Manage changes in exercise carefully to help prevent injury
Injuries are most likely to occur during periods of increasing volume or intensity of exercise, or a change in exercise type.
Exercise imposes stress on many body systems: cardiorespiratory, musculoskeletal, neuromuscular & metabolic. Slow, steady changes together with sufficient recovery, will result in adaptation of these systems over time meaning your body becomes stronger, fitter and faster and reduces the risk of injury. A good rule is a maximum of 10% change in any exercise variable (volume, intensity, type of activity) in a week but this is not enough by itself to prevent injury for everyone.
NEVER IGNORE PAIN - if it occurs reduce exercise volume and/or intensity and then ramp up again slowly. If there is a recurring issue then seek out a physical therapist. Sports massage aims to prevent injuries and stop niggles turning into something longer term as well as facilitate injury recovery.