Elsevier

Physical Therapy in Sport

Volume 40, November 2019, Pages 10-18
Physical Therapy in Sport

Original Research
Progressive strength training restores quadriceps and hamstring muscle strength within 7 months after ACL reconstruction in amateur male soccer players

https://doi.org/10.1016/j.ptsp.2019.08.004Get rights and content

Highlights

  • Soccer players after ACLR showed similar muscle strength at 7 months compared to controls.

  • Sixty-five percent of soccer players after ACLR passed LSI >90% for quadriceps muscle strength at 10 months.

  • Soccer players after ACLR showed good self-reported knee function at 10 months.

Abstract

Objectives

The purpose of the current study was to compare the results of a progressive strength training protocol for soccer players after anterior cruciate ligament reconstruction (ACLR) with healthy controls, and to investigate the effects of the strength training protocol on peak quadriceps and hamstring muscle strength.

Design

Between subjects design.

Setting

Outpatient physical therapy facility.

Participants

Thirty-eight amateur male soccer players after ACLR were included. Thirty age-matched amateur male soccer players served as control group.

Main outcome measures

Quadriceps and hamstring muscle strength was measured at three time points during the rehabilitation. Limb symmetry index (LSI) > 90% was used as cut-off criteria.

Results

Soccer players after ACLR had no significant differences in peak quadriceps and hamstring muscle strength in the injured leg at 7 months after ACLR compared to the dominant leg of the control group. Furthermore, 65.8% of soccer players after ACLR passed LSI >90% at 10 months for quadriceps muscle strength.

Conclusion

Amateur male soccer players after ACLR can achieve similar quadriceps and hamstring muscle strength at 7 months compared to healthy controls. These findings highlight the potential of progressive strength training in rehabilitation after ACLR that may mitigate commonly reported strength deficits.

Introduction

One of the main components in early rehabilitation after anterior cruciate ligament reconstruction (ACLR) in soccer is restoring quadriceps and hamstring strength before on-field rehabilitation and return to sport (RTS) starts (Della Villa et al., 2012). Symmetrical quadriceps muscle strength prior to RTS has been suggested to be associated with a reduction in the re-injury risk (Grindem et al., 2016, Kyritsis et al., 2016). Furthermore, it has been reported that quadriceps muscle strength is associated with good self-reported knee function and patient satisfaction after ACLR (Logerstedt et al., 2014). It is common to calculate a limb symmetry index (LSI) for quadriceps and hamstring strength, defined as peak muscle strength of the injured leg divided by peak muscle strength of the non-injured leg x 100 (Lynch et al., 2015). To determine readiness for RTS, LSI criteria >90% are often used as cut-off scores (Lynch et al., 2015).

Unfortunately, recent studies showed that most patients after ACLR failed in passing RTS criteria for quadriceps muscle strength at 6 and 9 months after ACLR (Gokeler et al., 2017b, Toole et al., 2017, Welling et al., 2018). According to some researchers (Nagelli & Hewett, 2017), restoring quadriceps muscle strength requires prolonged rehabilitation after ACLR of up to a minimum of 2 years. Another perspective is to look critically at the content of rehabilitation. Muscle strength deficits following ACLR can be due to insufficient rehabilitation protocols (Thomee et al., 2011). Strength training intensity and volume might be too low to increase muscle strength and muscle volume to satisfactory levels (Gokeler et al., 2017b, Welling et al., 2018). In addition, research emphasized the need for a more detailed documentation of strength training protocol after ACLR (Augustsson, 2013, Goff et al., 2018). The American College of Sports Medicine (ACSM) recommends that strength training must be completed with a frequency of two to three times per week, with two to four sets of exercises (8–12 repetitions) at 60%–80% (moderate to hard intensity) of one-repetition maximal (1RM) effort, including 2–3 min of rest between the exercises to regain muscle hypertrophy and strength in healthy individuals (Garber et al., 2011). By manipulating several aspects of the strength training (frequency, number of repetitions, unilateral and bilateral exercises), it is possible to perform strength training in a progressive manner (Garber et al., 2011, Ratamess et al., 2009, Schoenfeld, 2010). In addition, variation of exercises within strength training is suggested to enhance physical performance of the athlete (Ratamess et al., 2009, Schoenfeld, 2010).

