Question

The physical fitness of athletes is measured by \(^{u} V_{\mathrm{O}_{2}} \max _{2}^{\prime \prime}\) 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 by an average man who weighs 185 lbs and has a \(V_{\mathrm{O}_{2}}\) max reading of 47.5 \(\mathrm{mLO}_{2} / \mathrm{kg}\) body mass/min. (b) If this man lost \(20 \mathrm{lb},\) exercised, and increased his \(V_{\mathrm{O}_{2}}\) max to 65.0 \(\mathrm{mL}\) O \(_{2} / \mathrm{kg}\) body mass/min, how many mL of oxygen would he consume in 1 \(\mathrm{hr}\) ?

Short answer

Initially, the man weighs 185 lbs, which converts to \(Weight_{kg} = \frac{185}{2.205} \approx 83.9kg\). The volume of oxygen consumed in 1 min is \(Volume_{1min} = 47.5 \cdot 83.9 \approx 3985.25 mL\). After losing 20 lbs, the new weight is \(New Weight_{kg} = \frac{185 - 20}{2.205} \approx 74.8 kg\). With a \(V_{O_2}\) max of 65.0 \(\mathrm{mLo}_{2} / \mathrm{kg}\), the volume of oxygen consumed in 1 min is \(Volume_{new1min} = 65.0 \cdot 74.8 \approx 4862.0 mL\), and in 1 hour, the volume is \(Volume_{1hr} = 4862.0 \cdot 60 \approx 291720 mL\).

Step-by-step solution

Convert weight to kg

We need to convert the man's weight from lbs to kg, as the \(V_{O_2}\) max is given in \(mL \cdot O_2 / kg \cdot min\). We are given: - Initial weight: 185 lbs - Weight loss: 20 lbs First, let's find the initial weight in kg: \(Weight_{kg} = \frac{Weight_{lbs}}{2.205}\)

Calculate the volume of oxygen consumed in 1 min initially

We are given that the \(V_{O_2}\) max of the man initially is 47.5 \(\mathrm{mLO}_{2} / \mathrm{kg}\) body mass/min. Now we can use the initial weight in kg, obtained in Step 1, and the \(V_{O_2}\) max formula to find the volume of oxygen consumed in 1 minute: \(Volume_{1min} = V_{O_2} \cdot Weight_{kg}\)

Calculate the weight after the weight loss

Now we can find the man's weight after losing 20 lbs. This new weight will be used to calculate the volume of oxygen consumed after increasing the \(V_{O_2}\) max: \(New Weight_{kg} = \frac{Initial Weight_{lbs} - Weight Loss_{lbs}}{2.205}\)

Calculate the volume of oxygen consumed in 1 hr with the increased \(V_{O_2}\) max

We are given that the new \(V_{O_2}\) max of the man after weight loss and exercising is 65.0 \(\mathrm{mLo}_{2} / \mathrm{kg}\) body mass/min. Now we can use the new weight in kg, obtained in Step 3, and the new \(V_{O_2}\) max formula to find the volume of oxygen consumed in 1 minute: \(Volume_{new1min} = New V_{O_2} \cdot New Weight_{kg}\) Now, to find the volume of oxygen consumed in 1 hour, we need to multiply the volume consumed in 1 minute by the number of minutes in an hour: \(Volume_{1hr} = Volume_{new1min} \cdot 60\)

Key concepts

VO2 max

VO2 max represents the maximum volume of oxygen that the body can utilize during intense exercise. This measurement is often used to gauge physical fitness, especially in endurance sports. It is expressed in milliliters of oxygen per kilogram of body weight per minute (mL O₂/kg/min).
VO2 max tests are generally conducted using treadmill or bicycle ergometer exercises to incrementally increase the intensity until exhaustion.
For instance, an average man's VO2 max might be around 45 mL O₂/kg/min, while elite athletes can exceed 80 mL O₂/kg/min.

• Why is VO2 Max Important?
  A higher VO2 max indicates greater cardiovascular fitness and endurance capabilities. It reflects how well your heart and lungs supply oxygen to your muscles during exercise.
• Can VO2 Max Be Improved?
  Yes, through regular aerobic exercises like running, swimming, and cycling. Strength training and interval workouts can also help.

exercise physiology

Exercise physiology involves the study of how the body's systems respond to physical activity. It explores how exercisers can improve their performance, achieve better health, and understand the mechanisms behind their body's responses to activity. Key topics within exercise physiology include:

• Cardiovascular System: As you exercise, your heart pumps more blood to supply muscles with oxygen and nutrients. This improved circulation enhances endurance.
• Respiratory System: Breathing rate increases to bring more oxygen into the bloodstream, supporting increased energy demands.
• Muscle Adaptation: Regular exercise induces changes in muscle fibers, enhancing strength and efficiency over time.

Exercise physiology teaches us about the body's stress responses and adaptations from exercise, allowing athletes to fine-tune their training for optimal results. Understanding these principles can support both fitness enthusiasts and professional athletes in reaching their performance goals.

unit conversion

Unit conversion is essential in exercise science, where measurements often need changing to understand data points correctly. When it comes to oxygen consumption, you might have to convert measurements between different units, such as pounds to kilograms for weight or liters to milliliters for volume. Here's how to convert weight from pounds to kilograms, a common necessity in VO2 max calculations:
Divide the weight in pounds by 2.205:\[Weight_{kg} = \frac{Weight_{lbs}}{2.205}\]Another common conversion in exercise physiology is minutes to hours for calculating total oxygen consumption over a session or event:Multiply the number of minutes by the rate of oxygen consumption per minute to achieve the total volume over that period. For example:\[Volume_{1hr} = Volume_{1min} \times 60\]Effective conversion practices ensure precision and accuracy in calculations and enhance understanding of physiological assessments and athletic performance.