Subjects
One hundred thirty-nine adolescents (56 boys and 83 girls, age range: 13–17 y) and 71 adults (27 males and 44 females, age range: 35-68 y) with obesity, participated in this study. Among adolescents, BMIs for gender and chronological age were above the 99th percentile [32], while for adults the BMIs were above 35 kg/m2. Subjects were recruited as inpatients from the Division of Auxology (subjects aged < 18 y) and from the Division of Metabolic Diseases (subjects aged > 18 y), Istituto Auxologico Italiano, IRCCS, Piancavallo (VB) Italy. Before admission to the hospital for BWRP, none of the subjects had engaged in structured physical activity (i.e., regular activity of more than 60 min/week). All subjects had a complete medical history and physical examination. None of the adolescents or adults with obesity had signs or symptoms indicative of serious cardiovascular, respiratory, or orthopaedic disease that could significantly interfere with the functional test used in the study.
Study Protocol
The study was approved by the Ethical Committee of the Istituto Auxologico Italiano (Milan, Italy, research code: 01C124, acronym: PRORIPONATFIS) and was in accordance with the Declaration of Helsinki 1975, as revised in 2008. For adolescents, the protocol was explained to parents and written informed consent was obtained from parents or legal representatives. Patients aged ≥18 gave written informed consent to participate in the study. Patients were hospitalized for a period of 3 weeks in the Division of Auxology (patients < 18 y) or in the Division of Metabolic Diseases (patients > 18 y), Istituto Auxologico Italiano, IRCCS, Piancavallo (VB). They followed a 3-week personalized BWRP consisting of lifestyle and physical activity, nutrition education, and psychological counselling. Full testing sessions were conducted at the beginning (T0) and at completion of the 3-week BWRP (T21). Testing session included assessment of anthropometric characteristics, body composition, blood pressure (BP), lower limb muscle power, lower limb functionality, and ability to perform ADL (see below for detailed description).
Physical Activity
The physical activity program consisted of 5 training days per week, under the supervision of a physical trainer. Each training session included: (i) 45–60 min per day of aerobic activities (walking on a treadmill or cycling on an ergometer) under heart rate monitoring (HR) and medical supervision (ii) 5–7 min of stretching before and after training. The intensity of aerobic activities was set at heart rate (HR) corresponding to 60 and 80% of the individual maximal HR estimated as 220-age (year). The research assistant and the physical trainers verified that each subject participated in each training session, performed the exercises correctly, and completed at least 95% of the exercise session and program.In addition, subjects had 1 h/day of aerobic leisure activities at the institution on Saturday and Sunday.
Diet and Nutritional Education
A Mediterranean diet was prescribed based on the initial basal metabolic rate test and physical activity level for each patients, and the amount of energy to be given with diet was calculated by subtracting approximately ~25% from the estimated daily energy expenditure. In terms of macronutrients, the diet contained 21% proteins, 53% carbohydrates, and 26% lipids. The diet composition was formulated according to the Italian recommended daily allowance [33]. Each patient was free to choose foods from a heterogeneous daily menu, although five daily servings of fruits and vegetables were mandatory. Foods to which the patient reported allergic reactions were eliminated from the menu. A fluid intake of at least 1.5 l/day was encouraged. In addition, the dietitian team checked that each subject had eaten every meal. On each day of the BWRP, the patients had dietetics classes consisting of lectures, demonstrations, and group discussions with and without a supervisor.
Psychological counselling
Cognitive-behavioural therapy strategies, such as stimulus control procedures, problem-solving and stress management training, development of healthy eating habits, assertiveness and social skills training, cognitive restructuring of negative maladaptive thoughts, and relapse prevention training, were chosen for the psychological sessions, which were conducted by a clinical psychologist 2-3 times per week in individual or group sessions. When possible (1 day per week), additional sessions were also conducted with patients' parents aimed at improving motivation for lifestyle change and interpersonal communication.
