Could someone briefly explain why these findinds occurred? Summarize the findings and from a biochemistry approach explain why they occurred?

Craig (1993) reviewed many of the exercise studies using fructose feedings and noted that fructose consumption prior to exercise does not cause an increase in either blood glucose or insulin. Although one study demonstrated a reduction in muscle glycogen use when fructose had been ingested prior to a 30 min exercise bout compared to feedings of glucose or water (Levine et al 1983), the glycogen-sparing effect of fructose ingestion was not confirmed in later studies using longer exercise bouts when glycogen could become more limiting (Hargreaves, 1987; Koivisto, 1985). This absence of effect on muscle glycogen occurred in spite of different glycemic and insulinemic patterns for the glucose versus fructose trials in the various studies. In addition, no performance benefit, as measured by time to exhaustion, was noted in most experiments for fructose compared to glucose. However, there may be some benefit to fructose ingestion prior to exercise when it is used in combination with other carbohydrate sources. For example, muscle glycogen sparing and performance enhancement were observed in athletes consuming a mixture of maltodextrin and fructose when compared to maltodextrin alone (Brouns et al 1989).

To summarize the studies that have used fructose feedings prior to exercise, blood glucose was maintained at higher levels during the initial period of exercise relative to high GI carbohydrates like glucose, but there were few reports of an ergogenic effect or a change in rate of muscle glycogen use. Because virtually all authors who fed fructose commented on the high incidence of gastrointestinal distress (due to slow fructose digestion), fructose alone is probably not practical in the concentrations required to provide sufficient energy; it may be useful as part of a mixture with other carbohydrates.

tanporcupine442

Could someone please briefly explain why the phenonema below is so?

Craig (1993) reviewed many of the exercise studies using fructose feedings and noted that fructose consumption prior to exercise does not cause an increase in either blood glucose or insulin. Although one study demonstrated a reduction in muscle glycogen use when fructose had been ingested prior to a 30 min exercise bout compared to feedings of glucose or water (Levine et al 1983), the glycogen-sparing effect of fructose ingestion was not confirmed in later studies using longer exercise bouts when glycogen could become more limiting (Hargreaves, 1987; Koivisto, 1985). This absence of effect on muscle glycogen occurred in spite of different glycemic and insulinemic patterns for the glucose versus fructose trials in the various studies. In addition, no performance benefit, as measured by time to exhaustion, was noted in most experiments for fructose compared to glucose. However, there may be some benefit to fructose ingestion prior to exercise when it is used in combination with other carbohydrate sources. For example, muscle glycogen sparing and performance enhancement were observed in athletes consuming a mixture of maltodextrin and fructose when compared to maltodextrin alone (Brouns et al 1989).

To summarize the studies that have used fructose feedings prior to exercise, blood glucose was maintained at higher levels during the initial period of exercise relative to high GI carbohydrates like glucose, but there were few reports of an ergogenic effect or a change in rate of muscle glycogen use. Because virtually all authors who fed fructose commented on the high incidence of gastrointestinal distress (due to slow fructose digestion), fructose alone is probably not practical in the concentrations required to provide sufficient energy; it may be useful as part of a mixture with other carbohydrates.

maroonelephant29

QUESTION 1

Before undertaking an exercise or nutrition program, whatpreliminary steps should be taken?

		Choose an expensive activity; that way you know you've investedmoney in it and be more likely to stay with it.
		Go to an exercise physiologist who can teach you how the bodyworks.
		Choose an enjoyable activity that you know you will stay withwhether you're alone or in a group.
		Get an exercise stress test from a sports medicine doctor who isalso knowledgeable in nutrition.

QUESTION 2

The most important component(s) of exercise from a health andlongevity standpoint is(are)

		the intensity and duration of the activity.
		the duration and frequency of the activity.
		the frequency and regularity of the activity.
		the warm-up and cool-down periods.

QUESTION 3

Among the physiological benefits of regular exercise, which ofthe following can occur?

		Regular exercise will inhibit the blood chemistry responsiblefor the "good" cholesterol.
		Regular exercise can be a way to improve mood and relievedepression.
		Regular exercise has been shown to increase the need for"energizers."
		Regular exercise decreases blood flow to the brain, thereforeactivating endorphins, natural tranquilizers.

QUESTION 4

By eating a high carbohydrate diet the day before any athleticevent,

		muscles will have adequate fuel, i.e., glycogen for thecompetition.
		athletes can eat more protein the day of the competition.
		less water will be needed the day of the competition sincecarbohydrates are high in water.
		all of these.

QUESTION 5

A person with high blood cholesterol should considerparticipating in an aerobic exercise program such as walking orjogging because aerobic exercise

		will raise HDL ("good") cholesterol after a period of trainingand decrease the risk for heart disease.
		will cause a sudden increase in the heart rate to near maximallevels which lowers the "bad" cholesterol.
		forces more LDL ("bad") cholesterol out of the body throughwaste elimination.
		keeps the blood circulating faster, even at rest, thereforecauses a decrease in total blood cholesterol.

QUESTION 6

For most athletes who are well-nourished, nutrition supplementssuch as protein powders and vitamin pills

		dramatically improve performance.
		improve performance only moderately.
		do not significantly improve performance.
		seem to cause a decrease in performance.

QUESTION 7

In addition to being able to exercise at work, employees whohave access to a Wellness program and fitness facility at the jobsite

		is more likely to make positive changes in lifestyle.
		has less absenteeism from work.
		becomes more educated in health issues.
		all of these.

QUESTION 8

The general recommendation to support activity is to eat adiet

		high in protein and low in fat.
		low in protein and high in carbohydrate.
		high in carbohydrate and low in fat.
		high in carbohydrate and high in protein.

QUESTION 9

Walking is considered the best form of exercise because it

		is not expensive.
		promotes cardiovascular endurance.
		is easy to perform.
		all of these.

QUESTION 10

Exercise and nutrition are important components of a soundprogram for physically challenged people because they

are investments in good physical health.

help support a positive mental health.

help people face the challenges of life and achieve dreams.

all of these.

ivoryhornet198

Kinesiology 3339A/B Lecture 15: Exercise Nutrition - Lecture 15

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		are investments in good physical health.
		help support a positive mental health.
		help people face the challenges of life and achieve dreams.
		all of these.