If you are looking to keep the pounds off as you age, you will need to add some weight now - by lifting it, that is.  Research findings presented in the July 2010 issue of Medicine & Science in Sports & Exercise reveal that resistance training by postmenopausal women prevents weight gain and improves body composition.  The investigation was a secondary analysis derived from The Bone Estrogen Strength Training (BEST) study which evaluated the effects of weight training on bone mineral density (BMD) in early postmenopausal women.  For the intitial BEST investigation, subjects were first grouped according to treatment with or without hormonal therapy; then, they were randomly assigned to either an exercise or nonexercise group within their respective hormonal therapy category (those on hormonal therapy versus those who were not on hormonal therapy).

In this secondary investigation, researchers set out to examine the effects of resistance training on soft tissue changes and weight management in postmenopausal women.  Subjects included 122 females (mean age 56.3 years, give or take 4.3 years) who were previously sedentary.  After the the first year of intervention, the control subjects were allowed to begin the prescribed exercise regimen, or in other words "crossover."  This created 3 test groups: exercisers - those who were assigned to the exercise group at baseline (n=65); crossovers - those who crossed-over to the exercise program at one year (n=32); and true controls - those women who remained sedentary (n=25).

Exercisers and crossovers participated in 8 core resistance training activities for 2 sets of 8 repetitions each (at 70-80% 1-repetition maximum) on 3 nonconsecutive days/week.  They also engaged in various stretching, balance, and progressive weight bearing activities (e.g., stair stepping with weighted vests).  Exercise frequency and workloads of the various exercises were recorded.  Body weight and fat were measured at baseline and annually for 6 years using anthropometry and dual-energy x-ray absorptiometry.

Researchers found that over the 6-year testing period, weight gain across the 3 testing populations occured in a "stepwise fashion."  That is, individuals who remained sedentary gained the most weight (approximately 2.1 kg) while crossovers gained approximately 0.7 kg and exercisers gained the least at 0.4 kg on average.  Women in the true control group significantly gained weight and total body fat between baseline and year 6.

The investigators conclude that participation in resistance training is a viable option for postmenopausal women to manage body weight.  They purport that it should be one component of a regular comprehensive exercise program to improve overall health and prevent disease.

Source:
Medicine & Science in Sports & Exercise, July 2010, Vol. 42 Issue 7, pp. 1286-1295, "Resistance Training Predicts 6-yr Body Composition Change in Postmenopausal Women," Bea. J.W. et al.,.

Do you need to lose body fat?  Exercising four or more times per week can help you to achieve this goal, according to a study published in the November 2009 issue of The Journal of Strength and Conditioning Research.  Investigators evaluated the changes in body composition of 80 previously sedentary and deconditioned adults (ages 22-74 years) who began an exercise program based on the U.S. Surgeon General's guidelines to "exercise most days of the week."  The study was designed to specifically determine the role that frequency itself had on changing body composition.

The study lasted 8 weeks during which the subjects were instructed to exercise continuously for 30 minutes at a moderate-intensity (70% of their maximum heart rate), 4 times per week.  The participants exercised using either a 10-piece circuit training system or cardiovascular equipment.  Subjects were not prohibited from exercising more often than the prescribed amount.

The subjects' body composition values were determined before and after the study using a BodPod (air displacement plethysmography).  After completion of the study, the participants were divided into 4 categories based on their compliance to the frequency recommendation for exercise.  These categories included:

• Control group - individuals who chose not to exercise (20 subjects)
• Exercised less than 2 times per week (20 subjects)
• Exercised 2-3 times per week (20 subjects)
• Exercised 4 or more times per week (20 subjects)

With the exception of the control group (those who did no exercise), all groups lost body fat.  However, those subjects who exercised at least 4 times per week lost significantly more body fat than their counterparts (p=0.004).  The investigators conclude that the U.S. Surgeon General's recommendation to "exercise most days of the week" yields significant improvements in body composition for previously sedentary individuals.

Regular exercise is essential to improve overall health.  You can achieve favorable effects on body fat mass by following an exercise program that involves you to be physically active on at least four days per week.

Note:  Prior to beginning an exercise program or increasing the intensity level of an existing one, seek the approval of your physician, especially if you are at risk for or currently have chronic health conditions.


Resource:
J Strength Cond Res. 2009 Nov:23(8):2377-80 "Frequency of Exercise for Body Fat Loss: A Controlled, Cohort Study," Willis, F.B. et al,.

