Acute effects of 5 min of plantar flexor static stretching on balance and gait in the elderly

Plantar flexor muscle stretching depresses the soleus late response but not tendon tap reflexes

The purpose of this study was to investigate changes in muscle spindle sensitivity with early and late soleus reflex responses via tendon taps and transcranial magnetic stimulation, respectively, after an acute bout of prolonged static plantar flexor muscle stretching. Seventeen healthy males were tested before and after 5 min (5 × 60-s stretches) of passive static stretching of the plantar flexor muscles. Maximal voluntary isometric torque and M wave-normalized triceps surae muscle surface electromyographic activity were recorded. Both soleus tendon reflexes, evoked by percussion of the Achilles tendon during rest and transcranial magnetic stimulation-evoked soleus late responses during submaximal isometric dorsiflexion were also quantified. Significant decreases in maximal voluntary isometric plantar flexion torque (-19.2 ± 13.6%, p = .002) and soleus electromyographic activity (-20.1 ± 11.4%, p < .001) were observed immediately after stretching, and these changes were highly correlated (r = 0.76, p < .001). No changes were observed in tendon reflex amplitude or latency or peak muscle twitch torque (p > .05). Significant reductions in soleus late response amplitudes (-46.9 ± 36.0%, p = .002) were detected, although these changes were not correlated with changes in maximal electromyographic activity, torque or tendon reflex amplitudes. No changes in soleus late response latency were detected. In conclusion, impaired neural drive was implicated in the stretch-induced force loss; however, no evidence was found that this loss was related to changes in muscle spindle sensitivity. We hypothesize that the decrease in soleus late response indicates a stretch-induced reduction in a polysynaptic postural reflex rather than spindle reflex sensitivity.

Lack of cortical or Ia-afferent spinal pathway involvement in muscle force loss after passive static stretching

This study investigated whether modulation of corticospinal-motoneuronal excitability and/or synaptic transmission of the Ia afferent spinal reflex contributes to decreases in voluntary activation and muscular force after an acute bout of prolonged static muscle stretching. Fifteen men performed five 60-s constant-torque stretches (15-s rest intervals; total duration 5 min) of the plantar flexors on an isokinetic dynamometer and a nonstretching control condition in random order on 2 separate days. Maximum isometric plantar flexor torque and triceps surae muscle electromyographic activity (normalized to M wave; EMG/M) were simultaneously recorded immediately before and after each condition. Motor-evoked potentials (using transcranial magnetic stimulation) and H-reflexes were recorded from soleus during EMG-controlled submaximal contractions (23.4 ± 6.9% EMG maximum). No changes were detected in the control condition. After stretching, however, peak torque (mean ± SD; -14.3 ± 7.0%) and soleus EMG/M (-17.8 ± 6.2%) decreased, and these changes were highly correlated (r = 0.83). No changes were observed after stretching in soleus MEP or H-reflex amplitudes measured during submaximal contractions, and interindividual variability of changes was not correlated with changes in EMG activity or maximum torque. During EMG-controlled submaximal contractions, torque production was significantly decreased after stretching (-22.7 ± 15.0%), indicating a compromised muscular output. These data provide support that changes in the excitability of the corticospinal-motoneuronal and Ia afferent spinal reflex pathways do not contribute to poststretch neural impairment.NEW & NOTEWORTHY This study is the first to specifically examine potential sites underlying the decreases in neural activation of muscle and force production after a bout of muscle stretching. However, no changes were found in either the H-reflex or motor-evoked potential amplitude during submaximal contractions.

Combined Resistance and Stretching Exercise Training Benefits Stair Descent Biomechanics in Older Adults

Introduction

Stair descent is a physically demanding activity of daily life and common risk for falls. Age-related deteriorations in ankle joint capacities make stair descent particularly challenging for older adults in built environments, where larger rise steps are encountered. Exercise training may allow older adults to safely cope with the high biomechanical demands of stair descent. However, little is known about the demands of increased rise stairs for older adults, nor the impact of exercise.

Aim

We investigated whether the effects of lower-limb resistance training would alter joint kinetics and movement strategies for older adults when descending standard rise, and increased rise stairs.

