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Biomedical subjects

J M Jakicic

Publications and source records attributed to J M Jakicic.

At least 19 recordsLinked to original sources

Exercise attitudes and behaviors among persons in treatment for alcohol use disorders.

The present study investigated self-reported exercise behaviors and exercise-related attitudes in a sample (N = 105) of adults in treatment for alcohol use disorders (AUD) (abuse or dependence). Slightly less than half (47%) of participants reported engaging in regular physical exercise (3 times per week or more). Level of alcohol dependence was not significantly associated with level of physical exercise activity. Level of nicotine dependence was significantly and negatively associated with physical activity level. Nicotine dependence and level of depressive symptoms were both significantly negatively associated with self-efficacy for physical exercise (SPE). Exercise self-efficacy mediated the relationship between nicotine dependence and physical activity level. Tension and stress reduction were among the most strongly endorsed of the perceived benefits of physical activity. Other perceived benefits included more positive outlook and increased self-esteem. Financial costs associated with exercise, lack of motivation, and time constraints were among the most common perceived barriers to exercise in this sample. Together, these preliminary data indicate that exercise-based interventions are may be well-received by those early in recovery from AUDs.

Adolescent↗

Do African-American and Caucasian overweight women differ in oxygen consumption during fixed periods of exercise?

OBJECTIVE: To examine whether there are ethnic differences in oxygen consumption during fixed periods of exercise. DESIGN: Cross-sectional. SUBJECTS: Twenty-seven African-American and 120 Caucasian overweight adult women (body mass index=32.8+/-4.1 kg/m(2), age=36.7+/-5.6 y) prior to initiating a weight loss program. MEASUREMENTS: Measurement of oxygen consumption occurred during four stages of a graded exercise test, with body composition assessed by dual-energy X-ray absorptiometry. RESULTS: There were no significant differences between overweight African-American and Caucasian women for absolute oxygen consumption or oxygen consumption adjusted for either body weight or fat-free mass across four levels of a submaximal graded exercise test. CONCLUSION: The results from this study suggest that African-American and Caucasian women do not differ in energy expenditure during fixed workloads of exercise, suggesting that this may not contribute to differences in energy balance and body weight regulation between women in these two ethnic groups.

Absorptiometry, Photon↗

American College of Sports Medicine position stand. Appropriate intervention strategies for weight loss and prevention of weight regain for adults.

In excess of 55% of adults in the United States are classified as either overweight (body mass index = 25-29.9 kg.m(-2)) or obese (body mass index > or = 30 kg.m(-2)). To address this significant public health problem, the American College of Sports Medicine recommends that the combination of reductions in energy intake and increases in energy expenditure, through structured exercise and other forms of physical activity, be a component of weight loss intervention programs. An energy deficit of 500-1000 kcal.d-1 achieved through reductions in total energy intake is recommended. Moreover, it appears that reducing dietary fat intake to <30% of total energy intake may facilitate weight loss by reducing total energy intake. Although there may be advantages to modifying protein and carbohydrate intake, the optimal doses of these macronutritents for weight loss have not been determined. Significant health benefits can be recognized with participation in a minimum of 150 min (2.5 h) of moderate intensity exercise per week, and overweight and obese adults should progressively increase to this initial exercise goal. However, there may be advantages to progressively increasing exercise to 200-300 min (3.3-5 h) of exercise per week, as recent scientific evidence indicates that this level of exercise facilitates the long-term maintenance of weight loss. The addition of resistance exercise to a weight loss intervention will increase strength and function but may not attenuate the loss of fat-free mass typically observed with reductions in total energy intake and loss of body weight. When medically indicated, pharmacotherapy may be used for weight loss, but pharmacotherapy appears to be most effective when used in combination with modifications of both eating and exercise behaviors. The American College of Sports Medicine recommends that the strategies outlined in this position paper be incorporated into interventions targeting weight loss and the prevention of weight regain for adults.

Adult↗

Behavioral science research in diabetes: lifestyle changes related to obesity, eating behavior, and physical activity.

