KINS 4400: Exam 4 _ CDupdated

What are the benefits of feeling energetic? (3)

1. Better learning

2. Greater enjoyment of life

3. Better work productivity

Percentages of people reporting feelings of fatigue in the last week? month? 6 months?

about 30%, 25% and 20%

What is the total yearly cost of fatigue globally?

$500 billion

what are the roles of anxiety, depression, and fatigue in exercise?

Anxiety, depression and fatigue impair exercise that could help relieve them

__ RCTs of chronic exercise show increased feelings of energy compared to control conditions

70 RCTs, effect size = .37

Cardiac rehabilitation exercise programs improve symptoms of fatigue more than anxiety or depression. What are the effect sizes of this?

Fatigue: d = .59

Anxiety: d = .40

Depression: d = .35

_ days of physical inactivity leads to low energy

3

effect size of energy post-exericse compared to a control group

d = .47

_______ exercise energizes better than _________

aerobic; resistance

Exercise ______ is a moderator in the effect of exercise on mood

Intensity

low > vigourous > moderate

The energy boost from exercise is largest:

After low-intensity aerobic exercise performed by those with low to moderate baseline feelings of energy

6 neurotransmitters that alter feelings of energy during exercise

1. Dopamine

2. NE

3. Serotonin

4. Acetylcholine

5. Adenosine

6. Histamine

What 4 factors play into perception of effort?

1. Physiological factors: if I carbload, my physiology is influenced, and running feels easier

2. Psychological factors: exercise feels harder when you're depressed

3. Environment: working out when it's hot outside vs. an air conditioned room, also working out with someone else may feel easier

4. Exercise stimulus: 10 stairs feels easier than 100 stairs

Ways to boost short-term energy

1. Naps

2. Taking certain foods, beverages, drugs (glucose and stimulants)

3. Engage in brain-activating behaviors

4. Engage in physical activity

Light exposure _____

energy (study done, effect size d=.15)

What are the two ways to define percieved exertion?

1. Feedforward: focusing on the effort YOU put into a physical activity

2. Feedback: Focusing on sensations your brain is getting (sweating, heavy breathing, etc.)

What are the 4 scale types

Nominal, ordinal, interval, ratio

Nominal scale

Giving a number to something in order to categorize it (like a license plate)

Ordinal scale

Ranking something (1st, 2nd, 3rd) no indication on performance given

Interval scale

Provides equivalent distances (like temperature)

Ratio

The best scale, has a true zero and goes to infinity

Why is RPE ordinal?

(idk)

What are the two types of ratio scales?

1. Magnitude estimation

2. Magnitude production

Ratio scales: magnitude estimation

The observer makes a direct numerical estimate of the perceived magnitude of a stimulus. In our case, no scale was given, but participants were asked to come up with one on there own.

Example in class: Dr. O said "bulldogs" at 3 different volumes, and we were asked to assign them a numerical value

No matter what scale was chosen, the softest one was given the lowest number, the loudest one the highest number, and the medium one a moderate number

What this shows: we are able to ESTIMATE the MAGNITUDE of the loudness of his voice even if everyone doesn't follow the same scale

Ratio scales: Magnitude production

Example: If a participant is on a treadmill, we can instruct them to run at 2x the intensity, .5x the intensity, etc. They are able to produce a certain magnitude that is specific to them.

As power output increases linearly,

perception of how intense the exercise stimulus feels grows exponentially

What is steven's power law?

The relationship between exercise stimuli and perception of effort

Magnitude of perception = (constant)*(stimulus intensity)^nth power

What is the main disadvantage of ratio scales?

Inter-individual comparisons are not possible

- Everyone is on a different grading scale

Who is Gunnar Borg?

He made ways for our field to measure perception of effort more easily "Borg scales" can be found everywhere. He is the most highly cited exercise psychologist

Percieved exterion scales

1. Borg's 6-20 scale:

- Most commonly used

- Useful for most applications

- Ordinal scale

2. Borg's 0-10 scale

- Ordinal, but ratio-like responses

- For studying non-linear exercise responses

Why does the borg 6-20 scale start at 6?

It generally corresponds with heart rate

(if my RPE is 13, which is somewhat hard, my heart rate is probably around 130bpm)

The 6-20 scale was designed to be related to heart rate response to what? Why? And was originally done on what group?

Cycling; It was an easy way to measure heart rate without having to get expensive equiment that they didn't have access to; Swedish men

Why might the Borg 6-20 scale not reflect an accurate heart rate with swimmers?

Since your sideways, your body doesn't have to bring blood to your head. Also, your face is in cold water.

