Acute effects of cold pack on mechanical properties of the quadriceps muscle in healthy subjects

Acute effects of muscle mechanical properties after 2000-m rowing in young male rowers

Background

The mechanical properties of muscles, such as changes in muscle tone and stiffness, are related to sports performance and injuries. Rowers are at increased risk of muscle fatigue and injury during high-repetition and heavy-load cyclic muscle actions. In view of this, the aim of the present study was to investigate the acute effect on muscle tone and stiffness, as well as bilateral muscle asymmetry, in high school rowers after a 2000-meter rowing ergometer test.

Methods

Twelve young male rowers (age = 17.1 ± 0.9 years, body weight = 73.5 ± 9.7 kg) were included in the study. The data of muscle tone (frequency) and stiffness of the posterior deltoids (PD), latissimus dorsi (LD), and rectus femoris (RF) (dominant and non-dominant side) before and after a 2000-m rowing ergometer test were collected using a handheld MyotonPRO device.

Results

After the rowing ergometer test, the muscle tone of dominant side PD, LD, and RF were significantly increased (p < 0.05). On the other hand, the muscle stiffness of the non-dominant side LD and RF, as well as the dominant side PD, LD, and RF were significantly increased after the rowing ergometer test (p < 0.05). The muscle tone and stiffness results showed that the dominant side PD, LD, and RF were all significantly higher than the non-dominant side after the rowing ergometer test (p < 0.05), where bilateral PD and RF exhibits moderate asymmetry (5% < symmetry index < 10%).

Conclusions

After a high-intensity and high-load 2000-m rowing ergometer test, PD, LD, and RF showed increases in muscle tone and stiffness, as well as changes in the symmetry of bilateral muscle mechanical properties.

The Acute Effects of Theragun™ Percussive Therapy on Viscoelastic Tissue Dynamics and Hamstring Group Range of Motion

Handheld percussive therapy (PT) massage guns have seen a rapid rise in use and with-it increased attention within injury prevention and sport performance settings. Early studies have proposed beneficial effects upon range of motion (ROM), however the mechanism behind these increases remains unreported. This study aimed to determine the influence of a minimal frequency PT dose upon ROM and myotonometry outcomes. Twenty participants (N = 20; 13 males and 7 females, height 1.78cm ± 9.62; weight 77.35kg ± 8.46) participants were allocated to either a PT group receiving 2 x 60-seconds (plus 30-seconds rest) via a Theragun™ Pro4 to the hamstrings covering a standardised 20 lengths from proximal to distal via the standard ball attachment at 1 bar of pressure or a control group (CON) of 2-minutes 30-seconds passive supine rest. Pre and post intervention outcomes were measured for ROM via passive straight leg raise (PSLR) and tissue dynamics via MyotonPro (Tone, Stiffness, Elasticity, Relaxation Time). Results showed significant within-group increases (p < 0.0001, ηp2 0.656, +11.4%) in ROM following PT and between group difference against CON (P < 0.026). Significant within-group differences in stiffness (p < 0.016, ηp2 0.144, -6%), tone (p < 0.003, ηp2 0.213, +2%) and relaxation time (p < 0.002, ηp2 0.232, +6.3%) were also reported following PT. No significant difference was reported in elasticity (P > 0.05) or any other between group outcomes. PT therapy can provide an acute increase in hamstring group ROM following a resultant decrease in tissue stiffness.

Interdependence of Tissue Temperature, Cavitation, and Displacement Imaging During Focused Ultrasound Nerve Sonication

Focused ultrasound (FUS) peripheral neuromodulation has been linked to nerve displacement caused by the acoustic radiation force; however, the roles of cavitation and temperature accumulation on nerve modulation are less clear, as are the relationships between these three mechanisms of action. Temperature directly changes tissue stiffness and viscosity. Viscoelastic properties have been shown to affect cavitation thresholds in both theoretical and ex vivo models, but the direct effect of temperature on cavitation has not been investigated in vivo. Here, cavitation and tissue displacement were simultaneously mapped in response to baseline tissue temperatures of either 30 °C or 38 °C during sciatic nerve sonication in mice. In each mouse, the sciatic nerve was repeatedly sonicated at 1.1-MHz, 4-MPa peak-negative pressure, 5-ms pulse duration, and either 15- or 30-Hz pulse repetition frequency (PRF) for 10 s at each tissue temperature. Cavitation increased by 1.8-4.5 dB at a tissue temperature of 38 °C compared to 30 °C, as measured both by passive cavitation images and cavitation doses. Tissue displacement also increased by 1.3- [Formula: see text] at baseline temperatures of 38 °C compared to 30 °C. Histological findings indicated small increases in red blood cell extravasation in the 38 °C baseline temperature condition compared to 30 °C at both PRFs. A strong positive correlation was found between the inertial cavitation dose and displacement imaging noise, indicating the potential ability of displacement imaging to simultaneously detect inertial cavitation in vivo. Overall, tissue temperature was found to modulate both in vivo cavitation and tissue displacement, and thus, both tissue temperature and cavitation can be monitored during FUS to ensure both safety and efficiency.

