Category Archives: Research Reviews

Second Life – Virtual Fitness Centres: What’s it all about?

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If you’re more concerned about getting involved with this virtual gym as quickly as possible, and don’t really care about this science stuff, then skip down to the third heading.

A Quick Outline

My avatar pumping iron.

My avatar, Jaye Jeffries, pumping iron.

A relatively recent news article in the science media highlights some of the discoveries of a longitudinal study conducted in the virtual environment Second Life, with the goal of delivering a weight loss and exercise program and comparing the differences between a face-to-face approach with a virtual online approach. After looking at the paper it appears promising, though there are certainly some questions that should be addressed about the methodology. First we’ll look at the research, then we’ll delve into an actual virtual gym in Second Life which is freely and publicly available to all.

Study Design Details

The study split 20 participants, 17 of which were female, into two groups, the face-to-face (FTF) group and the virtual group, and was conducted over a 9 month period with the first 3 months focussing on shorter-term weight loss and the following 6 months focussing on weight maintenance. Results showed that the FTF group had a greater degree of weight loss overall, though the virtual group had a greater degree of weight maintenance. With weight maintenance being an essential factor for long-term weight loss, that probably makes the virtual approach a little more superior even though the FTF group showed slightly higher degrees of weight loss.

Let me be honest here, while the study talks about “statistical significance” and differences between the two groups in this regard, there is also the concept of “clinical significance”, meaning that, in the real world – is there really enough of a difference to make it noticable and worthy of use as an intervention? In this regard we might consider the two groups identical in a clinically significant manner, and that’s a good thing! Perhaps the only drawback for this study is that the exercise intervention itself isn’t elaborated on, so I’m left to conclude that it wasn’t very thorough, but taking into account that the research focusses more on nutrition than exercise this can be overlooked with the expectation that future research will focus more on that aspect.

There were other benefits too for the virtual group over the FTF group, including signficantly greater fruit and vegetable consumption and higher levels of exercise (walking) as measured with a pedometer. Finally, to finish with the authors conclusions with which I completely agree:

“An adequately powered, longer-duration trial, with adequate assessment of potential mediators and moderators, is warranted to further evaluate the potential of Second Life as a delivery system for successful weight management.”

In my view, virtual and online environments continue to hold an untapped potential for helping to decrease barriers to exercise, and this study is the tip of the iceberg in many studies to follow that will help to unveil this hidden potential.

What’s all this about a gym in SL that you can access?

The most interesting part is that you can access Second Life fitness centres yourself, for free, where you can discuss exercise technique with real life professionals, get advice on nutrition and exercise programming, or just socialise and meet new people who are going through a similar experience. What makes this different to a real gym? There’s no cost, it’s far more accessible, and it acts as an introduction for people who might be too nervous or self-conscious to step foot into gym or fitness centre. I stress that there is a real need for translation of this platform into real life, which is what the discussed study begins to explore – the exposure and delivery of weight management techniques and how they translate into real life.

There are a number of Second Life fitness centres available, but my favourite by far – and which is actually funded by the United States Department of Agriculture (USDA) based on the above research study out of Kansas University, is the Avatar Fitness Club, hosted and run by the eXtension team. While there aren’t any events planned as yet, though promised to come, be sure to check it out and if you run into Thynka Little, DFox Spitteler, or even myself (Jaye Jeffries), be sure to say hi!

If you need more convincing, check out their Facebook page for more info.

Contemplating the potential for virtual exercise prescription.

Jaye Jeffries contemplating the potential for virtual exercise prescription.

(I’m a Second Life nerd from way back, so you’ll have to excuse the excitement from this post. The possibilities of combining two of my passions is an almost overwhelming possibility)

Have you visited the Avatar Fitness Club in Secondlife, and if so, what did you think? Share your thoughts in the comments!

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To Breakfast or Not To Breakfast?

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   Breakfast skipping, or intermittent fasting, has gained a lot of steam in the past year or two (“Big Breakfast Has Little Effect on Appetite“, “Extended Daily Fasting Overrides Harmful Effects of a High-Fat Diet“, “Skipping Breakfast Can Lead to Unhealthy Habits All Day Long“, “Could fasting be good for us?“, “Is breakfast making you fat?“, “The new appetite for fasting“). In fact I put the principle to use myself, and so thought this would be a great topic for my pathology research assignment. This report might be dry reading for those who aren’t used to reading scientific literature or associated nomenclature, so I’ll start by quoting the most relevant part of this report – the conclusion:

  “The key findings of this report are that breakfast appears to be clearly associated with weight gain in a dose-dependent relationship, though the direction of this relationship is not clearly established. Depending on the type of descriptive research method employed, different results are apparent, though the study by Schusdziarra et al. (2011) addressed some of these apparent contradictions.

   In conclusion, when interpreting the data in light of the contradictory nature of the research, there appears to be little evidence that breakfast skipping significantly contributes to overweight and obesity in adults, though individual factors such as age, obesity, exercise history, TDEE and TDEI should be taken into account and may in fact play a large role in the interpretation of the associations and correlations investigated in fasting and meal-skipping studies.”

   And there you have it, no real evidence for a causal relationship between breakfast skipping and weight gain, though the correlational data shouldn’t be dismissed out of hand and does provide us with some insight. Also, take into account that my critical analysis within this report only covers two pieces of primary literature, but that dozens of articles were accessed in the process. That said, I was forced to neglect the biochemical (grehlin, leptin, insulin, glucose, not to mention the interplay with lipid cells) physiological point of view somewhat in order to remain within the word limit for my report. If it’s the biochemistry of breakfast skipping that you’re after however, then I won’t reinvent the wheel – just head on over to Martin Berkhan’s blog “Leangains“, linked in the side panel, for more fasting biochemistry and references to primary literature than you can poke a stick at.

