Scotland on Sunday reports that at Borders General Hospital, close to Glentress near Peebles, at least 10 casualties are treated every weekend as a result of injuries incurred while downhilling.
20,000 MTBers ride on Forestry Commission trails every week, but some are too inexperienced to ride the often technical trails, the more hairy of which have jumps and drop-offs that should not be ridden by DH novices.
Because of the rising number of injuries the Forestry Commission has ordered an inquiry and so has Belford Hospital near Fort William.
'Fort Bill' is the venue, later this month, for the UCI MTB World Cup.
A spokeswoman from Belford Hospital told Scotland on Sunday: "Staff have noticed they are getting more and more mountain-bike-related injuries. As a result they have taken someone on to conduct an audit of outdoor sports injuries."
Scottish Cycling's Colin Renton said: "If you are a beginner skier you wouldn't tackle a black run. The basics should be taught before people are allowed on serious mountain biking tracks."
The safety review is being undertaken by John Ireland, a Forestry Commission official involved in MTB trail construction for more than 20 years.
An A&E source at Borders General Hospital said: "People are wearing helmets, but even this is not giving them enough protection when they are hurtling down a track."
Risk compensation theorists would argue that the wearing of full-face helmets and body armour gives some DH cyclists a false sense of security, fooling them into thinking their protective equipment will protect them in all eventualities and therefore they can ride faster than their true abilities would suggest.
Scotland on Sunday reports that some of the injuries sustained recently have been spinal injuries.
Paul Taylor, a 35-year-old from Aberlour, is now paralysed from the chest down after a crash on a DH course near Fochabers last year. He was a recreational mountain bike rider, not a downhiller.
He said: "I tried to make it as safe for myself as I could by wearing a proper safety helmet - ordinary cycle helmets won't do. But when I came off, my head was OK but I injured my spine."