Section 1: Literature Review- “The role of eccentric calf-muscle training in the management of chronic Achilles tendinopathy”

1.1 Abstract

Eccentric calf-muscle training has become a popular choice for the treatment of chronic Achilles tendinopathy and it is becoming increasingly recognised as a potential gold-standard for the management of this condition (Chester et al., 2007). However, a lack of knowledge still exists regarding the most appropriate form of treatment and the benefit of eccentric calf-muscle training for the pain and functional ability associated with chronic Achilles tendinopathy remains unclear.

A systematic review of the literature was carried out. Eight studies were reviewed; these used a couple of eccentric training programmes, various outcome measures and different comparison groups. Studies revealed improvements in participants’ pain and functional ability after a 12-week training programme. These results would suggest that eccentric calf-muscle training does have a beneficial effect. However, with a wide variation between the studies, they could only be assessed individually and the extent of the benefit could not be definitively established.

1.2 Introduction

Achilles tendinopathy is a chronic condition, usually characterised by degeneration of the Achilles tendon, known as Achilles tendinosis. It is a breakdown of the Achilles tendon with small, focal lesions within the tendon, without an inflammatory response (PhysioRoom, 2007).

Achilles tendinopathy occurs in men and women of all ages but especially in middle-aged men (Cook et al., 2002). Achilles tendon disorders are considered to be one of the most common overuse injuries in elite and recreational athletes (Jozsa et al., 1997; Soma et al., 1994). And 6 – 18% of all injuries in recreational runners involve the Achilles tendon (Schepsis et al., 2002).

However, Achilles tendinopathy is not always associated with physical activity and sedentary individuals may also experience the condition (Kader et al., 2002). Recent studies have shown that 33% of patients with chronic Achilles tendinopathy are not physically active. They also show that physical activity does not correlate with histopathological findings of the Achilles tendon (Alfredson et al., 2003; Astrom et al., 1998).

Little scientific evidence is available for most conservative treatments used for chronic painful conditions in the Achilles tendon – treatments such as ultrasound, deep frictional massage, night splint and concentric/eccentric calf-muscle training. The lack of evidence surrounding these treatments raises questions regarding the treatment of choice for patients with Achilles tendinopathy.

Stanish et al., (1986) proposed a theory which suggested that eccentric muscle strength training should be included in the rehabilitation of tendon injuries and they showed promising results with an eccentric training model in patients with chronic tendinitis. An eccentric muscle contraction occurs when a muscle lengthens because it is being stretched by an external force while contracting (Sherwood, 2004). Since Stanish et al., (1986) first proposed this theory, eccentric calf-muscle training has become a popular treatment choice and is becoming increasingly recognised as a potential gold standard for the management of chronic Achilles tendinopathy (Chester et al., 2007).

However, despite this claim, a general lack of knowledge still exists regarding the most appropriate form of treatment. This review investigated the use of eccentric calf-muscle training as a conservative form of treatment. Firstly, it investigated whether this treatment was appropriate for the management of pain associated with chronic Achilles tendinopathy. Secondly, as Achilles tendinopathy is often a disabling condition (Kader et al., 2002), the review sought to determine the effect of the treatment on the functional ability of patients.

1.3 Overview

The electronic databases of Pub Med, Medline and Google Scholar were searched in November 2007 using the following words in various compositions: Achilles tendon, tendinopathy, tendinosis, eccentric training, calf-muscle, physiotherapy, pain, chronic, function. Studies found were screened and eight were examined for this review; all of these investigated the effect of eccentric calf-muscle training on participants with chronic Achilles tendinopathy. Six of these studies were randomised, controlled trials (Mafi et al., 2001; Roos et al., 2004; Silbernagel et al., 2001; Herrington et al., 2007; de Vos et al., 2007; Chester et al., 2007), and two were controlled trials (Alfredson et al., 1998; Fahlstrom et al., 2003).

