This article was featured in the Sept/Oct 2008 edition of ISSA's Associate Newsletter. To sign up for this bi-monthly newsletter, please visit: http://ipost.com/issa/prefs

One word, one food, one macronutrient has seemingly caused more conversation and controversy in the past few years than any of the other dietary substances combined. This staple of the modern American diet is either being vastly overeaten, under-eaten, or completely abandoned all across the country, and I think that it's time we found out the truth about the infamous carbohydrate. Atkins and South Beach philosophies aside, we'll focus on modern research to learn more about the carbohydrate as a substance, as well as an appropriate and recommended intake.

Let us first identify carbohydrates as a substance. Carbohydrates are your body's primary source of energy. They can be found in grains, starches (pasta, potatoes) vegetables and legumes (beans and peas). They're also found in sugar and sweets, including fruit and candy, and even in dairy products. Each gram of carbohydrate contains 4 calories. During digestion, your body converts carbohydrates into sugar (glucose). The sugar enters your bloodstream, where it is transferred to individual cells to provide energy. Some of the extra sugar is stored in your liver and muscles as glycogen. Your muscles normally store only small amounts of glycogen--enough to support you during activities such as recreational biking or swimming, weightlifting, and 5- to 10-kilometer runs. But depending on your level of fitness, your muscles may run low on glycogen if you exercise intensely for more than 90 to 120 minutes. In turn, your stamina and performance may suffer. This can be an issue during activities such as long-distance running, swimming, cycling, soccer and triathlons.

Endurance exercise is not the only form of training and competition in which carbohydrate depletion can compromise performance; it can also occur during high-intensity exercise as well, especially during activities that involve high quantities of repeated anaerobic bouts. This depletion can then trigger a phenomenon known as gluconeogenesis, a process by which additional energy is produced by the synthesis of glucose from protein and fats. Unfortunately, a prevailing disadvantage of this compensatory energy-producing mechanism is the potential loss of muscle tissue. This fact, of course, flags the significance of adequate carbohydrate intake and its role in the maintenance of the body's protein stores.

Insufficient carbohydrate supplies can also affect the brain, since the primary fuel for the brain is glucose. Impaired central nervous system (CNS) function is apparent during starvation and prolonged endurance exercise, when depleted glycogen stores can induce feelings of dizziness and general malaise. In the case of low-carbohydrate diets, prevalent side effects are symptoms of fatigue, weakness, and hunger.

Conversely, excess carbohydrate intake can lead to undesired weight gain. Ingested carbohydrates are converted to muscle and liver glycogen, but once their carrying capacity is achieved, the rest is converted to fat--an unwanted result for those who want to lose weight and improve body composition. It is also critically disadvantageous for athletes engaged in events in which weight gain diminishes performance (e.g., distance running, swimming, etc.). This signifies the extreme importance of a dietary regimen that maintains a balance between adequate energy production and physique maintenance or improvement.

Given all of this information, let's take a look at how many daily carbohydrates are necessary but not excessive. This is a complicated question based on the various and particular needs of individuals. For the "average" person wanting to increase muscle and decrease fat, ISSA's 3-2-1 Rule--1 part fat, 2 parts protein, and 3 parts carbs--is a good general reference when deciding on your daily meals. Additionally, we also recommend that out of that 3 parts carbohydrates, no more than 25% be comprised of simple carbohydrates such as sugars and processed foods. For instance, if an individual required 2400 calories per day based on BMR and activity level, each "part" would translate to 400 calories (2400/6 parts = 400). Therefore, 1 part fat would equal 400 calories from fat, 2 parts protein would equal 800 calories from protein, and 3 parts carbohydrates would equal 1200 calories from carbohydrates. Of those 1200 carb calories, a maximum of 300 would come from sugars and processed foods.

ISSA's Zig Zag approach is another helpful tool when deciding what to eat and when. This approach focuses primarily on the manipulation of calories and carbohydrate intake on a day-to-day basis, emphasizing days of increased calories and carbohydrates (particularly on days of high intensity training) versus days of decreased calories and carbohydrates (particularly on rest days) to maximize nutrients for energy and recovery, but with the intermittent low cal days for stimulating metabolism and maximum recovery without overeating.

