Exercise as it relates to Disease/Is regular aerobic exercise alone effective for weight loss in sedentary adults?

This page is a analysis and critique of the journal article "A 6-Month Exercise Intervention Among Inactive and Overweight Favela-Residing Women in Brazil : The Caranguejo Exercise Trial" by Alves JG et al.

This was written as an assessment item for the unit Health, Disease and Exercise at the University of Canberra, 2021.

What is the background to this research?
Obesity and inactivity are major issues in the world right now. In 2005 Obesity cost Australia $21 billion. Obesity is a major contributing factor to other lifestyle diseases such as cardiovascular disease, type 2 diabetes, and obesity related cancers and increases the chance of death. The challenges that obesity places on society have meant that it has been a well-researched topic. Within the literature general exercise has a positive relationship with improvements in obesity and obesity related effects. This research wanted to examine the viability and efficacy of a known quantity of exercise in facilitating weight loss among previously sedentary or irregularly active overweight and obese adult women residing in poor living conditions.

Where is the research from?
The research conducted in Favela-residing Women in Caranguejo, Brazil. This part of Brazil has an extremely low socioeconomic status with an average daily income of $1 US dollar per day with a population of 3733. The research was published within the American public health associations journal and available in 2011.

What kind of research was this?
The research involved was a randomized control trial. Participants within the trial were assigned to either a control or intervention group.

What did the research involve?
The research involved the participants being split into either a control or intervention group. The intervention group completed an exercise protocol while the control group did nothing. The exercise protocol used was three, 50-minute exercises sessions a week for 6 months. These exercise sessions were aerobic in nature consisting of a 5-minute warmup followed by 40 minutes of moderate intensity exercise such as walking and rhymical movement to fast tempo music. This was followed by a 5-minute cooldown. During the most demanding portions of the exercise 40—60% of heart rate reserve was recorded using the Borg scale. All exercise was supervised by a trained physical education instructor. No dietary or other lifestyle modifications were made for the intervention group.

What were the basic results?
At the end of the 6-month intervention 96% of the participants successfully completed it. There was a statistically significant reduction in weight (Kg) with a mean of 1.69kg for the group. Body mass index score decreased from a mean of 29.8 to 29.2. With a final overall bodyweight change of 2%.

What conclusions can we take from this research?
This research helps quantify a specific amount of exercise that allows for weight loss in sedentary or irregularly active and weight/obese women in a poor area of developing countries. It also gives us insight into a hypothetical minimum effective dose and timeline for exercise without dietary modifications is necessary to facilitate weight loss reduction. It also helps us specify the type of exercise that can be effective in modality. The exercise used within this was not only aerobic in energy pathway nature but walking, dancing, or stepping in modality. This intervention unintentionally targeted women with a body mass index (BMI) of a score between 25 and 35 on average (29.7 +/- 3.313 which is categorised as class 1 obesity and the end of the overweight . This specific range of BMI targeted becomes a confounder when the potential efficacy of this intervention is considered to be used on other populations including other populations with BMI ranges that may be higher or lower in score then the range used. Weight loss is predominantly an energy expenditure vs energy intake equation . While this may be true in theory the practical application can be very challenging due to several different biopsychosocial factors. This study had a successful adherence and completion rate (96%) which may show the benefits on keeping intensity at a moderate level and keeping the modality simple to encourage individuals to be consistent with exercise and sustain it for a longer period of time. An important aspect to mention is that these results (amount of weight lost) while objectively low but statistically significant happened over the course of a 6-month period. This timeline may help practitioners appropriately educate the public, clients, and patients of realistic goals regarding the outcomes on weight loss and exercise without a change in diet or other lifestyle factors.

Practical advice:
This research helps use provide the following advice:


 * 1) ·        Regular exercise of at least 150 minutes a week at moderate intensity can promote weight loss.
 * 2) ·        Exercise choice can be as simple as walking, stepping, or dancing, require no equipment and does not need to be complex.
 * 3) ·        Moderate intensity may encourage better adherence for a longer period than high intensity exercise programs.
 * 4) ·        Dietary intervention alongside an  exercise regime like this would encourage further weight loss.
 * 5) ·        Exercising with supervision from a qualified professional and/or in a group setting may promote adherence to an exercise regime.
 * 6) ·        Expectations of the timeline that exercise effects weight loss could be re considered and become more conservative when realistically goal setting.

·

Further information/resources:
While this study predominantly focused on the effects that a specific quantifiable amount of exercise had on weight loss, there are other benefits of exercise on overweight/obese individuals besides just adipose tissue reduction. Other research completed has shown that a similar amount of exercise to this intervention (3x a week 30 minutes per session) with similar average % of weight loss (2.1%) improved both HDL cholesterol and insulin levels. Participants that completed exercise 3x a week for 30 minutes per session also had 8% increase in aerobic capacity. This intervention is similar to the one we reviewed and thus shows the other important outcomes that exercise has on people who are overweight/obese. It is still advised generally that weight loss between 5% and 10% is necessary to achieve a reduction of coronary heart disease risk factors.