The studies included patients with diagnosed Achilles tendinopathy and three of them specifically looked at patients who had active participation in a sporting activity (Alfredson et al., 1998; Fahlstrom et al., 2003; de Vos et al., 2007). The participant numbers varied from 15 to 108 and the duration of symptoms varied from >2 months to 25 months.

Alfredson eccentric calf-muscle training model was used in six of the studies (Alfredson et al., 1998; Mafi et al., 2001; Fahlstrom et al., 2003; Roos et al., 2004; de Vos et al., 2007; Herrington et al., 2007); and all of them used a 12-week treatment period. The follow-up period varied from a number of weeks to a year (see Appendix D).

Throughout the studies, eccentric calf-muscle training was compared with concentric training (Mafi et al., 2001), eccentric training at a lower intensity (Silbernagel et al., 2001), surgical intervention (Alfredson et al., 1998), a night splint (de Vos et al., 2007; Roos et al., 2004), combined with a night splint (Roos et al., 2004), with ultrasound (Chester et al., 2007), deep frictional massage (Herrington et al., 2007) and stretching (Herrington et al., 2007). One study just compared eccentric calf-muscle training on patients with mid-portion and insertional Achilles tendon pain (Fahlstrom et al., 2003).

1.3.1 Outcome Measures

The eight studies used various outcome measures (see Appendix D). The pain was the primary outcome measure. This was measured using the Visual Analogue Scale (VAS) (Alfredson et al., 1998; Mafi et al., 2001; Fahlstrom et al., 2003; Chester et al., 2007) and pain on palpation (Silbernagel et al., 2001). Pain during Achilles tendon loading activities was measured in five studies (Alfredson et al., 1998; Mafi et al., 2001; Fahlstrom et al., 2003; Silbernagel et al., 2001; Chester et al., 2007). Other outcome measures used were physical activity levels, Victoria Institute of Sports Assessment-Achilles (VISA-A) questionnaire, Foot and Ankle Outcome Score (FAOS) questionnaire, Functional Index of Leg and Lower Limb (FILLA) questionnaire, patient satisfaction scales, ankle range of movement (ROM), calf-muscle strength and a number of functional tests (e.g. toe-raises, jumping).

1.3.2 Pain

A reduction in pain levels of participants treated with eccentric calf-muscle training was reported in all studies. Alfredson et al., (1998) and Mafi et al., (2001) showed significant decreases in VAS scores from ~ 81.2 to ~ 4.8 (P<0.001) and ~ 69 to ~ 12 (P<0.002) respectively over the 12 weeks. A significant decrease in VAS from ~ 66.8 to ~ 10.2 (P<0.001) was seen for the mid-portion participants in the study by Fahlstrom et al., (2003). However, this was not seen in the group with insertional Achilles tendon pain whereby only 31% of participants showed a significant decrease of pain during activity from ~ 68.3 to ~ 13.3 (P<0.01). Roos et al., (2004) used the FAOS to evaluate pain; the eccentric group in this study reported significant reductions in pain of 27% after 6 weeks (P=0.007) and 42% after 1 year (P=0.001). Silbernagel et al., (2001) showed that the eccentric group had a significant decrease in pain on palpation at 3 and 6 months after treatment (P<0.05). Chester et al., (2007) showed some improvement in VAS at 6 weeks but, overall, showed no significant changes in VAS after the 12-week eccentric training programme.

1.3.3 Functional Ability

The functional ability of participants was generally poorly evaluated throughout these studies; four studies looked at this area (Mafi et al., 2001; Roos et al., 2004; Herrington et al., 2007; Chester et al., 2007). However, there were some results that showed that eccentric calf-muscle training had a positive effect on the functional ability of participants. Mafi et al., (2001) showed that 82% of participants in their eccentric group had resumed their previous activity level after 12 weeks (P<0.002). Herrington et al., (2007) showed that the main difference between their eccentric training group and the comparison group was a return to function; 6/8 participants in the eccentric group returned to full activity after 12 weeks training whereas none of the comparison group did. In Roos et al., (2004), the eccentric group showed a significant increase of the “Function in Daily Life” and “Sport and Recreational Function” subscales of the FAOS over the 12 weeks.