Without further delay, here’s the nuts and bolts!

(Feel free to comment at the bottom – what are your thoughts on breakfast consumption?)

Skipping breakfast: is it a significant contributor to overweight and obesity in adults?

Introduction

Overweight and obesity are growing health problems in Australia, with an increase from 57% of the population in 1995, to 61% in 2007-2008 (Health Risk Factors, 2012), having an enormous cost to the Australian government and society at an estimated $58 billion in 2008. Figure 1 shows data from the National Health Survey 2007-08, in which a larger proportion of overweight and obesity is prevalent amongst the aged adult population, particularly amongst males, with younger adults showing lower prevalence rates.

Figure 1: Proportion of Australian Adults Overweight or Obese (by age and sex). This figure illustrates increasing incidence of obesity with age (Health Risk Factors, 2012)

The importance of experimental investigation into the causal mechanisms of obesity becomes obvious in light of this data. This report sets out to examine associations between meal skipping (breakfast in particular), and overweight and obesity, and to challenge the long-held belief that breakfast is “the most important meal of the day” – a notion which has been picked up and discussed by the media in recent years (Roan, 2009) and mainstreamed by popular books such as Eat-Stop-Eat (Pilon, 2007).

This report will cover background information on obesity, including definitions, aetiology, pathogenesis, diagnosis and treatment. Two descriptive, observational studies will be analysed, summarised and critically evaluated in the context of other descriptive and experimental scientific research, and the strengths and weaknesses of each study and their separate contributions to this research question discussed. Finally, key-findings from the two studies will be restated and summarised.

Background Information

There are typically four different categories into which diseases may be placed; pathological, hereditary, physiological and deficiency disease. For the purposes of this report, obesity and overweight are considered from the context of their most prevalent cause, being physiological disease as a result of excessive nutrient intake and inadequate physical exercise (Obesity, 2012).

Bodyweight categories are grouped based on body mass index (BMI) measurements, with obese being in excess of 30kg/m2, overweight within the range of 25-29.9kg/m2, and a normal bodyweight falling in the range of 18.5-24.9kg/m2 (Overweight & Obesity, 2012).

Obesity is a chronic disease in which excessive amounts of adipose tissue are accumulated over time, leading to potential systemic issues and increased likelihood of comorbid disease (Weiss & Elixhauser, 2006). A caloric surplus is required over an extensive period of time for obesity to develop, usually necessitating low levels of exercise and a surplus in nutritional intake in order for total daily energy intake (TDEI) to exceed total daily energy expenditure (TDEE). Though this is the predominating cause of obesity, there are rare genetic disorders in which leptin insensitivity may cause obesity from childhood (Farooqi et al., 2007).

The pathogenesis of obesity is complex and only partially understood, though it’s clear that it depends on the function of several key metabolic hormones, including glucagon, insulin, leptin and ghrelin (Carlson et al., 2007), with adipose tissue itself also producing important mediators for the metabolism of triglycerides to adipose, including adiponectin, cytokines, chemokines and steroid hormones (Stanley L Robbins, 2012). Leptin is known to play a key role in the suppression of appetite (Duntas & Biondi, 2012), with decreasing levels of leptin being secreted when fat is lost from adipocytes – making long term weight loss more difficult. Insulin and glucagon control the transport of glucose into and out of the cells respectively, with long term blood-glucose levels and excessive lipid intake being tightly correlated with insulin resistance and type 2 diabetes (Fu, Gilbert, & Li, 2012). In addition, the risk of other comorbid diseases such as cardiovascular disease, gall bladder disease, osteoarthritis, bowel cancer and diabetes are increased in the presence of obesity (Schienkiewitz, Mensink, & Scheidt-Nave, 2012).

As obesity is defined as a BMI above 30kg/m2, diagnosis is simply made by utilising the formula BMI = weight/height2. The drawbacks of the simplicity of this formula lie in the fact that there is no distinction made between fat and muscle mess, therefore an incredibly muscular bodybuilder might be considered “obese” if only the BMI were used as a measurement. Obviously BMI needs to be utilised in the context of other available information to ensure the wrong demographic of “overweight” individuals are not captured and misclassified.

    Treatment for obesity typically lies in nutritional and exercise interventions, more specifically improving the quality of nutritional intake and decreasing the number of overall calories consumed along with implementation of an effective exercise program. Though this treatment is successful in a large number of obese subjects, particularly when delivered with cognitive behavioural therapy (Jakicic et al., 2012), those who suffer from hereditary causes and complications may require more medical intervention. Finally, some of the latest research by Mestdagh et al. (2012) involving intestinal bacteria and their role in the development of obesity opens interesting avenues for future exploration.

Annotated Bibliography & Critical Evaluation

Annotation 1

Huang, C. J., Hu, H. T., Fan, Y. C., Liao, Y. M., & Tsai, P. S. (2010). Associations of breakfast skipping with obesity and health-related quality of life: evidence from a national survey in Taiwan. International Journal of Obesity, 34(4), 720-725. doi: 10.1038/ijo.2009.285

This cross-sectional, descriptive study by Huang et al. used data from a National Health Interview survey in Taiwan which surveyed 15,340 individuals between the ages of 18 and 64. The study tested the association between breakfast skipping and obesity, as well as examining the possibility of a dose-dependent relationship between frequency of breakfast consumption and obesity.

The authors hypothesise that there exists an association between breakfast skipping and obesity, as well as a dose-dependent relationship in which an increased frequency of breakfast skipping is associated with an increased prevalence of obesity (amongst other behaviours deemed detrimental to health). The authors aimed to investigate these associations in adults as the majority of research conducted in this area in the past has focussed on a much younger demographic; primarily children and adolescents, making that research difficult to generalise to adults.

