Cross-education effect of vibration foam rolling on eccentrically damaged muscles.

OBJECTIVES: Previous studies showed that vibration foam rolling (VFR) on damaged muscles improves muscle soreness and range of motion (ROM). VFR intervention can also increase the ROM and pain pressure threshold (PPT) in the non-rolling side, known as a cross-education effect. However, this is not clear for the non-rolling side. Therefore, this study aimed to investigate the cross-education effects of VFR intervention on ROM, muscle soreness, and PPT in eccentrically damaged muscles. METHODS: Participants were sedentary healthy male volunteers (n=14, 21.4±0.7 y) who performed eccentric exercise of the knee extensors with the dominant leg and received 90-s VFR intervention of the quadriceps at the nondamaged side 48 h after the eccentric exercise. The dependent variables were measured before the exercise (baseline), before (preintervention), and after VFR intervention (postintervention) 48 h after the eccentric exercise. The Bonferroni post hoc test was used to determine the differences between baseline, preintervention, and postintervention. RESULTS: Results showed that the VFR intervention on the nondamaged side 48 h after the eccentric exercise improved significantly (p<0.05) the knee flexion ROM, muscle soreness at palpation, and PPT compared to baseline. CONCLUSION: VFR intervention on the nondamaged side can recover ROM and muscle soreness in eccentrically damaged muscles.

Effect of daily 3-s maximum voluntary isometric, concentric, or eccentric contraction on elbow flexor strength.

The present study compared a 3-s isometric maximal voluntary contraction (MVC), concentric MVC and eccentric MVC of the elbow flexors performed daily for 5 days a week for 4 weeks for changes in muscle strength and thickness. Young sedentary individuals were assigned to one of three training groups (n = 13 per group) that performed either 3-s isometric, concentric, or eccentric MVC once a day for 20 days, or to a control group (n = 10) that had measurements without training. The participants in the isometric group performed isometric MVC at 55° (0.96 rad) elbow flexion, and those in the concentric or eccentric group performed concentric MVC or eccentric MVC between 10° (0.17 rad) and 100° (1.75 rad) elbow flexion at 30°/s (0.52 rad/s) on an isokinetic dynamometer. MVC isometric torque at 20° (0.35 rad), 55° (0.96 rad), and 90° (1.57 rad) elbow flexion, MVC concentric and eccentric torque at 30°/s (0.52 rad/s) and 180°/s (3.14 rad/s), and muscle thickness (MT) of biceps brachii and brachialis were measured before and several days after the 20th exercise session. The control group did not show any changes. The eccentric group showed increases (p < 0.01) in isometric (three angle average: 10.2 ± 6.4%), concentric (two velocity average: 12.8 ± 9.6%), and eccentric MVC torque (12.2 ± 7.8%). An increase (p < 0.05) was limited for isometric MVC torque (6.3 ± 6.0%) in the concentric group, and for eccentric MVC torque (7.2 ± 4.4%) in the isometric group. No significant changes in MT were evident for all groups. Performing one 3-s MVC a day increased muscle strength, but eccentric MVC produced more potent effects than isometric or concentric MVC.

Comparison between concentric-only, eccentric-only, and concentric-eccentric resistance training of the elbow flexors for their effects on muscle strength and hypertrophy.

