Regular physical activity is strongly associated with decreasing the risk of disease and improving the quality of life (13,15). Specifically, regular physical activity can reduce the risk of cardiovascular disease, type II diabetes, and obesity (16). Unfortunately, a high percentage of US adults are not active enough to receive these health outcomes (3,4). Consequently, lack of physical activity has become the second leading cause of preventable death (14). An approach that may increase physical activity is to use the services of a personal trainer.
Personal trainers provide many benefits to individuals through one-on-one sessions. The benefits of exercising with a personal trainer may include exercise support, guidance, and reinforcing feedback (14). Furthermore, research has shown that exercise attendance significantly increases when using a personal trainer (12). Despite many benefits of exercising with a personal trainer, there are also many barriers such as lack of facilities, enjoyable activities, funds, and time (7,15).
An alternative to using personal trainers in a health club may be video-guided exercise (e.g., digital video disk [DVD]) at home. The popularity of video-guided exercise has grown, as evidenced by exercise DVD sales increasing from $155.4 million in 2007 to $264.5 million in 2012 with an average growth of 11.2% per year (9–11). Benefits of using exercise DVDs may include lower cost, convenience of time, and feasible exercise location (15). Home-based DVD exercising can also allow the exerciser to select their training intensity. This may prove to be beneficial because overweight adults are more likely to adhere to exercise when it is self-selected and unsupervised compared with supervised and prescribed exercise (14).
Ekkekakis and Lind (6) found that overweight women worked at a relative higher oxygen uptake during both self-selected and imposed intensity exercise than normal weight women. Although the ratings of pleasure did not differ for either group in the self-selected session, the overweight women reported a significant decline in the imposed session (6). Self-selected exercise can be similar to exercising with a DVD in that individuals select the intensity in which they will exercise throughout the session. Perri et al. (14) reported overweight adults are more likely to adhere to exercise when it is self-selected and unsupervised compared with supervised and prescribed exercise. Although the effect a personal trainer has on exercise behavior change has been studied (8), there is a lack of research regarding the effectiveness of a personal trainer during an exercise session with low-to-moderately fit females.
Fischer and Bryant (8) reported that personal trainers had a significant positive effect on exercise behavior change on college students. The experimental group in this study maintained the same number of students exercising at the set criteria, whereas the control group, that did not receive personal training services, experienced decline from the set exercising criteria. Despite the growth of the exercise market and the known benefits of being physically active, the effectiveness of live vs. DVD-guided training on exercise intensity and energy expenditure is still unknown. Therefore, the purpose of this study was to determine the effects of DVD exercise vs. live training on exercise intensity and energy expenditure in low-to-moderate fit females. We hypothesized that the DVD lead session would elicit higher exercise intensities and greater energy expenditures than the live exercise session.
Experimental Approach to the Problem
Currently, the use of personal trainers and DVDs are popular tools for promoting exercise. There is a lack of research that compares the physiological effects in both DVD and live exercise sessions. To evaluate the effectiveness of DVD exercise vs. a personal trainer through exercise intensity and energy expenditure, participants completed 2 vigorously intense circuit style workouts. The warm-ups for both the DVD and live sessions consisted of a 5-minute dynamic warm-up using 6 exercises performed at a low-to-moderate intensity. After the warm-up, individuals completed the same 6 exercises at a higher intensity. The order of exercise sessions was randomly counterbalanced for each participant. All subjects completed identical workouts, 1 with a personal trainer and 1 with a DVD. Metabolic data were collected through an Oxycon Mobile (CareFusion, Hoechberg, Germany), a portable metabolic system, with heart rate being assessed through a Polar monitor (T31 Transmitter; Polar Electro, Kempele, Finland).
Twenty active and low-to-moderate fit female volunteers (age ranges of 18–27 years) participated in this live vs. DVD-guided exercise study (Table 1). This study was approved by the university institutional review board before data collection. All participants read and signed a written informed consent approved by the university institutional review board before data collection. Each participant completed initial screening visits, a live exercise session with a personal trainer, and a prerecorded exercise session with the same personal trainer within 2 weeks. Participants were familiarized with all procedures and equipment used in this exercise study before all testing and exercise sessions. All participants were instructed to avoid caffeine, be well hydrated, get plenty of sleep, and to avoid any drastic changes in nutrition. Exercise sessions were completed around the same time of day.
To qualify for this study, participants had to be in a low-to-moderate risk according to American College of Sports Medicine's (ACSM's) risk stratification (1). The following risk factors were accessed by questionnaire: family history, cigarette smoking, dyslipidemia, sedentary lifestyle, fasting glucose, and high-density lipoprotein cholesterol (HDL) values. A resting blood pressure (Adcuff; American Diagnostic Corporation, Hauppauge, NY, USA) was measured in the initial visit to assess hypertension. Body mass index (BMI) was also calculated after height and weight measurement in the initial visit to determine risk stratification. A calibrated beam scale and stadiometer (Model 222; SECA Corporation, Hamburg, Germany) were used to record height (in centimeters) and body mass (in kilograms). Blood glucose was analyzed to determine whether individuals received an additional risk factor of prediabetes when BMI was 25 kg·m−2 or greater (1). After completion of the initial screening, participants were asked to report to the laboratory fasted (no food or drink beside water for 10 hours) to complete a blood draw. However, individuals who had normal BMI measures and no other risk factors were considered low risk and did not participate in the blood draw.
