Comparison of The Effects of Nordic Hamstring and Single Leg Deadlift Exercises on Hamstring Muscle Strength and Extremity Symmetry Index: An Experimental Study

Abstract

Objective: The aim of this study is to compare the effects of 8-week Nordic hamstring exercise (NHE) and single leg deadlift exercise (SLDE) on hamstring (H) muscle peak torque (MPT), average power (AP) and extremity symmetry index (ESI).

Material and Methods: Thirty competetive male football players between the ages of 18-25 participated in the study. Participants were divided into three groups: control group (CG), Nordic hamstring exercise group (NHEG) and single leg deadlift exercise group (SLDEG). The participants' H muscle strength and ESI values were determined twice with the H-Bord device (IVMES, Türkiye), at the beginning of the training program and at the end of the eight-week program. Repeated Measures Two-Way ANOVA test was used to examine the results of different protocols, pre-post test measurements, and protocol*time interaction effect.

Results: A significant difference was found between CG and NHEG in both leg PT and mean power parameters in favor of NHEG. An improvement was determined in all groups in the right leg peak torque and average power parameters in favor of the post-test. In addition, a statistically significant difference was observed in the ESI parameter from the pre-test to the post-test only in NHEG.

Conclusion: Eccentric exercises NHE and SLDE are effective in improving H muscle strength with no significant differences.

Introduction

Hamstring (H) muscle strength plays an important role in providing knee joint stabilization, as well as directly affecting sports performance parameters such as agility, acceleration, deceleration, and change of direction [1,2]. Especially in team sports, low H muscle strength or insufficient activation increases the risk of injury such as anterior cruciate ligament and H muscle tears, along with other factors, as well as performance losses [3-8]. It has been shown that the most important preventive exercises in minimizing these injuries occurring in the H muscle are eccentric strength exercises and balance/proprioception exercises [9].

It has been shown that coaches ignore eccentric strength training and focus more on concentric strength training, In recent years, eccentric exercises, such as Nordic hamstring (NH) and single leg deadlift (SLD) exercises, which can be applied anywhere and do not require any equipment are included in strength training. There are studies indicating that NHE [10-12], and SLDE [13,14] both provide improvement in H muscle strength. However, the limited number of studies comparing the hamstring muscle peak torque (MPT), average power (AP), and ESI effects of these two exercises, as well as the lack of studies using devices that directly measure eccentric hamstring muscle strength, constitute the originality of our study.

Material and Methods

Participants

It was estimated that the 219±38 power value would be 243 with a 10% difference and calculated with 5% error and 80% power in the G*power 3.1.9.2 program and it was found that at least 24 people should participate in the study. 30 male participants who had no history of lower extremity injuries were included in the study (Table 1). Informed consent form was obtained from the participants. The necessary permission was obtained from the Nigde Ömer Halisdemir University Non-Interventional Clinical Research Ethics Committee for the study to be conducted (Ethics Committee Decision Number: 2022/08 Date: 17-01-2022). This study was conducted in accordance with the Helsinki Declaration 2008 Principles.

Research Design

Participants were randomly divided into three groups: the control group (CG) that did not perform any exercise other than soccer training, the Nordic hamstring exercise group (NHEG) that performed Nordic hamstring exercise in addition to soccer training, and the single leg deadlift exercise group (SLDEG) that performed single leg deadlift exercise in addition to soccer training. While all groups performed the same training with the soccer team 5 days a week, SLDEG and NHEG performed the specific exercise programs 3 days a week for 8 weeks in addition to soccer training immediately after warming up at the beginning of soccer training. All participants' H muscle MPT, AP, and ESI parameters were measured twice, before starting the exercise protocols and 8 weeks after the first measurements.

H Muscle Strength Measurement

The participants' H eccentric muscle strength was evaluated with H-Bord device (IVMES, Ankara, Turkey) [15]. The participants' ankles were fixed with tapes, and they started the movement on both knees of the H Board device, with the body in the same plane as the knees, in a straight and crossed position with the arms in front. Then, the participant slowly let himself go forward without changing his position, with the body in the same plane as the knees, with the knees fixed on the mechanism, and continued the movement until the last point he could reach in this position. While this movement was applied, the MPT as AP parameters of both leg H muscle groups were measured in Newtons by means of sensors located at the points connected to the ankles of the H-Board device [16]. The movement was performed twice with a 30-second interval and the best score in the study was obtained.

