Question

The physical fitness of athletes is measured by \({ }^{~} V_{\mathrm{O}_{2}}\) max, " which is the maximum volume of oxygen consumed by an individual during incremental exercise (for example, on a treadmill). An average male has a \(V_{\mathrm{O}_{2}}\) max of \(45 \mathrm{~mL} \mathrm{O}_{2} / \mathrm{kg}\) body mass/min, but a world-class male athlete can have a \(V_{\mathrm{O}_{2}}\) max reading of \(88.0 \mathrm{~mL} \mathrm{O}_{2} / \mathrm{kg}\) body mass/min. (a) Calculate the volume of oxygen, in mL, consumed in \(1 \mathrm{hr}\) by an average man who weighs \(185 \mathrm{lbs}\) and has a \(V_{\mathrm{O}_{2}}\) max reading of \(47.5 \mathrm{~mL} \mathrm{O}_{2} / \mathrm{kg}\) body mass/min. (b) If this man lost \(20 \mathrm{lb}\), exercised, and increased his \(V_{\mathrm{O}_{2}}\) max to \(65.0 \mathrm{~mL} \mathrm{O} / \mathrm{kg}\) body mass/min, how many \(\mathrm{mL}\) of oxygen would he consume in \(1 \mathrm{hr}\) ?

Short answer

(a) The total volume of oxygen consumed in 1 hour by an average man who weighs 185 lbs and has a \(V_{\mathrm{O}_{2}}\) max reading of 47.5 mL O2/kg body mass/min is approximately: 239,216.4 mL O2. (b) If the same man lost 20 lbs, exercised, and increased his \(V_{\mathrm{O}_{2}}\) max to 65.0 mL O2/kg body mass/min, he would consume approximately: 291,886.8 mL O2 in 1 hour.

Step-by-step solution

Convert body mass from lbs to kg

To convert body mass from lbs to kg, we need to use the following conversion factor: 1 kg = 2.20462 lbs. Let's convert the body mass of the average man from lbs to kg: \(m_{kg} = m_{lbs} \times \frac{1\ \mathrm{kg}}{2.20462\ \mathrm{lbs}}\) For the case of an average man with a weight of 185 lbs: \(m_{kg} = 185\ \mathrm{lbs} \times \frac{1\ \mathrm{kg}}{2.20462\ \mathrm{lbs}} \approx 83.9146\ \mathrm{kg}\)

Calculate the total oxygen consumed per minute

We can find the total oxygen consumed per minute by multiplying the body mass (in kg) with the \(V_{\mathrm{O}_{2}}\) max reading (in mL O2/kg body mass/min): \(O_2 = m_{kg} \times V_{\mathrm{O}_{2}}\ \mathrm{max}\) For the case of an average man with a \(V_{\mathrm{O}_{2}}\) max reading of 47.5 mL O2/kg body mass/min: \(O_2 = 83.9146 \ \mathrm{kg} \times 47.5\ \mathrm{mL\ O}_{2} \ / \mathrm{kg} ≈ 3986.94\ \mathrm{mL\ O}_{2} / \mathrm{min}\)

Calculate the total oxygen consumed in 1 hour

To find the total oxygen consumed in 1 hour, we need to multiply the oxygen consumed per minute by the number of minutes in an hour (60 minutes): \(O_{1hr} = O_2 \times 60\ \mathrm{min}\) For the case of an average man weighing 185 lbs and with a \(V_{\mathrm{O}_{2}}\) max reading of 47.5 mL O2/kg body mass/min: \(O_{1hr} = 3986.94\ \mathrm{mL\ O}_{2} / \mathrm{min} \times 60\ \mathrm{min} = 239216.4\ \mathrm{mL\ O}_{2}\)

Calculate the total oxygen consumed for the man after losing weight and increasing his \(V_{\mathrm{O}_{2}}\) max