What are the three limitations to the 6-20 scale?

1. Ceiling effect: Since it has a top number, people will avoid giving the top number because they don't want to hit the ceiling. Not truthful answers

2. Not a ratio scale

3. Assumes all maxes are percieved the same

How does the 0-10 scale have ratio like properties?

- The placement of the words allow for a curved linear relationship

- 10 is an "almost max" with an asteriks that indicates that you can go to higher numbers

Why is it important that the 0-10 scale gives curved linear relationship?

- Physiological responses are curved linear (like HR and lactate)

What are the four instructions for giving the Borg scales to a client?

1. Define percieved exertion

2. Explain differential ratings

3. No right or wrong answers

4. Anchor the perceptual stimuli

Differential ratings (3)

1. Overall

2. Local: "What body part?" --> Can help identify specific problems

3. Central: Mostly breathing

This can clue you in to specific pathology issues in a clinical exercise setting

Anchor the perceptual range

1. Present stimuli: Start low so they know where a 6 is, go to their max so they know where a 20 is. Come back next week since you've calibrated the scale

2. By definition: Usually compare it to other things

Studies show a large linear correlation between __ and RPE and curved linear between ______ and RPE

HR (r=.74); lactate (r=.83)

We are recommended to do 150 minutes of moderate intensity exercise a week, which is a what on the RPE scale?

13 at MINIMUM, vigorous is around 15

Absolute exercise stimuli vs absolute physiolgical responses

Absolute exercise stimuli:

- Power output, treadmill speed/grade, weight lifted/lowered

Absolute physiological responses:

- HR, oxygen uptake, lactate

Physiological responses to exercise stimuli can be variable based on whats going on in the body

Exercise stimuli are moderate-to-highly correlated to RPE

Experiments that show that RPE ratings are valid: Absolute exercise stimulus and physiological states

Absolute exercise stimulus: Power output, treadmill speed

Physiological states: Blood doping, Fatigue responses induced by acute exercise duration, training adaptations, hypoxia

Power output

When given random power wattages, the RPE of the wattages correspond well.

What is "just noticable difference"

People can detect changes in wattage around 20 watts

(wouldn't notice change from 100 to 110, but would notice 100 to 120)

Treadmill speed: What are "Clamp" Studies?

If you keep the speed constant, your RPE will go up as time goes on

If you keep the RPE constant, your speed will go down as time goes on

What is blood doping?

When you take blood out of your body, freeze it, let your body make more, and then putting your blood back into your body

The logic: the more RBC you have, the more oxygen being delivered to your muscles, the more endurance you'll have.

SO at any submaximal intensity (not max), it'll feel easier

Training induced adaptations

As you train and gain adaptations (mitochondria, increase in heart size, etc) what once felt hard will feel easier

Hypoxia: The study with reduced oxygen showed that

At any given submaximal intensity, it feels easier at normoxic conditions and harder at hypoxic conditions

What are the three systems that contribute to exertion?

1. Respiratory: Respiratory muscles and lung afferents

2. Metabolic: %vo2max - indirect - no receptor/afferents

3. Peripheral: Afferent sensing muscle force and byproducts (ex) H+, bradykinin, etc.)

Respiratory system and contribution to exertion based on % of VO2max

< 50%: Limited

50-70%: Moderate

> 70%: Significant

Metabolic system and contribution to exertion based on % of VO2max

< 50% Proportional

50-70%: Proportional

> 70%: Proportional

Peripheral system and contribution to exertion based on % of VO2max

Dominant at all % of VO2max

Why is our peripheral dominant?

At all intensities, our periphery is sending signals to our brain, telling our brain that we are working

ex) if we are lifting a waterbottle, we know we're working because of our PERIPHERY,

Why is RPE a valid measure of exercise intensity? (2 reasons)

1. Moderately to strongly correlated to objective measures of exercise intensity,

2. Experimental manipulations in exercise intensity, physical capacity, or relevant psychological states result in appropriate changes in RPE

What are the two CNS mechanisms for perceived exertion?

1. A copy of the central command signal (corollary discharge)

2. Afferent feedback

What is the corticospinal tract?

A nerve that goes from the motor cortex to the spine

What is the central command signal?

A signal that is sent from the brain (specifically the motor cortex) at an intensity that corresponds to the intensity of the activity being performed

ex) if I'm lifting a weight at a light intensity, then a weak signal is sent to the brain.

What is the corollary discharge signal?

A signal sent at the same time as the central command signal, but it is from the sensory cortex. It is at the same intensity (this is why it's accurate) as the motor cortex, and checks percieved exertion.

