Seth O’Neill

75 Plantarflexor Muscle Power Deficits In Runners With Achilles Tendinopathy

Introduction Muscle power of the Plantarflexors has been shown to be a prospective risk factor for Achilles Tendinopathy (AT).1 Several studies have shown associations between Achilles tendinopathy and Plantarflexor power, but little thought has been given to how the individual muscles of the Triceps Surae are affected. Aim – Compare the Triceps Surae power of runners with and without AT. Method 41 runners with AT and 27 runners without a history of AT (control group) have participated in this study. Plantarflexor muscle power was measured during concentric and eccentric muscle contractions at 90º/sec using an Isokinetic dynamometer. Testing utilised a knee extended position (both Gastrocnemius and Soleus) and an 80º knee flexed position (significantly inhibiting Gastrocnemius).2,3 Results Independent t tests revealed statistically significant differences between healthy controls and participants with AT for both test speeds and positions (p = 0.004 for concentric 90º/sec in knee flexion, p ≤ 0.001 for all other test speeds and positions). Discussion This study shows that participants with AT have weaker Plantarflexors than healthy runners. It also shows that the deficits in power appear similar whether testing was performed with knee extension or flexion, since Gastrocnemius does not contribute significantly to force generation in knee flexion it seems feasible that the Soleus is responsible for the majority of observed deficits in both positions. Pain was not reproduced during testing for any individual and therefore did not limit performance. It is possible these neuromuscular deficits are due to central motor inhibition or potentially pre-existing weakness. Resolution of these muscle deficits may be essential to return to normal function, it is unclear whether normal rehabilitation successfully resolves these deficits. Abstract 75 Figure 1 The peak Plantarflexor power for participants with AT and the control group in knee extension (both Gastrocnemius and Soleus active) Abstract 75 Figure 2 he peak Plantarflexor power for participants with AT and the control group in knee flexion (Gastrocnemius significantly inhibited) Conclusion Weakness of Soleus maybe responsible for the majority of the deficits observed in participants with AT. Further work needs to determine how current clinical interventions alter these deficits. References Lauber, et al . Physiological reports. 2014;2, doi:10.14814/phy2.12044 Mahieu, et al. Am J Sports Med. 2006;34:226–235 Reid, et al. Physical Therapy in Sport. 2012;13:150–155

76 Eccentric Exercises For Achilles Tendinopathy Do Not Fully Resolve Plantarflexor Muscle Power Deficits

Introduction Our previous work has shown a clear clinical and statistical significant difference in Plantarflexor power between healthy controls and participants with Achilles tendinopathy (AT), p ≤ 0.004 for all test positions and speeds. This data showed that the Soleus is responsible for the majority of the observed power deficits. Aim - Determine how an eccentric regime alters Plantarflexor muscle power. Method 24 runners with AT completed an eccentric training regime for 12 weeks.1 Muscle power was measured at baseline and 12 weeks follow up using an Isokinetic dynamometer. Testing utilised a knee extended and knee flexed position and concentric and eccentric speeds of 90º/sec. The control group comprised 27 healthy runners without AT tested on a single occasion. Abstract 76 Figure 1 The peak Plantarflexor power for participants with AT and the control group in knee extension (both Gastrocnemius and Soleus active) at baseline and post 12 weeks eccentric regime Abstract 76 Figure 2 The peak Plantarflexor power for participants with AT and the control group in knee flexion (significantly inhibiting Gastrocnemius) at baseline and post 12 weeks eccentric regime Results Paired t tests show significant changes from baseline to post intervention for both test speeds and positions (p = 0.008 – p < 0.001). After the intervention there were still significant differences between healthy controls and the AT group for both test speeds in knee extension (p = 0.048 – p < 0.001) but only eccentric power differed in the flexed knee position (p = 0.26 for concentric and 0.026 for eccentric). Discussion This is the first study to compare Plantarflexor power pre and post intervention between participants with AT and healthy controls. The eccentric regime significantly improved Plantarflexor power for the tested parameters, however the regime did not fully resolve the deficits in muscle function. The concentric deficits vary markedly between test positions, since they are greatest in knee extension we may assume Gastrocnemius is responsible and not fully rehabilitated.2 The eccentric deficits are similar in both knee extension and flexion and it may be that Soleus was not fully rehabilitated with the intervention. These residual deficits in muscle power may explain why previous injury is a risk factor for further tendinopathy. Conclusion A 12 week eccentric protocol does not completely resolve muscle deficits associated with AT. References Alfredson, et al. AJSM. 1998;26:360–366 Lauber, et al . Physiological reports. 2014;2, doi1 0.14814/phy2.12044

