Abstract
Background
The mode and duration of exercise necessary to change body composition and reduce weight remains debatable. Menopause results in hormonal changes that preclude weight loss. This randomized pilot study compared the effects of short-duration, high-intensity interval training and traditional exercise on anthropometric and body composition measurement changes in post-menopausal women.
Objective
To compare the effects of short-duration, high-intensity interval training and traditional methods of exercise (walking) on anthropometric, body composition and body weight change over a 12-week period.
Main outcome measures
Subjects (N = 18) were post-menopausal, sedentary female volunteers, randomly assigned into one of two exercise groups. Both groups exercised five out of seven days for 12 weeks. The resistance group (n = 8) (54.3 ± 7.3 years; BMI = 28.0 ± 2.1 kg/m2; mean ± SD) exercised for 15.0 ± 3.5 min, which consisted of five different exercise routines including upper and lower extremity, a cardio segment, yoga and abdominal exercises. The walkers (n = 10) (56.6 ± 5.2 years; BMI = 29.2 ± 2.6 kg/m2; mean ± SD) exercised for 40.0 ± 5.0 min at 65% of their age-predicted maximum heart rate. Relative (%) body fat was measured via DEXA scan, along with five anthropometric measurements, all of which were taken prior to and after 12 weeks. Independent sample t-tests were probed for differences, p ≤ 0.05.
Results
No statistically significant changes were determined between the groups for pre-and post-measurements.
Conclusions
The outcomes of this study provide a foundation for future comparisons of short-duration high-intensity interval training exercise and traditional exercise, or walking, on anthropometric and body composition measurement changes in sedentary, overweight, post-menopausal females over a 12-week period.
Keywords
Introduction
It is well understood that an increase in physical activity is necessary for weight loss and maintenance of body weight. 1 Physical activity is the contraction of skeletal muscles that results in energy expenditure increases, while exercise is a type of structured physical activity with repetitive bodily movements intended to improve or maintain one or more components of physical fitness. 2 Traditional exercise, such as walking, has been associated with effects on body composition, favouring a decrease in fat mass (FM) and an increase in fat-free mass (FFM). Active, overweight individuals have decreased rates of morbidity and mortality as compared to sedentary, overweight individuals. 3 According to the American College of Sports Medicine, 4 exercise is an important component of a weight-control program and beneficial for overweight persons.
There is a growing body of evidence that indicates that short-duration, high-intensity interval training (HIIT), a form of progressive resistance training, might effectively replace traditional, endurance-based training and result in similar or even better physiological outcomes for both healthy and diseased individuals.5,6 Such findings are of importance, as a primary reason for not exercising is a ‘lack of time’. Although there is limited research on HIIT, recent work indicates that the application of HIIT exercise may have promising health benefits, such as an increase in strength or FFM and reduction in FM,3,7,8 in both younger and older populations and in males and females. This type of training may result in physiological changes that are comparable to moderate-intensity endurance training and may produce positive changes for overweight individuals, with additional benefits in reducing chronic disease.3,9
In addition, it is well documented that the hormonal changes resulting from menopause or natural aging often impede weight loss. 10 In order to reduce the risk of obesity and associated co-morbidities, such as heart disease and stroke, both of which increase during menopause, exercise is highly encouraged for post-menopausal women. 11
Purpose
The purpose of this pilot study was to compare the effects of short-duration HIIT via the ‘10-Minute Trainer’ fitness DVD workout program, 12 designated as the HIIT exercise, with a traditional walking exercise program. Results compared anthropometric and body composition measurement changes in overweight, post-menopausal women over a 12-week period.
Methods
Participant criteria and recruitment
The study sample (N = 18) comprised female employees recruited from two universities in the mid-Atlantic region of the United States. Participants were sedentary, post-menopausal women who were 20 pounds overweight, with a body mass index (BMI) between 25.0 and 34.9. An upper age limit of 65 years was used to minimize any age-related co-morbidities. The term sedentary was defined as having no structured exercise routine within the past 6 months, and post-menopausal was defined as amenorrhea for 12 consecutive months. Volunteers were excluded if they reported a heart condition, lost consciousness during activity or experienced chest pain during periods of rest or activity on the Physical Activity Readiness Questionnaire. 13 They also were excluded if they were unable to walk approximately two blocks without stopping; were concurrently participating in an exercise and/or weight loss program; or were taking medicine(s) for weight loss. They were also excluded if they had gastric surgery for weight loss or had lost ≥5% of body weight within six months of the study. Additional exclusion criteria included reported joint problems, psychological disease or intention to move outside the area within the time frame of the intervention. Participants on prescribed medicines required written physician consent to participate.
Participants were recruited for a four-month period at each university through faculty and staff email list-serve announcements, which informed prospective participants of the available research study orientation sessions that took place on both campuses. After completion of the orientation sessions, eligible participants signed consent forms that were approved by both university Institutional Review Boards.
