motivational stimuli. Thus, in order to improve exercise behavior, it is likely that the addition of distracting stimuli may be beneficial.
A strong body of literature indicates that music promotes dissociation from the internal cues of exercise, resulting in a more positive exercise experience (Karageorghis and Jones, 2014). Two comprehensive reviews (Karageorghis and Priest, 2012a; 2012b) have concluded that listening to music can increase enjoyment of exercise. The evidence shows evidence that both tempo and volume (Edworthy and Waring, 2006; Wilsont and Herbstein, 2003) can impact psychological and physiological responses to exercise to improve enjoyment. More recently, Hutchinson, Karageorghis and Jones (2014) found that exercising to both music-and-video elicited the highest levels of dissociation, lowest RPE, and most positive affective responses regardless of exercise intensity when compared to a music-only group and no music control group. Given this finding, it is reasonable to speculate that watching television during exercise, which combines visual and auditory stimuli, may have a similar impact on psycho-physiological responses to acute exercise.
The rationale for assessing the impact of TV watching on exercise responses is multifaceted. First, television viewing is rated as a highly enjoyable leisure-time activity (Epstein et al., 1995) Whereas previous studies have attempted to reduce screen time to be replaced with PA (Ramsey Buchanan et al., 2016) or use it as a reward for engaging in PA (Vaughn et al., 2013) neither approach would necessarily improve enjoyment of exercise itself. Second, combining the two behaviors may present the opportunity to remove a major barrier to PA (i.e. lack of time), considering that the average US adult watches approximately 20 hours of TV per week (U.S. Department of Labor and Bureau of Labor Statistics, 2013), Third, the results from two studies lend initial support for this approach, warranting the collection of additional empirical data (Overstreet et al., 2016; Privitera et al., 2014). Privitera, et al. (2014) reported that college students who exercised while viewing a pleasurable TV program had a significant increase in pleasant mood, compared to those who exercised while viewing an unpleasurable program or no TV program. However, the study has limitations. Mainly, that despite referring to their primary outcome as "mood" the authors actually assessed "affect" by using what is referred to as the Affect Grid (Russel et al., 1989) and these are distinct concepts. Additionally, the measurements were taken outside the time boundaries (pre and post) of the 10-minute exercise bout. Thus, these measurements might more accurately reflect the "rebound effect" (Bixby et al., 2001) indicating the scores are more representative of a positive experience post exercise and not during it. Overstreet et al. (2016) found that exercise was rated as more enjoyable when watching a nature documentary compared to a no-TV condition. In order to increase the applicability of these findings to a wider range of people and more varied program-type, it is important to determine whether this effect persists when allowing individuals to choose a program to watch (as they have the option to do in free-living situations). Recent research suggests that the content of the distraction impacts mood scores during exercise (Russell et al., 2003) (Privitera et al., 2014). If people watch a preferred TV program, it serves as an enjoyable distraction that could increase enjoyment of exercise and positive affect (Privitera et al., 2014).
Thus, the purpose of the current study was to examine the effects of TV viewing on both psychological (enjoyment, affect) and physiological (heart rate) variables. Adults (age 30-60) enrolled in the study completed three 30-minute bouts of moderate-intensity treadmill walking on separate days. Each session was randomly assigned one of three conditions: 1) watching a favorite 30-minute scripted television program of their choosing, 2) watching a 30-minute section of a nature documentary chosen by the investigators, and 3), a control condition, with no TV or external stimuli allowed during exercise.
Twenty-eight individuals participated in the study. Individuals were recruited by word of mouth, flyers placed on community bulletin boards, and email. The inclusion criteria were as follows: 30 to 60 years of age, body mass index between 18.5-44.0 kg x [m.sup.-2], accumulating insufficient levels of PA (less than 150 minutes per week of moderate intensity PA and/or 75 minutes of vigorous PA) (Centers for Disease Control and Prevention (CDC), 2001) and able to perform 30 minutes of continuous moderate intensity exercise on a treadmill. Individuals who had contraindications to exercise, determined by administering a physical activity readiness questionnaire (PAR-Q) (Thomas et al., 1992), or an injury/physical limitation that rendered them unable to meet this requirement, were excluded. Potential participants were also asked to list their three favorite half-hour TV programs. If none of the programs were available (via Amazon Prime or Netflix.com) the participant was excluded from the study.
The participants attended four laboratory visits led by the same researcher. Informed consent was obtained in accordance with a study protocol approved by the university's institutional review board (IRB). Subsequently, individuals were enrolled in the study and were randomly assigned to perform condition one, two, or three for the first trial. During the first visit, height was measured to the nearest millimeter using a standard Seca stadiometer (Birmingham, United Kingdom), and weight was measured to the nearest 0.05 kilogram (kg) with a calibrated Health-o-meter digital scale (Boca Raton, Florida) (Table 1). Resting heart rate (HR) and blood pressure (BP) were measured after the participant had been seated at rest for five minutes. Participants completed a series of questionnaires designed to assess basic demographic characteristics and TV viewing habits.
Participants were instructed to arrive at the initial lab visit having not consumed any caffeine...