Alrighty then, I am a bit behind in posting these, so here are the summaries from June and July, courtesy of Exercise ETC. Some good stuff - especially the research on skill learning and plyometrics.
FitBits Exercise ETC's Review of Exercise Related Research Compiled by Chris Marino, MS, CSCS Director of Education, Exercise ETC
June, 2010 FitBits FDA Issues Warning for Popular Weight Loss Drug Orlistat is a popular weight loss drug originally sold by prescription only, (under the brand name Xenical) which recently became available OTC as Alli in a lower dose. Orlistat works by blocking the absorption of fat during digestion, thus reducing the total calories assimilated by the body. Although the drug is effective, studies report that weight loss from the addition of Orlistat to a program that includes diet and exercise is modest; up to 6.6 lbs. additional over 6 months. Just last month the FDA issued a warning to Orlistat users following the review of 12 cases of liver failure in which the patients were documented to have been using one of these products. Because there are additional variables involved, including other medications, the FDA claims that a direct link is not possible. Regardless, the maker of Xenical/Alli, Glaxo-Smith-Kline is now required to add the potential for liver failure to the product label. To ensure the safety of your clients, the FDA urges anyone who experiences symptoms while using Orlistat to see their physician immediately, and to file a report with the FDA. Symptoms include but are not limited to nausea, diarrhea, loss of appetite or fatigue. Liver failure progresses quickly, within 48 hours. Immediate medical attention should be sought if symptoms present. FDA Consumer Update. May 2010. Weight Loss Drugs and Risk for Liver Failure._____Works Best for Increasing Flexibility: Stretching or Weight Training? The ongoing discussion over the benefits of stretching, or lack thereof has arguably led to more confusion amongst fitness professionals than any other major topic. Should you stretch at all? If yes, when should you stretch? How long should you stretch? What type of stretching is best? These are all questions that, depending on which expert you ask or research you uncover you’re bound to get a different answer. Unfortunately, this next study is not going to clarify the issue. However, it might present an opportunity to look at stretching in a different light. In a study presented at the national convention of the American College of Sports Medicine, it was reported that resistance training offered the same benefits to flexibility as a static stretching. Researchers assessed the hamstring and shoulder flexibility of thirty-seven volunteers along with a strength measure for both quadriceps and hamstrings. Twelve of the subjects served as controls, while twenty-five were randomly selected for either a resistance training or flexibility training program. After 5 weeks of training or stretching, improvements to flexibility were similar for both test groups. Moreover, the resistance-training group increased strength in addition to flexibility. The study is of interest to fitness professionals not because it indicates limited value to stretching while performing a resistance-training program. Instead, it should be looked at in regards to efficiency. In the age of twice weekly 45-minute training sessions there is little time to spend on activities with limited return. Thus, for the beginner looking to build muscle and lose fat it may be more beneficial to ignore stretching in favor of resistance training. The bulk of the research continues to suggest a strong value for a variety of stretching forms. At this point it is up to the fitness professional to determine best practice on an individual basis. Press Release. American College of Sports Medicine. National Convention. June 4, 2010._____Stability Ball Enhances Lumbar Stabilization Training The use of unstable surface training (UST) has come under fire in recent years. Whether misunderstood or misused, there is definitely a need for additional study on UST to determine the best applications in fitness environments. In a recent study, researchers tested the difference in muscle activation during trunk or core exercise both on stable and unstable surfaces. Researchers used surface EMG to measure muscle recruitment patterns during five traditional lumbar stabilization exercises in 9 subjects. The peak recruitment of 5 core muscles was recorded: rectus abdominus, lumbar multifidus, erector spinae, transverse abdominus, and external oblique. Participants performed the plank, curl-up, side plank, back bridge and birddog on both stable surface and an unstable surface (i.e. stability ball, disc, etc). The plank increased muscle activity in all muscles when on the unstable surface. When using the unstable surface the quadruped birddog, and side plank, however, saw only increases in superficial muscle activity, and not deep core (i.e. transverse abdominus and multifidus). Interestingly, when the curl-up was performed on a Stability Ball the recruitment of the transverse abdominus decreased, while the external obliques increased. Unfortunately, the data from this study indicates that the back bridge did not benefit from incorporating the unstable surface. Although the jury remains "out" on standing UST and performance, there appears to be a useful application for prone and side stabilizing activities. Moreover, as “core neutral” training becomes the dominant form of abdominal strengthening industry-wide, we need to explore ways to increase muscle activity and tension during such exercises for progression. Studies such as this are a step in that direction. Imai, A. et al (2010) Trunk Muscle Activity During Lumbar Stabilization Exercises on Both a Stable and Unstable Surface. J Orthop Sports Phys Therapy. 40(6):369-375.