Kara I. Gallagher

Evaluation of the SenseWear Pro Armband to assess energy expenditure during exercise.

PURPOSE To assess the accuracy of the SenseWear Pro Armband for estimating energy expenditure during exercise. METHODS : Forty subjects (age = 23.2 +/- 3.8 yr; body mass index = 23.8 +/- 3.1 kg x m) performed four exercises (walking, cycling, stepping, arm ergometry) with each exercise lasting 20-30 min and workload increasing at 10-min intervals. Subjects wore the SenseWear Pro Armband on the right arm, and energy expenditure was estimated using proprietary equations developed by the manufacturer. Estimated energy expenditure from the SenseWear Pro Armband was compared with energy expenditure determined from indirect open-circuit calorimetry, which served as the criterion measure. RESULTS : When a generalized proprietary algorithm was applied to the data, the SenseWear Pro Armband significantly underestimated total energy expenditure by 14.9 +/- 17.5 kcal (6.9 +/- 8.5%) during walking exercise, 32.4 +/- 18.8 kcal (28.9 +/- 13.5%) during cycle ergometry, 28.2 +/- 20.3 kcal (17.7 +/- 11.8%) during stepping exercise, and overestimated total energy expenditure by 21.7 +/- 8.7 kcal (29.3 +/- 13.8%) during arm ergometer exercise (P < or = 0.001). At the request of the investigators, exercise-specific algorithms were developed by the manufacturer and applied to the data that resulted in nonsignificant differences in total energy expenditure between indirect calorimetry and the SenseWear Pro Armband of 4.6 +/- 18.1 kcal (2.8 +/- 9.4%), 0.3 +/- 11.3 kcal (0.9 +/- 10.7%), 2.5 +/- 18.3 kcal (0.9 +/- 11.9%), and 3.2 +/- 8.1 kcal (3.8 +/- 9.9%) for the walk, cycle ergometer, step, and arm ergometer exercises, respectively. CONCLUSIONS It appears that it is necessary to apply exercise-specific algorithms to the SenseWear Pro Armband to enhance the accuracy of estimating energy expenditure during periods of exercise. When exercise-specific algorithms are used, the SenseWear Pro Armband provides an accurate estimate of energy expenditure when compared to indirect calorimetry during exercise periods examined in this study.

Perceived exertion, electromyography, and blood lactate during acute bouts of resistance exercise.

PURPOSE This study examined ratings of perceived exertion (RPE) during resistance exercise in women. In addition, changes in blood lactic acid and biceps muscle activity assessed using electromyography (EMG) were investigated as potential mediators of RPE during resistance exercise. METHODS Twenty female volunteers (age, 25 +/- 4 yr) performed one set of biceps curl exercise at 30%, 60%, and 90% of their one-repetition maximum (1-RM). Total work was held constant by varying the number of repetitions during each of the three intensities. The three intensities were performed in random order. RPE responses were assessed for both the active muscle (RPE-AM) and the overall body (RPE-O) following each intensity. EMG data were collected from the biceps brachii muscle during each intensity. Blood samples were taken before and following the intensities and analyzed for blood lactic acid concentration. RESULTS A two-factor repeated-measures ANOVA showed a significant RPE (region) x intensity interaction (P < 0.02). Both RPE-AM and RPE-O increased as the intensity of exercise increased. EMG activity increased significantly (P < 0.01) as the intensity of exercise increased. A two-factor repeated measures ANOVA performed on the blood lactate data showed a significant (P < 0.04) time x intensity interaction. Postexercise [Hla] was significantly greater (P < 0.01) at 90% 1-RM than at 30% 1-RM. No significant differences were found in [Hla] between 30% and 60% 1-RM, or between 60% and 90% 1-RM. CONCLUSION These results indicate that monitoring RPE may be a useful technique for regulating resistance exercise intensity. Moreover, blood lactate and activity of the involved muscle may mediate the relation between RPE and resistance exercise intensity.

