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Friday, April 29, 2011

Soy Products Have a Negative Effect on Masculinity

Because it is a relatively inexpensive source of protein, soy is widely used to fortify many high-protein foods such as bars, cereals and shakes. However, as detailed on our website, the estrogen-like qualities of soy proteins (isoflavones) have a negative effect on masculinity.

A recent study by Wada et al. in the American Journal of Epidemiology (vol. 173, no. 9, pp. 998-1003, 2011) indicates that such demasculinizing effects can begin very early. The researchers collected dietary histories and urinary testosterone levels from 230 Japanese boys aged 3-6 years. When the boys were divided into 4 groups based on the quantity of soy they ate, the group that consumed the least soy had a notably mean higher testosterone level than the other 3 groups. The same was true when the grouping was made based on isoflavone consumption.

The American Academy of Pediatrics, but not the U.S. government, has recommended that infants who cannot be breastfed be nourished with formula based on cow milk rather than soy. Also, several countries including Israel, France, New Zealand, and Australia have officially recommended against soy-based baby formula. While the U.S. has made no such official recommendation, parents here would do best to avoid soy-based infant formula as well as soy-containing foods for their older children.

Bottom Line
Men should carefully read nutrition labels and avoid foods containing soy or isolated soy protein. Preferable sources of protein include fish and lean meats, low-fat dairy products, and eggs in moderation. Acceptable protein supplements include whey protein and casein, both derived from milk. Some men avoid milk because they believe they are intolerant of lactose (milk sugar). Yet many of these men are not actually lactose intolerant. For those who really are, there are many alternatives. Whey protein and casein do not contain lactose, and have shown in studies to be very effective for muscle building. Most cheeses are made up mainly of protein and fat, with very little lactose, but should be eaten in moderation because of the high saturated fat and cholesterol content. Milk products should be of the low-fat or non-fat varieties to limit saturated fat and cholesterol. Lactose-free milk is also available in most supermarkets.

Tuesday, April 12, 2011

Our Changing Eating Patterns

The U.S. Department of Agriculture recently published information on the sources of our daily caloric intake between 1970 and 2008, a time period in which our daily caloric consumption increased by 23.2% from 2,169 cals to 2,672 cals, and rates of overweight and obesity have risen sharply. An interactive graphic was created from the data that allows users to scroll along a time-line to see how the amount of daily calories in each food category has changed over time. The following are the percentage changes in calories coming from each food category:

meat, eggs, and nuts: +4.1%
fruit:                         +22.9%
added fat:                 +56.3%
dairy:                          -3.7%
grains:                      +44.7%
vegetables                   -2.4%
added sugar              +14.2%

Some Observations on the Data

In Terms of Absolute Calories
  • The biggest contributors by far to our increased daily caloric intake are added fat (231 cals) and grains (193 cals).
  • Much more modest contributors to our increased daily caloric intake are added sugar (57 cals), meat/eggs/nuts (19 cals), and fruit (16 calories).
  • Our daily consumption of dairy actually decreased by 10 calories and of vegetables by 3 calories.
In Terms of Percentage of Daily Calories
  • The only foods that increased as percentages of our diet from 1970 to 2008 are added fats (from 18.9% to 24.0% of daily calories) and grains (from 19.9 % to 23.4% of daily calories).
  • Caloric consumption from fruit was steady at 3.2 % of calories.
  • All other foods declined as percentages of our daily calories including meat/nuts/eggs (from 21.3% to 18.0% of daily calories), dairy (from 12.3% to 9.6% of daily calories), added sugar (from 18.5% to 17.2% of daily calories), and vegetables (from 5.8% to 4.6% of daily calories).
Bottom Line
The greatest contributors to our increase in caloric consumption are grains and added fat. While we have increased our intake of all other foods except vegetables, grains and fat together account for 84% of our increase in caloric consumption and should therefore be the prime focus of cutting back calories. This makes it clear that the low-fat and low-carb diets are both missing something because the intake of both must be reduced. Any diet that emphasizes what you eat rather than how much you eat is bound to fail. Overweight and obese people who seek to attain a healthy body weight must face the reality that total intake must be lessened. Focusing on eating both fewer grain-based foods and fewer added fats is a good start.

Friday, April 8, 2011

Can Video Games Improve Physical Fitness?

With the development of video game devices that detect body motions of players and use those motions to control games, the opportunity for turning the formerly sedentary activity of video gaming into physically active fun has greatly expanded. However, it is only recently that the exercise stimulus of such games has been scientifically evaluated. One such study, by Worley, Rogers, and Kraemer was recently reported in the Journal of Strength and Conditioning Research (vol. 25, no. 3, pp. 689-693, 2011).