Although published in the International Journal of Obesity, the authors concede that the intended audience is specifically Taiwanese, and that the results are less applicable to other demographics, therefore these results are likely more relevant to Taiwanese health specialists and policy makers who are tasked with examination of potential causes and treatments for the growing obesity epidemic.

After careful analysis of the data, the authors conclude that breakfast skipping is associated with higher prevalence rates of obesity, in addition to being associated with other unhealthy behaviours such as smoking, alcohol consumption (though at what point this was considered detrimental to health was never addressed by the authors), and lack of exercise.

This study was chosen for analysis as it utilises a large segment of the adult population and is able to draw meaningful statistics due to this large sample size (n = 15,340).

Critical Evaluation

This study is relevant to this report as it directly investigates the association between frequency of breakfast skipping and prevalence of obesity, though there are advantages and disadvantages to their method of approach. One advantage is the fact that the authors utilised survey data, which allows a large breadth of information and amount of data to be acquired, however a major drawback of this approach is the inability to control confounding variables or tailor the data collected to include information such as macronutrient and micronutrient content and meal timing.

This study contributed to this report by confirming initial impressions that the majority of research is not applicable to the general adult population, as most studies examining the association between skipping breakfast (or fasting) and obesity are performed on a much younger demographic. This study also introduced the concept of a dose-dependent relationship, and more specifically that as breakfast-skipping increases so too does the prevalence of obesity. It also introduced the fact that breakfast skipping is associated with other unhealthy behaviours, including smoking, alcohol consumption, and lack of exercise. Finally, the associations found between breakfast skipping and lower scores of general health, vitality, mental health and social functioning helped to inform this report.

The authors addressed the research question by categorising the existing data into two groups: breakfast skippers and breakfast eaters (with breakfast skippers being those who ate breakfast once a week or not at all). The authors then analysed the percentage and P-value for each group, and subcategorised them into obese, smokers, alcohol drinkers, physically active, level of education, monthly income, marital status, and gender. The data was finally analysed using odds ratios.

This study gives direction for ongoing research into the links between breakfast dose (weekly frequency) and obesity, and helps to provide a basis for comparison of the results with other cross-sectional data as well as comparison with experimental, randomised controlled trials to compare and contrast the similarities and differences in outcomes.

Annotation 2

Schusdziarra, V., Hausmann, M., Wittke, C., Mittermeier, J., Kellner, M., Naumann, A., . . . Erdmann, J. (2011). Impact of breakfast on daily energy intake–an analysis of absolute versus relative breakfast calories. Nutr J, 10, 5. doi: 10.1186/1475-2891-10-5

This study sets out to investigate whether the reduction of caloric intake at breakfast can reduce the total daily caloric intake in a free-living and cross-sectional segment of the population, without compensatory eating behaviour. The study utilised 380 participants, 280 of which were obese and 100 of which were normal weight. Macronutrient and micronutrient intake were not analysed, though full nutrient details were gathered and recorded by each patient in the form of a food diary. This study focussed on the ratio of calories consumed at breakfast compared with those consumed throughout the entire day.

The authors introduce background information that shows seemingly contradictory studies and research around the effects of skipping breakfast or reducing caloric intake at breakfast and the prevalence of overweight and obesity. It’s proposed that these contradictory results between studies are a likely result of the different methodologies employed to manipulate the variables and analyse the data, particularly with regard to cross-sectional data vs. intraindividual analysis. The aim of this study was to compare two separate testing methodologies (cross-sectional data of a free living population and intraindividual analysis) on one data set and compare the results, helping to bridge the gap between studies utilising these separate methodologies.

This article was published in the Nutrition Journal, with the intended audience being those who are interested in nutritional research and have an understanding and appreciation of the application of the scientific process. This might include doctors, dieticians, exercise physiologists and other specialists with a nutritional interest, with repercussions for all segments of the healthy, overweight or obese populations.

The primary conclusion drawn by the authors is that a lower caloric intake at breakfast decreases the total daily caloric intake (with no compensatory eating behaviour), though this is put in the context of equivocal and at times contradictory research. This text was chosen for evaluation in part due to this balanced perspective of the available and contradictory studies, and the intent by the authors to resolve some of these differences.

Critical Evaluation

This study is relevant to this report as it puts into context the apparently conflicting research. It increases understanding by showing that a higher energy intake at breakfast is associated with an increased TDEI, but that this should be put into context of the energy expended during the day – particularly the amount of physical exercise engaged in. It also demonstrates the complexity of the issue and the difficulty of drawing clear conclusions on the issue of breakfast skipping or breakfast size and its association with overweight and obesity.

The authors address the research question by utilising patients from a hospital outpatient department, having them keep accurate logs of all food that was consumed and at what time of the day it was consumed. Both intra-individual data and ratio of daily energy intake were analysed from records taken over a two week period.

This study can be used for ongoing research into the differences in ratio between breakfast and total daily energy intake, and how this relates to obesity in studies that utilise different methodologies (preferably randomised controlled trials).

Conclusion

The key findings of this report are that breakfast appears to be clearly associated with weight gain in a dose-dependent relationship, though the direction of this relationship is not clearly established. Depending on the type of descriptive research method employed, different results are apparent, though the study by Schusdziarra et al. (2011) addressed some of these apparent contradictions.

In conclusion, when interpreting the data in light of the contradictory nature of the research, there appears to be little evidence that breakfast skipping significantly contributes to overweight and obesity in adults, though individual factors such as age, obesity, exercise history, TDEE and TDEI should be taken into account and may in fact play a large role in the interpretation of the associations and correlations investigated in fasting and meal-skipping studies.

 

References

Carlson, O., Martin, B., Stote, K. S., Golden, E., Maudsley, S., Najjar, S. S., . . . Mattson, M. P. (2007). Impact of reduced meal frequency without caloric restriction on glucose regulation in healthy, normal-weight middle-aged men and women. Metabolism, 56(12), 1729-1734. doi: 10.1016/j.metabol.2007.07.018

Duntas, L. H., & Biondi, B. Md. (2012). The interconnections between obesity, thyroid function, and autoimmunity: the multifold role of leptin. Thyroid. doi: 10.1089/thy.2011.0499

Farooqi, I. S., Wangensteen, T., Collins, S., Kimber, W., Matarese, G., Keogh, J. M., . . . O’Rahilly, S. (2007). Clinical and molecular genetic spectrum of congenital deficiency of the leptin receptor. N Engl J Med, 356(3), 237-247. doi: 10.1056/NEJMoa063988

Fu, Z., Gilbert, E. R., & Li, D. (2012). Regulation of Insulin Synthesis and Secretion and Pancreatic Beta-Cell Dysfunction in Diabetes. Curr Diabetes Rev.

Health Risk Factors. (2012). Australian Bureau of Statistics, Retrieved 16/09/12, from http://www.abs.gov.au/ausstats/abs@.nsf/Lookup/by%20Subject/1301.0~2012~Main%20Features~Health%20risk%20factors~233.

Jakicic, J. M., Tate, D. F., Lang, W., Davis, K. K., Polzien, K., Rickman, A. D., . . . Finkelstein, E. A. (2012). Effect of a stepped-care intervention approach on weight loss in adults: a randomized clinical trial. JAMA, 307(24), 2617-2626. doi: 10.1001/jama.2012.6866

Mestdagh, R., Dumas, M. E., Rezzi, S., Kochhar, S., Holmes, E., Claus, S. P., & Nicholson, J. K. (2012). Gut microbiota modulate the metabolism of brown adipose tissue in mice. J Proteome Res, 11(2), 620-630. doi: 10.1021/pr200938v

Obesity. (2012). Medline Plus, Retrieved 18/09/12, from http://www.nlm.nih.gov/medlineplus/obesity.html.

Overweight & Obesity. (2012). Centers for Disease Control and Prevention, Retrieved 16/09/12, from http://www.cdc.gov/obesity/adult/defining.html.

Pilon, Brad. (2007). Eat Stop Eat. Ontario, Canada: Strength Works Inc.

Roan, Shari. (2009). The new appetite for fasting, Sydney Morning Herald. Retrieved 25/08/12, from http://www.smh.com.au/lifestyle/diet-and-fitness/the-new-appetite-for-fasting-20090403-9muo.html

Schienkiewitz, A., Mensink, G. B., & Scheidt-Nave, C. (2012). Comorbidity of overweight and obesity in a nationally representative sample of German adults aged 18-79 years. BMC Public Health, 12(1), 658. doi: 10.1186/1471-2458-12-658

Schusdziarra, V., Hausmann, M., Wittke, C., Mittermeier, J., Kellner, M., Naumann, A., . . . Erdmann, J. (2011). Impact of breakfast on daily energy intake–an analysis of absolute versus relative breakfast calories. Nutr J, 10, 5. doi: 10.1186/1475-2891-10-5

Stanley L Robbins, Vinay Kumar, Ramzi S. Cotran (2012). Robbins Basic Pathology (NINTH EDITION ed.).

Weiss, A. J., & Elixhauser, A. (2006). Obesity-Related Hospitalizations, 2004 versus 2009: Statistical Brief #137 Healthcare Cost and Utilization Project (HCUP) Statistical Briefs. Rockville MD.

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Microwave Cooking and Nutrient Breakdown

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We’re almost 3 weeks into the new year, and many have started with a list of new years resolutions, and perhaps even thrown a few of those resolutions out the window. For many these included eating healthier (particularly more vegetables & fruit) and an exercise program. They’re all very formidable goals, made even more difficult when the aspiring healthy consumer is tasked with separating reality from nonsense in their pursuit of what works, what doesn’t, and what is rooted in solid reality-based principles.I don’t want to carry on too long with this intro, so let’s skip right to the crux of the matter; Microwaving vegetables, should you do it? And does it denature the nutrients? There’s a popular belief which has been around for quite some time that microwaving vegetables (and meat, carbohydrates, or any other nutritional victim bound for the microwave) decreases the nutritional value of the food by altering the molecular structure of the macro or micronutrients.Nonsense. In fact, the very opposite is the case for a number of important nutrients.

Dispelling nonsense makes Mr Broccoli very happy.

Microwaving Vs Stove Top Cooking

Of course microwaving your food affects the molecular structure, this is what we call “cooking”. There have been plenty of studies investigating the effects of microwaving vs stove cooking vegetables and other food, for example here, here1, and here2. These studies show that microwaving vegetables or other foods is superior when considering nutrient preservation (at least, for those nutrients being studied) when compared to traditional stove-top cooking.

There’s some history behind the ‘Microwave Militia’ as they have been dubbed by the more skeptical community, however I won’t expound upon them here. In addition, I recommend listening to (or reading the transcript) of Brian Dunning’s “Skeptoid” podcast episode which was entirely devoted to this issue, though his focuss isn’t specifically on nutrient preservation but rather unsupported claims of negative health effects when microwaving food and beverages.

Go Ahead, Microwave Your Veggies!

Getting enough vegetables and good nutrition is hard enough without being fed misinformation from those who stubbornly oppose evidence based research, particularly those who ought to know better. So throw those veggies into your microwave and be happy in the knowledge that you’re not only saving time and effort, but also increasing your nutrient intake and increasing the likelihood of sticking to a healthier diet.

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References

      1.   Effect of microwave cooking or broiling on selected nutrient contents, fatty acid patterns and true retention values in separable lean from lamb rib-loins, with emphasis on conjugated linoleic acid

Abstract

Proximate composition and fatty acid profiles, conjugated linoleic acid (CLA) isomers included, were determined in separable lean of raw and cooked lamb rib-loins with their subcutaneous and intermuscular fat, prepared as roasts or steaks. Two combinations “cooking method × type of cut” were selected: one is a traditional method for this meat (broiling of steaks), while the other (microwaving followed by final grilling of roasts) is far less widely used. The two methods, similar as regards the short preparation time involved, were also evaluated for cooking yields and true nutrient retention values. The cooking yield in microwaving was markedly higher than in broiling. Significant differences between the two methods were also found in the true retention values of moisture, protein and several fatty acids, again to the advantage of microwaving. On the basis of the retention values obtained, with microwaving there was a minimum migration of lipids into the separable lean, consisting almost exclusively of saturated and monounsaturated fatty acids, while there were small losses of lipids in broiling, almost equally divided between saturated, monounsaturated and ω6 polyunsaturated fatty acids. On the whole, the response to cooking of the class of CLA isomers (including the nutritionally most important isomer cis-9,trans-11) was more similar to that of the monounsaturated than the polyunsaturated fatty acids.

2. Sensory attributes and nutrient retentionin selected vegetables prepared by conventional and microwave methods

Abstract

Sensory characteristics and retention of vitamin C, vitamin B6, calcium, and magnesium were determined in vegetables cooked by conventional and microwave methods. Fresh broccoli, cauliflower, and potatoes and frozen corn and peas were cooked by boiling, steaming, microwave boiling and microwave steaming to equivalent tenderness as measured by a shear press. The sensory analysis of the vegetables cooked by the four methods indicated that some differences existed in color, flavor, texture, and moistness of the vegetables. No one method resulted in vegetables with optimum sensory characteristics. The nutrient retention was highest in foods cooked by microwave steaming, followed by microwave boiling, followed by steaming, and then by boiling. Generally vegetables cooked by microwave techniques retained higher percentages of the U. S. Recommended Daily Allowances for the nutrients than those cooked by conventional methods.

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Stretching Before Exercise: Good or Bad?

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My research assignment for my diploma, examining the benefits and drawbacks of stretching before and after exercise, as well as comparing the different stretching methodologies.

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Stretching Before Exercise: Good or Bad?
by Jason Jarred

TABLE OF CONTENTS

Precis

Introduction

Discussion
1.0 Attitudes Toward Stretching
2.0 The Unstated Correlation
3.0 Pre Exercise Warm-up
4.0 Types of Stretching
4.1 Static
4.2 Dynamic
4.3 Ballistic
4.4 Proprioceptive Neuromuscular Facilitation
5.0 Range of Motion (ROM) & Flexibility
6.0 Delayed Onset Muscular Soreness (DOMS)
7.0 Injury Prevention

Conclusion

References

Appendices
Appendix A: Further Research Material 13
Appendix B: Definitions 14
Appendix C: Research Chart 15

Precis
This report aims to research the most common modalities of stretching, and their effect on performance factors, injury prevention, and delayed onset muscular soreness (DOMS).
This research was performed online, with articles retrieved from a large variety of sports, medical, and rehabilitative journals (via PubMed), and a host of other peer reviewed, scientifically recognized and freely available material. Searches were performed using keywords relevant to the topic and abstracts used as source material to inform the large majority of the content within this report. Some modalities of stretching, such as static, had a large variety of material available due to more prevalent use amongst the population, and the number of years established as a pre-exercise preparation technique. It should be noted that each scientific study investigated different aspects of post stretching outcomes, utilised different demographics, study protocols, aims, hypothesis, and in some instances used different types of equipment to verify muscle/joint tension or effect on performance factors.
Within the following discussion, the complexities of the stretching debate will be revealed. Overall, it was discovered that most modalities of stretching improved flexibility, however some modalities also have a negative impact on performance factors if carried out prior to exercise or sport.

Introduction
Research on this topic is necessary to help inform both amateurs and professionals who utilise stretching as a part of their exercise program and may find this information useful for consideration of altering current pre or post exercise activities.
Initially this report sets out current attitudes toward stretching, followed by supporting evidence for warm-up up prior to exercise. Following this, different stretching modalities will be briefly analysed and compared, and the effects on various performance factors taken into consideration. This report does not cover the effects of rehabilitative stretching or physiotherapeutical approaches to acute or chronic injuries associated with sport or exercise, but rather will focus on stretching as a means of injury and soreness prevention and the effects of stretching on performance factors.
The research for this report is conducted by Jason Jarred, for Jane Madison, as part of the required curricula for Fitness Speciality (Stage 2), Research Projects, Randwick College.

Discussion
1.0 Attitudes toward Stretching
To ascertain general attitudes toward stretching efficacy a search was performed for the most easily accessible online discussions (‘stretching’ and ‘forum’) using Google. Amongst a host of varying professional and amateur opinions, experienced personal trainers continually support stretching from a position of experience and anecdote1. Many discussion participants neglect to take into account the clinical and scientific research when formulating opinions, and allow anecdotes to act in place of scientific evidence. Fitness professionals have a duty of care for their clients, to both protect them from harm and dispense accurate information. A higher level of scientific appreciation and critical thinking encouraged during collegiate education may be helpful in order to meet these responsibilities and to properly fulfill the duty of care.