PURPOSE: This study compared concentric-eccentric coupled (CON-ECC), concentric-only (CON), and eccentric-only (ECC) resistance training of the elbow flexors for their effects on muscle strength and hypertrophy. METHODS: Non-resistance-trained young adults were assigned to one of the four groups: CON-ECC (n = 14), CON (n = 14) and ECC (n = 14) training groups, and a control group (n = 11) that had measurements only. The training group participants performed dominant arm elbow flexor resistance training in extended elbow joint angles (0°-50°) twice a week for 5 weeks. The total training volume (dumbbell weight × number of contractions) in CON-ECC (5745 ± 1020 kg) was double of that in CON (2930 ± 859 kg) and ECC (3035 ± 844 kg), because 3 sets of 10 contractions were performed for both directions in CON-ECC. Maximum voluntary isometric (MVC-ISO), concentric (MVC-CON), and eccentric contraction (MVC-ECC) torque of the elbow flexors and biceps brachii and brachialis muscle thickness (MT) were measured at baseline, and 3-9 days post-last training session. RESULTS: No significant changes in any measures were evident for the control group. The CON-ECC and ECC groups showed increases (P < 0.05) in MVC-ISO (12.0 ± 15.7% and 11.3 ± 10.8%, respectively) and MVC-ECC torque (12.5 ± 18.3%, 16.2 ± 11.0%) similarly. Increases in MVC-CON torque (P < 0.05) were evident for the CON-ECC (17.5 ± 13.5%), CON (10.5 ± 12.8%), and ECC (14.2 ± 10.4%) groups without a significant difference among groups. MT increased (P < 0.01) after CON-ECC (10.6 ± 5.4%) and ECC (9.7 ± 7.2%) similarly, but not significantly after CON (2.5 ± 4.8%). CONCLUSIONS: ECC training increased muscle strength and thickness similarly to CON-ECC training, despite the half training volume, suggesting that concentric contractions contributed little to the training effects.

Effects of 5-Week Foam Rolling Intervention on Range of Motion and Muscle Stiffness.

ABSTRACT: Kiyono, R, Onuma, R, Yasaka, K, Sato, S, Yahata, K, and Nakamura, M. Effects of 5-week foam rolling intervention on range of motion and muscle stiffness. J Strength Cond Res 36(7): 1890-1895, 2022-In clinical and sports settings, foam rolling (FR) intervention is widely used to increase the range of motion (ROM). However, the chronic effects of FR on ROM and muscle stiffness are unclear. The aim of this study was to investigate the effects of 5-week FR intervention on dorsiflexion ROM (DFROM) and shear elastic modulus of the medial gastrocnemius (MG) muscle. Accordingly, 30 healthy young adults were enrolled and randomly assigned to either the FR or control group with the former receiving 90 seconds of FR thrice per week over 5 weeks. Thereafter, DFROM, passive torque at DFROM, and shear elastic modulus of the MG during passive ankle dorsiflexion were assessed using a dynamometer and ultrasonography before and after 5 weeks. Our results showed that the FR group exhibited a significant increase in DFROM (Δ = 11.7%, p < 0.05, effect size = 0.39), but no changes in passive torque at DFROM, and shear elastic modulus at 0° and 10° dorsiflexion. Moreover, significant correlations were observed between change in DFROM and change in passive torque at DFROM in the FR group (rs = 0.607, p = 0.016). These results suggested that FR was an effective method to increase DFROM given its ability to change passive torque at DFROM (stretch tolerance) without altering muscle stiffness.

Comparison of the Acute Effects of Foam Rolling with High and Low Vibration Frequencies on Eccentrically Damaged Muscle.

Previous research has shown that vibration foam rolling (VFR) on damaged muscle shows greater improvement in muscle soreness and range of motion (ROM) compared with foam rolling (FR) without vibration. However, the effect of frequency in VFR on muscle soreness and loss of function caused by damaged muscles is unknown. The purpose of this study was to compare the acute effects of 90-s low-frequency (LF)- and high-frequency (HF)-VFR intervention on ROM, muscle soreness, muscle strength, and performance of eccentrically damaged muscle. Study participants were sedentary healthy adult volunteers (n = 28) who performed a bout of eccentric exercise of the knee extensors with the dominant leg and received 90-s LF-VFR or HF-VFR intervention of the quadriceps 48 h after the eccentric exercise. The dependent variables were measured before the eccentric exercise (baseline) and before (pre-intervention) and after VFR intervention (post-intervention) 48 h after the eccentric exercise. The results showed that both LF-VFR and HF-VFR similarly (p < 0.05) improved the knee flexion ROM (11.3 ± 7.2%), muscle soreness at palpation (-37.9 ± 17.2%), and countermovement jump height (12.4 ± 12.9%). It was concluded that it was not necessary to perform VFR with a high frequency to improve muscle soreness and function.