1.4 Discussion

The earliest study, by Alfredson et al., (1998), described an eccentric calf-muscle training programme subsequently used in other studies in this review. However, this programme appeared to be based on clinical experience as the study failed to explain the reasoning behind each individual component of the programme such as length, intensity and frequency. This, unfortunately, appeared to demonstrate a lack of scientific basis for this very commonly used training programme. However, despite this, the study showed very good results for the eccentric training group who recovered fully after the 12-week programme. The study would certainly support the use of eccentric calf-muscle training, as a conservative form of treatment for chronic Achilles tendinopathy, instead of treating participants surgically. In other respects, it was the only study that failed to mention ethics and the apparent lack of ethical approval would be a serious flaw to consider when analysing the results.

Mafi et al., (2001) gave a good description of their treatment programme, which meant that it could be easily reproduced in a clinical setting. This study used the same eccentric calf-muscle training programme as described by Alfredson et al., (1998) and it was chosen on the basis of the “very good results” yielded in the previous study. However, Mafi et al., (2001) failed to examine, or even question, what made this specific training programme successful and it did not explain the reasoning, if any, behind each of its components.

The eccentric group in this study showed significantly better results than the concentric group for all the outcome measures used and these results further support Alfredson’s work on the beneficial effects of eccentric calf muscle training for Achilles tendinopathy (Alfredson et al., 1998). However, it is questionable whether these results would still be observed if the length, frequency or intensity of the programme was altered.

The study by Silbernagel et al., (2001) failed to describe the participants underlying diagnosis sufficiently. All participants were said to have proximal Achillodynia but from this diagnosis, it cannot be established whether this was due to tendinopathy or partial rupture. Thus caution must be applied when comparing the results of this study with other studies that looked specifically at Achilles tendinopathy.

It must also be noted that the eccentric calf-muscle training group received information regarding the aetiology of Achilles disorders as well as weekly supervision of the programme and a pain monitoring model; these co-interventions could contaminate the effect of the basic eccentric calf-muscle training programme and the results must be examined with this in mind. Silbernagel et al., (2001) was one of two studies that did not use Alfredson’s training programme. The study used an eccentric/concentric training programme but, as with some of the other studies, it failed to explain the reasoning behind the length, frequency and intensity of these exercises.

A different approach was taken by Fahlstrom et al., (2003); this study not only looked at an eccentric calf-muscle training programme but tested this on participants with mid-portion and insertional Achilles tendon pain. This approach highlighted an unexplained difference in response to treatment between these two conditions that was not seen in any of the other studies whereby 89% of the mid-portion tendons had good results and only 32% of the insertional tendons had good results.

This study used the basic eccentric training programme as described by Alfredson et al., (1998). Once again, the components of this programme were not discussed, nor was the use of this specific programme justified other than to say that it “previously has been shown to give good results”. Overall, in the case of mid-portion Achilles pain, this study further supported the use of this eccentric calf-muscle training programme for the treatment of Achilles tendinopathy.

The pilot study by Herrington et al., (2007) involved an experiment group that received treatment of deep frictional massage, ultrasound and stretches along with a 12-week eccentric calf-muscle training programme. Similar to the study by Silbernagel et al., (2001), it should be considered that these co-interventions could have contaminated the effect of the basic eccentric calf-muscle training programme when analysing the results of this study. One drawback of this study is the lack of an “exercise only” group and thus, no conclusions could be laid down regarding the effects of eccentric training as a single modality.

Once again, this study used the eccentric programme as described by Alfredson et al., (1998); it also failed to provide reasoning for the individual components. The study took a unique approach by using the VISA-A questionnaire as the main outcome measure; this focused the research more on functional ability compared with other studies which focused mainly on pain as the primary outcome measure (Alfredson et al., 1998; Mafi et al., 2001; Fahlstrom et al; 2003; Chester et al., 2007, Silbernagel et al., 2001).