Methods

Fifteen older adults descended a four-step stair adjusted to standard rise (170 mm), and increased rise (255 mm) on separate visits. Between these two visits, randomly allocated participants underwent 16 weeks of either: resistance exercise training (n = 8) or habitual activity (n = 7). Kinetic data were measured from step-mounted force plates, and kinematic data from motion-capture cameras. Training involved twice-weekly sessions of lower-limb resistance exercises (three sets of ∼8 repetitions at ∼80% three-repetition maximum), and static plantarflexor stretching (three, 45 s holds per leg).

Results

Standard stairs – Peak ankle joint moments increased (p < 0.002) and knee joint moments decreased (p < 0.01) during descent after exercise training. Peak centre of pressure-centre of mass (CoP-CoM) separations increased in posterior (p = 0.005) and medio-lateral directions (p = 0.04) after exercise training. Exercise training did not affect CoM descent velocity or acceleration. Increased rise stairs – Required greater ankle, knee, and hip moments (p < 0.001), peak downward CoM velocity and acceleration (p = 0.0001), and anterior-posterior CoP-CoM separation (p = 0.0001), but lower medial-lateral CoP-CoM separation (p < 0.05), when compared to standard stair descent. Exercise training did not affect joint kinetics or movement strategies.

Discussion

Exercise training increased the maximum joint ROM, strength and force production of the ankle, and enabled a greater ankle joint moment to be produced in single-leg support (lowering phase) during standard stair descent. Descending increased rise stairs raised the task demand; exercise training could not overcome this. Future research should prioritize the ankle joint in stair descent, particularly targeting plantarflexor torque development across stairs of varying riser heights.

Acute effects of contract-relax proprioceptive neuromuscular facilitation stretching of hip abductors and adductors on dynamic balance

Background

Balance control has been shown to play a fundamental role both in everyday life and many athletic activities. An important component of balance control is the somatosensory information gained from muscle spindles and Golgi tendon organs. The changes in the muscle-tendon unit stiffness could alter the ability to detect and respond promptly to changes of an unstable environment. One of the procedures affecting muscle stiffness is stretching, and contract-relax PNF stretching (CRS) is considered as one of the safest and most effective techniques. So far, there are no studies on the impact of CRS of hip adductor and abductor muscles on body balance. These muscle groups are responsible for maintaining mediolateral balance which is of particular interest, since it is more affected by ageing and disease and since its deterioration has been associated with an increased risk of falling. In light of the above, the aim of the present study was to investigate the effects of a single dose of contract-relax proprioceptive neuromuscular facilitation stretching of hip adductors and abductors on mediolateral dynamic balance.

Methods

The study involved 45 healthy individuals (age 19–23 years) assigned to the intervention group (IG) or the control group (CG). Balance testing was carried out before (Pre) and immediately after CRS in the intervention group or after 5-minute rest in the control group (Post). There were performed three repetitions of the CRS targeting the adductor and abductor muscles of the hip.

Results

Statistically significant differences between Pre and Post condition were observed only in the intervention group. The values of all measured variables defining the body’s dynamic balance were significantly lower immediately after the applied CRS, which indicates an improved body balance: Global Index (p = 0.0001), total area of sway (p = 0.0001), external area of sway (p = 0.00004), external time (p = 0.0004) and reaction time (p = 0.0003).

Conclusions

A single dose of contract-relax proprioceptive neuromuscular facilitation stretching of the hip adductor and abductor muscles improved mediolateral dynamic balance.

Effect of Ankle Range of Motion (ROM) and Lower-Extremity Muscle Strength on Static Balance Control Ability in Young Adults: A Regression Analysis

Background

The purpose of this study was to investigate the effect of ankle ROM and lower-extremity muscle strength on static balance control ability in young adults.

Material/Methods

This study was conducted with 65 young adults, but 10 young adults dropped out during the measurement, so 55 young adults (male: 19, female: 36) completed the study. Postural sway (length and velocity) was measured with eyes open and closed, and ankle ROM (AROM and PROM of dorsiflexion and plantarflexion) and lower-extremity muscle strength (flexor and extensor of hip, knee, and ankle joint) were measured. Pearson correlation coefficient was used to examine the correlation between variables and static balance ability. Simple linear regression analysis and multiple linear regression analysis were used to examine the effect of variables on static balance ability.

