Factors associated with handgrip strength across the life course: A systematic review

BACKGROUND

Muscle strength is essential for healthy ageing. Handgrip strength (HGS) has been recommended by expert bodies as the preferred measure of muscle strength, in addition to being considered a strong predictor of overall health. Cross-sectional studies have shown several potential factors associated with HGS, but a systematic review of factors predicting HGS over time has not previously been conducted. The aim of this study is to systematically review the literature on the factors associated with adult HGS [at follow-up(s) or its rate of change] across the life course.

METHODS

Searches were performed in MEDLINE via Ebsco, Embase and SPORTDiscus databases. Longitudinal studies assessing potential factors impacting adult HGS over time were included in the analyses. Based on previously established definitions of consistency of results, a semiquantitative analysis was conducted using the proportions of studies supporting correlations with HGS.

RESULTS

A total of 117 articles were included in this review. Factors associated with HGS were grouped into 11 domains: demographic, socioeconomic, genetic, early life, body composition, health markers/biomarkers, health conditions, psychosocial, lifestyle, reproductive and environmental determinants. Overall, 103 factors were identified, of which 10 showed consistent associations with HGS over time (i.e., in at least four studies with ≥60% agreement in the direction of association). Factors associated with greater declines in HGS included increasing age, male sex, higher levels of inflammatory markers and the presence of cardiovascular diseases. Education level, medication use, and self-rated health were not associated with the rate of change in HGS. Increased birth weight was associated with a stronger HGS over time, whereas depressive symptoms were linked to a weaker HGS, and smoking habits showed null associations.

CONCLUSIONS

Comparison between studies and estimation of effect sizes were limited due to the heterogeneity in methods. Although sex and age may be the main drivers of HGS decline, it is crucial to prioritize modifiable factors such as inflammation and cardiovascular diseases in health interventions to prevent greater losses. Interventions to improve birth weight and mental health are also likely to produce positive effects on muscle strength. Our results point to the complexity of processes involving muscle strength and suggest that the need to better understand the determinants of HGS remains.

Omega-3 polyunsatured fatty acids and physical performance across the lifespan: a narrative review

Background and Aims

Physical performance is a major contributor of mobility and independence during older life. Despite a progressive decline in musculoskeletal function starts from middle age, several factors acting during the life-course can negatively influence musculoskeletal functional capacities. Lifestyle interventions incorporating nutrition and physical exercise can help maximizing the muscle functional capacities in early life as well as preserving them later in life. Among various dietary compounds, omega-3 polyunsaturated fatty acids (PUFAs) are gaining growing attention for their potential effects on muscle membrane composition and muscle function. Indeed, several pathways are enhanced, such as an attenuation of pro-inflammatory oxidative stress, mitochondrial function, activation of the mammalian target of rapamycin (mTOR) signaling and reduction of insulin resistance.

Methods

We performed a narrative review to explore the existing literature on the relationship between omega-3 PUFAs and physical performance across the life-course.

Results

Growing evidence from randomized controlled trials (RCTs) suggests beneficial effects of omega-3 PUFAs on muscle function, including physical performance parameters in mid to later life. On the other hand, despite a direct association in early life is not available in literature, some mechanisms by which omega-3 PUFAs may contribute to improved adult physical performance could be hypothesized.

Conclusion

Omega-3 PUFAs are gaining growing attention for their positive effect on muscle function parameters. The integration of physical function measures in future studies would be of great interest to explore whether omega-3 PUFAs could contribute to improved muscle function, starting from early life and extending throughout the lifespan. However, larger and high-quality RCTs are needed to fully elucidate the beneficial effects of omega-3 PUFAs supplementation on muscle mass and function.

Determinants of handgrip strength at age 2 years in children born moderate and late preterm and associations with neurodevelopmental outcomes

BACKGROUND

Handgrip strength (HGS) indicates current and future health. Although preterm infants have an increased risk of poor grip strength in later life, its determinants and relationship with neurodevelopment are not well understood.

AIMS

To determine HGS in children born preterm and explore the relationship of HGS with demography, anthropometry, nutritional factors, and neurodevelopmental outcomes.

STUDY DESIGN

A prospective cohort study of moderate-late preterm babies enrolled in a randomised trial of nutritional support strategies, the DIAMOND trial.

SUBJECTS

A total of 116 children born between 32 and 35 weeks' gestation, whose HGS was measured at 2 years' corrected age.

OUTCOME MEASURES

HGS was measured using a dynamometer, and neurodevelopment was assessed using the Bayley Scales of Infant Development-III. Anthropometry and body composition were assessed at birth, discharge, and at 4 months' and 2 years' corrected age. Information on demographics and breastfeeding practices, including type of milk at discharge and duration of exclusive breastfeeding, was collected using questionnaires.