Effects of a high-volume static stretching programme on plantar-flexor muscle strength and architecture.

PURPOSE: Static stretching (SS) is performed in various settings, but there is no consensus about the effects of SS programmes on changes in muscle morphofunction. This study aimed to investigate the effects of a high-volume SS programme on muscle strength and architecture. METHODS: Sixteen healthy young male adults participated, and the dominant leg was defined as the intervention side, with the non-dominant leg as the control side. Stretching exercises were performed two times per week (6 sets of 5 min, totally 30 min per session,) for 5-week using a stretching board under the supervision of the research team. Before and after SS intervention programme, plantar-flexor strength (maximum voluntary isometric contraction, MVC-ISO; maximum voluntary concentric contraction, MVC-CON) and architecture (muscle thickness, pennation angle, and fascicle length) were measured via dynamometer and ultrasound, respectively. RESULTS: Following the SS-training programme, significant increases were observed for stretching side in MVIC-ISO at neutral ankle position (p = 0.02, d = 0.31, Δ = 6.4 ± 9.9%) and MVC-CON at 120°/s (p = 0.02, d = 0.30, Δ = 7.8 ± 9.1%), with no significant change on the control side. There was no significant change in any measure of muscle architecture for both intervention and control sides. CONCLUSION: Five-week high-volume SS induced positive changes on some measures of muscle strength but not hypertrophy of plantar-flexor muscles. Even with a volume much greater than already tested, the low strain offered by the SS per set seems be insufficient to induce architectural changes on skeletal muscle.

The Acute and Prolonged Effects of Different Durations of Foam Rolling on Range of Motion, Muscle Stiffness, and Muscle Strength.

"Foam Rolling" has been used in sports settings to increase range of motion and decrease muscle stiffness without decreasing muscle strength and athletic performance. However, there has been no study investigating the acute and prolonged effect of different durations of foam rolling intervention on muscle stiffness, and the minimum foam rolling intervention duration required to decrease muscle stiffness is unclear. Therefore, the purpose of this study was to investigate the acute and prolonged effect of different durations of foam rolling intervention on ROM, muscle stiffness, and muscle strength. The 45 participants were randomly allocated to 1 of 3 groups (30 s × 1 times group vs 30 s × 3 times group vs 30 s× 10 times group). The outcome measures were dorsiflexion range of motion, shear elastic modulus of medial gastrocnemius, and muscle strength before, 2 min and 30 min after foam rolling intervention. There were no significant differences before and 2 min after foam rolling intervention in 30 s×1 time group, whereas dorsiflexion range of motion was increased in both 30 s×3 times group (p = 0.042, d = 0.26) and 30 s× 10 times group (p < 0.01, d = 0.33). However, the increase in dorsiflexion range of motion was returned to baseline value after 30 minutes in both 30 s × 3 times group and 30 s × 10 times group. In addition, there were no significant changes in shear elastic modulus and muscle strength in all groups. This study suggested that foam rolling for more than 90 s or more of foam rolling was effective in order to increase the range of motion immediately without changing muscle stiffness and muscle strength.

Sex Differences in the Mechanical and Neurophysiological Response to Roller Massage of the Plantar Flexors.

Self-massage using foam rollers, sticks, or balls has become a popular technique to enhance joint range of motion (ROM). Although increases are reported to be larger in females than males, the mechanisms of this observation are unclear. The present study aimed to investigate the effect of roller massage (RM) on ROM, passive tissue stiffness, and neurophysiological markers as a function of sex. Males (n = 15, 22.8 ± 2.9 yrs.) and females (n = 14, 21.1 ± 0.7 yrs.) performed three 60-second bouts of calf RM. Outcomes assessed pre-, and post-intervention included passive dorsiflexion (DF) ROM, passive tissue stiffness, passive torque, DF angle at the first stretch sensation, shear elastic modulus, and spinal excitability. DF ROM (+35.9 %), passive torque at DF ROM (+46.4 %), DF angle at first stretch sensation (+32.9 %), and pain pressure threshold (+25.2 %) increased in both groups (p<.05) with no differences between males and females (p > 0.05). No changes were observed for passive stiffness, shear elastic modulus, and spinal excitability (p > 0.05). Roller massage may increase ROM independently of sex, which, in the present study, could not be ascribed to alterations in passive stiffness or neurophysiological markers. Future studies may further elucidate the role of sensory alterations as possible factors driving RM-induced changes in flexibility.

