Advertisement
Letter to the editor| Volume 144, P206-208, April 2022

Why clinical context and relevant protocols matter: response to Impellizzeri et al.

  • Lasse Ishøi
    Correspondence
    Corresponding author. L. Ishøi., Tel :. +45 20438110
    Affiliations
    Sports Orthopedic Research Center – Copenhagen (SORC-C), Department of Orthopedic Surgery, Copenhagen University Hospital, Kettegaard Allé 30, Copenhagen, Denmark
    Search for articles by this author
  • Kristian Thorborg
    Affiliations
    Sports Orthopedic Research Center – Copenhagen (SORC-C), Department of Orthopedic Surgery, Copenhagen University Hospital, Kettegaard Allé 30, Copenhagen, Denmark

    Physical Medicine & Rehabilitation Research – Copenhagen (PMR-C), Department of Orthopedic Surgery and Physical Therapy, Copenhagen University Hospital, Kettegaard Allé 30, Copenhagen, Denmark

    Department of Clinical Medicine, University of Copenhagen, Kettegaard Allé 30, Copenhagen, Denmark
    Search for articles by this author
Published:November 01, 2021DOI:https://doi.org/10.1016/j.jclinepi.2021.10.021
Why clinical context and relevant protocols matter: response to Impellizzeri et al.
Previous ArticleSankey diagrams can clarify ‘evidence attrition’: A systematic review and meta-analysis of the effectiveness of rapid diagnostic tests for antimicrobial resistance
Next ArticleWhy clinical context and relevant protocols matter: author's reply
      We have with great interest read the paper by Impellizzeri et al. [

      Impellizzeri FM, McCall A, van Smeden M. Why methods matter in a meta-analysis: a reappraisal showed inconclusive injury preventive effect of Nordic hamstring exercise. J Clin Epidemiol [Internet]. 11. september 2021 [henvist 21. september 2021]; Tilgængelig hos: https://www.sciencedirect.com/science/article/pii/S08954356210028702.

      ] and agree with the criticism of previous meta-analyses, by Van Dyk et al. [

      Dyk N van, Behan FP, Whiteley R. Including the Nordic hamstring exercise in injury prevention programmes halves the rate of hamstring injuries: a systematic review and meta-analysis of 8459 athletes. Br J Sports Med2019;bjsports-2018-100045. doi:10.1136/bjsports-2018-100045

      ] and Al Attar et al. [
      • Al Attar WSA
      • Soomro N
      • Sinclair PJ
      • Pappas E
      • Sanders RH
      • et al.
      Effect of injury prevention programs that include the Nordic hamstring exercise on hamstring injury rates in soccer players: a systematic review and meta-analysis.
      Sports Med. 2017; 47: 907-916https://doi.org/10.1007/s40279-016-0638-2
      ], where they: combine both randomized and nonrandomized studies, and include studies examining the combined effect of exercises, including the Nordic hamstring exercise. Several studies in both meta-analyses concerns the FIFA 11+ programme, which has a preventive effect on hamstring injuries [
      • Thorborg K
      • Krommes KK
      • Esteve E
      • Clausen MB
      • Bartels EM
      • Rathleff MS
      • et al.
      Effect of specific exercise-based football injury prevention programmes on the overall injury rate in football: a systematic review and meta-analysis of the FIFA 11 and 11+ programmes.
      Br J Sports Med. 2017; 51: 562-571https://doi.org/10.1136/bjsports-2016-097066
      ]. Thus, the effectiveness cannot be attributed to the Nordic hamstring exercise alone, as correctly pointed out by Impellizzeri et al. [

      Impellizzeri FM, McCall A, van Smeden M. Why methods matter in a meta-analysis: a reappraisal showed inconclusive injury preventive effect of Nordic hamstring exercise. J Clin Epidemiol [Internet]. 11. september 2021 [henvist 21. september 2021]; Tilgængelig hos: https://www.sciencedirect.com/science/article/pii/S08954356210028702.

      ]. The authors should be congratulated for raising awareness about robust methodology concerning meta-analyses.
      Since Impellizzeri et al. [

      Impellizzeri FM, McCall A, van Smeden M. Why methods matter in a meta-analysis: a reappraisal showed inconclusive injury preventive effect of Nordic hamstring exercise. J Clin Epidemiol [Internet]. 11. september 2021 [henvist 21. september 2021]; Tilgængelig hos: https://www.sciencedirect.com/science/article/pii/S08954356210028702.