______Excess Abdominal Fat Associated with Smaller Brains The brains of obese individuals may be shrinking. According to a recent study completed at Boston University Medical Center the brain volume of overweight and obese individuals is significantly less than that of their normal weight counterparts. Researchers tested over 700 individuals who were previously enrolled in the Framingham Offspring Cohort. Visceral and subcutaneous body fat was assessed via abdominal CT scan, while brain volume was measured using MRI. Total brain volume was then compared to the above body composition factors, in addition to Body Mass Index (BMI) and waist circumference. Interestingly the data indicated an inverse relationship between body fat and brain size. The most significant link was between visceral body fat and total brain volume. Simply, the higher the fat the smaller the brain. Scientists are expecting to explore the underlying mechanisms and speculate hormones such as adiponectin, leptin, resistin or ghrelin may be responsible in part for the brain atrophy noted. Why is this study important? Researchers have previously uncovered links between obesity and a greater risk for early onset of Alzheimer’s Disease and/or dementia. Until now, the underlying mechanisms behind such a relationship were only speculative. Although there is limited evidence to indicate cognitive impairment resulting from brain shrinkage, scientists hope to find a link that will allow them to understand the obesity-disease relationship. Press Release: Study Finds Fat Around the Abdomen Associated with Smaller, Older Brains in middle-aged Adults. Boston Medical Center. May 24, 2010.* * * * * * * * * * * * * * *July, 2010 FitBits New Heart Rate Formula May Improve Program Design for Women The use of heart rate to predict and monitor exercise intensity is common amongst exercisers of all types, from endurance athletes to cardiac rehab participants. Although heart rate remains the best option available for gauging intensity there remain questions regarding the validity of the many equations available to predict target heart rate for training. The maximum heart rate (HRmax) formula that currently serves as the foundation for prescribing intensity is 220 minus age. Two studies over the past decade address both gender and age-related drawbacks to this formula. First, approximately 8 years ago, researchers at the University of Colorado reported that the HRmax formula was not valid for individuals over 40. They determined that the predicted decline in HRmax that occurs with age is considerably slower after the age of 40 than before. Hence, they developed the following formula which is believed to offer a more accurate prescription for an older population: 208 – (Age x .7). This past month it was reported that the traditional HRmax formula results in an inflated exercise heart rate for women. In this study of over 5,400 women, participants completed a maximal treadmill test after which they were followed for a period of 16 years. The data collected from the project determined an association between risk for heart attack and abnormal heart rate readings during the previous treadmill test. Moreover, it resulted in a new formula to calculate maximum heart rate in women:206 – (Age x .88)Researchers determined that women who were programmed based on the original max HR formula were unable to sustain predictably manageable intensities (i.e. 65-85% max HR). The new formula predicts a lower max HR and thus lower relative HR’s for women. This study presents an interesting challenge to fitness professionals. Although it is acceptable, should you choose to incorporate the new formula, which results in a lower relative intensity, do the client's results suffer? If so, it may be more appropriate to first use the newer formulas, continue to incorporate HR monitoring, but to include perceived exertion to modify intensity on an individual basis. Tara Parker-Pope. Recalibrated Formula Eases Women’s Workouts. NY Times Health Update. July 5, 2010._____Is BMI Obsolete? The Body Mass Index (BMI) is a value placed on the relationship between an individual’s height and weight. BMI value is based on a simple paradigm with respect to health and risk for disease. If there are two individuals of equal height and one individual is significantly heavier, the BMI will indicate a greater risk for poor health for the heavier person. From its inception the Body Mass Index has been questioned in its ability to accurately predict health risks and estimate body fat. The BMI has numerous flaws. For one, it fails to account for the lean body mass and fat mass ratios in assessing healthy weight. The upside to BMI, however, and the primary reason why it remains a mainstream tool for healthcare professionals has everything to do with its simplicity in comparison to other measurements such as body fat testing, or anthropometrics. There may be a new option on the horizon. In a study recently published in the journal Pediatrics, researchers from the University of Michigan determined that a child’s neck circumference was equally effective as a predictor of disease in adulthood as the waist measurement and BMI. Researchers assessed anthropometrics, or body circumferences in more than 1100 children ages 6 to 18. Neck circumference was determined based on the widest measurements attained at the neck. Upon review, correlations were found between Neck Circumference and BMI values previously associated with diseases such as obstructive sleep apnea, diabetes, or high blood pressure in adults. In an interview with the researchers, the authors suggest that one major drawback of using BMI is that it does not address abdominal adiposity directly whereas neck measurements are directly linked to waist measurements. In addition, the researchers felt that neck measurement would present a more meaningful value to patients compared to the BMI. They recognize that because the patient does not understand BMI as he/she understands weight