A good activity program should entail both aerobic training, small bursts of anaerobic high-intensity activity and strength exercise. Aerobic activity consists of cycloergometer, recline ergometer, or arm ergometer (the choice depending on the presence of orthopedic problems). Based on the fact that a smaller muscle mass is used in cycling exercise to attain the same metabolic energy expenditure of walking [25] with a greater metabolic stress and energy requirement per unit of contracting muscle [38], it has been evidenced [26] that walking is a convenient mode of exercise, compared to cycling. Walking permits in fact to attain any given energy expenditure at a comparatively lower average heart rate (or in a shorter time), with lower lactic acid blood concentration and higher fat oxidation. In practice, by some reckoning from these data comparing the metabolic responses of the two modalities, to obtain the energy expenditure of 250 kcal with a bout of 25-min activity, cycling should be performed at an intensity requiring an average heart rate of about 160 b/min with 3 g of lipids oxidation, whereas it will be sufficient to walk at intensity requiring an average heart rate of about 130 b/min, with over 11 g of lipid oxidation. Under this perspective, for obese individuals, inherently limited in their work capacity, it is very attractive to devise forms of physical activity enabling the attainment of a considerable energy expenditure by preference promoting substantial fat oxidation with the lower subjective perception of effort and exercise intensity, which could ultimately allow a better tolerance and adherence to physical activity protocols.

The optimal duration of exercise is 30 min, or longer, to optimize fat oxidation [1].

The effects of regular aerobic and resistance training on cardiovascular risk and general well-being are clearly demonstrated [35–37, 39], and increasing both intensity and duration exerts a beneficial effect. Patients who are able to exercise to a level of 7.9 METs have lower rates of events. In our population, in a consecutive sample of 3,728 obese patients, 732 were not able to perform a treadmill exercise test; of the remaining 2,996 the vast majority reached a peak exercise level of less than 7.9 METs, and only 620 patients (21 %) exceeded that threshold. Exercise is safe and the risk of a cardiovascular event is very low in a cardiovascular rehabilitation setting [42–46]. Current guidelines recommend intensity range between 3 and 6 METs on most days of the week: this goal can be achieved by walking 30 min every day or walking 60 min every second day. Cycling also represents a good exercise mode for obese subjects: for those who complain of osteoarticular pain while standing or venous insufficiency, it may represent the first choice modality. Cycling in recline position is a safer mode of exercise, providing back support and relatively lower loading at knee level.

Target heart rate during exercise has to be based on resting heart rate and peak heart rate during a symptom-limited treadmill stress test. We use the formula Target HR = Resting HR + (Peak HR–Resting HR) × 0.7, i.e., resting heart rate + 70 % of the chronotropic reserve that level of effort is generally associated with a “comfortable fatigue” sensation.

Patients also undergo a strength exercise program that is individualized considering patient’s characteristics. They work for 45–60 min on a daily basis at low intensity; the main purposes of this activity are to increase muscle strength, to balance muscle tone and mass, to reach a good equilibrium between flexor and extensor muscles, to improve joint stability and mobility, to improve motor coordination, to improve body and motor patterns, and to relax both physically and psychologically.

A significant improvement in quality of life, as well as in life expectancy, can be achieved independently of weight change only because of regular exercise [5]. Cardiac rehabilitation causes a significant improvement in the cardiovascular risk profile at all levels of BMI, independently of weight loss. The issue whether it is weight or fitness that makes the difference has been addressed by Lee and coworkers [27]: they studied over 14,000 men and found that, for each 1-MET improvement, a 19 % decrease in cardiovascular mortality was present, regardless of BMI or percent body fat change. Obese subjects who exercise regularly have a lower risk for metabolic abnormalities and their consequences than sedentary obese and represent the so-called fat-but-fit phenotype. Considering that obesity is a chronic disease and therefore a complete recovery is not foreseeable, we can try to adopt the same concepts that we use when we treat other chronic conditions such as hypertension or diabetes and set the “fat-but-fit” phenotype as a new target for obese subjects [55].