Experimental Procedure
8 young women averaging 22 years of age were first tested for the maximal rate at which their bodies could process oxygen (VO2max). Then they played 2 different Nintendo Wii Fit video games (Hula and Step) at the beginner and intermediate levels for 10 minutes each. During each game session, each subject was connected to a metabolic cart that measured the rate of oxygen consumption.

The percentage of VO2max elicited during the video games ranged from 30.6% for the beginner level Step game to 39.4% for the intermediate level Hula game. These levels respectively corresponded to walking speeds of 2.5 mph and 3.6 mph, categorized as mild to moderate exercise.

Bottom Line
Video games that require physical activity have excellent potential for getting people who would not ordinarily exercise to do so. Nintendo’s Wii system involves a controller that is held in the hand and picks up movements using accelerometers. The XBOX game with the Kinect accessory is revolutionary in that it senses whole body movements without anything held in the hand or attached to the body. While the games in this study only elicited mild to moderate levels of exercise, the advanced game levels were not tested, probably because they require a lot of practice. Thus, the potential for higher exercise levels is certainly there. These games are a great way of getting people who are not attracted to sports or typical exercise routines but who like video games to become more physically active.

Monday, April 4, 2011

Effectiveness of Different Kinds of Strength Training Periodization

Periodization of strength training entails changing over time the weight handled in each exercise along with the number of repetitions per set. When the weight used is higher, the number of repetitions is lower and when the weight used is lower, the number of repetitions is higher. It is widely agreed among strength and conditioning professionals that periodized strength training is more effective than non-periodized training.

There are various versions of strength training periodization, including:
  • Traditional periodization - The trainee starts with relative light weights and high repetitions, and over a period of several weeks, increases the amount of weight lifted while decreasing the number of repetitions. For example, the trainee might begin by doing 10 repetitions per set with 60% of the maximum weight that can be lifted for a single repetition and progress to 4 repetitions with 80% of the max weight.
  • Daily Undulating Periodization - On different days, the trainee uses a different combination of weights and repetitions. A sample schedule might be medium weight and medium reps on Monday, light weight and high reps on Wednesday, and heavy weight and low reps on Friday.
  • Weekly Undulating Periodization - Weight and reps fluctuate from week to week. A sample schedule might be low weight and high reps on week 1, medium weight and medium reps on week 2, and high weight and low reps on week 3, with this 3-week pattern repeating several times.
A recent study by Apel, Lacey, and Kell in the Journal of Strength and Conditioning Research (vol. 25, no. 3, pp. 694-703, 2011) sought to determine the relative effectiveness of traditional vs. weekly undulating periodization.

Experimental Procedure
Forty-two young, physically active men were divided into three groups of 14 that trained for 12 weeks as follows:
  • Control group - Performed no strength training
  • Traditional periodization (TP) - Increased the resistance in a fairly linear manner from 57% of max the first week to 80% of max the final week.
  • Weekly Undulating Periodization (WUP) - Started at 57% of max, but increased resistance over 3 weeks before reducing weight close to where it started and increasing it back again over 3 weeks. This was done over 3 cycles in which both the starting and ending weight for each 3-week cycle became greater than for the previous 3-week cycle, ending at 78% of max.
There were 15 different exercises selected to work the entire body. The exercises used, rest time, total exercise volume and average percent of maximum weight used were the same in both groups. There were 3 training sessions per week for the first 2 weeks and 4 per week for the remaining weeks, in which half the exercises were performed 2 days per week (e.g. Mon. and Thu.) and the other half on 2 other days per week (e.g. Tue. and Fri).

  • Both periodized training groups increased significantly in strength, while the control group did not.
  • Increases in back squat strength were significantly greater for the TP group (54%) than for the WUP group (34%).
  • Increases in bench press strength were significantly greater for the TP group (24%) than for the WUP group (19%).
  • Increases in pull-down strength were significantly greater for the TP group (29%) than for the WUP group (19%).
  • Increases in dumbbell shoulder press strength were significantly greater for the TP group (48%) than for the WUP group (36%).
  • Increases in leg extension strength were greater for the TP group (39%) than for the WUP group (27%), although the between-group difference did not reach statistical significance.
  • There was more muscle soreness and fatigue reported among the WUD group, which may have hindered training progress.
Bottom Line
For this group of recreationally active males, traditional periodization produced superior results to weekly undulating periodization. The between-group differences were great enough to be meaningful.