Why Do Some Get Fitter Than Others? Part 2

Continuing from the last post….

Next, the scientists examined the animals’ hearts. Normally the left ventricle of the heart in animals and people becomes larger and thus able to contract more forcefully after endurance training. The high-responding rats showed these structural changes in their left ventricles, evidence that they were developing athletes’ hearts. The other rats showed almost no physiological adaptations; it looked like they had not exercised at all.

Ulrik Wisloff, a professor at the Norwegian University of Science and Technology explained that this is likely why the animals lost fitness training. If hearts don’t adapt to the demands of exercise, workouts will not strengthen their bodies.

While looking at the gene expression in the animals’ heart cells, scientists found over 360 genes operating differently in the two different groups. These genes direct processes that should increase the size of the heart but were not working as effectively in the animals that were bred to be resistant to exercise.  Humans have the same genes in our heart cells.  It is impossible to know if our genes respond exactly the same as the genes of rats but it’s possible that they may. However, the interplay of genes and exercise is extremely complex. We are still only in the early stages of understanding effects of environment, heredity, nutrition and even psychology on rates of exercise.

We should monitor our body’s response to exercise. If after months of training and someone is still not able to run any farther than he or she could before, it is time to change the workout. It is likely that the genes that control the body’s response to that activity are different than those involved in responses to aerobic exercise.

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Why Do Some Get Fitter Than Others?

Scientists are puzzled as to why some people’s bodies respond better to working out than others. According to some studies, genetics must be involved because response to exercise seems to run in families. But which genes are involved? And how exactly do these genes increase or stunt the body’s response?

The NY Times writes about a recent study in rats. In the study, rats with a certain set of genes responded vigorously to exercise; they became much more fit after a few weeks of running. Rats with other genes gained little cardiovascular benefit from the same exercise program; their heart muscles didn’t react as expected.

People who exercise diligently but see no results should consider revising their workout routine. The range of response to exercise can be extremely large. A study published in March examined overweight men and women who enrolled in five months of endurance or weight training. By the end, the men and women were, on average, 8% stronger or more aerobically fit. But 13% of those in the endurance group lost aerobic capacity and 30% of those in the strength-training group were weaker.

Another rodent study conducted at the University of Michigan and the Norwegian University of Science and Technology, scientists created two strains of rats that would or would not respond well to working out. First, they had rats run for several weeks to see how much distance the animals added before tiring out. They also noted how well they were adapting to the workouts. They found that the males who added the most mileage were bred with females who responded similarly. The animals that added the fewest miles to their runs mated to one another.

Several generations later, the scientists had rats that should be significantly high or significantly low responders to exercise. The first part of the experiment supported this. The two different types of rats were set on treadmills with identical workouts. After a two month training program, there was a significant difference with the types of rats. Rats there were bred to respond well to exercise training increased the distance they could run before tiring by 40%. The other rats lost about 2% of their endurance during the training.

To be continued…

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Popular Fruits and Vegetables Ranked by Nutritional Value

Jonathan Globerman

Many fruits and vegetables can help prevent chronic illnesses like cardiovascular disease and certain types of cancers. Scientists call these kinds of fruits and vegetables “powerhouse fruits and vegetables,” or PFV’s.

Dietary researcher Jennifer Di Noia, Ph.D., of William Paterson University decided to quantify the nutritional benefits of some of the most popular fruits and vegetables. Of the 47 foods she tested, only 41 were good enough for her to deem them “powerhouse” foods. Her findings were then published in Preventing Chronic Disease, a peer-reviewed journal managed by the National Center for Chronic Disease Prevention and Health Promotion.

PFV’s have previously been described as green leafy, yellow/orange, citrus, and cruciferous items, so Di Noia decided to look at the densities of key nutrients in these kinds of fruits and vegetables.

The point system she devised is a nutrients-to-calories ratio. Using guidelines provided by the Food and Agriculture Organization of the United Nations and Institute of Medicine, she looked at nutrients considered important to public health, including potassium, fiber, protein, calcium, iron, thiamin, riboflavin, niacin, folate, and zinc, as well as vitamins A, B6, B12, C, D, E, and K. Basically, the higher ranking the food, the more nutrients-per-calories it provides.

A few key foods notably not included in the study were raspberries, tangerines, cranberries, garlic, onions, and blueberries. Though most people would expect to see these somewhere on the list, Di Noia explains that they didn’t make the cut because they were not rich enough sources of the nutrients she was looking at. These popular foods get their health benefits from phytochemicals, which she was not measuring for this study.

The goal of this study is to provide a guide for consumers to make sure they are focusing on the most nutrient rich foods possible when shopping. Here is a complete list of the powerhouse fruits and vegetables in the study with their corresponding scores:

Watercress: 100.00

Chinese cabbage: 91.99

Chard: 89.27

Beet green: 87.08

Spinach: 86.43

Chicory: 73.36

Leaf lettuce: 70.73

Parsley: 65.59

Romaine lettuce: 63.48

Collard green: 62.49

Turnip green: 62.12

Mustard green: 61.39

Endive: 60.44

Chive: 54.80

Kale: 49.07

Dandelion green: 46.34

Red pepper: 41.26

Arugula: 37.65

Broccoli: 34.89

Pumpkin: 33.82

Brussels sprout: 32.23

Scallion: 27.35

Kohlrabi: 25.92

Cauliflower: 25.13

Cabbage: 24.51

Carrot: 22.60

Tomato: 20.37

Lemon: 18.72

Iceberg lettuce: 18.28

Strawberry: 17.59

Radish: 16.91

Winter squash (all varieties): 13.89

Orange: 12.91

Lime: 12.23

Grapefruit (pink and red): 11.64

Rutabaga: 11.58

Turnip: 11.43

Blackberry: 11.39

Leek: 10.69

Sweet potato: 10.51

Grapefruit (white): 10.47

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