Assessment of Lower Limb Muscle Strength and Power Using Hand-Held and Fixed Dynamometry: A Reliability and Validity Study.
BACKGROUND
Hand-held dynamometry (HHD) has never previously been used to examine isometric muscle power. Rate of force development (RFD) is often used for muscle power assessment, however no consensus currently exists on the most appropriate method of calculation. The aim of this study was to examine the reliability of different algorithms for RFD calculation and to examine the intra-rater, inter-rater, and inter-device reliability of HHD as well as the concurrent validity of HHD for the assessment of isometric lower limb muscle strength and power.


METHODS
30 healthy young adults (age: 23±5 yrs, male: 15) were assessed on two sessions. Isometric muscle strength and power were measured using peak force and RFD respectively using two HHDs (Lafayette Model-01165 and Hoggan microFET2) and a criterion-reference KinCom dynamometer. Statistical analysis of reliability and validity comprised intraclass correlation coefficients (ICC), Pearson correlations, concordance correlations, standard error of measurement, and minimal detectable change.


RESULTS
Comparison of RFD methods revealed that a peak 200 ms moving window algorithm provided optimal reliability results. Intra-rater, inter-rater, and inter-device reliability analysis of peak force and RFD revealed mostly good to excellent reliability (coefficients ≥ 0.70) for all muscle groups. Concurrent validity analysis showed moderate to excellent relationships between HHD and fixed dynamometry for the hip and knee (ICCs ≥ 0.70) for both peak force and RFD, with mostly poor to good results shown for the ankle muscles (ICCs = 0.31-0.79).


CONCLUSIONS
Hand-held dynamometry has good to excellent reliability and validity for most measures of isometric lower limb strength and power in a healthy population, particularly for proximal muscle groups. To aid implementation we have created freely available software to extract these variables from data stored on the Lafayette device. Future research should examine the reliability and validity of these variables in clinical populations.
School of Exercise Science, Faculty of Health Sciences, Australian Catholic University, Melbourne, Australia.
Benjamin F
BF
Mentiplay
School of Exercise Science, Faculty of Health Sciences, Australian Catholic University, Melbourne, Australia.
Luke G
LG
Perraton
School of Exercise Science, Faculty of Health Sciences, Australian Catholic University, Melbourne, Australia.
Kelly J
KJ
Bower
School of Allied Health, Faculty of Health Sciences, Australian Catholic University, Melbourne, Australia.
Brooke
B
Adair
Department of Physiotherapy, Singapore General Hospital, Singapore, Singapore.
Yong-Hao
YH
Pua
Department of Physiotherapy, Epworth Healthcare, Melbourne, Australia; School of Physiotherapy, Faculty of Medicine, Denistry and Health Sciences, The University of Melbourne, Melbourne, Australia.
Gavin P
GP
Williams
School of Exercise Science, Faculty of Health Sciences, Australian Catholic University, Melbourne, Australia.
Rebekah
R
McGaw
School of Exercise Science, Faculty of Health Sciences, Australian Catholic University, Melbourne, Australia.
Ross A
RA
Clark
D000293:Adolescent; D000328:Adult; D000465:Algorithms; D005260:Female; D006801:Humans; D007537:Isometric Contraction / Q000502:physiology; D035002:Lower Extremity / Q000502:physiology*; D008297:Male; D053580:Muscle Strength / Q000502:physiology*; D053581:Muscle Strength Dynamometer; D018482:Muscle, Skeletal / Q000502:physiology*; D015203:Reproducibility of Results; D012984:Software; D055815:Young Adult