Hand grip strength in 12 years old Children in Serbia – changes over 50 years

Сажетак : Недавна истраживања указују на евидентни тренд смањивања нивоа физичких активности код деце. Резултати овог истраживања указују да ниво јачине стиска шаке код деце не прати раст у телесној маси. Пре скоро пола века телесна маса код дванаестогодишњака је била за око 40% мања него код њихових вршњака у 21. веку. Телесна маса је порасла са 36.26 kg на 50.92kg. Oво повећање од приближно 15кг је значајно веће него повећање у нивоу мишићне јачине мерене стиском шаке, а изражено такође у килограмима. То доводи до озбиљне бриге не само тренда јачине мишића, већ и целокупног здравственог стања деце. Неопходна је промена целокупног окружења и начина живота деце, заједно са стварањем прилика и повољне мотивационе климе за рекреативно бављење спортом и различитим видовима физичке активности.

Кључне речи : Jачина стиска шаке, промене, деца

1.    INTRODUCTION1

Majority public health recommendations indicate that children and adolescents should accumulate at least 60 min of moderate to vigorous physical activity (MVPA) each day (WHO, 2010). Most frequent chronic diseases today could be prevented or postponed by adoption of healthy habits in childhood. If established in childhood and adolescence they could be carried into adulthood.

Important aspect of physical fitness and health status is muscular strength. In an extensive prospective study of male adolescents low levels of muscular strength were recognized as an important risk factor for major causes of death including cardiovascular disease in an extensive prospective study of male adolescents aged 16-19 (Orte- ga et al., 2012). Additionally, decrease of muscle strength may cause significant functional limitations (Morey, 1998; Takken, 2003).

Unfortunately, recent epidemiological research (Tudor-Locke, 2010; Runhaar J, et al., 2010) indicate that contemporary youth are not as active as they should be and reductions in physical activity start in early preadolescence. If we compared present day physical capabilities with the ones 10 years ago, we would come to a similar conclusion. There are several studies investigating different population, but coming to the same conclusion. There is an evident trend of decrease in children and adolescents muscular capabilities observed in English, Dutch and Spanish primary school children and adolescents (Cohen, 2011; Moliner-Ur-diales 2010, Nyberg, 2009). Without interventions that target deficits in muscular fitness and motor skill performance early in childhood, these contemporary trends are likely to continue and the gap between youth with low and high levels of muscular fitness and motor skill competence will continue to increase parallel with their growth.

A. Ignjatović, G. Budimir Ninković, N. Stevanović

Hand grip strength test among all muscle function tests is a simple, non-invasive marker of muscle strength of upper extremities, suitable for use in school, sport clubs, and medical facilities. Since reduced muscle strength is associated with loss of physical capabilities, loss of bone mineral density in adults (Kaya, 2005) and youth (Chan, 2008), outcome in acute and chronic disease and negative impact on recovery after illness or surgery (Humphreys, 2002; Kl-idjian, 1998; Webb, 1989) and nutritional status (Norman et al., 2010), special attention should be on the results of this muscle function test in all ages, especially in children.

2.    METHODOLOGY 2.1.    Subjects

The sample was composed of twelve years old participants in several nationwide population-based investigations: the Study of Polic et al. (1962); the EUROFIT difference in Belgrade children 2009-2014. And several PhD thesis with conducted between this large samples. Form longitudinal PhD studies initial measurement ware taken. Oldest study included in this investigation was the study by (Kurelic et al) conducted in 1962/63 with children aged 7-19. Total sample in this research was 65179 children from 239 schools. From this sample 911 children from Republic of Serbia performed hand grip strength test. From Dragic PhD thesis three groups conducted hand grip test (n 1 =20, n₂ = 34, n₃=38). In Eurofit test 51 student aged 12 performed hand grip test in 2014.

2.2.    Procedure

The hand grip strength test is considered as an objective index of general upper body strength and overall muscle strength. During handgrip strength test subject should perform forceful flexion of all finger joints with the maximum voluntary force that they are able to exert under normal conditions. The synergistic action of flexor and extensor muscles and the interplay of muscle groups is

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an important factor in the strength of the resulting grip. Many subjects were included in this investigation so the results might be influenced by the strength of the grip, hand dominance, fatigue, time of day, age, nutritional status, restricted motion, and other conditions.

2.3.    Statistical analysis

The data are presented as mean ± SD unless otherwise stated. Mean differences of the secular trends in handgrip strength between measurement points were analyzed. We calculated the effect size statistics as Cohen’s d (standardized mean differences) and 95% confidence interval. Values of Cohen’s d ~0.2, ~0.5 and ~0.8 are considered small, medium and large effects, respectively (Nakagawa, 2007).

