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The Effect of an 8‐Week Low‐ or High‐Volume Protocol of the Adductor Strengthening Programme on Hip Adduction Strength in Female Football Players—A Randomized Trial

Authors:
Solveig Thorarinsdottir at Norwegian School of Sport Sciences
Solveig Thorarinsdottir
S. Isaksen Johansen
S. Isaksen Johansen
S. Isaksen Johansen
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T. Ruud Askim Elvestad
T. Ruud Askim Elvestad
T. Ruud Askim Elvestad
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Roar Amundsen at Norwegian School of Sport Sciences
Roar Amundsen
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Abstract and Figures

The aim of this study was to investigate if an 8‐week high‐volume protocol of the Adductor Strengthening Programme was more effective than a low‐volume protocol in increasing and maintaining isometric hip adduction strength in female football players. We randomized 52 players from the Norwegian women's 1st and 2nd division to a low‐volume (220 reps/side) or high‐volume (394 reps/side) group. Both groups performed an 8‐week protocol of the Adductor Strengthening Programme and a 10‐week maintenance protocol with 1 session/week (16 reps/side/session). We measured isometric hip adductor torque (Nm/kg) in a long‐lever squeeze test (at 0° and 15° hip abduction) using the ForceFrame at baseline, weeks 4, 6, 8, and 18. Both groups increased their isometric hip adduction strength over the 8‐week period (low‐volume 0°: 0.13 [95% CI: 0.07–0.20] Nm/kg, 15°: 0.22 [95% CI: 0.07–0.36] Nm/kg; high‐volume 0°: 0.13 [95% CI: 0.04–0.22] Nm/kg, 15°: 0.31 [95% CI: 0.18–0.45] Nm/kg), with no between‐group difference in either test position (0°: ‐0.01 [95% CI: −0.11‐0.01] Nm/kg; 15°: 0.10 [95% CI: −0.09‐0.29] Nm/kg). Also, both groups maintained their strength throughout the 10‐week maintenance period, with no between‐groups difference in either test position (0°: 0.12 [95% CI: −0.01‐0.24] Nm/kg; 15°: 0.06 [95% CI: −0.11‐0.23] Nm/kg). Our results indicate that an 8‐week high‐volume protocol of the Adductor Strengthening Programme was not more effective in increasing isometric adductor strength in female football players than a low‐volume protocol. Both groups increased their strength over the 8‐week training period and maintained their strength during the 10‐week maintenance period. Trial registration: The study protocol was uploaded to Open Science Framework before unblinding and analyzing the data (https://osf.io/7xfw4/)
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Scandinavian Journal of Medicine & Science in Sports, 2025; 35:e70039
https://doi.org/10.1111/sms.70039
Scandinavian Journal of Medicine & Science in Sports
ORIGINAL ARTICLE
The Effect of an 8- Week Low- or High- Volume Protocol of
the Adductor Strengthening Programme on Hip Adduction
Strength in Female Football Players—A Randomized Trial
S.Thorarinsdottir1 | S.IsaksenJohansen2 | T.RuudAskimElvestad2 | R.Amundsen1 | L.K.Bache-Mathiesen1,3 |
R.Bahr1 | M.Møller1,4
1Oslo Sports Trauma Research Center, Department of Sports Medicine, Norwegian School of Sports Sciences, Oslo, Norway | 2Department of Sports
Medicine, Nor wegian School of Sport Sciences, Oslo, Nor way | 3Department of Behavioural Medicine, University of Oslo, Olso, Norway | 4Research
Unit of Musculoskeletal Function and Physiotherapy, Department of Sports Science and Clinical Biomechanics, University of Southern Denmark,
Sonderborg,Denmark
Correspondence: S. Thorarinsdottir (solveigt@nih.no)
Received: 27 November 2024 | Revised: 6 March 2025 | Accepted: 10 March 2025
Funding: The Oslo Sports Trauma Research Center receives grants from the Royal Norwegian Ministr y of Culture, the South- Eastern Nor way Regional
Health Authority, the International Olympic Committee, the Nor wegian Olympic Committee and Confederation of Sport , and Norsk Tipping AS.
Keywords: adductor strengthening| Copenhagen adduction exercise| football| groin| women
ABSTRACT
The aim of this study was to investigate if an 8- week high- volume protocol of the Adductor Strengthening Programme was more
effective than a low- volume protocol in increasing and maintaining isometric hip adduction strength in female football players.
