The use of eccentric quadriceps training has gained much traction in the treatment of patella tendinopathy (Purdam et al, 2004; Jonsson and Alfredson, 2005). However, eccentric training programmes have not shown promising results in all athletes and it has also been proven to be painful (Visnes et al, 2005). Alternative research with regards to combined exercise programmes have shown promising results, but its methods are largely varied and so a lack of consensus still exists concerning the most appropriate form of exercise and its effect on patella tendinopathy. A literature review of eight studies was carried out.
These studies used a variety of eccentric, concentric and combined eccentric and concentric exercises, outcome measures and comparison groups. Most studies revealed that a 12 week eccentric training programme was beneficial, and a four week combined programme was beneficial. However, due to a number of disparities between these studies, their results can only be considered independently of each other and a conclusive comment cannot be made on its effectiveness. Thus, the proposed study aims to investigate the effectiveness of eccentric versus combined eccentric and concentric strength training in the management of chronic patella tendinopathy.
1.2 IntroductionPatella tendinopathy or Jumper’s Knee is an overuse injury, characterised by pain and dysfunction in the patellae tendon (Rudavsky and Cook, 2014). Pain occurs during activities requiring high level tendon loading, such as jumping and changing direction (Rudavsky and Cook, 2014).
Symptomatic patella tendinopathy is most prevalent in the athletic population, with highest incidence in both elite and non-elite volleyball players. (Zwerver, Bredeweg and van den Akker-Scheek, 2011; Lian, Engebretsen and Bahr, 2005). Research into the pathophysiology behind tendon pain found that there was significantly higher amounts of the excitatory neurotransmitter, glutamate, found in tendons with tendonitis compared to normal tendons (Alfredson, 2005).
Alternatively, Lian et al, (2007) found that increased apoptotic cell death was associated with patella tendons with overuse injury. However, precise pathophysiology behind patella tendon overuse injuries is still undefined and requires further research (Alfredsson et al, 2003). Many different types of conservative physiotherapy managements have been proposed to treat patella tendinopathy such as strengthening programmes (Almekinders et al. 1993), ultrasound (Ramirez et al. 1997) and friction (Gehlsen et al. 1999). Eccentric strengthening programmes have shown good clinical results in patellar tendinopathy (Purdam et al, 2004; Jonsson and Alfredson, 2005; Frohm et al, 2007).
However eccentric exercises were also found to be painful, especially in in-season athletes (Purdam et al, 2004; Visnes et al, 2005). Conversely, isometric exercises have been found to decrease tendon pain immediately post-intervention (Rio et al, 2015). Several papers have also studied the effectiveness of combined eccentric and concentric exercises (Jonsson and Alfredson, 2005; Romero-Rodriguez, Gual and Tesch, 2011; Ark, et al, 2015). However they have largely varied approaches and methods. Due to the wide range of treatment methods and variables used there still exists a deficiency in knowledge regarding the best type of strength training programme, and a conclusive result with regards to best treatment cannot be drawn. Hence, this literature review aims to investigate the effect of eccentric, concentric and combined strength training on patellar tendinopathy. 1.
3 OverviewThe electronic databases of PEDro, Pubmed and Google Scholar were used to source for relevant studies in November, 2017, using the keywords: Patella tendinopathy, Jumper’s knee, eccentric training, concentric training, pain, function. From the studies found and screened, eight were analysed for this review. Five investigated the effects of eccentric quadriceps training on subjects with patella tendinopathy (Purdam et al, 2004; Frohm et al, 2007; Jonsson and Alfredson, 2005; Visnes et al, 2005; Dimitrios, Pantelis and Kalliopi, 2011), while four investigated the effect of combined eccentric and concentric training on patella tendinopathy (Cannell et al, 2001; Kongsgaard et al, 2009; Romero-Rodriguez, Gual and Tesch, 2011; Ark, et al, 2015). Seven of these studies were randomised control trials (Frohm et al, 2007; Jonsson and Alfredson, 2005; Visnes et al, 2005; Cannell et al,2001; Kongsgaard et al,2009; Ark, et al,2015) while one was a case-series study (Romero-Rodriguez, Gual and Tesch, 2011).The studies included subjects diagnosed with patella tendinopathy but were otherwise healthy (no other knee-related co-morbidities or history of knee surgery).