In reference to general carbohydrate intake percentage, I recommend that the average active individual ingest roughly 50% to 55% of their daily calories from carbohydrate sources, preferably complex carbohydrates. Mind you, this is a general recommendation based on low to moderate activity levels. For those who are more active or training rigorously for an event such as a triathlon or a sport, that carbohydrate percentage may need to be increased to 60% or higher to account for the additional energy needed to perform at maximal levels. If you are worried about carbohydrate intake affecting your physique, remember, the Zig Zag approach is a perfect remedy for this. On days that you plan to exercise or train at high intensity levels for an extended period of time, more carbohydrates are naturally required; but days that are going to be used for rest and recovery, cut back slightly on your calories and carbohydrates, and focus more heavily on lean sources of protein in your meals to reinforce muscle recovery. This way, you'll rarely have to worry about reaching a surplus of carbohydrates that your body can't process and use for fuel.

I know that most people reading this would love for me to offer a specific number of carbohydrates per pound per day as a scientifically proven recommendation, but that is just not the case, not yet at least. Our lives are just too different from one another to benefit from a precise recommendation. What I can say is that studies are being conducted daily on the topic of carbohydrate needs for both fat loss and performance enhancement all over the world, so new and exciting developments are sure to find us in the near future. In the meantime, our recommendation is to keep your carbohydrates around that 50% to 55% range, trying to derive most of your carbs from high quality, complex carbohydrates, which will inevitably supply you with adequate mental and physical energy to be successful throughout your day. Whatever you do, stay away from any diets or "experts" advising you to severely limit your carb intake for an extended period of time. This is both counterproductive and potentially dangerous, and for an athlete can be disastrous to performance. Carbohydrates are one of the most vital nutrients offered to us, so enjoy them, just not too much.

It's not how much you weigh, it's how much of your weight is fat. Simple test determines your fat content, health risks.

Carpinteria, CA – August 20, 2008 – Within the past week, the American Heart Association, Journal of the American Medical Association and the American Cancer Society have cited new studies that seem to indicate the deteriorating health of Americans may not be related solely to weight--but to declining overall fitness levels.

While it is virtually impossible today to remain oblivious to the importance of exercise for staying healthy, there has been a marked emphasis on "weight" versus "fitness" in western society's perception of health and wellness. Consequently, many people of "normal" weight continue to be uniformed of the fact that they may still be at risk for elevated levels of blood pressure, cholesterol, triglycerides, and blood sugar if they lead a sedentary (inactive) lifestyle.

It has long been known that there are adverse effects associated with physical inactivity. Adults who are less active are at greater risk of dying of heart disease and developing diabetes, colon cancer, and high blood pressure. Illnesses related to physical inactivity and poor diet cause at least 300,000 deaths each year in the U.S.

Body mass index (BMI), which is calculated through a height-to-weight ratio alone, has been the standard method of measuring a person's "fatness" or "thinness" since 1950's and 60's, when obesity was becoming a noticeable medical concern in the U.S. As a result, being at a "normal" BMI weight is not necessarily a reliable indicator of health.

In fact, physically active individuals who have more lean tissue than their sedentary counterparts, as well as taller people, often have a BMI that classifies them as obese when they actually have healthy body fat levels. Likewise, and more dangerous, slender or thin but inactive individuals often have a BMI that puts them within normal, or even underweight, ranges when they actually have high levels of body fat.

Because of the overemphasis on BMI that has developed over the last few decades, these "skinny fat" people often remain unaware that they are at an elevated risk for developing diseases typically associated with obesity until they are already facing health issues.

According to the International Sports Sciences Association, an organization that has educated and certified personal trainers for more than two decades, using a quick but reliable method of measuring various body circumferences (e.g. neck, thighs, upper arm, waist, hip) to assess total body fat better determines one's body composition (fat vs muscle) than BMI alone. Measuring circumferences also provides personal trainers and clients with a very easy way to gauge clients' progress. "For people to begin to take a proactive approach to their health, they really need to know what their percentage of fat versus muscle is." said Dr. Sal Arria, CEO and Co-Founder of the ISSA. Dr. Arria goes on to add, "Most studies have shown that by just adding ONE circumference measurement at the waist to BMI, you can better predict a patient's risk for type 2 diabetes and for all-cause mortality. Waist circumference is also about twice as good at predicting future coronary heart disease than BMI alone."

The ISSA believes that personal trainers and health clubs should be utilizing circumference measurements as another tool to assess body fat because trainers can achieve proficiency with a few hours of practice and, when done properly, the results can be replicated.

