Characterising sex-related differences in lower- and higher-threshold motor unit behaviour through high-density surface electromyography.

Emerging questions in neuromuscular physiology revolve around whether males and females share similar neural control in diverse tasks across a broad range of intensities. In order to explore these features, high-density electromyography was used to record the myoelectrical activity of biceps brachii during trapezoidal isometric contractions at 35% and 70% of maximal voluntary force (MVF) on 11 male and 13 female participants. Identified motor units were then classified as lower-threshold (recruited at ≤30%MVF) and higher-threshold (recruited at >30%MVF). The discharge rate, interspike interval variability, recruitment and derecruitment thresholds, and estimates of neural drive to motor neurons were assessed. Female lower-threshold motor units showed higher neural drive (P < 0.001), accompanied by higher discharge rate at recruitment (P = 0.006), plateau (P = 0.001) and derecruitment (P = 0.001). On the other hand, male higher-threshold motor units showed greater neural drive (P = 0.04), accompanied by higher discharge rate at recruitment (P = 0.005), plateau (P = 0.04) and derecruitment (P = 0.01). Motor unit discharge rate normalised by the recruitment threshold was significantly higher in female lower-threshold motor units (P < 0.001), while no differences were observed in higher-threshold motor units. Recruitment and derecruitment thresholds are higher in males across all intensities (P < 0.01). However, males and females have similar activation and deactivation strategies, as evidenced by similar recruitment-to-derecruitment ratios (P > 0.05). This study encompasses a broad intensity range to analyse motor unit sex-related differences, highlighting higher neural drive and discharge rates in female lower-threshold motor units, elevated recruitment and derecruitment thresholds in males, and convergences in activation and deactivation strategies. HIGHLIGHTS: What is the central question of the study? Do male and female motor units behave similarly in low- and high-intensity contractions? What is the main finding and its importance? Female motor units show higher discharge rates in low-intensity tasks and lower discharge rates in high-intensity tasks, with no differences in recruitment behaviour. A broader inter-spike interval variability was also observed in females. These findings underline that there are sex-specific differences concern the firing strategies based on task intensity.

Dietary Micronutrient and Mineral Intake in the Mediterranean Healthy Eating, Ageing, and Lifestyle (MEAL) Study.

BACKGROUND: Dietary vitamins and minerals are essential compounds for the proper functioning of metabolic enzymes, regulation of gene transcription, and powering the body’s defense against oxidative stress. The aim of the present study was to investigate micronutrient consumption separately by age and sex, major dietary sources, and percentage of individuals meeting the recommended requirements according to Italian (Livelli di Assunzione di Riferimento di Nutrienti (LARN)) and European (European Food Safety Agency (EFSA)) agencies. METHODS: Data were obtained from the Mediterranean Healthy Eating, Ageing, and Lifestyle (MEAL) study, which included a sample of 1838 individuals randomly collected in the city of Catania, southern Italy. A validated food frequency questionnaire was used to collect information on diet. RESULTS: Intake of vitamin A, vitamin C, and vitamin B group (except vitamin B9) was in line with other reports and was adequate according to the guidelines, while the percentage of individuals meeting the guidelines for vitamin D, vitamin E, and vitamin B9 was about 3%, 10%, and 40%, respectively. Among minerals, intake of iron, magnesium, and selenium was adequate for most of the sample, while the percentage of individuals meeting the recommendations for calcium, sodium, and potassium intake was about 20%, 8%, and 35%, respectively. CONCLUSIONS: An important percentage of the population would benefit from campaigns raising awareness of micronutrient deficiency or excessive consumption potentially affecting their health.

Macronutrient and Major Food Group Intake in a Cohort of Southern Italian Adults.