The number of subjects recruited ranged from ten to 39, with duration of symptoms totalling two months (Romero-Rodriguez, Gual and Tesch, 2011), or three months or more. Three studies specifically looked at subjects participating in training or competition at the time of the study (Visnes et al, 2005; Romero-Rodriguez, Gual and Tesch, 2011; Ark, et al, 2015).Six studies used a 12-week intervention period, one study used a six-week intervention period (Romero-Rodriguez, Gual and Tesch, 2011) and two a four-week intervention period (Ark, et al, 2015; Dimitrios, Pantelis and Kalliopi, 2011).
All studies except three (Visnes et al, 2005; Ark, et al, 2015; Dimitrios, Pantelis and Kalliopi, 2011) had a 12-week follow-up period. Two had a six-month follow-up period (Kongsgaard et al, 2009; Dimitrios, Pantelis and Kalliopi, 2011). Six studies used standard or declined drop squats for eccentric training while four studies also used combined eccentric and concentric strengthening protocol (using leg press) as comparison (Cannell et al, 2001; Kongsgaard et al, 2009; Romero-Rodriguez, Gual and Tesch, 2011; Ark, et al, 2015). Throughout the studies, eccentric quadriceps training was compared with usual training (Visnes et al, 2005), concentric training (Jonsson and Alfredson, 2005), eccentric training of a different protocol (Frohm et al, 2007), eccentric decline squats (Purdam et al,2004), leg extension/leg curl exercises (Cannell et al, 2001), eccentric training with static stretching (Dimitrios, Pantelis and Kalliopi, 2011) and, corticosteroid injection and heavy slow resistance training (HSR) (Kongsgaard et al, 2009). One study had a pre- and post-test measurement design, evaluating effectiveness of a combined eccentric and concentric resistance training programme (Romero-Rodriguez, Gual and Tesch, 2011) and one study compared isometric with isotonic training protocol (Ark, et al, 2015).
1.3.1 Outcome measuresVarious outcome measures were utilised throughout the six studies. Pain was the main outcome measure used. The Visual Analogue Scale (VAS) (Purdam et al, 2004; Frohm et al, 2007; Jonsson and Alfredson, 2005; Cannell et al, 2001; Kongsgaard et al, 2009; Romero-Rodriguez, Gual and Tesch, 2011) and Numerical Rating Scale (NRS) (Ark et al, 2015) were used to measure pain. Other outcome measures such as the Victorian Institute of Sport Assessment Questionnaire, Patellar Tendon (VISA-P), range of motion (ROM), Biodex dynamometers to measure quadriceps strength, functional tests, patient satisfaction and return to sport. 1.3.
2 PainAn overall decrease in pain was reported for moat subjects who underwent eccentric quadriceps training, while mixed results were gathered for concentric training. Purdam et al, (2014) reported a significant drop in mean VAS score from 74.2 to 28.5 (p=0.
004) in subjects who underwent decline squats protocol, but no significant change was reported for the standard squat group. According to Frohm et al, (2007), two different eccentric training protocols both yielded significant improvements in VAS score (p,0.001 for each group), with no significant difference between groups.
Dimitrios, Pantelis and Kalliopi, (2011) found that eccentric training with static stretching induced significant increase in VISA-P score (P<0.005) after 4 weeks, and the magnitude of improvement was significantly larger than just eccentric training. Jonsson and Alfredson, (2005) reported that an eccentric training protocol resulted in significant decrease in VAS score from 73 to 23 (p,0.005), but not for concentric training where VAS score decreased from 74 to 68, (p,0.
34). Cannell et al, (2001) compared the effectiveness of drop squats versus concentric leg exercises and found that over the 12 week intervention there was a signi?cant main effect for pain reduction in both groups (p<0.01). Romero-Rodriguez, Gual and Tesch, (2011) found that VAS decreased by 60% (p < 0.
