Description

The preoperative grip strength of a person can be measured using a dynamometer. If the grip strength is below the recommended cut-off level for age and sex, then the person (1) is at high risk for post-operative complications and (2) should have nutritional assessment. The cut-off value was set at 85% of that shown by normal persons of that age and gender. The hand grip strength predicted 74% of complications.

Patient selection: 247 normal volunteers used to derive normal values for age and gender with ages from 16 to 95

Measurement:

(1) Performed using a mechanical dynamometer.

(2) Results reported in kilograms.

(3) The nondominant hand tends to show slightly great strength (Table III, page 21, Webb (1989).

Criteria for serious complication:

(1) post-operative stay > 14 days

(2) death

Quadratic Equations for Normal Grip Strength

female grip strength in kilograms =

= 25.9 + (0.55 * (age in years)) - (0.0077 * ((age in years)^2))

R value: 0.78

male grip strength in kilograms =

= 42.03 + (0.57 * (age in years)) - (0.0073 * ((age in years)^2))

R value: 0.56

from Table II, page 31, Webb et al (1989)

cut-off strength in kilograms =

= (grip strength in kilograms for gender and age) * 0.85

Exponential Equations for Normal Grip Strength

female grip strength in kilograms =

= 3.91 * EXP(-0.012 * (age in years))

R value: 0.74

male grip strength in kilograms =

= 4.12 * EXP(-0.0049 * (age in years))

R value: 0.48

from Table II, page 31, Webb et al (1989)

NOTE: When age values are entered into the exponential equations, unrealistic values are returned. I tried several variations of the equations and could not get reliable results.

Age and Gender Grip Strength Cutoff Values (at 85% of Normal)

 age in years female grip strength in kilograms male grip strength in kilograms 15 28 42 20 29 43 25 30 44 30 30 45 35 30 45 40 30 45 45 30 45 50 29 45 55 28 44 60 27 43 65 25 41 70 23 39 75 20 37 80 18 35 85 15 32 90 11 29 95 8 26

from Table V, page 32, Webb et al (1989)

Medal Equations for Grip Strength Cutoff Values

from Figure 3, page 32, Webb et al (1989)

female age 15-30 years grip strength in kilograms =

= (-0.01 * ((age in years)^2)) + (0.65 * (age in years)) + 20

female age 30-95 years grip strength in kilograms =

= (-0.00483 * ((age in years)^2)) + (0.25193 * (age in years)) + 27.3632

male age 15-40 years grip strength in kilograms =

= (-0.00752 * ((age in years)^2)) + (0.5805 * (age in years)) + 34.025

male age 40-95 years grip strength in kilograms =

= (-0.004453 * ((age in years)^2)) + (0.2498268 * (age in years)) + 42.665