I have worked out a solution or at least a direction for me to head in. :)) @ripulkr and @boonebgorges gave me the idea of using a MySQL database and the use of tables to store the user’s data and their meta data.
I jumped on the WPdatatables plug-in which allowed me to easily use MySQL queries to the WordPress database (WPDB). I then created a table within the WPDB and created columns for the fields I wanted like height, weight, length. I also have a couple of other columns in the table to associate the record number and the user id.
WPdatatables also has an add-on for Gravity Forms so it was simple for users to fill out a form to submit data direct to the table. I then create a page for the users showing the WPDB table for them to only see their entries. It has a reports and chart feature too. :))
WPdatatables full use of MySQL queries allows me to join tables within the WPDB which makes it nice to be able to match up and show their user data too.
I’m pretty happy with how it works and its potential.
A very high level explanation but would be happy to explain further if needed. :))