Ratings of perceived exertion during low- and high-intensity resistance exercise by young adults

Ratings of perceived exertion (RPE) are commonly used to monitor the intensity of aerobic exercise. Whether ratings of perceived exertion can be used similarly during resistance exercise is unclear. To examine this question, perceived exertion was measured at 30% and 90% of the one-repetition maximum (1-RM), while holding work constant between intensities. Ratings for the active muscles and for the overall body were examined during both intensities. 10 male (age = 23.2 ± 3.6 yr.) and nine female (age = 21.8 ± 2.7 yr.) volunteers underwent a one-repetition maximum procedure for each of the following exercises; bench press, leg press, latissimus pull down, triceps press, biceps curl, shoulder press, and calf raise. All subjects then completed two experimental trials on separate days. The high-intensity trial consisted of one set of five repetitions at 90% of the one-repetition maximum. The low-intensity trial consisted of one set of 15 repetitions at 30% of the one-repetition maximum. Active muscle and overall body ratings of perceived exertion were obtained immediately at termination of each of the seven exercises at both intensities. A two-factor (RPE x Intensity) repeated-measures analysis of variance was performed separately for each exercise. Both active muscle and overall body ratings of perceived exertion were higher (p<.01) for the high-intensity trial than for the low intensity trial. Active muscle ratings were higher (p<.01) than overall body ratings for all exercises. Ratings of perceived exertion during resistance exercise are related to intensity of the resistance exercise (percentage of the one-repetition maximum). This information suggests that ratings of perceived exertion can provide information regarding the intensity of resistance exercise. Furthermore, sensations of exertion in the active muscles during resistance exercise are greater than sensations for the overall body.

Self-regulated cycling using the children's OMNI Scale of Perceived Exertion

PURPOSE An estimation and production paradigm was used to determine whether clinically normal 8- to 12-yr-old female (N = 18) and male (N = 18) children could (a) self-regulate intermittent cycle ergometer exercise using a prescribed target rating of perceived exertion (RPE), (b) discriminate between target RPEs, and (c) produce intermittent target RPEs in both an ascending and descending sequence. METHODS Overall body RPE was assessed with the Childrens OMNI Scale (0-10). Subjects underwent (a) one orientation trial, (b) one estimation (E) trial, and (c) two production (P) trials. During E, RPE was estimated each minute of a progressive cycle ergometer test. During the 3-min intermittent P trials, subjects titrated cycle brake force to produce either an RPE sequence of 2 and 6 (ascending) or 6 and 2 (descending). The P trials simulated short, intermittent exercise typical of childrens play. RESULTS Oxygen uptake (VO2) did not differ between E and P at a target RPE of 2 (0.63 versus 0.66 L x min(-1)) and 6 (1.27 vs 1.21 L x min(-1)). Heart rate (HR) did not differ between E and P at a target RPE of 2 (104.1 vs 102.6 beats.min-1) and 6 (153.7 vs 154.5 beats x min(-1)). Both VO2 and HR were higher (P < 0.01) at a target RPE-6 than -2. Responses were not affected by gender or production sequence. CONCLUSION Young female and male children were able to use the OMNI Scale to self-regulate short-duration intermittent cycle exercise intensity.

Exercise considerations for the sedentary, overweight adult

JAKICIC, J. M., and K. I. GALLAGHER. Exercise considerations for the sedentary, overweight adult. Exerc. Sport Sci. Rev., Vol. 31, No. 2, pp. 91–95, 2003. The significant rise in the prevalence of overweight and obesity has increased the importance of addressing this significant public health problem. Exercise appears to be an important factor for addressing the obesity epidemic. This review will focus on the role of exercise in the management of body weight and factors that should be considered when prescribing exercise to overweight adults.