One-repetition maximum can be estimated with a handheld dynamometer and circumference in community-dwelling older adults.

[Purpose] One-repetition maximum is an essential statistic for physical therapists and coaches in rehabilitation and athletic settings. In a previous study, we showed that one-repetition maximum of the knee extensor could be predicted more accurately with the combination of maximal voluntary isometric contraction strength, as measured by a handheld dynamometer, muscle thickness, and thigh circumference, in young adults. However, there has been no study in older adults investigating the relationship between one-repetition maximum and maximal voluntary isometric contraction strength, or muscle thickness, and thigh circumference. Therefore, the aim of this study was to investigate the relationship between one-repetition maximum and maximal voluntary isometric contraction strength, or muscle thickness, and thigh circumference in older adults. [Participants and Methods] Twenty-eight older community-dwelling adults (18 males and 10 females) participated in this study. Muscle strength of the knee extensor was measured using one-repetition maximum and maximal voluntary isometric contraction strength. In addition, muscle thicknesses of the refutes femoris and the vastus intermedius, and thigh circumference were measured using ultrasonography and measuring tape, respectively. [Results] Stepwise regression analysis revealed that body mass, gender, thigh circumference at 15 cm above the patella, and maximal voluntary isometric contraction strength were significant and independent determinants (R2=0.868). [Conclusion] One-repetition maximum could be predicted more accurately using a combination of maximal voluntary isometric contraction strength, as measured with a handheld dynamometer, and thigh circumference in older adults.

Efficacies of ultrasound and a handheld dynamometer to predict one-repetition maximum.

[Purpose] It is important to accurately measure one-repetition maximum to determine the training load and number of repetitions. However, huge and expensive equipment, such as a torque machine and/or dynamometer, is needed to measure one-repetition maximum. Therefore, a more accessible and affordable method has been developed to predict one-repetition maximum. In this study, we aimed to investigate whether one-repetition maximum of the knee extensor could be predicted more accurately with a combination of muscle strength, measured using a handheld dynamometer, muscle thickness, and thigh circumference. [Participants and Methods] Participants were sixty-four non-athletic healthy adult volunteers (33 males and 31 females). Muscle strength of the knee extensor measured using one-repetition maximum, maximal voluntary isometric contraction measured using a handheld dynamometer, muscle thickness of the quadriceps and/or thigh circumference measured on ultrasonography. [Results] The stepwise regression analysis revealed that body mass, gender, muscle thickness at 15 cm above the patella, and maximal voluntary isometric contraction were the significant and independent determinants (R2=0.813). [Conclusion] One-repetition maximum could be predicted more accurately with a combination of maximal voluntary isometric contraction measured using a handheld dynamometer and muscle thickness.

The Effect of Capacitive and Resistive Electric Transfer Intervention on Delayed-Onset Muscle Soreness Induced by Eccentric Exercise.

This study aimed to investigate the acute effect of capacitive and resistive electric transfer (CRet) intervention on eccentrically damaged muscle. A total of 28 healthy and sedentary male volunteers were randomly allocated to either CRet intervention or control groups. The participants performed a bout of eccentric exercise of the knee extensors with the dominant leg and received 30 min of CRet intervention of the quadriceps 48 h after the exercise. The dependent variables for the analysis were knee flexion range of motion (ROM), muscle soreness and maximum voluntary isometric (MVC-ISO), and concentric contraction (MVC-CON) torque of the knee extensors. These were measured prior to exercise (baseline) and before and after CRet intervention (48 h after the exercise). The results showed that knee flexion ROM, muscle strength (MVC-ISO and MVC-CON), and muscle soreness significantly improved after CRet intervention. CRet intervention may improve muscle soreness and loss of muscle function in an eccentrically damaged muscle.

