Change Recommended In Assessment of Drop Vertical Jump
Key findings
- In a study of 44 female adolescent athletes who were evaluated with the drop vertical jump (DVJ) activity, neuromuscular control during the second landing was significantly poorer than during the first landing
- In the overall cohort and in softball players, there was significantly greater between-participant variability in neuromuscular control for the second landing than for the first landing
- Gymnasts did not demonstrate significant intraparticipant variability in that regard, probably because of the type of landing training they receive
- Scoring both the first and second landings during the DVJ activity could more comprehensively assess an athlete's neuromuscular control
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Neuromuscular control in athletes has a central role in their risk of lower extremity injuries, especially knee injuries, and their ability to recover. Body alignment during landing activities is particularly important because many noncontact injuries, such as anterior cruciate ligament (ACL) tears, occur with poor limb alignment during jumping, landing or pivoting.
A popular method of documenting lower extremity neuromuscular control is the drop vertical jump (DVJ) activity. This two-part test requires participants to drop from the edge of a 31-cm box, directly onto the ground below, then immediately jump as high as possible before landing on the ground for a second time.
Current interest in the DVJ focuses on the first landing. However, the second landing, which does not require conscious mental or motor planning, may be more representative of typical landings under various sporting conditions.
In Sports Health, Sports Medicine Orthopaedic Surgeon Luke S. Oh, MD, in the Department of Orthopaedics at Massachusetts General Hospital, presents evidence that the second landing in the DVJ provides additional insight into an athlete's motor control.
Study Participants
The researchers recruited 44 female high school and college athletes—13 gymnasts and 31 softball players (average age 16)—who were training at competitive facilities and had not been injured within the past three months. Most studies of neuromuscular control in women have focused on soccer or basketball players, but gymnasts have a high incidence of ACL tears, and softball players are at high risk of knee injuries.
Study Design
After a practice trial, the athletes performed the DVJ activity three times while a two-dimensional video was made. Their biomechanics were evaluated with the Landing Error Scoring System (LESS), which calls for the assessment of 17 items: 11 measures of the position of the lower limbs at initial contact with the ground and six measures of joint positions at maximum displacement, and the overall quality of the landings.
The average of the three LESS scores was used as the representative score for each athlete.
Differences Between First and Second Landings
- Across all 44 participants, the average LESS score for the second landing was significantly greater (indicating poorer neuromuscular control) than the average score for the first landing. Overall, there was a 45% increase in LESS score at the second landing (P < .01)
- Subgroup analysis of softball players and gymnasts supported the main finding: in both groups of athletes, the average LESS score for the second landing was significantly greater than that for the first landing
- The poorer scores for the second landing were due to decreased knee, hip and trunk flexion—landing mechanics that especially predispose athletes to injury
Variability Between Softball Players and Gymnasts
The researchers had hypothesized that there would be greater between-participant variability in LESS scores for the second landing than for the first landing. That proved to be true of the entire cohort and the subgroup of softball players.
However, among gymnasts, there was no significant difference in the variations between the three trials of the first landing compared with the second.
This difference between softball players and gymnasts in this regard is probably attributable to the training they receive:
- Gymnasts are trained to land with upright posture and decreased hip and knee flexion so that the lower extremities are straight and close together. This is noteworthy because decreased hip and knee flexion at impact is biomechanically unfavorable and increases ground reaction forces at landing
- Softball players rarely receive landing training, but that might create problems of its own. During the second landing, they exhibited significantly decreased values for hip flexion angle and trunk flexion angle
Scoring both the first and second landings during the DVJ activity seems to provide a more comprehensive view of an athlete's neuromuscular control than assessing the first landing alone.
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