Is 40 kg grip strength in dominant hand considered weak after chronic hand injury done measurment was done by jamar instrument

What : What is your strength on the opposite side? 40kg is about 88 pounds. I know my own grip strength is about that and i wouldn't consider myself "weak" but I am also rather petite. I made it through orthopaedic training without ever breaking 100 pounds of grip strength. If you're occupation involves heavy gripping, this might be "weak" for you. Worker's compensation tends to perseverate on "objective" measures, such as jamar dynamometers, to establish levels of "disability" but they have little to do with clinical function. What's more important than the absolute number is how it compares to you non-dominant hand (it should be about 20% stronger) and how functional your hand is in your daily activities.

AS : As stated previously 40 kg is 88 lbs. The average males normative value for grip at age 30-39 is 105 lbs. That doesnt mean less than that is weak or abnormal. Normal va;ues are guidelines and reference points only and should not be used to establish good vs bad healing, good vs bad results or determine impairment ( and certainly have nothing to do with disability) certainly the perception of not beong or beong "normal" is important but the grip strength number from one or two tests is not an absolute number or an absolute indicator or result. As noted the opposite hand can be a good reference but know that the dominant hand may be 10 -15 % stronger and adjust expectations accordingly. Finally as noted before pain, hand size, method of testing, calibration of the tool, proper use of the tool and other variable afftect grip strength measurements. Also the type of chronic injury, ie was it a wrist injury, a bone injury, a nerve injury etc all influence what one might consider for stating what "weak" is.