RESULTS

The mean (standard deviation) HGS was 2.26 (1.07) kg. The Bayley scores were < 85 (-1 standard deviation) in 6 %, 20 %, and 1 % for the cognitive, language, and motor scales, respectively. Multiple regression analysis revealed that HGS was positively associated with language and motor scores (p < .05) after adjusting for confounding factors. HGS was not associated with sex, anthropometry, body composition, or breastfeeding practices. Maternal education was independently associated with HGS (p < .01).

CONCLUSIONS

HGS at age 2 years in children born moderate-late preterm is associated with language and motor development and maternal education level.

Cultural beliefs, attitudes and perceptions of lactating mothers on exclusive breastfeeding in The Gambia: an ethnographic study

BACKGROUND

WHO/UNICEF recommends that women in resource-poor developing countries- like the Gambia, should exclusively breastfeed their infants for the first six months of their lives because of its health benefits to both mother and infant. The study aimed to explore the cultural beliefs, attitudes, and perceptions of lactating mothers towards exclusive breastfeeding in The Gambia.

METHODS

This was a qualitative ethnographic study of culture-sharing groups of mothers with infants 4 to 6 months old. The study was conducted from July to October 2014 and data collection was done through a face-to-face, in-depth interview and moderate participant observation. The study recruited 22 breastfeeding mothers attending government health facilities in the Kanifing Municipality. The collected data were transcribed verbatim and analyzed through a constant comparison method generating six cultural themes, each with sub-themes.

RESULTS

Baby's welfare is traditionally based on the types of food mother's eat. To this end, mothers reportedly shunned eating green leafy vegetables, liquid and hot foods for their infants' wellbeing. Encounters such as weight loss, nipple inflammation, and backache, which mothers associated with hyper latching and sitting for prolonged breastfeeding, respectively, were among major undesirable physical effects revealed by the participants. Furthermore, the necessity of giving water to infants for their survival was illustrated as a barricade to exclusive breastfeeding practices. Likewise, the entrenched practice of giving charm water to instill the Islamic faith and shielding infants against evil spirits was another factor influencing exclusive breastfeeding practices. Finally, the belief that breast milk adequacy is based on breast size and nurturing men's physical strength by starting prelacteal feeds early in infancy also contributes to the meek exclusive breastfeeding rate among mothers.

CONCLUSION

This study could be a gazette piece for effective policy making and enhance nurses' cultural sensitivity while caring for lactating mothers. Cultural meanings of health care behaviors in lactating mothers challenge universally applying guidelines of exclusive breastfeeding to all societies. The study findings could benefit healthcare providers in informing policies and designing culturally adaptive and acceptable community-based breastfeeding intervention programs in resource-limited settings.

Musculoskeletal Changes Across the Lifespan: Nutrition and the Life-Course Approach to Prevention

Aging is characterized by the progressive decline of muscle mass and function, the so-called sarcopenia. Also bone loss is widespread among older people. Sarcopenia and osteopenia/osteoporosis are associated with several adverse outcomes including falls, risk of fractures, functional decline, frailty, and mortality. Recently, the life-course approach to prevent or delay functional decline has become very popular. Regarding musculoskeletal health, there is suggestive evidence that acting during critical or sensitive periods of life in which each person build-up its biological reserves may influence the rate of functional decline in the later stages of life. A life-course approach to musculoskeletal health should take place during early life when plasticity allows more easily the attainment of the peak of the musculoskeletal system driven by environmental stimuli. The rate of the subsequent decline will depend on the peak previously reached. Nutrition and physical exercise are important environmental factors that can influence musculoskeletal development by favoring and maintaining peak bone and muscle mass and strength. Here we provide an overview of body composition changes occurring across the lifespan and strategies based on nutrition and physical exercise to support musculoskeletal health as well as minimizing losses during older life.

The Hertfordshire Cohort Study: an overview

The Hertfordshire Cohort Study is a nationally unique study of men and women born in the English county of Hertfordshire in the early part of the 20 ^th century. Records that detail their health in infancy and childhood have been preserved, their sociodemographic, lifestyle, medical and biological attributes have been characterised in later life, and routinely collected data on their hospital use and mortality have been acquired. This paper provides an overview of the study since its inception in the 1980s, including its methods, findings, and plans for its future.

