Birth weight and grip strength in young Swedish males: a longitudinal matched sibling analysis and across all body mass index ranges

Abstract

Low birth weight is associated with a lower grip strength later in life. However, associations between birth weight among infants born at-term and factors driving associations between birth weight and grip strength are largely unknown. A cohort of 144,369 young men born at-term, including 10,791 individuals who had at least one male sibling/s, were followed until conscription where they performed a grip strength test. We used linear and non-linear regression analyses in the full cohort, and fixed-effects regression analyses in the sibling cohort, to address confounding by factors that are shared between siblings. After adjustment, each unit increase in birth weight z-score was associated with increases of 17.7 (95% CI, 17.2–18.2) and 13.4 (10.1–16.6) newton grip strength, which converts to approximately 1.8 and 1.4 kilogram-force in the full and within-families cohorts, respectively. The associations did not vary with young adulthood BMI. Birth weight, within the at-term range, is robustly positively associated with grip strength in young adulthood among men across all BMI categories and associations appears to be mainly driven by factors that are not shared between siblings. These findings underline the importance of recognizing the influence of low birth weight, also within the at-term-range, on young adulthood muscle strength.

Pre‐ and post‐natal factors and physical activity in childhood: The Norwegian Mother, Father and Child Cohort study

“…Salonen et al 39 observed that the positive association between birth weight and LTPA observed in adults became non-significant after the inclusion of adult fat-free mass, 39 indicating that muscle mass may be a possible mediator. A low maternal pre-pregnancy BMI and a low birth weight may thus lead to lower physical activity due to lower muscle mass, 18,41,42 muscle strength, [43][44][45] muscle quality, 17 or cardiorespiratory fitness. 41,46,47 Skeletal muscle mass, BMI, physical fitness, and physical activity may mutually affect each other.…”

Elective and nonelective cesarean section and obesity among young adult male offspring: A Swedish population–based cohort study

“…During the study period, males could only be exempt from conscriptions (requiring state approval) if they suffered from chronic disease or severe handicap [35]. Except for in sensitivity analyses, we excluded those with extreme values of weight (≤40 or ≥150 kg), height (≤150 or ≥210 cm), and/or BMI (≤15 or ≥60 kg/m 2 ) at conscription ( n = 105) in accordance with previous studies [36]. All analyses were conducted as complete-case analyses because we a priori hypothesized any missing data to be missing completely at random and potentially missing not at random in a few cases; therefore, we excluded all individuals with missing height and/or weight at conscription ( n = 76,410) and/or those with missing information on other characteristics of interest (e.g., maternal BMI and maternal smoking) ( n = 55,826) (S1 Table).…”

“…Although our aim is to examine obesity, we quantify associations between CS and all categories of BMI as compared with normal weight BMI. Weight in kilograms and height in centimetres were measured at conscription using a standardized scale and a stadiometer [36] under supervision of a nurse or physician [38]. To facilitate comparisons with previous studies, we also examined the odds of obesity (BMI ≥ 30) using all other BMI categories as reference outcome (BMI < 30).…”

Low birth weight and its relation to physical fitness parameters in children: Its negative effect on muscle strength and cardiorespiratory endurance

“…There is evidence that individuals with extremely low (<1000 g), very low (<1500 g), and low (<2500 g) birth weights develop a physical fitness deficit during infancy until adulthood (Burns et al, 2009; Danks et al, 2013; Morrison et al, 2020; Rogers et al, 2005). Despite some inconsistency (Orterga et al, 2009; Salonen et al, 2011), poor physical fitness could be due to deficits in cardiorespiratory endurance and muscle strength (Ahlqvist et al, 2019; Clemm et al, 2012; Dodds et al, 2012; Ferreira et al, 2017; Inskip et al, 2007; Kensara et al, 2005; Moura‐dos‐Santos et al, 2013; Nobre et al, 2020). Therefore, this study aimed to evaluate whether birth weight acts as a prenatal determinant of physical fitness parameters and to determine the role of environmental or biological variables on this effect.…”