What you need to bring
For the longer tours (2 to 4 hours total time) you will need to carry water and food (energy bars, etc) in a suitable backpack. For the warmer months of the year please bring a running cap. Your guide will be carrying a mobile phone and maps to share with you during the tour. Trail running shoes are a bonus, but most routes can be safely negotiated with a good pair of road running trainers.
Beginners Guide to Trail Running - Great piece from TrailRunner Magazine in the US.
http://www.trailrunnermag.com/article.php?id=186&cat=5 and one from Runner's World US edition...http://www.runnersworld.com/cda/microsite/0,8032,s6-238-511-0-0,00.html. For a general running guide visit http://dealnews.com/pages/articles/beginners-guide-running/ (Jack - thank you for your recommendation).
Useful sites to visit...
Sa Milana (Alaro running club, recently crowned champions of the Balearics) - a great place to get a feel for what is happening in Mallorcan running http://samilana.blogspot.com/
Elitechip. This is the official site for entering all the mountain races, marathons and triathlons on the island. http://www.elitechip.net/index.php?zwshow=&zwlng=en
Best running shop on the Island - easy to get to on the Palma ring road (Soller exit) - Benji has a great stock of trail shoes, gear and nutrition.
SeeMallorca. The leading online magazine and destination guide for Mallorca, featuring news, events and reviews for the discerning traveller.
Great book that will make you want to run and run and run and...
Council of Mallorca promotion of Drystone Route (GR221) http://www.conselldemallorca.net/?id_section=3198&id_parent=491&id_class=2992 (Spanish language, the English version is not available at the moment)
The walking bible of Mallorca from Cicerone http://www.amazon.co.uk/Walking-Mallorca-Classic-Mountain-Cicerone/dp/1852844884/ref=sr_1_1?ie=UTF8&qid=1321288837&sr=8-1 Also a guide to the Tramuntana Drystone Route GR221 http://www.amazon.co.uk/Trekking-Through-Mallorca-Drystone-Cicerone/dp/1852844957/ref=sr_1_1?s=books&ie=UTF8&qid=1321289083&sr=1-1
We like this map series http://www.amazon.co.uk/Mallorca-Tramuntana-Central-Gr11Maphiki/dp/8480903589/ref=pd_bxgy_b_text_b
Print 