Comparison of Interventional Strategies to Improve Recovery after Eccentric Exercise-Induced Muscle Fatigue

The aim of this study was to compare the effects of various recovery techniques on muscle tissue after eccentric exercise-induced muscle fatigue (EIMF). Forty subjects (24.3 ± 2.6 years; 77.45 ± 8.3 kg; 177.0 ± 6.4 cm; 24.66 ± 1.6 kg∙m−2) were randomly assigned to one of the following groups: manual therapy (n =10, MT), mechanical vibration (n = 10, MV), percussion therapy (n = 10, PT) or foam roller (n = 10, FR). The contraction time (Tc) and the radial displacement (Dm) of the gastrocnemius was evaluated through tensiomyography (TMG). The application of the different techniques had positive effects for Tc and Dm in the treated leg compared to the untreated leg (F = 50.01, p < 0.01, η2p = 0.58 and F = 27.58, p < 0.01, η2p = 0.43, respectively) and for the interaction of the factors (Time x Leg x Therapy: F = 5.76, p < 0.01, η2p = 0.32 and F = 5.93, p < 0.01, η2p = 0.33, respectively). The results of the various methods used were similar: Tc (F = 0.17, p = 0.917; η2p = 0.01) and Dm (F = 3.30, p = 0.031, η2p = 0.22). PT interventions show potential for restoring muscle compliance and reducing stiffness, similar to MT and possibly more effective (cost-time relationship) compared to MV or FR.

Immediate Effects of Dry Needling as a Novel Strategy for Hamstring Flexibility: A Single-Blinded Clinical Pilot Study

Context: There are numerous studies on the benefits of dry needling (DN) for pain relief. No studies exist examining the effects of DN on hamstring flexibility. Objective: To determine the immediate effects of DN on hamstring flexibility in healthy subjects with shortened hamstrings. Design: A single-blinded, pretest–posttest clinical pilot study. Setting: A university physiotherapy clinic. Subjects: A total of 15 healthy subjects (female = 11; age = 23.26 [4.3] y) with shortened hamstrings participated in this study. Intervention: Subjects received a single session of DN. Three locations on the hamstring muscle group were needled, each for 1 minute. Main Outcome Measures: The active knee extension test, muscle compliance, passive peak torque, and stretch tolerance were measured at baseline, immediately, and 15 minutes after DN. Results: There were statistically significant improvements in all outcome measures immediately after DN and at the 15-minute follow-up. The effect sizes for all outcome measures were large (Cohen’s d ≥ 0.8). No serious adverse events were observed with DN. Conclusions: This is the first study that demonstrates the beneficial effects of DN on hamstring flexibility, muscle compliance, and stretch tolerance without added stretching. The beneficial effects of DN should encourage clinicians to use DN as a novel strategy for increasing muscle flexibility.

Dry Needling for Hamstring Flexibility: A Single-Blind Randomized Controlled Trial

Context: Hamstring muscle tightness is one of the most common problems in athletic and healthy people. Dry needling (DN) was found to be an effective approach for improving muscle flexibility, but there is no study to compare this approach with static stretching (SS) as a common technique for the increase of muscle length. Objective: To compare the immediate effects of DN and SS on hamstring flexibility in healthy subjects with hamstring tightness. Study Design: A single-blind randomized controlled trial. Setting: A musculoskeletal physiotherapy clinic at Tehran University of Medical Sciences. Subjects: Forty healthy subjects (female: 32, age range: 18–40 y) with hamstring tightness were randomly assigned into 2 groups of DN and SS. Intervention: The DN group received a single session of DN on 3 points of the hamstring muscles, each for 1 minute. The SS group received a single session of SS of the hamstrings, consisting of 3 sets of 30-second SS with a 10-second rest between sets in the active knee extension test (AKET) position. Main Outcome Measures: The AKET, muscle compliance, passive peak torque, and stretch tolerance were measured at the baseline, immediately, and 15 minutes after the interventions. Results: Improvements in all outcomes was better for the DN group than for the SS group. DN increased muscle compliance significantly 15 minutes after the intervention, but it did not improve in the SS group. Conclusion: DN is effective in improving hamstring flexibility compared with SS. One session of DN can be an effective treatment for hamstring tightness and increase hamstring flexibility. The improvements suggest that DN is a novel treatment for hamstring flexibility.

