Effects of RF on connective tissues (ligaments and tendons) have been shown in many studies (not going back quite as far as temperature or blood flow).

Most of the studies are for ‘chronic’ or ‘longstanding’ conditions:

• Silverman 1964
• Lehmann, Masock, Warren, Koblanski 1970
• Bricknell & Watson 1995
• Draper et al. 2002
• Peres, Draper, Knight, Ricard 2002.
• Brucker et al. 2005
• Giombini et al. 2007
• Mitchell, Trowbridge, Fincher, Cramer 2008
• Touchberry et al 2008
• Incebiyik, Boyaci,  Tutoglu 2015

Costantino et al. 2005 compared 448khz RF to laser and cryotherapy in acute Achilles, patella and lateral epicondyle tendinopathy.  They found RF was equal to either of the other interventions in the acute phase.