Lifestyle factors related to obesity, eating behavior, and physical activity play a major role in the prevention and treatment of type 2 diabetes. In recent years, there has been progress in the development of behavioral strategies to modify these lifestyle behaviors. Further research, however, is clearly needed, because the rates of obesity in our country are escalating, and changing behavior for the long term has proven to be very difficult. This review article, which grew out of a National Institute of Diabetes and Digestive and Kidney Diseases conference on behavioral science research in diabetes, identifies four key topics related to obesity and physical activity that should be given high priority in future research efforts: 1) environmental factors related to obesity, eating, and physical activity; 2) adoption and maintenance of healthful eating, physical activity, and weight; 3) etiology of eating and physical activity; and 4) multiple behavior changes. This review article discusses the significance of each of these four topics, briefly reviews prior research in each area, identifies barriers to progress, and makes specific research recommendations.

Behavior Therapy↗

Standardized scaling procedures for rating perceived exertion during resistance exercise.

The purpose of this project was to determine the validity of standardized Borg scale instructions and scale anchoring procedures to measure active muscle rating of perceived exertion and overall rating of perceived exertion during resistance exercise. Anchoring procedures were determined for each of 7 exercises before the completion of 2 counterbalanced experimental trials. In one trial, subjects lifted 90% of 1 repetition maximum (1RM) 5 times. In the other, subjects lifted 30% of 1RM 15 times. Adjusted R2 and SEMs were used to determine linearity of Borg 15-category scale responses with respect to repetitions at equal work increments for both the group and the sum of the individuals. Both group and individual responses had high adjusted R2 and low SEM values. These results suggest that the current scaling instructions used with the Borg 15-category scale are valid for use during resistance exercise.

Adult↗

Effects of intermittent exercise and use of home exercise equipment on adherence, weight loss, and fitness in overweight women: a randomized trial.

CONTEXT: Enhancing participation in long-term exercise may translate into improved long-term weight loss in overweight adults. OBJECTIVES: To compare the effects of intermittent with traditional continuous exercise on weight loss, adherence, and fitness, and to examine the effect of combining intermittent exercise with that using home exercise equipment. DESIGN: Randomized trial from September 1996 through September 1998. SETTING AND PARTICIPANTS: A total of 148 sedentary, overweight (mean [SD] body mass index, 32.8 [4.0] kg/m2) women (mean [SD] age, 36.7 [5.6] years) in a university-based weight control program. INTERVENTIONS: Eighteen-month behavioral weight control program with 3 groups: long-bout exercise (LB), multiple short-bout exercise (SB), or multiple short-bout exercise with home exercise equipment (SBEQ) using a treadmill. MAIN OUTCOME MEASURES: Body weight, body composition, cardiorespiratory fitness, and exercise adherence. RESULTS: Of 148 subjects, 115 (78%) completed the 18-month program. At 18 months, mean (SD) weight loss was significantly greater in subjects in the SBEQ group compared with subjects in the SB group (-7.4 [7.8] kg vs -3.7 [6.6] kg; P<.05). Mean (SD) weight loss for subjects in the LB group (-5.8 [7.1] kg) was not significantly different than for subjects in the SB or SBEQ groups. Subjects in the SBEQ group maintained a higher level of exercise than subjects in both the SB and LB groups (P<.05) at 13 to 18 months of treatment. All groups showed an increase in cardiorespiratory fitness from baseline to 18 months, with no difference between groups. Mean (SD) weight loss at 18 months was significantly greater in individuals exercising more than 200 min/wk throughout the intervention (-13.1 [8.0] kg) compared with individuals exercising 150 to 200 min/wk (-8.5 [5.8] kg) or less than 150 min/wk (-3.5 [6.5] kg) (P<.05). CONCLUSIONS: Compared with the LB group, subjects in the SB group did not experience improved long-term weight loss, exercise participation, or cardiorespiratory fitness. Access to home exercise equipment facilitated the maintenance of SB, which may improve long-term weight loss. A dose-response relationship exists between amount of exercise and long-term weight loss in overweight adult women.