Currently, most athletes after ACLR fail in passing RTS quadriceps muscle strength criteria and the ACSM has several recommendations for strength training to regain muscle strength. In addition, research found greater quadriceps deficits (lower LSI values) in patients after ACLR with a bone-patellar tendon-bone graft (BPTB) graft compared to a hamstring tendon graft (HT) using standardized rehabilitation (Welling et al., 2018). On the other hand, greater hamstring deficits were found in patients after ACLR with HT graft compared to BPTB graft (Hughes et al., 2019).

The primary purpose of the current study was to compare the results of a strength training protocol for soccer players after ACLR with healthy controls, and to investigate the effects of the strength training protocol on peak quadriceps and hamstring muscle strength and self-reported knee function during rehabilitation after ACLR. The secondary purpose was to investigate the differences between soccer players after ACLR with HT graft and BPTB graft in peak quadriceps and hamstring muscle strength during the course of rehabilitation after ACLR. It was hypothesized that soccer players after ACLR showed comparable peak quadriceps and hamstring muscle strength and LSI values after training compared to healthy controls. Additionally, it was hypothesized that peak quadriceps and hamstring muscle strength significantly improves over time as well as self-reported knee function as a result of the strength training. Also, it was hypothesized that soccer players after ACLR with HT graft show greater peak quadriceps muscle strength and weaker peak hamstring muscle strength compared to those with a BPTB graft.

Section snippets

Participants

Thirty-eight amateur male soccer players (age 24.2 ± 4.7 years) after ACLR participated in this study. The soccer players were recruited one-to-one in person in the physical therapy facility based on the inclusion criteria. For 29 soccer players after ACLR (76.3%) the injured leg was the dominant leg, defined as the preferred leg to kick a ball (Padua et al., 2009, Welling et al., 2016). A power analysis (G*Power, Version 3.1.7) was used to calculate the required sample size for the soccer

Main findings

Analysis of the demographic variables between groups showed that the soccer players after ACLR had more body weight compared to the control group (79.0 ± 13.3 vs. 72.7 ± 6.8 kg; p = 0.018) (Table 1). The soccer players after ACLR had significant weaker peak quadriceps muscle strength in the injured leg at 4 months compared to the dominant leg of the control group (188.6 ± 51.6 vs. 231.7 ± 27.0 Nm; p < 0.001) (Table 3). At 7 months however, there were no significant differences in peak

Main findings

The primary findings of the current study were that soccer players 7 months after ACLR showed no significant differences in peak quadriceps and hamstring muscle strength compared to the control group. At 10 months, the soccer players after ACLR were stronger than control group. Furthermore, 65.8% of the soccer players after ACLR passed LSI >90% at 10 months for quadriceps muscle strength and 76.3% for hamstring muscle strength. Additionally, self-reported knee function progressed over time. The

Conclusions

The results show that by using principles of progressive strength training, soccer players who underwent an ACLR regain quadriceps and hamstring muscle strength comparable to healthy controls at 7 months after ACLR. At 10 months, the soccer players after ACLR were stronger compared to healthy controls. In addition, passing LSI >90% for quadriceps muscle strength was achieved by 65.8% of the soccer players after ACLR and 76.3% for hamstrings strength 10 months after ACLR. Also, soccer players

Declarations of interest

None.

Conflicts of interest

None.

Ethical approval

Work has been approved by the ethical committees of the University of Groningen.

Funding

None declared.

Acknowledgements

The authors would like to acknowledge T.P.C. Franke (PT, MSc) and D. Peeters (PT, BSc) for their contribution in describing the rehabilitation protocol.

References (47)

  • M. Buckthorpe

    Optimising the late-stage rehabilitation and return-to-sport training and testing process after ACL reconstruction

    Sports Medicine

    (2019)
  • M. Buckthorpe et al.

    Restoring knee extensor strength after anterior cruciate ligament reconstruction: A clinical commentary

    International Journal of Sports Physical Therapy

    (2019)
  • J. Cohen

    Statistical power analysis for the behavioral sciences

    (1988)
  • S. Della Villa et al.

    Clinical outcomes and return-to-sports participation of 50 soccer players after anterior cruciate ligament reconstruction through a sport-specific rehabilitation protocol

    Sports Health

    (2012)
  • B. Dingenen et al.

    Optimization of the return-to-sport paradigm after anterior cruciate ligament reconstruction: A critical step back to move rorward

    Sports Medicine

    (2017)
  • C.E. Garber et al.

