Pulmonary Physiology of Athletes

Pulmonary Physiology

of Athletes

Michael Ross, MD

Sports Medicine Physician

Rothman Institute

Director, The Performance Lab

VO2=CO x (A-V)O2

VO2=CO x (A-V)O2

• CO

• Cardiac Output

• Heart rate x Stroke Volume

VO2=CO x (A-V)O2

Arterial Oxygen

• =(Hgb x 1.39 x SaO2) + (PaO2 x 0.003)

Arterial Oxygen

• =(Hgb x 1.39 x SaO2) + (PaO2 x 0.003)

Arterial Oxygen

• =(Hgb x 1.39 x SaO2) + (PaO2 x 0.003)

Arterial Oxygen

• Hemoglobin

• Oxygen Saturation

Arterial Oxygen

• Oxygen Saturation

• Get the oxygen from outside the body to inside

the blood

• It’s gotta go through the lungs

VO2=CO x (A-V)O2

VO2=CO x (A-V)O2

Oxygen Extraction

• Mitochondria

• Oxygen diffusion:

capillary network

Exercise overview

• Endurance exercise is an interaction between the

heart, the lungs and the working muscle.

Training effect

• With endurance training, there are structural

changes that improve exercise performance

Heart Changes

• Increased LV size

• Increased LV wall thickness

Heart Changes

• Result in increased contractility, increased stroke

volume, increased cardiac output

Blood Changes

• Increase Red Blood Cell

mass

• Increase Plasma Volume

• Increase in total blood

volume results in

increased oxygen

carrying capacity

Muscle Changes

• Increase in Mitochondria

number and function

• Increase in type I fibers

• Increase in capillary

network

Lung Changes

None

Lung Changes

• There are no measurable

structural changes in the

lung

• The muscle’s ability to use oxygen is greater that

the ability to deliver oxygen to the working muscle

• Although there are no structural changes in the

lung from endurance training…

• The response to exercise by the respiratory

system has a large functional increase

Lung function changes

• Changes occur with exercise.

• Ventilation can increase 20 times with exercise

over baseline

• Increase in respiratory muscle endurance

Exercise Function

• As exercise intensity

increases the muscle

demand for oxygen

increases

• The heart and lungs work

together to supply that

demand

• At low intensity exercise, more oxygen is being

inhaled than carbon dioxide is being exhaled.

• Below the onset of lactic acid, increases in

ventilation precisely compensate for Acid

increase by controlling exhaled CO2

• As intensity increases, beyond the onset of lactic

acid (anaerobic metabolism) there is 4 times as

much CO2 to exhale.

• The increased demand for oxygen as well as the

increased needed to exhale the CO2 results in an

increase in ventilation.

• Increasing ventilation results in an increase in

both the size of each breath (tidal volume) and

the breathing frequency.

• Initially there is an increase in tidal volume until a

physiologic and anatomic limit is reached.

• Further increases in ventilation come from an

increase in breathing frequency.

Respiratory Muscles

• The increase in ventilation is carried out by

reparatory muscles

• Diaphragm as well as accessory muscles

Respiratory Muscles

• Create negative pressure to pull air into the lungs

• As intensity increases, pressure increases to

overcome airway resistance

• Upper airway dilates, glottis opens, bronchial

muscles relax

• As intensity increases, expiratory muscles are

recruited to help empty the lungs

• Increase in respiratory muscle strength is the only

pulmonary adaptation to exercise

Respiratory Limitations

• Exercise Induced

Hypoxemia

• Expiratory Flow Limitation

• Respiratory Muscle

Fatigue

• Exercise Induced Asthma

• Vocal Cord Dysfunction

Exercise-Induced Hypoxemia

• Oxygen Saturation can drop below 90% at max

intensity

• Occurs in up to 50% of athletes

• More common in women at a lower intensity

• Affects performance

Expiratory Flow Limitation

• Seen during heavy exercise

• Leads to hyperinflation/incomplete emptying

• Decreases lung compliance

• Pressure increases beyond the closing pressure

of the airways


• Pressure increases lead to

increased after load

• Decreased stroke volume

and cardiac output


• Women have smaller lung volumes and narrower

airways for a given volume

• More prone to EFL

• Masters athletes have a normal loss of recoil

leading to a reduction in maximal flow volume

loops


• Diagnosed with

exercise flow-volume

loops

• Seen in the small

airways


• Treat the airways responsible for air trapping

Respiratory Muscle Fatigue

• 4kg of muscle that can help

with respiration

• Diaphragm is fatigue

resistant

• The remaining accessory

muscles are fatiguable

Respiratory Muscles

• Can be trained by volume or resistanceSports Med. 2012 Aug 1;42(8):707-24.