Epidemiology of Sarcopenia: Determinants Throughout the Lifecourse

Sarcopenia is an age-related syndrome characterised by progressive and generalised loss of skeletal muscle mass and strength; it is a major contributor to the risk of physical frailty, functional impairment in older people, poor health-related quality of life and premature death. Many different definitions have been used to describe sarcopenia and have resulted in varying estimates of prevalence of the condition. The most recent attempts of definitions have tried to integrate information on muscle mass, strength and physical function and provide a definition that is useful in both research and clinical settings. This review focuses on the epidemiology of the three distinct physiological components of sarcopenia, and highlights the similarities and differences between their patterns of variation with age, gender, geography and time and the individual risk factors that cluster selectively with muscle mass, strength and physical function. Methods used to measure muscle mass, strength and physical functioning and how differences in these approaches can contribute to the varying prevalence rates will also be described. The evidence for this review was gathered by undertaking a systematic search of the literature. The descriptive characteristics of muscle mass, strength and function described in this review point to the urgent need for a consensual definition of sarcopenia incorporating these parameters.

Epidemiology of sarcopenia and insight into possible therapeutic targets

Musculoskeletal ageing is a major public health concern owing to demographic shifts in the population. Sarcopenia, generally defined as the age-related loss of muscle mass and function, is associated with considerable risk of falls, loss of independence in older adults and hospitalization with poorer health outcomes. This condition is therefore associated with increased morbidity and health care costs. As with bone mass, muscle mass and strength increase during late adolescence and early adulthood, but begin to decline substantially from ∼50 years of age. Sarcopenia is characterized by many features, which include loss of muscle mass, altered muscle composition, infiltration with fat and fibrous tissue and alterations in innervation. A better understanding of these factors might help us to develop strategies that target these effects. To date, however, methodological challenges and controversies regarding how best to define the condition, in addition to uncertainty about what outcome measures to consider, have delayed research into possible therapeutic options. Most pharmacological agents investigated to date are hormonal, although new developments have seen the emergence of agents that target myostatin signalling to increase muscle mass. In this review we consider the current approaching for defining sarcopenia and discuss its epidemiology, pathogenesis, and potential therapeutic opportunities.

Sarcopenia and frailty: new challenges for clinical practice

Sarcopenia and frailty are important conditions that become increasingly prevalent with age. Sarcopenia is the loss of muscle mass and function, and frailty can be defined as multi-system impairment associated with increased vulnerability to stressors. There is overlap between the two conditions, especially in terms of the physical aspects of the frailty phenotype: low grip strength, gait speed and muscle mass. These measures have been associated with a wide range of ageing outcomes and can be assessed in the clinical setting. In terms of intervention, there is evidence for the benefit of resistance exercise programmes, although these may not always be feasible. Considerable research into the use of medicines, both existing and new, as well as dietary supplements is ongoing. Finally in order to prevent or delay the development of these conditions, an additional approach is to consider aetiological factors operating across the life course.

Sarcopenia and frailty: new challenges for clinical practice

Sarcopenia and frailty are important conditions that become increasingly prevalent with age. Sarcopenia is the loss of muscle mass and function, and frailty can be defined as multi-system impairment associated with increased vulnerability to stressors. There is overlap between the two conditions, especially in terms of the physical aspects of the frailty phenotype: low grip strength, gait speed and muscle mass. These measures have been associated with a wide range of ageing outcomes and can be assessed in the clinical setting. In terms of intervention, there is evidence for the benefit of resistance exercise programmes, although these may not always be feasible. Considerable research into the use of medicines, both existing and new, as well as dietary supplements is ongoing. Finally in order to prevent or delay the development of these conditions, an additional approach is to consider aetiological factors operating across the life course.

Birth weight, intrauterine growth restriction and nutritional status in childhood in relation to grip strength in adults: from the 1982 Pelotas (Brazil) birth cohort

Objective

The aim of this study was to evaluate the association among birth weight, intrauterine growth, and nutritional status in childhood with grip strength in young adults from the 1982 Pelotas (Brazil) birth cohort.

Methods

In 1982, the hospital live births of Pelotas were followed. In 2012, grip strength was evaluated using a hand dynamometer and the best of the six measurements was used. Birth weight was analyzed as z-score for gestational age according to Williams (1982) curve. Weight-for-age, weight-for-length/height, and length/height-for-age at 2 and 4 y were analyzed in z-scores according to 2006 World Health Organization Child Growth Standards. Lean mass at 30 y was included as possible mediator using the g-computation formula.

Results

In 2012, 3701 (68.1%) individuals were interviewed and 3470 were included in the present analyses. An increase of 1 z-score in birth weight was associated with an increase of 1.5 kg in grip strength in males (95% confidence interval, 1.1–1.9). Positive effect of birth weight on grip strength was found in females. Grip strength was greater in individuals who were born with appropriate size for gestational age and positively associated with weight- and length/height-for-age z-score at 2 and 4 y of age. A positive association between birth weight and grip strength was only partially mediated by adult lean mass (50% and 33% of total effect in males and females), whereas direct effect of weight at 2 y was found only in males.