Relationship between Eccentric-Exercise-Induced Loss in Muscle Function to Muscle Soreness and Tissue Hardness.

It is well-known that unusual exercise, especially eccentric contraction (ECC), could cause delayed-onset muscle soreness. However, the factors related to the loss of muscle strength and range of motion (ROM) caused by eccentrically damaged muscle, such as increases in muscle soreness, tissue hardness, and pain threshold, have not been investigated in detail. Thus, this study was conducted to investigate the factors related to the loss of muscle strength and ROM caused by eccentrically damaged muscle in a large sample. Fifty-six sedentary healthy young male volunteers were instructed to perform 60 repetitions of ECC exercise. The outcome variables were measured before and 48 h after the ECC exercise. The results showed that a decrease in ROM was correlated to an increase in tissue hardness, whereas a decrease in muscle strength was correlated to an increase in muscle soreness. Our results suggested that tissue hardness must be controlled for ROM loss, and muscle soreness must be controlled for muscle-strength loss.

The Effect of Static Compression via Vibration Foam Rolling on Eccentrically Damaged Muscle.

Previous research has shown that vibration foam rolling (VFR) on damaged muscle can result in improvements in muscle soreness and range of motion (ROM). Furthermore, static compression via VFR (i.e., VFR without rolling) can increase the ROM and decrease the muscle stiffness of non-damaged muscle. Therefore, it is likely that static compression via VFR on eccentrically damaged muscle can mitigate muscle soreness and the decrease in ROM, and the decrease in muscle strength. The purpose of this study was to investigate the acute effects of a 90 s bout of VFR applied as a static compression on an eccentrically damaged quadriceps muscle, measuring ROM, muscle soreness, muscle strength, and jump performance. This study was a single-arm repeated measure design. Study participants were sedentary healthy male volunteers (n = 14, 20.4 ± 0.8 years) who had not performed habitual exercise activities or any regular resistance training for at least 6 months before the experiment. All participants performed a bout of eccentric exercise of the knee extensors with the dominant leg and then received a 90 s bout of static compression via VFR of the quadriceps 48 h after the eccentric exercise. The knee flexion ROM, muscle soreness at palpation, and countermovement jump height were measured before the eccentric exercise (baseline), before (pre-intervention) and after the VFR intervention (post-intervention), and 48 h after the eccentric exercise. The results showed that the static compression via VFR significantly (p < 0.05) improved the knee flexion ROM (6.5 ± 4.8%, d = 0.76), muscle soreness at palpation (-10.7 ± 8.6 mm, d = -0.68), and countermovement jump height (15.6 ± 16.0%, d = 0.49). Therefore, it can be concluded that static compression via VFR can improve muscle soreness and function.

Effects of stretching intensity on range of motion and muscle stiffness: A narrative review.

BACKGROUND: No review has yet investigated acute and chronic effects of different stretching intensities, including constant-angle (CA) and constant-torque (CT) stretching. OBJECTIVE: This review aimed to investigate the acute and chronic effects of different stretching intensities on the range of motion (ROM) and passive properties. METHODS: PubMed, Scopus, and Google Scholar were used for literature search. Advanced search functions were used to identify original studies using the terms stretching intensity, constant-torque stretching, constant-angle stretching, ROM, passive stiffness, shear elastic modulus in the title or abstract. The keywords were combined using the Boolean operators "AND" and "OR". The search for articles published from inception until 2021 was done in electronic databases. RESULTS AND CONCLUSION: Five studies compared CA and CT stretching. Three studies reported a greater decrease in passive stiffness, and two studies reported a greater ROM increase after CT than CA stretching. Twelve studies investigated the acute effects of different stretching intensities, and six reported a greater ROM increase at higher stretching intensities. Five studies reported a greater decrease in passive stiffness at higher stretching intensities, but three reported no significant differences in passive stiffness among stretching intensities. Five studies investigated the chronic effect, and four reported no significant difference in ROM change among different intensities. Three studies reported no significant changes in passive stiffness after the stretching program. We suggest that the acute effect of higher stretching intensity, including CT stretching, was more effective for changes in ROM and passive stiffness, but the chronic effect was weak.