Objective Assessment of Regional Stiffness in Vastus Lateralis with Different Measurement Methods: A Reliability Study

The objective of this study was to evaluate the reliability of four methods of assessing vastus lateralis (VL) stiffness, and to describe the influence of structural characteristics on them. The stiffness of the dominant lower-limb’s VL was evaluated in 53 healthy participants (28.4 ± 9.1 years) with shear wave elastography (SWE), strain elastography (SE), myotonometry and tensiomyography (TMG). The SWE, SE and myotonometry were performed at 50%, and TMG was assessed at 30%, of the length from the upper pole of the patella to the greater trochanter. The thickness of the VL, adipose tissue and superficial connective tissue was also measured with ultrasound. Three repeated measurements were acquired to assess reliability, using intraclass correlation coefficients (ICC). Pearson’s correlation coefficients were calculated to determine the relationships between methodologic assessments and between structural characteristics and stiffness assessments of the VL. Myotonometry (ICC = 0.93; 95%-CI = 0.89,0.96) and TMG (ICC = 0.89; 95%-CI = 0.82,0.94) showed excellent inter-day reliability whereas with SWE (ICC = 0.62; 95%-CI = 0.41,0.77) and SE (ICC = 0.71; 95%-CI = 0.57,0.81) reliability was moderate. Significant correlations were found between myotonometry and VL thickness (r = 0.361; p = 0.008), adipose tissue thickness (r = −0.459; p = 0.001) and superficial connective tissue thickness (r = 0.340; p = 0.013). Myotonometry and TMG showed the best reliability values, although myotonometry stiffness values were influenced by the structural variables of the supra-adjacent tissue.

Cold-Water Immersion Has No Effect on Muscle Stiffness After Exercise-Induced Muscle Damage

OBJECTIVE

To analyze the effect of cryotherapy on muscle stiffness after exercise-induced muscle damage.

DESIGN

A leg-to-leg comparison model.

SETTING

University research laboratory.

PARTICIPANTS

Thirty (30) untrained men (21.1 ± 1.6 years, 177.6 ± 6.4 cm, 75.9 ± 10.0 kg, and 15.9 ± 2.9% fat mass) with no history of lower-limb injury and no experience in resistance training.

INTERVENTION

All participants underwent a plyometric exercise program to induce muscle damage; however, randomly, one leg was assigned to a treatment condition and subjected twice to cold-water immersion of the lower limb at 10°C (±1°C) for 10 minutes, while the other leg was assigned to control.

MAIN OUTCOMES MEASURES

Longitudinal stiffness and passive transverse stiffness were evaluated on the soleus and gastrocnemius muscles at 4 moments: pre-exercise, immediately after exercise, 24 hours, and 72 hours after the damage protocol. Furthermore, pressure pain threshold (PPT) and maximal voluntary isometric contraction (MVIC) were also assessed in the same periods.

RESULTS

No significant differences between control and cryotherapy were observed in regard to MVIC (P = 0.529), passive longitudinal stiffness (P = 0.315), and passive transverse stiffness (P = 0.218). Only a significant decrease was observed in PPT on the soleus muscle in the cryotherapy compared with the control leg immediately after exercise (P = 0.040).

CONCLUSIONS

The results show that cryotherapy had no influence on muscle stiffness. However, cryotherapy had a positive effect on PPT immediately after exercise.

Positive relationship between passive muscle stiffness and rapid force production

We aimed to examine the relationship among the muscle shear modulus at rest, maximal joint torque, and rate of torque development (RTD). Twenty-seven participants (28 ± 5 years, 13 women) were recruited in the study. The cross-sectional area (CSA) of the medial gastrocnemius (MG) muscle belly and shear modulus at an ankle joint angle of 0° were calculated using magnetic resonance imaging and ultrasound shear wave elastography, respectively. Subsequently, participants performed maximal isometric plantar flexion at 0° ankle joint angle [maximal voluntary contraction (MVC) test] as fast and hard as possible (RTD test). RTD was calculated from the time-torque curve over time intervals of 0-30, 0-50, 0-100, 0-150, and 0-200 ms from the onset of plantar flexion during the RTD test and was normalized by MVC torque to exclude muscle strength. MG CSA correlated significantly with MVC torque (r = 0.572), whereas MG shear modulus did not. In contrast, MG shear modulus correlated significantly with normalized RTD at all time intervals (r = 0.460-0.496). These results suggest that passive muscle stiffness is not associated with muscle force; however, higher passive muscle stiffness at a given joint angle may contribute to rapid force production.

