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Wednesday, June 23, 2010

Is Elliptical Training as Good as Running for Improving Fitness?

Elliptical trainers have become very popular in gyms as well as in the home. Their popularity is due to a lack of impact on the body while providing resistance to both the lower and upper body musculature. The movement pattern looks similar to running but does not involve pounding of the feet on the ground. An added advantage is the relative silence of an elliptical device compared to a treadmill, which produces considerable noise from foot strikes and its motor.

An important question is whether the elliptical trainer provides as good an aerobic workout as a treadmill or running outside. A study by Brown et al. in the Journal of Strength and Conditioning Research (volume 24, number 6, pp. 1643-1649, 2010) was designed to answer that question.

Experimental Procedure
9 male and 9 female college-aged subjects worked out for 15 minutes on different days on both a treadmill and an elliptical trainer at a difficulty level they self-selected as “somewhat hard.” The subjects were instrumented to collect information on their rate of oxygen utilization, pulse rate and other relevant variables.

The only statistically significant differences between exercise on the elliptical machine and the treadmill were that the elliptical machine produced higher:
  • heart rate
  • percentage of maximal rate of oxygen utilization
  • Ratio of carbon-dioxide produced to oxygen used
However, there were no significant differences in total energy expenditure or total oxygen consumption.

Bottom Line
The similarities between the responses to exercise on the elliptical trainer and treadmill were far more important than their differences. They both produced very similar aerobic stimulus to the body when the subjects worked out at a moderate level of difficulty, which is typical. Therefore, for general health, one can use an elliptical trainer with confidence. However, since running is a very basic human activity that is essential for sports and reacting to emergencies, run training is still generally more useful. Someone who trains exclusively on an elliptical machine and reaches a high level of fitness will not perform as well when faced with a running challenge, and muscle soreness will surely result. Yet, elliptical training is a good way to maintain cardio-respiratory function for injured athletes and others who cannot tolerate lower body impact. It can also provide variety in training for those who run regularly.

Tuesday, June 22, 2010

How to Avoid Weightlifting-Related Shoulder Injuries

Terms used in this article:
  • Rotator cuff: Muscles (supraspinatus, infraspinatus, teres minor, subscapularis) that stabilize the shoulder joint and rotate the arm at the shoulder
  • Internal shoulder rotation: Standing with your upper arm against your torso with your elbow at a right angle, rotate your upper arm inward until your hand touches your abdomen.
  • External shoulder rotation: From the position you just attained by internally rotating your shoulder, rotate your upper arm outward so that your hand moves away from your abdomen, as you would when throwing a Frisbee.
  • Trapezius muscle: Extends from the back of your head and neck down your central upper back and serves to raise the shoulders and draw them backwards.
  • Range of motion: The number of degrees through which a joint can be rotated.

A recent article by Kolber et al. in the Journal of Strength and Conditioning Research (Vol 24, no 6, pp. 1696-1704, 2010) reviewed existing scientific research articles on shoulder injuries brought on by weightlifting. It noted that 25-35% of people who engage in resistance training sustain an injury severe enough to require medical attention and that 36% of such injuries are to the shoulder. The vulnerability of the shoulder is related to the high number of exercises that involve the shoulder, the great stresses the exercises place on the shoulder, and the unfavorable positions in which some exercises place the shoulder. In addition, many lifters do not warm up properly, select a balanced set of exercises, use proper lifting technique, or modify/eliminate exercises that cause pain. Major muscles are frequently worked to the exclusion of minor ones, leading to muscle imbalances. Shoulder muscles commonly injured include the pectoralis major, biceps, deltoid and rotator cuff group.

The Most Common Signs of Shoulder-Dysfunction Among Weightlifters:
  • Reduced internal shoulder rotation range of motion
  • Excessive external shoulder rotation range of motion
  • Underdeveloped external rotation strength relative to internal rotation strength
  • Underdeveloped external rotation strength relative to arm abduction (raising) strength
  • Underdeveloped lower trapezius strength relative to upper trapezius strength
  • Instability of the anterior (front) shoulder
  • Tightness of the posterior (rear) shoulder
Common Pain-Producing Exercises
The following exercises in which the upper arm is raised to the side and parallel to the floor while the forearm is vertical put the shoulder in a fully externally rotated position and are considered hazardous:
  • Behind the neck pull-down
  • Behind the neck overhead press
  • Overhead stack machine press in which the hands move rearward as the weight is lifted
Other exercises, although generally safe, also associated with shoulder pain:
  • Bench press
  • Incline chest fly
  • Supine chest fly
  • Dip
  • Biceps curl
The following may help to prevent weightlifting-related shoulder injury:
  • Discontinue any exercise that causes pain.
  • If an exercise hurts, try variations that do not hurt (e.g. bench press with rolled up towel on chest to limit movement).
  • Balance every push exercise with a pull exercise in the opposite direction.
  • Balance exercises involving major body movements (e.g. bench press, pull-down) with those that stabilize and rotate the shoulder.
  • Exercises that strengthen external shoulder rotation are particularly important (e.g. do the external rotation movement described above, resisted by weight stack cable or elastic band).
  • Do strength exercises for the lower trapezius (e.g. rowing motions with elbows high and shoulders drawn fully back).
  • Do flexibility exercises to increase internal shoulder rotation.
  • Do flexibility exercises to stretch the rear shoulder (e.g. Stand with upper arm parallel to the ground. Grip elbow with other hand and pull arm horizontally across the chest).

