Effect of Sand on Knee Load During a Single-Leg Jump Task: Implications for Injury Prevention and Rehabilitation Programs

The effect of surface on knee landing mechanics and muscle activity during a single-leg landing task in recreationally active females

OBJECTIVE

Investigate the effect of surface on frontal plane knee angle, knee moment and muscle activity.

DESIGN

Randomised cross over.

SETTING

University Laboratory.

METHODS

Twenty females performed single-leg hop-landings onto sand, grass and firm surfaces. Kinematic, kinetic and muscle activity data were obtained. Compatibility curves were used to visualise parameter estimates alongside P- values, and S-value transforms.

RESULTS

Knee angle for firm-sand (mean difference (d)‾ = -2.2°; 95% compatibility interval (CI): -4.6 to 0.28, p = 0.083, s = 3.6) and firm-grass (d‾ = -1.9; 95% CI: -4.3 to 0.5, p = 0.125, S = 3) yielded <4 bits of reputational information against the null hypothesis (H). 5 bits (p = 0.025) of information against H were observed for knee moment between firm-sand (d‾ = 0.17 N m/kg-1. m-1; 95% CI: 0.02 to 0.31) with similar effects for firm-grass (d‾ = 0.14 N m/kg-1. m-1; 95% CI: -0.02 to 0.29, p = 0.055, S = 4). Muscle activity across surfaces ranged from almost no (S = 1) reputational evidence against H (Quadriceps and Hamstrings) to 10-13 'bits' against H for lateral gastrocnemius (lower on sand).

CONCLUSIONS

Our study provides valuable information for practitioners of the observed effect sizes for lower-limb landing mechanics across surfaces in asymptomatic females.

The use of sand as an alternative surface for training, injury prevention and rehabilitation in English professional football and barriers to implementation: a cross-sectional survey of medical staff

PURPOSE

The purpose of the present study was to investigate the use of sand as an alternative surface for training, injury prevention and rehabilitation interventions in English professional football. A Secondary aim was to explore the potential barriers to implementation.

MATERIALS AND METHODS

All 92 teams from the male English professional football pyramid during the 2021-22 season were eligible to take part. A cross-sectional survey of the medical personnel (one per club) was conducted between June 2021 and December 2021 based on the RE-AIM framework. A total of 58 respondents (63% of all clubs) completed the survey.

RESULTS AND CONCLUSIONS

Only 18 (31%) of the clubs surveyed used sand-based interventions across the last 3 seasons. Respondents felt sand-based interventions would be effective at improving physiological gains (median 4, interquartile range [IQR] 4-5) and as part of injury prevention and rehabilitation strategies (4, IQR 3-4) but were indifferent in relation to its potential to improve sporting performance (3, IQR 3-4). Barriers to implementation of sand-based interventions within wider football were a lack of facilities, lack of awareness of its potential benefits, lack of high-quality evidence and the surface not being specific to the sport. Medical staff also did not perceive that coaches' positively viewed sand interventions as a training or injury management strategy.

Jumping on sand surfaces redistributes loading of the plantar surface to midfoot areas and reduces peak loading

The purpose was to assess plantar mechanical loading on different surface conditions when performing jumps. Twenty subjects performed standardized drop jumps and countermovement jumps both in shoes and barefoot on a rigid surface and barefoot on a sand surface. Flexible insoles of the Pedar Mobile system (PedarX, Novel GmbH) were used for data collection. The foot was subdivided into eight regions where peak pressures and relative loads were derived. Significant differences were found for several foot areas for both, countermovement and drop jumps. For the sand surface, as compared to the rigid surface, peak pressures were significantly reduced in the hallux&2nd toe, medial/lateral forefoot, and heel but were increased in the medial/lateral midfoot. The relative load shifted significantly from the forefoot to the midfoot area. Substantially different plantar pressure distribution patterns between conditions were observed in jumping. The switch from a rigid to a sand surface is associated with a lower mechanical loading, whereas switching back from sand to an indoor surface potentially increases this loading. Our results show that the observed pressure distribution patterns for different surfaces align with other tasks like playing soccer/running, are in a typical range for these sports and entail a comparable mechanical loading.