• Both can be useful, sample size and

measurements make utility murky

• Bodybuilders have stronger respiratory muscle

strengthJ Sports Med Phys Fitness. 2013 Apr;53(2):139-45.

Respiratory Muscle Training

• Volume Loading

• Increases in maximum voluntary ventilation

• Resistive Training

• increased inspiratory pressure

Respiratory Muscle Training

• Inspiratory muscle strength

and endurance improved in

most studies.J Strength Cond Res. 2013 Jun;27(6):1643-63.

• Dependent on the type of

RMT employed.

Be a Rock Star

Exercise Induced Asthma

Traditionally diagnosed as a >10% drop in FEV1 after

exercise

Implies that pre-exercise levels are normal

(FEV1>80% predicted)

Symptoms include cough, shortness of breath

False Positives and

Negatives

74 Collegiate Athletes

16 positives

16 negatives using bronchodilator

4 positives using bronchodilator

The diagnosis of asthma and exercise-induced bronchospasm in division I athletes.Clin J Sport Med. 2009 Nov;19(6):482-6.

http://www.ncbi.nlm.nih.gov/pubmed/19898076

Prevalence

Forty-two of 107 athletes (39%)

were EIB positive.

Thirty-six of 42 EIB-positive

athletes (86%) had no prior

history of EIB or asthma.

Symptoms were not predictive of

EIB (P=0.44).

Prevalence

The prevalence of EIB was 36% in athletes with

negative symptoms and 35% for those with positive

symptoms.

Athletes in high-ventilation sports were significantly

more symptomatic (48%) than athletes in low-

ventilation sports (25%) (P=0.02)

Prevalence of exercise-induced bronchospasm in a cohort of varsity college athletes.Med Sci Sports Exerc. 2007 Sep;39(9):1487-92.



Exercise induced changes in lung mechanics

Underlying asthma that worsens with exercise


Symptoms occur after exercise

So, why do we care?

Respiratory Mechanics

As exercise intensity increases, tidal volumes

increase, followed by an increase in breathing

frequency

As frequency increases, expiratory time decreases

and inspiratory time increases


As exercise intensity increases, increasingly more

anaerobic (Type II, Fast twitch, white meat) fibers are

recruited

Under anaerobic conditions CO2 is formed 4 times

more than aerobic exercise

Increased ventilatory demand to compensate for rise

in CO2


Less time in expiration

More CO2 to expire


Bronchoconstriction makes exhalation more difficult

If the lungs aren’t empted of CO2, they can’t be filled

with O2

VO2 = CO x (A-V)O2

VO2 = Cardiac Output x (Arterial O2 -Venous O2)

VO2 = HR x SV x (Arterial O2 -Venous O2)

VO2 = CO x (A-V)O2

VO2 = Cardiac Output x (Arterial O2 -Venous O2)

VO2 = HR x SV x (Arterial O2 -Venous O2)


Clearly affects exercise, even if symptoms are after

exercise

Why is it hard to treat?

Why do symptoms persist despite normal tests?

Small and Large Airways

FEV1

FEF 25/75

FEV1

Large airway measure.

Asthma is diagnosed when FEV1 is less than 80% of

predicted

Exercise asthma is diagnosed when there is a 7-10%

drop in FEV1 before and after exercise

Flow Volume Loop

Fl

o

w

Flow Volume Loop

Fl

o

w

FEF 25-75

Small airway measurements.

Vital Capacity is divided into quarters.

The first 25% of Vital Capacity is FEF25



Flow Volume Loop

Fl

o

w

Small Airways

The pathophysiology in asthma involves not only the

proximal large airways, but also the distal small

airways

The small airways are an important therapeutic target

Extensive disease can be present in the small airways

with little abnormality in conventional pulmonary

function tests.

Usmani OS, Barnes PJ. Ann Med. 2011 Jun 17. Assessing and treating small airways disease in asthma and chronic obstructive pullmonary disease


Exercise Flow Volume Loop

FEF25-75

Small airways

Small airways do not necessarily cause shortness of

breath with exercise

May cause cough

Small airways may be responsible for muscle fatigue

Small Airway Restriction

Small Airway Prevalence PosterSmall Airway Prevalence Poster

Results

Methods

Our current working definition of asthma ignores

the fact that athletes frequently have a FEV1 that

is higher than expected. Athletes may have

airway restriction that is not measured by FEV1

alone. Perhaps the lack of diagnostic utility of the

FEV1 explains the lack of utility of symptoms and

history. If an athlete has dyspnea with exertion, it

is important to look at comprehensive measures of

lung function, not just the FEV1. This study looks

at multiple lung parameters to examine the

prevalence of abnormalities.

In this retrospective review, 304 athletes with

exercise related respiratory symptoms or fatigue

were tested to exhaustion using a ramp protocol.