Conclusions

It is suggested that good nutrition in prenatal and early postnatal life has a positive influence on adult muscle strength. The results from birth weight were suggestive of fetal programming on grip strength measurement.

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Newborns from southern Brazil were followed for 30 y.

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Birth weight and nutritional status in childhood were prospectively measured.

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Grip strength was positively related to birth weight and early nutritional status.

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Coefficients of the association between birth weight and grip strength were higher in males.

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Birth weight was associated with adult grip strength independent of current lean mass.

Sarcopenia: burden and challenges for public health

Sarcopenia, operationally defined as the loss of muscle mass and muscle function, is a major health condition associated with ageing, and contributes to many components of public health at both the patient and the societal levels. Currently, no consensual definition of sarcopenia exists and therefore it is still a challenge to establish the actual prevalence of sarcopenia or to establish the direct and indirect impacts of sarcopenia on public health. Anyway, this geriatric syndrome represents a huge potential public health issue because of its multiple clinical and societal consequences. Moreover, all these aspects have an impact on healthcare costs both for the patient and the society. Therefore, the implementation of effective and broadly applicable preventive and therapeutic interventions has become a medical and societal challenge for the growing number of older persons affected by sarcopenia and its disabling complications.

Habitual exercise plus dietary supplementation with milk fat globule membrane improves muscle function deficits via neuromuscular development in senescence-accelerated mice

We examined the effects of habitual exercise plus nutritional intervention through consumption of milk fat globule membrane (MFGM), a milk component, on aging-related deficits in muscle mass and function in senescence-accelerated P1 mice. Combining wheel-running and MFGM (MFGMEx) intake significantly attenuated age-related declines in quadriceps muscle mass (control: 318 ± 6 mg; MFGMEx: 356 ± 9 mg; P < 0.05) and in contractile force (1.4-fold and 1.5-fold higher in the soleus and extensor digitorum longus muscles, respectively). Microarray analysis of genes in the quadriceps muscle revealed that MFGMEx stimulated neuromuscular development; this was supported by significantly increased docking protein-7 (Dok-7) and myogenin mRNA expression. Treatment of differentiating myoblasts with MFGM-derived phospholipid or sphingolipid fractions plus mechanical stretching also significantly increased Dok-7 mRNA expression. These findings suggest that habitual exercise plus dietary MFGM improves muscle function deficits through neuromuscular development, and that phospholipid and sphingolipid in MFGM contribute to its physiological actions.

Sarcopenia

Sarcopenia, the loss of muscle mass and function with age, is highly relevant to clinical practice as it has been associated with a wide range of ageing outcomes including disability and shorter survival times. As such it is now a major focus for research and drug discovery. There has been recent progress in the development of consensus definitions for the diagnosis of sarcopenia, taking the form of measurements of muscle mass and strength or physical performance. These definitions form potential inclusion criteria for use in trials, although the optimum choice of outcome measures is less clear. Prevalence estimates using these new definitions vary, although they suggest that sarcopenia is a common (approximately 13% from one study) clinical problem in older people. A range of lifestyle factors have been investigated in regard to the development of this condition, and progressive resistance training is the most well-established intervention so far. There is also marked research interest in the role of diet, although so far the value of supplementation is less clear. Other potential treatments for sarcopenia include the angiotensin-converting enzyme inhibitors, with some evidence that they can improve physical performance in older people. Future research directions include an increased understanding of the molecular and cellular mechanisms of sarcopenia and the use of a life course approach to explore the possibility of earlier intervention and prevention.

New horizons in the pathogenesis, diagnosis and management of sarcopenia

Sarcopenia is the age-related loss of skeletal muscle mass and function. It is now recognised as a major clinical problem for older people and research in the area is expanding exponentially. One of the most important recent developments has been convergence in the operational definition of sarcopenia combining measures of muscle mass and strength or physical performance. This has been accompanied by considerable progress in understanding of pathogenesis from animal models of sarcopenia. Well-described risk factors include age, gender and levels of physical activity and this knowledge is now being translated into effective management strategies including resistance exercise with recent interest in the additional role of nutritional intervention. Sarcopenia is currently a major focus for drug discovery and development although there remains debate about the best primary outcome measure for trials, and various promising avenues to date have proved unsatisfactory. The concept of 'new tricks for old drugs' is, however, promising, for example, there is some evidence that the angiotensin-converting enzyme inhibitors may improve physical performance. Future directions will include a deeper understanding of the molecular and cellular mechanisms of sarcopenia and the application of a lifecourse approach to understanding aetiology as well as to informing the optimal timing of interventions.