Allometric Grip Strength Norms for American Children.

Kocher, MH, Oba, Y, Kimura, IF, Stickley, CD, Morgan, CF, and Hetzler, RK. Allometric grip strength norms for American children. J Strength Cond Res 33(8): 2251-2261, 2019-To develop normative data from a large cohort of American school children (ages 6-18) for unscaled and allometrically scaled handgrip strength data that are uninfluenced by body size (body mass [BM] and stature [Ht]). Data (age, handgrip strength, BM, and Ht) were collected from the 2011-2012 and 2013-2014 National Health and Nutrition Examination Survey databases, resulting in 4,665 cases (2,384 boys and 2,281 girls). Multiple log-linear regressions were used to determine allometric exponents for BM and Ht separately for each age and sex to satisfy the common exponent and group difference principles described by Vanderburgh. Appropriateness of the allometric model was assessed through regression diagnostics, including normality and homoscedasticity of residuals. Allometrically scaled, ratio-scaled, and unscaled grip strength were then correlated with BM and Ht to examine the effectiveness of the procedure in controlling for body size. The data did not allow for development of a common exponent across age and sex that did not violate the common exponent and group difference principles. Correlations between allometrically scaled handgrip strength with BM and Ht were not significant (p ≤ 0.479) and approached zero, unlike correlations of unscaled handgrip strength with BM and Ht (p < 0.001 for all), indicating that allometric scaling was successful in removing the influence of body size. Allometric scaling handgrip strength by age and sex effectively controls for body size (Ht and BM) and perhaps maturation (Ht). The allometric exponents and normative values developed can be used to compare handgrip strength within age and sex while controlling for body size.

Allometric Grip Strength Norms for Children of Hawaiian Lineage.

The purpose of the study was to determine allometric exponents for scaling grip strength in children that effectively control for body mass (BM) and stature (Ht) and to develop normative grip strength data for Hawaiian children. One thousand, four hundred thirty-seven students (754 boys) from a rural community in Hawaii participated in this 5-year study, resulting in 2,567 data points. Handgrip strength, BM, and Ht were collected every year. Multiple log-linear regression was used to determine allometric exponents for BM and Ht. Appropriateness of the allometric model was assessed through regression diagnostics, including normality of residuals and homoscedasticity. Allometrically scaled, ratio-scaled, and unscaled grip strength were then correlated with BM and Ht to examine the effectiveness of the procedure in controlling for body size. Allometric exponents for BM and Ht were calculated separately for each age group of boys and girls to satisfy the common exponent and group difference principles described by Vanderburgh. Unscaled grip strength had moderate to strong positive correlations with BM and Ht (p ≤ 0.05 for all) for all age groups. Ratio-scaled handgrip strength had significant moderate to strong negative correlations with BM (p ≤ 0.05 for all) and, to a lesser extent, Ht (p ≤ 0.05 for 8- to 12-year-old boys; p ≤ 0.05 for 8- to 12- and 14-year-old girls). Correlations between allometrically scaled handgrip strength and BM and Ht were not significant and approached zero. This study was the first to allometrically scale handgrip strength for BM and Ht in Hawaiian children. Allometric scaling applied to grip strength provides a useful expression of grip strength free of the confounding influence of body size.

Autonomic Function is Associated with Fitness Level in HIV-Infected Individuals.

BACKGROUND: Cardiovascular fitness can improve autonomic function (AF) in human immunodeficiency virus (HIV)-infected individuals. METHODS: Cross-sectional study investigating relationship between AF and cardiovascular fitness in HIV+ individuals on antiretroviral therapy. Participants' (n=29) maximal oxygen consumption (VO2MAX) were assessed by graded exercise test and scaled allometrically, then divided into tertiles by fitness level (Unfit, Low-fit, and Moderately-fit). Heart rate variability (HRV) and the Autonomic Reflex Screen were used to assess AF. RESULTS: Median VO2MAX were 104.9, 130.5, and 150.2 mL•kg-.67•min-1 for Unfit (n=10), Low-fit (n=10), and Moderately-fit (n= 9) groups respectively (p<0.05). Positive correlations were found between VO2MAX and HRV (Spearman's rho range 0.383 to 0.553) were found. Quantitative Sudomotor Axon Reflex Test (QSART) Distal Leg volumes was lower in Unfit compared to Low-fit (p=0.007) and Moderately-fit groups (p=0.018). Unfit QSART total volumes was lower than Moderately-fit (p=0.014). CONCLUSION: A positive relationship existed between AF and fitness levels. HIV+ individuals could benefit from improved fitness.