Key Points for Testing Isometric Strength, RFD and Power

Maximal Isometric Testing

  • Provides a standardized and technique-independent-measure of maximal muscle strength
  • Sample at a minimum of 1000 Hz
  • Perform at least three efforts separated by 20-30 s, and provide familiarization repetitions
  • Control the joint angle carefully
  • Watch for compensations during multi-joint assessments
  • Standardization is the key for reliability

Mechanical Power Testing

  • The vertical jump is an idea movement for assessing lower body mechanical power abilities
  • Upper body mechanical power can be assessed with explosive push ups on force plates or using pull up force handles
  • Perform 3 to 5 repetitions separated by 20 s with a steady baseline between each repetition
  • Take the trial with the highest value
  • Choose mean power over peak power as it characterizes a larger portion of the movement
  • Consider characterizing performance in the movement of interest (e.g. jump height) as a measure of muscle power

Rate of Force Development (RFD) Testing

  • Sampling frequency at least 1000 Hz
  • Ensure instructions are given to produce force as fast and hard as possible
  • Ensure enough repetitions are performed for reliability purposes (minimum 5 but 10 is better)
  • Contractions do not have to be taken to maximum force
  • Metrics include: early RFD, late RFD, sequential RFD, maximal RFD, contractile impulse
  • Contractile impulse is proportional to the angular velocity of the limb should the limb have been permitted to move
  • In the Seminar below, we will look at different approaches for strength and power testing.