Joint motion

• Factors affecting joint range of motion (ROM)

  • Age: ROM decrease

  • Gender: F>M

  • Obesity: ROM decrease

  • Two-joint muscle effect

Muscle strength: Muscle maximum voluntary contraction (MVC)

• Static (isometric) strength [AIHA Guidelines]

  • Instruction: to reach the force in 2 s and hold it for about 3 s, to avoid high rate of force development

  • Band-width-filter the data and record peak/3 s avarage

  • 2 min rest

  • Standardization of procedure

  • No coercion, no competition

  • Minimize environmental distractions

  • Record subject attributes

  • Maintain controlled attributes

• Dynamic strength

  • More variability

  • Force direction dependent

  • Inertia dependent

  • Poor correlation with static strength

• Isoinertial strength

  • Constant acceleration

• Psycho physical strength

  • Subjective

• Factors affecting strength

  • Gender: F=(2/3)M

    • Lower extremity: F=0.8M

    • Upper extremity: F=0.5M, F=0.6M

    • Age: 60 yrs = 0.8 * 20 yrs

    • Weight: correlation between weight and strength r=0.3-0.5

    • Intercorrlations

      • Compatible muscle group: r=0.6

      • Incompatible muscle group: r=0.2

    • Training

      • 40% increase in 6 months

      • Correlation: best r=0.8

      • Anaerobic: protein and glycogen increase

      • Aerobic: capillary increase