Grip strength positively correlates with blood pressure in individuals with abnormal adiposity

Although strong positive correlations exist between grip strength and cardiovascular health, the association between grip strength and blood pressure (BP) is less clear. In this regard, a more precise relationship between grip strength and BP may be revealed by considering adiposity. We examined the association between grip strength and BP in 9424 individuals aged 18–92 years, while controlling for or stratifying by body mass index (BMI) or body fat (BF)%. Grip strength, BP and BF% were determined using dynamometry, sphygmomanometry and dual-energy x-ray absorptiometry. Overall, those with elevated BP had greater grip strength than those with normal BP (39.17 kg vs 38.38 kg, p < 0.001); however, following stratification this was only observed in overweight or obese individuals (42.08 kg vs 41.10 kg, p = 0.003 and 41.34 kg vs 40.03 kg, p = 0.033), and those within the highest BF% tertile (37.95 kg vs 36.52 kg, p < 0.001). Overall, higher grip strength was associated with an increased odds for elevated BP (OR = 1.014, 95% CI = 1.004–1.024, p = 0.004); however, after stratification the increased odds was only observed in overweight or obese individuals (OR = 1.025, 95% CI = 1.010–1.039, p < 0.001 and OR = 1.018, 95% CI = 1.004–1.031, p = 0.010), and those within the highest BF% tertile (OR = 1.036, 95% CI = 1.022–1.051, p < 0.001). Individuals with low grip strength and high BF% had lower odds for elevated BP (OR = 0.514, 95% CI = 0.341–0.775, p = 0.002), whereas those with low grip strength and low BF% had higher odds for elevated BP (OR = 2.162, 95% CI = 1.026–4.555, p = 0.043). Our findings show that higher grip strength is related to higher BP in overweight or obese individuals, or those with a high BF%. Having a BMI < 25 kg/m2 or lower BF% may neutralise this association. (Figure presented.)

The relationship between active travel to school and health-related fitness in children and adolescents: a systematic review

Background: Active travel to school (ATS) has been identified as an important source of physical activity for youth. However, the relationship between ATS and health-related fitness (HRF) among youth remains unclear. Methods: A systematic search of seven electronic databases (EMBASE, OVID MEDLINE, PsycINFO, PubMed, Scopus, SPORTDiscus and TRIS on line) was conducted in December 2009 and studies published since 1980 were considered for inclusion. Results: Twenty seven articles were identified that explored the relationship between ATS and the following aspects of HRF: weight status/body composition, cardiorespiratory fitness, muscular fitness and flexibility. Forty-eight percent of the studies that examined the relationship between ATS and weight status/body composition reported significant associations, this increased to 55% once poor quality studies were removed. Furthermore, the findings from five studies, including one longitudinal study, indicate that ATS is positively associated with cardiorespiratory fitness in youth. However, the evidence for the relationships between ATS and muscular fitness or flexibility is equivocal and limited by low study numbers. Conclusions: There is some evidence to suggest that ATS is associated with a healthier body composition and level of cardiorespiratory fitness among youth. Strategies to increase ATS are warranted and should be included in whole-of-school approaches to the promotion of physical activity

Plasma C-terminal agrin fragment concentrations across adulthood: reference values and associations with skeletal muscle health

Background Increasing interest surrounds the utility of blood-based biomarkers for diagnosing sarcopenia. C-terminal agrin fragment (CAF), a marker of neuromuscular junction stability, is amongst the most promising candidates; however, a dearth of reference data impedes the incorporation of its use in public health settings. This study aimed to establish reference values for plasma CAF concentrations across adulthood in a large, well-characterized cohort of healthy adults; and comprehensively examine the association between plasma CAF levels and skeletal muscle health. Methods One thousand people aged between 18 and 87 years took part in this study (mean age = 50.4 years; 51% females). Body composition and muscle strength were examined using DXA and hand dynamometry. Plasma CAF concentrations were measured, in duplicate, using commercially available ELISA kits. Sarcopenia and individual sarcopenia signatures [low skeletal muscle index (SMI) only/low grip strength only] were classified using the EWGSOP2 algorithm. Results Detailed reference CAF values, according to sex and age, are presented. A significant but modest age-related increase in plasma CAF concentration was observed (P = 0.018). Across adulthood, CAF concentrations were negatively associated with grip strength and SMI (both P < 0.001). In people ≥50 years old, CAF concentrations were 22.6% higher in those with sarcopenia (P < 0.001), 11.3% higher in those with low SMI (P = 0.006) and 9.6% higher in those with low grip strength (P = 0.0034), compared with controls. People in the highest CAF concentration quartile, had 3.25 greater odds for sarcopenia (95% CI = 1.41–7.49, P = 0.005), 2.76 greater odds for low SMI (95% CI = 1.24–5.22, P = 0.012), and 2.56 greater odds for low grip strength (95% CI = 1.07–5.57, P = 0.037), compared with those in the lowest quartile. People with a CAF Z-score ≥2 had 9.52 greater odds for sarcopenia (95% CI = 3.01–30.05, P < 0.001) compared with a Z-score <1. Plasma CAF concentration had an acceptable level of diagnostic accuracy for sarcopenia (AUC = 0.772, 95% CI = 0.733–0.807, P < 0.001). Conclusions The reference values presented herein may guide the clinical interpretation of circulating CAF and help identify people at risk of poor skeletal muscle outcomes for inclusion in therapeutic interventions. Our findings add clarity to existing data, demonstrating a robust relationship between circulating CAF and skeletal muscle integrity in the largest adult cohort to date, and support the use of CAF as an accessible, cost-effective screening tool for sarcopenia. However, further research into the prognostic utility of plasma CAF, and the establishment of normative data from other populations, are urgently needed if routine CAF screening is to be embedded into public healthcare settings

