Principles of Exercise


The scientific evidence demonstrating the beneficial effects of exercise is indisputable, and the benefits of exercise far outweigh the risks in most adults. For most adults, an exercise program including aerobic, resistance, flexibility, and neuromotor exercise training is indispensable to improve and maintain physical fitness and health. An exercise training program ideally is designed to meet individual health and physical fitness goals within the context of individual health status, function, and the respective physical and social environment[1].

Therapeutic exercise is one of the core skills upon which the profession of physiotherapy is based. By considering definitions of therapeutic exercise, physical activity, and exercise, it is possible to see that, although therapeutic exercise contains the components of both physical activity and exercise, it also provides a systematic exercise programme for remediation of impairments and improvement of function[2].

What is the difference between physical activity and exercise? Physical activity refers to the contraction of skeletal muscle that produces bodily movement and requires energy. Exercise is a physical activity that is planned and is performed with the goal of attaining or maintaining physical fitness. Physical fitness is a set of traits that allows an individual to perform physical activity[3].

Designing a therapeutic exercise programme

A programme may include a range of different types of exercise such as those for improving or preventing deterioration in aerobic capacity, muscle strength, power and endurance, flexibility or range of movement, balance, coordination, and agility. Although there are many different professionals involved in delivering advice on physical activity and exercise to various population groups, Physiotherapists are equipped with special skills to provide therapeutic exercise programmes. To be able to do this, a physiotherapist requires an understanding of the underlying disease process or pathology, exercise physiology, biomechanics, physical principles, and the evidence base supporting the area as well as an awareness of psychological o and safety issues. The physiotherapist must also be able to identify appropriate treatment goals in conjunction with the patient[4]. In general, all exercise training and sport sessions should start with a 10–15-min dynamic warm-up period followed by 20–60 min of exercise training. Finally, a 10-min cool-down period with less intensive activities and stretching should end the exercise training session. Between the training sessions, there must be enough time to recover.

Common training principles

Overload A system must be exercised at a level beyond which it is presently accustomed for a training effect to occur. The system being exercised will gradually adapt to the overload or training stimulus being applied, and this will go on happening as long as the training stimulus continues to be increased until the tissue can no longer adapt. The training stimulus applied consists of different variables such as intensity, duration, and frequency of exercise. It is important to give the system being exercised enough time to recover and only apply a training stimulus again when the system is no longer fatigued[4].

Specificity Any exercise will train a system for the particular task being carried out as the training stimulus. This means that, for example, a training programme including muscle strengthening will train the muscle in the range that it is working and the way that the muscle is being used, i.e. isometrically, concentrically, or eccentrically. It is important that any exercise to strengthen muscle targets the muscle range and type of muscle work specific to the task required. For example, riding a bicycle requires concentric knee extension from mid-to inner r,1I1ge, as the pedal is pushed down to propel the bicycle along. cyclist wishing to increase the strength of his quadriceps will need to tr.lin concentrically in mid-to inner range. Depending on the presenting problem, the required task should become part of the training programme at an appropriate stage[4].

Reversibility The beneficial effects of training begin to be lost as soon as training stops. This happens in a similar time frame as it takes to train the system[4].

Individuality Variation in response to a training programme will occur in a population as people respond differently to the same training programme. This response can be explained by the initial fitness level of the individual, their health status, and their genetic makeup. Training programmes should be designed to take this into account. Some individuals will have a predisposition to endurance training and some to strength training. Some will respond well to a training programme and others much more slowly. Those individuals with a lower fitness level before starting an exercise programme show improvement in fitness more quickly than those who are relatively fit before training begins. Some individuals with health conditions may not be able to work at the same kind of intensity as a healthy individual and so will take longer to achieve a training goal[4].

Motor learning To be able to teach and supervise an exercise programme effectively, the physiotherapist needs an understanding of how people learn motor skills. Motor learning is not just concerned with the acquisition of motor skills but also with how the individual interacts with the task to be learned and the environment. This uses perception or sensing, cognition, and motor processes. Learning a skill is a relatively permanent change in an individual and there are several stages that the person will go through before the skill is retained. Initially, a person may be unable to perform a task. With practice, o they will achieve the task but it will not be carried out efficiently. With further practice and feedback, the person will be able to carry out the task to a reasonable standard but they may forget how to do it if they do not do the task regularly. In the final stage the person I will carry out the task efficiently, in a skilled manner and will not U forget how to do the task. When teaching a patient an exercise, the physiotherapist should explain or demonstrate how to carry out the exercise, doing this as a whole if the exercise is simple or breaking a complex exercise into parts. When the patient is able to carry out the component parts, the exercise should be practiced as a whole. The patient needs to think about and practice the exercise. Both the physiotherapist and the patient should evaluate how well the exercise was performed and if the exercise task was completed. The physiotherapist should allow the patient a short time to evaluate their own performance, before providing feedback prior to subsequent practice. Practicing a skill (or exercise) in a varied manner, for example at different speeds or in different environments, will help with learning[4].

Safety Whenever an individual exercise, there is a risk that they may injure themselves. Safety factors are considered here in relation to the physiotherapist. the environment and the patient or person carrying alit the exercise[4].

Aerobic (cardiorespiratory endurance)capacity

The dose of exercise can be described using the so-called FITT factors, where FITT stands for Frequency, Intensity, Time, and Type of activity.[5] The same principle could be used endurance training to dose a load. It should be noted that some individuals may not respond as expected because there is appreciable individual variability in the magnitude of response to a particular exercise regimen. Furthermore, the FITT principle of exercise may not apply in certain cases because of individual characteristics (e.g., health status, physical ability, age) or athletic and performance goals. Accommodations to the exercise should be made for individuals with clinical conditions and healthy individuals with special considerations[1]. ACSM recommends to use the FITT method:[6]

Frequency (how often)

Exercise should be carried out 3-5 days a week.

