Units of Measure

Questions:

  1. How to quantify the maximum speed of an athlete? Velocity

  2. How would you expect how much lower body power that person produced while running? Jouls of power

  3. How quickly they accelerate from starting blocks? M/S²

  4. Total amount fo work they produce during 100 m sprint? Measurements of work and power

Metric Unit

  • the standard system of measurement by scientists

  • Easier to convert because of the based 10’s

  • used to express mass, length, and volume

  • Ex: Grams, Meters, Liters

Metric prefixes: Larger → Smaller unit move decimal right, Smaller → Larger move decimal left

  • mega - 1,000,000

  • kilo - 1,000

  • centi - .01

  • milli - .001

  • micro - .000001

  • nano - .000000001

  • pico - .000000000001

System International (SI) Unit

  • Standardized units of measurement

  • Every publication in exercise science, sports medicine, nutirtion

System for Human Exercise

  • Mass - Kg

  • Distance - m

  • Time - sec

  • Force - Newtons

  • Work - Jouls

  • Energy - Jouls

  • Power - Watt

  • Velocity - m/s

  • Torque - N(m)

    • Force is measure in torque inside a human body because all humans bodies motions are circular

    • only reason you cant complete the whole circle is becasue of flexibility

Gravity and Force

  • 1 N = 1 kg(m/s²)

    • Newton is the force needed to accelerate one kilogram at one meter per second every second

      • F = m(a)

    • A kilogram force is the force exerted on one kilgram of mass in earths gravitational field

      • 1KgF = 9.81 N

What is the force of a 60 kg person standing still on Earth:

What force is needed to lift a 100kg barbell:

  • Calculate how much stuff an athlete did during a workout through WORK

Calculating Joules and Work

  • J = kg (m²) / (s²)

  • W *J = force x distance

Ex: Lifting a 10 kg weight up a distance of 2m

Common Units use to express work and energy

  • Kilopond-meter - 1 kpm = 9.81J

  • Kilocalorie - 1 kcal = 4186 J or 4.186 kJ → 1 Kcal = 426.8 kpm

Estimating energy expenditure from work

  • EX) 100 kg man walks up 10 stairs that were 8 inches high (0.2m):

  • How many Kcals of energy is that?

Estimating energy expenditure from work

  • Our body is nowhere near 100% expenditure

  • only about 20-30%

What is the work done against grvatity if a 65kg perosn climbs a 15m high flight of stairs:

  • Now assume the subject wore a mask and used 47,775 Joules of energy to complete this task: How efficient was this person at using energy to complete this task?