Adult↗

The accuracy of the TriTrac-R3D accelerometer to estimate energy expenditure.

PURPOSE: This study examined the reliability and validity of the TriTrac-R3D triaxial accelerometer to estimate energy expenditure during various modes of exercise. METHODS: Twenty subjects (age = 21.5+/-3.4 yr; body mass index = 23.3+/-3.6 kg x m(-2)) performed five exercises (treadmill walking, treadmill running, stepping, stationary cycling, and slideboard), with each lasting 20-30 min and workload increased at 10-min intervals. To test the inter-TriTrac reliability, two TriTrac-R3D accelerometers were worn during each exercise period, and to examine validity, a simultaneous measurement of energy expenditure was made using indirect calorimetry (SensorMedics 2900 Metabolic Cart). RESULTS: Results showed a significant correlation between the two TriTrac-R3D accelerometers during all exercises. The difference in estimated energy expenditure between the two accelerometers during the walking, stepping, and slideboard exercises was less than 1 kcal x min(-1) but statistically significant (P<0.05). There was also a significant correlation between energy expenditure estimated by each of the TriTrac-R3D accelerometers and indirect calorimetry during walking, running, stepping, and slideboard exercise (P<0.05). The interaction of Method x Workload was significant (P<0.05) for each exercise, indicating that the TriTrac-R3D underestimates energy expenditure and that the magnitude of this underestimation increases as workload increases. CONCLUSIONS: Therefore, energy expenditure estimated via triaxial accelerometry does not increase with increasing workloads. These results suggest that there are limitations to using triaxial accelerometry to quantify energy expenditure.

Adolescent↗

Clinic-based vs. home-based interventions for preventing weight gain in men.

OBJECTIVE: Weight gain occurs frequently in men aged 25-40. This study compared the effectiveness of a clinic-based and a home-based intervention with a no-treatment control group in preventing this weight gain. RESEARCH METHODS AND PROCEDURES: Men (n=67)-aged 25 to 40, sedentary, with a body mass index of 22 to 30, recruited from the University of Pittsburgh-were randomly assigned to 4-month treatments focused on increasing aerobic exercise and reducing fat intake through a clinic-based (CB) or a home-based (HB) program, or to a delayed-treatment control group. Subjects were reassessed at 4 months. RESULTS: Adherence and outcome did not differ significantly between the CB and HB programs, except that CB subjects recorded their food intake more frequently, and a greater number of CB subjects achieved a total of 120 miles of exercise over the 4 months. Subjects in the two intervention conditions combined lost significantly more weight (-1.6+/-2.5 kg) than control subjects, who gained 0.2+/-1.9 kg (p<0.01); this effect of treatment was seen primarily in men with a body mass index of 27 to 30 (-2.7 kg for CB and HB combined vs. + 1.5 kg for control). Treated subjects also had somewhat greater improvements in body composition, aerobic fitness, and weekly energy expenditure than controls, although these differences did not reach significance. DISCUSSIONS: Both CB and HB intervention show promise in preventing weight gain in young men, especially in those who are slightly overweight. Larger studies, using more representative samples of young men, appear warranted.

Adult↗

Lifestyle physical activity interventions. History, short- and long-term effects, and recommendations.

