Normative Reference Values for Handgrip Strength in Colombian Schoolchildren: The FUPRECOL Study.

Ramírez-Vélez, R, Morales, O, Peña-Ibagon, JC, Palacios-López, A, Prieto-Benavides, DH, Vivas, A, Correa-Bautista, JE, Lobelo, F, Alonso-Martínez, AM, and Izquierdo, M. Normative reference values for handgrip strength in Colombian schoolchildren: the FUPRECOL study. J Strength Cond Res 31(1): 217-226, 2017-The primary aim of this study was to generate normative handgrip (HG) strength data for 10 to 17.9 year olds. The secondary aim was to determine the relative proportion of Colombian children and adolescents that fall into established Health Benefit Zones (HBZ). This cross-sectional study enrolled 7,268 schoolchildren (boys n = 3,129 and girls n = 4,139, age 12.7 [2.4] years). Handgrip was measured using a hand dynamometer with an adjustable grip. Five HBZs (Needs Improvement, Fair, Good, Very Good, and Excellent) have been established that correspond to combined HG. Centile smoothed curves, percentile, and tables for the third, 10th, 25th, 50th, 75th, 90th, and 97th percentile were calculated using Cole's LMS method. Handgrip peaked in the sample at 22.2 (8.9) kg in boys and 18.5 (5.5) kg in girls. The increase in HG was greater for boys than for girls, but the peak HG was lower in girls than in boys. The HBZ data indicated that a higher overall percentage of boys than girls at each age group fell into the "Needs Improvement" zone, with differences particularly pronounced during adolescence. Our results provide, for the first time, sex- and age-specific HG reference standards for Colombian schoolchildren aged 9-17.9 years.

Acute effects of high-intensity interval, resistance or combined exercise protocols on testosterone - cortisol responses in inactive overweight individuals.

The purpose of this study was to compare the hormonal responses to one session of high-intensity interval training (HIIT, 4 × 4 min intervals at 85-95% maximum heart rate [HRmax], interspersed with 4 min of recovery at 75-85% HRmax), resistance training (RT at 50-70% of one repetition maximum 12-15 repetitions per set with 60s of recovery) or both (HIIT+RT) exercise protocol in a cohort of physical inactivity, overweight adults (age 18-30 years old). Randomized, parallel-group clinical trial among fifty-one men (23.6 ±â€¯3.5 yr; 83.5 ±â€¯7.8 kg; 28.0 ±â€¯1.9 kg/m2), physical inactivity (i.e., <150 min of moderate-intensity exercise per week for >6 months), with abdominal obesity (waist circumference ≥90 cm) or body mass index ≥25 and ≤30 kg/m2 were randomized to the following 4 groups: high-intensity interval training (HIIT, n = 14), resistance training (RT, n = 12), combined high-intensity interval and resistance training (HIIT+RT, n = 13), or non-exercising control (CON, n = 12). Cortisol, total- and free-testosterone and total-testosterone/cortisol-ratio (T/C) assessments (all in serum) were determined before (pre) and 1-min post-exercise for each protocol session. Decreases in cortisol levels were -57.08 (95%CI, -75.58 to -38.58; P = 0.001; ɳ2 = 0.61) and - 37.65 (95%CI, -54.36 to -20.93; P = 0.001; ɳ2 = 0.51) in the HIIT and control group, respectively. Increases in T/C ratio were 0.022 (95%CI, 0.012 to 0.031; P = 0.001; ɳ2 = 0.49) and 0.015 (95%CI, 0.004 to 0.025; P = 0.007; ɳ2 = 0.29) in the HIIT and control group, respectively. In per-protocol analyses revealed a significant change in cortisol levels [interaction effect F(7.777), ɳ2 = 0.33] and T/C ratio [interaction effect F(5.298), ɳ2 = 0.25] between groups over time. Additionally, we showed that in both the intention-to-treat (ITT) and per protocol analyses, HIIT+RT did not change serum cortisol, total or free testosterone. The present data indicate a HIIT reduced cortisol and increased total-testosterone/cortisol-ratio levels significantly in physically inactive adults. Further study is required to determine the biological importance of these changes in hormonal responses in overweight men.

Acute Effects of High Intensity, Resistance, or Combined Protocol on the Increase of Level of Neurotrophic Factors in Physically Inactive Overweight Adults: The BrainFit Study.

The purpose of this study was to compare the neurotrophic factor response following one session of high-intensity exercise, resistance training or both in a cohort of physically inactive overweight adults aged 18-30 years old. A randomized, parallel-group clinical trial of 51 men (23.6 ± 3.5 years; 83.5 ± 7.8 kg; 28.0 ± 1.9 kg/m2) who are physically inactive (i.e., < 150 min of moderate-intensity exercise per week or IPAQ score of <600 MET min/week for >6 months) and are either abdominally obese (waist circumference ≥90 cm) or have a body mass index, BMI ≥25 and ≤ 30 kg/m2 were randomized to the following four exercise protocols: high-intensity exercise (4 × 4 min intervals at 85-95% maximum heart rate [HRmax] interspersed with 4 min of recovery at 75-85% HRmax) (n = 14), resistance training (12-15 repetitions per set, at 50-70% of one repetition maximum with 60 s of recovery) (n = 12), combined high-intensity and resistance exercise (n = 13), or non-exercising control (n = 12). The plasma levels of neurotrophin-3 (NT-3), neurotrophin-4 (also known as neurotrophin 4/5; NT-4 or NT-4/5), and brain-derived neurotrophic factor (BDNF) were determined before (pre-exercise) and 1-min post-exercise for each protocol session. Resistance training induced significant increases in NT-3 (+39.6 ng/mL [95% CI, 2.5-76.6; p = 0.004], and NT-4/5 (+1.3 ng/mL [95% CI, 0.3-2.3; p = 0.014]), respectively. Additionally, combined training results in favorable effects on BDNF (+22.0, 95% CI, 2.6-41.5; p = 0.029) and NT-3 (+32.9 ng/mL [95% CI, 12.3-53.4; p = 0.004]), respectively. The regression analysis revealed a significant positive relationship between changes in BDNF levels and changes in NT-4/5 levels from baseline to immediate post-exercise in the combined training group (R2 = 0.345, p = 0.034) but not the other intervention groups. The findings indicate that acute resistance training and combined exercise increase neurotrophic factors in physically inactive overweight adults. Further studies are required to determine the biological importance of changes in neurotrophic responses in overweight men and chronic effects of these exercise protocols. TRIAL REGISTRATION: ClinicalTrials.gov, NCT02915913 (Date: September 22, 2016).