Mechanography in childhood: references for force and power in counter movement jumps and chair rising tests.

OBJECTIVE: We sought to procure age- and gender- related reference data and study the characteristics of body weight related peak force (pFrel), body mass related peak power (pPrel) for counter movement jumps (single two-legged jumps, s2LJ) and chair rising tests (CRT) in children. METHODS: We examined 868 healthy participants (436 female) aged 3 to 19 years. Weight-related results of the s2LJ and CRT Mechanography parameters were reported. RESULTS: pPrel during s2LJ (pPrel(s2LJ)) increased linearly with age for males age 5 to 19 and female age 5 to 11 at a rate of 4.6 W/kg per year. pPrel(s2LJ) for females age 12 to 19 increased only by 2.5 W/kg. CRT time per repetition was 1.065 s, independent of age and gender. pPrel per body mass during the rise phase (pPrel(CRT)) showed similar but smaller age and gender relations as peak power during s2LJ. pFrel was 2.5 g (multiples of earth's gravity) for s2LJ and 1.5 g for CRT. CONCLUSION: This data from normal children from a healthy Caucasian population provide reference values for tests that reflect everyday motor function.

Mechanography in childhood: references for grip force, multiple one-leg hopping force and whole body stiffness.

OBJECTIVE: We sought to study and procure reference values for weight-related maximum isometric grip force (MIGF), maximum voluntary force in relation to body weight (Fmvrel) and peak whole body stiffness (pKwb) in multiple one-legged hopping (m1LH) in childhood. METHODS: We examined 868 children and adolescents (436 female) aged 3 to 19 yrs. Weight related results are reported as multiples of earth's gravity (g). RESULTS: MIFG and Fmv(m1LH) are highly linearly correlated with body weight. After adjustment for weight, mean Fmvrel(m1LH) increases from the age of 3 to 6 yrs, then remains at 3.33 g (SD 0.31 g) between 6 and 19 yrs, independent of age and gender. The difference between legs decreases from 10% at 3 yrs to a constant 5.5% after the age of 7 yrs. Weight-adjusted MIGF also increases steeply from 3 to 6 yrs, then shows a further linear, less steep increase - in males through to age 19 yrs while females show a near-standstill after the age of 12 yrs. pKwb(m1LH) increases from the age of 7 yrs. CONCLUSION: This data from normal children from a healthy Caucasian population provide a reference for tests of motor function.