Nordic Hamstring Exercise

Participants commence the exercise in a kneeling posture, with the upper body from the knees upwards maintained in a rigid and aligned manner. The training partner guarantees that the participant's feet remain in contact with the ground throughout the duration of the exercise by exerting pressure on the participant's heels or lower legs. Subsequently, the participant descends the upper body towards the ground as gradually as feasible to optimize loading during the eccentric phase. The hands and arms are employed to mitigate the forward descent and to assist in elevating the body after the chest has made contact with the ground, thereby reducing loading during the concentric phase.

The participants performed the NHE in the 1st week, 2 sets of 8 repetitions; in the 2nd week, 2 sets of 10 repetitions; in the 3rd week, 2 sets of 12 repetitions; in the 4th week, 3 sets of 10 repetitions; Weeks 5-8 were applied as 3 sets of 12 repetitions with 2 minutes of rest between repetitions [16].

Single Leg Deadlift Exercise

To begin, the athlete stood on one leg with the core stabilized. In the descending phase, the knee joint of the loaded leg was slightly flexed, and the hip joint flexed while keeping the spine neutral. The hip and knee joints of the unloaded leg are maintained in extension, and the body is tilted so that the spine is parallel to the floor as much as possible. The distance of the athlete's movement depends on the athlete's flexibility of the hamstrings. Once the lowest point of the movement was reached, the athlete returned to the start positionwhile contracting the hamstrings and gluteus maximus muscles. The athletic trainer instructed the athletes to avoid spinal movement, hip rotation, and abduction of the loading leg during the SLRDL [17,18]. The exercise was applied to both extremities.

The participants performed the SLDE in the 1st week, 2 sets of 8 repetitions; in the 2nd week, 2 sets of 10 repetitions; in the 3rd week, 2 sets of 12 repetitions; in the 4th week, 3 sets of 10 repetitions; Weeks 5-8 were applied as 3 sets of 12 repetitions with 2 minutes of rest between repetitions.

Statistical Analysis

In this study, the assumption of normal distribution of quantitative variables was examined with visual (histogram and probability plots) and analytical (Shapiro-Wilk Test) methods. Quantitative variables were expressed as mean and standard deviation since they showed normal distribution. Repeated Measures two-way ANOVA test was used to examine the results of different protocols (CG, NHEG, SLDEG), pre- and post-test measurements, and protocol*time interaction effect. Mauchly sphericity test was used to test the homogeneity of variances and Greenhouse-Geisser correction was applied when necessary. Partial eta squares (ηp2) were calculated for the magnitude of the effect between the groups. When statistically significant differences were detected between the study protocols, multiple comparison analyses were performed using the Tukey method. p < 0.05 was considered significant.

Results

A statistically significant difference was found in the right leg peak torque (F=20.68; p=0.000, eta=0.48) and right leg average power (F=29.42; p=0.000, eta=0.52) parameters from pre-test to post-test in all groups. A statistically significant difference was found in the left leg peak torque (F=19.10; p=0.000, eta=0.41) and left leg average power (F=24.45; p=0.000, eta=0.47) parameters from pre-test to post-test in CG and NHEG. A statistically significant difference was found in the ESI (F=8.96; p=0.006, eta=0.424) parameter from pre-test to post-test in NHEG. There was a statistical difference between the groups in the parameters of right leg peak torque (F=10.11; p=0.001; eta=0.45), left leg peak torque (F=9.38; p=0.001; eta=0.41), right leg mean power (F=10.56; p=0.000; eta=0.43) and left leg mean power (F=9.56; p=0.001; eta=0.41). In the Benforroni correction, this difference was determined in favor of NHEG compared to CG.

Discussion

Athletes competing in team sports such as football, which are inherently hard and have a lot of dual combat, have a high risk of injury [19-21]. These athletes are most exposed to knee injuries (31.8%) and H injuries (12-16%) in the lower extremity [20, 22-24]. H injuries, which cause performance losses, are characterized by acute pain in the posterior thigh due to damage to the H muscle fibers [25]. Therefore, it is thought that improving the H muscle strength of athletes is of vital importance for coaches and athletes. Studies on H muscle strength, which is an important variable in both maximizing performance and preventing injuries in athletes, have also indicated that there is an improvement in H muscle strength and a decrease in injuries as a result of NHE and SLDE exercises applied to adult athletes [10-12]. Petersen et al. stated in their study on football players that NHE increased H strength development and also reduced the risk of H injuries [26]. Similarly, Askling et al. and Arnason et al. stated that NHE was the most effective exercise in increasing H muscle strength and preventing H injuries [10,27]. Ono et al. found that the other exercise method used in our study, SLDE, increased H muscle strength and reduced the risk of H injuries [13].