Self-Monitoring: Influencing Effective Behavior Change in Your Clients

B ehavior change is a difficult process. As a health/ fitness professional, assisting clients with behavior change can be particularly challenging because client interaction is often limited. Many times, these meetings are not sufficient to target both eating and exercise behaviors and address the many barriers clients face. Because many health behaviors need to be targeted outside of these meetings, finding ways to track progress also is necessary to successfully provide clients with appropriate feedback and direction. Thus, teaching clients to self-monitor is an effective strategy for targeting both eating and exercise behavior change. Self-monitoring allows you to review your clients’ current eating and exercise behaviors, identify what needs to be modified so clients can reach their personal health/fitness goals, and provide feedback. By definition, self-monitoring is ‘‘the systematic observation and recording of target behavior’’ (1) and has been described as the most effective technique and the ‘‘cornerstone’’ of behavioral treatments for weight loss (2). Self-monitoring increases a client’s self-awareness, and this has been shown to positively influence eating and exercise behaviors (3). Several weight loss studies have shown that the more consistent participants were at self-monitoring and the more self-monitoring diaries were completed, the greater was the weight loss (4–6). In a review of studies, D.S. Kirschenbaum, Ph.D., determined that consistency is best defined as recording at least 75% of eating and exercise behaviors (7). This relationship also has been found in high-risk situations. In a study examining weight change during the holiday season, only the most consistent self-monitors lost weight (8). Although self-monitoring is considered to be a valuable tool for behavior change, it does require the consideration of several factors to be applied and used appropriately with your clients. Teaching your client to effectively and consistently self-monitor is a process that is dependent upon the client’s personality, goals, and knowledge regarding his or her behavior. Taking individual differences into account, your goal as the health/fitness professional should be to ‘‘help clients be the best self-monitors they can be’’ (8). As a guide, you can use the following ‘‘Four Ps of Self-Monitoring’’ to determine the best self-monitoring fit for your clients.

Effect of exercise duration and intensity on weight loss in overweight, sedentary women: A randomized trial

To test the hypothesis that longer and more intense exercise will enhance long-term weight loss, 201 sedentary women 27 to 40 years of age were enrolled in a randomized trial. The participants, whose baseline body mass index ranged from 27 to 40 kg/m 2 , were in a university-based weight control program. They were assigned to 1 of 4 groups that exercised at moderate or vigorous intensity for a moderate to long duration. Estimated energy expenditure was 1000 or 2000 kcal per week. All women were asked to reduce their energy intake to 1200 to 1500 kcal per day and their dietary fat intake to 20% to 30% of total energy intake. Nearly 95% of participants completed 12 months in the study. All participants were sedentary at the outset, exercising less than 3 days per week for less than 20 minutes. They were instructed to exercise, unsupervised, for 5 days a week, primarily by walking; motorized treadmills were provided. Bouts of exercise lasting at least 10 minutes were prescribed in terms of both percentage of age-predicted maximal heart rate and perceived exertion using the Borg scale. The women attended an average of 79% of group sessions in the first 6 months and 71% over the entire 12-month study period. Mean weight loss was significant in all groups, ranging from 8.9 kg with long-lasting vigorous exercise to 6.3 kg with moderate exercise of moderate duration. There were no significant between-group differences. Mean cardiorespiratory fitness also increased significantly in all groups, most markedly (22%) with vigorous, high-duration exercise. The least improvement, an increase of 13.5%, was in the group exercising at moderate intensity for a moderate time. Again, there were no differences between groups. Weight loss at 12 months correlated with the level of physical activity at both 6 and 12 months. Women exercising less than 150 minutes per week lost a mean of 4.7% body weight, contrasting with 13.6% for those exercising at least 200 minutes per week. There were no significant group differences in energy intake. The authors recommend that sedentary adults who are overweight begin by exercising at moderate intensity for at least 150 minutes per week. When appropriate, higher exercise levels should be adopted, aiming at an hour a day as advised by the Institute of Medicine.