A bicep tendon is a band of fibrous tissues which has the property of being tough as well as flexible. It can withstand tension due to its flexibility. A bicep tendon tear can occur at two places, either at the elbow or at the shoulder. Bicep tear occurring at the shoulder is more common. 90% of the tears happen at the shoulder. Main reasons being over-head weight lifting, not warming up properly before any heavy physical activity, smoking too much, and age. Use of steroids is harmful as well; they lead to various disorders such as deficiency in sperm count, impotency and infertility. Moreover, they may lead to dysplasia of collagen fibrils, which can decrease the tensile strength of tendon, thus causing the bicep tendon to tear. These tears weaken your arm to an extent that 30% of your flexural strength and 40% of your supination strength decreases.
A complete bicep tear takes longer than a partial bicep tear to heal. Complete tears may require a bicep tendon surgery, after which it takes 6-9 months to recover completely. Keeping the arm immobile by use of a sling, putting no strain on the bicep, and light exercises to prevent forming of scar tissue are necessary in the initial six weeks post-surgery. In the next six weeks, light weight strengthening exercises can be done as recommended by your doctor. But putting strain on your bicep with activities such as driving a car or carrying bags must be avoided. In last 3 months of your recovery period, muscle strengthening exercises are a crucial part of your recovery and must be done as prescribed by your orthopaedic surgeon. On the other hand, a partial bicep tear takes 4-6 months to heal properly, but it may take longer if no precautions are made.
There are several tips given by well-known physical experts that will help you avoid a bicep tendon tear. These include warming up before your workout by dynamically stretching your muscles to ensure proper elongation and contraction, controlled movement of your arms when carrying weights (which means no swinging or jerking of the weight-carrying arm), finishing your workout with some static stretching and myofascial massage, and keeping yourself hydrated which is essential for strengthening and repairing your muscle fibers.
Here is a detailed infographic to answer your questions about bicep tendon tears: