How Muscle Mass Affects Metabolism

The main purpose of weight training is to increase muscle mass and strength. This mode of exercise has other benefits as well including enhancing bone density, burning calories, reducing the decrease in muscle mass as we age, increasing metabolism, etc. Increasing metabolism is where helping to reduce body fat comes in. Muscle is metabolically active tissue. Every pound of muscle requires energy to maintain itself. Therefore, the more muscle you have, the more calories you burn even when you’re just sitting around.

Also, after age 30, adults lose about a 1/3 - 1/2 a pound of muscle each year without strength training. So even with aerobic exercise and a moderate diet, if you're not strength training you could have a higher percentage of body fat. Less muscle means fewer calories burned and more calories stored as fat. The bottom line with muscles: "use them or loose them." Strength training will help reduce the amount of muscle mass lost with age and help reduce body fat.

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ACSM Fitness Focus: What is Oxygen Consumption?

Oxygen consumption is frequently used when discussing exercise, but what it is, what it means, and why it is important is often misunderstood.

Background
Our bodies need a constant supply of energy to sustain life. Energy is used to contract skeletal muscles, pump blood, sustain tissues, and many other functions. The form of energy the body needs for these processes is adenosine triphosphate (ATP). This high-energy compound is split apart, releasing energy to perform cellular work. Think of it as the gasoline for your cells. Because the body does not store large quantities of ATP, our bodies must continually make more. Although there are processes that can produce ATP without oxygen (O2), these anaerobic systems are limited in their capacity to produce ATP. The greatest capacity to produce ATP is through the breakdown of carbohydrates, fats, and to some extent proteins. To make ATP from these nutrients, O2 is required. Ultimately, oxygen-requiring - also known as aerobic - processes are necessary to sustain the body's energy needs.

What is Oxygen Consumption?
Oxygen consumption (V˙O2) is the amount of oxygen taken in and used by the body per minute; thus, it is the rate of oxygen use. V˙O2 is sometimes expressed in liters of O2 per minute (liters per minute). Alternately, it can be expressed as a function of body weight, frequently as milliliters of O2 per kilogram of body weight per minute (milliliters per kilogram per minute). Expressing V˙O2 as a function of body weight is important when comparing people of different sizes during exercises such as running.

How is Oxygen Consumption Measured?
When we inhale, 20.93% of the air that we bring into our lungs is O2 and 0.03% of the air is carbon dioxide (CO2). When we exhale, the percentage of O2 is lower (we consume O2), and the percentage of CO2 is higher (we produce CO2). In exercise physiology laboratories, machines that measure the amount of air inhaled or exhaled and devices that measure the percentage of O2 and CO2 in expired air are used to calculate V˙O2. There also are portable devices that can be used outside laboratory settings to measure V˙O2 during various types of activities (e.g., playing golf, performing yard work, etc).

Why is it Important?
V˙O2 reflects energy expenditure, meaning that measuring V˙O2 provides an estimate of calories burned. Approximately 5 kcal of energy are expended for every liter of O2 consumed. Thus, a person with a V˙O2 of 1 L/min is burning 5 kcal each minute. As one exercises harder, V˙O2 rises, meaning that energy expenditure is higher. The interrelationship of the type and intensity of activity, O2 consumed, and energy used allows researchers to estimate the caloric expenditure for different tasks. This information can be used to shape exercise plans to meet weight control goals.

Information about V˙O2 also can be useful for athletes. Economy tests examine the relationship between work performed and energy expenditure during exercise. Athletes who are able to move smoothly, without wasting energy, perform better. For example, a person who runs with his arms out to the side of his body uses extra energy but that doesn't help him run faster. Coaches closely examine the movement patterns of athletes to improve the economy of effort. Maximal V˙O2 (V˙O2max) is another measurement often used by coaches and athletes (see Fitness Focus from issues 9:3, 9:4, and 9:5 published in 2005). V˙O2max provides a measure of the maximal ability to perform high-intensity aerobic work. This value is strongly associated with performance and health.

