Different Modes of Feedback and Peak Vertical Ground Reaction Force During Jump Landing: A Systematic Review

Context:

Excessive ground reaction force when landing from a jump may result in lower extremity injuries. It is important to better understand how feedback can influence ground reaction force (GRF) and potentially reduce injury risk.

Objective:

To determine the effect of expert-provided (EP), self-analysis (SA), and combination EP and SA (combo) feedback on reducing peak vertical GRF during a jump-landing task.

Data Sources:

We searched the Web of Science database on July 1, 2011; using the search terms ground reaction force, landing biomechanics, and feedback elicited 731 initial hits.

Study Selection:

Of the 731 initial hits, our final analysis included 7 studies that incorporated 32 separate data comparisons.

Data Extraction:

Standardized effect sizes and 95% confidence intervals (CIs) were calculated between pretest and posttest scores for each feedback condition.

Data Synthesis:

We found a homogeneous beneficial effect for combo feedback, indicating a reduction in GRF with no CIs crossing zero. We also found a homogeneous beneficial effect for EP feedback, but the CIs from 4 of the 10 data comparisons crossed zero. The SA feedback showed strong, definitive effects when the intervention included a videotape SA, with no CIs crossing zero.

Conclusions:

Of the 7 studies reviewed, combo feedback seemed to produce the greatest decrease in peak vertical GRF during a jump-landing task.Key Words: injury prevention, knee, feedback, landing biomechanics

Key Points

• All modes of feedback effectively reduced ground reaction force during a jump-landing task.
• Combination feedback demonstrated the strongest effect sizes for reducing ground reaction force compared with expert-provided and self-analysis feedback.
• More high-quality studies are needed to support the use of feedback interventions for altering lower extremity landing forces and decreasing lower extremity injury risk.

Landing is an essential athletic task used during many different sporting activities, including basketball, volleyball, and gymnastics.^1–3 The act of jumping and landing during these different sporting activities involves different magnitudes of ground reaction forces (GRFs).⁴ The GRF magnitudes have been reported to be greatest during the landing phase of a jump when the knee is between 0° and 25° of flexion, a point at which the knee must resist a rapid change in kinetic energy.⁵ Excessive GRFs may result in lower extremity injuries.^3,6–8The knee is largely responsible for energy attenuation of the lower extremity when landing from a jump,^9,10 so this joint may have increased susceptibility to injury during such a task. Researchers have identified the presence of damage to the subchondral bone, cartilage, and soft tissue due to extreme forces imposed on the lower extremity during selected landing activities.¹¹ A positive moderate correlation between increased vertical GRF and increased anterior tibial acceleration when landing from a jump supports the hypothesis that individuals landing with greater impact loads could have an increased risk of anterior cruciate ligament (ACL) injury.¹² Given that the main function of the ACL is preventing anterior translation of the tibia, landing with increased GRF and thus increased anterior tibial acceleration may place more strain on the ligament, increasing the likelihood of ligament rupture.To reduce the risk of injury associated with increased GRF during landing, different interventions have been used to decrease GRF by altering lower extremity biomechanics during landing. To our knowledge, no researchers have evaluated whether reducing an individual''s GRF decreases his or her risk of injury, but compelling data have suggested that higher GRF and other factors may increase the risk of substantially injuring the knee.¹³ Specifically, prospective data have shown that GRF during a jump-landing task was 20% higher in female athletes who sustained an ACL rupture than in athletes who did not.¹³ These data spark a compelling but unsubstantiated theory that reducing high GRFs may coincide with a decreased risk of knee injury. Clinical trials to evaluate the true prophylactic capabilities of reducing GRF to limit knee injuries are likely expensive and logistically difficult to conduct. Therefore, successfully identifying an intervention that can manipulate GRF is important before these studies are performed.Various methods have been implemented to teach proper landing biomechanics to prevent future injury.¹⁴ For example, feedback is a modality used to prompt an individual to correct potentially harmful biomechanics and reduce high GRF. Feedback can be defined as sensory information made available to the participant during or after a task in an attempt to alter a movement.¹⁵ It can include information related to the sensations associated with the movement (eg, the feel or sound the participant experiences while performing the task) or related to the result of the action with respect to the environmental goal.¹⁵ Different modes of feedback have been reported and include (1) expert-provided (EP) feedback through oral correction,¹⁶ oral instruction,^17,18 or visual demonstration¹⁶; (2) self-analysis (SA) feedback conducted with videotape correction^19,20 or self-correction from previous trials¹⁷; and (3) combination (combo) feedback that uses both EP and SA feedback.^19,21 Through EP feedback, professionals can analyze movements and provide various forms of oral and visual feedback to alter that task, whereas SA feedback requires the participant to identify movement characteristics that need to be altered and to adjust to change that specific task.Recently, a surge of injury-prevention programs have been implemented to reduce the risk of ACL injury in athletes.^22,23 These programs often incorporate feedback techniques and aim to reduce the risk of injury by teaching athletes to land properly to reduce stress on the lower extremity and potentially prevent acute and chronic lower extremity injuries.¹⁹ Altering the landing phase of a jump via various feedback methods could result in decreased GRFs and increased flexion angles at the knee, which may decrease the risk of lower extremity injury.Although programs incorporating feedback are increasing in popularity, the magnitude of the effect that different types of feedback have on reducing GRF has not been evaluated systematically. Knowledge of the efficacy of feedback on reducing potentially harmful GRF may help clinicians determine whether feedback should be incorporated into jump-landing training programs. Therefore, the purpose of our study was to systematically evaluate the current literature to determine the magnitude of immediate and delayed effects of EP, SA, and combo feedback interventions on reducing peak vertical GRF during a jump-landing task in healthy individuals.