INTRODUCTION: Lifestyle physical activity interventions have resulted in response to the public health problem of promoting regular amounts of physical activity to the majority of U.S. adults who remain inadequately or completely inactive. These lifestyle interventions allow a person to individualize his/her physical activity programs to include a wide variety of activities that are at least of moderate intensity and to accumulate bouts of these activities in a manner befitting his/her life circumstances. METHODS: We reviewed the history of lifestyle physical activity interventions and defined lifestyle physical activity based on this review. We located 14 studies that met this definition. RESULTS: Lifestyle physical activity interventions are effective at increasing and maintaining levels of physical activity that meet or exceed public health guidelines for physical activity in representative samples of previously sedentary adults and obese children. The majority of these interventions have been delivered by face-to-face contact in small groups, which limits their public health impact. However, a small number of studies demonstrate that these interventions can be delivered by mail and telephone, which may enhance their generalizability. Most of these studies utilized behavior change theories such as Social Cognitive Theory, the Transtheoretical Model, and Behavior Learning to shape the interventions. Lifestyle interventions aimed at modifying the environment, such as signs posted to increase stair climbing, also have been shown to be effective over the short term. CONCLUSIONS: The major issues concerning lifestyle physical activity interventions are: (1) testing their ability to be implemented on a large scale; (2) examining cost-effectiveness for different modes of delivery; and (3) researching the efficacy in populations such as the elderly, minorities, economically disadvantaged, and individuals with concurrent disease. More studies aimed at manipulating the environment to increase physical activity need to be tested over periods of one year or longer. It is possible that lifestyle interventions could be integrated and delivered by new technologies such as interactive computer-mediated programs, telephone, or computer web-based formats. All of these recommended approaches should utilize valid and reliable measures of physical activity and should examine the health effects, particularly on a longitudinal basis. Basic dose-response studies in controlled settings also are needed to help us understand the health effects of accumulated moderate intensity activity.

Adult↗

Differences in resting energy expenditure in African-American vs Caucasian overweight females.

OBJECTIVE: The purpose of this study was to examine differences in both resting energy expenditure (REE) and respiratory quotient (RQ) between overweight African-American and Caucasian women of comparable age and body mass index (BMI). DESIGN: Cross-sectional. SUBJECTS: REE was assessed in 41 women (22 African-American and 19 Caucasian) who were recruited to participate in this study. The African-American women were aged 36.4+/-5.7 y with a BMI of 32.6+/-5.4 kg/m2, and the Caucasian women were aged 35.4+/-5.7 y with a BMI of 31.3+/-3.4 kg/m2. MEASUREMENTS: Body composition was assessed using dual energy x-ray absorptiometry (DEXA). REE was assessed via the dilution technique following an overnight fast. RESULTS: REE was lower in African-Americans (7279+/-825 kJ/d) compared to Caucasians (7807+/-854 kJ/d) (P = 0.051). Analysis of covariance showed that REE remained significantly lower in African-American women after correcting for body weight and lean body mass. There was no effect of ethnicity on RQ. CONCLUSION: These results indicate that there is a significant difference in REE between Caucasian and African-American overweight women. This difference in REE may contribute to the higher rates of obesity found in the African-American population. This difference may also partially explain the smaller weight losses typically seen in African-American women when compared to Caucasian women enrolled in a weight loss program.

Adult↗

Bioelectrical impedance analysis to assess body composition in obese adult women: the effect of ethnicity.

OBJECTIVE: To examine whether the accuracy of bioelectrical impedance analysis (BIA) to estimate body composition in overweight women is affected by the ethnicity of the individuals. DESIGN: Cross-sectional design to compare body composition estimated by BIA to body composition measured by dual energy x-ray absorptiometry (DEXA), which was the reference method. SUBJECTS: One hundred twenty three overweight women participated in this study, of which 43 women were African-American (aged 37.2+/-5.6 y; BMI, 32.3+/-4.9 kg/m2) and 80 were Caucasian (aged 36.1+/-5.7 y; BMI, 31.9+/-3.5 kg/m2). MEASUREMENTS: Body composition was estimated from BIA using both a generalized and an obesity-specific equation. These estimations were compared to body composition measured by DEXA, which was the reference method. RESULTS: The generalized BIA equation underestimated lean body mass (LBM) by 2.6+/-3.1 kg in Caucasian women and 0.4+/-3.2 kg in African-American women, with the difference between the ethnic groups being significant (P < 0.001). The obesity-specific equation underestimated LBM in Caucasians by 0.9+/-3.1 kg and overestimated LBM in African-Americans by 1.2+/-2.8 kg (P < 0.001). An ethnic-specific equation is proposed, and cross-validation of this equation indicates that it provides a reasonable estimate of body composition in overweight women. CONCLUSIONS: The accuracy of BIA to estimate body composition appears to be affected by the ethnicity of the individual. Therefore, an ethnic-specific equation for overweight women is proposed. However, further validation of this prediction model in an ethnically diverse population is necessary.

Absorptiometry, Photon↗

Accuracy of self-reported exercise and the relationship with weight loss in overweight women.

PURPOSE: The purpose of this study was to compare self-reported exercise to a more objective measurement of exercise (i.e., Tri-Trac Accelerometer) and to assess whether there is a difference in weight loss between individuals who under- and over-report their exercise. METHODS: Fifty overweight females (BMI = 34.0 +/- 4.2 kg.m-2) who were participating in a behavioral weight control program were included in this study. Subjects were randomly assigned to a long-bout or a short-bout exercise condition, with both groups instructed to exercise 30 min.day-1 on 5 d.wk-1 for a period of 20 wk. The long-bout group was to exercise in one continuous session (e.g., one 30-min session per day), whereas the short-bout group was to divide the exercise into multiple 10-min sessions (e.g., three 10-min sessions per day). Subjects recorded their exercise in a daily exercise log and wore a Tri-Trac accelerometer for a 1-wk period to validate self-reported exercise bouts. RESULTS: Results showed that approximately 45% of the women over-reported the amount of exercise that they performed, and this did not differ between the long-bout and short-bout groups. Women who over-reported their exercise had significantly poorer weight loss across the 20-wk program than women who under-reported their exercise (6.3 +/- 3.6 kg vs 9.4 +/- 5.2 kg). CONCLUSIONS: The results of this study suggest that overweight women who over-report their exercise will have poorer weight loss while enrolled in a behavioral weight loss program compared with others enrolled in the program, and the Tri-Trac Accelerometer may be useful in identifying individuals who inaccurately report the amount of their exercise. The ability to classify individuals as either over- or under-reporters of their exercise may be helpful to weight loss therapists and lead to more successful treatment for obesity.

Adult↗

Lifestyle intervention in overweight individuals with a family history of diabetes.

OBJECTIVE: To assess the effect of lifestyle intervention over 2 years on changes in weight, coronary heart disease (CHD) risk factors, and incidence of diabetes in overweight individuals with a parental history of diabetes. RESEARCH DESIGN AND METHODS: Participants (n = 154), who were 30-100% over ideal body weight, had one or both parents with diabetes, and were currently nondiabetic, were randomly assigned to 2-year treatments focused on diet (decreasing calories and fat intake), exercise (goal of 1,500 kcal/week of moderate activity), or the combination of diet plus exercise or to a no-treatment control group. Subjects were reassessed at 6 months, 1 year, and 2 years. RESULTS: At 6 months, the groups differed significantly on measures of eating, exercise, and fitness; weight losses in the diet and diet-plus-exercise groups were significantly greater than in the exercise and control conditions. Weight losses were associated with positive changes in CHD risk factors. After 6 months, there was gradual deterioration of behavioral and physiological changes, so that at 2 years, almost no between-group differences were maintained. Differences between groups in risk of developing diabetes were of borderline significance (P = 0.08). Strongest predictors were impaired glucose tolerance at baseline, which was positively related to risk of developing diabetes, and weight loss from baseline to 2 years, which was negatively related; in all treatment groups, a modest weight loss of 4.5 kg reduced the risk of type 2 diabetes by approximately 30% compared with no weight loss. CONCLUSIONS: Although initially successful, the interventions studied here were not effective in producing long-term changes in behavior, weight, or physiological parameters. However, weight loss from 0 to 2 years reduced the risk of developing type 2 diabetes. Since modest weight loss significantly reduced risk of type 2 diabetes, further research is needed to determine how best to increase the percentage of subjects achieving at least a modest weight loss.

Adult↗

The effects of long-term, moderate intensity, intermittent exercise on aerobic capacity, body composition, blood lipids, insulin and glucose in overweight females.

