Field-based versus laboratory-based estimates of muscle quality index in adolescents with and without Down syndrome.

BACKGROUND: Low muscle quality index (MQI) is a potential risk of developing functional impairments in older people. However, considering that individuals with Down syndrome (DS) present with a faster decline in biological aging, an investigation on MQI in individuals with DS is necessary. The aims of this present cross-sectional study were to compare (1) MQI between adolescents with and without DS and (2) evaluate laboratory versus field-based estimates of MQI. METHODS: Fifty-six adolescents were recruited and separated into two groups: DS (n = 30, 13 boys and 17 girls; age: 12.38 ± 3.07 years) and a control (non-DS; n = 26, 9 boys and 17 girls; age: 12.46 ± 2.88 years). Laboratory MQI was derived from the ratio of grip strength to arm muscle mass (in kg) measured by dual-energy X-ray absorptiometry (DXA). Field-based MQI was quantified from the ratio of hand grip strength (HGS) to body mass index (BMI). For statistical analyses, a two-way ANOVA was conducted for group comparisons, and a Pearson correlation was used to test the association between field MQI and laboratory MQI. RESULTS: Adolescents with DS displayed lower field (P = 0.001), laboratory MQI estimates (P = 0.001) and HGS (P = 0.001) as compared non-DS. Also, there was a strong correlation effect between field MQI and laboratory MQI estimates (P < 0.001, R = 0.81). CONCLUSION: Adolescents with DS have lower field and laboratory MQI compared with adolescents without DS. Simpler field MQI might be used in daily clinical practice, with special attention to those with DS.

Irisin Levels Are not Associated to Resistance Training-Induced Alterations in Body Mass Composition in Older Untrained Women with and without Obesity.

OBJECTIVE: The present study aimed to determine whether Irisin levels are correlated with body composition changes following 16 weeks of resistance training (RT) in older women with and without obesity. Design, Setting, Participants, Intervention: We recruited 49 inactive women (n = 23, non-obese: < 41.0% and n = 26, obese: ≥ 41.0% of body fat) aged 61-68 years to perform 16-week of RT consisting of 10 exercises (three sets of 10 exercises, 6-12 repetitions maximum and 1-min and 30-s rest intervals between sets and exercises, respectively) with two sessions per week. MEASUREMENTS: Before and after the intervention period, blood samples were collected to determine Irisin levels and body composition (percentage body fat and fat-free mass) was measured by dual energy x-ray absorptiometry. RESULTS: Circulating Irisin displayed a decrease for the non-obese group as compared with pre-intervention and obese group (p = 0.01 and p = 0.04, respectively), with no change for the obese group (p = 0.79). In addition, fat mass displayed a significant reduction (p < 0.05) following the training period only for the obese group. Furthermore, there was no association between changes in circulating Irisin with body mass index, body fat, fat-free mass and muscle strength. There was an increase in muscle strength (p < 0.05), regardless of obesity status. CONCLUSION: The modulation of body composition and muscle strength induced by 16-week of resistance training in older women with and without obesity is not associated with changes in circulating Irisin levels.

Correlation between acute and chronic 24-hour blood pressure response to resistance training in adult women.

The purpose of the present study was to correlate the acute and chronic decrease in blood pressure (BP) following resistance training (RT). 13 normotensive women (18-49 years) completed an acute whole body RT session with 3 sets of 10 repetitions at 60% 1RM and then 8 weeks of RT as follows: 3/week, 3 sets of 8-12 repetitions maximum. Systolic (SBP) and diastolic BP (DBP) were measured up to 60 min and 24 h following RT (acute and chronic). The greatest acute decrease of SBP (108.5±7.0 mmHg) and DBP (71.5±6.4 mmHg) values over the 60-min period were reduced compared to pre-exercise (117.3±11.7 and 79.3±8.2 mmHg, respectively; p<0.05). The chronic effect on resting BP was observed only for those presenting acute post-exercise hypotension (PEH). The change in both SBP and DBP following acute RT was correlated with the chronic change in resting SBP and DBP (r>0.5; p≤0.05). The change in 24 h BP after acute RT was correlated with the chronic reduction in SBP (r=0.74) and DBP (r=0.80). The magnitude of PEH is a promising candidate for the prediction of individual BP-related training efficacy.