Training three times a week produces significant training effects; however, training 5 days a week at a lower-intensity exercise may be more manageable for some people. A Little additional benefit is seen with more than five training sessions a week, and the risk of injury is increased. Training twice a week does not produce increases in VO2max; however, it may produce some functional changes and it is probably better than no exercise at all[4]. Moderate-intensity aerobic exercise done at least 5 d ∙ wk or vigorous-intensity aerobic exercise done at least 3 d ∙ wk or a weekly combination of 3–5 d ∙ wk of moderate and vigorous-intensity exercise is recommended for most adults to achieve and maintain health/fitness benefits[6].

Intensity (how hard)

Intensity can be monitored by heart rate in most patients, although some patients may have pathology or be on drug treatment that affects their HR response to exercise in which case HR cannot be used to monitor exercise intensity. Exercise is categorized into three different intensity levels. These levels include low, moderate, and vigorous and are measured by the metabolic equivalent of task (aka metabolic equivalent or METs[4]. The overload principle of training states exercise below a minimum intensity, or threshold will not challenge the body sufficiently to result in changes in physiologic parameters, including increased maximal volume of oxygen consumed per unit of time (VO2max)[6].

The Karvonen method, which takes into account resting can be used to calculate an individual's training HR band using the following calculation. A method of calculating the training heart rate, which is equivalent to the desired percentage VO2max. It involves adding a given percentage of the maximal heart rate reserve (maximal heart rate—resting heart rate) to the resting heart rate. The maximal heart rate is commonly assumed to be 220—age in years. Therefore, the following equation is used to calculate the training heart rate for a work rate equivalent to 75% VO2max: training heart rate = 0.75 max HRR + resting HR; where max HRR is the Maximum Heart Rate Reserve, and resting HR is resting Heart Rate. A target heart rate range for training is commonly set at values of between 50 and 85% of VO2max, i.e. 0.50 × max HRR + resting HR to 0.85 max HRR + resting HR[7]. Other methods you can look here.


In the absence of a heart rate, monitor people can monitor their own pulse to ensure that they are working at the correct intensity. Patients should be taught how to take their carotid pulse within the first 10 or 15 seconds of terminating exercise and multiplying up the beats counted by 6 or 4 respectively to provide beats per minute. Oxygen uptake can also be used to set exercise intensity, and intensity of 40-50% to 85% of the oxygen uptake reserve is recommended.

Measures of perceived effort and affective valence (i.e.the pleasantness of exercise) can be used to modulate or refine the prescribed exercise intensity. These measures include the Borg Rating of Perceived Exertion (RPE) Scales, OMNI Scales, Talk Test, and Feeling Scale[6].

Time (duration or how long)

A total of 20-60 minutes of continuous or intermittent aerobic activity a day should be performed. The activity can be divided into a minimum of lO-minute bouts throughout the day. The duration of training is dependent on intensity. Individuals starting at the lower end of the training band need to sustain exercise longer (30-60 minutes) to achieve training effects[4].

  • Type(mode or what kind)
  • Volume (amount)
  • Progression (advancement)
The video below summerizes FITT Principle
Strength training

Frequency -2-3 days a week.

Intensity -one set of 8-10 RM to volitional fatigue.

Duration -3 seconds for the concentric phase and 3 seconds for the eccentric phase of the activity (about 1 minute in total).

A general strengthening programme would include 8-10 exercises that target all the major muscle groups in the body[2].

In other points of view resistance training (RT) has been acknowledged as an effective method to improve muscular strength, power, and hypertrophy which are fundamental components of physical fitness related to the quality of life[10]. Research over the last few decades has investigated the effects of several acute training variables on maximal strength gains that influence the overall outcome of an RT program[11]. These RT variables include exercise order, the number of sets, repetitions, inter-set recovery periods, training intensity per muscle group, and total training volume.

Quantifying recovery rates and providing recommendations on RT frequency for strength gains is difficult and may vary between training status, sex, and muscle groups. Physical activity guidelines from leading organizations including the American College of Sports Medicine (ACSM)[12].recommend RT frequency of 2 to 3 days per week (days week− 1) for healthy adults. These frequency recommendations are however notional, derived from conjecture rather than robust scientific evidence. This lack of evidence weakens established recommendations regarding progressive RT loading and training volumes for improved muscular strength[13]. Several RT studies have reported that an RT frequency of 2 to 3 days week− 1 for previously untrained individuals[14]produces optimum strength gains. Feigenbaum and Pollock[15]suggest that a single set program of 15 repetitions performed at a frequency of 2 to 3 days week− 1 allows for sufficient regeneration, while still providing 80–90% strength gains of more frequent RT programs. Moreover, the authors suggest that each RT session should be comprised of 8 to 10 different exercises that target the major muscles. However, these recommendations are generalized and are provided for all subjects with varying health conditions and age ranges.RT studies frequently cited in scientific literature do not adequately describe the frequency for different population groups (untrained, trained, and well trained)[16].

However, a meta-analysis by Silva et al. [18] on adults over 55 years of age found no differences in strength when training 1, 2, or 3 days week− 1. The authors suggest that different combinations of acute RT variables might be equally valid in the strength development of healthy sedentary older adults. The only training variable that displayed any significant effect size (ES) for strength was training duration[17]. Grgic et al. [19] concluded that higher frequency could be used as a method of increasing total weekly training volume to promote muscular strength gains[18].


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