Pulmonary function testing was performed before

and 10 minutes after exercise by recording both

large airway measurements (FEV1) and the small

airways measurements (FEF 25/75.)

Clinical Relevance

Conclusion

Background

Figure 1

Figure 1 : Normal FEV1 and small airway

restriction

304 athletes were included. 281 (92.4%) had

normal or above normal pre-exercise FEV1

(average FEV1 = 104.92% of predicted)(SD

14.26). FEF 25/75 averaged 70.73% of predicted

in the normal FEV1 group (SD 24.7).

Of the normal FEV1 group, 183 (65.12%) had

small airway limitations (F25/75 <80.)

23 athletes (7.6%) had reduced FEV1 pre-

exercise (average=62.7% of predicted)(SD 13.11).

23 of 23 (100%) of these athletes had below

normal FEF 25/75 values (<80%predicted)

(average = 38.9% of predicted)(SD 15.7).

Following exercise, the normal FEV1 group had

43 subjects (15.3%) with significant decreases in

FEV1 of > 10% (Average decrease was 17.6%

)(SD 7.07) that would qualify as exercise-induced

bronchospasm. 10 of these 43 (23.2%) subjects

also had a decrease in the FEF 25/75 of > 26%

(average change was 15.7)(SD was 19.38).

In the abnormal FEV1 group, 5 of the 23 subjects

(21.7%) had a drop in their FEV1 following

exercise, with 0 of 25 (0%) subjects showing

worsening FEF 25/75 (decrease > 26%).

Athletes presenting with fatigue and/or respiratory

symptoms during exertion had less than predicted

small airway measurements.

By only including FEV1 in the diagnosis of asthma

and exercise induced asthma, small airway

pathology in nearly half of the “normal” patients is

overlooked. Because the treatment is different for

exercise induced asthma and baseline asthma

that worsens with exercise, better criteria for

asthma in athletes must be developed so that

athletes who need treatment aren’t overlooked.

Small Airway Disease Prevalence in Athletes Michael Ross, MD, Brandon Eck, DO

Rothman Institute of Orthopedics, Thomas Jefferson University Hospital, Philadelphia, Pennsylvania

Purpose

To examine the prevalence of small airway

disease in athletes

Figure 2

Figure 2: Flow/Volume loop with higher than

normal FEV1 and scooping of the descending

limb

Results

Methods

Asthma in athletes can be difficult to diagnose.

Because of the higher than normal lung volumes,

an athlete may be in bronchospasm yet still have

normal lung volumes when compared to the

reference values for the general population. It is

hypothesized that if there is a limitation of airflow,

the Vital Capacity during exhalation (VCex) will be

less than the maximal Vital Capacity (VCmax) and

the resultant VCex/VCmax ratio (VC ratio) will be

less than 1. This study examines the relationship

between the VC ratio and asthma.

Retrospective review of 359 Cardio-Pulmonary

Exercise Tests in athletes were reviewed. The

VCex/VCmax ratio was calculated for every

patient. A VCex/VCmax ratio less than one was

labeled as limited expiratory flow. A VCex/VCmax

ratio of one was considered normal. The

associations between lower VCmax ratios and

lung function was evaluated.

Clinical Relevance

Conclusion

Background

Figure 1

Figure 1 : Spirogram demonstrating a

decreased VCex/VCmax ratio

A Spearman rho was used to analyze the

relationship between the VCex/VCmax ratio and

FEV1, FEV1 change with exercise, FEF50, FEF50

change with exercise and FEV1%. Pre-exercise

FEV1, Post-exercise FEV 1, and percent change

of FEV1 were all significantly but not strongly

associated (rho = 0.16 to 0.24).

Using the VCex/VCmax ratio is helpful for

screening for asthma and exercise-induced

asthma in athletes using spirometry.

The VCex/VCmax ratio correlates with the FEV1

as well as an exercise-associated change in

FEV1, making this a good screening tool for

baseline asthma in athletes as well as exercise

induced asthma. The VCex/VCmax ratio has a

role in the diagnosis of asthma in athletes in

whom the FEV1 values might otherwise be normal

for the general population, but might be lower than

expected for athletes. Treating asthma for a

normalization of the VCex/VCmax ratio might be

viable in patients with exertional dyspnea.

VCex/VCmax Ratio as an indicator of asthma in athletesMichael Ross, MD, Brandon Eck, DO


Purpose

To examine the role of using VCex/VCmax as a

diagnostic tool for asthma in athletes

VCex/VCmax

Results

Methods

Asthma in athletes can be difficult to diagnose.

Symptoms are less likely to be an aid in diagnosis

and baseline lung volumes may be elevated

because of endurance training.