We randomized 52 players from the Norwegian women's 1st and 2nd division to a low- volume (220 reps/side) or high- volume
(394 reps/side) group. Both groups performed an 8- week protocol of the Adductor Strengthening Programme and a 10- week
maintenance protocol with 1 session/week (16 reps/side/session). We measured isometric hip adductor torque (Nm/kg) in a long-
lever squeeze test (at 0° and 15° hip abduction) using the ForceFrame at baseline, weeks 4, 6, 8, and 18. Both groups increased
their isometric hip adduction strength over the 8- week period (low- volume 0°: 0.13 [95% CI: 0.07–0.20] Nm/kg, 15°: 0.22 [95%
CI: 0.07–0.36] Nm/kg; high- volume 0°: 0.13 [95% CI: 0.04–0.22] Nm/kg, 15°: 0.31 [95% CI: 0.18–0.45] Nm/kg), with no between-
group difference in either test position (0°: - 0.01 [95% CI: −0.11- 0.01] Nm/kg; 15°: 0.10 [95% CI: −0.09- 0.29] Nm/kg). Also, both
groups maintained their strength throughout the 10- week maintenance period, with no between- groups difference in either test
position (0°: 0.12 [95% CI: −0.01- 0.24] Nm/kg; 15°: 0.06 [95% CI: −0.11- 0.23] Nm/kg). Our results indicate that an 8- week high-
volume protocol of the Adductor Strengthening Programme was not more effective in increasing isometric adductor strength in
female football players than a low- volume protocol. Both groups increased their strength over the 8- week training period and
maintained their strength during the 10- week maintenance period.
Trial registration: The study protocol was uploaded to Open Science Framework before unblinding and analyzing the data
(https:// osf. io/ 7xfw4/ )
1 | Introduction
Groin injuries are frequent in football and other sports involving
rapid changes of direction, acceleration, and kicking [1, 2]. In
women's professional football, groin injuries represent up to 16% of
all time- loss injuries [3–8] and, like in men's football, most often af-
fect the adductors [9]. These findings underscore the need for strat-
egies to minimize the risk of groin injuries in women's football.
© 2025 Joh n Wiley & Sons A/S. P ublished by John Wi ley & Sons Ltd.
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Groin injuries in women's premier league football in Norway: A two‐season prospective cohort study describing clinical and imaging characteristics
Article
Full-text available
  • Mar 2024
  • SCAND J MED SCI SPOR
Objective To describe the prevalence, incidence, and burden of groin injuries in the Norwegian women's premier football league and to describe their clinical and imaging characteristics. Methods During the 2020 and 2021 seasons, players in the Norwegian women's premier league reported groin injuries weekly, using the Oslo Sports Trauma Research Centre Questionnaire on Health Problems (OSTRC‐H2). We calculated weekly prevalence, incidence, and burden of groin injuries. The team physical therapists classified the player‐reported injuries based on the Doha classification system. Injuries with more than 3 days' time loss or reported in 2 consecutive weeks were eligible for magnetic resonance imaging (MRI). Results On average, 3.9% (95% CI: 3.4–4.4) of players reported a groin injury at any time; of which 78% caused time loss. The incidence rate was 1.6 injuries/1000 h (95% CI: 1.3–2.0) and their burden was 11 days lost/1000 h. The physical therapists examined 67 of 124 player‐reported groin injuries (53%). Adductor‐related injury was most common (55%) followed by iliopsoas (15%) and rectus femoris‐related (12%). Pubic‐related injuries caused most time loss (median: 24 days, IQR: 5–133). In this study, 42 injuries were investigated with MRI; 8 (19%) showed no changes, 6 (14%) an acute musculotendinous lesion, and 32 (76%) a nonacute finding (e.g., central symphyseal disc protrusion, tendinopathies). Conclusion The incidence rate and burden of groin injuries were high. Adductor‐related injuries were most common, but pubic‐related injuries caused most time loss. Most MRI examinations demonstrated nonacute findings.
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The evidence-based hamstring strengthening programme for prevention of hamstring injuries is not adopted by football teams because of its high training volume. This study on female football players investigated if high-volume training with the Nordic hamstring exercise is more effective on hamstring strength, jump height, and sprint performance than low-volume training. We also examined the time course of changes in muscle strength during the intervention period. Forty-five female football players were randomised to a high- (21 sessions, 538 total reps) or low-volume group (10 sessions, 144 total reps) and performed an 8-week training intervention with the Nordic hamstring exercise during the preseason. We tested hamstring strength (maximal eccentric force with NordBord and maximal eccentric torque with isokinetic dynamometer), jump height, and 40 m sprint before and after the intervention. The NordBord test was also performed during training weeks 4 and 6. Both groups increased maximal eccentric force (high-volume: 29 N (10%), 95% CI: 19–38 N, p < 0.001 , low-volume: 37 N (13%), 95% CI: 18–55 N, p = 0.001 ), but there were no between-group differences ( p = 0.38 ). Maximal eccentric torque, jump height, and sprint performance did not change. Maximal eccentric force increased from the pretest to week 6 (20 N (7%), 95% CI: 8 to 31 N, p < 0.001 ), but not week 4 (8 N (3%), 95% CI: −2 to 18 N, p = 0.22 ). High training volume with the Nordic hamstrings exercise did not lead to greater adaptations in strength, jump height, or speed than a low-volume programme. Players in both groups had to train for at least 6 weeks to improve maximal eccentric force significantly.
