Handgrip Strength and Vertical Jump and their Relationship with Body Fat in Hong Kong Chinese Children and Adolescents

Aim: To examine the associations of handgrip strength and vertical jump with gender, pubertal status and body composition,
and establish normal reference values of handgrip strength and vertical jump of Hong Kong Chinese children and adolescents.
Methods: This study included 1154 children and adolescents aged between 8 and 17 years, who participated in a territory-wide
cohort study. Data of anthropometry, pubertal status handgrip strength and vertical jump were collected. Percentile curves of
handgrip strength and vertical jump were constructed using the LMS method. General linear model was used to evaluate the effects
of age, sex, pubertal stage, body size, body fat and the possible 2-way interactions on handgrip strength and vertical jump.
Results: According to the international BMI cutoffs, the prevalence rate of overweight or obesity (20.7%) in our cohort of
children was similar to that obtained from previous local report. General linear model revealed that handgrip strength and vertical
jump increased with increasing age, and boys were significantly stronger than girls after aged 12 year or older. Among overweight/
obese children, those with high body fat had significantly lower handgrip strength than those with low body fat. A full model
including age, sex, BMI z score, body fat z score and age*sex interaction explained 67.8% and 60.1% of the variance of handgrip
strength and vertical jump respectively. Handgrip strength and vertical jump was positively associated with age, male sex and BMI
z score, but was negatively associated with body fat z score.
Conclusions: Classifying children’s weight status by BMI cutoffs, additional information on children’s body composition should
also be considered. Reference values for handgrip strength and vertical jump are established for Hong Kong Chinese children and
adolescents aged 8 to 17 years.