Endurance athletes have an average FEV1 of

112% of predicted. If endurance athletes are

compared to the normal population, an athlete

may have normal values but still be broncho-

contstricted. The FEV1/FVC ratio has been used

in the diagnosis and stratification of chronic lung

disease but it has not yet been used for athletes.

The study examines the utility of an internal

comparison (FEV1/FVC ratio) to diagnose asthma

in athletes.

A retrospective chart review was performed on

304 patients who underwent Cardio Pulmonary

Exercise Testing. Pre and post exercise

FEV1/FVC ratios were calculated and compared

to Gold Criteria for pulmonary obstruction.

Clinical Relevance

Conclusion

Background

Figure 1

Figure 1 : Post exercise FEV1/FVC values in

the GOLD Criteria

A linear regression analysis was completed to

evaluate the relationship between the FEV1/FVC

ratio and Gold Criteria. There is a significant

correlation between post exercise FEV1/FVC ratio

and worsening obstruction measured by the

GOLD criteria. P=0.0002

The post-exercise FEV1/FVC ratio is a useful for

diagnosing asthma in athletes who have

undergone an exercise challenge test.

By comparing the athlete to his own lung function,

the difficulty in trying to compare an athlete to the

normal population can be avoided.

The post-exercise FEV1/FVC ratio allows

diagnosis of exercise related asthma conditions

even if the athletes have normal FEV1 compared

to the predicted values, resulting in fewer missed

diagnoses. Establishing a diagnosis of baseline

obstruction is important in differentiating between

baseline asthma and exercise-induced

bronchoconstriction, as the treatment options

differ between the two conditions.

FEV1/FVC Ratio as an indicator of asthma in athletesMichael Ross, MD, Brandon Eck, DO


Purpose

To examine the role of FEV1/FVC as a diagnostic

tool for asthma in athletes.

Table 1

Table 1 : GOLD Criteria

0

0.2

0.4

0.6

0.8

Controls

Gold 1

Gold 3

0.74 0.8

0.59

0.53

0.45FE

V1/F

VC

Gold 1 FEV1/FVC < 0.7 FEV1 <80% perdicted

Gold 2 FEV1/FVC < 0.7 50%<FEV1 < 80% predicted

Gold 3 FEV1/FVC < 0.7 30%<FEV1<50% predicted

Gold 4 FEV1/FVC < 0.7 FEV1 <30% predicted

Lactic Acidosis

Hydrogen Ions are buffered by Bicarbonate

H+ + HCO3- <=> H2CO3 <=> H2O + CO2

Water and Carbon Dioxide are exhaled

Muscle Fatigue

Accumulation of H+ leads to muscle fatigue

Decrease in both force and velocity of contractions

Small Airway Restriction

Treatment

Inhaled corticosteroids and Beta agonists: HFA

aerosols provide better penetration for small airways

Formoterol/budesonide, ciclesonide,

beclomethasone, flunisolide

Inhaled beta agonists v. Leukotriene agonists for peak

flow declines

Treatment

Pulmonary Rehabilitation: Endurance training to help

increase metabolic compensation for lactic acidosis

Physical training showed improvement in maximum

oxygen uptake without affecting pulmonary function

People with stable asthma should be able to

exercise without symptom exacerbation. Cochrane Database Syst Rev. 2013

Sep 30;9:CD001116. Physical training for asthma.Carson.

Thank You

• Questions?

Vocal Cord Dysfunction

Normal Breathing:

Vocal cords open with

respiration and close with

swallowing


Abnormal Breathing:

Vocal cords paradoxically close

with inhalation or early

expiration

VCD Symptoms

Inspiratory difficulty

Choking sensation

Stridor

Concommitant psychiatric diagnosis

VCD: Triggers

Idiopathic

Acid Reflux

Post-nasal drip

VCD Exam

Inspiratory wheeze at larynx does not transmit to

thorax

Diagnosis

Laryngoscopy (60% sensitive if asymptomatic--100%

sensitive during an attack)

Truncated inspiratory limb on flow/volume loop


Fl

o

w

VCD: Treatment

Speech Pathology =>Breathing Manuvers

rapid, shallow panting

diaphragmatic breathing

nasal breathing

straw/purse-lipped/hissing breathing

VCD Treatment

H2 Blockers/Proton Pump Inhibitors

Nasal Steroids/Antihistamines

Psychological counseling

VCD: Treatment

Botulinum Toxin

Administered under

EMG guidance into

vocal folds


Consider in patients with refractory asthma

More than half have concomitant asthma


Large Airways (FEV1 decline) are responsible for

shortness of breath

Small Airways (FEF25/75) are responsible for lactic

acidosis and expiratory flow limitations

Exercise Flow/Volume loops allow for correlation

between performance and airway disease

Documents

Pulmonary Physiology of Athletes