or height, the perception of the BMI value is often not sufficiently threatening to instigate behavioral change. Finally, the reliability of repeat measurements for the neck is greater than the waist measurement, because experts continue to disagree on the best point to record the waist measurement. For example, ACSM uses the smallest measure between the sternum and the navel, however, that value can often be deceptive if the individual carries most of his/her abdominal fat below the navel. This is an original study. Hence, neck circumference and risk stratification charts are not currently available. However, you should expect to see these become available in the near future. In the meantime, rely on direct measurements of body fat along with anthropometric measurements to predict health risk in clients. Madison Park. Can Neck Measurement Indicate Body Fat Better than BMI? CNN.com July 6, 2010._____Interrupted Practice Better for Skill Development One of the biggest challenges for an individual starting a strength-training program is learning the basic lifts or movements. From age to muscle imbalances, and time constraints the ability to memorize the intricacies associated with lifts such as the squat, lunge or press can either lead to a sense of enjoyment or discomfort with exercise. Moreover, results are based on the capacity to load these exercises. However, if technique is not solid loading is not possible. The challenge for fitness professionals is to understand the best methods for introducing and progressing the lifts to empower clients. A recent study sheds light on part of this process. Researchers at the University of Southern California recently determined why intermittent practice is associated with better memory of a task than constant practice. Fifty-nine participants performed a challenging arm movement practicing it consistently or in a varied structure with related tasks while brain activity patterns were assessed. As expected, those who participated in the mixed practice design improved their skill to a greater degree than those who practiced the arm movement consistently did. Four hours after practicing the task, researchers exposed the participants to magnetic stimulation of either the prefrontal cortex or the primary motor cortex of the brain. This allowed the researchers to map the neural pathways associated with learning and memory of the task. They determined that the broken practice design stimulated the prefrontal cortex to a greater degree than constant practice. The researchers believe that by breaking up task practice you force the brain to initiate learning from scratch each time you repeat the activity. On the other hand, consistent practice only achieves activation in the primary motor cortex, which does not lead to deeper processing and learning. The findings in this and previous studies support the use of strategies such as supersets and circuit training when teaching new movement patterns. Moreover, the use of complex movements such as multi-directional lunges and Turkish get-ups to name a couple, require greater learning before load can be manipulated to build strength. Strategically placing exercises such as these throughout the workout may facilitate better learning than simply doing 3 sets of 10 repetitions consecutively. Press Release. Mixed Practice Makes Perfect. University of Southern California. July 12, 2010._____Do Jumps Trump Weight Training for Runners? Developing complimentary strength and power training programs for endurance athletes is a continuing challenge. First, endurance athletes are hesitant to introduce weight training for fear of adding additional body mass, which is assumed to result in slower running. Second, endurance athletes, many of whom have restrictions on training time, simply can't find time to add additional training. Last, recently researched protocols suggest that low-rep, high load and plyometric-based training have the greatest potential to improve performance. It's been previously determined that both traditional strength training and plyometric "jump" training improve running economy; one component of running that leads to improved performance. How much or what types of strength and jump training achieve this result continue to be researched. In a recent study published JSCR, researchers found that plyometrics improved the energy costs of running better than dynamic weight training in well-trained male runners, but can you trust the results? Thirty-five athletes completed either 8-weeks of plyometric training, dynamic weight training, or no additional training (i.e. control). This training was complimentary to an endurance running program that consisted of two interval-training sessions per week, and one long continuous run weekly. In addition to running, the plyometrics group incorporated depth jumps from a box, while the weight-training group did squats on a specially designed Smith Machine that eliminated the eccentric component of the lift. Both groups completed between 3 and 6 sets of 8 repetitions with 3-minute recovery intervals just once weekly. Although both groups improved running economy, the plyometric group improved to a significantly greater degree. It is interesting to note that the plyometric group incorporated a jumping activity with a significant eccentric component, while they removed the eccentric component from the weight training group. Unfortunately, this structure makes it difficult to formulate a comparison because the two activities were respectively dissimilar. Although support for the use of plyometrics is confirmed in this study, it would be difficult to discount the value of weight training based on the results of this study. Berryman, N. et al (2010) Effect of Plyometric vs. Dynamic Weight Training on the Energy Cost of Running. Journal of Strength & Conditioning Research. 24(7): 1818-1825.
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