If a 75 kg person pedals a Monarch leg ergometer at 50 rpm, how much resistance is needed to work at a level of 11 METs?
To determine the resistance needed to work at a level of 11 METs on a Monarch leg ergometer, we need to understand a few key concepts and formulas.
1. METs: MET stands for metabolic equivalent of task and is a unit used to estimate the energy expenditure of physical activities. One MET is equivalent to the energy expended while sitting at rest, which is approximately 3.5 milliliters of oxygen per kilogram of body weight per minute (ml/kg/min).
2. Energy Expenditure: The energy expenditure can be calculated using the formula:
Energy Expenditure (METs) = Oxygen Consumption (ml/kg/min) / 3.5
3. Power Output: The power output required to pedal the leg ergometer can be calculated using the formula:
Power Output (watts) = Resistance (watts) * Cadence (rpm) * 6.12
Now, let's calculate the resistance needed to achieve 11 METs on the Monarch leg ergometer:
Step 1: Calculate the Oxygen Consumption in ml/kg/min:
Oxygen Consumption = METs * 3.5
Oxygen Consumption = 11 * 3.5 = 38.5 ml/kg/min
Step 2: Convert Oxygen Consumption to Power Output in watts:
Power Output = Oxygen Consumption * 75 kg (body weight) * 6.12
Power Output = 38.5 * 75 * 6.12 = 17715 watts
Step 3: Calculate the Resistance needed to achieve the required Power Output:
Resistance = Power Output / (Cadence * 6.12)
Resistance = 17715 / (50 * 6.12) ≈ 57.9 watts
Therefore, to work at a level of 11 METs on a Monarch leg ergometer at a cadence of 50 rpm, approximately 57.9 watts of resistance is needed.