Drop Jumping on Sand Is Characterized by Lower Power, Higher Rate of Force Development and Larger Knee Joint Range of Motion

Plyometric training on sand is suggested to result in advanced performance in vertical jumping. However, limited information exists concerning the biomechanics of drop jumps (DJ) on sand. The purpose of the study was to compare the biomechanical parameters of DJs executed on rigid (RIGID) and sand (SAND) surface. Sixteen high level male beach-volleyball players executed DJ from 40 cm on RIGID and SAND. Force- and video-recordings were analyzed to extract the kinetic and kinematic parameters of the DJ. Results of paired-samples t-tests revealed that DJ on SAND had significantly (p < 0.05) lower jumping height, peak vertical ground reaction force, power, peak leg stiffness and peak ankle flexion angular velocity than RIGID. In addition, DJ on SAND was characterized by significantly (p < 0.05) larger rate of force development and knee joint flexion in the downward phase. No differences (p > 0.05) were observed for the temporal parameters. The compliance of SAND decreases the efficiency of the mechanisms involved in the optimization of DJ performance. Nevertheless, SAND comprises an exercise surface with less loading during the eccentric phase of the DJ, thus it can be considered as a surface that can offer injury prevention under demands for large energy expenditure.

Reliability and Repeatability of ACL Quick Check®: A Methodology for on Field Lower Limb Joint Kinematics and Kinetics Assessment in Sport Applications

Anterior cruciate ligament (ACL) lesion represents one of the most dramatic sport injuries. Even though clinical screenings aiming at identifying subjects at risk of injuries are gaining popularity, the use of sophisticated equipment still represents a barrier towards their widespread use. This study aimed to test both reliability and repeatability of a new methodology to assess lower limb joints kinematics and kinetics directly on field with the aid of video cameras and plantar pressure insoles. Ten athletes and one case study (post ACL surgery) were assessed in a gait laboratory, while performing double leg squats, through the simultaneous acquisition of stereophotogrammetry, force plates, commercial video cameras and plantar pressure insoles. Different sources of errors were investigated and both reliability and repeatability analysis performed. Minimum and maximum RMSE values of 0.74% (right knee joint center trajectory) and 64.51%, respectively (ankle dorsi-plantarflexion moment), were detected. Excellent to good correlation was found for the majority of the measures, even though very poor and inverse between-trials correlation was found on a restricted number of trials especially for the ankle dorsi-plantarflexion moment. These findings could be used in combination with already available screening tools in order to provide more repeatable results.

EFFECTS OF SURFACE ON TRIPLE HOP DISTANCE AND KINEMATICS

Background

The single leg triple hop (SLTH) test is often utilized by rehabilitation practitioners as a functional performance measure in a variety of patient groups. Accuracy and consistency are important when measuring the patient progress and recovery. Administering the SLTH test on different surfaces, consistent with the patient's sport, may affect the hop distances and movement biomechanics.

Purpose

The purpose of this study was to examine the effects of court and turf surfaces on the hop distance, limb symmetry index (LSI), and lower extremity kinematics of a SLTH test.

Methods

Recreationally active female participants (n=11, height 163.8 ± 7.1cm, mass 63.1 ± 7.1kg, age 18.9 ± 0.9yrs), without injury, volunteered to participate in the study. Three maximal effort SLTH test trials on two different surfaces (court, synthetic turf) were collected and analyzed using 3D motion analysis techniques. Outcome variables included SLTH test distances and LSI values and sagittal plane kinematics including trunk, hip, knee and ankle range of motion (ROM) during the last two landings of each SLTH test trial. The second landing involves an absorption phase and propulsion phase in contrast to the final landing which involves absorption and final balance on the single leg. Paired t-tests were used to determine differences between surfaces in hop distance and LSI values. Two-way repeated measures ANOVA were used to determine differences between surfaces in kinematic variables.

Results

The total SLTH test distance was not statistically different between the court (4.11 ± 0.47m) and turf (4.03 ± 0.42m, p=0.47) surfaces. LSI for the court surface was 100.8 ± 3.0% compared to 99.7 ± 3.0% for turf surface, which was not statistically different (p=0.30). Knee flexion ROM was significantly less (p=0.04) on the turf compared to the court surface during the second landing. Ankle flexion range of motion was also significantly less (p=0.03) during the second landing on turf compared to court.

Conclusions

Type of surface influenced landing kinematics but not total SLTH test distance. When evaluating the quality of landings during a SLTH test, it may be warranted to observe each type of landing and the type of surface used during single leg tests.

Level of Evidence

2.