Sports and Exercise-Related Tendinopathies
Sports and Exercise-Related Tendinopathies
Tendinopathies are common and often cause long-lasting symptoms of pain and dysfunction which negatively impact on working and/or sporting capacity. Thus, preventive strategies for tendinopathy seem warranted. However, little research on the prevention of tendinopathy has been published. In 1992, van Mechelen et al introduced the sports injury prevention research model. This model will be used as a framework for describing what is known already, and what should be targeted in future research projects.
Several studies have been published on the frequency of sport-related and exercise-related tendinopathies. However, comparison and interpretation of results is difficult due to a lack of consistent case definitions and inappropriate time-loss-based injury registration methods. Most studies are performed in selected populations such as elite athletes, or in participants of one specific sport. The definition of tendon problems is often unclear since tendon pain, US tendon abnormalities and sport-specific diagnoses such as jumper's knee or tennis elbow are used interchangeably. Many people continue their work or sporting activities despite their chronic overuse injury and/or tendon pain. This means that in many epidemiological studies, despite their prevalence tendinopathies are not included in the incidence rate as new injuries that cause time loss from work or sports.
Bahr recommended the quantification of overuse injuries in a standardised way using prevalence (not incidence) in prospective studies with continuous or serial measurements of symptoms. Valid and sensitive scoring instruments that measure pain and functional level should be used, and severity should be determined in relation to this rather than from time lost from sport/work (as many athletes continue to compete despite pain). The VISA-A and VISA-P are examples of valid, sensitive and cross-culturally adapted questionnaires which measure pain, function and sports participation in athletes with Achilles or patellar tendon problems (discussed above). Recently, the aforementioned recommendations led to the development of a new method, including a questionnaire, for the registration of overuse problems.
Since overuse injuries, including tendinopathies, have a multifactorial aetiology, establishing the mechanism of injury is not an easy task. Both intrinsic and extrinsic factors have been described in the literature, but there is little robust and often even conflicting evidence for these. A link between the genetic profile and tendinopathy has been reported and some people may be more susceptible to tendinopathy than others. Genetic screening to identify people at risk of developing tendinopathy might play an important role in future prevention strategy. However, among all potential risk factors, the load to the tendon is considered the most important factor in the aetiology of sport-related and exercise-related tendon pathology and pain. Moreover, load is a factor that can be modified by prevention strategies.
A promising development is UTC. Preliminary data show that this non-invasive, operator-independent imaging technique can visualise load-dependent changes in a very early stage, at least for the large lower extremity tendons.
Another potential option is to monitor the volume of loading to which a tendon is exposed (eg, number of jumps, hours of training, distance run, etc); however, there is an inherent inaccuracy in any such measurement utilised to date. Visnes and Bahr showed a significant difference between healthy and volleyball players with jumpers knee in hours dedicated to volleyball, jump training and number of sets played. In a sample population of Australian football players, no correlation was observed between the distance covered during the game and the magnitude of change in tendon structure. (ISTS 2012 abstract, in press) The major limitation of global positioning system data is that it quantifies distance and speed travelled, where the impact of load on tendon structure may be more complex (ie, jumps performed in each session, changes in surfaces, etc).
Clarification of the complex relationship between load (including an individual's own unique biomechanics) and tendon changes together with other prospective studies investigating the various (modifiable) risk factors and their influence on the tendon would certainly aid in establishing more appropriate and effective preventive measures. Currently, in most situations, the clinician is not in a position to provide guidance in terms of how much load an individual patient can safely engage in to prevent the development of tendinopathy. However, cautioning against sudden changes to tendon loading may be prudent.
Developing and introducing training programmes that teach coaches and athletes how to load tendons in the most appropriate way, and how to change their strength, flexibility and proprioception in the most efficient way could be important preventive measures to reduce the risk of developing tendinopathy.
So far, most studies of injury prevention in sporting populations have focused on reducing the incidence of acute injuries such as ACL rupture or ankle sprain. To our knowledge, only a few studies have targeted the prevention of tendinopathy. A prospective study in elite female soccer players demonstrated that soccer-specific balance training can reduce the incidence of patellar and Achilles tendinopathy. A dose–effect relationship between the duration of balance training and injury incidence was found. Fredberg et al reported on a randomised controlled trial (RCT) in which elite soccer players were followed over 12 months with use of ultrasonography and injury registration. Half the teams were randomised to an intervention group with prophylactic eccentric training and stretching of the Achilles and patellar tendons during the season. This study demonstrated that the prophylactic training reduced the risk of developing US abnormalities in the patellar tendons, but had no positive effects on the risk of injury. On the contrary, in asymptomatic players with ultrasonographically abnormal patellar tendons, prophylactic eccentric training and stretching increased the injury risk.
Only programmes that can and will be adopted by athletes, coaches and sporting associations will be successful in preventing injuries. Hence, implementation strategies and effects of research are necessary to evaluate if preventive methods really are being adopted by the athletes. Finally, the costs and effectiveness of the introduced preventive measures should be evaluated by repeating step 1, or preferably by conducting an RCT.