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Several aspects of systemic alterations caused by the SARS-CoV-2 virus and the resultant COVID-19 disease have been currently explored in the general population. However, very little is known about these particular aspects in sportsmen and sportswomen. We believe that the most important element to take into account is the neuromuscular aspect, due to the implications that this system entails in motion execution and coordination. In this context, deficient neuromuscular control when performing dynamic actions can be an important risk factor for injury. Therefore, data in this review refer mainly to problems derived in the short term from athletes who have suffered this pathology, taking into account that COVID-19 is a very new disease and the presented data are still not conclusive. The review addresses two key aspects: performance alteration and the return to regular professional physical activity. COVID-19 causes metabolic-respiratory, muscular, cardiac, and neurological alterations that are accompanied by a situation of stress. All of these have a clear influence on performance but at the same time in the strategy of returning to optimal conditions to train and compete again after infection. From the clinical evidence, the resumption of physical training and sports activity should be carried out progressively, both in terms of time and intensity.
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The Effects of Eccentric Strength Training on Flexibility and Strength in Healthy Samples and Laboratory Settings: A Systematic Review
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Background: The risk of future injury appears to be influenced by agonist fascicle length (FL), joint range of motion (ROM) and eccentric strength. Biomechanical observations of the torque-angle-relationship further reveal a strong dependence on these factors. In practice, a longer FL improves sprinting performance and lowers injury risk. Classical stretching is a popular and evidenced-based training for enhancing ROM but does not have any effects on FL and injury risk. However, recent studies show that eccentric-only training (ECC) improves both flexibility and strength, and effectively lowers risk of injury. Objectives: To review the evidence on benefits of ECC for flexibility and strength. Methods: COCHRANE, PUBMED, SCOPUS, SPOLIT, and SPONET were searched for laboratory trials that compare ECC to at least one comparison group. Studies were eligible if they examined both strength and flexibility metrics in a healthy sample (<65 years) and met criteria for controlled or randomized clinical trials (CCT, RCT). 18 studies have been included and successfully rated using the PEDro scale. Results: 16 of 18 studies show strong evidence of strength and flexibility enhancements for the lower limb. While improvements between ECC and concentric training (CONC) were similar for eccentric (+19 ± 10% vs. +19 ± 11%) and isometric strength (+16 ± 10% vs. +13 ± 6%), CONC showed larger improvements for concentric strength (+9 ± 6% vs. +16 ± 7%). While for ROM ECC showed improvements (+9 ± 7%), no results could be found for CONC. The overall effectiveness of ECC seems to be higher than of CONC. Conclusion: There is clear evidence that ECC is an effective method for changes in muscle architecture, leading to both flexibility and strength improvements for the lower limb. Due to limited data no shoulder study could be included. Further research is needed for the upper body joints with a focus on functional and structural adaptions. Systematic Review Registration: https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42021283248, identifier CRD42021283248
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Reliability of hip muscle strength measured in principal and intermediate planes of movement
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Background Muscle strength testing is widely used in clinical and athletic populations. Commercially available dynamometers are designed to assess strength in three principal planes (sagittal, transverse, frontal). However, the anatomy of the hip suggests muscles may only be recruited submaximally during tasks performed in these principal planes. Objective To evaluate the inter-session reliability of maximal isometric hip strength in the principal planes and three intermediate planes. Methods Twenty participants (26.1 ± 2.7 years, 50% female) attended two testing sessions 6.2 ± 1.8 days apart. Participants completed 3-5 maximal voluntary isometric contractions for hip abduction, adduction, flexion, extension, and internal and external rotation measured using a fixed uniaxial load cell (custom rig) and commercial dynamometer (Biodex). Three intermediate hip actions were also tested using the custom rig: extension with abduction, extension with external rotation, and extension with both abduction and external rotation. Results Moderate-to-excellent intraclass correlation coefficients were observed for all principal and intermediate muscle actions using the custom rig (0.72–0.95) and the Biodex (0.85–0.95). The minimum detectable change was also similar between devices (custom rig = 11–31%; Biodex = 9–20%). Bland-Altman analysis revealed poor agreement between devices (range between upper and lower limits of agreement = 77–131%). Conclusions Although the custom rig and Biodex showed similar reliability, both devices may lack the sensitivity to detect small changes in hip strength commonly observed following intervention.
