Functional training has its origins in rehabilitation. Physical therapists often use this approach to retrain patients with movement disorders. Interventions are designed to incorporate task and context specific practice in areas meaningful to each patient, with an overall goal of functional independence. For example, exercises that mimic what patients did at home or work may be included in treatment in order to help them return to their lives or jobs after an injury or surgery. Thus if a patient's job required repeatedly heavy lifting, rehabilitation would be targeted towards heavy lifting, if the patient were a parent of young children, it would be targeted towards moderate lifting and endurance, and if the patient were a marathon runner, training would be targeted towards re-building endurance. However, treatments are designed after careful consideration of the patient’s condition, what he or she would like to achieve, and ensuring goals of treatment are realistic and achievable.
Functional training attempts to adapt or develop exercises which allow individuals to perform the activities of daily life more easily and without injuries.
In the context of body building, functional training involves mainly weight bearing activities targeted at core muscles of the abdomen and lower back. Most fitness facilities have a variety of weight training machines which target and isolate specific muscles. As a result the movements do not necessarily bear any relationship to the movements people make in their regular activities or sports.
In rehabilitation, training does not necessarily have to involve weight bearing activities, but can target any task or a combination of tasks that a patient is having difficulty with. Balance (ability) training, for example, is often incorporated into a patient’s treatment plan if it has been impaired after injury or disease.
Functional training for sports 
Functional training, if performed correctly, will lead to better joint mobility and stability, as well as more efficient moment patterns. Improving these factors decreases the potential for an injury sustained during an athletic endeavor. performance in a sport. The benefits may arise from the use of training that emphasizes the body's natural ability to move in six degrees of freedom. In comparison, though machines appears to be safer to use, they restrict movements to a single plane of motion, which is an unnatural form of movement for the body and may potentially lead to faulty movement patterns or injury. In 2009 Spennewyn conducted research, published in the Journal of Strength and Conditioning Research which compared functional training to fixed variable training techniques, this was considered the first research of its type comparing the two methods of strength training.
Results of the study showed very substantial gains and benefits in the functional training group over fixed training equipment. Functional users had a 58% greater increase in strength over the fixed-form group. Their improvements in balance were 196% higher over fixed and reported an overall decrease in joint pain by 30%.
Functional training rehabilitation in patients after stroke 
Rehabilitation after stroke has evolved over the past 15 years from conventional treatment techniques to task specific training techniques which involve training of basic functions, skills and endurance (muscular and cardiovascular). Functional training has been well supported in evidenced based research for rehabilitation of this population. It has been shown that task specific training yields long-lasting cortical reorganization which is specific to the areas of the brain being used with each task. Studies have also shown that patients make larger gains in functional tasks used in their rehabilitation and since they are more likely to continue practicing these tasks in everyday living, better results during follow-up are obtained.
Standard resistance training machines are of limited use for functional training – their fixed patterns rarely mimic natural movements, and they focus the effort on a single muscle group, rather than engaging the stabilizers and peripheral muscles.
Some options include:
- Cable machines
- Medicine balls
- Bodyweight training
- Physioballs (also called Swiss balls or exercise balls)
- Resistance tubes
- Rocker and wobble boards
- Whole Body Vibration equipment (also called WBV or Acceleration Training)
- Balance disks
- Suspension system
In rehabilitation however, equipment is mainly chosen by its relevance to the patient. In many cases equipment needs are minimal and include things that are familiar and useful to the patient.
Cable machines 
Cable machines, also known as pulley machines, are large upright machines, either with a single pulley, or else a pulley attached to both sides. They allow an athlete to recruit all major muscle groups while moving in multiple planes. Cable machines also provide a smooth, continuous action which reduces the need for momentum to start repetitions, provide a constant tension on the muscle, peak-contraction is possible at the top of each rep, a safe means of performing negative repetitions, and a variety of attachments that allow great flexibility in the exercises performed and body parts targeted.
Components of a functional exercise program 
To be effective a functional exercise program should include a number of different elements, which can be adapted to an individuals needs or goals:
- Based on functional tasks directed toward everyday life activities.
- Individualized – a training program should be tailored to each individual. Any program must be specific to the goals of an individual, focusing on meaningful tasks. It must also be specific to the individual state of health, including presence or history of injury. An assessment should be performed to help guide exercise selection and training load.
- Integrated – It should include a variety of exercises that work on flexibility, core, balance, strength and power, focusing on multiple movement planes.
- Progressive – Progressive training steadily increases the difficulty of the task.
- Periodized – mainly by training with distributed practice and varying the tasks.
- Repeated frequently.
- Use of real life object manipulation.
- Performed in context-specific environments.
- Feedback should be incorporated following performance (self-feedback of success is used as well as trainer/therapist feedback).
- O'Sullivan, Susan B. (2007). Physical Therapy 5th Edition. glossary: F.A. Davis Company. p. 1335. ISBN 0-8036-1247-8.
- Cannone, Jesse. "Functional training". Retrieved 2007-08-26.
- Burton, Craig (2007). "What is Functional Resistance Training". Retrieved 2007-08-26.
- Spennewyn,K. 2008. Journal of Strength and Conditioning Research, January, Volume 22, Number 1. 
- Timmermans, A. A, Spooren, A. I. F., Kingma, H., Seleen, H. A. M. (2010). "Influence of Task-Oriented Training Content on Skilled Arm–Hand Performance in Stroke: A Systematic Review". Neural rehabilitation and neural repair 24: 219–224. doi:10.1177/1545968310368963.
- Blennerhassett, J., & Dite, W. (2004). "Additional task-related practice improves mobility and upper limb function early after stroke: A randomised controlled trial". Australian journal of physiotherapy 50: 858–870.
- "Upper extremity interventions", Evidence-based review of stroke rehabilitation