OBJECTIVE: To test the hypotheses that the accumulation of 30 min of moderate intensity, intermittent exercise, 5d/week-1, for 32 weeks, will increase aerobic capacity, alter body composition and improve blood lipids, insulin and glucose. Secondly, to identify individuals who may respond to moderate intensity, intermittent exercise. SUBJECTS: Thirteen sedentary, moderately obese females, aged 43 +/- 11 (y), body mass index (BMI) 32.7 +/- 7.7 (kg/M2), body fat 40.6 +/- 8.8 (%), VO2max 24.0 +/- 4.6 (ml/kg-1/min-1). MEASUREMENTS: Aerobic capacity, body composition, blood lipids, fasting insulin and glucose, energy intake. RESULTS: Group data showed no significant changes for aerobic capacity, body composition, blood lipids, insulin or glucose. However, 7 of the 13 subjects increased aerobic capacity, lost fat weight and improved insulin. Adherence to the exercise regimen was excellent with 82.6 +/- 10.0% of the exercise completed. CONCLUSIONS: Moderate intensity, intermittent exercise for a total of 30 min, 5d/week,-1 for 32 weeks duration, was not a sufficient stimulus to significantly increase aerobic capacity, and alter weight, body composition or improve blood lipids, insulin or glucose for the entire group. However, those subjects who increased aerobic capacity and decreased fat weight were significantly older, had lower maximal aerobic capacity and greater body fat at baseline compared to the six subjects who did not increase aerobic capacity and decrease fat weight. For both groups, moderate intensity, intermittent exercise showed excellent adherence and this may be a useful model for future research studies.

Adult↗

The effects of health beliefs on weight loss in individuals at high risk for NIDDM.

OBJECTIVE: To determine whether perceived risk and other health beliefs held by individuals at high risk for developing NIDDM predict weight loss and behavior change during a behavioral weight loss program to reduce the risk of NIDDM. RESEARCH DESIGN AND METHODS: Health beliefs and objective risk factors for diabetes were examined in 154 overweight men and women with a family history of NIDDM. The effects of these factors on adherence, dietary intake, weight loss, and changes in glucose levels were examined in a subset of 79 of these subjects who participated in a 2-year behavioral weight control program. RESULTS: Those subjects who perceived themselves at highest risk of developing diabetes had a stronger family history of the disease and were more likely to be women than subjects considering themselves at more moderate risk. These participants also rated diabetes as a more serious disease, but were less likely to believe that weight loss would lower their risk. None of these health beliefs were related to attendance at meetings, dietary intake, weight loss, or fasting glucose, but higher perceived seriousness predicted larger reductions in BMI at 1 year. Of the objective risk factors for NIDDM, higher baseline BMI predicted larger weight losses throughout the program, and a stronger family history of diabetes was related to greater weight regain after an initial weight loss. CONCLUSIONS: Perceived risk of developing diabetes and other health beliefs did not predict performance in a behavioral weight loss program. These data suggest that efforts to modify health beliefs by educating high-risk individuals about their risk and benefits of weight loss may not be effective in improving long-term weight loss results.

Adult↗

Weight cycling, psychological health, and binge eating in obese women.

This study examined the relationship between weight cycling and psychological health in 120 obese women. Weight cycling was defined in 2 ways by retrospective self-report: total lifetime weight loss and total number of weight cycles > or = 20 lbs (> or = 9.07 kg). Psychological self-report measures assessed psychiatric symptoms, eating behavior, mood, stress, and perceptions of physical health. Of the 52 associations between weight cycling and psychological parameters, 8 were significant, with the most consistent association being between weight cycling and binge eating. Binge eating was also strongly associated with psychological distress, as found in previous studies. After adjusting for binge eating, however, weight cycling was independently related to only one of the psychological measures: perceived physical health.

Adult↗

Prescription of exercise intensity for the obese patient: the relationship between heart rate, VO2 and perceived exertion.