Skinfold measurements (Lange, Cambridge, MD, USA) were taken at 7 sites (subscapular, triceps, chest, abdominal, thigh, suprailiac, and midaxillary) and used to estimate percent body fat using ACSM's Guidelines for Exercise Testing and Prescription eighth edition population-specific formulas (1). Participants were asked to refrain from eating and drinking, other than water, 2 hours before the exercise session. After anthropometric measurements (i.e., height and weight) were collected, participants completed a single-stage treadmill test. The single-stage treadmill (Fitnex, Dallas, TX, USA) test was used to estimate participant cardiorespiratory endurance fitness level (5). Each participant was also stratified according to ACSM guidelines for risk of cardiovascular injury during exercise. Intrinsic and extrinsic motivational questionnaires as well as a depression questionnaire were also completed at this time.
Participants reported to the laboratory on 2 separate occasions to perform the same circuit style workout. Each participant properly demonstrated each of the exercises during the preparticipation assessment. Before each exercise visit, participants were asked to refrain from eating or drinking, other than water, 2 hours before the session. The exercise sessions began with a 5-minute dynamic warm-up that consisted of 6 exercises (i.e., mock rope jumping, jumping jacks, high knees, airborne Heisman's, oblique twist, and swing kicks) completed at a low intensity for 45 seconds each. After the warm-up, participants performed the same exercises twice at a higher intensity for 1 minute separated by a 45-second rest period. The workout portion of the session lasted approximately 20 minutes. One session was completed with a live personal trainer. The other was completed with a prerecorded DVD of the same personal trainer and identical exercises. In the DVD session, participants exercised in an enclosed room where participants could not be watched during the exercise session. A researcher sat outside of the enclosed room during the DVD session for safety purposes.
During each exercise session, metabolic data (e.g.,
and respiratory exchange ratio [RER]) were measured using an Oxycon Mobile (CareFusion). The Oxycon Mobile is a portable metabolic measurement system that can measure expired amounts of oxygen and carbon dioxide as well as ventilation. The Oxycon system collected data in a breath by breath manner. Before each use, the system was calibrated using a gas of known concentration (4.01% CO2, 15.98% O2).
Heart Rate and Rate of Perceived Exertion
Heart rate response was assessed using a Polar monitor (T31 Transmitter, Polar Electro). Borg 6–20 rate of perceived exertion (RPE) scale was assessed after each exercise bout and following the whole session (2). Participants were blinded to heart rate response throughout the session. After both exercise sessions, participants completed a “Post Exercise Psychological Questionnaire” (PEPQ) that measured various psychological factors (i.e., comfort, confidence, enjoyment, stress, and anxiety) on a 5-point Likert scale ranging from strongly disagree to strongly agree (Table 2).
Mean values and SDs for descriptive characteristics of participants were calculated. Repeated measures analyses of covariance (ANCOVAs) were used to determine whether intrinsic motivation or extrinsic motivation scales were covariates in a model comparing the heart rates and energy expenditures of the DVD and live exercise sessions. Both energy expenditure and average heart rate for the entire live and DVD sessions, including rest periods, were compared using a within-persons 1-way repeated measure ANOVA. Exercise energy expenditures, not including the rest periods, between the live training and video-guided sessions were compared for each exercise interval using paired t-test. Rest periods between each exercise were compared between live training and video-guided exercise using paired t-test. A paired sample t-test was also used on recorded heart rates between the live and DVD-guided individual exercises (e.g., mock jump rope). Mean values and SDs for intrinsic and extrinsic motivation questionnaires were calculated. The Wilcoxon signed-rank test was performed to compare the PEPQ questions between the exercise sessions (Table 2). Finally, frequencies were used on a question focused on which exercise session (DVD or live) was preferred. The alpha level for the study was set at p ≤ 0.05.
Descriptive data for subjects are presented in Table 1. Neither intrinsic (3.3 ± 0.3) nor extrinsic (3.3 ± 0.4) motivation was a significant covariate of heart rates or energy expenditures when comparing exercise sessions (DVD vs. live). Energy expenditure (F(1,19) = 23.04, p < 0.001, η2 = 0.56) and heart rate (F(1,19) = 16.88, p = 0.001, η2 = 0.47) were significantly higher for the live session (i.e., 5.94 ± 1.06 kcal·min−1, 154 ± 18 b·min−1) vs. the DVD exercise session (i.e., 5.31 ± 1.12 kcal·min−1, 144 ± 17 b·min−1) (Figures 1A, B). Overall RPE was also significantly higher for the live session (i.e., 14.20 ± 3.49) compared with the DVD session (i.e., 12.87 ± 3.44), (F(1,19) = 4.83, p = 0.045, η2 = 0.26) (Figure 1C). Energy expenditure for high knees, airborne Heisman's, and swing kicks were also significantly greater for the live session vs. the prerecorded session (Figure 2A). Average heart rate was significantly higher for the live exercise session for mock jump rope, high knees, airborne Heisman's, and swing kicks (Figure 2B). The Wilcoxon signed-rank test revealed no significant difference in the PEPQ questions that assessed the participants comfort, confidence, enjoyment, stressfulness, and anxiety, when comparing the personal training session to the DVD session. Intraclass correlations were determined for each component of the PEPQ: comfort (r = 0.60), confidence (r = 0.64), enjoyment (r = 0.87), stressfulness (r = 0.91), and anxiety (r = 0.96). Furthermore, 89% of individuals stated that they preferred the live session over the DVD session.