    American College of sports medicine position stand. Quantity and quality of exercise for developing and maintaining cardiorespiratory, musculoskeletal, and neuromotor fitness in apparently healthy adults: Guidance for prescribing exercise

    Medicine & Science in Sports & Exercise

    (2011)
  • A. Ghasemi et al.

    Normality tests for statistical analysis: A guide for non-statisticians

    International Journal of Endocrinology and Metabolism

    (2012)
  • A. Gokeler et al.

    Feedback techniques to target functional deficits following anterior cruciate ligament reconstruction: Implications for motor control and reduction of second injury risk

    Sports Medicine

    (2013)
  • A. Gokeler et al.

    Quadriceps function following ACL reconstruction and rehabilitation: Implications for optimisation of current practices

    Knee Surgery, Sports Traumatology, Arthroscopy

    (2014)
  • A. Gokeler et al.

    Development of a test battery to enhance safe return to sports after anterior cruciate ligament reconstruction

    Knee Surgery, Sports Traumatology, Arthroscopy

    (2017)
  • H.T. Grevnerts et al.

    The measurement properties of the IKDC-subjective knee form

    Knee Surgery, Sports Traumatology, Arthroscopy

    (2015)
  • H. Grindem et al.

    Simple decision rules can reduce reinjury risk by 84% after ACL reconstruction: The Delaware-oslo ACL cohort study

    British Journal of Sports Medicine

    (2016)
  • T. Harbo et al.

    Maximal isokinetic and isometric muscle strength of major muscle groups related to age, body mass, height, and sex in 178 healthy subjects

    European Journal of Applied Physiology

    (2012)
  • Cited by (43)

    • Return to sport soccer after anterior cruciate ligament reconstruction: ISAKOS consensus

      2022, Journal of ISAKOS
      Citation Excerpt :

      Progressive strength training in ACL rehabilitation can mitigate commonly reported strength deficits [40]. If proper progressive strength training is implemented, amateur male soccer players after ACL reconstruction achieve similar knee strength after ACLR at 7 months compared to healthy controls [97]. ACL rehabilitation progression should be based on objective criteria and not just time frames [83].

    • The modifying factors that help improve anterior cruciate ligament reconstruction rehabilitation: A narrative review

      2022, Annals of Physical and Rehabilitation Medicine
      Citation Excerpt :

      For the strengthening and neuromuscular rehabilitation phase, the exercises are the same as for a hamstring graft. The specific exercises for strengthening are important, and quadriceps open kinetic chain exercises [10] must be associated with the other exercises in closed kinetic chain recommended for the gain of muscular strength [15]. Special attention should be placed on the presence of anterior knee pain, a common complication of BPTB ACL reconstruction [16].

    • Effectiveness of a supervised rehabilitation compared with a home-based rehabilitation following anterior cruciate ligament reconstruction: A systematic review and meta-analysis

      2022, Physical Therapy in Sport
      Citation Excerpt :

      Second, the earlier review found no difference in knee extension and flexion strength at any time points, except for eccentric knee extension strength at 3–6 months; however, these outcomes are reported as Lim Symmetry Index (LSI), which measures strength in the affected limb as the percentage of unaffected limb (Barber-Westin & Noyes, 2011; Garcia, Rodriguez, Krishnan, & Palmieri-Smith, 2020; Hiemstra, Webber, MacDonald, & Kriellaars, 2007; Palmieri-Smith, Thomas, & Wojtys, 2008; Urbach, Nebelung, Becker, & Awiszus, 2001). While several studies have used the LSI as a useful strength measurement (Barber-Westin & Noyes, 2011; Garcia et al., 2020; Welling, Benjaminse, Lemmink, Dingenen, & Gokeler, 2019), other observational studies found bilateral muscle strength deficits following ACL (Garcia et al., 2020; Wellsandt, Failla, & Snyder-Mackler, 2017); thus, the LSI may overestimate knee function in individuals with ACL injuries (Wellsandt et al., 2017). To advance our knowledge on ACL rehabilitation, it is necessary to investigate the effects of SVR versus HBR on a wider range of outcomes, including knee strength without normalization by the uninvolved limb and at more specific timepoints (i.e., at a 6-month timepoint following the completion of interventions).

    View all citing articles on Scopus
    View full text