OBJECTIVE: It has been suggested that relative heart rate reserve (% HRR), relative oxygen uptake (% VO2peak), and rating of perceived exertion (RPE) can be used interchangeably to prescribe exercise intensity. The purpose of this study was to examine the relationship between % HRR, % VO2peak, and RPE in obese females prior to and following substantial weight loss. SUBJECTS: 122 obese females (% Body fat = 45.9 +/- 5.0%) who participated in a weight loss intervention program. METHOD: Functional aerobic capacity was measured at baseline and following 12 weeks of exercise training and weight loss using a multi-stage Modified Balke treadmill protocol. The VO2, heart rate (HR), and RPE were measured at each stage, with VO2 and HR data converted to the percentages of the peak levels attained. These multi-stage data were then analyzed using mixed-model regression procedures to examine the relationship between % HRR, % VO2, and RPE. RESULTS: With RPE as the dependent variable, results indicated that % HRR and % VO2, corresponded to RPE values consistent with existing guidelines (70% = 13-14 RPE), and this was true for analyses performed at baseline and following weight loss. Further, baseline results indicated that % HRR and % VO2 corresponded to similar levels of exercise intensity (40-70% HRR = 40-70% VO2peak). However, following weight loss, % HRR represented a higher level of intensity than its corresponding % VO2peak. CONCLUSIONS: The results of this study suggest that RPE can be used as subjective marker of exercise intensity in an obese female population. However, despite adhering to existing guidelines prior to weight loss, there may be a discrepancy in the relationship between % HRR and VO2max following severe weight loss, possibly due to the decrease in resting HR following exercise training and weight loss. These findings directly impact the prescription and monitoring of exercise intensity for obese patients.

Adult↗

Prescribing exercise in multiple short bouts versus one continuous bout: effects on adherence, cardiorespiratory fitness, and weight loss in overweight women.

OBJECTIVE: To investigate whether prescribing exercise in several short-bouts versus one long-bout per day would enhance exercise adherence, cardiorespiratory fitness, and weight loss in overweight adult females in a behavioral weight control program. DESIGN: Randomized controlled trial with subjects randomized to either a short-bout exercise group (SB, n = 28, age = 40.4 +/- 5.9 yrs) or a long-bout exercise group (LB, n = 28, age = 40.9 +/- 7.3 yrs), with subjects followed for a period of 20 weeks. Both groups were instructed to exercise 5 days per week with exercise duration progressing from 20 to 40 min per day. The LB group performed one exercise bout per day, whereas the SB group performed multiple 10 min bouts of exercise per day. The recommended caloric intake for all subjects was 5022-6277 kJ/day (1200-1500 kcal/day), with fat reduced to 20% of caloric intake. SUBJECTS: Fifty-six obese, sedentary females (BMI = 33.9 +/- 4.1 kg/m2). MEASUREMENTS: Exercise participation was assessed from self-reported diaries and Tri-Trac Accelerometers. Cardiorespiratory fitness was assessed using a submaximal cycle ergometer test. RESULTS: Exercising in multiple short-bouts per day improved adherence to exercise: the SB group reported exercising on a greater number of days (mean +/- s.d. = 87.3 +/- 29.5 days vs 69.1 +/- 28.9 days; P < 0.05) and for a greater total duration (223.8 +/- 69.5 min/week vs 188.2 +/- 58.4 min/week; P = 0.08) than the LB group. Predicted VO2Peak increased by 5.6% and 5.0% for the LB and SB groups, respectively (P < 0.05). There was a trend for the weight loss to be greater in the SB group (-8.9 +/- 5.3 kg) compared to the LB group (-6.4 +/- 4.5 kg; P < 0.07). CONCLUSION: These results suggest that short-bouts of exercise may enhance exercise adherence. Short-bouts of exercise may also enhance weight loss and produce similar changes in cardiorespiratory fitness when compared to long-bouts of exercise. Thus, short-bouts of exercise may be preferred when prescribing exercise to obese adults.

Adult↗