Articles
PLoS ONE (19326203)20(5 May)
Knee and ankle injuries are the most common injuries in handball players. Many of these injuries occur toward the end of the game when fatigue sets in. The underlying mechanisms of this phenomenon are not well understood. This study investigated the effect of a handball match-simulation protocol on the hamstring-to-quadriceps (H:Q) and evertor-to-invertor (E:I) peak torque ratios. Thirty professional male handball players from Iranian super league teams participated in this study. Isokinetic concentric peak torque of the hamstrings, quadriceps, ankle invertor, and ankle evertors were measured at angular velocities of 60, 120, and 180 deg/s before and after the simulated handball match-induced fatigue protocol using a Biodex Isokinetic Dynamometer. Peak torque ratio of H:Q and E:I were calculated and compared between pre- and post-fatigue conditions. Fatigue significantly reduced H:Q peak torque ratio at 60 (p=0.049), 120 (p=0.002) and 180 (p=0.014) deg/s, as well as E:I peak torque ratio at 60 (p=0.010), 120 (p=0.003) and 180 (p=0.003) deg/s. These changes could contribute to an increased risk of anterior cruciate ligament (ACL) tears and lateral ankle sprains. Given the greater reduction in the H:Q peak torque ratio in hamstring muscles, targeted strengthening and improving the endurance of these muscles is recommended for professional handball players to mitigate fatigue effects. © 2025 Dastjerdi et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Shahbazi, M.,
Hamed, E.,
Salari-esker, F.,
Bashiri, B.,
Khezri, D. Knee (18735800)52pp. 1-8
Background: Individuals with a history of anterior cruciate ligament reconstruction (ACLR) represent altered knee joint mechanics in running. Hip joint can make subtle compensations in response to ACLR. Effects of ACLR on hip joint compensatory mechanisms is not well known. The aim of this study was to evaluate the hip join mechanics and asymmetry in individuals with ACLR history. We hypothesized that ACLR individuals’ hip exhibit altered mechanics which can increase the risk of hip overuse or osteoarthritis. Methods: Kinetic and kinematic data of 20 males with ACLR history and 20 healthy males were collected bilaterally while running at 3.3 m·s−1. Hip and knee joints peak angles, peak moments, peak negative and positive power and negative and positive work in the sagittal plane were calculated. Also, asymmetry of the outcomes was calculated. A mixed design MANOVA was used to detect between-group and within-group (side-by-group interaction) effects of ACLR on outcomes. Results: Involved knee showed smaller flexion angle and negative work compared to uninvolved and control knee. In the hip joint, involved leg showed a higher flexion angle, extension moment, and peak positive and negative power as well as negative and positive work compared to uninvolved and control leg. ACLR group showed greater asymmetries in knee flexion angle, knee flexion moment, hip flexion angle, hip extension angle and hip negative power compared to healthy group. Conclusion: Hip and knee joints mechanics of involved and uninvolved sides of the ACLR individuals are different. These results show that ACLR affects hip joint as well as knee joint. When returning to activity and sport, mechanics of the hip joint as well as knee joint, must be considered in ACLR individuals. © 2024 Elsevier B.V.
Knee Surgery, Sports Traumatology, Arthroscopy (09422056)33(3)pp. 878-887
Purpose: The ability of current return-to-sport (RTS) tests to predict second anterior cruciate ligament (ACL) injuries (ACLI) in athletes with a history of ACL reconstruction (ACLR) is unclear. This study aimed to prospectively assess the risk of a second ACLI by identifying the most significant deviation in hop test results in professional athletes after ACLR compared to healthy peers. Methods: A total of 30 professional athletes with a history of ACLR and 30 healthy professional athletes participated in this study. Participants performed 10 functional hop tests, and the subsequent limb symmetry index (LSI) was compared between the groups. After a 3-year follow-up, the re-injury rate was assessed among the ACLR group. Fourteen ACLR athletes who sustained a second ACLI were included and matched with 14 controls from the healthy group. The LSI and the hop distance to body height percentage (D/H) were compared between the groups. Results: Statistical analyses confirmed a significant decrease in LSI in the ACLR group compared to the healthy group in the triple hop for distance (p =.023). In re-injured ACLR athletes, seven different hop tests showed a significant decrease in the D/H index compared to the healthy controls. Meanwhile, for LSI, only the triple cross-over hop for distance (p =.045) showed a significant increase in the healthy group. Conclusion: Before clearing athletes for RTS, assessing functional hop test results using the hop distance to body height ratio, aligned with normative data from healthy controls, could further enhance the prediction of reduced graft rupture risk. Level of Evidence: Level I. © 2024 European Society of Sports Traumatology, Knee Surgery and Arthroscopy.