Patrick Gamboa, ISSA Vice President of Education, cautions that a person's true fitness cannot be assessed by body measurements alone. True fitness must also take into account strength, aerobic capacity and flexibility measurements to most accurately predict longevity. Most gyms offer this type of assessment for free to their members.

About the ISSA Since 1988, the International Sports Sciences Association (ISSA) has provided certification and continuing education to more than 100,000 wellness professionals in 85 countries around the globe. The ISSA offers a core personal training certification as well as eight additional specialized fitness certifications.

August 7, 2008 - Carpinteria, CA - As the world celebrates the athletic achievements of its citizens at the Olympics this month, the International Sports Sciences Association would like to honor all fitness professionals from every nation that have helped these athletes reach Beijing. Often, the services that personal trainers provide these athletes help get them to the games and, in many cases, the podium.

ISSA would like to encourage individuals who champion health and wellness in their own spheres of influence to further their commitment to fitness by turning their passion into a career as a personal trainer. From August 8 through 24, students can enroll in any ISSA fitness certification for $100 off each course enrollment--more than 15% off the normal cost.

As public outcry grows louder for the current U.S. healthcare system to shift its focus from treatment to prevention, Dr. Sal Arria, ISSA CEO and co-founder as well as a doctor for the US Track & Field team at the 1984 Olympic games, adamantly believes that health and fitness professionals will play a critical role in the healthcare system of tomorrow. As a result, ISSA has chosen to develop certifications that address the needs of special populations--including sports conditioning, youth fitness, senior fitness, fitness therapy, and nutrition. OTHER ISSA CHAMPIONS In addition to founders Dr. Sal Arria and Dr. Fred Hatfield, the ISSA is proud to include among their ranks several senior staff members and advisors who have had the opportunity to work with literally thousands of athletes worldwide – many of whom have gone on to impressive careers. Two notable standouts are ISSA professors Dr. Jack Barnathan and John Schaeffer. Dr. Barnathan serves as chiropractor to a host of pro and Olympic athletes including Dara Torres. John Schaeffer, MFS, MSS, MPN, serves as a trainer to several prominent Olympians, including Apolo Ohno, Allison Baver, Liam Ortega, Giddeon Massie and Mark Fretta.

About ISSA Since 1988, the International Sports Sciences Association (ISSA) has provided certification and continuing education to more than 100,000 wellness professionals in 85 countries around the globe. The ISSA offers a core personal training certification as well as eight additional specialized fitness certifications.

This article was featured in an archived edition of ISSA's Associate Newsletter. To sign up for this bi-monthly newsletter, please visit: http://ipost.com/issa/prefs

Summertime is approaching quickly and for most of us, that means days of fun at the beach, hanging out by the pool, and afternoon barbecues. It also means it's time to kick our training into high gear so that when the heat turns up, the clothes can come off with confidence, ready to show off that body you've worked so hard for all year long.

Certainly you've heard from at least a couple of fitness enthusiasts claiming high repetitions are key to getting "cut." However, science tells us just how accurate this common belief is: it's NOT! In fact, there is no logical or physiological reasoning for this type of training, and the masses that have spent hours of training time pumping out 30+ repetitions per set have been sacrificing some true fat burning, body shaping potential, and could be impeding their progress.

When trying to shape or tone your body, there are a couple of things that are important to remember. First of all, there is no such thing as spot reducing. It is impossible to target a location on your body that YOU decide to pull and utilize fat from. Doing 20 repetitions of chest presses is not going to magically sculpt your chest or give it a harder look. The ultimate goal of a sculpting or cutting program is essentially to increase the percentage of lean body mass (muscle) and decrease fatty tissue so that the muscles will be more visible. The only appropriate way to do this is through a resistance program that promotes muscle hypertrophy (term for the growth and increase of the size of muscle cells) and a diet that promotes fat loss. Science has proven in both men and women, that only resistance training that is high in intensity, utilizing 8-12 repetitions, moderate to heavy resistance and a maximum of one minute rest between sets will maximize serum testosterone and growth hormone levels, thus allowing for successful recovery, adaptation, muscular growth and hypertrophy.

