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.
Key words
landing - knee - valgus - jumping - drop jump
