strength in both limbs throughout the course of rehabilitation after ACLR. 14 , 15 The purpose of the current study was to evaluate the change in involved and uninvolved quadriceps and hamstring strength, as well as limb symmetry indices (LSI), in regular intervals over the first 6 months following ACLR
Gulcan Harput, Volga B. Tunay and Matthew P. Ithurburn
Justin W.Y. Lee, Ming-Jing Cai, Patrick S.H. Yung and Kai-Ming Chan
significantly reduced the incidence of new and recurrent HSI among elite and amateur soccer players. 7 , 8 Routine testing of the eccentric hamstring strength for players before, during the competitive season, and during the rehabilitation may be a useful method to track the changes in hamstring strength
Benjamin Drury, Thomas Green, Rodrigo Ramirez-Campillo and Jason Moran
hamstring strength via performing the Nordic hamstring exercise (NHE). Its inclusion as an injury prevention exercise is supported due to its ability to greatly reduce hamstring injuries. 6 For example, in elite soccer players, high levels of eccentric hamstring strength have been shown to reduce the risk
Emma Sconce, Paul Jones, Ellena Turner, Paul Comfort and Philip Graham-Smith
Hamstring injury-risk assessment has primarily been investigated using isokinetic dynamometry. However, practical issues such as cost and availability limit the widespread application of isokinetics for injury-risk assessment; thus, field-based alternatives for assessing eccentric hamstring strength are needed.
The aim of this study was to investigate the validity of the angle achieved during Nordic hamstring lowers (break-point angle) as a field-based test for eccentric hamstring strength.
Sixteen male (n = 7) and female (n = 9) soccer players (mean ± SD age 24 ± 6 y, height 1.77 ± 0.12 m, and body mass 68.5 ± 16.5 kg) acted as subjects for the study.
Main Outcome Measures:
The authors explored relationships between the Nordic break-point angle (the point at which the subject can no longer resist the increasing gravitational moment during a Nordic hamstring lower) measured from video and isokinetic peak torque and angle of peak torque of right- and left-knee flexors.
The results revealed a meaningful relationship between eccentric knee-flexor peak torque (average of right and left limbs) and the Nordic break-point angle (r = −.808, r 2 = 65%, P < .00001). However, there was a weak relationship observed (r = .480, r 2 = 23%, P = .06) between break-point angle and the angle of peak torque (average of right and left limbs).
The results suggest that the break-point angle achieved during Nordic hamstring lowers could be used as a field-based assessment of eccentric hamstring strength.
Gulcan Harput, H. Erkan Kilinc, Hamza Ozer, Gul Baltaci and Carl G. Mattacola
There is lack of information related to quadriceps and hamstring strength recovery during the early period of rehabilitation after anterior cruciate ligament reconstruction (ACLR) using hamstring-tendon graft (HTG).
To investigate quadriceps and hamstring isometric strength at 4-, 8-, and 12-wk time points after ACLR and to document the strength changes of these muscles over time.
24 patients (age 28.1 ± 8.1 y) who underwent unilateral single-bundle anatomic ACLR with 4-strand semitendinosus and gracilis tendon graft.
Main Outcome Measures:
The isometric strength of quadriceps and hamstring muscles was measured on an isokinetic dynamometer at a 60° knee-flexion angle 4, 8, and 12 wk after surgery.
Quadriceps and hamstring strength significantly increased over time for both the involved limb (quadriceps F 2,46 = 58.3, P < .001; hamstring F 2,46 = 35.7, P < .001) and uninvolved limb (quadriceps F 2,46 = 17.9, P < .001; hamstring F 2,46 = 56.9, P = .001). Quadriceps and hamstring indexes significantly changed from 4 wk (QI 57.9, HI 54.4) to 8 wk (QI 78.8, HI 69.9) and from 8 wk to 12 wk (QI 82, HI 75.7) (P < .001); however, there was no difference between indexes at the 12-wk time point (P = .17).
The results of this study serve as a reference for clinicians while directing a rehabilitation protocol for HTG ACLR patients to better appreciate expected strength changes of the muscles in the early phase of recovery.
Diulian Muniz Medeiros, César Marchiori and Bruno Manfredini Baroni
flexion and the knee extension. 69 , 70 Therefore, it seems plausible that increasing eccentric strength might decrease the risk of sustaining an HSI. However, the literature is not definitive regarding the role of poor hamstring strength as a risk factor for HSI. For instance, Van Dyk et al 71
Martin Buchheit, Yannick Cholley, Mark Nagel and Nicholas Poulos
To examine the effect of body mass (BM) on eccentric knee-flexor strength using the Nordbord and offer simple guidelines to control for the effect of BM on knee-flexor strength.
Data from 81 soccer players (U17, U19, U21, senior 4th French division, and professionals) and 41 Australian Football League (AFL) players were used for analysis. They all performed 1 set of 3 maximal repetitions of the bilateral Nordic hamstring exercise, with the greatest strength measure used for analysis. The main regression equation obtained from the overall sample was used to predict eccentric knee-flexor strength from a given BM (moderate TEE, 22%). Individual deviations from the BM-predicted score were used as a BM-free index of eccentric knee- flexor strength.
There was a large (r = .55, 90% confidence limits .42;.64) correlation between eccentric knee-flexor strength and BM. Heavier and older players (professionals, 4th French division, and AFL) outperformed their lighter and younger (U17–U21) counterparts, with the soccer professionals presenting the highest absolute strength. Professional soccer players were the only ones to show strength values likely slightly greater than those expected for their BM.
Eccentric knee-flexor strength, as assessed with the Nordbord, is largely BM-dependent. To control for this effect, practitioners may compare actual test performances with the expected strength for a given BM, using the following predictive equation: Eccentric strength (N) = 4 × BM (kg) + 26.1. Professional soccer players with specific knee-flexor-training history and enhanced neuromuscular performance may show higher than expected values.
Dai Sugimoto, Benton E. Heyworth, Brandon A. Yates, Dennis E. Kramer, Mininder S. Kocher and Lyle J. Micheli
, the hamstrings, antagonists of the quadriceps, provide posterior shear forces on the tibia; thereby, counterbalancing the anterior shear force generated by the quadriceps and protecting the ACL from excessive loads. Thus, the specific balance between quadriceps and hamstrings strength is particularly
Christopher Michael Brogden, Lewis Gough and Adam Kelly
play. 4 , 12 Consequently, eccentric hamstring strength represents an appealing and modifiable risk factor for HSI, 13 with research demonstrating HSI to reduce by ∼70% when Nordic hamstring curl exercises are adopted as part of injury prevention programmes. 14 The IKD 15 has been proposed as the
Benjamin S. Killen, Krista L. Zelizney and Xin Ye
.42) muscle activities than SAFR did. Thus, in the current study, the near-medium effects that the SS imposed on the contralateral muscle activities might have contributed as a potential neural factor, partly affecting the contralateral hamstrings strength at a nonsignificant level. By contrast, after the