Therapeutic heat and cold around the elbow on the response of median neurodynamic test 1

OBJECTIVE

To compare the effects of the application of therapeutic heat and cold on the mechanical response of the median nerve neurodynamic testing.

DESIGN

Single-blinded randomized crossover trial.

METHODOLOGY

56 asymptomatic university students (mean age = 21.82 ± 1.64 years) of either gender with a limited elbow extension range of motion during a Median Neurodynamic Test 1 were recruited. Each subject was administered 3 testing conditions on separate days with a 24-hr washout period. The interventions included 1) therapeutic moist heat around the elbow, 2) therapeutic cold around the elbow and 3) no thermal agent as a controlled condition. Outcome measure of elbow extension range of motion at the onset of pain and submaximal pain were recorded before the intervention, immediately after the removal of the thermal agents (20^th min) and at 2 subsequent readings of 30 min and 1 hour after the removal of the thermal agent.

RESULTS

There was a significant effect of using a thermal agent with time on the elbow range of motion at the onset of pain [F(2,165) = 3.622, p = 0.029] and submaximal pain[F(2,165) = 3.841, p = 0.023] at the 20th min. A posthoc comparison indicated that at the 20th min the mean elbow range at the onset of pain and submaximal pain for the therapeutic heat condition (mean = 33.5, S.D = 13.37 and mean = 16.80, S.D = 12.99 respectively) was significantly different than the no thermal agent condition (mean = 40.17, S.D = 12.34 and mean = 23.4, S.D = 13.82 respectively). However, therapeutic cold condition did not significantly differ from both the other conditions.

CONCLUSION

Therapeutic heat causes an immediate increase in elbow extension range of motion during a Median Neurodynamic Test1 and testing post the application of thermal agents can alter the test response.

Reduced Neck Muscle Strength and Altered Muscle Mechanical Properties in Cervical Dystonia Following Botulinum Neurotoxin Injections: A Prospective Study

Objective

To evaluate changes in the strength and mechanical properties of neck muscles and disability in patients with cervical dystonia (CD) during a 12-week period following botulinum neurotoxin (BoNT) injections.

Methods

Eight patients with CD volunteered for this prospective clinical cohort study. Patients had received BoNT injections regularly in neck muscles at three-month intervals for several years. Maximal isometric neck strength was measured by a dynamometer, and the mechanical properties of the splenius capitis were evaluated using two myotonometers. Clinical assessment was performed using the Toronto Western Spasmodic Torticollis Rating Scale (TWSTRS) before and at 2, 4, 8, and 12 weeks after the BoNT injections.

Results

Mean maximal isometric neck strength at two weeks after the BoNT injections decreased by 28% in extension, 25% in rotation of the affected side and 17% in flexion. At four weeks, muscle stiffness of the affected side decreased by 17% and tension decreased by 6%. At eight weeks, the muscle elasticity on the affected side increased by 12%. At two weeks after the BoNT injections, the TWSTRS-severity and TWSTRS-total scores decreased by 4.3 and 6.4, respectively. The strength, muscle mechanical properties and TWSTRS scores returned to baseline values at 12 weeks.

Conclusions

Although maximal neck strength and muscle tone decreased after BoNT injections, the disability improved. The changes observed after BoNT injections were temporary and returned to pre-injection levels within twelve weeks. Despite having a possible negative effect on function and decreasing neck strength, the BoNT injections improved the patients reported disability.

Lower limb ice application alters ground reaction force during gait initiation

BACKGROUND:

Cryotherapy is a widely used technique in physical therapy clinics and sports. However, the effects of cryotherapy on dynamic neuromuscular control are incompletely explained.

OBJECTIVES:

To evaluate the effects of cryotherapy applied to the calf, ankle and sole of the foot in healthy young adults on ground reaction forces during gait initiation.

METHOD:

This study evaluated the gait initiation forces, maximum propulsion, braking forces and impulses of 21 women volunteers through a force platform, which provided maximum and minimum ground reaction force values. To assess the effects of cooling, the task - gait initiation - was performed before ice application, immediately after and 30 minutes after removal of the ice pack. Ice was randomly applied on separate days to the calf, ankle and sole of the foot of the participants.

RESULTS:

It was demonstrated that ice application for 30 minutes to the sole of the foot and calf resulted in significant changes in the vertical force variables, which returned to their pre-application values 30 minutes after the removal of the ice pack. Ice application to the ankle only reduced propulsion impulse.

CONCLUSIONS:

These results suggest that although caution is necessary when performing activities that require good gait control, the application of ice to the ankle, sole of the foot or calf in 30-minute intervals may be safe even preceding such activities.