Week 3 - Wearable devices and assessing autonomic control

Question 1

3 criterion measures of energy expenditure

Answer 1

1) Direct calorimetry
2) Indirect calorimetry
3) Doubly labelled water

Question 2

Direct calorimetry

Answer 2

measures heat exchange between the human body and the environment

(expensive, time consuming - 8hrs, and only measures when we are still)

Question 3

Indirect calorimetry

Answer 3

measures the type and rate of substrate utilization, whereby energy metabolism is estimated from respiratory gas exchange

(expensive, 5hrs of battery life so can’t measure EE over long period)

Question 4

Doubly labelled water

Answer 4

measures total CO2 production by observing the rates of appearance of isotopes over a 14-day period in urine after drinking a solution with isotopes in (Hydrogen (h2) and oxygen (018))

(expensive, time-consuming)

Question 5

Examples of wearable devices and what they can measure.

Answer 5

Examples: smart watches, skin patches, smart garments, headbands, mobile applications, biomechanical shoe insoles

Measure: HR, BR, stress, cognitive function, sleep, movement patterns, muscle electrical activity, strain/fatigue

Question 6

Describe the criterion measure of HR/ HR variability.

Answer 6

Electrocardiogram (ECG) which measures the electrical activity of the heart which is produced when the heart depolarizes and repolarizes during each heartbeat.

Question 7

What is the alternative method to ECG when measuring HR/HRV?

Answer 7

Photoplethysmography (PPG)
- Method that is able to detect change in heartbeat using a light emitted towards the skin which can detect variations in light absorption from the wrist or finger.

Question 8

Heart rate variability
- What is it?
- What does it measure the balance between?

Answer 8

• Beat-to-beat variation in the length of cardiac cycles (time difference between each R-wave)
• Measure of non-stationary balance between sympathetic and parasympathetic branches of the ANS (sympathovagal balance)

Question 9

The greater the HRV, the greater the…

Answer 9

modulatory influence of the cardiac vagus nerve on heart rate control

Question 10

What is low HRV a predictor of?

Answer 10

CV morbidity and mortality

Question 11

The activation of the …. NS and the suppression of the … NS can explain low HRV.

Answer 11

Sympathetic NS
Parasympathetic NS

Question 12

Factors that influence HRV

Answer 12

• HRV decrease with age
• Diurnal variation in HRV
• Daily physical activity highly correlated with improvement in HRV

Question 13

How is measuring HR and HRV applicable to sport science setting?

Answer 13

by measuring the impact of various stressors (such as lifestyle or training) on HR and HRV, we can make meaningful adjustments that can lead to better health and performance

e.g. if HRV is high, this indicates that PNS is activated and they are ready to exercise.

Question 14

Examples of acute stressors and chronic stressors

Answer 14

Acute: hard workout, travel, alcohol, caffeine
Chronic: illness, infection, work or study-related stress

Question 15

3 ways we can test the integrity of the ANS

Answer 15

1) Activity: normal function at resting state
2) Sensitivity: capacity of an organism or sense organ to respond to stimuli (head-up tilt)
3) Reactivity: the quality or state of being reactive or readily responsive to a stimulus, occurring as a result of stress (cold pressor test)