Harmonious physical development is a critical indicator of a child’s health [1, 2]. Unfortunately, over 25% of school-age children and adolescents cannot boast physical fitness [3–5], and the proportion of obese and overweight children is alarmingly high [1, 3, 6–9]. This situation is largely attributed to a contemporary lifestyle and diet that would ideally promote normal growth and development, protect against diseases and help children to adapt to the environment [10, 11].
Unbalanced diet and unhealthy eating habits in the critical periods of child development delay growth and may promote disease [12–14]. In recent years, the incidence of obesity in the Samara region has been stably high, reaching 54.1 cases per 10,000 children in 2016. These figures are well above the average rate of 36.7 reported in the Russian Federation [15].
This dictates the need for instilling healthy lifestyle and eating habits in children. Summer may be a good time for taking measures, as many children spend their holidays in summer camps. The camps are expected to provide a wide range of activities, as well as improve a child’s health. Nutrition is a crucial factor that affects the overall health, growth and development, contributing to the efficacy of health programs [16].

Advances in modern science have been instrumental in elaborating the efficacy criteria for summer camp healthcare. The guidelines on the Methods for the assessment of the efficacy of health initiatives in health resorts for children (2.4.4.0127- 18; adopted instead of 2.4.4.0011-10), recommend using a grading scale for measuring the dynamics of height, body weight, muscular strength, and respiratory function in children during a summer camp session [17]. The expert panel of the Ministry of Healthcare of the Russian Federation on the hygiene in children and adolescents has approved a protocol ROSHUMZ-15-2014 on the Comprehensive assessment of the efficacy of health initiatives in health resorts for children (Protocol No. 4 dated May 6, 2014). The protocol proposes a method for assessing the efficacy of health programs for children based on the dynamics of height, weight, cardiovascular and respiratory function, physical fitness, and morbidity rates during a camp session. Some researchers also recommend using a cardiac exercise test [18] and tests of physical [19] and mental activity [20].

We believe that such protocols should also focus on the assessment of a child’s nutritional status and the analysis of its dynamics during a summer camp session. This can help to reduce the incidence of nutrition-related diseases [21].
The methods proposed earlier are intended to analyze changes to anthropometric parameters in children with a variety of physical statuses. Recently, other approaches have been introduced, involving the use of diagnostic equipment for the assessment of a child’s nutritional status [21, 22], including bioelectrical impedance analysis (BIA). However, the feasibility of BIA for such tasks still needs to be investigated.
The objective of this study was to provide a rationale for the use of bioimpedance analysis and anthropometric measurements as efficacy criteria for summer camp healthcare.

METHODS

The study was conducted in 346 children and teenagers (125 boys and 221 girls) aged 8 to 15 years from 3 summer camps located in the Samara region. The camps were selected from those recreational organizations whose directors agreed to cooperate. More than one camp was included in the study to ensure the probability of encountering different patterns of changes to the anthropometric and bioimpedance parameters. Each camp had playgrounds, sports facilities and dining halls. Specialized sports camps were not included in the study. The daily schedules were standard. The study enrolled the residents of the Samara region whose medical histories placed them into health groups I or II. Children who had chronic conditions or pronounced peripheral edemas, were undergoing medication therapy at the time of the study, permanently resided outside of the Samara region, or whose parents refused to give their consent to participate were excluded.

Measurements were performed twice: on the first and second days upon arrival to the camp, and two days before leaving for home. A camp session lasted 21 days. Anthropometric measurements were taken following a standard unified method [23]: height was measured using an anthropometer (Kafa; Russia) with a 0.5 cm precision; body weight was measured on the electronic medical scales EMS-150-Massa-K (Massa-K; Russia) with a 60 g precision. The children’s physical development was assessed using a modified regression scale for the Samara region [24]. Body composition was estimated on the АВС-01 analyzer (Medass; Russia) operated at 50 kHz frequency. A standard tetrapolar method was applied; it is based on 4 electrodes placed over the hand and ankle of a child lying in the supine position. During the procedure, the angle between the right shoulder and the vertical body axis was 45°; the right forearm was parallel to the vertical body axis; the feet were positioned shoulder width apart. Bioimpedance measurements were taken in the morning before meal or 2.5–3 hours after meal. No vigorous physical activity or physiotherapy preceded the procedure. The following parameters were estimated: total fat mass (FM), skeletal muscle mass (SMM), and the basal metabolic rate (BMR) [25, 26]. The obtained data were saved in Microsoft Excel 2010 (Microsoft; USA) and later processed in Statistica ver. 13.1 (StatSoft Inc.; USA). Body weight dynamics during a camp session were analyzed using the Wilcoxon test for paired samples. Changes in the total proportion of children with normal physical development (NPD), body weight deficit (BWD) and excess body weight (EBW) were analyzed using McNemar's chi-squared test. Between the camps, the dynamics were compared using Pearson’s chi-squared test. Differences (M ± m, where M is an arithmetic mean, m is an arithmetic mean error) were considered significant at p < 0,05.

