Postactivation potentiation biases maximal isometric strength assessment

Area of Science:

• Exercise Physiology
• Biomechanics
• Human Performance

Background:

• Postactivation potentiation (PAP) is a physiological phenomenon where a brief period of high-intensity muscle activity enhances subsequent voluntary muscle contractions.
• Maximal voluntary isometric contractions (MVCs) are commonly used to assess maximal strength, often involving multiple repetitions.

Purpose of the Study:

• To investigate the influence of PAP on maximal isometric strength assessment protocols.
• To determine if a preceding MVC affects subsequent strength measurements within standard assessment intervals.

Main Methods:

• Twenty-three healthy males performed two 5-second MVCs with a 180-second rest interval.
• Measurements included isometric peak torque (IPT), time to peak torque (tPTI), contractile impulse (CI), electromyographic root mean square (RMS), and rate of torque development (RTD).

Main Results:

• The second MVC showed significant increases in IPT, RTD, and RMS compared to the first MVC.
• Time to peak torque (tPTI) significantly decreased during the second MVC.
• These findings indicate a clear PAP effect influencing strength assessment variables.

Conclusions:

• A single MVC induces PAP, significantly enhancing strength-related variables in a subsequent MVC performed 180 seconds later.
• Failure to account for PAP can lead to overestimation of maximal isometric strength and related measures.
• This highlights the importance of considering PAP in strength testing protocols.