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.