Measurements
Physical characteristics and body composition
Medical history was obtained and a baseline physical examination was performed. Stature and body mass (BM) were measured using a Harpenden stadiometer (Holtain Ltd., UK), and an electronic scale (Selus, Italy), respectively, with the subject wearing only light underwear. BMI (kg/m2) was calculated. The standard deviation score (SDS) of BMI-SDS was calculated using the LMS method [32] on Italian reference values for children and adolescents [34]. Body composition was measured using a multifrequency tetrapolar impedancemeter (BIA, Human-IM Scan, DS-Medigroup, Milan, Italy) with a delivered current of 800 μA at a frequency of 50 kHz. To reduce measurement errors, care was taken to standardise the variables that affect the validity, reproducibility and precision of the measurement. Measurements were performed according to the method of Lukaski et al. ([35] (after 20 min of rest in the supine position with arms and legs relaxed and without contact with other parts of the body) and under strictly controlled conditions according to NIH guidelines [36] All females were studied outside of the menstrual period in order to avoid any possible influence on fluid retention, as suggested by the NIH guidelines [36]. For adolescents, Fat-Free Mass (FFM) was calculated using the prediction equation developed by our group [37], whereas for adults, the equation developed by Gray et al. [38] was used. FM (kg) was derived as the difference between BM (kg) and FFM (kg). As well, two blood pressure measurements (BP) were taken after participants had been sitting for at least 5 min, and the mean was used for statistical analysis.
Lower Limb Muscle Power
The Stairs Climbing Test (SCT) is a well-standardized procedure for measuring maximal anaerobic power in adolescents and adults with obesity [30,39]. Prior to administering the test, 2–3 practise trials were scheduled to allow subjects to gain sufficient confidence with the technique. Briefly, subjects were asked to climb an ordinary stair at the highest possible speed, according to their abilities. The stairs consisted of 13 steps of 15.3 cm each, so that a total vertical distance of 1.99 m was covered. An experimenter measured the time taken to complete the test using a digital stopwatch. SCT repeatability in obese subjects has been previously evaluated in our laboratory and the coefficient of variation between measurements was found to be lower than 5% [30].
Short Physical Performance Battery
A Short Physical Performance Battery (SPPB) [40,41] was administered. The SPPB consists of the following 3 parts: i. Tests of standing balance, included semi-tandem position, side-by-side stands and tandem position (each held for 10 seconds), ii. Walking a 4 m distance at normal gait speed, and iii. Rising from a chair and returning to the seated position 5 times. Scores for each item ranged from 0 to 4, for a maximum of 12 points. Performance categories were created for each set of performance measures to allow for analyses that included those unable to perform a task. The three tests of standing balance were considered hierarchical in difficulty by assigning a single score from 0 to 4 for standing balance [40] For 4 m walking and repeated chair stands, a score of 0 was assigned to those who could not complete the task. Those who were able to complete the task were assigned scores from 1 up to 4, corresponding to quartiles of time required for the task, with the fastest times scored as 4 [40]. Higher scores were associated with better lower limb functionality [41].
Physical Performance Test
The ability to perform ADL was assessed using the Physical Performance Test (PPT) [43]. The PPT test used in the present study includes 7 standardized tasks (i. Walk 15.2 m, ii. Put on and take off a coat, iii. Pick up a coin, iv. Lift a book, v. Simulate the act of eating, vi. Perform a 360° turn, and vii. Write a sentence). The score for each item ranged from 0 to 4, with 0 corresponding to "unable to do" and 4 corresponding to "most able or quickest" [43]. The maximum score was 28, and participants were classified as mildly to moderately frail if they scored between 19 and 24 [44].
Statistical Analyses
Statistical analyses were performed using Graph Pad Prism version 9.1.0-2021 software (GraphPad Software, Inc. - San Diego, CA, USA) with a significance set at P < 0.05. All results were expressed as mean and standard deviation (SD). Normal distribution of the data was tested using the Kolmogorov-Smirnov test. The effects of gender, time, and the interaction between these variables on physical characteristics, body composition, lower limb muscle power, lower limb functionality and ability to perform ADL were tested using General Linear Model repeated measures. When significant differences were found, a Bonferroni post hoc test was evaluated implementing multiple comparisons. Relationships between the different factors were examined using Pearson or Spearman product–moment correlation coefficient.