What is afferent feedback?

The golgi tendon organ, that detects force, sends an afferent signal to the brain with an intensity that corresponds to the weight being lifted

What experiment has been done to show that percieved exertion is associated with corrollary discharge?

Acetylcholine is blocked partially using Curare (dripped in your veins during a curl test) This would cause a stronger signal from the motor cortex to lift the same weight. The central command signal would increase, which would also increase the corollary discharge signal. However, since the weight itself wouldn't change, the feedback part (from the golgi tendon organ) shouldn't change. If RPE is correlated with corollary discharge, then we would expect RPE to go up, and it does.

What experimental evidence has shown that RPE is correlated with both corollary discharge and afferent feedback

you perform a max strength test with your right and left legs. and you find that the RPE at different percentages of your max on that leg is the same for both leg

ex) if my left leg can lift 100lbs, and the right only 90lbs, at 33% of that, (33lbs for left leg, 30lbs for right leg) the RPE would be the same

In the experiment, they vibrated one of the legs (which I guess means the golgi tendon organ will detect more force?), and that leg reported a higher RPE at the same max percentage.

What this shows: More afferent activation makes things harder

Why does most exercise equipment make it harder for looking at whats active in the brain?

The metal makes MRI's impossible

Limitations of VO2max tests in exercise prescription

1. Expensive ($30,000)

2. Difficult to monitor directly

Limitations of HR method in exercise prescription

1. Counting difficulties (inaccurate, pressing on carotid artery slows down HR)

2. Medication effects (10% on beta blockers, slows down HR)

3. Emotion effects (nervous = higher HR)

4. Position effects

Limitations of RPE method in exercise prescription

1. Liars (to look better)

2. some lack perceptual ability (kids, psycho/neuro pathology)

3. Graded exercise test estimation vs. production

Are there any child friendly scales to measure percieved exertion?

Yes, with pictures!

What is fatigue?

An exercise induced, transient (doesn't last long) reduction in the ability to produce muscle force given adequate motivation to perform

What evidence suggests that fatigue during short duration exercise (

1. Pace does not steadily decline in world races (if fatigue was just because of a build up of chemicals, we would expect pace to decline, but this is NOT what we find)

2. Experimental manipulation of the:

- Muscle (twitch interpolation)

- Brain: (transcranial magnetic stim, stimulant drugs/placebos, acoustic stimuli, cognitive work)

Study we discussed in class with electrical stimulation regarding the CNS component of fatigue

Overtime, as you do max tests, the force produced will be less and less (like if I do a max deadlift, take a break, and then do it again, my max will be less than the first time)

In the study, e-stim was given during the recovery period in between maxes. The amount of force produced during the e-stim went down as well. This shows that fatigue also has a muscle component, since the stimulation would have only activated the muscles

Also, in the study, stimulation was given DURING the max. The more contractions you have done, the more force produced in the muscle bc of the stimulation. This shows that there is a CNS component, since you are able to produce more force with the e-stim.

The amount of added force due to e-stim is larger in patients with neurological disorders. This means...

Those with MS would be fatigued more quickly compared to someone without a brain problem. They will have more CNS fatigue

How are stimulant drugs evidence of correlation between CNS and fatigue?

If they improve performance, since they act on the CNS, this is HUGE evidence

What are examples of stimulant drugs?

1. Ephedra

2. Ritalin

3. Antidepressants:

4. Caffeine

Ephedra

Examples include ephedrine, pseudoephedrine

Increases norepinephrine

Ritalin

Increases dopamine

Antidepressants

Buproprion (effexor, wellbutrin): increases norepinephrine and dopamine

Sertraline (prosax, zoloft): increases serotonin

Caffeine

increases nore, dopamine, serotonin

Study involving pseudophedrine and runners

In a double blind study, some runners were given 2.5mg/kg BW of pseudoephedrine and asked to complete a 1500 meter run.

The runners who had the placebo ran on average a 4:40 mile

The ones with the drug ran a 4:34 mile

This is a 5.8 second difference, with an effect size of 1.33

This shows: Stimulant drugs improve performance!

What study was done, showing that auditory input can stimulate the brain and effect performance?

A group did elbow flexion maxes every minute, then took a break. Then, randomly, a pistol would go off. The fatigue resulted in a weight that trended downward. However, whenever the pistol would go off, there would be a spike in performance.

Who is Angelo Mosso? How did he study fatigue?

The first person to study fatigue.

How he studied: Used an ergograph

What did Angelo Mosso's study show?