Project design
Participants were randomized into one of two treatment groups. A coin toss was used to randomize the participants, with ‘heads’ directed to the Standard Condition, walking (Group I) and ‘tails’ directed to the Short-duration Condition or HIIT (Group II). Participants were informed of their group assignment after the completion of their initial assessment, designated as baseline (week 0). All participants agreed to only engage in the exercise condition assigned for the duration of the study, while activities of daily living were encouraged to remain unchanged, as the study was designed to replicate bimorphic data.
Intervention
Participants in the Standard Condition, walking (Group I) were assigned an exercise prescription of walking at an intensity level of 65% of their age-predicted maximal heart rate, a moderate intensity level for this population. 4 For the first week of the intervention, participants were instructed to walk 10 min each day (5 days/week) for a weekly goal of 50 exercise minutes. Five minutes were added each day, per week of the intervention (i.e. week 2 included 15 min each day [5 days/week] for a weekly goal of 75 exercise minutes; week 3 included 20 min per day [5 days/week] for a weekly goal of 100 exercise minutes, until a total goal of 200 min per week was achieved by Week 6). From weeks 6 to 12, participants were instructed to exercise 40 min each day (5 days/week), for a weekly goal of 200 exercise minutes. Exercise intensity was monitored via a Sportline SOLO 915 heart rate and calorie wristband device. 14
The Short-duration Condition, HIIT (Group II) exercise prescription was derived from the ‘10-min Trainer’ DVD set. 12 Participants were instructed to exercise 10 min each day (5 days/week) for 12 weeks using this training video as their sole exercise program. The DVD set included five different exercises: ‘total body’, ‘cardio’, ‘lower body’, ‘abs’ and ‘yoga flex’ components. One session, or 10 min of exercise, was completed each day in random order, with five different exercises completed weekly. The DVD exercises were one minute in length, with 10 different exercises within each segment.
Compliance was monitored through weekly online check-ins with one of the investigators. The check-ins were required for participation and provided a venue for participants to offer feedback regarding the interventions. The check-ins also allowed for self-monitoring assessment for each participant. 15
Incentives
Participants received an incentive of $25 upon completion of each assessment at baseline, or week 0, and weeks 6 and 12, for a total of $75, for the duration of the study. Each participant also received a personal copy of the ‘10-min Trainer’ DVD set. The DVD set was provided at the outset of the study for participants in the Short-duration Condition, HIIT (Group II) and after the completion of the final assessment for participants in the Standard Condition, walking (Group I).
Data collection and measurements
All assessments were completed in a university human physiology lab by a registered nurse. Data collection occurred at weeks 0, 6 and 12. Height and basic demographic information, which included age and gender, was obtained at week 0. Weight and five anthropometric circumference measures were taken at weeks 0, 6 and 12. These measurements included waist, hips, abdomen, biceps and thigh, with the latter two measured on the right side of the body for universal consistency purposes.
Body composition measurements included percentage of body fat (%BF), FM and FFM. Body composition was assessed at weeks 0 and 12 via the DEXA Scan (General Electric, Madison, WI), the gold standard in body composition measurement. 4 A separate consent form, that had IRB approval, was signed by all participants prior to the completion of the DEXA Scan. The test was performed by a registered nurse, certified and trained in DEXA Scan testing. The test required no injections, sedation, special diet or any other advanced preparation. The procedure took less than 30 min and required the patient to lie fully clothed on a padded table while the DEXA Scan beamed low-dose X-rays from two different sources toward the examined bones, the lower spine or hip. Two energy peaks were captured, one absorbed primarily by the soft tissue and the other by the bone. A computer program analysed the resulting images and calculated bone density based on the amount of radiation absorbed by the bone, i.e. the denser the bone, the more radiation absorbed. 4
Results
Statistical analyses were completed with IBM-SPSS for Windows, Version 21. 16 Initial t-tests confirmed the uniformity of both groups. Independent sample t-tests with an alpha of p ≤ 0.05 were completed and probed for anthropometric and body composition measurement changes between the two groups, with post-tests completed to confirm the findings. Comparisons within groups also were completed at a confidence level of p ≤ 0.05, using Bonferroni’s correction with an equivalency level of p ≤ 0.004.
Anthropometric Changes: Pre-Post Measurements and Changes between Groups.
HIIT: high-intensity interval training.
Body composition changes between groups.
BMI: body mass index; HIIT: high-intensity interval training.
Anthropometric changes within groups.
HIIT: high-intensity interval training.