     Body composition refers to your body weight relative to the amount of muscle, bone, fat, organ and other vital tissues that make up that weight.  Much emphasis is placed on the amount of fat versus muscle tissue.  This is because optimal health is achieved through appropriate amounts of both.  Although the exact body fat percentage identifying risk has yet to be agreed upon, values that range between 10-22% for men and 20-32% for women are generally considered appropriate for health.

     Excess body fat is associated with heart disease, stroke, high blood pressure, type 2 diabetes, abnormal blood lipid (cholesterol) levels and the metabolic syndrome.  In addition to the amount of fat that you have, where it is located on your body is of concern.  Fat that is primarily located around your abdomen ("apple" shape) puts you at greater risk than if the fat is more concentrated around your hips and thighs ("pear" shape).

     There are different methods to estimate your body composition that vary in cost and complexity.  These include: 

• Skin-fold measurements in which various sites on your body are "pinched" by a caliper.  The values are put into a formula to determine percent body fat.  However, results are affected by skill level of the health professional conducting the measurements.
  
• Circumference measurements, such as the waist-to-hip ratio (WHR), involve measuring the girth of various body parts.  Different equations are used based on age and gender to compute the values.
  
• Bioelectrical impedance analysis (BIA) is a method in which the speed of a signal sent between electrodes placed on your feet and hands determines the amount of body fat.  A slower signal indicates greater amounts of fat because fat impedes the signal.  However, results can be skewed based on your state of hydration.
  
• Hydrostatic weighing (underwater weighing) is known as the "gold standard".  The amount of water you displace when submerged in a tank of water after blowing out all of the air in your lungs is measured.  The more water that is displaced the less fat you have.
  
• BOD POD is a fiberglass chamber in which you sit and the amount of air that is displaced by your body is measured to determine body composition.
  
• Dual energy X-ray absorpiometry (DXA) distinguishes the tissue densities of your body by exposing you to low amounts of radiation.
  

     Underwater weighing, the BOD POD, and DXA are typically used in university, hospital, and laboratory settings due to the cost and complexity of equipment and procedures required.  A simple way to estimate body fat percentage that many doctors use is the waist-to-hip ratio.  The WHR is the circumference of your waist at its narrowest point divided by the circumference of your hips at the largest point of your buttocks.  It provides insight into your body's distribution of fat.  If your WHR is high, it may indicate that you have a large amount of visceral fat, that is, fat deep within your abdomen.  An excess amount of visceral fat is associated with the chronic health conditions listed above.  

     The WHR's associated with a greater risk for disease based on age and gender are listed below.

Men:

• very high risk if under 20 years with a WHR that is at least 0.95
  
• very high risk if 60-69 years with a WHR that is at least 1.03
  
• high risk if 20-70 years with a WHR that is at least 0.89-0.99

Women: 

• very high risk if under 20 years with a WHR that is at least 0.86
  
• very high risk if 60-69 years with a WHR that is at least 0.90
  
• high risk if 20-70 years with a WHR that is at least 0.78-0.84

     Body Mass Index (BMI) is another means by which your physician may determine your risk for developing chronic health conditions.  The National Heart, Lung, and Blood Institute (NHLBI) defines BMI as "a measure of your weight relative to your height".  It is calculated by dividing body weight (in kilograms) by height (in meters) squared.  To easily determine your BMI, the NHLBI has a chart on their website that you can use www.nhlbi.nih.gov/guidelines/obesity/bmi_tbl.htm.  

     The NHLBI states that a BMI of 30 or more indicates obesity.  A BMI of 25-29.9 qualifies as being overweight.  Normal weight is a BMI of 18.5-24.9.  And, a BMI below 18.5 is underweight.  Health problems can occur at both extremes.  BMI's greater than 25 are typically associated with an increased risk for obesity-related health problems.  BMI's greater than 30 are associated with a higher incidence of high blood pressure, abnormal blood lipids, heart disease and death.

     There are limitations with calculating BMI.  It does not distinguish between fat and muscle weight.  If you have a muscular build, such as with athletes, it could classify you as being overweight or obese because muscle weighs more than fat.  Health risk tends to be underestimated in individuals who are older or who have lost muscle mass.

     You should consult your physician to determine what the appropriate weight is for you.  Your physician will give you advice on how to lose and maintain body weight in order to achieve optimum health.

Resources:

The National Heart, Lung, and Blood Institute www.nhlbi.nih.gov

ACSM's Guidelines for Exercise Testing and Prescription eight edition