Grip strength performance from 9431 participants of the GenoFit study: normative data and associated factors

Weak grip strength is a strong predictor of multiple adverse health outcomes and an integral diagnostic component of sarcopenia. However, the limited availability of normative data for certain populations impedes the interpretation of grip performance across adulthood. This study aimed to establish normative data and low grip strength thresholds in a large adult population, and to examine associations between grip strength and clinically relevant health variables. A total of 9431 adults aged between 18 and 92 years participated in this study (mean age: 44.8 ± 13.4 years; 57% females). Grip strength, body composition, and cardiorespiratory (CR) fitness were assessed using hand dynamometry, dual-energy x-ray absorptiometry and physical work capacity tests, respectively. Low grip strength was established according to criteria of the European Working Group on Sarcopenia in Older People. Normative data and t-scores, stratified by sex and age groups, are presented. Grip performance was associated with lean mass, skeletal muscle index (SMI), fat mass, CR fitness, bone mineral density (BMD), android/gynoid ratio, disease prevalence and physical activity levels (all p < 0.001) after controlling for multiple potential confounders. Individuals with weak grip strength had lower lean mass, SMI, CR fitness (all p < 0.001) and BMD (p = 0.001), and higher disease prevalence (p < 0.001), compared to healthy controls, although sex-specific differences were observed. Grip strength has practical screening utility across a range of health domains. The normative data and grip strength thresholds established in this study can guide the clinical interpretation of grip performance and facilitate timely therapeutic strategies targeting sarcopenia

Plasma neurofilament light levels associate with muscle mass and strength in middle-aged and older adults: findings from GenoFit

Background: Efforts to enhance diagnostic measures for sarcopenia have led to an increased focus on the screening utility of blood-based biomarkers. In this regard, circulating neurofilament light chain (NfL) levels are a potent indicator of axonal damage and have been linked with several neurological disorders. However, despite the strong neurogenic contribution to skeletal muscle health, no studies have explored the relevance of NfL concentrations to sarcopenia. With that in mind, this study aimed to examine the association between plasma NfL concentration and sarcopenic domains. Methods: Three hundred adults aged between 50 and 83 years participated to this study (male participants, n = 150; mean age: 64.2 ± 8.7 years and female participants, n = 150; mean age: 63.9 ± 8.3 years). Body composition was assessed using dual-energy X-ray absorptiometry, and a skeletal muscle index (SMI) was calculated. Muscle strength was assessed with hand dynamometry. Sarcopenia was classified using the European Working Group on Sarcopenia in Older People criteria. Plasma NfL concentration was determined using a highly sensitive, enzyme-linked immunosorbent assay. Results: Neurofilament light chain levels were associated with grip strength and SMI (P = 0.005 and P = 0.045, respectively) and were significantly elevated in sarcopenic individuals, compared with non-sarcopenic participants (P < 0.001). Individuals with pre-sarcopenia (either low grip strength or low SMI) had significantly higher NfL levels, compared with healthy controls (P = 0.001 and P = 0.006, respectively). Male participants with either low grip strength or low SMI had significantly raised NfL levels (P = 0.006 and P = 0.002, respectively), while in female participants, NfL concentrations were significantly elevated only in those with low grip strength (P = 0.049). NfL concentration displayed acceptable diagnostic accuracy for sarcopenia (area under the curve = 0.726, P < 0.001). Conclusions: Our study clearly demonstrates the indicative pertinence of circulating NfL levels to sarcopenic domains, supporting its potential use as a biomarker of sarcopenia. More studies are needed, however, to further illuminate the diagnostic value of circulating NfL. Future research should explore whether NfL levels are more powerfully linked with muscle strength than mass and whether sex mediates the relevance of NfL concentrations to sarcopenic phenotypes