Cross-education effect of 4-week high- or low-intensity static stretching intervention programs on passive properties of plantar flexors.

This study aimed to compare the cross-education effect of unilateral stretching intervention programs with two different intensities (high- vs. low-intensity) on dorsiflexion range of motion (DF ROM), muscle stiffness, and muscle architecture following a 4-week stretching intervention. Twenty-eight healthy males were randomly allocated into two groups: a high-intensity static stretching (HI-SS) intervention group (n = 14; stretch intensity 6-7 out of 10) and a low-intensity static stretching (LI-SS) intervention group (n = 14; stretch intensity 0-1 out of 10). The participants were asked to stretch their dominant leg (prefer to kick a ball) for 4 weeks (3 × week for 3 × 60 s). Before and after the intervention, the non-trained leg passive properties (DF ROM, passive torque, and muscle stiffness) of the plantar flexors and the muscle architecture of the gastrocnemius medialis (muscle thickness, pennation angle, and fascicle length) were measured. Non-trained DF ROM and passive torque at DF ROM were significantly increased in the HI-SS group (p < 0.01, d = 0.64, 50.6%, and p = 0.044, d = 0.36, 18.2%, respectively), but not in the LI-SS group. Moreover, there were no significant changes in muscle stiffness and muscle architecture in both groups. For rehabilitation settings, a high-intensity SS intervention is required to increase the DF ROM of the non-trained limb. However, the increases in DF ROM seem to be related to changes in stretch tolerance and not to changes in muscle architecture or muscle stiffness.

The Associations between Rapid Strength Development and Muscle Stiffness in Older Population.

BACKGROUND: Previous studies suggest that the capacity for rapid force production of ankle plantar flexors is essential for the prevention of falls in the elderly. In healthy young adults, there were significant associations between rate of force development and muscle stiffness measured by shear wave elastography. However, there has been no study investigating the association of rate of force development with shear elastic modulus in older adults. METHODS: The muscle strength and shear elastic modulus of the medial gastrocnemius muscle in both legs were measured in 17 elderly men and 10 elderly women (mean ± SD; 70.7 ± 4.1 years; 160.6 ± 8.0 cm; 58.7 ± 9.5 kg). We investigated the rate of force development of plantar flexors and shear elastic modulus of medial gastrocnemius muscle using by shear wave elastography. RESULTS: Our results showed that there were no significant associations between normalized rate of force development and shear elastic modulus of medial gastrocnemius muscle. CONCLUSION: This suggests that the capacity of rapid force production could be related not to muscle stiffness of the medial gastrocnemius muscle, but to neuromuscular function in older individuals.

Cross-education and detraining effects of eccentric vs. concentric resistance training of the elbow flexors.

