Chapter 14 Perceived Exertion

Setting

-characteristics of the scale administrator (gender, attractiveness) -exercise context (competition, research, medical evaluation) -exercise environment (outdoor, laboratory, hospital)

Heart Rate

-people may not be able to accurately sense changes in HR

•Cultural and social influences

-shape attitude toward physical activity -may influence general rating style

Relationship between exertion ratings and blood lactate during treadmill running experiment.

. It was concluded that LT is an important physiological anchor point for perception of effort that is not affected by state of training or gender. Trained and untrained men and women perceive the exercise intensity at LT as "somehwathard" (RPE = 13 to 14). During moderate-to-heavy exercise intensities, RPE is more closely linked to the metabolic and gas exchange alterations initiated at the LT than to % VO2max utilized.

Physiological states:

/ Blood doping ii/ Hypoxia iii/ Induced alkalosis iv/ Training v/ Fatigue

Limitations of VO2Method

1) Expensive 2) Difficult to monitor directly

RPE is a valid measure of exercise intensity because:

1) It is moderately-to-strongly correlated to objective measures of exercise intensity, and most importantly, 2) Experimental manipulations in exercise intensity, physical capacity or relevant psychological states result in appropriate changes in RPE.

limitations of RPE method

1) Liars 2) Some lack perceptual abilities i/ kids under 10 ii/ psychopathology 3) GXT estimation vs production mode specificity helps practice helps basically 1.Counting difficulties 2.Medication effects 3.Emotion effects 4.Position effects #3 need to keep the same mode, need about 3 days of practice to familiarize Production more useful than estimation If you test people on a bike then put them on a treadmill there is a little difference (mode specificity)

Limitations of the 6-20 scale

1. Ceiling effect 2. Not a ratio scale

People may not be able to accurately sense changes in HR

1. Heart rate 2. Oxygen uptake 3.Lactate *NOT directly sensed!

Experimental Evidence

1.) Force àhave measured at different intensities and found corresponding changes in RPE 2.) Power output àsame as force 3.) Psychology àhypnosis, worse with mental health issues, will skew RPE

There is experimental evidence that both feedback and central command play a role in perceived exertion.

1.Corollary discharge - a copy of the signal sent to the muscle (contraction) ● 2.Feedback (tendon vibration) ● 3.Corollary discharge and feedback combined ● 4.Alpha motor neuron - drugs blocking central command

What is the perceived exertion diagram

1.Exercise Stimulus 2.Physiological Response 3.Psychological Factors 4.Social Environmental Context All of these can influence of how difficult does it feel the exercise. How much effort are they giving with that intensity.

Of how much effort a person is giving during an exercise bout.

A Psychobiological Gestalt

What example is this?

A needle and sticking it to your finger, your sensation of that needle hitting your skin and finger is a passive process. You are detecting a sensation change. The sensation you will excite the sensory afferents in your finger and it will travel to your dorsal horn of the spinal cord and then go up a sensory afferent passageway to your brain. You are just sending signals to the brain .

Effects of sodium bicarbonate ingestion (NaHCO3) vs. Placebo - calcium carbonate (CaCO3) on the relationship between hydrogen ion concentration and local ratings of perceived exertion in the arms and legs

Blood pH was significantly higher under NaHCO3 than CaCO3 at pre-exercise and 80% Heart rate, and tidal volume did not differ between acid-base conditions at any exercise intensity. Respiratory rate did not differ between acid-base conditions at 20,40, or 60% but were significantly lower under NaHCO3 at 80%

•subject assigns a number to represent the intensity of a reference stimulus and then uses that number to rate subsequent stimuli

Estimation Task

When we talk about perceived exertion you got the exercise as the stimulus , it can be an exercise bike, treadmill, or lifting weights different types of stimulus. That intensity is going to influence the response of that persons effort to do that exercise. & this is their perceived exertion.

Example of Psychophysics. Exercise(stimulus)---> Perceived exertion (response).

That act to increase ventilation during exercise

Exercise stimulus

Signals from skeletal muscle that contribute directly to RPE?

Force = Ib & tension Stretch = Ia & II Pressure = Type III Noxious biochemicals = Type IV H+, bradykinin, 5HT Skin & muscle temperature = Type III and some IV

Who is Gunnar Borg?He is a Swedish psychologist. and ....

He has disseminated his finding about perceived exertion.Also developed the first scale.

Factors of physiological response?

Hormones Blood pressure Energy metabolism

Method:cycle ergometry to max during: normoxia(normal O2) hypoxia(reduced O2)

In hypoxia condition any given workload is rated at harder than O2condition There is a tight link between relative exercise intensity and RPE Weak relationship with absolute values and RPE

What is percieved exertion?