01) after coupled concentric and eccentric actions on a leg press device. Ark et al, (2015) reported that pain improved significantly within both the isometric group (Z = ?2.527, p = 0.012) and isotonic group (Z = ?2.952, p = 0.
003), with no significant difference between groups (p = 0.208). Kongsgaard et al, (2009) found that pain improved significantly after 12 weeks for all three groups, but only HSR showed significant decrease in pain after long-term follow-up.
1.3.3 Functional abilityThere was a significant improvement in VISA- P score for most subjects who underwent eccentric (Purdam et al, 2004; Frohm et al, 2007; Jonsson and Alfredson, 2005; Cannell et al, 2001; Dimitrios, Pantelis and Kalliopi, 2011) or combined (Romero-Rodriguez, Gual and Tesch, 2011; Ark, et al, 2015; Cannell et al, 2001) training, and no significant improvement in VISA-P score with only concentric training (Jonsson and Alfredson, 2005).
Visnes et al, (2005) reported no significant improvement in VISA-P score after 12 weeks of eccentric decline squats training. 1.3.4 StrengthStrength was only evaluated in three studies. Over the 12-week intervention, Cannell et al, (2001) reported no signi?cant increase in quadriceps strength over in either the concentric or eccentric group. A significant rise in extensor torque was reported after treatment for both legs in both eccentric training protocol groups in the study by Frohm et al, (2007). According to Romero-Rodriguez, Gual and Tesch, (2011), maximal eccentric force increased (90%, p=0.003) after combined eccentric and concentric training.
1.4 Discussion The earliest study by Cannell et al, (2001) was the first randomised control trial examining the effectiveness of eccentric and concentric exercises to treat patella tendinopathy. It found that there was no significant difference between drop squats or leg extension/leg curl exercises and both groups yielded significant improvement in pain. The study recruited patients from a variety of sports backgrounds, making their results generalizable to majority of the athletic population. However, only pain was used as a diagnosing criteria for patella tendinopathy and no scans were conducted to confirm the diagnosis. Although this study provided a detailed description of its exercise programmes, it did not provide a scientific reasoning for each variable. A 12-week intervention period was used from clinical experience and other variables were adopted from previous uncontrolled trials.
This study also used a co-intervention (running) for both groups, which could have contaminated the effects of the main intervention. Anti-inflammatory medication was also used by subjects in the first two weeks of the intervention, which could have masked the effects of the main intervention. Purdam et al.
(2004) conducted a study to investigate the effectiveness of decline squats as opposed to squats in a standard ankle position and found that decline squats yielded favourable results in terms of pain improvement and return to sport. However, these results should be guardedly analysed as the study was not randomised and baseline gender distribution and age may have had a significant difference between groups. Although their exercise programme was described in detail, and choice of exercise was explained with a physiological basis, choice of exercise variables (sets and reps) was not explained scientifically, nor was it stated if the variables were adopted from experience or previous trials. Furthermore, no functional outcome measure specific to patella tendinopathy was used.
Patients were also treated with non-steroidal anti-inflammatory drugs and one patient (group unknown) was given a hydrocortisone injection prior to the study and these could have contaminated the effects of the main intervention. Adding to the above study, Jonsson and Alfredson, (2005) compared painful eccentric declines squats with painful concentric decline squats in athletes with patella tendinopathy. After using similar programme variables as Purdam et al, (2004), they found that painful eccentric training reduced pain and improved function significantly but concentric training did not. Subjects in this study came from various sports backgrounds, making their results generalizable to a wider range of athletes. However, according to power analysis, this study’s sample size was too small to detect a difference in the results of the treatments at the 0.05 significance level, which reduces the accuracy of the results. Furthermore, the same programme variables as Purdam et al, (2004) were used for eccentric decline squats due to its success, however the same variables may not have been ideal for concentric decline squats. Scientifically established programme variables for concentric training could have improved this study.