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Effects of a low‐dose Copenhagen Adduction exercise intervention on adduction strength in sub‐elite male footballers: a randomised controlled trial
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Footballers with weak hip adductors are at increased risk of groin injury and adductor strengthening has been shown to reduce this risk. However, the minimal effective dose of strength training to improve hip‐adductor strength and mitigate the risk of adductor problems remains unknown. The aim of this randomised controlled trial was to investigate the training and detraining effects of a low‐dose Copenhagen adduction exercise (CA) intervention in sub‐elite male footballers on eccentric hip‐adduction strength (primary outcome) and peak adductor squeeze strength (secondary outcome). Thirty‐nine male footballers were randomised into two groups: the intervention group completed the CA twice weekly during six in‐season weeks in addition to normal football training, while the control group continued normal football training. Strength testing was performed at weeks 0, 3, 6 (training period), and weeks 7‐9 (detraining period). There was no between‐group difference in eccentric strength at week 6 and 9. There was a significant group‐by‐time interaction at 6 weeks (0.52 Nm/kg, 95% CI 0.17‐0.86) and 9 weeks (0.59 Nm/kg, 95% CI 0.25‐0.93) at which the intervention group displayed greater adductor squeeze strength. These results suggest the low‐dose CA intervention is insufficient to modify eccentric hip‐adduction strength but improves peak adductor squeeze strength.
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The aim of this study was to compare male vs. female athletes in strength and power performance relative to body mass (BM) and lean body mass (LBM) and to investigate the relationships between muscle architecture and strength in both genders. Sixteen men (age = 26.4 ± 5.0 y; body mass = 88.9 ± 16.6 kg; height = 177.6 ± 9.3 cm) and fourteen women (age = 25.1 ± 3.2 y; body mass = 58.1 ± 9.1 kg; height = 161.7 ± 4.8 cm) were tested for body composition and muscle thickness (MT) of vastus lateralis muscle (VT), pectoralis major (PEC), and trapezius (TRAP). In addition, participants were tested for lower body power at countermovement jump (CMJP) and upper-body power at bench press throw (BPT). Participants were also assessed for one repetition maximum (1RM) at bench press (1RMBP), deadlift (1RMDE), and squat (1RMSQ). Significantly greater (p < 0.01) MT of the VL, PEC and TRAP muscles and LBM were detected in men compared to women. Significantly greater (p < 0.05) 1RMBP and BPT adjusted for LBM were detected in men than in women. No significant gender differences after adjusting for LBM were detected for 1RMSQ (p = 0.945); 1RMDE (p = 0.472) and CMJP (p = 0.656). Significantly greater (p < 0.05) results in all performance assessments adjusted for MT of the specific muscles, were detected in males compared to females. Superior performances adjusted for MT and LBM in men compared to women, may be related to gender differences in muscle morphology and LBM distribution, respectively.
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Past-season, pre-season and in-season risk assessment of groin problems in male football players: A prospective full-season study
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  • Mar 2021
Objective We assessed past-season, pre-season and in-season risk factors to investigate their association with an in-season groin problem in male amateur football players. Methods Past-season groin-pain information and pre-season short-lever and long-lever adductor squeeze strength were obtained at baseline, together with anthropometrics (weight, lower limb lever length) and player age. In-season hip-related and groin-related sporting function was monitored every 4 weeks using the Sports and Recreation (Sport) subscale from the Hip And Groin Outcome Score questionnaire (HAGOS (Sport)). Groin problems, including time-loss groin injuries and groin pain irrespective of time loss, were collected over a 39-week competitive in-season. We estimated relative risk (RR), and 95% credibility interval (ICr) from logistic regressions fitted in a Bayesian framework. Results Players (n=245) suffering from groin pain during the past-season had 2.4 times higher risk of experiencing a groin problem in the new season (2.40 RR; 95% ICr 1.5 to 3.7). This risk was reduced by 35% (0.65 RR; 95% ICr 0.42 to 0.99) per unit (N·m/kg) increase in the long-lever adductor squeeze test. Player age, short-lever squeeze test and the HAGOS (Sport) scores were not associated with the risk of a groin problem. Conclusions Past-season groin pain increased the risk of a groin problem in the new in-season. This risk was reduced by higher pre-season long-lever adductor squeeze strength. Past-season groin-pain information and long-lever adductor squeeze strength can be quickly obtained during pre-season to identify players with an elevated risk of in-season groin problems. This may be key to reduce these problems in the new season.
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