Muscle strength refers to the ability of the muscles to produce maximal force. One assessment method is to measure handgrip strength, which involves the maximal isometric force of the finger flexors using a handheld device. Handgrip strength is a convenient, reliable, valid and safe measure that is an important indicator of general health and sports performance. For example, low adult handgrip strength is associated with an increased risk of early death from all-causes and cause-specific chronic conditions such as heart disease. It is also associated with performance in sports requiring gripping and force application like hockey, weightlifting and wrestling. These reasons help explain why handgrip strength is widely used in clinical, health/fitness and sport settings, as well as for population health surveillance.
Using handgrip strength to accurately measure muscle strength is an important challenge for sports medicine and exercise science professionals. This is because handgrip strength is strongly associated with body size, suggesting that handgrip strength should be corrected (or normalized) for differences in body size to obtain a more sensitive measure of muscle strength. Various normalizing methods have been used, with handgrip strength often divided by body mass or body mass index. In our study, published in the January 2022 edition of Medicine & Science in Sports & Exercise®, we examined the optimal way to normalize adult handgrip strength for differences in body size.
We used a nationally representative sample of 8,690 American adults aged 20 years and older from the National Health and Nutrition Examination Survey (NHANES). Handgrip strength was measured using handheld dynamometry, with body size measured as body mass, height and waist circumference. The most appropriate dimensions associated with handgrip strength were identified using allometry. We found that neither body mass nor body mass index were appropriate, and that height was the best single measure of body size associated with handgrip strength. As a result, we recommend that handgrip strength be divided by height2 to best normalize handgrip strength. We also developed normative-referenced centile values for handgrip strength normalized using height2.
Normalizing handgrip strength to height2 not only helps to create a level playing field for population-based research, but also provides a simple way to compare the handgrip strength of people who differ in body size. Our normative values can also be used by sports medicine and exercise science professionals to determine a person’s percentile rank in comparison with the U.S. adult population. Further, because inferior normalizing approaches have generally been used, researchers should examine whether normalizing handgrip strength to height2 impacts the associations between handgrip strength and health or sports performance.
Grant R. Tomkinson, PhD, is a professor in the Department of Education, Health and Behavior Studies at the University of North Dakota. His research mainly focusses on the assessment and interpretation of physical fitness. Dr. Tomkinson is an ACSM member.
Alan M. Nevill, PhD, is the research professor in the Faculty of Education Health and Wellbeing at the University of Wolverhampton in the United Kingdom. His specialization is in biostatistics applied to health, sport and exercise sciences. His most recent research focusses on multilevel and allometric modelling of large data sets, analyzing human health and performance associated with body size.
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