Factors Affecting Performance

Question 1

2 Sites of Fatigue

Answer 1

• central
• peripheral

(or both)

Question 2

Peripheral Fatigue
:Excitation Contraction Coupling:
2 Hypotheses

Answer 2

• depletion hypothesis

- accumulation hypothesis

Question 3

2 Factors Affecting Performance

Answer 3

• fatigue

- Muscle recruitment

Question 4

Fatigue

Answer 4

inability to continue a specified task, which is reversible with rest

Question 5

Fatigue depends on:

Answer 5

• Type of exercise performed
• muscle fiber types involved
• pt’s fitness and nutritional status

Question 6

Mechanisms of Central Fatigue

Answer 6

• decr functional motor units or decreased frequency of firing
• inhibitory input to neurons in brain from muscle afferents
• psychological (motivation)
• serotonin

Question 7

Components of Peripheral Fatigue

Answer 7

• neuromuscular junction
• muscle cell membrane
• excitation contraction coupling (primary site of fatigue)

Question 8

Order of Muscle Recruitment

Answer 8

Type I, IIa, IIx

Question 9

Type I fibers

Answer 9

• recruited first
• provide tension to about 40%VO2 max
• aerobic metabolism

Question 10

Type IIa

Answer 10

• recruitment if O2 not available to utilize type I
• recruited if intensity reaches 40-75% VO2 Max
• aerobic and anaerobic metabolism

Question 11

Type IIx

Answer 11

• recruited if O2 delivery not sufficient for type I & IIa fibers
• recruited at ~75% VO2 max
• anaerobic glycolysis

Question 12

High H+ Concentration can cause:

Answer 12

• decr force/crossbridge
• decr force for given Ca++ concentration
• inhib Ca++ release from SR
• Disruption of Na-K pump
• inhibition of PFK

Question 13

Depletion Hypothesis

Answer 13

depletion of ATP, PC, & Glycogen

Question 14

Accumulation Hypothesis

Answer 14

-accumulation of ammonia, phosphate, lactate, H+

Question 15

Long Term Activities

Answer 15

• 1-4 hours
• ability of liver & muscle to provide glucose

(change glycogen–>glucose)

Question 16

Intermediate Length Activities

Answer 16

• 21-60 min
• % VO2 max needed to maintain required VO2

(heat & dehydration a component too)

Question 17

Moderate Length Activities

Answer 17

• 3-20 min
• fatigue depends on mitochondrial content (density)
• ability of heart to circulate O2 (cardiac output, stroke volume, HR)

Question 18

Short Term Activities

Answer 18

• 10-180 seconds
• fatigue related to ability of body to buffer accumulating H+ from production of lactic acid

(still in anaerobic metab)

Question 19

Very Short Term Activities

Answer 19

• <10 seconds
• fatigue to depletion of PC stores

(immediate energy source)