Patellar Tendon Force Differs Depending on Jump-Landing Tasks and Estimation Methods

Patellar tendinopathy is a chronic overuse injury of the patellar tendon which is prevalent in jump-landing activities. Sports activities can require jumping not only with a vertical component but also in a forward direction. It is yet unknown how jumping in the forward direction may affect patellar tendon forces. The main purpose of this study was to compare PTF between landings preceded by a vertical jump and a forward jump in volleyball players. The second purpose was to compare two different estimation methods of the patellar tendon force. Fifteen male volleyball players performed vertical and forward jump-landing tasks at a controlled jump height, while kinetics and kinematics were recorded. Patellar tendon forces were calculated through two estimation methods based on inverse dynamic and static optimization procedures, using a musculoskeletal model. Results showed that forward jump-landing generated higher patellar tendon forces compared to vertical jump-landing for both estimation methods. Surprisingly, although the static optimization method considered muscle co-contraction, the inverse kinematic method provided statistically significant higher patellar tendon force values. These findings highlight that limiting the forward velocity component of the aerial phase appears to reduce the load on the patellar tendon during landing and may help to prevent patellar tendinopathy.

Electromyographic Determination of Jump Landing Sequence and Pre-activation Times During One-foot Landing

Introduction: Monopodal jumping is a common gesture in daily life and sports. In the Landing Phase (LF), potential energy is absorbed from the tridimensional stability of the Lower Limb (LH). This stability depends on neuromuscular strategies that include factors such as Muscle Preactivation Times (MAT) and the Sequence of Participation (SP) of the muscle groups. The alteration of TPA has been pointed out as a factor of possible injury. The aim of this study was to determine the preactivation times and participation sequence of the gluteus medius, adductor magnus, rectus femoris, vastus medialis quadriceps, biceps femoris longus, semimembranosus and soleus muscles during the monopodal jump landing in university students. At the same time, we sought to determine the existence or not of significant differences between men and women. Materials and methods: Twenty-six young adults, 16 women and 10 men, participated. An inertial sensor and 7 surface electrodes were used to collect electromyographic data in the gluteus medius, rectus femoris and vastus medialis quadriceps, semimembranosus, biceps femoris long head, soleus and adductor magnus muscles. Results: The general activation sequence was Vastus medialis -Biceps femoris longus - Adductor magnus - Gluteus medius - Rectus femoris -Semimembranosus and soleus. The data obtained reflects the activation prior to ground contact of all the muscles studied. There were differences between genders. Women presented a previous activation in all muscles with the exception of the gluteus medius. The muscles with the greatest variability were the adductor magnus in men and the rectus femoris in women. Conclusion: The significant differences found between men and women show that there are trends that can be the beginning to better understand the risk factors for injury generation. The TPA data presented a great variability which could reflect the existence of different activation patterns and not a unique behavior of the MMII musculature.

Examining the Relationship Between a Neuromuscular Control Baseline Battery for Sport-Related Concussion and Anterior Cruciate Ligament Injury Risk

ObjectiveTo examine the relationship between the m-CTSIB and Landing Error Scoring System in a sample of collegiate female athletes.BackgroundRecent literature has linked concussion and neuromuscular deficits in the lower extremity after injury. Neuromuscular control is frequently assessed using balance measures for concussion, but also dynamically to identify anterior cruciate ligament injury (ACL) risk via jump-landing movement screening.Design/MethodsThirty-nine healthy, collegiate female soccer (n = 22) and volleyball (n = 17) athletes completed the modified-Clinical Test of Sensory Interaction of Balance (m-CTSIB) and the Landing Error Scoring System (LESS). Measures consisted of total m-CTSIB sway index scores on individual conditions (firm surface eyes open [condition 1] and eyes closed [2], foam surface eyes open [3] and eyes closed [4]), m-CTSIB overall score, and total LESS errors. LESS scores were also categorized into a low (0–4 errors) and high (5 + errors) risk to determine if athletes with worse neuromuscular control on the LESS has worse balance on the m-CTSIB. A Spearman's rank-order correlation was conducted to determine the strength of the relationship between LESS and m-CTSIB performance. A series of Mann-Whitney U test were performed to determine differences between low and high LESS performance on m-CTSIB performance.ResultsThere was a weak, negative correlation between LESS and m-CTSIB performance (rs(37) = −0.153, p = 0.35). Further, there were no differences between the low and high risk LESS groups on sway index scores on conditions 1 (U = 158.5, p = 0.39), 2 (U = 156.0, p = 0.36), 3 (U = 165.5, p = 0.51), or 4 (U = 128.5, p = 0.08), as well as overall m-CTSIB scores (U = 150.5, p = 0.28).ConclusionsThere appears to be a lack of relationship between the LESS and m-CTSIB tests, revealing the independence of static and dynamic lower extremity neuromuscular function. Athletes who may be more at risk for ACL injury due to abnormal jump-landing biomechanics, do not differ from low-risk athletes on baseline balance assessment.

Effect of Strength Training on Jump-Landing Biomechanics in Adolescent Females

Background: Sex-based differences in neuromuscular characteristics relevant to anterior cruciate ligament (ACL) injury risk may arise as compensation for divergent strength development during puberty. Strength training during this period may prevent the development of these undesirable neuromuscular characteristics. Hypothesis: Strength-trained middle school girls will have improved jump-landing biomechanics compared with control participants. Study Design: Cohort study. Level of Evidence: Level 3. Methods: Maximum voluntary isometric contraction in hip extension and abduction and knee extension and flexion as well as Landing Error Scoring System (LESS) scores were collected for healthy female middle school students of grades 6 to 8. Strength-training participants (STR: N = 30; height, 1.63 ± 0.07 m; mass, 48.1 ± 7.6 kg; age, 12.5 ± 1.0 y) were matched with control participants (CON: N = 30; height, 1.60 ± 0.09 m; mass, 47.2 ± 8.9 kg; age, 12.6 ± 0.9 y). The training consisted of a 6-month strength-training program administered through a gym class curriculum that targeted the lower extremity. A repeated-measures mixed-model analysis of variance was used for comparisons between groups and across time (α = 0.05). Stepwise linear regression was used to examine the relationship between strength change and LESS score change. Results: Strength values (N·m/kg) increased across time and to a greater degree in STR for hip extension (baseline 3.98 ± 1.15 vs follow-up 4.77 ± 1.80), hip abduction (4.22 ± 1.09 vs 5.13 ± 2.55), and knee flexion (3.27 ± 0.62 vs 3.64 ± 1.40) compared with CON. LESS grades significantly decreased across time in STR (5.58 ± 1.21 vs 4.86 ± 1.44) and were significantly lower than CON (5.98 ± 1.42) at follow-up ( P < 0.001). The change in hip extension and knee extension strength explained 67% of the variance ( P < 0.001) in the LESS change score in the STR group. Conclusion: A school-based strength-training program that focused on hip and knee musculature significantly improved jump-landing biomechanics (as determined by LESS) relevant to ACL injury risk. Further investigation using different strength-training approaches in this age group is warranted. Clinical Relevance: Strength training during adolescence holds promise as an injury prevention program. The use of a school-based approach is novel and may represent a robust opportunity for injury prevention programs, as physical education class is often mandatory in this age group.