While there is plenty of information available via sources such as YouTube, fitness/bodybuilding forums, and Google searches, there also appears plenty of misleading and partial information on the pros and cons of stretching and why it is considered to be an important part of an exercise program.
The two top results for YouTube were both quite informative videos. The first clip demonstrates a basic static stretching routine for the whole body5, while guiding the viewer on static stretching methodology. The second video presents some detail on PNF stretching24 and is more comprehensive than the first clip. In neither of these videos are the following points discussed: the science, evidence, desired objective, why it should be performed, or when it should be performed. With that said, some admission of uncertainty around efficacy was provided by the first clip, that stretching may “help increase flexibility and ‘perhaps’ prevent injury”.
After assessment of the above sources, attitudes toward stretching appear to remain, for the most part, unchanged amongst some amateur exercise enthusiast and professionals. With these factors in mind we now turn toward the reasoning and logic behind the implementation of a stretching program.

2.0 The Unstated Correlation
The argument for stretching hinges on an unstated correlation; warm-up prepares the muscles for stretching, stretching increases flexibility, flexibility improves ROM (Range of Motion), ROM helps prevent injury and muscular soreness. This is a multi-claim assumption, each stage of which needs to be analysed to ascertain the evidence supporting and negating each link of the chain. Should even a single link be supported by doubtful or lacking evidence, it serves to further call into question the efficacy of stretching and its relationship with muscular soreness and injury.

3.0 Pre-exercise Warm-up
Pre exercise warm-up should be analysed prior to analysis of the benefits or deficits of stretching. It has been found that warm-up and static stretching both, individually, significantly increase flexibility of muscle prior to exercise17.
In addition, warm-up prior to exercise helps to decrease risk of injury by increasing elasticity of the muscle21. The referenced studies appear to support the common knowledge that warm-up prior to exercise is beneficial to flexibility, particularly if it is specific to the activity being engaged in.

4.0 Types of Stretching
Several types of stretches were taken into consideration: static, dynamic, ballistic, and proprioceptive neuromuscular facilitation (PNF). Of these stretches, the most scientifically researched appears to be static, while the least researched is ballistic. Of particular interest is static stretching due to widespread use and its acceptance as a pre exercise warm-up or post exercise cool-down.
Most scientific studies focus on a single one or two of these stretching modalities, and the factors measured are often a mixture of several of the following; anaerobic capacity, agility, strength, speed, power, endurance, soreness prevention, ROM and flexibility.
Definitions for factors measured and what defines a particular type of stretch is considered important, especially in light of contradictions and differences in previous research being possibly due to conflicting definitions of ‘warm-up’ and ‘stretching’30. A list of the definitions used for each stretch modality discussed herein is therefore included in Appendix B for reference. With semantic definitions, types of stretches and performance factors taken into consideration, the different stretching modalities will now be analysed in brief and cross referenced with available research.

4.1 Static Stretching
Of the stretching modalities that exist, the most well studied, discussed and utilised appears to be static stretching. Several studies are suggestive of a positive correlation between static stretching and improved flexibility and range of motion (32, 6, 25, 17, 31). In one study, there appears a negative correlation between static stretching and ‘power’22, while three more studies suggest no positive or negative correlation (no effect) between static stretching and the following performance factors: anaerobic capacity, agility, endurance, soreness prevention10, strength, speed32, and range of motion6. Static stretching appears to have varying degrees of effects depending on the exercise participated in, suggesting its use may not be recommended prior to consideration of performance factors.

4.2 Dynamic Stretching
Overall, dynamic stretching comes out quite favorably. Several studies identify positive outcomes between dynamic stretching and the following performance factors: anaerobic capacity, agility, strength, endurance10 and power7,12. Other studies which support dynamic stretching (see Jamtvedt et al 2009) appear to have been embraced by some corners of the media as a replacement for static stretching altogether19. While dynamic has certainly been demonstrated to have some superior outcomes over static, the implication that it should altogether replace static is questionable, particularly when taking into consideration the contradictory results of dynamic stretching on flexibility17.
Again, here we see a modality of stretching whose use should perhaps not be recommended prior to consideration of performance factors, and exercise to be engaged in.

4.3 Ballistic Stretching
Ballistic is generally viewed as a damaging practice if not performed correctly. In one study by Covert et al 2010, the results were surprising given the general consensus. No injuries or complications were associated with static or ballistic, however a greater increase in flexibility was correlated with static over ballistic. This calls into question the validity of using ballistic to increase flexibility, particularly in light of the possible detrimental effect on ‘power’ after ballistic is performed22.

4.4 Proprioceptive Neuromuscular Facilitation (PNF)
PNF is often hailed as the most effective technique for improving ROM and flexibility, with plenty of scientific support for these claims11, 6, 15, 2, 20. In addition, an improvement in running mechanics may result when PNF is performed post-exercise on a regular basis2.
PNF may take the form of passive and active. Active utilises a thera-band or another persons assistance, passive is simply performed against gravity. A third category of PNF exists, known as contract relax (CR)PNF16, which is a modification of the original PNF technique.
Knowledge of the existence of these subcategories is important, as many scientific studies appear not to clarify which type of PNF was tested, and those that do make the distinction have discovered considerable differences between the subcategories of PNF stretching. For example, one PNF stretching study6 correlates PNF active with greater results in knee ROM than does PNF passive.
An interesting discovery from several studies is that increase in ROM and flexibility was not due to lengthening of muscle fibers or joint tendons, rather perception of stretch tolerance in the individual15,26, 16 – a factor possibly dependent on psychological and physiological factors beyond simple muscular tension.

5.0 Range of Motion (ROM) & Flexibility
Stretching improves acute and chronic flexibility and ROM8, though some modalities are more effective at increasing flexibility/ROM than are others6. In addition, depending on the activity participated in post warm-up and type of stretching modality used, either a negative or positive effect on performance factors may result in addition to effects on flexibility and ROM.
There is a difficulty when analyzing available research in that different terminology is used from study to study, and not clearly defined. The following terms are used frequently during scientific abstracts and related resources, and are necessarily equated with flexibility: tension, compliance, stiffness, length, elasticity, stretch tolerance, and ROM. This takes into account three primary factors:
1) that some studies make these equivocations themselves,
2) that within some studies, there were clear distinctions made between some of these (for example, tolerance Vs flexibility), and
3) without definitions provided within the studies themselves, it would be difficult to determine otherwise.