      ] performed an updated analysis of Van Dyk et al. [

      Dyk N van, Behan FP, Whiteley R. Including the Nordic hamstring exercise in injury prevention programmes halves the rate of hamstring injuries: a systematic review and meta-analysis of 8459 athletes. Br J Sports Med2019;bjsports-2018-100045. doi:10.1136/bjsports-2018-100045

      ] using improved methodology and included new studies, we were missing a thorough specification around the aim and hypothesis. This would have provided clinical context, especially considering the substantial heterogeneity (I2 = 65%) driven by the excessive clinical diversity across studies. It seems that the aim was to understand the preventive effectiveness of the Nordic hamstring exercise in athletes; however, evaluating strength exercises alone without specific context to the population they are tested in, or the exercise protocol applied is of very limited clinical value (Table 1). The first question
      Table 1Overview of Nordic Hamstring intervention protocols applied in randomized controlled trials
      WeekRepetitionsSetsSessions/wkRepetitions/wkTotal repetitions
      Petersen et al. 2011152110718 + maintenance during season
      26224
      36–83354–72
      48–1072–90
      5–1012, 10, 890
      Maintenance12, 10, 8130
      Van der Horst et al. 2015
      152110598
      26224
      3336
      46, 7, 842
      58, 9, 1054
      6–1310, 9, 854
      Sebelien et al. 2014
      152110277 + maintenance during season
      26224
      36–83354–72
      412, 10, 890
      590
      Maintenance12, 10, 890
      Hasebe al. 2020
      1521101264
      2–36224
      4–6336
      7–96, 7, 842
      10–138, 9, 1054
      14–2710, 9, 854
      Engebretsen et al. 2008
      Engebretsen et al. 2008 and Gabbe et al. 2008 separates from the remaining studies by: (1) including only football (soccer) players with a previous hamstring strain injury or defined poor hamstring function (Engebretsen et al. 2008) and (2) by including an extreme high volume per session protocol very different to the remaining studies in Australian Football players (Gabbe et al. 2008).
      152110718
      26224
      36–83354–72
      48–1072–90
      5–1012, 10, 890
      Gabbe et al. 2008
      Engebretsen et al. 2008 and Gabbe et al. 2008 separates from the remaining studies by: (1) including only football (soccer) players with a previous hamstring strain injury or defined poor hamstring function (Engebretsen et al. 2008) and (2) by including an extreme high volume per session protocol very different to the remaining studies in Australian Football players (Gabbe et al. 2008).
      1612172360
      2----
      3612172
      4----
      5612172
      6–8----
      9612172
      10–11----
      12612172
      a Engebretsen et al. 2008 and Gabbe et al. 2008 separates from the remaining studies by: (1) including only football (soccer) players with a previous hamstring strain injury or defined poor hamstring function (Engebretsen et al. 2008) and (2) by including an extreme high volume per session protocol very different to the remaining studies in Australian Football players (Gabbe et al. 2008).
      asked when introducing an exercise in a specific team setting is often “how many should be done and for how long!”
      Although the meta-analysis by Impellizzeri et al. [

      Impellizzeri FM, McCall A, van Smeden M. Why methods matter in a meta-analysis: a reappraisal showed inconclusive injury preventive effect of Nordic hamstring exercise. J Clin Epidemiol [Internet]. 11. september 2021 [henvist 21. september 2021]; Tilgængelig hos: https://www.sciencedirect.com/science/article/pii/S08954356210028702.

      ] is an interesting post hoc analysis, on unspecified use of the Nordic hamstring exercise, we do not believe it can inform clinical practice about football (soccer).
      If we want to know the preventative effectiveness of the Nordic hamstring protocol on team level in male football, some studies need to be removed from the updated analysis by Impellizzeri et al. [

      Impellizzeri FM, McCall A, van Smeden M. Why methods matter in a meta-analysis: a reappraisal showed inconclusive injury preventive effect of Nordic hamstring exercise. J Clin Epidemiol [Internet]. 11. september 2021 [henvist 21. september 2021]; Tilgængelig hos: https://www.sciencedirect.com/science/article/pii/S08954356210028702.

      ] First, we propose to remove Engebretsen et al. [
      • Engebretsen AH
      • Myklebust G
      • Holme I
      • Engebretsen L
      • Bahr R
      • et al.
      Prevention of injuries among male soccer players: a prospective, randomized intervention study targeting players with previous injuries or reduced function.
      Am J Sports Med. 2008; 36: 1052-1060https://doi.org/10.1177/0363546508314432
      ] as they only included players with a previous hamstring injury and/or poor self-reported hamstring function, and thus representing a subgroup of football players, and not a full football team. Secondly, the pilot study by Gabbe et al. [
      • Gabbe BJ
      • Branson R
      • Bennell KL.
      A pilot randomised controlled trial of eccentric exercise to prevent hamstring injuries in community-level Australian Football.
      J Sci Med Sport. 2006; 9: 103-109https://doi.org/10.1016/j.jsams.2006.02.001
      ] introduced a very high session volume approach (starting with 72 repetitions in the initial session), which has never been used since in the literature or clinically to the best of our knowledge, in a different football code (Australian Football).
      Notably, by removing these two studies from the updated meta-analysis by Impellizzeri et al. [

      Impellizzeri FM, McCall A, van Smeden M. Why methods matter in a meta-analysis: a reappraisal showed inconclusive injury preventive effect of Nordic hamstring exercise. J Clin Epidemiol [Internet]. 11. september 2021 [henvist 21. september 2021]; Tilgængelig hos: https://www.sciencedirect.com/science/article/pii/S08954356210028702.