Hegyi et al. applied the NHE and SLDE exercises to 12 male participants and reported that the loads applied to the long head of the biceps femoris and the semitendinosus muscles during these exercises were not the same [28]. Another study examined the effects of SLDE and NHE applied for 6 months on isokinetic H strength, H/Q ratio, and H muscle architecture, and as a result of the study, it was determined that only SLDE had positive effects on H muscle hypertrophy, H muscle strength and H/Q ratio [13]. This different result presented by Ono et al. may be due to the fact that the exercise programs they applied in their study were applied for a much longer period than our study, such as 6 months, and the frequency and number of repetitions in the exercise protocols had different contents [13]. Another study investigated the effects of NHE and SLDE on fatigue in the H muscle after repeated sprinting. As a result of the study, it was determined that SLDE is an effective exercise to reduce the effects of fatigue and protect against H injuries, and it was also determined that the strength increase was higher in SLDE [14].

Although some of the above-mentioned studies show that NHE is more effective in developing H muscle strength, and some show that SLDE is more effective, there is no consensus on which exercise provides better outcomes. In our study, although the H muscle strengths of the groups increased, but contrary to the studies in the literature, no difference was found between SLDEG and NHEG.

Limiting the sample to male football players competing in amateur league represents a limitation of the present study.

Conclusion

Athletes aiming to enhance their H muscle strength can opt for either SLDE or NHE, as both exercises facilitate similar improvements.

Cite as: Aka H, Ibis S, Aktug ZB, Yavuz G. Comparison of The Effects of Nordic Hamstring and Single Leg Deadlift Exercises on Hamstring Muscle Strength and Extremity Symmetry Index: An Experimental Study.Turk J Sports Med. 2026; https://doi.org/10.47447/tjsm.0898

The study was approved by the local ethics committee (approve date 17.01.2022 and number 2022/08) and performed accordingto Helsinki declaration criteria.

Concept: HA, ZBA; design: HA, ZBA, GY; supervision: HA, ZBA, GY; materials: ZBA, GY; data collection and processing: HA, ZBA, Sİ; analysis and interpretation: HA, Sİ; literature review: HA, ZBA, GY; writing manuscript: HA, Sİ, GY; critical review: ZBA, Sİ. All authors contributed to the final version of the manuscript and discussed the results and contributed to the final manuscript.

The authors declared no conflicts of interest with respect to authorship and/or publication of the article.

This study was supported by Nigde Ömer Halisdemir Universty Research Projects Coordination Unit Coordinatorship. Project No: 2023/08/24

