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Cadmium, a toxic heavy metal, is ubiquitous in the environment. No previous research has evaluated the relationship of blood and urine cadmium levels with muscle strength measured by isokinetic knee extensor strength. This analysis included participants who were aged 50 years or older and had measurements of cadmium in blood (n = 2052) and urine (n = 811) from the National Health and Nutrition Examination Survey. Blood and urine cadmium levels were assessed by atomic absorption spectrometry and inductively coupled plasma-mass spectrometry, respectively. Isokinetic dynamometry was used to assess knee extensor strength (peak force). Linear regression models were used to examine the association between cadmium exposure and peak force, with adjustment for potential confounders. The median values (25–75th percentiles) of blood cadmium and creatinine-corrected urine cadmium were 0.50 μg/L (0.40–0.70) and 0.43 μg/g (0.27–0.71), respectively. After adjusting for potential confounders, linear dose-response relationships of peak force with blood and urine cadmium concentrations were observed in the present study. Compared to participants in the highest quartile of blood cadmium and urine cadmium, the peak force decreased by 6.99 Newton (95% CI: −21.96, 7.98) and 26.84 Newton (95% CI: −44.34, −9.34) in participants in the lowest quartiles, respectively. The observed associations were more evident among men participants. Our findings suggest that the cadmium levels have a dose response relationship with decreased muscle strength measured by isokinetic knee extensor strength in middle aged and older adults. Further longitudinal investigations are required to disentangle these complexities on this issue. [ABSTRACT FROM AUTHOR]

Human beings are exposed to heavy metals through various ways in daily life. However, the effect of heavy metal mixtures on muscle strength in children and adolescents remains unclear. We aimed to investigate the relationship of exposure to heavy metal mixtures (barium, cadmium, cobalt, manganese, molybdenum, lead, antimony, strontium, tin, thallium, tungsten, uranium, and cesium) with muscle strength in children and adolescents. A total of 1357 (boys, 50.8%) participants aged between 8 and 17 were extracted from the National Health and Nutrition Examination Surveys 2011–2014. Urine metals were measured by inductively coupled plasma-mass spectrometry. Muscle strength was measured through a grip test using a handgrip dynamometer. Weighted quantile sum regression was performed to estimate the mixture effect of urinary metals on muscle strength. After adjusting for potential confounders, comparing participants in the highest versus lowest quartiles of cobalt, molybdenum, lead, antimony, strontium, thallium, and cesium, the handgrip strength decreased by − 4.48 kg (95% CI: − 6.93, − 2.03), − 6.13 kg (− 8.76, − 3.51), − 2.26 kg (− 4.22, − 0.30), − 2.38 kg (− 4.68, − 0.08), − 2.29 kg (− 4.45, − 0.13), − 4.78 kg (− 7.13, − 2.44), and − 5.68 kg (− 9.20, − 2.17), respectively. Furthermore, exposure to a mixture of metals were also significantly associated with decreased muscle strength (β: − 2.62 kg; 95% CI: − 3.71, − 1.54). Findings from the present study suggest that higher heavy metal exposure and the exposure levels of a mixture of metals in urine are inversely related to handgrip strength, implying that children's grip strength is not entirely explained by energy intake or lack of exercise, but may be related to environmental pollutants. [ABSTRACT FROM AUTHOR]