      ], the heterogeneity becomes minimal (I2 = 7.0%) and uncertainty lower with the prediction interval not crossing a risk ratio of 1 (Fig. 1). This has a direct impact on the quality of evidence, and recommendations, since this affects the Inconsistency (high heterogeneity across studies), Indirectness (application of the findings), and Imprecision (wide confidence intervals) domains of the GRADE [
      • Guyatt GH
      • Oxman AD
      • Kunz R
      • Brozek J
      • Alonso-Coello P
      • Rind D
      • et al.
      GRADE guidelines 6. Rating the quality of evidence–imprecision.
      J Clin Epidemiol. 2011; 64: 1283-1293https://doi.org/10.1016/j.jclinepi.2011.01.012
      ,
      • Guyatt GH
      • Oxman AD
      • Kunz R
      • Woodcock J
      • Brozek J
      • Helfand M
      • et al.
      GRADE guidelines: 8. Rating the quality of evidence–indirectness.
      J Clin Epidemiol. 2011; 64: 1303-1310https://doi.org/10.1016/j.jclinepi.2011.04.014
      ,
      • Guyatt GH
      • Oxman AD
      • Kunz R
      • Woodcock J
      • Brozek J
      • Helfand M
      • et al.
      GRADE guidelines: 7. Rating the quality of evidence–inconsistency.
      J Clin Epidemiol. 2011; 64: 1294-1302https://doi.org/10.1016/j.jclinepi.2011.03.017
      ].
      Fig. 1
      Fig. 1Meta-analysis of the effectiveness of the Nordic Hamstring exercise on hamstring injuries in male football (soccer) players using a Nordic Hamstring protocol. The methodology of the of meta-analysis is identical to the updated meta-analysis by Impellizzeri et al.
      [

      Impellizzeri FM, McCall A, van Smeden M. Why methods matter in a meta-analysis: a reappraisal showed inconclusive injury preventive effect of Nordic hamstring exercise. J Clin Epidemiol [Internet]. 11. september 2021 [henvist 21. september 2021]; Tilgængelig hos: https://www.sciencedirect.com/science/article/pii/S08954356210028702.

      ]
      by using the r code provided by within that paper.
      We agree that the preventive effectiveness of the Nordic hamstring exercise may be inconclusive in athletes when context and protocols are disregarded. However, the Nordic hamstring exercise seems to be effective (and importantly, not harmful) when applied at team level in male football players using a Nordic hamstring protocol as your intervention [
      • Petersen J
      • Thorborg K
      • Nielsen MB
      • Budtz-Jorgensen E
      • Holmich P
      • et al.
      Preventive effect of eccentric training on acute hamstring injuries in men’s soccer: a cluster-randomized controlled trial.
      Am J Sports Med. 2011; 39: 2296-2303https://doi.org/10.1177/0363546511419277
      ,
      • Sebelien C
      • Stiller C H
      • Maher S F
      • Qu X
      • et al.
      Effects of implementing Nordic hamstring exercises for semi-professional soccer players in Akershus, Norway.
      Ortopeadic Pract. 2014; 26: 90-97
      ,
      • Hasebe Y
      • Akasaka K
      • Otsudo T
      • Tachibana Y
      • Hall T
      • Yamamoto M
      • et al.
      Effects of nordic hamstring exercise on hamstring injuries in high school soccer players: a randomized controlled trial.
      Int J Sports Med. 2020; 41: 154-160https://doi.org/10.1055/a-1034-7854
      ,
      • van der Horst N
      • Smits DW
      • Petersen J
      • Goedhart EA
      • Backx FJ
      • et al.
      The preventive effect of the nordic hamstring exercise on hamstring injuries in amateur soccer players: a randomized controlled trial.
      Am J Sports Med. 2015; 43: 1316-1323https://doi.org/10.1177/0363546515574057
      ].

      References

      1. Impellizzeri FM, McCall A, van Smeden M. Why methods matter in a meta-analysis: a reappraisal showed inconclusive injury preventive effect of Nordic hamstring exercise. J Clin Epidemiol [Internet]. 11. september 2021 [henvist 21. september 2021]; Tilgængelig hos: https://www.sciencedirect.com/science/article/pii/S08954356210028702.