3.    RESULTS

The characteristics of the study population by measurement point (1962–2014) are shown in Table I. Subject had lower levels of handgrip strength than their counterparts 50 years later (Cohen’s d ~0.29). Table 1 shows the mean of handgrip strength tests by 12 years old children in all measurement points. Children in 2014 had significantly higher weight and height compared to those measured in 1962.

Hand grip strength and body weight in children age 12 over the last 50 years

Graph 1: Hand-grip strength and body weight changes in twelwe years old children in Serbia from 1962.

Source: Result of the author’s research work.

4.    DISCUSION

The result of this investigation showed slight increase in muscle strength in hand grip of children in Serbia. Youth in 1962 had slightly lower levels of muscle hand grip strength then their counterparts several decades after. However, average weight showed more significant increase over the same period. Weight of 12 years old youth increased from average of 36.26kg to 50.92kg. The increase of ≈ 15kg, make the increase of more than 40% for this time period. The incsease in weight fail to follow the increase in muscle strength which should reise serious concerns toward children trend of development.

Available reports all around the world show different trends depending on geographical region. There are few studies providing data for grip strength in large groups of children

• A. Ignjatović, G. Budimir Ninković, N. Stevanović

  from the USA (Ager et al., 1984; Mathiowetz et al., 1986) and Australia (Newman et al., 1984; Fullwood, 1986). These studies from 1980s show higher grip strength values than even earlier study in 1960s (Burmeister, 1974). Results of the grip strength tests in American children in 1964 were advanced by 1.5–2 y compared with data collected as early as 1899 (Monpetit, 1967). Grip strength in children in the USA showed trend of constant increase form start of the XIX century toward the late years of the same century.

Normaive data for hand grip (Hagen Ross, 2002) for twelve years old children show similar values of hand grip strength as observed in studies from our investigation. Hagen Ross reported 22.4kg (219.9N ± 38) as normative hand strength for 12 yeast old boys ( n = 267) and 18.07 kg for girls (177.3N ± 46.3). However, average weight of this sample is 44kg. These normative data from Sweden (Hagen Ross, 2002) are in line with the results from studies conducted a decade earlier in Serbia (Dragic, 1993). The continued increase in weight all over the world demands for constant update in hand-grip strength normatives.

Bearing in mind the presented results we can consider the educational implications of the trend of weakening strength of fists in children and an increase in body mass. We are especially interested in what can be done pedagogically, especially in the context of free time and how we can contribute to the development of values and habits of children that would protect and improve their physical health. It should be borne in mind that children today spend their free time dominantly with the ICT, while physical activity outside the closed area is almost completely suppressed. Many authors identify modern generations as digital natives (Prensky, 2001), or net-generation (Tapscott, 2008) who are more focused on mind managing of information and digital content than on physical and motor activities, especially those that require greater physical strength. Without intending to disparage educational importance of information and communication technologies, we want to point out that a large number of hours that children spend physically passive at school and home should have negative consequences for somatic health of children. Weakening of physical and health capacities of children jeopardizes their potential for development, and this has negative implications on education because whole aspects of personality development are neglected.

Free time, therefore appears as a space for pedagogical influence, that would allow to find a balance between the physical passive learning and entertainment that today dominate over physical active recreation that should be present more. In order to achieve this it is necessary to realize several requirements.

The first requirement refers to the pedagogical training of parents in providing assistance and support to children in physical activities. Counseling for parents, free courses, tutorials and proper literature can help parents to raise awareness about the importance of physical activity and so to provide adequate support to children.

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The second requirement involves systematic and regulatory solutions in the education system which would ensure that children are physically active at school, even when they do not have classes. This can be achieved by equipping schools sports equipment and dedicated courts, as well as creating conditions for sports sections and recreational sports.

The third requirement refers to the role of the public in the promotion of physical activity in free time. A clear and strong support of the state, local communities, public institutions and especially the media could significantly improve the situation in terms of the motivation of young people to engage in physical activities. Currently, it appears that the public is not sufficiently engaged in promoting physical activity and healthy lifestyles, and that they are no longer popular among children. Changes in media content and opportunities for recreational and sporting events could motivate kids to get more involved in sports and physical recreation.

The realization of these three requirement may create conditions that teachers and parents provide better physical and health education, and thus act preventively to prevent outbreaks of disease caused by passive lifestyle among children.

5.    CONCLUSION

Decreas of muscle strength may cause significant functional limitations and health problems. The increase of body mass of more than 40% 50 years time period in our sample ofs 12years old children wasn’t followed by the increase in muscle strength. This reise serious concerns toward children trend of muscle strength development and overall health and physical capabilities.