PMID- 28714767
OWN - NLM
STAT- MEDLINE
DCOM- 20180405
LR  - 20180405
IS  - 1555-0273 (Electronic)
IS  - 1555-0265 (Linking)
VI  - 13
IP  - 3
DP  - 2018 Mar 1
TI  - Comparison of Methods of Calculating Dynamic Strength Index.
PG  - 320-325
LID - 10.1123/ijspp.2017-0255 [doi]
AB  - PURPOSE: To determine the reliability and variability of the Dynamic Strength 
      Index (DSI) calculated from squat-jump (SJ) vs countermovement-jump (CMJ) peak 
      force (PF) and to compare DSI values between methods. METHODS: Male youth soccer 
      and rugby league players (N = 27; age 17.2 +/- 0.7 y, height 173.9 +/- 5.7 cm, body 
      mass 71.1 +/- 7.2 kg) performed 3 trials of the SJ, CMJ, and isometric midthigh 
      pull (IMTP) on 2 separate days. DSI was calculated by dividing the PF during each 
      jump by the IMTP PF. RESULTS: DSI-SJ exhibited moderate (intraclass correlation 
      coefficient [ICC] = .419) within-session reliability and high variability 
      (percentage coefficient of variation [%CV] = 15.91) during session 1; however, 
      this improved noticeably during session 2 (ICC = .948, %CV = 4.03). In contrast, 
      DSI-CMJ showed nearly perfect within-session reliability (ICC = .920-.952) and 
      low variability (%CV = 3.80-4.57) for both sessions. Moreover, DSI-SJ values 
      demonstrated a small yet significant increase between sessions (P = .01, 
      d = 0.37), whereas only a trivial and nonsignificant increase was observed for 
      DSI-CMJ between sessions (P = .796, d = 0.07). Between-sessions reliability was 
      very high for the DSI-SJ (ICC = .741) and nearly perfect for the DSI-CMJ 
      (ICC = .924). There was no significant or meaningful difference (P = .261, 
      d = 0.12) between DSI-SJ (0.82 +/- 0.18) and DSI-CMJ (0.84 +/- 0.15). CONCLUSIONS: 
      Practitioners should use DSI-CMJ, as it is a more reliable measure than DSI-SJ, 
      although it produces similar ratios.
FAU - Comfort, Paul
AU  - Comfort P
FAU - Thomas, Christopher
AU  - Thomas C
FAU - Dos'Santos, Thomas
AU  - Dos'Santos T
FAU - Jones, Paul A
AU  - Jones PA
FAU - Suchomel, Timothy J
AU  - Suchomel TJ
FAU - McMahon, John J
AU  - McMahon JJ
LA  - eng
PT  - Comparative Study
PT  - Journal Article
DEP - 20180307
PL  - United States
TA  - Int J Sports Physiol Perform
JT  - International journal of sports physiology and performance
JID - 101276430
SB  - IM
MH  - Adolescent
MH  - Athletes
MH  - Athletic Performance
MH  - Exercise Test/*standards
MH  - Football
MH  - Humans
MH  - Male
MH  - *Muscle Strength
MH  - Reproducibility of Results
MH  - Soccer
OTO - NOTNLM
OT  - isometric force
OT  - jump performance
OT  - strength assessment
EDAT- 2017/07/18 06:00
MHDA- 2018/04/06 06:00
CRDT- 2017/07/18 06:00
PHST- 2017/07/18 06:00 [pubmed]
PHST- 2018/04/06 06:00 [medline]
PHST- 2017/07/18 06:00 [entrez]
AID - 10.1123/ijspp.2017-0255 [doi]
PST - ppublish
SO  - Int J Sports Physiol Perform. 2018 Mar 1;13(3):320-325. doi: 
      10.1123/ijspp.2017-0255. Epub 2018 Mar 7.