Prevention
Tendinopathies are common and often cause long-lasting symptoms of pain and dysfunction which negatively impact on working and/or sporting capacity. Thus, preventive strategies for tendinopathy seem warranted. However, little research on the prevention of tendinopathy has been published. In 1992, van Mechelen et al introduced the sports injury prevention research model. This model will be used as a framework for describing what is known already, and what should be targeted in future research projects.
Step 1: Magnitude of the Problem
Several studies have been published on the frequency of sport-related and exercise-related tendinopathies. However, comparison and interpretation of results is difficult due to a lack of consistent case definitions and inappropriate time-loss-based injury registration methods. Most studies are performed in selected populations such as elite athletes, or in participants of one specific sport. The definition of tendon problems is often unclear since tendon pain, US tendon abnormalities and sport-specific diagnoses such as jumper's knee or tennis elbow are used interchangeably. Many people continue their work or sporting activities despite their chronic overuse injury and/or tendon pain. This means that in many epidemiological studies, despite their prevalence tendinopathies are not included in the incidence rate as new injuries that cause time loss from work or sports.
Bahr recommended the quantification of overuse injuries in a standardised way using prevalence (not incidence) in prospective studies with continuous or serial measurements of symptoms. Valid and sensitive scoring instruments that measure pain and functional level should be used, and severity should be determined in relation to this rather than from time lost from sport/work (as many athletes continue to compete despite pain). The VISA-A and VISA-P are examples of valid, sensitive and cross-culturally adapted questionnaires which measure pain, function and sports participation in athletes with Achilles or patellar tendon problems (discussed above). Recently, the aforementioned recommendations led to the development of a new method, including a questionnaire, for the registration of overuse problems.
Step 2: Establishing Aetiology and Mechanisms of Injury
Since overuse injuries, including tendinopathies, have a multifactorial aetiology, establishing the mechanism of injury is not an easy task. Both intrinsic and extrinsic factors have been described in the literature, but there is little robust and often even conflicting evidence for these. A link between the genetic profile and tendinopathy has been reported and some people may be more susceptible to tendinopathy than others. Genetic screening to identify people at risk of developing tendinopathy might play an important role in future prevention strategy. However, among all potential risk factors, the load to the tendon is considered the most important factor in the aetiology of sport-related and exercise-related tendon pathology and pain. Moreover, load is a factor that can be modified by prevention strategies.
A promising development is UTC. Preliminary data show that this non-invasive, operator-independent imaging technique can visualise load-dependent changes in a very early stage, at least for the large lower extremity tendons.
Another potential option is to monitor the volume of loading to which a tendon is exposed (eg, number of jumps, hours of training, distance run, etc); however, there is an inherent inaccuracy in any such measurement utilised to date. Visnes and Bahr showed a significant difference between healthy and volleyball players with jumpers knee in hours dedicated to volleyball, jump training and number of sets played. In a sample population of Australian football players, no correlation was observed between the distance covered during the game and the magnitude of change in tendon structure. (ISTS 2012 abstract, in press) The major limitation of global positioning system data is that it quantifies distance and speed travelled, where the impact of load on tendon structure may be more complex (ie, jumps performed in each session, changes in surfaces, etc).
Clarification of the complex relationship between load (including an individual's own unique biomechanics) and tendon changes together with other prospective studies investigating the various (modifiable) risk factors and their influence on the tendon would certainly aid in establishing more appropriate and effective preventive measures. Currently, in most situations, the clinician is not in a position to provide guidance in terms of how much load an individual patient can safely engage in to prevent the development of tendinopathy. However, cautioning against sudden changes to tendon loading may be prudent.
Steps 3 and 4: Developing, Introducing and Evaluating a Training Programme
Developing and introducing training programmes that teach coaches and athletes how to load tendons in the most appropriate way, and how to change their strength, flexibility and proprioception in the most efficient way could be important preventive measures to reduce the risk of developing tendinopathy.
So far, most studies of injury prevention in sporting populations have focused on reducing the incidence of acute injuries such as ACL rupture or ankle sprain. To our knowledge, only a few studies have targeted the prevention of tendinopathy. A prospective study in elite female soccer players demonstrated that soccer-specific balance training can reduce the incidence of patellar and Achilles tendinopathy. A dose–effect relationship between the duration of balance training and injury incidence was found. Fredberg et al reported on a randomised controlled trial (RCT) in which elite soccer players were followed over 12 months with use of ultrasonography and injury registration. Half the teams were randomised to an intervention group with prophylactic eccentric training and stretching of the Achilles and patellar tendons during the season. This study demonstrated that the prophylactic training reduced the risk of developing US abnormalities in the patellar tendons, but had no positive effects on the risk of injury. On the contrary, in asymptomatic players with ultrasonographically abnormal patellar tendons, prophylactic eccentric training and stretching increased the injury risk.
Only programmes that can and will be adopted by athletes, coaches and sporting associations will be successful in preventing injuries. Hence, implementation strategies and effects of research are necessary to evaluate if preventive methods really are being adopted by the athletes. Finally, the costs and effectiveness of the introduced preventive measures should be evaluated by repeating step 1, or preferably by conducting an RCT.