Sports Nutrition And Exercise (Video)
Nutrition and Exercise: Healthy Balance for a Healthy Heart
What is the resting metabolic rate? How is it measured? Why is it beneficial to know?
The resting metabolic rate (RMR) or basal metabolic rate is the amount of energy required to carry out the body’s basic functions of respiration, circulation, and thermal regulation during a 24-hour period while in a resting state. Several factors influence resting metabolic rate, including gender, height, weight, and percentage of lean muscle mass.
Resting metabolic rate can be a beneficial tool for an athlete in helping to regulate and maintain an ideal body weight. The resting metabolic rate ranges between 60% and 65% of an individual’s total energy expenditure, and knowing it can be useful in helping athletes to achieve weight goals and optimize athletic performance.
The resting metabolic rate is usually measured using a sophisticated, noninvasive breath analysis technique. The procedure takes approximately 30 minutes to complete and is designed to measure an individual’s oxygen consumption to carbon dioxide output. The ratio of oxygen consumed to carbon dioxide produced in a relaxed, resting state will help to determine how much carbohydrate, fat, and total energy (calories) an individual is burning at rest.
To help ensure breath analysis accuracy, the clinician will try to control the following individual variables:
1. Avoid eating approximately 2 hours prior to testing.
2. Avoid exercise the day before and day of the test.
3. Avoid ingesting stimulant-based products such as caffeine, nicotine, or certain medications or supplements on test day, as these products have the potential to influence metabolic rate, thus resulting in inaccurate data.
Because it is not feasible for all athletes to get a resting metabolic rate test, it can also be estimated using a simple formula that requires an individual’s weight, height, age, and activity level. Formulas are only estimates and can have error rates of between 100 and 200 calories per day compared with breath analysis techniques.
One of the most accurate energy equations is the Mifflin St. Jeor:
Female: (10 × weight) + (6.25 × height) – (5 × age) – 161
Male: (10 × weight) + (6.25 × height) – (5 × age) + 5
Weight in kilograms (1 kilogram = 2.2 pounds)
Height in centimeters (1 inch = 2.54 centimeters)
Activity Factors:
1.200 = sedentary (little or no exercise)
1.375 = lightly active (light exercise/sports 1–3 days/week)
1.550 = moderately active (moderate exercise/sports 3–5 days/week)
1.725 = very active (hard exercise/sports 6–7 days a week)
1.900 = extra active (very hard exercise/sports and physical job)
Case Study
A 21-year-old, 6-foot (72 inch), 175-pound female collegiate basketball player wants to know her resting metabolic rate. She does not have access to the breath analysis technique but is advised to use the Mifflin St. Jeor equation as a reliable substitute.
Female: (10 × weight) + (6.25 × height) – (5 × age) – 161
Weight in kilograms (1 kilogram = 2.2 pounds) = 175/2.2 = 79.5 kilograms
Height in centimeters (1 inch = 2.54 centimeters) = 72 × 2.54 = 182.9 centimeters
(10 × 79.5) + (6.25 × 182.9) – (5 × 21) – 161 = 1,672 calories per day without activity level factor
1,672 calories per day × 1.725 = 2,884 calories per day
1,672 calories per day × 1.900 = 3,176 calories per day
The recommend caloric intake for this athlete is 2,884 – 3,176 calories per day
Terms:
Resting metabolic rate (RMR) – The minimum amount of energy required to meet the energy demands of the body while at rest. The resting metabolic rate is typically measured instead of BMR because it is only slightly higher than BMR and is determined under less rigorous conditions.
Basal metabolic rate – The minimum amount of energy required to sustain life in the waking state. The basal metabolic rate is usually measured in the laboratory under very rigorous conditions.
What is the Wingate power test? Why is it important? How is it measured?
The Wingate power test was developed during the 1970s at the Department of Research and Sports Medicine of the Wingate Institute for Physical Education and Sport in Israel. Since its introduction, the test has become the gold standard around the world for assessing muscle power, muscle endurance, and muscle fatigability.
The test has been used as a reproducible standardized method to analyze physiological responses to high-intensity exercise. The Wingate power test is an excellent method to evaluate an athlete’s peak power, mean (average) power, and muscle fatigability. A cyclist climbing a steep hill during a race, for example, would require maximal or near maximal force in order to be able to advance ahead of other competitors. Training for maximum power output, in this case, could make the difference between this cyclist being in the middle or at the head of the pack.
The Wingate power test for the lower torso is conducted on a stationary bike ergo meter that measures power output in either watts or Newton’s. After a thorough warm-up, the athlete is given the command “go,” at which point the athlete cycles at maximum effort for the duration of 30 seconds. The highest 3 to 5 seconds of power output will be used to determine peak power, and the average 30-second power output will be used to determine mean power. Muscle fatigue can be graphed demonstrating percentage decreases in muscle power output over the 30 seconds. After 15 to 20 minutes of complete recovery, a second test may be administered, as needed. The exercise physiologist graphs the data to help identify strengths and potential deficiencies in the athlete’s power output. This information can then be used by the exercise physiologist to help design a training program for improving the athlete’s peak and mean power output while reducing muscle fatigability. A Wingate power test is also available for evaluating upper-torso power-particularly useful for athletes who participate in rowing, swimming, and boxing events.
Term:
Wingate power test – The gold standard to assess muscle power, muscle endurance, and muscle fatigability.
What is the running economy test? How is it measured? Why is it important?
The running economy test is a laboratory assessment that is conducted by an experienced exercise physiologist to determine the efficiency of a runner’s muscles, joints, and pulmonary system (lungs). The test requires an athlete to run on a treadmill set at a standard speed and elevation while attached to a metabolic cart that measures the amount of oxygen the athlete consumes at a pre-determined workload based on the athlete’s body mass. The less oxygen an athlete requires during the test, the more efficient he or she is with his or her running and the less energy he or she will expend at that effort.
A running economy test is an excellent means of determining how much energy an athlete expends while exercising at a specific workload. Research has demonstrated that economical runners generally outperform less economical runners with similar physical and physiological attributes, as they tend to consume less oxygen for an identical amount of work. In other words, at a given speed of running, economical runners may not need to work as hard or use as much energy, which enables them to train and compete with greater intensity.
Running economy is measured on a treadmill. The athlete is attached to a metabolic cart and will run at a predetermined workload based on the athlete’s body mass.
The test is usually conducted in a laboratory setting by an experienced exercise physiologist. Running economy can vary between 1% and 4% from one day to the next and can be significantly improved with a well-designed exercise program involving strength development, sprinting, and over speed training
Case Study
Sam, a marathon runner with 7 years of experience, has been sent by his coach to the performance laboratory for a running economy test. His coach believes that Sam is having difficulty with his running efficiency and believes that it can be improved. Sam’s running economy test results confirmed that he does indeed have a slight deficit in his running efficiency.
The exercise physiologist designed a 12-week sports specific program that involved strength, sprint, and over speed training. The second test, conducted 12 weeks later, revealed a 5% improvement in Sam’s overall running economy. This improvement resulted in a 15-second per mile decrease in Sam’s marathon time. His minute per mile pace improved from 6:25 minutes per mile pace to a 6:10-minute per mile pace, a significant improvement.
Term:
Running economy test – A laboratory assessment to determine the efficiency of a runner’s muscles, joints, and pulmonary system (lungs).
