Sports Medicine International Open 2018; 02(02): E35-E40
DOI: 10.1055/a-0608-4280
Orthopedics & Biomechanics
© Georg Thieme Verlag KG Stuttgart · New York

Landing Styles Influences Reactive Strength Index without Increasing Risk for Injury

Dana Guy-Cherry
1  Texas Woman’s University, School of Physical Therapy, Houston, United States
,
Ahmad Alanazi
2  Majmaah University, Physical Therapy, Al Majma’ah, Saudi Arabia
,
Lauren Miller
1  Texas Woman’s University, School of Physical Therapy, Houston, United States
,
Darrin Staloch
1  Texas Woman’s University, School of Physical Therapy, Houston, United States
,
Alexis Ortiz-Rodriguez
3  UT Health San Antonio, Department of Physical Therapy, San Antonio, United States
› Author Affiliations
Further Information

Publication History

received 13 December 2017
revised  28 March 2018

accepted 05 April 2018

Publication Date:
22 May 2018 (online)

Abstract

The aim was to determine which three landing styles – stiff (ST), self-selected (SS), or soft (SF) – exhibit safer landing mechanics and greater jumping performance. Thirty participants (age: 26.5±5.1 years; height: 171.0±8.8 cm; weight: 69.7±10.1 kg) performed five trials of three randomized drop jump (40 cm) landing styles including SF (~60° knee flexion), ST (knees as straight as possible), and SS. Knee flexion and valgus angles and kinetics were measured. An electromyography system measured muscle activity of the gluteus maximus, quadriceps, hamstrings, tibialis anterior, and gastrocnemius. Reactive strength index (RSI) was used to measure jumping performance. ANOVAs were used to compare the three landings. All landings differed in knee flexion (p<0.001; effect size (η2): 0.9) but not valgus (p=.13; η2:.15). RSI (mm·ms-1) showed differences for all jumps (p<0.001; η2: 0.7) with SS (0.96) showing the highest value, then ST (0.93), and SF (0.64). Ground reaction forces were different between jumps (p<0.001; η2: 0.4) with SF (1.34/bodyweight (bw)) showing lower forces, then SS (1.50/bw), and ST (1.81/bw). No between-jump differences were observed for EMG (p>0.66; η2: 0.3). No landing demonstrated valgus landing mechanics. The SS landing exhibited the highest RSI. However, the 1.8/bw exhibited by the ST landing might contribute to overload of musculotendinous structures at the knee.