Growth of specific muscle strength between 6 and 18 years in contrasting socioeconomic conditions

Abstract

The influence of sex, age, and socioeconomic conditions on specific grip strength of 6-18-year-old individuals was studied among 1,704 males and 1,956 females belonging to the so-called "Cape Coloured" community in the western part of South Africa. Half of the participants of both sexes came from communities in the Greater Cape Town area where living conditions are comparable to those of middle-class First World communities (high SES). The other half came from the poorest rural communities of Klein Karoo (low SES). Arm circumferences, triceps skinfold thickness, and grip strength of the right and of the left hand were greater in individuals from high SES at all ages. Females within each SES group had skinfolds thicker than males, especially at older ages, and were weaker. Specific grip strength (SS), estimated as grip strength per unit area of cross section of the fat-free arm, increased with age in each group, was greater in males, and was significantly lower in low SES groups, than in the high SES ones, especially during and after puberty. It seems that SES difference in SS will persist into adulthood. Sexual differences in SS can be attributed to hormonal differences; while the SS increase with age and the difference between SES groups find no clear explanation in current theories of muscle growth and development. Since the speed of neuromuscular reaction observed in our participants is slower among low SES individuals, it seems that the difference in neuromuscular control of strength may be responsible for our findings. Differences in muscle metabolism and hormonal regulation must also be considered.

Social Inequalities in Grip Strength, Physical Function, and Falls Among Community Dwelling Older Men and Women

“…Using data from the 1946 National Survey of Health and Development (NSHD), Kuh found no differences in grip strength across social class groups; material deprivation and educational attainment were not analysed. Our results are also consistent with work by Rautio (Rautio et al, 2005), who showed that higher income was related to hand grip strength in a cohort of elderly people in Finland; Henneberg (Henneberg et al, 2001), who showed that grip strength between 6 and 18 years in a South African cohort was higher among those in better socioeconomic conditions; and the ERAS Study Group, who showed that socioeconomic deprivation was associated with a worse clinical course of rheumatoid arthritis (including worsening grip strength; ERAS Study Group, 2000).…”

Socioeconomic Influence on Caries Susceptibility in Juvenile Individuals with Limited Dental Care: Example from an Early Middle Age Population (Great Moravia, 9th-10th Centuries A.D., Czech Republic)

“…(Espeland et al, 1988;Rudney et al, 1983;Watt et al, 1997;Williams & Curzon, 1985). Nevertheless, our results counteract several other studies (on past and present populations), which claim that the socioeconomic status influence the health (Goodman et al, 1988;Hauser, 1994;Henneberg et al, 2001;Kim & Durden, 2007). Although a direct parallel is difficult, this is a striking result.…”

Adiposity is associated with improved neuromuscular reaction time

“…This is because it determines, to a certain extent, the quality and quantity of nutrients available, it regulates energy At a more specific level the quality of nutrition may regulate NMRT by providing the necessary building blocks for the nervous system, irrespective of myelination and through physiological effects of food composition that may influence brain physiology. Additionally, patterns of physical activities, both daily activities and special exercise regimes provides training of certain reflexes and may influence muscle composition in terms of fast and slow twitch fibres [37]. Body height and body proportions may also influence NMRT as they determine the length of peripheral nerves and architecture of the musculoskeletal system.…”