Friday, June 4, 2010

Should You Skip Breakfast to Burn More Fat During a Workout?

An Associated Press article suggesting that, because skipping breakfast before a workout burns more fat, such a practice may be effective for body fat loss. Yet, the study on which the article is based provides absolutely no evidence that such a practice would result in a stable loss of body fat. Sure, if your body is depleted of stored carbohydrates in the form of muscle and liver glycogen, you will burn more fat during exercise. However, a close look at the article reveals that the fat burned is in the muscle, and not around the waist or other parts of the body where people generally want to lose fat. Thus, exercising in a fasted state merely depletes intramuscular fat that is replenished upon eating. So there is no net body fat loss unless one consumes fewer calories than are used, which requires dietary control. So we can’t escape from the truism that the only way to lose weight is to burn more calories than you take in.

The following are additional reasons not to exercise in a fasted state:
  • You will feel less energetic and more lethargic
  • The quality of your workout will diminish
  • Your motivation to exercise will be reduced
  • You will cannibalize muscle to convert protein into needed carbohydrates
The only advantage to running in a fasted state might be for long-distance runners who wish to train their bodies to preferentially burn fat, thereby sparing muscle and liver glycogen to avoid “hitting the wall” late in a race. However, training with long-distance runs accomplish the same goal.

Wednesday, June 2, 2010

Caffeine May Interfere With Muscle Building

An online article in the Journal of Sports Science and Medicine by Wu and Lin (vol 9, pp 262-269, 2010) indicates that going heavy on the caffeine before resistance training may be counterproductive.

Experimental method
Ten men performed a workout consisting of 3 sets of 8 exercises. Each set consisted of 10 repetitions of 75% of the weight that could be lifted only once. On one day, the workout was performed an hour after caffeine ingestion and on another day an hour after ingesting a non-caffeinated placebo. The amount of caffeine was 6 mg/kg or about 475 mg for a 175 lb man. That’s about the amount of caffeine in one-and-a-half 16 oz Starbucks Grande coffees or four-and-a-half 8 oz cups of home-brewed coffee. Blood was analyzed at various times for levels of insulin, testosterone, cortisol, growth hormone, glucose, free fatty acid and lactic acid.

As has been observed in previous studies, blood levels of free fatty acids were higher in those who ingested caffeine than in those who did not. That is why caffeine is considered an ergogenic aid (performance enhancer) for endurance sports. Long distance runners often take in caffeine to promote the burning of fats in preference to carbohydrates, allowing the limited store of carbohydrates in the muscle and liver to last longer, sparing the athlete from “hitting the wall’ later in the race.

A result not noted in previous studies was that blood concentration of human growth hormone (HGH) was significantly lower when the subjects had previously ingested caffeine than when they hadn‘t. Since HGH is a muscle-building hormone, caffeine ingestion prior to resistance training can be considered counterproductive.

There were no significant differences in blood levels of insulin, testosterone and cortisol between caffeine and no-caffeine conditions.

Bottom Line
It appears prudent to avoid caffeine consumption for at least 3 hours prior to a resistance training session in order to maximize results. Since the time it take for the body to rid itself of half of ingested caffeine is approximately 5 hours in healthy adults, then excessive caffeine consumption is not recommended, even several hours before a workout.

Limiting Your Fruit and Vegetable Pesticide Exposure

The Environmental Working Group, a nonprofit organization whose purpose is to promote public health, reviewed nearly 100,000 reports on fruit and vegetable pesticide residue from the U.S. Food and Drug Administration and the Department of Agriculture. After being washed with a USDA high-pressure water system, many of the fruits and vegetables still contained high pesticide residues. The following were the worst.
  • Celery
  • Peaches
  • Strawberries
  • Apples
  • Domestic blueberries
  • Nectarines
  • Sweet bell peppers
  • Spinach, kale and collard greens
  • Cherries
  • Potatoes
  • Imported grapes
  • Lettuce
 In contrast, the following were found to have little or no pesticide residue.
  • Onions
  • Avocados
  • Sweet corn
  • Pineapples
  • Mango
  • Sweet peas
  • Asparagus
  • Kiwi fruit
  • Cabbage
  • Eggplant
  • Cantaloupe
  • Watermelon
  • Grapefruit
  • Sweet potatoes
  • Sweet onions
Bottom Line
Obviously, buying organic fruit and vegetables is the simplest and most direct way to avoid pesticide exposure. Unfortunately, organic produce is usually a lot more expensive than the non-organic variety and most people balk at the price difference. A reasonable compromise is to limit consumption of the most pesticide-tainted fruits and vegetables and preferably buy them in organic form, while buying other fruits and vegetables in non-organic form. The Environmental Working Group states that switching to the organic version of just the produce from the worst-offender list would reduce total dietary pesticide consumption by 80%.