Low Volume, Home-Based Weighted Step Exercise Training Can Improve Lower Limb Muscle Power and Functional Ability in Community-Dwelling Older Women

Stepping exercise can be used as a scalable form of high intensity exercise to enhance important aspects of physical fitness in older populations. The addition of supplementary weights increases the resistive element of stepping, with the potential for training improvements in muscular strength, power, and functional abilities alongside other fitness outcomes. The aim of this study was to evaluate the effects of a low-volume, home-based weighted step exercise programme on muscular strength, power, and functional ability in previously inactive community-dwelling older women. Eleven participants, aged between 65–74 years, independently completed a six-week individualised and progressive step exercise training programme wearing a weighted vest. Knee extensor strength, lower limb power output, and physical function using a battery of functional tests were measured at baseline, following a 6-week control period, and again following the 6-week training programme. Following training, lower limb power output improved by 10–11% (p < 0.05) and was accompanied by a corresponding 9% (p < 0.01) improvement in stair climb time and 10% (p < 0.01) improvement in normalised stair climbing power, highlighting the beneficial effects of weighted stepping for transferable improvements in functional fitness. The magnitude of observed training improvements suggest that weighted step training has the potential to prolong independence and prevent age-related health conditions such as sarcopenia

The effects of aerobic exercise training at two different intensities in obesity and type 2 diabetes: implications for oxidative stress, low-grade inflammation and nitric oxide production

Aims To investigate the effect of 16 weeks of aerobic training performed at two different intensities on nitric oxide (tNOx) availability and iNOS/nNOS expression, oxidative stress (OS) and inflammation in obese humans with or without type 2 diabetes mellitus (T2DM). Methods Twenty-five sedentary, obese (BMI > 30 kg/m(2)) males (52.8 +/- 7.2 years); 12 controls versus 13 T2DM were randomly allocated to four groups that exercised for 30 min, three times per week either at low (Fat-Max; 30-40 % VO2max) or moderate (T-vent; 55-65 % VO2max) intensity. Before and after training, blood and muscle samples (v. lateralis) were collected. Results Baseline erythrocyte glutathione was lower (21.8 +/- 2.8 vs. 32.7 +/- 4.4 nmol/ml) and plasma protein oxidative damage and IL-6 were higher in T2DM (141.7 +/- 52.1 vs. 75.5 +/- 41.6 nmol/ml). Plasma catalase increased in T2DM after T-vent training (from 0.98 +/- 0.22 to 1.96 +/- 0.3 nmol/min/ml). T2DM groups demonstrated evidence of oxidative damage in response to training (elevated protein carbonyls). Baseline serum tNOx were higher in controls than T2DM (18.68 +/- 2.78 vs. 12.34 +/- 3.56 mu mol/l). Training at T-vent increased muscle nNOS and tNOx in the control group only. Pre-training muscle nNOS was higher in controls than in T2DMs, while the opposite was found for iNOS. No differences were found after training for plasma inflammatory markers. Conclusion Exercise training did not change body composition or aerobic fitness, but improved OS markers, especially when performed at T-vent. Non-diabetics responded to T-vent training by increasing muscle nNOS expression and tNOx levels in skeletal muscle while these parameters did not change in T2DM, perhaps due to higher insulin resistance (unchanged after intervention)

Plasma C-Terminal Agrin Fragment as an early biomarker for Sarcopenia: results from the GenoFit Study

Barriers associated with direct muscle quantification have prevented a consistent implementation of therapeutic measures for sarcopenia. Recently, the relevance of circulating C-terminal agrin fragment (CAF) as an accessible screening method alternative for sarcopenia has gained credence. Accordingly, this study aimed to verify the pertinence of plasma CAF as a biomarker for sarcopenia. Three hundred healthy adults aged between 50 and 83 years took part in this study. Sarcopenia was diagnosed according to the European Working Group on Sarcopenia in Older People criteria. Body composition was assessed using dual-energy x-ray absorptiometry, while muscle strength was examined using hand dynamometry. Plasma CAF concentrations were determined using a commercially available ELISA kit. CAF concentrations were significantly associated with appendicular lean mass (ALM), but not grip strength (p =. 028, p =. 575, respectively). Plasma CAF concentrations were significantly elevated in sarcopenic individuals compared to nonsarcopenic (p <. 001). Overall, individuals with low grip strength or low ALM displayed significantly higher CAF levels compared to healthy controls, after adjusting for age and body mass index (p =. 027, p =. 003, respectively). In males, those with low grip strength or low ALM had significantly elevated CAF levels (p =. 039, p =. 027, respectively), while in females, only those with low ALM had significantly raised CAF concentrations, compared to healthy controls (p =. 035). Our findings illuminate the potential relevance of CAF as an accessible biomarker for skeletal muscle health. CAF determination may enhance clinical practice by facilitating more widespread treatment strategies for sarcopenia. Nevertheless, future research is needed to confirm the diagnostic pertinence of CAF concentrations in screening for sarcopenia