RESULTS

Changes in the physical development during a camp session were analyzed and compared between children from 3 different camps. Data on camp 1 are shown in tab. 1.
In camp 1, 62 children with NPD (47.7%), 19 children with BWD (14.6%) and 31 children with EBW (23.8%) retained their physical status. A positive trend was observed in 8 children with BWD (6.2%) and 5 children with EBW (3.8%), whose physical development could be described as normal by the end of the session. Negative dynamics were observed in 4 children (3.1%): although their physical health was normal when they arrived at the camp, they lost weight and developed BWD during their stay. One more child (0.8%) was physically fit upon arrival, but later gained weight and thus joined the EBW group. The general trend in weight change was nevertheless insignificant (p = 0.415).
The analysis of changes in the proportion of children with NPD, BWD and EBW in camp 1 did not reveal any significant differences inside those groups (tab. 2).
In camp 2, 56 children with NPD (48.7%), 16 children with BWD (13.9%) and 31 children with EBW (27%) retained their health status (tab. 3).
A positive change was observed in 5 children with BWD (4.3%) and 2 children with EBW (1.7%), whose physical development was characterized as normal at the end of their stay at the camp. Three children (2.6%) had developed BWD and 2 children (1.7%) had gained weight, thus moving to the EBW group by the end of the camp session (tab. 4). Similarly to camp 1, the overall body weight dynamics were insignificant (p = 0.585).
Weight trends in each separate health group (NPD, BWD, EBW) were also insignificant (tab. 4).
In camp 3, 62 children with NPD (61.4%), 13 children with BWD (12.9%) and 6 children with EBW (5.9%) retained their health status. Positive changes were observed in 6 children with BWD (5.9%) and 5 children with EBW (5.0%), who had moved into the NPD group. Negative dynamics were observed in 9 children who had developed body mass deficit by the end of their stay. In camp 3, the overall weight dynamics were reliable (p = 0.025) (tab. 5).

There were more children in camp 3 who had lost weight during their stay than those who had gained it (p = 0.025). Of 14 children (12.2%) who had lost weight, 9 had BWD at the end of the camp session and 5 had moved into the NPD group. Six children with initial BWD had gained weight and moved into the NPD group by the end of their stay. Importantly, weight loss during a camp session can be regarded as a positive health effect only for initially overweight children. For children with NPD and BWD such changes are not beneficial.
We analyzed the dynamics of body weight in children with different physical statuses during their stay at a summer camp (tab. 6). For children who were initially fit or overweight, the changes were statistically insignificant. For example, in camp 1 the children with NPD weighed 47.05 ± 1.1 kg upon arrival and 47.34 ± 1.12 kg (p = 0.347) before leaving for home. At the same time, the children with weight deficit demonstrated a significant increase in their body weight by the end of a camp session. In camp 2, such children weighed 39.78 ± 1.48 kg upon arrival and 41.37 ± 1.66 kg (p = 0.002) at the end of the camp session.
Bioimpedance analysis is expected to confirm such positive body weight dynamics. During their stay at camp, children are supposed to receive a balanced diet and enough physical exercise, which will be reflected in their bioimpedance results. Fat mass will decrease, whereas skeletal muscle mass and the basal metabolism rate will grow. In camps 1 and 2, the average values of those bioimpedance parameters increased slightly, suggesting that the children had been receiving a balanced diet and sufficient physical exercise throughout their stay, but those changes were statistically insignificant. In camp 3, both fat and skeletal muscle masses decreased significantly. This may have been due to the inadequate diet, insufficient physical activity or a poorly structured daily schedule. Insignificant changes in the metabolism rate confirm our hypothesis (tab. 7).
FM, SMM and BMR were measured in each child. Based on the measurement results, 7 groups were distinguished (tab. 8). Groups 1 and 3 consist of the children who received enough exercise and healthy diet. In group 2, the children were physically active, but food intake did not compensate for energy expenditures. In group 4, the children were also quite active, but their diet was too rich in calories. The children from groups 5, 6 and 7 lacked physical activity and consumed too many calories (tab. 8).

The largest proportion of children who demonstrated positive changes in their body composition (groups 1–3) was observed in camps 1 and 2 (44.61% and 44.34%, respectively). At the same time, the number of children whose fat mass had increased while their skeletal mass had not was also quite high in camps 1 and 2. In camp 3, 19.8% of children had gained FM by the end of their stay but lost SMM or retained it at the initial level. Body weight dynamics in camp 3 inferred from the anthropometric measurements are confirmed by the presence of a significant proportion of children constituting groups 1–3.

DISCUSSION

The anthropometric measurements identified children with negative body weight dynamics observed during their stay at a summer camp: the initially fit children had developed body weight deficit or gained weight by the end of the camp session. This is an alarming trend, especially because it was observed in all three studied camps. In camp 3, body weight dynamics were statistically significant and were not always positive. Some physically fit children and their weight-deficient peers gained weight, which can be regarded as a positive effect, but there was also a big proportion of children who lost weight during their stay. BIA confirms the results of the conducted anthropometric measurements. Based on the dynamics of fat mass, skeletal muscle mass and basal metabolism rates measured in each child, we can assess the quality of nutrition at camps and its impact of children’s health. Weight gain that serves as a criterium of healthy physical development and therefore suggests a positive effect of a health program can also result from an increase in fat content [17, 20, 25]. If children receive a balanced diet and are provided with physical activities that match food intake, changes in the body composition will not be manifested as an increase in fat mass. Skeletal muscle mass can grow or remain stable throughout a camp session [18, 19, 25]. In our study, weight gain was accompanied by a healthy increase in skeletal muscle mass, as well as by an unhealthy increase in fat mass in many children. At the same time, weight loss during the camp session was not always associated with a drop in fat mass, but in some cases was indicative of skeletal muscle mass loss, indicating the absence of a positive effect on children’s health. Anthropometric measurements and BIA conducted in camp 1 suggest that the children were provided with a balanced diet and energy intake matched energy expenditures. In camp 2, the diet was probably too rich in calories and energy intake exceeded energy expenditures. In camp 3, food intake could not compensate for energy expenditures.

CONCLUSIONS

During a summer camp session, a child’s anthropometric parameters and body composition undergo certain changes that can reflect his/her nutritional status. The dynamics of the anthropometric parameters and bioelectrical impedance analysis can provide information about the diet a child receives and the physical activity he/her is provided with. Therefore, anthropometric measurements and BIA can be used as efficacy criteria for summer camp healthcare.