First, let's convert the new body mass after losing 20 lbs to kg and find the new total oxygen consumed per minute for the man: New body mass: \(m_{new\_kg} = (185\ \mathrm{lbs} - 20\ \mathrm{lbs}) \times \frac{1\ \mathrm{kg}}{2.20462\ \mathrm{lbs}} \approx 74.8428\ \mathrm{kg}\) New total oxygen consumed per minute: \(O_{new} = m_{new\_kg} \times V_{\mathrm{O}_{2}}\ \mathrm{max}\) For the case of the man with a new weight and a \(V_{\mathrm{O}_{2}}\) max reading of 65.0 mL O2/kg body mass/min: \(O_{new} = 74.8428\ \mathrm{kg} \times 65.0\ \mathrm{mL\ O}_{2} / \mathrm{kg} ≈ 4864.78\ \mathrm{mL\ O}_{2} / \mathrm{min}\) Next, let's calculate the total oxygen consumed in 1 hour for the man after losing weight and increasing his \(V_{\mathrm{O}_{2}}\) max: \(O_{new\_1hr} = O_{new} \times 60\ \mathrm{min}\) \(O_{new\_1hr} = 4864.78\ \mathrm{mL\ O}_{2} / \mathrm{min} \times 60\ \mathrm{min} = 291886.8\ \mathrm{mL\ O}_{2}\)

Present the final answers

(a) The total volume of oxygen consumed in 1 hour by an average man who weighs 185 lbs and has a \(V_{\mathrm{O}_{2}}\) max reading of 47.5 mL O2/kg body mass/min is approximately: 239,216.4 mL O2 (b) If the same man lost 20 lbs, exercised, and increased his \(V_{\mathrm{O}_{2}}\) max to 65.0 mL O2/kg body mass/min, he would consume approximately: 291,886.8 mL O2 in 1 hour

Key concepts

Oxygen Consumption

Oxygen consumption is a measure of how much oxygen your body uses during physical activity. It is crucial for assessing athletic performance and overall cardiovascular fitness. VO2 max represents the maximum volume of oxygen your body can consume per minute per kilogram of body weight. This metric is a key indicator for endurance sports as it reflects how well the heart and lungs can deliver oxygen to the muscles.
During exercise, our muscles require more oxygen to produce energy. This increased demand is met by enhancing oxygen intake through breathing, and efficient delivery through blood circulation. Fitness improvements often result in higher VO2 max scores, symbolizing a more efficient oxygen consumption system.
Understanding oxygen consumption helps athletes and coaches design effective training programs that enhance performance and endurance.

Body Mass Conversion

Body mass conversion is a simple yet vital calculation needed to accurately assess fitness parameters like VO2 max. Body weight is often expressed in pounds, especially in the US, but VO2 max requires weight in kilograms.
The conversion between pounds and kilograms is done using the factor:

• 1 kg = 2.20462 lbs

For example, if an individual weighs 185 lbs, their weight in kg would be: \[ m_{kg} = \frac{185\, \text{lbs}}{2.20462} \approx 83.91 \text{ kg} \]
Converting weight is essential for calculating oxygen consumption accurately, providing true comparisons across different individuals and their fitness levels. Without this conversion, the results of VO2 max could be misleading and affect training outcomes or health assessments.

Exercise Physiology

Exercise physiology is the study of how the body responds and adapts to physical activity. It explores how muscles, cardiovascular systems, and energy systems work together to perform any physical task.
Increasing autophagy during exercise is vital for improving oxygen delivery and consumption. When individuals work out, the ardent demand for oxygen helps strengthen the heart and muscles, increasing endurance and power.
The body's adaptation, including increased capillaries, mitochondrial density, and lung capacity, can visibly improve VO2 max outcomes, indicating a well-functioning athletic system.

• Regular training might involve aerobic exercises, enhancing the body's ability to consume oxygen effectively.

Understanding exercise physiology helps optimize training regimens tailored to improve specific performance metrics like VO2 max.

Athlete Physical Fitness

Athlete physical fitness revolves around achieving high levels of cardiorespiratory, muscular, and overall body conditioning. VO2 max is a central measure within this framework as it quantifies an athlete’s aerobic capabilities.
Being physically fit means having the stamina, strength, and flexibility necessary for high performance in sports and daily activities.

• Athletes with high VO2 max have better oxygen efficiency which translates to enhanced endurance.
• Weight management, muscle strength, and agility are also pieces of the fitness puzzle.

Regular evaluations and fitness tests help athletes track their progress, optimize their training routines, and set realistic goals that enhance their competitive edge and well-being.