Moreover caution on promoting unconditional weight loss may be safe, since obesity has a complex relationship with all-cause mortality, and, in patients with congestive heart failure or coronary artery disease, the presence of obesity is associated with lower mortality when compared to normally weighting patients [24]. Therefore, our target, even if most of the features that characterize the obesity cardiomyopathy can be reversed by means of weight loss, should mainly focus on the adoption of an active lifestyle which has a great impact on the prognosis of obese patients. For a weight-loss intervention to be successful, a negative energy balance must be attained; in this view, energy expenditure in the form of physical activity is an important part in the management of obesity for losing weight and reducing associated risk factors for chronic disease. Many formulas are recommended, principally in the form of “moderate-intensity exercise” typically defined as 55–70 % of maximum heart rate, 30–60 min day, and 5–7 days a week [29, 30, 33]. Less is known about advisable heavier intensities of exercise. With regard to this last topic, it has been observed that bouts of exercise beyond anaerobic threshold added to a program of aerobic activity significantly increase the release of GH at a more extent than aerobic activity alone during physical exercise. This may be of some interest considering that GH is known as one of the most active substance able to ameliorate the ratio fat mass/fat-free mass [52].

Moreover, aerobic activity alone promotes a modest lowering of fat mass, a reduction in circulating nonesterified fatty acids, and an increase in circulating lactic acid, with a reduction in insulin resistance for glucose. Bouts of added anaerobic exercise to an aerobic program promote a significant more important lowering in fat mass, an increase in circulating nonesterified fatty acids, a decrease in circulating lactic acid, and no modification in insulin resistance for glucose.

The drop in circulating nonesterified fatty acids after aerobic training may be the result of an imbalance between a slow mobilization of fatty acids from adipose tissue and their rapidly increased extraction by skeletal muscle so demonstrating an increased oxidative capacity by the muscle. At the same time, the increase in lactic acid may be linked to the modified utilization of glucose due to the improvement in insulin sensitivity for it. The increase in circulating nonesterified fatty acids after aerobic plus anaerobic training may be due to an increased flow of substances with lipolytic activity after anaerobic stress (like GH, catecholamines, etc.) which causes an excessive mobilization of lipids that probably exceeds their dynamic utilization.

These observations may indicate the opportunity to initially prescribe aerobic with bouts of anaerobic training to decrease fat mass and subsequently aerobic training alone to maintain the weight loss and ameliorate the metabolic profile.

The exercise scheme “aerobic plus anaerobic” is probably inappropriate in obese patients with metabolic syndrome in view of the increase in serum nonesterified fatty acids and the lack of improvement in glucose metabolism [48–51, 53, 57, 59, 60].

Obese inpatients undergo daily functional rehabilitation exercises to optimize muscle strength and the lean to fat mass ratio, increase joint range of motion, and enhance cardiorespiratory conditioning. Since osteoarticular pain at spine, hip, and knee level is a major complaint and an obstacle to functional recovery in obese patients, physiotherapy focuses on joint unloading techniques, with the frequent use of taping and functional bandaging or sling therapy exercises [13–15, 17–20], passive and active lengthening and stretching of the muscular chains of the lower and upper limbs and the spine, strengthening and stabilizing of the lumbar trait, and active and passive mobilization of the dorsal spine [11, 12]. Manual lymphatic drainage and elastic compressive bandaging are also extensively used [13].

Resistance exercises aiming at muscle strengthening to reduce joint compression forces are performed 30–60 min daily. Their aim is also to improve balance by strengthening the heel stabilizer muscles [10]. Intensities of isotonic strengthening exercise are initially set at 40 % of the individual ten-repetition maximum during the first week, 50 % during the second week, and 60 % during the remaining rehabilitation period. The muscle groups to be trained are identified during the initial physiatrist evaluation. Strengthening-supervised exercises with arms and legs include dynamic standing and floor calisthenics using body weight as movement resistance. A major priority of exercise prescription is to focus on activities which contribute to muscular fitness and preserve muscle mass. This goal seems important also in view of the effects of caloric restriction, which result in reductions of both fat and fat-free mass. Water-based rehabilitation programs in a warm hydrotherapy pool are especially suitable for obese patients with osteoarthritis – since the buoyancy of water lightens body weight off the joints. This rehabilitation modality has been shown to be more effective than land-based programs in obese patients with chronic obstructive pulmonary disease [32].

Patients with severe motor limitations undergo physiotherapy and occupational therapy aimed at optimizing their capacities to cope with daily living activities through the use of walking aids, lifting, and transferring devices [9]. Respiratory rehabilitation is very often part of the rehabilitation program and includes adapting and training patients and caregivers to noninvasive ventilation [13]. Body awareness sessions which are carried out by trained therapists (using the Feldenkrais or the Courchinoux method), with a psychological supervision, typically represent an example of multidisciplinary treatment for obese patients with body scheme alteration and/or associated eating disorder.