The aim of this study was to investigate the relationship between Performance of Upper Limb (PUL) and Jebsen–Taylor Test (JTT) to assess and monitor upper limb function progression in patients with muscular dystrophy. Thirty patients diagnosed with Duchenne muscular dystrophy, limb-girdle muscular dystrophy, Becker muscular dystrophy, myotonic dystrophy Type 1, and fascioscapulohumeral dystrophy were submitted to the shoulder, elbow, and wrist domains of PUL, and to JTT subtests. Spearman tests investigated the relationships between PUL and JTT total scores and domains. Correlations were classified as strong (r ≥ 0.70), moderate (0.40 ≤ r < 0.70), or weak (r ≤ 0.40). There were strong correlations between the PUL and JTT total scores (r = −0.706). Although JTT measures time and PUL provides kinesiologic scores, these measures were related. Therefore, muscle synergies, which control the compensatory movements and motor functions involving mainly shoulder, elbow, wrist, and finger movements, are related to timed performance in patients with muscular dystrophies.