Roos et al., (2004) was the second of two reviewed studies (Roos et al., 2004; Silbernagel et al., 2001) which examined the long-term benefits of eccentric calf-muscle training for the treatment of Achilles tendinopathy and it showed that this training results in improvements that last at least a year. The study was also one of just two studies (Roos et al., 2004; de Vos et al., 2007) that looked at the participants’ rates of compliance with the programme which is important when assessing and interpreting results. The results showed good compliance with greater than 75% of recommended training completed in the first few weeks although this decreased over time and only 50% compliance was reported at 12 weeks.

The study used the training programme as previously described by Alfredson et al., (1998). It also failed to explain why the various components were used at specific levels. However, this study by Roos et al., (2004) did alter the intensity of the training by opting to use a gradual onset of intensity to help diminish initial muscle soreness. Unlike Chester et al., (2007), this change in components of the programme did not appear to adversely affect the results.

A well-designed study by de Vos et al., (2007) also assessed compliance similar to Roos et al., (2004). However, unlike Roos et al., (2004), this study reported good/excellent compliance of 74% for the eccentric group after 12 weeks. de Vos et al., (2007) took compliance issues to a higher level by calculating the association between outcome and compliance. It showed that better patient compliance for the eccentric programme led to better results; while these differences were not statistically significant, they would indicate that further work on the level of patient compliance should be done.

Chester et al., (2007) was an important pilot study as it used an eccentric calf-muscle training programme similar to that described by Alfredson et al., (1998). However, this study altered two of the basic components. The intensity at which the exercises were performed was based on the subject’s physical ability and their level of pain provocation. The frequency was altered so that the exercises were only performed once a day. The results of this study showed no significant improvement for the participants treated with eccentric calf-muscle training.

This lack of improvement did not occur in any other study of this review. Thus, a question could arise as to whether these results were due to the decreased intensity and reduced frequency of the exercises performed. This study might indicate that poorer results are found with a change in the programme’s components. However, the study did not include a comparison group and, therefore, the proposition that a change in components affected the results of the programme is hypothetical.

1.5 Conclusion

This review yielded no definitive answers regarding the effect of eccentric calf-muscle training on pain and functional ability for patients with chronic Achilles tendinopathy. The eight studies used a couple of eccentric training programmes, various outcome measures, different comparison groups and several co-interventions. Thus, as the variation is so wide, the results could only be considered individually and could not be directly compared. Overall, the findings of this review would suggest that eccentric calf-muscle training did have a beneficial effect on both pain and functional activity. However, the extent of the benefit could not be definitively established from the available research.

On the basis of this review, more research is required into the effect of eccentric calf-muscle training on the functional ability of participants. From a clinical viewpoint, it is relevant to consider the use of outcome measures that focus directly on the function of the Achilles tendon and patient activity levels by using specific measures such as the VISA-A questionnaire. Although pain is well researched, further, specific research is required to comprehensively determine the effect of eccentric calf-muscle training on pain associated with chronic Achilles tendinopathy.

However, the main area that requires research is the actual content of the eccentric calf-muscle training programme. All the studies revealed major gaps in their reasoning for the components of their training programmes and many questions can be raised in this regard including: Why did the training last for 12 weeks? Would a change in intensity have altered the results? Did the frequency of the training affect the results?

Consequently, in light of these unanswered questions, the aim of the proposed study, outlined in Section 2, is to consider specifically a change in the frequency of eccentric calf-muscle training and to determine if this has an effect on the pain and functional ability associated with chronic Achilles tendinopathy.

Section 2: Research Proposal- “To investigate the effect of frequency as a component of eccentric calf-muscle training in the management of chronic Achilles tendinopathy”

2.1 Introduction

The most prominent issue raised in the literature review (Section 1) is the serious lack of evidence to justify the various components of eccentric calf-muscle training programmes. Most of the studies used an eccentric training programme as described by Alfredson et al., (1998). Many claimed to use this programme as it had previously shown good results. However, such good results do not necessarily mean it is the best form of treatment and research is constantly required to examine if current treatments could be improved.