Since we have established that a primary focal point of getting toned is body fat reduction, than obviously nutrient and caloric intake are paramount. Consider that 1 pound of fat is equal to 3500 calories. In order to lose 1 pound of fat per week, logically you'll have to expend or burn 3500 calories through diet and/or exercise over the course of that week to achieve that objective. As suggested by the ISSA's zigzag diet method, the ideal way to lose fat while preserving muscle is to consume fewer calories on non-exercise days and slightly increase calories on days of moderate to intense activity to provide the body with fuel it needs for the workout. Some other helpful hints include consuming 5 to 6 smaller meals throughout the day. This will ensure that your metabolism stays elevated at all times and will your body will remain in a constant fat-burning state. Also, limit your intake of saturated fats and simple sugars, and focus instead on consuming lean sources of protein and low glycemic carbohydrates. It is also very important to keep your water intake high at a level of around 0.6 ounces per pound of body weight.

Finally, what would an efficient fat-burning program be without some good old fashion cardiovascular exercise? If you want to maximize your body's fat burning capacity and also minimize muscle loss (catabolism) that inevitably accompanies a fat-burning cycle, I suggest that you do your aerobic work directly after your resistance training at less than 75% of your maximum heart rate. If you are doing cardiovascular work on your off (non-resistance training) days, then I recommend that you train at 85% to 95% of your max heart rate for the first 30 minutes and drop the intensity to 75% for the last 20 to 30 minutes. These types of workouts will shoot your resting metabolism through the roof and will allow you to burn maximum amounts of fat even when you are at rest. That's the skinny folks. Take the "light weight and higher reps" philosophy and throw it away with the multitude of other training myths you've heard through the years. Following this misguided method will only put you at risk to lose strength and muscle mass, and will not assist you in burning fat or defining your physique. Stick to the basic principles stated above and you should be well prepared to shed fat, and eventually clothing, come summertime!

As always, we want to cover fitness topics that you want to read about. If you have a topic of interest that you'd like to see in the next issue, send me an email at FocusOnFitness@issaonline.com.

Speak out on the latest news release regarding different nutritional strategies! Which do you find works best for your clients or you personally? Do you agree with the study's findings?

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DENVER, July 16 /PRNewswire/ -- The results of a two-year study, released today in The New England Journal of Medicine, comparing a low-carbohydrate diet like the Atkins Nutritional Approach(TM) with Mediterranean and low-fat diets, found that low-carbohydrate diets are more effective in achieving weight loss than the other diets, and supported cardiovascular health with favorable cholesterol and cholesterol profile results.

The study compared three diets -- low-carbohydrate, low-fat, and Mediterranean -- and followed more than 300 obese patients for two years. All the study participants consumed similar number of calories.

Those following the low-carbohydrate diet experienced a mean weight loss of more than 10 pounds. Their mean weight loss was 40 percent greater than those following the low-fat diet and about 7 percent greater than those following the Mediterranean diet.

This new study confirms that diets such as the Atkins Diet(TM) that are focused on reduced levels of carbohydrates provide a roadmap to successful weight loss and weight management with significant health benefits.

Participants following the low-carbohydrate diet consumed more protein, fat and cholesterol than the other diets, but experienced the best results comparing cholesterol ratios, and comparable improvements in health measures such as liver function and levels of cardiovascular disease. Among the low-carbohydrate participants, the reduction in the ratio of total cholesterol to HDL (good cholesterol) was significant -- a relative decrease of 20 percent -- and better than the other diets.

"This study adds to the growing body of evidence that Atkins continues to be on the cutting-edge of science," notes Vice President of Education and Nutrition, Colette Heimowitz. "Individuals who are looking to lose weight successfully and develop healthy lifelong eating habits can rely on Atkins to provide them with the tools they need to achieve their goals."

The study published in The New England Journal of Medicine was conducted by researchers at Ben-Gurion University of the Negev in Beer Sheva, Israel and at Brigham and Women's Hospital's Channing Laboratory.

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As a fitness enthusiast, you witness every single day the ways in which fitness can change people's lives for the better. Right now, there's a bill in the U.S. Congress that could save Americans money in their efforts to stay healthy. The Personal Health Investment Act (H.R. 245) would allow people to use up to $1,000 annually for exercise and physical fitness programs (like personal training!) along with certain exercise equipment and children's sports league fees with pre-tax dollars.

Make sure your voice is heard when this bill comes to the floor by encouraging your congressional representatives to pass the PHIT Act via the link below: http://www.votervoice.net/Core.aspx?AID=469&APP=GAC&IssueID=8029&SiteID=1

By Herve Bensabat, CFT, CSCS, NASM-CPT is a strength and conditioning specialist and personal trainer. He is also certified in post-rehabilitation fitness therapy and performance nutrition with the International Sports Sciences Association.