Visnes et al, (2005) conducted a study to explore the effectiveness of eccentric decline squats training as opposed to usual training in volleyball players during competitive season, using the same programme variables as the earlier studies. They found that there was no significant effect on VISA-P scores after the 12-week intervention. This was a well-designed randomised controlled trial. It had a larger sample size than most other studies and did not include any co-interventions. Subjects were also made to documents their training sessions and activity levels. However the intervention was a home-based programme and there was no direct supervision by a physiotherapist.
Additionally, the training group only completed 59% of the recommended volume of exercise and this may not have been sufficient to yield significant results. A study by Frohm et al, (2007) was conducted to compare the effectiveness of two different eccentric training protocols. It was found that two-legged eccentric overload training using the Bromsman device was more effective than one-legged declined squats. This study includes several co-interventions such as trunk and foot stability training, and resumption of jogging and plyometric training in the last six week of the intervention period. These co-interventions may contaminate the effects of the main intervention being investigated and distort the results. Building on the previous studies by Purdam et al, (2004) and Jonsson and Alfredson, (2005), Kongsgaard et al, (2009) attempted to compare the effects of the popular eccentric decline squat training with peritendinous corticosteroid injections and heavy slow resistance training (combination of eccentric and concentric training).
They found that HSR caused significant improvement in pain and VISA-P score both in the short-term and in long-term follow-up. Reductions of tendon abnormality was an added finding after HSR. This was a well-designed single-blinded randomised control trial with a comparative design. However this study is limited by its small sample size, which prevents drawing of a firm conclusion about the difference between eccentric training and HSR. Romero-Rodriguez, Gual and Tesch, (2011) conducted a study aimed at determining the effect of couple eccentric-concentric muscle action through inertial eccentric overload training on patella tendinopathy.
They found that short-term training decreased pain and improved muscle function. However this was a case-series study and not a randomised controlled trial. Furthermore, there was no control group for comparison, so it cannot be said that changes to pain and function was a direct result of the intervention. Albeit it was noted that on follow-up, there were no changes to the results post-intervention. Additionally, only five out of ten subjects continued their own training during the intervention period. This could have affected the consistency of the intervention and confounded the results of the study. Dimitrios, Pantelis and Kalliopi, (2011) conducted a study investigating the effects of eccentric training and eccentric training with static stretching exercises in non-athletes with patella tendinopathy.
They found that eccentric training with static stretching yielded the highest effect at the end of four weeks and at the six-month follow-up. This study had an advantage over the others formerly reviewed, in that no co-interventions such as anti-inflammatory drugs were used, hence the effects of the main intervention were not diluted. Furthermore, use of a treatment diary by the subjects allowed patient compliance to be monitored.
However a flaw in this study is that it did not use randomised allocation and instead, sequential, alternate allocation was used instead. This could have diminished the internal validity of this study. Ark, et al, (2015) conducted a study to investigate the effects of isometric and isotonic exercises on in-season jumper’s knee. They found that both isometric and isotonic exercises resulted in a significant improvement in pain and VISA-P score after a four-week intervention period. This was a well-designed randomised controlled trial. However there were several limitations in this study. Firstly, they failed to describe the patients’ underlying diagnosis sufficiently and only pain was used as an inclusion criteria.
Secondly, the exercises were unsupervised, hence compliance and accuracy of the interventions performed were not monitored. 1.5 ConclusionNo conclusive deduction can be made with regards to the effect of eccentric, concentric and combined quadriceps training on pain and function in subjects with patella tendinopathy. A number of different strengthening programmes, outcome measures, co-interventions and comparison groups were employed in the eight studies reviewed. Due to multiple disparities between these studies, their results can only be considered independently of each other and a conclusive comment cannot be made on its effectiveness overall.
All in all, the results of the studies did indicate that a 12-week eccentric training programme or a four week combined training programme had a positive outcome on pain and function, while concentric training alone was detrimental. However, these studies varied largely and various co-interventions were also used, diluting the effects of the main interventions being studied. Further research is needed to investigate the effects of eccentric, concentric and combined strength training on pain and function in patients with patella tendinopathy. Research is required specifically to examine the effects of a combined eccentric and concentric quadriceps training programme in comparison with the traditional eccentric exercise, with the exclusion of co-interventions.