Ghahderijani, F.R.,
Hamed, E.,
Salari-esker, F.,
Bashiri, B. Journal of Biomechanics (18732380)185
Running is generally considered a symmetrical activity that involves harmonized functions of upper and lower limbs. However, asymmetry can occur under certain conditions, such as fatigue, as lower limbs perform distinct functional tasks. While running, trunk muscles play a crucial role in transmitting loads between the upper and lower limbs, yet the impact of trunk muscle fatigue on the dominant and nondominant legs has not been well addressed. This study investigated the effects of trunk muscle fatigue on ground reaction force characteristics on dominant and nondominant legs in novice runners. Thirty participants were asked to run along a runway at 3.3 m · s−1 before and after a trunk muscle fatigue protocol. Ground reaction force data were collected bilaterally, and subsequent asymmetries were calculated. Trunk muscle fatigue had different effects on the dominant and nondominant legs. In the dominant leg peak medial force increased, while the nondominant leg showed reduced peak lateral force, peak braking force and peak negative free moment and increased medio-lateral impulse. Trunk muscle fatigue increased asymmetries in peak lateral force, peak braking force and decreased asymmetry in peak negative free moment. These findings suggest that trunk muscle fatigue, due to its different effects on dominant and nondominant legs, deteriorates running asymmetry and may increase injury risk in novice runners. Strengthening and improving the endurance of trunk muscles is recommended for novice runners to prevent strength reduction-related changes in running mechanics and mitigate injury risk. © 2025 Elsevier Ltd
Iranpour, A.R.,
Hemmatinafar, M.,
Nemati, J.,
Salesi, M.,
Hamed, E.,
Imanian, B. PLoS ONE (19326203)20(2 February)
Background The principle of gradual overload is crucial in improving sports performance, yet the effects of combining speed and weight overloads in plyometric training remain understudied. Objective This study investigated the effects of plyometric training with speed and weight overloads on isokinetic strength, explosive power, and agility in volleyball players. Method Forty male volleyball players were randomly assigned to four groups: plyometric training (PT), plyometric training with speed overload (PTS), plyometric training with weight overload (PTW), and plyometric training with both speed and weight overload (PTSW). Each group completed a four-week plyometric training regimen. Performance metrics, including Sarjent’s jump height (SJH), Spike jump height (SPJH), Sheppard test (ShT), muscle voluntary isometric contraction (MVIC), rate of force development (RFD), absolute peak torque (PTQ), relative peak torque (RPT), and average power (AP) of knee extensors and flexors were measured before and after the intervention. Results SJH improved significantly in PTS (P = 0.012), PTW (P = 0.041), and PTSW (P = 0.001) compared to PT. SPJH showed substantial gains in PTS (P = 0.002), PTW (P = 0.001), and PTSW (P = 0.001) compared to PT. Average jump height and highest jump in ShT were also significantly higher in PTS, PTW, and PTSW (P < 0.05). Additionally, RFDext240/s was enhanced considerably in PTS (P = 0.001) and PTSW (P = 0.001). Conclusion Based on the results, plyometric training with speed and weight overloads (PTSW) demonstrated superior enhancements in isokinetic strength, explosive power, and jumping performance. This combined approach is highly effective and significantly benefits male volleyball players, aiming to enhance their physical abilities. © 2025 Iranpour et al.
