Assessment of maximal handgrip strength: how many attempts are needed?
BACKGROUND
Handgrip strength (HGS) is used to identify individuals with low muscle strength (dynapenia). The influence of the number of attempts on maximal HGS is not yet known and may differ depending on age and health status. This study aimed to assess how many attempts of HGS are required to obtain maximal HGS.


METHODS
Three cohorts (939 individuals) differing in age and health status were included. HGS was assessed three times and explored as continuous and dichotomous variable. Paired t-test, intraclass correlation coefficients (ICC) and Bland-Altman analysis were used to test reproducibility of HGS. The number of individuals with misclassified dynapenia at attempts 1 and 2 with respect to attempt 3 were assessed.


RESULTS
Results showed the same pattern in all three cohorts. Maximal HGS at attempts 1 and 2 was higher than at attempt 3 on population level (P < 0.001 for all three cohorts). ICC values between all attempts were above 0.8, indicating moderate to high reproducibility. Bland-Altman analysis showed that 41.0 to 58.9% of individuals had the highest HGS at attempt 2 and 12.4 to 37.2% at attempt 3. The percentage of individuals with a maximal HGS above the gender-specific cut-off value at attempt 3 compared with attempts 1 and 2 ranged from 0 to 50.0%, with a higher percentage of misclassification in middle-aged and older populations.


CONCLUSIONS
Maximal HGS is dependent on the number of attempts, independent of age and health status. To assess maximal HGS, at least three attempts are needed if HGS is considered to be a continuous variable. If HGS is considered as a discrete variable to assess dynapenia, two attempts are sufficient to assess dynapenia in younger populations. Misclassification should be taken into account in middle-aged and older populations.
Department of Internal Medicine, Section of Gerontology and Geriatrics, VU University Medical Center, 1007 MB, Amsterdam, The Netherlands.
Esmee M
EM
Reijnierse
Department of Internal Medicine, Section of Gerontology and Geriatrics, VU University Medical Center, 1007 MB, Amsterdam, The Netherlands.
Nynke
N
de Jong
Department of Internal Medicine, Section of Gerontology and Geriatrics, VU University Medical Center, 1007 MB, Amsterdam, The Netherlands.|Department of Internal Medicine, Amstelland Hospital, 1180 AH, Amstelveen, The Netherlands.
Marijke C
MC
Trappenburg
Department of Gerontology and Geriatrics, Leiden University Medical Center, 2300 RC, Leiden, The Netherlands.|Department of Geriatrics, Bronovo Hospital, 2509 JH, The Hague, The Netherlands.
Gerard Jan
GJ
Blauw
UPMC UM 76, INSERM U 974, CNRS 7215, Institut de Myologie, 75651, Paris, France.
Gillian
G
Butler-Browne
Institute of Sport Sciences and Physiotherapy, University of Tartu, 51014, Tartu, Estonia.
Helena
H
Gapeyeva
UPMC UM 76, INSERM U 974, CNRS 7215, Institut de Myologie, 75651, Paris, France.
Jean-Yves
JY
Hogrel
School of Healthcare Science, John Dalton Building, Manchester Metropolitan University, M1 5GD, Manchester, UK.
Jamie S
JS
McPhee
Division of Medical Sciences and Graduate Entry Medicine, MRC-ARUK Centre of Excellence for Musculoskeletal Ageing Research, University of Nottingham, Royal Derby Hospital Centre, Uttoxeter Rd, Derby, DE22 3DT, UK.
Marco V
MV
Narici
Gerontology Research Centre and Department of Health Sciences, University of Jyväskylä, FI-40014, Jyväskylä, Finland.
Sarianna
S
Sipilä
Department of Biology of Physical Activity, University of Jyväskylä, FI-40014, Jyväskylä, Finland.
Lauri
L
Stenroth
McRoberts BV, Raamweg 43, 2596 HN, The Hague, The Netherlands.|Department of Human Movement Sciences, MOVE Research Institute Amsterdam, Vrije Universiteit, Van der Boechorststraat 7 1081 BT, Amsterdam, The Netherlands.
Rob C
RC
van Lummel
McRoberts BV, Raamweg 43, 2596 HN, The Hague, The Netherlands.
Mirjam
M
Pijnappels
Department of Rehabilitation Medicine, VU University Medical Center, 1007 MB, Amsterdam, The Netherlands.
Carel G M
CGM
Meskers
Department of Human Movement Sciences, MOVE Research Institute Amsterdam, Vrije Universiteit, Van der Boechorststraat 7 1081 BT, Amsterdam, The Netherlands.|Department of Medicine and Aged Care, The Royal Melbourne Hospital, The University of Melbourne, Parkville, Victoria 3052, Australia.
Andrea B
AB
Maier
D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D015331:Cohort Studies; D003430:Cross-Sectional Studies; D015577:Geriatric Assessment; D018737:Hand Strength; D006304:Health Status; D006801:Humans; D008875:Middle Aged; D053580:Muscle Strength; D015203:Reproducibility of Results; D055815:Young Adult
Aged; Geriatric assessment; Muscle strength; Reproducibility of Results; Sarcopenia