Results

In correlation analysis, plantarflexion ROM (AROM and PROM) and lower-extremity muscle strength (except hip extensor) were significantly correlated with postural sway (p<0.05).

In simple correlation analysis, all variables that passed the correlation analysis procedure had significant influence (p<0.05). In multiple linear regression analysis, plantar flexion PROM with eyes open significantly influenced sway length (B=0.681) and sway velocity (B=0.011).

Conclusions

Lower-extremity muscle strength and ankle plantarflexion ROM influenced static balance control ability, with ankle plantarflexion PROM showing the greatest influence. Therefore, both contractile structures and non-contractile structures should be of interest when considering static balance control ability improvement.

Acute effects of static stretching on passive stiffness and postural balance in healthy, elderly men

OBJECTIVES

This study aimed to examine the acute effects of straight-leg raise (SLR) static stretching on passive stiffness and postural balance in healthy, elderly men. An additional aim of this study was to examine the relationships between stiffness and balance at baseline (prior to stretching) and the relationships between the stretch-induced changes in these variables.

METHODS

Eleven elderly men (age = 69 ± 6 years; height = 177 ± 7 cm; mass = 83 ± 13 kg) underwent postural balance and passive stiffness assessments before and after: 1) a stretching treatment consisting of four, 15-s SLR static stretches performed by the primary investigator and 2) a control treatment consisting of no static stretching. Passive stiffness was calculated from the slopes of the initial (phase 1) and final (phase 2) portions of the angle-torque curve. Unilateral postural balance was assessed on the right leg using a commercially designed balance testing device, which provides a measurement of static stability based on the overall stability index (OSI).

RESULTS

The slope coefficients and OSI values decreased from pre- to post-treatment for the stretching intervention (P = 0.015 and 0.018, respectively); however, there were no changes for the control (P = 0.654 and 0.920). For the stretching intervention, a significant positive relationship was observed between OSI and the slope coefficient of phase 1 at baseline (r = 0.619; P = 0.042). A significant positive relationship was also observed between the stretched-induced changes in OSI and the slope coefficient of phase 1 (r = 0.731; P = 0.011). No relationship was observed between OSI and the slope coefficient of phase 2 at baseline (r = 0.262; P = 0.437) nor was there a relationship between the changes in these variables (r = 0.419; P = 0.200).

CONCLUSION

A short, practical bout of SLR static stretching may be an effective intervention for reducing passive stiffness and improving postural balance in healthy, elderly men.

Effects of ankle plantar flexors stretching with closed kinetic chain on pelvic movements and gait speed in hemiplegia patients: a case study

[Purpose] The purpose of this study was to identify the effects of ankle plantar flexors stretching with closed kinetic chain (CKC) in hemiplegia patients. [Methods] This study used a reversal design (A-B-A’) for a stroke with hemiplagia. The intervention program consisted of 30 min sessions, once a day, for 15 days. The subjects were trained for 15 sessions in total. Pelvic movements (anterior ·posterior tilting, elevation, depression, forward·backward rotation) during walking and gait speed were measured in hemiplegia patients. [Results] Overall, the angle of pelvic movements was increased in Treatment and, Baseline II compared with Baseline I. The gait speed was maximally increased in Baseline II, followed by Treatment and Baseline I. [Conclusion] These results suggest that ankle plantar flexors stretching with closed kinetic chain had a positive effect on pelvic movements and gait speed in hemiplegia patients. Also, after treatment, its effect on gait of hemiplegia patients was maintained.

Analysis of the correlation between the differences in muscle strengths between the bilateral lower extremities and postural stability in healthy adults

[Purpose] The purpose of this study was to examine the correlation between the differences in muscle strengths between the bilateral lower extremities and the level of postural sway that indicates postural stability. [Subjects and Methods] A total of 49 students (18 males and 31 females) at Y University in Gyeongsangnam-do, South Korea, participated in this study. Partial correlation analysis was performed to determine the effects of sway length and velocity on the differences in muscle strengths between the lower extremities. [Results] Both sway length and sway velocity showed a negative correlation with the difference in bilateral ankle dorsiflexion strength. Both sway length and sway velocity showed a positive correlation with the difference in bilateral hip flexion strength. [Conclusion] Difference in left-right muscle strengths of hip flexion and ankle dorsiflexion can affect postural stability when the levels of lower extremity muscle strengths are excluded.

