Sport Science: Acute Responses and Chronic Adaptations to Exercise

Flashcards covering acute responses to exercise and chronic training adaptations across the cardiovascular, respiratory, and muscular systems, including physiological definitions, calculations, and visual graph interpretations.

What is the formula used to calculate an individual's Maximum Heart Rate ($\text{MHR}$)?

$$\text{Maximum Heart Rate} = 220 - \text{Age}$$

What percentage ranges of Maximum Heart Rate define the aerobic zone and the anaerobic zone?

Aerobic Zone: $70\text{--}84\%$ of Maximum Heart Rate\nAnaerobic Zone: $85\text{--}100\%$ of Maximum Heart Rate

For a $16$-year-old individual, what is the Maximum Heart Rate and the corresponding aerobic training zone in beats per minute?

$\text{MHR} = 220 - 16 = 204\,\text{bpm}$\nAerobic Zone ($70\text{--}84\%$) = $143\text{--}171\,\text{bpm}$ ($204 \times 0.70 = 142.8 \approx 143\,\text{bpm}$; $204 \times 0.84 = 171.36 \approx 171\,\text{bpm}$)

How does an acute response to exercise differ from a chronic adaptation to training?

An acute response is an immediate physiological change at the onset of exercise to cope with exercise demands that returns to pre-exercise levels after the bout. A chronic adaptation is a long-term physiological change to body systems resulting from training over $6+$ weeks.

What two main factors determine the significance of the body's acute responses to exercise?

1. Duration = time ($\text{mins}$)\n2. Intensity = $\text{\% of Max HR}$

Which three body systems experience acute responses during exercise?

1. Respiratory system\n2. Cardiovascular system\n3. Muscular system

What are the three distinct phases of oxygen consumption during an exercise session and recovery?

1. Oxygen deficit (at the start)\n2. Steady State (during exercise)\n3. Excess Post Exercise Oxygen Consumption, or EPOC (after exercise stops)

What is oxygen deficit, and why does it occur at the start of exercise?

Oxygen deficit is the difference between the oxygen required by the body and what it actually manages to take in at the start of exercise. It occurs because the body needs time to adjust to sudden energy demands, causing energy to initially be supplied anaerobically.

How is steady state defined during exercise, and what physiological indicator typically reflects it?

Steady state is the state where oxygen supply equals oxygen demand ($\text{Oxygen Supply} = \text{Oxygen Demand}$). It is generally indicated by a consistent, plateaued heart rate within the aerobic zone.

What is Excess Post Exercise Oxygen Consumption (EPOC), and what are its two primary physiological functions?

EPOC is the elevated oxygen consumption that occurs after exercise concludes to return the body to resting levels. Its functions are to aid in the removal of accumulated $\text{H}^+$ (hydrogen ions) from the muscles and to restore creatine phosphate stores to resting levels.

What is ventilation ($V$), and what formula is used to calculate it?

Ventilation is the total volume of air breathed (inhalation and exhalation) per minute ($\text{L/min}$). It is calculated as:\n$V = \text{RR} \times \text{TV}$\n(where $\text{RR}$ is Respiratory Rate and $\text{TV}$ is Tidal Volume).

What causes the slight increase in ventilation and heart rate observed just prior to the start of exercise?

An anticipatory response as the body prepares for exercise.

What is stroke volume ($\text{SV}$), and which heart chamber ejects it?

Stroke volume is the volume of blood ejected with each beat from the left ventricle into the aorta artery to supply oxygenated blood to the body, measured in $\text{mL/beat}$.

What is cardiac output ($Q$), and what formula expresses its relationship with heart rate and stroke volume?

Cardiac output is the total volume of blood pumped by the heart per minute ($\text{L/min}$). It is calculated as:\n$Q = \text{HR} \times \text{SV}$\n(Heart Rate $\times$ Stroke Volume).

What is cardiac hypertrophy, and how does it affect stroke volume?

Cardiac hypertrophy is the thickening or enlargement of the muscular wall of the ventricle (specifically the left ventricle) as a result of exercise. It allows the heart to contract with greater force and pump out more blood per contraction, increasing stroke volume.

In the context of thermoregulation and exercise blood flow, which vascular mechanism is shown on the right side of this diagram, and what is its role?

Vasodilation. Blood vessels widen toward the skin surface, increasing blood flow to promote sweating and allow body heat to dissipate across the epidermis into the atmosphere.

