Muscle Activity of the Triceps Surae With Novel Propulsion Heel-Lift Orthotics in Recreational Runners

Distal overactivation of gastrocnemius medialis in persistent plantarflexion weakness following Achilles tendon repair

Structural alterations of the triceps surae and Achilles tendon (AT) can promote plantarflexion weakness one-year following an AT repair, influencing the activation strategies of the Gastrocnemius Medialis (GM) muscle. However, this is yet to be demonstrated. We aimed to determine whether patients with plantar flexion weakness one-year after AT repair show altered GM spatial activation. In this cross-sectional and case-control study, ten middle-aged men (age 34 ± 7 years old, and 12.9 ± 1.1 months post-surgery) with a high AT total rupture score who attended conventional physiotherapy for six months after surgery, and ten healthy control men (age 28 ± 9 years old), performed maximal and submaximal (40, 60 and 90%) voluntary isometric plantarflexion contractions on a dynamometer. The peak plantar flexor torque was determined by isokinetic dynamometry and the GM neuromuscular activation was measured with a linear surface-electromyography (EMG) array. Overall EMG activation (averaged channels) increased when the muscle contraction levels increased for both groups. EMG spatial analysis in AT repaired group showed an increased activation located distally at 85-99%, 75-97%, and 79-97% of the electrode array length for 40%, 60%, and 90% of the maximal voluntary isometric contractions, respectively. In conclusion, patients with persistent plantar flexion weakness after AT rupture showed higher distal overactivation in GM.

Innovative Medial Cushioning Orthoses Affect Peroneus Longus Electromyographic Activity during Running

Background: Over-supination processes of the foot and ankle involving peroneus longus (PL) damage during running sports have been treated conservatively with passive control tools, such as tapes, braces, or external ankle supports, but the effect of orthoses with typical lateral wedging orthoses (TLWO) on the muscular activity of PL during running remains unclear. Here we investigate the effects of innovative medial cushioning orthoses (IMCO) on PL activity during the full running gait cycle. In addition, we wished to ascertain the effects of innovative medial cushioning orthoses (IMCO) on PL activity during running. Methods: Thirty-one healthy recreational runners (mean age 34.5 ± 3.33) with neutral foot posture index scores, were selected to participate in the present study. They ran on a treadmill at 9 km/h wearing seven different orthoses (NRS, IMCO 3 mm, IMCO 6 mm, IMCO 9 mm, TLWO 3 mm, TLWO 6 mm and TLWO 9 mm), randomly performed on the same day while electromyographic activity of the PL muscle was recorded. Statistical intraclass correlation coefficient (ICC) to test reliability was carried out and the Wilcoxon test with Bonferroni’s correction was developed to analyze the differences between the conditions. Results: the reliability of all assessments showed data higher than 0.81, that is, “almost perfect reliability”; all EMG PL values wearing either TLWO or IMCO showed a statistically significant reduction versus NRS during the fully analyzed running gait cycle; the highest difference was set on NRS 23.08 ± 6.67 to TLWO 9 mm 17.77 ± 4.794 (p < 0.001). Conclusions: Muscular EMG activity of the PL during the full running gait cycle decreases when wearing either TLWO or IMCO relative to NRS; therefore, these orthoses could be prescribed to treat the strain and overload pathologies of PL. In addition, IMCO—as it less thick, compared with TLWO—can be used when aiming to achieve better running economy.

Assessment of a New Lateral Cushioned Casting Orthosis: Effects on Peroneus Longus Muscle Electromyographic Activity During Running

Background:

Classical medial wedge (CMW) orthoses have been prescribed to treat overpronation foot pathologies in runners. The effects of a novel supination orthosis (NSO) on the surface electromyography (EMG) activity of the peroneus longus (PL) muscle during a complete cycle of running have yet to be tested.

Purpose/Hypothesis:

The purpose of this study was to compare the EMG activity of the PL in participants wearing CMW orthoses and NSOs versus neutral running shoes (NRS) during a full cycle of running gait. It was hypothesized that the PL muscle activity would be lower for the NSO compared with CMW or NRS.

Study Design:

Controlled laboratory study.

Methods:

Included were 31 healthy recreational runners of both sexes (14 male and 17 female; mean age, 38.58 ± 4.02 years) with a neutral Foot Posture Index and standard rearfoot-strike pattern. Participants ran on a treadmill at 9 km/h while wearing NSO (3-, 6-, and 9-mm thicknesses), CMW (3-, 6-, and 9-mm thicknesses), and NRS, for a total of 7 different conditions randomly selected, while the EMG signal activity of the PL was recorded for 30 seconds. Each trial was recorded 3 times, and the intraclass correlation coefficient (ICC) to test reliability of the measurements was calculated. The Wilcoxon pair to pair nonparametric test with Bonferroni correction was performed to analyze differences among the conditions.

Results:

The reliability of all assessments was almost perfect (ICC, >0.81). For both the CMW and NSO, regardless of thickness, the PL activity was statistically significantly lower compared with the NRS (P < .05 for all). For all CMW thicknesses, the PL activity was lower compared with the respective NSO thicknesses, with the 3-mm thickness having the largest difference (CMW_3mm, 18.63 ± 4.64 vs NSO_3mm, 20.78 ± 4.99 mV; P < .001).

Conclusion:

Both CMW and NSO produced reduced EMG activity of the PL muscle; therefore, they can be prescribed to treat overpronation pathologies without associated PL strain concerns. In addition, the NSO saved the enhancement material placed on the medial-rear side of CMW, making it easier to wear sports shoes.

Clinical Relevance:

Knowing the safety of CMW and NSO will aid in understanding treatments for overpronation pathologies.