With the majority of Americans failing to meet the weekly physical activity requirements, determining the most productive setting to elicit higher exercise intensities (i.e., live vs. DVD) would be beneficial. The current study compared DVD led exercise to personal trainer–led exercise among college-aged females. This study was the first of its kind to examine DVD vs. personal training exercising in this population. The outcomes of the current study cannot be explained by participant intrinsic or extrinsic motivation due to the homogeneity of the motivation scores within our sample. Also, anxiety and comfort level were likely similar because the same personal trainer was used in both the live and DVD sessions. The hypothesis of this study was not confirmed because the results indicated a significant (10 b·min−1) increase in heart rate and (0.63 kcal·min−1) energy expenditure for the entire personal trainer session vs. the DVD session (Figures 1A, B).
The results from our study suggest that working with a personal trainer may produce higher caloric expenditure than using DVD-led exercise. Our findings are interesting because Fischer and Bryant (8) found that college students receiving personal training services exercised on 3 or more days of the week, whereas college students who did not receive personal training services regressed. The combination of the findings from our study and the findings of Fischer and Bryant (8) suggest that working with a personal trainer may produce significantly higher weekly energy expenditure. When considering strategies to meet or exceed weekly physical activity standards, these studies suggest that using a live personal trainer is more effective than using DVD-led exercise sessions.
The total exercise intensity differences between exercise sessions were strictly due to exercise intensity differences between 3 exercises (i.e., high knees, airborne Heismann's, and swing kicks) (Figures 2A, B). These 3 exercises involved substantially more hip flexion than the remaining nonsignificant exercises. More than likely, participants lifted their legs higher with a personal trainer present than during the DVD session thereby increasing their energy expenditure and heart rate. A reasonable explanation for the findings could be that the presence of the personal trainer encouraged greater effort from the participant. Heart rate was also significantly higher for mock jump rope in the personal trainer session compared with the DVD session. Despite the warm-up exercises being identical in both sessions and an outlier being removed from the analysis, heart rate continued to show significance. One plausible explanation for the significance is the participants could have been more nervous with the personal trainer present causing an increase in heart rate during the first exercise (i.e., mock jump rope).
Mean values for overall RPE were approximately 2 units higher for the personal trainer session than the DVD session although both sessions were identical in exercises and encouragement from the personal trainer (Figure 1C). Although participants perceived higher exertion in the personal trainer session, 89% of participants preferred the personal trainer session over the DVD session. These findings suggest that personal trainer–led sessions are preferred over DVD-led sessions despite higher exercise intensities. Therefore, personal trainers may be more beneficial than DVDs in promoting energy expenditure and attaining physical activity guidelines. However, future research in facility and home-based setting is needed.
The DVD exercise session is often performed in a home setting and at self-selected intensity. Ekkekakis and Lind (6) found that overweight women work at a higher relative oxygen uptake than normal weight women in both self-selected and imposed intensity exercises. Perri et al. (14) observed that overweight women demonstrated a significantly greater caloric expenditure in a home setting when compared with a group setting. These studies suggest that overweight women will have a higher caloric expenditure in an environment that is free of prescribed intensity. The current study's results do not agree with this reasoning. A possible explanation could be the difference in populations between the current study and the previously described studies. Our study used low-to-moderately fit females and the other studies used overweight females. There is currently a lack of research comparing overweight females in the model used in our study.
With the lack of research in this area, further research is needed using similar models to this study in several populations. The homogeneity of the participants in the motivation and the PEPQ questions is a limitation that could be addressed in future research. The current study also had a homogenous group by having college-aged females of low-to-moderate fitness. Future studies could have a heterogeneous group through various ages or fitness levels of participants to determine whether motivation or anxiety is significant predictors of which exercise session is more effective. A strength of the current research included it being an efficacy study in which the exercise sessions were performed in a well-controlled laboratory setting.
In this study, current results suggest that exercising with personal trainer significantly increases energy expenditure for low-to-moderate fit, college-aged females. The current study provides evidence that using personal trainer–led exercise is more effective at increasing energy expenditure and heart rate than DVD-led exercise. Furthermore, a great majority of participants preferred the personal trainer session over the DVD session. These findings suggest that personal trainers may improve caloric expenditure when compared with DVD-led exercise session and therefore may promote greater weight loss.
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Keywords:Copyright © 2014 by the National Strength & Conditioning Association.
personal trainer; video-guided workout