Fig. 1.

Random synergies were generated from an exponential distribution (Wo) and used to calculate muscle activations with and without biomechanical and task constraints. With biomechanical and task constraints, muscle activations (a) were calculated using a musculoskeletal model to execute an isometric force task and were constrained to the specified synergies. Without biomechanical or task constraints, a random matrix of synergy activations, C, was generated from an exponential distribution, and activations were solved for as a = Wo × C. In both cases, matrix factorization algorithms were used to calculate the estimated synergies from the muscle activations. The synergies estimated by the matrix factorization algorithms were then compared with Wo, the specified synergies.