Increased mental work contributes to fatigue

He lifted a weight with his finger and put it down repeatedly. Overtime, there was fatigue. The day before a lecture, he was able to last longer than the day he had a lecture, because more mental work was done.

Mental fatigue before competition appears to reduce short-duration endurance performance. What study was done to show this?

One group was asked to perform a cognitive task and the other was asked to watch a video before a competition. The group asked to watch the video had a longer time to exhaustion than the other group.

Study done by MARCORA, a modern day Mosso

Whatever circuit you use to think is the same one used activating muscle

What evidence suggests that fatigue during long duration exercise ( >15 minutes) has a CNS component? (4)

1. Rat studies: Intercranial self-stimulation

2. Stimulant drug manipulations

3. Glucose manipulations

4. Core/brain temperature manipulations

Rat studies: Intercranial self-stimulation: explanation

The rats got ventral tegmental stimulation as long as they interrupted the photo-cell beam (basically, they got the shock if they kept running) This shock is PLEASURABLE to the rat

Other rats got an aversive when they weren't running

The question: do we use positive or negative reinforcement to optimize results?

Rat studies: Intercranial self-stimulation: results

The time to exhaustion was much better (64 minutes) with the stimulation of the ventral tegmentum area (linked to pleasure) than with teh adverse stimuli (43 minutes)

effect size: d = 2.1

More motivated and/or less centrally fatigued

Dopamine + nucleus incumbens play a big part in getting people to work

Stimulant drug manipulations: cycling

One placebo group, one group given 300mg of bupropion (a dopamine and NE reuptake inhibitor) at bed and at wake. This means that dopamine and NE would be in the system LONGER (more of an effect)

60 minute cycling, time trial following, power output tracked

Stimulant drug manipulations: cycling: results

There was no effect on the drug in cool conditions, but big effect in heat

Stimulant drug manipulations: Serotonin: Who did this? what did they do?

Romain Meeusen and colleagues summarized 25 human studies and 25 animal studies, concluded there is NO evidence to support the hypothesis that elevated levels of serotonin cause central fatigue

Stimulant drug manipulations: Serotonin: Dialysis experiment

Romain did a microdialysis on rats during acute exercise to see what neurotransmitters are released during exercise.

What he found: No increase in serotonin during exercise

Glucose manipulations

In this study, one group rinsed their mouth out with 6.4% glucose and 6.4% maltodextrin. Another placebo group

In strength + sprint exercises, no effect

Performance in 30-60 minute events showed improvement of 2-3%, when carbs are just in mouth. Similar effect to ingested carbs as well.

Glucose manipulations: Why does just "swooshing" glucose in mouth work?

Sensory afferent carrying info about sweetness to the brain

What brain areas are targeted in the glucose manipulation?

dorsolateral prefrontal cortex, anterior cingulate cortex, and the accumbens

Core/brain temperature: The reasoning

One of the main limits to endurance performance is core body/brain temeperature. As you do endurance performance, you heat up. To counteract this, you sweat. The high temperature in the brain, your body interprets as dangerous, which inhibits the motor cortex from functioning the right way. If you "pre-cool" (lower body temp before endurance event) you have longer to go before you hit these high temps. (Focus on the summaries, not the experiment) This is due to the BRAIN not wanting to reach the critical core temp, not the muscle

Core/brain temperature: Effect

Small effect in performance: d =.43

Large effect for prolonged exercise in the heat (d=1.91)

In the study, the people when 1.1% faster when pre-cooled

What is circadian rhythm?

Self-sustained fluctuations in an aspect, biology, psychology, or behavior with a period of about 24 hours

The impact of the circadian rhythm stems from this, and is considered the "master circadian clock"

Suprachiasmatic nucleus

Primary projections: Forebrain, thalamus, hypothalamus

Secondy projection:

- Hippocampus (memory)

- Pre-frontal cortex (attention)

- amygdala (emotion)

- Anterior pituitary (endocrine)

- reticular formation (sleep/wake)

- pineal (melatonin)

- pre-optic area (temp)

Characteristics of a rhythm

1. Amplitude: Distance from peak to average (young, healthy tissue has a larger amplitude)

2. Phase: Any point on the rhythm

3. Period: Peak of rhtyhm to peak of rhythm (24 hours)

What are the most commonly used circadian rhythm markers in human studies

1. Core body temperature

2. melatonin onset

What is a circadian phase shift

Using light, melatonin and/or exercise to shift rhythms

can be "game changing" for performance and health

Why do athletes use phase shifts?

If athletes travel across time zones, there body may be at "peak" performance at 4am, when they need to be ready at 4pm. So, before they leave, they may learn how to shift their rhythms in order to optimize performance