Discussion
The results of this work indicate that, in both groups, four of the five anthropometric measurements showed decreases in waist, abdomen, hips and thigh, with an increase in the biceps measurements. The body composition data for both groups also resulted in decrease in body weight, %BF, FM and BMI as well as an increase in FFM. Further, a greater increase in FFM, with a greater decrease in %BF, was observed in the HIIT group compared to the walking group, but the changes were not statistically significant. The movement of all measurement changes for both groups indicated that the exercise interventions had an impact on anthropometric and body composition measurements, such that the changes moved in a direction supportive of reduced adiposity with an increase in FFM, both of which are indicative of positive changes for improved health. A possible explanation of a lack of statistical significance may have been the small sample size in both groups, with n = 10 in Group I, the Standard Condition and n = 8 in Group 2 or the short-duration, HIIT. Also, the duration of the study, i.e. 12 weeks may not have been enough time to substantiate significant statistical changes in this population, as other similar work indicated statistical significance with an exercise program design of 20 weeks. 17 Another possible explanation is that the hormonal changes that occur with menopause often preclude weight loss. 10
The overall compliance was 90%, with 18 of the 20 participants having completed the 12-week program. The two participants who withdrew from the study were both from the Short-duration Condition, HIIT (Group II). The withdrawal of these two participants may have been due to the greater physical challenge that the HIIT exercise program offered compared to that of a traditional walking exercise program. As noted, compliance was monitored through weekly check-ins with one of the researchers, and these weekly check-ins may have been instrumental in the high rate of compliance observed throughout the 12-week study. However, more work is needed to better determine if different modes and duration of exercise can result in significant changes in anthropometric and body composition measurements for sedentary, overweight, post-menopausal women.
Limitations/future research
Although this work is limited to anthropometric and body composition changes in post-menopausal women, it serves as a launching pad for future work within this population, who due to the natural processes of aging are at risk for multiple co-morbidities such as obesity, cardiovascular disease, osteoporosis and sarcopenia.10,11,18 Future research that could support the premise of a HIIT program as effective exercise for post-menopausal women may include measurements of sarcopenia along with examining metabolic markers such as insulin sensitivity and glucose uptake, along with measurements of aerobic capacity, as such work has shown promising results in younger male and female populations.17,19
A larger sample size would provide a better cross-section of the study population; however, there are no published works on post-menopausal women and HIIT exercise programs; thus, no preliminary data were available to calculate an effect size for this population. An increased length of study, i.e. greater than 12 weeks is suggestive to witness possible exercise-induced anthropometric and body composition changes. Additional comparative work with a study design that would include a HIIT group, a traditional exercise group and a non-exercise control group, along with women on hormone replacement therapy, would provide interesting comparisons.
Participants exercised independently and were required to check in on-line weekly for compliance purposes with one of the study researchers. Future work could include monitored exercise in a laboratory setting to ensure completion of the exercise intervention. Also, a program design inclusive of a dietary component with caloric restrictions and dietary analyses would more likely support significant differences between groups.
Conclusion
To date, this is the first work that has compared differences of continuous, traditional, aerobic exercise and HIIT exercise in sedentary, overweight, post-menopausal women. Four of the five anthropometric measurements resulted in decreased waist, abdomen, hips and thigh measurements, while biceps measurements increased. Although not statistically significant, a greater increase in FFM, with a greater decrease in %BF, was observed in the HIIT group compared to the traditional exercise or walking group. The movement of all measurement changes in both groups, which included decreases in body weight, %BF, FM and BMI, as well as an increase in FFM, are suggestive that the exercise interventions had an impact on anthropometric and body composition measurements. Such that the changes moved in a direction supportive of reduced adiposity with an increase in FFM, both of which are indicative of positive changes for improved health. The outcomes of this study provide a foundation for future comparisons of short-duration HIIT exercise and traditional exercise, or walking, on anthropometric and body composition measurement changes in sedentary, overweight, post-menopausal females over a 12-week period.
Footnotes
Acknowledgements
The authors thank Kathy Uhranowsky, CCRN, Marywood University, Scranton, PA, USA, for her data collection expertise. The authors would also like to thank Dr. Thomas Hogan, The University of Scranton, Scranton, PA for his statistical expertise.
Author Note
The supplementary material for this study was ‘The 10-Minute Trainer’. This DVD fitness program was used as the high-intensity interval training (HIIT). This DVD fitness program can be accessed and purchased via the Internet.
Contributorship
Joan A Cebrick Grossman, PhD, RD, the principal investigator is a contributor to this work. Ellen K Payne, PhD, ATC, served as co-investigator and is a contributor to this work, as she provided supportive material to the literature review and was involved with subject recruitment, data collection and manuscript editing.
Declaration of conflicting interests
The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.
Ethical approval
The Institutional Review Boards of The University of Scranton and Marywood University, Scranton, PA, USA, approved this study.
Funding
This work was supported by a cooperative grant #514587-7 from both The University of Scranton and Marywood University, Scranton, PA, USA, in the amount of $4038.
Guarantor
Joan A Cebrick Grossman, PhD, RD is the guarantor for this work, having had the original idea, completed the literature review, initiated data collection, completed all statistical analyses, interpreted the data and composed the manuscript.