VM runing in vSphere 4.1 environment is either Virtual Hardware version 4 or virtual hardware 7 VMs.
both of those hardware version is compatible with vSphere 5.5 environment, so if you could present datastore being used by your ESXi 4.1 host to ESXi 5.5 host too and power off VMs from current host, remove them from inventory and register them into ESXi 5.5 host. Power them on. If you want to upgrade hardware version, while VM is off on new host, first upgrade hardware version and then power them on.