The evidence seems conclusive in regard to stretching improving flexibility/ROM6, 31, 32, however the link between flexibility/ROM and injury prevention and muscular soreness prevention now needs to be established.

6.0 Delayed Onset Muscular Soreness (DOMS)
Delayed onset muscular soreness (DOMS) is often given as a reason to incorporate a stretching routine into the exercise program, either before or after exercise. Both pre-exercise and post-exercise stretching do not significantly decrease muscular soreness after exercise27, 9, 13, 4, however pre-exercise stretching may reduce sensations of ‘perceived’ soreness and stiffness after exercise18.
There are three important factors to take into account with the latter referenced study however,
1) There was no control group,
2) the study was not blinded, and
3) the use of the terminology ‘perceived soreness’ within the abstract raises the question of placebo effect and how this may have been influenced by lack of blinding protocols.

While these studies appear contradictory, and given the weaknesses in the above study, it seems reasonable to conclude that stretching does not have a significant effect on DOMS, particularly when taking into account that both static and ballistic stretching may actually increase DOMS28, rather than prevent it.

7.0 Injury Prevention
Perhaps the most important benefit claimed is the potential to decrease risk of injury. Shoulder injury has been associated with a limited range of motion in baseball players23, however some research suggests that stretching before or after exercise does not significantly decrease risk of injury13, although it may decrease ‘bothersome soreness’.
ROM may be specific to the sport in question, and an excess of flexibility in one sport may measure up as an inadequate amount of flexibility in another. Stretching may play a role in injury prevention, taking into consideration three important factors:
1) exercise/sport to be participated in,
2) current ROM of relevant joints, and
3) stretching modality utilised and effect on both ROM and exercise specific performance factors.

It should also be noted that while some research suggests no significant correlation between stretching and ‘all-injury’ prevention, there were correlations between stretching, reduction of musculotendinous injuries, and ‘bothersome soreness’27, suggesting that stretching does effect perception of bodily soreness.

Conclusions
There exist several stretching modalities as discussed in this report, and within each there are variations upon variations. Performance factors for the exercise to be participated in should be taken into consideration in the first instance, and a stretching modality selected based on the effect revealed within scientific literature. For amateurs engaging in exercise, the best course of action seems to be abstaining from stretching prior to exercise, but engaging in static, dynamic or PNF stretching post exercise (or on non exercise days) on a semi regular basis. The potential for over-flexibility to in fact increase the risk of injury should be taken into account, and the stretching modality applied in a thoughtful manner.

See Table 1 for a summary of stretching modalities Vs performance factors.

References
1. American Council on Exercise, Flexibility & Stretching, Accessed 5 May 2010, <http:>

2. Caplan N, Rogers R, Parr MK, Hayes PR 2009, The effect of Proprioceptive neuromuscular facilitation and static stretch training on running mechanics, J Strength Cond Res, PubMed PMID: 19528850, accessed 7 May 2010, <http:>

3. Covert CA, Alexander MP, Petronis JJ, Davis DS 2010, Comparison of Ballistic and Static Stretching on Hamstring Muscle Length using an Equal Stretching Dose, J Strength Cond Res, PubMed PMID: 20375742, accessed 6 May 2010, <http:>

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5. Diethealth, 2008, Free Flexibility Video: 5-Minutes Stretch Routine, YouTube, Accessed 30 April 2010, <http:>

6. Fasen JM, O’Connor AM, Schwartz SL, Watson JO, Plastaras CT, Garvan CW, Bulcao C, Johnson SC, Akuthota V 2009. A randomized controlled trial of hamstring stretching: comparison of four techniques, J Strength Cond Res, PubMed PMID: 19204565, accessed 30 April 2010, <http:>

7. Gelen E 2010, Acute effects of different warm-up methods on sprint, slalom dribbling, and penalty kick performance in soccer players, J Strength Cond Res, PubMed PMID: 2030033, accessed 6 May 2010, <http:>

8. Gleim GW, McHugh MP 1997, Flexibility and its effects on sports injury and performance, Sports Med, PubMed PMID: 9368275, accessed 4 May 2010, <http:>

9. Herbert RD, de Noronha M 2007., Stretching to prevent or reduce muscle soreness after exercise, Cochrane Database of Systematic Reviews 2007, Issue 4. Art. No.: CD004577, accessed 29 April 2010, <http:>

10. Herman SL, Smith DT 2008, Four-week dynamic stretching warm-up intervention elicits longer-term performance benefits, J Strength Cond Res, PubMed PMID: 18545176, accessed 1 May 2010, <http:>

11. Higgs F, Winter SL 2010, The effect of a four-week Proprioceptive neuromuscular facilitation stretching program on a isokinetic torque production, J Strength Cond Res, PubMed PMID: 19620921, accessed 7 May 2010, <http:>

12. Jaggers JR, Swank AM, Frost KL, Lee CD 2008, The acute effects of dynamic and
ballistic stretching on vertical jump height, force, and power, J Strength Cond
Res, PubMed PMID: 18841078, accessed 30 April 2010, < <http:>

13. Jamtvedt G, Herbert RD, Flottorp S, Odgaard-Jensen J, Havelsrud K, barratt A, Mathieu E, Burls A, Oxman AD 2009, A pragmatic randomized trial of stretching before and after physical activity to prevent injury and soreness, Br J Sports Med, PubMed PMID: 19525241, accessed 9 May 2010,