It is how difficult the exercise fields to a person while exercising (•Subjective detection and interpretation of the intensity of effort or strain during exercise). It is not the same exact thing as fatigue and pain.

•Large degree of variation in maximal HR •Difficulty in palpating and counting HR •Influenced by medication or emotional state •Position effects •HR reserve method has been shown to underestimate VO2peakat lower percentages and overestimate VO2peakat higher percentages of HR reserve

Limitations of HR Method

Effects of training following a heart-lung transplant on perceived exertion (n=36)

Manipulation of training Are inaccurate in their perception because afferent nerves are cut. There were significant reductions in submaximal values for minute ventilation (VE), ratings of perceived exertion, and diastolic blood pressure at equivalent workloads

Sensation definition

Passive process of detecting a stimulus following stimulation of a sensory organ

You do not sense or perceive pain until there's processing of that sensory processing information this is called

Perception

A person's perceived exertion so you can have a person that begins to start sweating so they perceive that they are working harder. HR goes up, blood pressure and cause a change .

Physiological Response

- subject adjusts the intensity of a stimulus to approximate a given proportion of the reference stimulus

Production task

Is the mood you are in good or bad you go to the gym. It's a big role on the person perceived exertion.

Psychological factors

What definition is this? are things related to your physical body that affect your thinking.

Psychological factors

__________ have been shown to influence perceived exertion, but most evidence is correlational and based on absolute workload

Psychosocial factors

Blood doping experiment The purpose of this review is to examine the evidence that links specific physiological processes with central signals of perceived exertion during dynamic exercise. The physiological processes thought to be associated with central signals

RPE did not differ between conditions when expressed as a function of percent of VO2max. The relative VO2 is more likely to be associated with a strong sensory signal. Central signals involving VE and the relative VO2 are proposed to act as an amplifier that potentiates local signals in proportion to the aerobic metabolic demand

context perception of effort is you can exercise with a group and that can influence your perception of effort. It can feel it is not difficult because of the atmosphere you are in.

Social environment context

Exercise intensity based on a duration up to 60 minutes

The interaction of these factors provide the overload stimulus. In general, the lower the stimulus the lower the training effect, and the greater the stimulus the greater the effect. As a result of specificity of training and the need for maintaining muscular strength and endurance, and flexibility of the major muscle groups, a well-rounded training program including aerobic and resistance training, and flexibility exercises is recommended

RPE can be used to: •serve as a subjective indicator of peak intensity •monitor the progression of the test and act as a cue to prepare the administrator for test termination •monitor changes in power output following exercise training •monitor individuals with health conditions •aid in communication among labs and clinics

Use of RPE in Graded Exercise Testing

•greater influence on perceived exertion at higher intensities • •RPE's of 13-15 often seen at ventilatory threshold

Ventilation

Perception definition

active process of interpreting sensory information

There is no "________"way to assess perception of effort. Each method has advantages and disadvantages

best

•transmits sensory (afferent) information regarding tension, velocity, and position from peripheral receptors in the muscle to the sensory cortex

feedback mechanism

•motor (efferent) commands are simultaneously transmitted to the working muscle andthe sensory cortex in the brain

feedforward mechanism-

- combined mechanism allows the complex processing and adjustment of afferent and efferent information

feedforward-feedback mechanism

The perception of exertion is a "____" or integration of physiological, psychological, and contextual cues

gestalt

Core body temperature

index of metabolic function; not a significant contributor to RPE independent of relative metabolic rate

What is psychophysics?

is the systematic study of sensory capacities by determining behavioral responses to physical changes in sensory stimuli.

Preferred exertion

may have important implications for promoting exercise adherence

skin temperature

may mediate RPE during thermal stress; changes in skin temperature can be sensed

Oxygen Uptake (VO2)

•% VO2peakis often highly correlated with RPE • •relationship can be altered by thermal stress, change in blood lactate, and training • •cannot be directly sensed

ACSM Guidelines for Exercise Prescription

•3-5 days/week •20-45 minutes/session •50-85% VO2max

Borg's Modified Power Law

•Borg modified Steven's Law for perceived exertion by adding 2 terms: a : perceptual noise b : stimulus threshold

Psychophysical Laws: Fechner's Law

•Fechner proposed that the relationship between a stimulus and a response was not linear

blood lactate

•RPE's of 13-15 are commonly seen at lactate threshold

Psychophysical Laws: Steven's Power Law

•Stevens proposed that the sensation of a stimulus grows as a power function of the stimulus

Borg CR10 Scale

•allows perceived exertion to follow a power function

Borg's 15-point RPE Scale

•yields a linear function