References

1. Greig M, Naylor J. The efficacy of angle-matched isokinetic knee flexor and extensor strength parameters in predicting agility test performance. Int J Sports Phys Ther. 2017;(12):728-36.
2. Jones PA, Thomas C, Dos'Santos R, McMahon JJ, Graham-Smith P. The role of eccentric strength in 180° turns in female soccer players. Sports. 2017;5(2):42.
3. Zebis MK, Skotte J, Andersen CH, Mortensen P, Petersen HH, Viskaer TC, et al. Kettlebell swing targets semitendinosus and supine leg curl targets biceps femoris: an EMG study with rehabilitation implications. Br J Sports Med. 2013;(47):1192-8.
4. Engebretsen AH, Myklebust G, Holme I, Engebretsen L, Bahr R. Intrinsic risk factors for H injuries among male soccer players: a prospective cohort study. Am J Sports Med. 2010;38(6):1147-53.
5. Cloke D, Moore O, Shah T, Rushton S, Shirley MD, Deehan DJ. Thigh muscle injuries in youth soccer: predictors of recovery. Am J Sports Med. 2012;40(2):433-9.
6. Freckleton G, Pizzari T. Risk factors for H muscle strain injury in sport: a systematic review and meta-analysis. Br. J. Sports Med. 2013;47(6):351-8.
7. van Beijsterveldt AMC, van der Horst N, van de Port IGL, Backx FJG. How effective are exercise-based injury prevention programmes for soccer players? A systematic review. Sports Med. 2013;43(4):257-65.
8. Opar DA, Williams MD, Shield AJ. Hamstring strain injuries. Sports Med. 2012;42(3):209-26.
9. McCall A, Carling C, Davison M, Nedelec M, Le Gall F, Berthoin S, et al. Injury risk factors, screening tests and preventative strategies: a systematic review of the evidence that underpins the perceptions and practices of 44 football (soccer) teams from various premier leagues. Br J Sports Med. 2015;49(9):583-9.
10. Askling C, Karlsson J, Thorstensson A. Hamstring injury occurrence in elite soccer players after preseason strength training with eccentric overload. Scand J Med Sci Sports. 2003;(13):244-50.
11. Mjolsnes R, Arnason A, Osthagen T, Raastad T, Bahr RA. 10-week randomized trial comparing eccentric vs. concentric hamstring strength training in well-trained soccer players. Scand J Med Sci Sports. 2004;14(5);311-7.
12. Iga J, Fruer CS, Deighan M, Croix MD, James DV. Nordic hamstrings exercise engagement characteristics and training responses. Int J Sports Med. 2012;33(12):1000-4.
13. Ono T, Tojima M, Hirose N. Hamstrings training effect on hip and knee joint function, morphology of hamstring muscles, and injury prevention. Br J Sports Med. 2017;51(4):368.
14. Freeman BW, Young WB, Talpey SW, Smyth AM, Pane CL, Carlon TAJ. The effects of Sprint Training and the Nordic Hamstring Exercise on eccentric hamstring strength and sprint performance in adolescent athletes. Sports Med Phys Fitness. 2019;59(7):1119-25.
15. Akarcesme C, Cengizel E, Alvurdu S, Bağcı E, Altundağ E, Cengizel CO, et al. Reliability and validity of the newportable nordic hamstring test device (IVMES H-Bord). J Sports Eng Tech. 2024;24(4):1024-1031.
16. Pişkin NE, Yavuz G, Aktuğ ZB, Aldhahi MI, Al-Mhanna SB, Gülü M. The effect of combining blood flow restriction with the nordic hamstring exercise on hamstring strength: randomized controlled trial. J Clin Med. 2024;13(7): 2035.
17. Weaver AN, Kerksick CM. Implementing landmine single leg romanian deadlift into an athlete's training program. Strength Condit J. 2017;39(1):85-95.
18. McCunn R, Aus der Fünten K, Govus A, Julian R, Schimpchen J, Meyer T. The intra- and inter-rater reliability of the Soccer Injury Movement Screen (SIMS). Int J Sports Phys Ther. 2017;12(1):53-66.
19. Schmikli SL, de Vries WR, Inklaar H, Backx FJ. Injury prevention target groups in soccer: injury characteristics and incidence rates in male junior and senior players. J Sci Med Sport. 2011;14(3):199-203.
20. Ekstrand J, Hagglund M, Walde´n M. Injury incidence and injury patterns in professional football: the UEFA injury study. Br J Sports Med. 2011;45(7):553-558.
21. van Beijsterveldt AMC, Stubbe JH, Schmikli SL, van de Port IGL, Backx FJG. Differences in injury risk and characteristics between Dutch amateur and professional soccer players. J Sci Med Sport.2014;18(2):145-149.
22. Giza E, Mithofer K, Farrell L, Zarins B, Gill T, Drawer S. Injuries in women's professional soccer. Br J Sport Med. 2005;39(4):212-216.
23. Venturelli M, Schena F, Zanolla L, Bishop D. Injury risk factors in young soccer players detected by a multivariate survival model. J Sci Med Sport. 2011;14(4):293-298.
24. Woods C, Hawkins RD, Maltby S, Hulse M, Thomas A, Hodson A. The football association medical research programme: an audit of injuries in professional football-analysis of hamstring injuries. Br J Sports Med. 2004;38:36-41.
25. Verrall GM, Slavotinek JP, Barnes PG, Fon G, Spriggins A. Clinical risk factors for hamstring muscle strain injury: a prospective study with correlation of injury by magnetic resonance imaging. Br J Sports Med. 2001;35(6):435-9.
26. Petersen J, Thorborg K, Nielsen MB, Budt-Jørgensen E, Holmich P. Preventive effect of eccentric training on acute hamstring injuries in men's soccer: a cluster-randomized controlled trial. Am J Sports Med.2011;39(11):2296-2303.
27. Arnason A, Andersen TE., Holme I, Engebretsen L, Bahr R. Prevention of hamstring strains in elite soccer: an intervention study. Scand J Med Sci Sports. 2008;18(1):40-48.
28. Hegyi A, Péter A, Finni T, Cronin NJ. Region-dependent hamstrings activity in Nordic hamstring exercise and stiff-leg deadlift defined with high-density electromyography. Scand J Med Sci Sports. 2018;28(3):992-1000.