2.2 Aim

Consequently, this study aims to compare eccentric calf-muscle training completed, at two different frequencies, on patients with chronic Achilles tendinopathy.

2.3 Objectives

• To determine if altering the frequency of an eccentric calf-muscle training programme affects the overall outcome of this treatment.
• To evaluate whether an altered eccentric calf-muscle training programme has any effect on participants’ pain and functional ability.

2.4 Proposed Design

2.4.1 Type of Study
The study will be a randomised, controlled study with a prospective design.

2.4.2 Ethics
Ethical approval for the study will be sought from the Faculty of Health Science Research Ethics Committee, Trinity College, Dublin.

2.4.3 Participants

The study will aim to involve 50 participants; a multi-centre design will be used in order to increase the available number of patients. Participants will be recruited from patients who present to physiotherapy outpatients departments of St. James Hospital, Dublin and the Adelaide and Meath Hospital incorporating the National Children’s Hospital, Dublin. General Practitioners in the catchment area of these hospitals will also be asked to refer to any suitable patients for the study. The research will be carried out over a 6-month period depending on the number of participants’ available, beginning in Spring, 2008.

2.4.4 Diagnosis

Researcher #1 will clinically examine all patients to confirm a diagnosis of mid-portion Achilles tendinopathy. Diagnosis will include the presence of palpable, painful swelling 2–6cm above the tendon insertion on the calcaneus and a negative Thompson’s test (Magee, 1997). Ultrasound scanning or MRI will not be used to confirm diagnosis as both of these methods have been shown to result in both false negative and positive findings on initial examination (Khan et al., 2003).

2.4.5 Inclusion and Exclusion Criteria

The following inclusion and exclusion criteria will be applied to all patients, to ensure that they are suitable and can safely participate in this study.

Inclusion Criteria –
1. Diagnosis of mid-portion Achilles tendinopathy;
2. Achilles tendon pain for 3 months;
3. Aged between 18 and 70 years.

Exclusion Criteria –
1. Patients receiving other forms of treatment for their Achilles tendinopathy;
2. Patients with bilateral Achilles tendon pain;
3. Patients with a systematic illness, diabetes, history of Rheumatoid Arthritis or other illness that could interfere with the study;
4. Patients who have had previous surgery, fracture or serious injury to the affected foot, ankle, knee or hip.

2.4.6 Consent and Randomisation

After patients are deemed appropriate for the programme by researcher #1, the study will be fully explained to them and their participation sought. If patients consent to treatment, they will be sequentially randomised by researcher #2 into an experiment or comparison group, by picking an envelope from a box.

2.4.7 Outcome Measures

Two outcome measures will be used during the study. The pain will be measured at rest and during walking, using the VAS. This is a 100mm horizontal Visual Analogue Scale (Appendix B), which has good reliability and validity (Huskinsson 1974; Melzack and Katz 1999). Patients’ functional ability will be measured using the VISA-A questionnaire (Appendix C), which measures function in daily living and sporting activity. This measure has been established as both reliable and valid (Robinson et al., 2001) and has previously been successfully used to monitor clinical progress of Achilles tendinopathy (Sayana et al., 2007). At baseline, participants will complete both outcome measures. The results will be analysed by researcher #1 who, in order to avoid bias, will at all times remain blinded to participants group allocation.

2.4.8 Eccentric Calf-Muscle Training Programme

All participants will be fully instructed by researcher #2 on how to perform the exercise programme and they will be instructed on the progression of exercises. Both groups will do an eccentric calf-muscle training programme as described by Alfredson et al., (1998). The experiment group will only do this training programme once daily and the comparison group will adhere to Alfredson’s frequency by completing it twice daily, morning and evening (Alfredson et al., 1998). All participants will do the programme for 7 days a week for 12 weeks.

Participants will begin their exercise in an upright body position with their ankle joint in plantar flexion and the bodyweight through their forefoot (see Appendix A, Image 1). Their calf-muscle will then be loaded by getting the participant to lower their heel beneath their forefoot (Image 2). They will only load their calf-muscle eccentrically and participants should use their non-injured leg to return to their starting position. This exercise will be completed with the participant’s knee straight (Image 2) to activate the gastrocnemius muscle and, as a separate exercise, with their knee bent (Image 3) to activate the soleus muscle.