How does blood flow redistribution occur during heavy exercise compared to rest?

Vasoconstriction narrows blood vessels to reduce flow to non-essential organs (such as the liver, kidneys, stomach, and intestines), while vasodilation widens vessels to direct up to $80\text{--}87\%$ of cardiac output to working skeletal muscles and the skin.

Which brain structure is responsible for monitoring and regulating the cardiovascular adjustments required for blood flow redistribution?

The medulla, located in the brainstem.

What target internal body temperature range does thermoregulation strive to maintain during exercise?

Between $36\text{--}37.5\,^{\circ}\text{C}$.

Which food fuels are depleted to produce ATP during exercise, and which metabolic by-products accumulate during anaerobic intensity ($85\%+$ of $\text{MHR}$)?

Food fuels depleted: Carbohydrates, Fats, and Proteins (to a lesser extent).\nMetabolic by-products accumulated: Lactate and Hydrogen ions ($\text{H}^+$).

What is the difference between $\text{VO}_2$ and $\text{VO}_2\text{ Max}$?

$\text{VO}_2$ is the volume of oxygen taken up and used by the body per minute. $\text{VO}_2\text{ Max}$ is the maximum volume of oxygen the body can take in (respiratory system), transport (cardiovascular system), and use (muscular system).

In what unit is relative $\text{VO}_2\text{ Max}$ expressed, and what does this unit represent?

It is expressed as $\text{mL/kg/min}$, meaning millilitres of oxygen per kilogram of body weight per minute.

According to the lecture records, who hold the highest recorded $\text{VO}_2\text{ Max}$ values for men and women?

Men: Oskar Svendsen ($97.5\,\text{mL/kg/min}$, Cycling)\nWomen: Joan Benoit ($78.6\,\text{mL/kg/min}$, Marathon Running)

What chronic adaptation occurs within skeletal muscle mitochondria as a result of aerobic training?

Mitochondria (the aerobic powerhouses that produce ATP) increase in both size and number, enhancing the muscle's ability to produce energy aerobically.

Why do resting heart rate ($\text{HR}$) and resting respiratory rate ($\text{RR}$) decrease as chronic adaptations to aerobic training?

The heart and lungs become more efficient. Due to cardiac hypertrophy and increased ventricular filling, stroke volume increases, allowing the heart to deliver adequate oxygen with fewer beats per minute. Similarly, increased tidal volume and gas exchange efficiency allow the lungs to deliver required oxygen with fewer breaths per minute.

Based on this anatomical comparison, which heart belongs to the trained athlete and what does this mean for stroke volume?

Heart (a) on the left represents the trained athlete (e.g., swimmer's heart). It displays cardiac hypertrophy with an enlarged left ventricle, which produces a significantly higher stroke volume ($\text{SV}$) per contraction, enabling a lower resting heart rate.

How can a trained individual maintain the same cardiac output ($22{,}000\,\text{mL/min}$) during exercise as an untrained individual despite having a lower heart rate ($150\,\text{bpm}$ vs $195\,\text{bpm}$)?

The trained individual compensates for the lower heart rate by having a significantly higher stroke volume ($147\,\text{mL/beat}$ vs $113\,\text{mL/beat}$) due to cardiac hypertrophy, greater ventricular filling time, and stronger contractions ($Q = \text{HR} \times \text{SV}$).

In this graph of immediate heart rate response to training, which trace represents the trained athlete and why?

The blue (lower) trace represents the trained athlete. The trained athlete maintains a lower resting heart rate ($\sim 54\text{--}60\,\text{bpm}$ vs $\sim 70\text{--}72\,\text{bpm}$), a lower heart rate during exercise ($\sim 134\,\text{bpm}$ vs $\sim 150\text{--}155\,\text{bpm}$), and recovers back to resting levels much more rapidly post-exercise.

Jennifer is a $30$-year-old female. What is her calculated Maximum Heart Rate ($\text{MHR}$)?

$$\text{MHR} = 220 - \text{Age} = 220 - 30 = 190\,\text{bpm}$$

Why did Jennifer's resting heart rate decrease from $72\,\text{bpm}$ to $61\,\text{bpm}$ after $10$ weeks of training?

Her heart underwent chronic cardiovascular adaptations, including cardiac hypertrophy of the left ventricle and increased stroke volume ($\text{SV}$). Because her heart can pump more blood per beat, it requires fewer beats per minute to deliver the same amount of oxygen at rest.