Genes encoding agrin (AGRN) and neurotrypsin (PRSS12) are associated with muscle mass, strength and plasma C-terminal agrin fragment concentration

Although physiological data suggest that neuromuscular junction (NMJ) dysfunction is a principal mechanism underpinning sarcopenia, genetic studies have implicated few genes involved in NMJ function. Accordingly, we explored whether genes encoding agrin (AGRN) and neurotrypsin (PRSS12) were associated with sarcopenia phenotypes: muscle mass, strength and plasma C-terminal agrin fragment (CAF). PhenoScanner was used to determine if AGRN and/or PRSS12 variants had previously been implicated with sarcopenia phenotypes. For replication, we combined genotype from whole genome sequencing with phenotypic data from 6715 GenoFit participants aged 18–83 years. Dual energy X-ray absorptiometry assessed whole body lean mass (WBLM) and appendicular lean mass (ALM), hand dynamometry determined grip strength and ELISA measured plasma CAF in a subgroup (n = 260). Follow-up analyses included eQTL analyses, carrier analyses, single-variant and gene-burden tests. rs2710873 (AGRN) and rs71608359 (PRSS12) associate with muscle mass and strength phenotypes, respectively, in the UKBB (p = 8.9 × 10−6 and p = 8.4 × 10−6) and GenoFit cohort (p = 0.019 and p = 0.014). rs2710873 and rs71608359 are eQTLs for AGRN and PRSS12, respectively, in ≥ three tissues. Compared to non-carriers, carriers of rs2710873 had 4.0% higher WBLM and ALM (both p < 0.001), and 9.5% lower CAF concentrations (p < 0.001), while carriers of rs71608359 had 2.3% lower grip strength (p = 0.034). AGRN and PRSS12 are associated with muscle strength and mass in single-variant analyses, while PRSS12 has further associations with muscle strength in gene-burden tests. Our findings provide novel evidence of the relevance of AGRN and PRSS12 to sarcopenia phenotypes and support existing physiological data illustrating the importance of the NMJ in maintaining muscle health during ageing

Handgrip strength asymmetry as a new biomarker for sarcopenia and individual sarcopenia signatures

Background: Although handgrip strength (HGS) asymmetry has clinical screening utility, its relevance to sarcopenia is unknown. This study examined the relationship between HGS asymmetry and sarcopenia signatures, and explored the relevance of circulating neural/neuromuscular markers. Methods: 9403 individuals aged 18–92 years participated in this study. Maximal HGS and skeletal muscle index (SMI) were determined using hand dynamometry and DXA. Sarcopenia was diagnosed upon the presence of low HGS and low SMI, according to cohort-specific thresholds. Plasma biomarkers were measured by ELISA in a sub-group of 269 participants aged 50–83 years. Asymmetry was determined as the highest recorded HGS divided by the highest recorded HGS of the opposite hand. Individuals with a ratio > 1.10 were classified as having asymmetrical HGS. Results: Subjects with asymmetrical HGS had significantly lower SMI (7.67 kg/m2 vs 7.71 kg/m2, p = 0.004) and lower HGS (37.82 kg vs 38.91 kg, p < 0.001) than those with symmetrical HGS. In those aged ≥ 50 years asymmetrical HGS was associated with 2.67 higher odds for sarcopenia [95% confidence interval: (CI) = 1.557–4.561, p < 0.001], 1.83 higher odds for low HGS only (CI 1.427–2.342, p < 0.001), and 1.79 higher odds for low SMI only (CI 1.257–2.554, p = 0.001). HGS asymmetry demonstrated acceptable diagnostic accuracy for sarcopenia (AUC = 0.727, CI 0.658–0.796, p < 0.001). Plasma neural cell adhesion molecule concentrations were 19.6% higher in individuals with asymmetrical HGS (185.40 ng/mL vs 155.00 ng/mL, p < 0.001) than those with symmetrical HGS. Discussion: Our findings demonstrate the utility of HGS asymmetry as a screening tool that may complement existing strategies seeking to combat sarcopenia. Biomarker analyses suggest that heightened denervation may be an important aetiological factor underpinning HGS asymmetry