© 2010 American College of Sports Medicine Author: Thompson, Dixie L. Ph.D., FACSM, ACSM'S Health & Fitness Journal: January/February 2010 - Volume 14 - Issue 1 - p 4

What to Look for When Hiring a Personal Trainer

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Whether you’re a beginner looking for a new workout program, an athlete wanting to enhance a performance skill, or a sports enthusiast looking to better your game; a personal trainer can give you the tools and know-how to help you achieve your goals. Personal trainers either work in health and fitness centers or they work privately, visiting their clients at home or the office. While there’s no shortage of personal trainers, finding and choosing a trainer that’s right for you can be difficult and even intimidating. So how do you find a trainer that’s right for you? What qualifications should you look for? Here are a few questions you should ask before hiring a personal trainer (PT).

Are They Certified?
There are literally hundreds of PT certifications. Some just require payment for a certificate, while others require a Bachelors Degree in the health/fitness field before you can even sit for their comprehensive and lengthy exam. With so many reputable (and not so reputable) certifications out there, there’s no wonder people are confused. The bottom line: All PT’s should hold a nationally recognized certification accredited by The National Commission for Certifying Agencies (NCCA). Some of the more popular PT certifying organizations include: The American College of Sports Medicine (ACSM), American Council on Exercise (ACE), and National Strength and Conditioning Association (NSCA), just to name a few. When in doubt, find out the name of the organization your trainer is certified by and go to their website or the NCCA website. If they are accredited by NCCA, it will be listed on the website.

Are They Insured?
Most trainers working at a gym are insured through their employer. However, if they are working as an independent contractor they need to carry their own liability insurance. Trainers that come to your home or outside trainers going to your gym for the PT session are most likely contractors. If so, ask for a copy of their certificate of insurance and make sure it’s renewed when needed.

Do They Have a College Degree in the Health/Fitness Field?
Ask your potential trainer if they have a degree in the fitness field. This is not necessarily a requirement, and not all PT’s have a college degree, but those that do generally have a greater background in and understanding of anatomy, physiology, kinesiology, etc. This level of education can come in handy for those with special needs such as, medical limitations, injury recovery, cardiac rehabilitation, or even athletes looking to enhance their sports performance.

What is Their Experience and Area of Expertise?
It goes without saying; experience brings knowledge. Perhaps you are looking to achieve a specific goal such as body building, reducing your blood pressure so you don’t have to take medication or lowering your risk of heart disease. Find a trainer with experience in that specific area. A trainer whose area of expertise is body building may not be a good choice if you are trying to focus on health issues.

Do They Follow the Code of Ethics?
Each certifying organization has their own written Code of Ethics that trainers must follow. The Code of Ethics is intended to establish and maintain high standards and professionalism for personal training professionals. It’s understood that the welfare of the client is central to all considerations in the trainer-client relationship. For example, a PT should never recommend a product, such as supplements, when the trainer receives a commission for its sale. This is often done in gyms and is a conflict of interest. PT’s can offer diet and nutrition education backed by national organizations such as the American Diabetes Association, American Heart Association, Food Guide Pyramid, etc., but unless the PT is a Registered Dietitian, they should not be giving clients meal plans. This is beyond the scope of their education and practice.

Do They Have a Compatible Personality?
You can have a well-educated and highly experienced PT with all the credentials listed above, but your personalities just don’t click. That doesn’t mean you haven’t found a great PT, but maybe just not the one that’s right for you. You’re going to be spending a lot of time with this person so you want to make sure you find a trainer that fits your style.

Do They Have References?
Ask the personal trainer for names, phone numbers and even testimonials of other clients he/she has worked with, particularly those who share similar traits and goals. Find out if the trainer was professional, punctual and prepared, and whether the client’s individual needs were addressed. Inquire if the trainer was a good listener, focused on client challenges and goals, and tracked progress.

What are the Rates?
Personal training rates vary by geographic location, trainer qualifications, and the type of training your looking for. Expect to pay more for a trainer that is well educated and/or comes to you, especially if they bring their own equipment. Whatever you choose, personal training is an investment in your health. A personal trainer gives you guidance on reaching your goals, education about strength training and cardiovascular exercises, and general nutrition. They also help keep you accountable, motivated, and track your progress.

Working out should be fun! Just be sure you choose the right personal trainer for YOU. If you do, you'll be more likely to stick to those workouts that will produce amazing results.

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