Visit Herve online at www.workout-from-home.com

Part 1 of 4

This article was featured in the June 2008 edition of ProTrainerOnline. To sign up for this bi-monthly newsletter, please visit: http://ipost.com/issa/prefs

Give your clients the gift of a lifetime. Teach them the true value of robust health. Impart the notion that physical activity is a lifelong endeavour, and inspire them to truly live the fitness lifestyle. It doesn't cost a dime. And it won't take you anymore time than you're already awarding them...

We instinctively know this. Exercise is beneficial for your health.

Laboratory and population-based studies have clearly demonstrated that regular exercise prevents occurrences of cardiac events, reduces the incidence of strokes, hypertension, diabetes and other chronic diseases, and substantially increases energy expenditure (1).

Other scientific studies have postulated that physical activity may also lessen anxiety and depression, enhance feelings of well-being, and improve sleep (2). Doctors, clinicians, health organizations, insurance companies, and health care providers all concur. No one disputes the importance of incorporating regular exercise and healthy nutrition into your lifestyle.

Most public health agencies across the nation agree that just one hour of physical activity out of the 24 hours in your day is all that is needed to reduce the risk of disease, improve your health, and start living the fitness lifestyle.

And the great news is all the agencies are in agreement that health benefits can accrue by simply adding up brief activity periods of at least 10 minutes each throughout the day. What could be simpler?

While the benefits of exercise have been well documented in the scientific literature, some have criticized the collective efforts of public and private agencies and mass media awareness campaigns to propagate the physical activity message, claiming that not enough is being done to reach the North American audience.

Even if this is so, you would have to concede that common sense dictates that we all inherently know deep down that exercise is good for us and that we should all be more active on a regular basis.

Indeed, some research is now pointing to the fact that more and more Americans are cognizant of the health benefits and the need for physical activity. Despite this increased interest, as much as half of the population does not exercise as per the U.S. Centers for Disease Control and Prevention (CDC) and the American College Of Sports Medicine (ACSM) physical activity recommendations. And one quarter or more do not exercise at all (3, 4).

In Canada, the findings are similar. Almost two thirds of the population fail to meet the guidelines set forth in the Canada Physical Activity guide (5).

Perhaps more intriguing is the disconcerting reality that of the small percentage of sedentary individuals who begin regular physical activity, almost half of them will quit within three to six months – and the drop out rates for previously active individuals are no better (3).

"Physical activity" as defined by the agencies consists of such accommodating activities as, for example, walking, gardening, biking, swimming, raking leaves, and dancing. Why then do we fail to meet even the most basic requirements knowing our health hangs in the balance?

The answer to this question is as diverse as the population itself.

The most often cited factors are lack of time, lack of energy, inconvenience, and proximity, access to, and affordability of the activity or exercise facility. Environmental constraints such as weather, traffic, crime, safety, and lighting are also important considerations. For sub-populations such as older adults or the overweight, it is not uncommon to learn that fear of injury or fear of embarrassment can also act as a hindrance.

While this short list represents just a fragment of the constellation of factors acting as barriers to adopting a fitness lifestyle, fitness professionals should appreciate that the most potent reasons people have are rarely verbalized. These have to do with deeply ingrained belief systems, past experiences, or negative perceptions related to exercise.

Clearly, the issue of adherence is not an insignificant one.

Although we commonly think of client goals in terms of toning up, losing weight, building muscle, or improving performance, it is important to remember that as fitness professionals, our primary chief obligation toward our clients is to help them establish a lifelong habit of active living and healthy eating long after they no longer train with us. This cannot be over-emphasized.

It's fairly safe to assume that individuals who seek out the services of certified fitness trainers have already made the decision to become active, or are about to. Others looking for trainers may already be active but are searching for professional guidance to advance their health, fitness, or athletic goals.

At the other end of the spectrum, those that are inactive or insufficiently active are either contemplating the decision but haven't as yet committed, or they are not even considering it. Part of the reason why a greater emphasis needs to be placed on adherence is because the issue is not always so clear cut. Unfortunately, it is not simply a matter of belonging to one group or the other. Thus, identifying those at risk is not a simple matter.

