Complex sentence: In patients with ALS, it's been shown that distal motor latencies and slowing of conduction velocity worsened as the severity of muscle weakness increased in these patients, which is consistent with the axonal degeneration occurring in ALS patients.
Split into simpler sentences: In patients with ALS, it's been shown that distal motor latencies and slowing of conduction velocity worsened as the severity of their muscle weakness increased. Both symptoms are consistent with the axonal degeneration occurring in ALS patients.