BACKGROUND: Unilateral resistance training increases the strength of the contralateral non-trained homologous muscles known as the cross-education effect. We tested the hypothesis that unilateral eccentric resistance training (ET) would induce greater and longer-lasting cross-education effect when compared with concentric resistance training (CT). METHODS: Young (20-23 y) participants were allocated to ET (5 males, 4 females) or CT (5 males, 4 females) group that performed unilateral progressive ET or CT of the elbow flexors, twice a week for 5 weeks (10 sessions) followed by a 5-week detraining, and control group (7 males, 6 females) that did not perform any training. Maximum voluntary isometric contraction torque of the elbow flexors (MVIC), one-repetition maximum of concentric dumbbell curl (1-RM), and biceps brachii and brachialis muscle thickness (MT) were measured from the trained and non-trained arms before, several days after the last training session, and 5 weeks later. A ratio between the trained and non-trained arms for the change in MVIC or 1-RM from pre- to post-training (cross-body transfer ratio) was compared between ET and CT groups. RESULTS: The control group did not show significant changes in any variables. Both ET and CT increased (P < 0.05) MVIC (22.5 ± 12.3 % vs. 26.0 ± 11.9 %) and 1-RM (28.8 ± 6.6 % vs. 35.4 ± 12.9 %) of the trained arm without a significant difference between groups. MVIC was maintained after detraining for ET but returned to the baseline for CT, and 1-RM was maintained after detraining for both ET and CT. For the non-trained arm, MVIC (22.7 ± 17.9 % vs. 12.2 ± 10.2 %) and 1-RM (19.9 ± 14.6 % vs. 24.0 ± 10.6 %) increased similarly (P > 0.05) after ET and CT, and MVIC returned to the baseline after detraining, but 1-RM was maintained for both groups. An increase (P < 0.05) in MT was found only after ET for the trained arm (7.1 ± 6.1 %). The cross-body transfer ratio for MVIC was greater (P < 0.05) for ET (90.9 ± 46.7 %) than CT (49.0 ± 30.0 %). CONCLUSIONS: These results did not support the hypothesis and showed similar changes in the most of the variables between ET and CT for the trained and non-trained arms, and strong cross-education effects on MVIC and 1-RM, but less detraining effect after ET than CT on MVIC of the trained arm. TRIAL REGISTRATION: University Hospital Medical Information Network Clinical Trials Registry (UMIN000044477; Jun 09, 2021).

Comparison of the Acute Effects of Hold-Relax and Static Stretching among Older Adults.

Various stretching techniques are generally recommended to counteract age-related declines in range of motion (ROM) and/or increased muscle stiffness. However, to date, an effective stretching technique has not yet been established for older adults. Consequently, we compared the acute effects of hold relax stretching (HRS) and static stretching (SS) on dorsiflexion (DF) ROM and muscle stiffness among older adults. Overall, 15 elderly men and nine elderly women (70.2 ± 3.9 years, 160.8 ± 7.8 cm, 59.6 ± 9.7 kg) were enrolled, and both legs were randomized to either HRS or SS stretching. We measured DF ROM and muscle stiffness using a dynamometer and ultrasonography before and after 120 s of HRS or SS interventions. Our multivariate analysis indicated no significant interaction effects, but a main effect for DF ROM. Post-hoc tests revealed that DF ROM was increased after both HRS and SS interventions. Moreover, multivariate analysis showed a significant interaction effect for muscle stiffness. Post-hoc tests revealed that muscle stiffness was decreased significantly after only SS intervention. Taken together, our results indicated that both HRS and SS interventions are recommended to increase ROM, and SS is recommended to decrease muscle stiffness in older adults.

Acute Effect of Vibration Roller With and Without Rolling on Various Parts of the Plantar Flexor Muscle.

A single use of a vibration foam roller likely increases the range of motion (ROM) without decreasing muscle strength and athletic performance. However, to date, no study compared the effects of a vibration roller with and without rolling on various parts of the plantar flexor muscle. Therefore, this study aimed to compare the effects of the vibration foam roller with rolling or without rolling at the muscle-tendon junction (MTJ) or the muscle belly on dorsiflexion (DF) ROM, passive torque at DF ROM, shear elastic modulus, muscle strength, and jump performance. Fifteen healthy young males performed the following three conditions: (1) vibration rolling over the whole muscle-tendon unit, (2) static vibration on muscle belly, and (3) static vibration on MTJ for three-set 60-s vibration in random order. In this study, DF ROM, passive torque, shear elastic modulus, muscle strength, and single-leg drop jump were measured before and immediately after the interventions. The DF ROM and passive torque at DF ROM were increased after all three conditions, whereas the shear elastic modulus was decreased after vibration rolling and static vibration on the muscle belly, but not following static vibration of the MTJ. In addition, there were no significant changes in muscle strength and jump performance in any group. Our results showed that vibration with rolling or static vibration on muscle belly could be effective to improve ROM and muscle stiffness without adverse effects of muscle strength and athletic performance.