The intra- and inter-rater reliabilities of the Short Form Berg Balance Scale in institutionalized elderly people

[Purpose] The purpose of this study was to examine the intra- and inter-rater reliabilities of the Short Form Berg Balance Scale in institutionalized elderly people. [Subjects and Methods] A total of 30 elderly people in a nursing facility in Y city, South Korea, participated in this study. Two examiners administered the Short Form Berg Balance Scale to one subject to investigate inter-rater reliability. After a week, the same examiners administered the Short Form Berg Balance Scale once more to investigate intra-rater reliability. [Results] The intra-rater reliability was 0.83. The inter-rater reliability was 0.79. Both reliabilities were high (more than 0.7). [Conclusion] The Short Form Berg Balance Scale is a version of the Berg Balance Scale shortened by reducing the number of items, but its reliabilities were not lower than those of the Berg Balance Scale. The Short Form Berg Balance Scale can be useful clinically due to its short measurement time.

The effects of virtual reality game exercise on balance and gait of the elderly

[Purpose] The aim of this study was to examine the effects of ball exercise as a general exercise on the balance abilities of elderly individuals by comparing ball exercise with virtual reality exercise. [Subjects and Methods] Thirty elderly individuals residing in communities were randomly divided into a virtual reality game group and a ball exercise group and conducted exercise for 30 min 3 times a week for 8 weeks. [Results] Step length increased significantly, and the average sway speed and Timed Up and Go time significantly decreased in both groups. A comparison of sway length after the intervention between the two groups revealed that the virtual reality game exercise resulted in a reduction than the ball exercise. [Conclusion] The results of this study indicated that the virtual reality game exercise may improve balance and gait of elderly individuals in communities.

Effects of self stretching on pain and musculoskeletal symptom of bus drivers

[Purpose] The aim of this study was to evaluate the musculoskeletal symptoms, pain and risk of postures as well as the effects of stretching exercise on the work-related symptoms and pain of bus drivers. [Subjects and Methods] Eighty-one drivers were randomly recruited from a bus corporation for this study. Information about pain levels, painful regions, and general characteristics of subjects was obtained using the symptom research form (KOSHA Code H-30-2003). The level of pain was assessed on a scale of numeric rating scale (NRS) which is divided by 10. Ergonomic posture assessment was conducted using the rapid upper limb assessment (RULA). Self-stretching exercise was performed for 4 weeks by the bus drivers who suffered from neck and shoulder pain. [Results] Musculoskeletal symptoms were present in the order of shoulder, neck, lower back and lower extremities. Compared with other jobs, the final score, and the action level of bus drivers were very high, showing 57.6% of action levels 3 and 4. A statistically significant decrease of pain was shown after the self-stretching intervention. There was also a significant decrease of musculoskeletal symptoms in the neck and shoulders after the self-stretching exercise. [Conclusion] Performing stretching for musculoskeletal symptoms had a positive influence on the symptoms and reduced pain.

The effect of increase in baggage weight on elderly women's lower extremity muscle activation during gait

The aim of the present study was to examine the effect of increased baggage weight on the muscle activation of elderly women's lower extremities during gait. A total of 24 elderly women who were residing in communities in Daegu, South Korea aged 79.6±6.2, 149.7±7.0cm in height, and 53.5±7.2kg in weight participated in this study. The muscle activation of each muscle was measured three times at 2kg, 3kg, and 4kg of baggage weight while the subjects were conducting treadmill walking wearing backpacks. Electrodes were placed on four muscles: the quadriceps muscle (rectus femoris), the hamstring muscle (semitendinosus), the tibialis anterior muscle, and the soleus muscle. The results show that the rates of increase in muscle activation in the tibialis anterior and soleus muscles according to baggage weight increase were higher than those in the quadriceps and hamstring muscles (<0.05). These results indicate that the heavier weight loads increase the activation of muscles that control the ankle joints causing muscle fatigue. Moreover, a decrease in balance ability through muscle fatigue can be a risk factor for falls. Thus, elderly people should be instructed not to carry heavy objects.