For many of us, the decision to become active or inactive is cyclical in nature. There are moments in our lives when we are engaged in fitness and moments when we are not. Even the most fervent fitness enthusiasts amongst us are not immune to disruptions despite our best intentions, either because of illness, injury, job change, geographic move, travel, holidays, competing priorities, growing family or work demands.

For first time exercisers especially, the stark reality is that many attempts at physical activity are needed before a durable habit can be formed. Recognizing that exercise is voluntary, time consuming and competes with many other daily responsibilities is the first step to appreciating the complexities involved.

While the relatively short time we share with our clients does not guarantee they will remain active over the course of a lifetime, we can substantially influence and increase the chances of success by educating them about the role physical activity plays in reducing the risk of disease and repeating this message often, by ensuring that their experiences with physical activity and exercise are positive ones, and through the use of a multitude of strategies to help shape and establish a durable habit.

Every training session should be viewed as an opportunity to promote adherence.

For fitness professionals wanting to make a difference in the lives of those around us, this is an area where we can truly be of service and have a lasting impact on the lives of others.

This series of articles will outline for you some of the steps you can take today to educate, encourage, and inspire your clients to get active and stay active throughout the seasons of their lives.

The psychology literature is filled with proven principles to effectuate behaviour change and encourage adherence. Every good personal trainer is already aware of the battery of tools and methods available to them. Let me outline in bullet form some of the more common approaches used to facilitate this task...

• Increasing knowledge (constantly educating your client)

• Rewards system (rewarding oneself after accomplishing a task)

• Commitment system (committing oneself by making promises known)

• Motivational reminders (posting notes, etc., in visible places)

• Goal setting

• Learning stress management (ways of coping with stress)

• Learning time management (scheduling and setting time aside)

• Feedback system (providing positive feedback)

• Written contracts / written agreements

• Enlisting social support (family, friends, groups, etc.)

• Use of role models

• Use of LISTS:

Exercise / physical activity log Nutrition log Mood diaries Listing advantages Listing barriers Cost-benefit / decisional balance sheet • Progress analysis (discussion of progress / new & regular assessments)

• Personal responsibility & accountability (encouraging self-reliance, self-efficacy, etc.)

• Substitutions system (substituting alternative tasks to reduce aversion)

• Contact support (periodic telephone calls, letters, postcards, e-mails, newsletters, etc.)

Adding to, and combining some of these methods together to the ones you are no doubt already employing can magnify the impact you are having.

In Part 2 of this series, I will share with you some of the principles I use to service my clients beyond the traditional exercise training program to foster the notion of exercise adherence over the span of a lifetime and to fully live the fitness lifestyle.

References

American Association of Cardiovascular and Pulmonary Rehabilitation. Guidelines for Cardiac Rehabilitation and Secondary Prevention Programs. 4th ed. Champaign, IL. Human Kinetics. 2003 Ferketich AK, Schwartzbaum JA, Frid DJ, et al. Depression as an antecedent to heart disease among women and men in the NHANES I study. Arch Intern Med 160 (2000):1261-1268. U.S. Department of Health and Human Services. Physical Activity and Health: A Report of the Surgeon General. Atlanta: U.S. Department of Health and Human Services, Centers for Disease Control and Prevention, National Center for Chronic Disease Prevention and Health Promotion, 1996. U.S. Department of Health and Human Services. Healthy People 2010: Understanding and Improving Health. Washington, DC: U.S. Department of Health and Human Services, 2000. Canadian Fitness and Lifestyle Research Institute (CFLRI). 1997 Physical Activity Monitor. Ades PA, Waldmann ML, McCann WJ, et al. Predictors of cardiac rehabilitation participation in older coronary patients. Arch Intern Med 152 (1992):1033-1035. Petrella RJ, Koval JJ, Cunningham DA, et al. Can primary care doctors prescribe exercise to improve fitness? The Step Test Exercise Prescription (STEP) project. Am J Prev Med 24 (2003): 316-322. Dishman R. Exercise Adherence: Its Impact on Public Health. Champaign, IL: Human Kinetics, 1988. Vuori I. Perspectives on Health and Exercise. Edited by Mckenna J, Riddoch C. New York: Palgrave Macmillan, 1997. Powell KE, Heath GW, Kresnow MJ, et al. Injury rates from walking, gardening, weightlifting, outdoor bicycling and aerobics. Med Sci Sports Exerc 30 (1998): 1246-1249.