Evaluation of alternating consecutive maximum contractions as an alternative test of neuromuscular function.

The standard strength test (SST) has been based only on sustained maximum forces, as well as on relatively large number trials needed to record the maximum forces (F) and their rate of development (RFD). The aim of this study was to extend our recent research on alternating consecutive maximum contractions (ACMC) performed by antagonist muscles. Instead of varying the frequency, we explored the properties of ACMC performed at the self-selected frequency and compared it with SST. Knee extensors and flexors were tested in 64 participants. Within-session reliability of F and RFD of the two muscles evaluated through a single ACMC trial proved to be high (ICC ≥ 0.8), as well as their concurrent validity regarding the SST (r ≥ 0.7). Mainly strong relationships (r > 0.50) with the maximum performance tests also suggested moderate-to-high external validity of ACMC variables. Finally, the same variables were also able to distinguish among the participants of different training and physical activity history (p < 0.05). Taken together, these data suggest that ACMC could have the properties of reliability, external validity, and sensitivity similar to SST. However, since ACMC still retains some important advantages over SST (e.g., being based on a brief and fatigue free procedure for testing two antagonistic muscles, and exposing the muscle and joint tissues to relatively low and transient forces), one could conclude that ACMC performed at the self-selected frequency could be developed into a test of muscle function that could be either alternative or complementary to the SST.