The participant’s body weight will initially act as the loading for the exercise; however, as the exercise programme progresses, further weights e.g. a backpack may be used to increase loading (Image 4). A weights machine may also be used if further heavy loading is required (Image 5). The speed of exercises will not matter as eccentric calf-muscle training does not appear to be velocity specific (Kellis et al., 1995).

All participants will do 3 sets of 15 repetitions of each exercise during every training session. Participants will be informed that muscle soreness can be expected in the initial weeks of the programme and that they should continue exercises even if they experience pain but should stop if the pain becomes disabling. During the 12-week training period, participants should not walk/run if they experience pain or more than mild discomfort.

2.4.9 Evaluation

Researcher #2 will evaluate participants after 4 and 8 weeks to ensure that the exercises are being carried out correctly. Researcher #1 will assess the two outcome measures at these stages. The purpose of monitoring the participants at various intervals throughout the treatment period is to enable the study to evaluate which time period will generate the most significant changes.

After the 12-week programme is complete, researcher #1 will clinically examine all participants and assess their outcome measures. The results obtained from this study will be entered into a spreadsheet on Microsoft Excel Version 9.0 and will then be analysed using appropriate descriptive statistics, graphs and tables.

The results obtained from participants in this study will be confidential and used for research purposes only.

2.5 Conclusion

It is hoped that this proposed study, and its results, will help to establish whether varying the frequency of eccentric calf-muscle training affects the outcome of this training programme as a treatment for chronic Achilles tendinopathy. It should help to establish whether an altered frequency specifically affects the outcome measures of pain and functional ability. Furthermore, it will provide valuable information on the overall benefits of eccentric calf-muscle training for the treatment of chronic Achilles tendinopathy.

The VISA-A questionnaire: An index of the severity of Achilles tendinopathy

IN THIS QUESTIONNAIRE, THE TERM PAIN REFERS SPECIFICALLY TO PAIN IN THE ACHILLES TENDON REGION

1. For how many minutes do you have stiffness in the Achilles region on first getting up?
   
   
                                                                                                                                       
2. Once you are warmed up for the day, do you have pain when stretching the Achilles tendon fully over the edge of a step? (keeping the knee straight).
3. After walking on flat ground for 30 minutes, do you have pain within the next 2    hours? (If unable to walk on flat ground for 30 minutes because of pain, score 0 for this question)
4. Do you have pain walking downstairs with a normal gait cycle?
5. Do you have pain during or immediately after doing 10 (single leg) heel raises from a flat surface?
6. How many single-leg hops can you do without pain?
7. Are you currently undertaking sport or other physical activity?
   0- Not at all
   4- Modified training +/- modified competition
   7- Full training +/- competition but not at the same level as when symptoms began
   10- Competing at the same or higher level as when systems began
8. Please complete EITHER A, B or C in this question.

• If you have no pain while undertaking Achilles tendon loading sports please complete Q8a only.
• If you have pain while undertaking Achilles tendon loading sports but it does not stop you from completing the activity, please complete Q8b only.
• If you have pain that stops you from completing Achilles tendon loading sports, please complete Q8c only.

(a). If you have no pain while undertaking Achilles tendon loading sports, for how long can you train/practise?

NIL        1-10mins     11-20mins     21-30mins  >  30mins

—          —           —             —              —

OR

(b). If you have some pain while undertaking Achilles tendon loading sport, but it does not stop you from completing your training /practise for how long can you train/ practise?

NIL        1-10mins     11-20mins     21-30mins  >  30mins

—          —           —             —              —

OR

(c). If you have pain that stops you from completing your training/ practise in Achilles tendon loading sport, for how long can you train/ practise?

NIL        1-10mins     11-20mins     21-30mins  >  30mins                                                           —          —           —             —              —                          —