15. Mahieu NN, Cools A, De Wilde B, Boon M, Witvrouw E 2009, Effect of Proprioceptive neuromuscular facilitation stretching on the plantar flexor muscle-tendon tissue properties, Scand J Med Sci Sports, PubMed PMID: 18627559, accessed 7 May 2010, <http:>

16. Mitchell UH, Myrer JW, Hopkins JT, Hunter I, Feland JB, Hilton SC 2007, Acute stretch perception alteration contributes to the success of the PNF “contract-relax” stretch, J Sport Rehabil, PubMed PMID: 17918696, accessed 7 May 2010, <http:>

17. O’Sullivan K, Murray E, Sainsbury D 2009, The effect of warm-up, static stretching and dynamic stretching on hamstring flexibility in previously injured subjects, BMC Musculoskelet Disord, PubMed PMID: 19371432, accessed 4 May 2010, < <http:>

18. Reisman S, Walsh LD, Proske U 2005, Warm-up stretches reduce sensations of stiffness and soreness after eccentric exercise, Med Sci Sports Exerc, PubMed PMID: 15947716, accessed 9 May 2010, <http:>

19. Reynolds G 2008, Stretching: The Truth, New York Times, accessed 29 April 2010, <http:>

20. Marchese R, Hill A, 2005, The Essential Guide to Fitness, 1st Edition, Prentice Hall, Frenchs Forest NSW.

21. Safran MR, Garrett WE Jr, Seaber AV, Glisson RR, Ribbeck BM 1988, The role of warmup in muscular injury prevention, Am J Sports Med, PubMed PMID: 3377095, accessed 4 May 2010, <http:>

22. Samuel MN, Holcomb WR, Guadagnoli MA, Rubley MD, Wallmann H 2008. Acute effects of static and ballistic stretching on measures of strength and power, J Strength Cond Res, PubMed PMID: 18714248, accessed 30 April 2010, <http:>

23. Scher S, Anderson K, Weber N, Bajorek J, Rand K, Bey MJ 2010, Associations among hip and shoulder range of motion and shoulder injury in professional baseball players, J Athl Train, PubMed PMID: 20210623, accessed 4 May 2010, < <http:>

24. Scott D 2007, Top 6 Stretching Exercises, YouTube, accessed 30 April 2010, < <http:>

25. Shadmehr A, Hadian MR, Naiemi SS, Jalaie S 2009, Hamstring flexibility in young women following passive stretch and muscle energy technique, J Back Muscoloskelet Rehabil, PubMed PMID: 20023343, accessed 4 May 2010, <http:>

26. Sharman MJ, Cresswell AG, Riek S 2006, Proprioceptive neuromuscular facilitation stretching: mechanisms and clinical implications, Sports Med, PubMed PMID: 17052131, accessed 7 May 2010, <http:>

27. Small K, McNaughton L, Matthews M 2008, A systematic review into the efficacy of static stretching as part of a warm-up for the prevention of exercise-related injury, Res Sports Med, PubMed PMID: 18785063, accessed 29 April 2010, <http:>

28. Smith LL, Brunetz MH, Chenier TC, McCammon MR, Houmard JA, Franklin ME, Israel RG 1993, The effects of static and ballistic stretching on delayed onset muscle soreness and creatine kinase, Res Q Exerc Sport, PubMed PMID: 8451526, accessed 9 May 2010, <http:>

30. Woods K, Bishop P, Jones E 2007, Warm-up and stretching in the prevention of muscular injury, Sports Med, PubMed PMID: 18027995, accessed 29 April 2010, <http:>

31. Wyon M, Felton L, Galloway S 2009, A comparison of two stretching modalities on lower-limb range of motion measurements in recreational dancers, J Strength Cond Res, PubMed PMID: 19855344, accessed 4 May 2010, <http:>

32. Ylinen J, Kankainen T, Kautiainen H, Rezasoltani A, Kuukkanen T, Hakkinen A 2009, Effect of stretching on hamstring muscle compliance, J Rehabil Med, PubMed PMID: 19197574, accessed 30 April 2010, < <http:>Appendix A
Further Research Material Accessed

Compliance, Accessed 1 May 2010, <http:>

David B, Michel C, Michael S, Alf B. Neurodynamics/Neuro Mobilisation, Accessed 1 May 2010, <http:>

Fletcher IM, Anness R 2007, The acute effects of combined static and dynamic stretch protocols on fifty-meter sprint performance in track-and-field athletes, J Strength Cond Res, PubMed PMID: 17685686, accessed 9 May 2010, <http:>

Lew PC, Briggs CA 2010, Relationship between the cervical component of the slump test and change in hamstring muscle tension, Man Ther, PubMed PMID: 11485360, accessed 1 May 2010, < <http:>

Swan N 2009, Stretching before exercise: do you need to?, ABC Health & Wellbeing, accessed 4 May 2010, <http:>

Wikipedia, Active Stretching, Accessed 29 April 210, <http:>

Wikipedia, Passive Stretching, Accessed 29 April 2010, <http:>

Wikipedia, PNF Stretching, Accessed 29 April 2010, <http:>

Wikipedia, Resistance Stretching, Accessed 29 April 2010, <http:>Appendix B

Definitions Used
Active: Range of motion is increased through voluntary contraction.
All-injury: All injuries associated with sporting (excluding musculotendinous injuries).
Ballistic: Bouncing beyond the usual ROM.
Bothersome soreness: Soreness not associated with specific injuries or illness
Dynamic: Performed whilst moving. The ROM is not exceeded (as in static stretching).
Muscle compliance: Release of tension and increased flexibility1
Passive: range of motion is increased through external assistance.
PNF: A mix of contracting the muscle, relaxing the muscle, and moving further into the stretch as the muscle relaxes.
Static: Pushing to the limit of ROM and holding

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