4 The Effect Of Eccentric Exercises On Plantar-flexor Power In Healthy Individuals

Introduction Plantar-flexor power below 50 Nm has been shown to be predictive of Achilles tendinopathy in army recruits [Mahieu, 2006]. It appears that muscle weakness may expose the tendon to greater load. As such, eccentric regimes have been proposed as an effective prophylactic intervention [Fredberg, 2008]. However, little is known about how a typical eccentric regime alters muscle power. Aim – Investigate the effect of eccentric exercise on plantar-flexor power in healthy individuals. Methods A test re-test study was performed with 32 healthy volunteers. Participants were assessed using a Cybex® NORM Isokinetic Dynamometer. They then completed a 12-week eccentric calf exercise programme on one leg and were re-tested [Alfredson, 1998]. The test protocol used speeds of 90°/s concentrically and 90°/s eccentrically, performed with the knee extended. Results were analysed using a paired t test (p < 0.05). Results Significant improvements in plantar-flexor power were seen in the trained leg compared to the untrained leg following the intervention (p = 0.007). The cohort was separated into two groups depending on initial plantar-flexor power measured during the concentric 90°/s phase (Weak: <50 Nm. Strong: >50 Nm). Weak participants improved on average by 58% (p < 0.005) compared to strong participants who improved on average by 16% (p < 0.12, non-significant in eccentric peak torque). Abstract 4 Figure 1 Mean plantar-flexion average power before and after eccentric exercise (±SEM) Discussion The results show a significant improvement in power after the intervention, with much larger gains in weaker individuals than stronger individuals. Furthermore, strong individuals did not show a significant improvement in the eccentric phase. The finding amongst stronger individuals may result from a failure to apply sufficient additional weight necessary to stimulate neuromuscular adaptation. This could explain why previous research using eccentric loading failed to change the risk of developing Achilles tendinopathy [Fredberg, 2008]. Abstract 4 Figure 2 Mean plantar-flexion peak torque before and after eccentric training (± SEM) Conclusions Eccentric loading adapts plantar-flexor muscle power, which may provide protection against Achilles tendinopathy.Improvements in plantar-flexor power associated with eccentric training depend on initial power measurements. Individuals able to generate more than 50Nm concentric force, may require additional loading to stimulate neuromuscular adaptations. References Mahieu et al. AJSM. 2006;34:226–235 Fredberg et al. AJSM. 2008;36:451–460 Alfredson et al. AJSM. 1998;26:360–366

49 Effect Of Eccentric Training On Isokinetic Endurance Of Calf With Reliability Testing

Introduction Achilles tendinopathy is a common problem among athletes (Jarvinen, Kannus et al. 2005). Various risk factors exist and poor endurance is likely to be one of these (Silbernagel, Gustavsson et al. 2006, Malliaras, Barton et al. 2013). Eccentric training is an effective treatment for Achilles tendinopathy(Alfredson, Pietila et al. 1998). This study was designed to investigate the potential effect of eccentric training on endurance of the triceps surae muscles to indicate whether endurance could be improved in healthy individuals and to establish whether eccentrics may have a potential role within primary prevention of Achilles tendinopathy. The reliability of endurance measured using isokinetic dynamometry was assessed. Methods 37 volunteers (29 males, 8 females) took part in the reliability study and 32 volunteers (24 males, 8 females) in the effect of eccentrics on endurance study. Subjects were tested using the Cybex Humac Norm© isokinetic dynamometer under controlled conditions, on two occasions (2–7 days apart). The endurance test on both legs was 20 repetitions long, at a velocity of 90°S-1, in both eccentric and concentric movements in bent knee (90°) and straight leg positions. 32 subjects were re-tested after 12 weeks of eccentric training on one leg (with the other leg used as a control). Results Results showed that Total Work Done was a reliable measure of endurance (ICC range 0.75–0.91) but that Fatigue Index and Endurance Ratio were not (ICC range -0.44–0.67). Significant improvements in bent knee (see figure 1) and straight leg positions in concentric; trained and non-trained legs and in eccentric; trained leg only were observed in the low baseline endurance group. Only concentric; trained leg in the bent knee position significantly improved in the high baseline endurance group suggesting that eccentric training has the capacity to improve endurance in those with underlying deficits. Abstract 49 Figure 1 Bent knee There is a statistically significant improvement in all results in Total Work Done over the 12 week period in participants with a low baseline endurance level. The whiskers represent the ranges of all values, the box represents the quartiles above and below the median, the line within the box indicates the median Total Work Done, ‘pre’ represents results before eccentric training and ‘post’ represents results after Discussion This study has identified a reliable isokinetic measure for endurance of the calf muscles and a method for improving calf muscle endurance. Investigation of the potential application of eccentric training as prevention of Achilles tendinopathy requires further research. References Alfredson, H. et al. Am J Sport Med. 1998;26(3):360–366 Jarvinen, TA. et al. Foot Ankle Clin. 2005;10(2):255–266 Malliaras, P. et al. Sports Medicine (Auckland, N. Z.), 43(4):267–286 Silbernagel, KG. et al . Knee surgery, sports traumatology, arthroscopy: official journal of the ESSKA, 14(11):1207–1217

Inspanningsafhankelijke pijn in de kuit bij een 23-jarige man als gevolg van dynamische functionele inklemming van de arteria poplitea.

Deze casus betreft een arteriele inklemming bij een 23-jarige man die naar een fysiotherapeut werd verwezen met inspanningsafhankelijke pijn in de kuit. Het verslag benadrukt het belang van een grondige klinische redenering, met inbegrip van kennis van de hemodynamica. Het geeft een duidelijk beeld van het eenvoudige en effectieve niet-invasieve onderzoek dat de fysiotherapeut uitvoerde. Dit onderzoek gaf aanleiding tot nader vasculair testen, dat resulteerde in vroegtijdige diagnose en adequate operatieve interventie. Het belang van vroegtijdige opsporing van dit soort arteriele disfunctie kan niet voldoende worden benadrukt, vooral wanneer er een vermoeden van onderliggende intimapathologie is, daar de consequenties van een verlate diagnose of inadequate interventie ernstig zijn.