BACKGROUND: Dietary intake of macronutrient and foods is considered crucial to decrease the risk of diet-related non-communicable diseases. METHODS: The aim of this study was to describe the intake of major food groups and macronutrients in a random sample of 1838 southern Italian adults. RESULTS: No significant differences of macronutrient consumption between sexes were found. By contrast, younger individuals had significantly higher intake of animal protein than older ones. Men reported consuming significantly more total processed meats and less eggs than women; egg consumption significantly increased by age groups. Significantly lower intake of fruit in the younger age group compared to older ones was found. Various patterns of correlation between food groups were described. More than half of individuals reached the suggested recommendations for carbohydrate and fiber intake, and about two-thirds met the recommendations for total protein and cholesterol intake, while only a minority met for total fat intake. Total and plant protein, monounsaturated and omega-6 fatty acids, were significantly inversely related with BMI (body mass index), while trans fatty acids and cholesterol were directly correlated. A direct association with unprocessed meats and an inverse association with processed meats was also found. CONCLUSIONS: The overall findings suggest that relatively healthy dietary habits are common in southern Italy.

Acute severe male hypo-testosteronemia affects central motor command in humans.

PURPOSE: To indirectly evaluate the effect of androgens on neuromuscular system in humans we analyzed if an induced short-term hypogonadal state (serum total testosterone-TT<2.3ng/ml) may affect central drive to skeletal muscle and/or muscle neuro-mechanical performance. METHODS: We compared voluntary and electrically evoked muscle sEMG signals from biceps brachii in nine hypogonadal male volunteers (Hypo) and in ten healthy controls (Cont). Serum TT and dihydrotestosterone (DHT) were assayed. RESULTS: With respect to Hypo, Cont exhibited significantly higher median frequency content (MDF) at any angular velocity; normalized MDF [95.9% (SD=23.3) vs 73.8% (SD=9.3)]; muscle fiber conduction velocity (CV) from lowest to highest angular velocities; initial MDF at fatigue test [91.78Hz (SD=22.03) vs 70.94Hz (SD=11.06)] as well as was the normalized slope [-0.64 (SD=0.14 vs -0.5 (SD=0.11)]. In the non-fatigued state, Hypo showed a slower single twitches time to peak (TTP). In Cont, half relaxation time (HRT) decreased after fatigue while increased in Hypo (p<0.05 between groups). A significant correlation between both TT and dihydrotestosterone with MDF and CV was found during voluntary contractions only. CONCLUSIONS: A brief exposure to very low serum TT concentration in males seem to determine a reduced excitability of the NM system which, in turn, would favor a predominant recruitment of slow twitch MUs.

The Burden of Depressive and Bipolar Disorders in Celiac Disease.

AIMS: to measure the association between Celiac Disease (CD) and affective disorders, particularly Bipolar Disorder (BD), since it has not been studied yet, and to measure how much the quality of life (QoL) of a person with CD is affected by comorbidity with these disorders. DESIGN: Case-control study. CASES: 60 consecutive patients with CD. CONTROLS: 240 subjects without CD, randomly selected after sex- and age-matching from a database of an epidemiological study. Psychiatric diagnoses according to DSM-IV carried out by physicians using structured interview tools (ANTAS-SCID). QoL was measured by means of SF-12. RESULTS: The lifetime prevalence of Major Depressive Disorder (MDD) was higher in CD than in controls (30.0% vs 8.3%, P<0.0001) as well as Panic Disorder (PD) (18.3% vs 5.4%, P<0.001) and BD (4.3% vs 0.4%, P<0.005). Patients with CD show a lower mean score than controls on SF12 (35.8±5.7 vs. 38.2±6.4; p=0.010), but those without comorbidity with MDD, PD and BD do not. The attributable burden of CD in worsening QoL - when comorbid with these disorders - was found comparable to that of serious chronic diseases like Wilson's Disease, and lower than Multiple Sclerosis only. CONCLUSION: MDD, PD and BD are strictly associated with CD. The comorbidity with these disorders is the key determinant of impaired quality of life in CD. Thus a preventive action on mood and anxiety disorders in patients suffering from CD is required. Moreover a screening for CD in people with affective disorders and showing key symptoms or family history of CD is recommended.