        View in Article

      2. Dyk N van, Behan FP, Whiteley R. Including the Nordic hamstring exercise in injury prevention programmes halves the rate of hamstring injuries: a systematic review and meta-analysis of 8459 athletes. Br J Sports Med2019;bjsports-2018-100045. doi:10.1136/bjsports-2018-100045

        View in Article
        • Al Attar WSA
        • Soomro N
        • Sinclair PJ
        • Pappas E
        • Sanders RH
        • et al.
        Effect of injury prevention programs that include the Nordic hamstring exercise on hamstring injury rates in soccer players: a systematic review and meta-analysis.
        Sports Med. 2017; 47: 907-916https://doi.org/10.1007/s40279-016-0638-2
        View in Article
        • Thorborg K
        • Krommes KK
        • Esteve E
        • Clausen MB
        • Bartels EM
        • Rathleff MS
        • et al.
        Effect of specific exercise-based football injury prevention programmes on the overall injury rate in football: a systematic review and meta-analysis of the FIFA 11 and 11+ programmes.
        Br J Sports Med. 2017; 51: 562-571https://doi.org/10.1136/bjsports-2016-097066
        View in Article
        • Engebretsen AH
        • Myklebust G
        • Holme I
        • Engebretsen L
        • Bahr R
        • et al.
        Prevention of injuries among male soccer players: a prospective, randomized intervention study targeting players with previous injuries or reduced function.
        Am J Sports Med. 2008; 36: 1052-1060https://doi.org/10.1177/0363546508314432
        View in Article
        • Gabbe BJ
        • Branson R
        • Bennell KL.
        A pilot randomised controlled trial of eccentric exercise to prevent hamstring injuries in community-level Australian Football.
        J Sci Med Sport. 2006; 9: 103-109https://doi.org/10.1016/j.jsams.2006.02.001
        View in Article
        • Guyatt GH
        • Oxman AD
        • Kunz R
        • Brozek J
        • Alonso-Coello P
        • Rind D
        • et al.
        GRADE guidelines 6. Rating the quality of evidence–imprecision.
        J Clin Epidemiol. 2011; 64: 1283-1293https://doi.org/10.1016/j.jclinepi.2011.01.012
        View in Article
        • Guyatt GH
        • Oxman AD
        • Kunz R
        • Woodcock J
        • Brozek J
        • Helfand M
        • et al.
        GRADE guidelines: 8. Rating the quality of evidence–indirectness.
        J Clin Epidemiol. 2011; 64: 1303-1310https://doi.org/10.1016/j.jclinepi.2011.04.014
        View in Article
        • Guyatt GH
        • Oxman AD
        • Kunz R
        • Woodcock J
        • Brozek J
        • Helfand M
        • et al.
        GRADE guidelines: 7. Rating the quality of evidence–inconsistency.
        J Clin Epidemiol. 2011; 64: 1294-1302https://doi.org/10.1016/j.jclinepi.2011.03.017
        View in Article
        • Petersen J
        • Thorborg K
        • Nielsen MB
        • Budtz-Jorgensen E
        • Holmich P
        • et al.
        Preventive effect of eccentric training on acute hamstring injuries in men’s soccer: a cluster-randomized controlled trial.
        Am J Sports Med. 2011; 39: 2296-2303https://doi.org/10.1177/0363546511419277
        View in Article
        • Sebelien C
        • Stiller C H
        • Maher S F
        • Qu X
        • et al.
        Effects of implementing Nordic hamstring exercises for semi-professional soccer players in Akershus, Norway.
        Ortopeadic Pract. 2014; 26: 90-97
        View in Article
        • Hasebe Y
        • Akasaka K
        • Otsudo T
        • Tachibana Y
        • Hall T
        • Yamamoto M
        • et al.
        Effects of nordic hamstring exercise on hamstring injuries in high school soccer players: a randomized controlled trial.
        Int J Sports Med. 2020; 41: 154-160https://doi.org/10.1055/a-1034-7854
        View in Article
        • van der Horst N
        • Smits DW
        • Petersen J
        • Goedhart EA
        • Backx FJ
        • et al.
        The preventive effect of the nordic hamstring exercise on hamstring injuries in amateur soccer players: a randomized controlled trial.
        Am J Sports Med. 2015; 43: 1316-1323https://doi.org/10.1177/0363546515574057
        View in Article

      Article info

      Publication history

      Published online: November 01, 2021
      Accepted: October 27, 2021

      Footnotes

      Conflict of interest: Both authors have previously published on the Nordic Hamstring exercise, and both work clinically and conduct research in different football settings.

      Identification

      DOI: https://doi.org/10.1016/j.jclinepi.2021.10.021

      Copyright

      © 2021 Elsevier Inc. All rights reserved.

      ScienceDirect

      Access this article on ScienceDirect
      We use cookies to help provide and enhance our service and tailor content. To update your cookie settings, please visit the for this site.
      Copyright © 2023 Elsevier Inc. except certain content provided by third parties. The content on this site is intended for healthcare professionals.


      RELX