Submental muscle tissue compliance during relaxation, contraction, and after tone-modification interventions

Deviations in muscle tone are presumed to accompany speech motor control deficits in select forms of dysarthria, although there is little confirmation of these associations. For patients experiencing neuromuscular impairments, therapeutic interventions and/or principles have been devised to alleviate tone deviations where they occur and to prevent the development or exacerbation of tone deviations. Potentially therapeutic effects of these interventions on muscle tone in the speech musculature have not been studied empirically. One reason for the paucity of research is that tools for assessing muscle tone in the speech musculature are not generally available. This pilot study explored the feasibility of a commercially available, handheld instrument for measuring submental muscle compliance during relaxed and active conditions in 16 women with normal speech and swallowing. Additionally, the study examined changes in muscle compliance when interventions presumed to impact muscle tone were applied to the submental region. The Myotonometer™ was sensitive to changes in tissue compliance related to active contraction of the submental musculature. Applying ice or vibration to the submental region resulted in no systematic changes in submental tissue compliance in the relaxed or contracted state. Additional research is needed to validate the use of this instrument to reliably assess muscle tone and other contributors to tissue compliance. If successful, studies should examine the sensitivity of the Myotonometer™ to assess intervention-induced tissue compliance changes in patient groups with suspected muscle tone impairments. Further study of intervention effects across muscle groups and dosage levels can help inform clinical decisions about the potential usefulness of tone-altering interventions for the orofacial musculature.

Strain softening is not present during axial extensions of rat intact right ventricular trabeculae in the presence or absence of 2,3-butanedione monoxime

Recent studies of passive myocardial mechanics have shown that strain softening behavior is present during both inflation of isolated whole rat hearts and shearing of tissue blocks taken from the left ventricular free wall in pigs. Strain softening is typically manifested by a stiffer forceextension relation in the first deformation cycle relative to subsequent cycles and is distinguished from viscoelasticity by a lack of recovery of stiffness, even after several hours of rest. The causes of this behaviour are unknown. We investigated whether strain softening is observed in uniaxial extensions of intact, viable, rat right ventricular (RV) cardiac trabeculae. Stretch and release cycles of 5%, 10%, and 15% muscle length were applied at a constant velocity at 26°C. Muscles were tested in random order in the presence and absence of 50 mM 2,3-butanedione monoxime (BDM). Whereas strain softening was displayed by nonviable trabeculae, it was not observed in viable preparations undergoing physiologically relevant extensions whether in the presence or absence of BDM. BDM also had no effect on passive compliance. There was a reversible increase of muscle compliance between the first and subsequent cycles, with recovery after 30 s of rest, independent of the presence of BDM. We conclude that strain softening is neither intrinsic to viable rat RV trabeculae nor influenced by BDM and that passive trabeculae compliance is not altered by the addition of BDM.

Factors Affecting Force Loss With Prolonged Stretching

The purpose of this study was to investigate factors underlying the force loss occurring after prolonged, static, passive stretching. Subjects were tested before and 5-10 min following 20 min of static, passive stretching of the quadriceps (N = 12) or a similar period of no stretch (control, N = 6). Measurements included isometric maximal voluntary contraction (MVC) force, surface integrated electromyographic (iEMG) activity of the quadriceps and hamstrings, evoked contractile properties (twitch and tetanic force), and quadriceps inactivation as measured by the interpolated twitch technique (ITT). Following stretching, there was a significant 12% decrement in MVC with no significant changes in the control group. Muscle inactivation as measured by the ITT and iEMG increased by 2.8% and 20.2%, respectively. While twitch forces significantly decreased 11.7%, there was no change in tetanic force post-stretch. Although possible increases in muscle compliance affected twitch force, a lack of tetanic force change would suggest that post-stretch force decrements are more affected by muscle inactivation than changes in muscle elasticity. Key Words: antagonist, electromyography, maximum voluntary contraction, muscle activation, twitch, tetanus