Effects of a single-session stance-slip perturbation training program on reducing risk of slip-related falls

The purpose of this pilot study was to establish the efficacy and feasibility of a single-session treadmill-based stance-slip perturbation program on preventing slip-related falls while walking over the ground among young adults. Two groups (training vs. control) of healthy young participants were respectively exposed to a treadmill-based stance-slip perturbation training protocol and a placebo training protocol. Post training, both groups experienced an unexpected overground gait-slip. Our results indicated that 28.6% of individuals in the training group and 55.0% of controls fell when responding to the overground slip. In comparison with the control group, the training group exhibited better control over the compensatory step and dynamic stability at the instant immediately prior to recovery touchdown. The improved dynamic stability control in the training group likely resulted from the enhanced capability of harnessing the slip kinematics of the base of support. Dynamic stability did not display any significant group-associated difference at slipping foot touchdown and recovery foot liftoff. This implies that a stance-slip perturbation training protocol with eight slips may not provide enough and very task-specific incentive to the Central Nervous System to form the capability of sufficiently modifying regular gait pattern after an unexpected gait slip. However, given its ease of use, stance-perturbation could be a practical option to train individuals in clinical settings as a simple push or pull could exert a perturbation to a standing individual. The findings from this study provide information for developing future studies based on large-scale samples.     

Effects of obesity on dynamic stability control during recovery from a treadmill-induced slip among young adults

This study sought to investigate the effects of obesity on falls and dynamic stability control in young adults when subject to a standardized treadmill-induced gait-slip. Forty-four young adults (21 normal-weight and 23 obese) participated in this study. After their muscle strength was assessed at the right knee under maximum voluntary isometric (flexion and extension) contractions, participants were moved to an ActiveStep treadmill. Following 5 normal walking trials on the treadmill, all participants encountered an identical and unexpected slip defined as a perturbation in the anterior direction with the magnitude of 24-cm slip distance and 2.4-m/s peak slip velocity. The trials were categorized as a fall or recovery based on the reliance of the subject on external support following the slip. Compared with the normal-weight group, the obese group demonstrated less relative muscle strength and fell more responding to the slip (78.3% vs. 40.0%, p=0.009). After adjusting the body height and gender, the results indicated that the obese group was 19.1-time (95% confidence interval: [2.06, 177.36]) more prone to a fall than the normal-weight group when experiencing the same treadmill-induced slip. The obese group showed significantly impaired dynamic stability after slip possibly due to the inability of controlling the trunk segment׳s backward lean movement. Obesity measurements explained more slip outcome variance than did the strength measurements (53.4% vs. 18.1%). This study indicates that obesity most likely influences the ability to recover from slip perturbations. It is important to develop interventions to improve the capability of balance recovery among individuals with obesity.     

Reduced intensity in gait-slip training can still improve stability

Perturbation training with “free” slips (i.e., with long slip distance) has been able to successfully improve stability and to reduce the incidence of falls among older adults. Yet, it is unclear whether a highly constrained training with reduced slip distance (and hence training intensity) can achieve similar effects. The purpose of this study was to investigate whether short-distance slips could also improve the control of stability, and whether such improvements could be generalized to a novel, “free” slip. Thirty-six young subjects were randomly assigned to either one of the two training groups, which underwent seven training trials with constrained slips of either 12-cm or 18-cm in distance before encountering a novel, “free” slip (up to 150 cm) in the test trial; or the control group, which only experienced the same test trial of a novel, “free” slip. The results showed that while both training groups were able to significantly improve their control of stability in training; the 18-cm group had significantly better reactive control of stability than the 12-cm group. During the “free” slip, such advantage enabled the 18-cm group to exhibit significantly less balance loss incidence than 12-cm group (58.3 vs. 83.3%) and the controls (100%). These differences could be fully accounted for when we assume that the central nervous system directly controls slip velocity or slip distance during adaptation, whereby the level of similarity between training trials and the test trial governs the degree of generalization. The findings that low intensity training may still improve stability warrant further investigations among older adults.     

Effects of neck muscle training in women with chronic neck pain: one-year follow-up study

Exercises are commonly recommended for chronic neck pain, but evidence-based guidelines do not explain what types of exercise. The aim of this randomized study was to evaluate the rate of change in neck strength following high- and low-intensity neck muscle training and their effects on pain and disability. One hundred eighty women with chronic neck pain were randomized into a high-intensity strength training group (STG), local muscle endurance training group (ETG), or control group (CG). The neck training consisted of isometric exercises in the STG and dynamic exercises in the ETG. Both groups performed dynamic exercises for the upper extremities. Strength tests, neck pain, and disability indices were evaluated at the baseline, at the follow-ups after 2 and 6 months in the training groups, and after 12 months in all groups. In both groups the greatest gains in neck strength, as well as decrease in neck pain and disability, were achieved during the first 2 months. However, the improvements continued up to 12 months. The STG achieved the greatest strength gains at all follow-ups. The CG showed only minor changes, and significant differences were found in favor of the training groups in all measures. The change in neck pain and disability indices correlated with the isometric neck strength (r = -0.22 [-0.36 to - 0.08] to -0.36 [-0.49 to -0.23]). Neck and shoulder muscle training was shown to be an effective therapy for chronic neck pain, resulting in early improvement in both the strength tests and subjective measures. The results can be maintained and even improved with long-term training.     

The adaptations in muscle architecture following whole body vibration training

Objective:This study aims to investigate the effect of 8-week whole-body vibration (WBV) added to conventional training on muscular architecture, dynamic muscle strength and physical performance compared to controls in young basketball players.Methods:Sixteen young basketball players between the ages of 14-16 years were randomly assigned to whole body vibration group (VG) or control group (CG). Both groups were trained with a conventional program. Pennation angle (PeA), fascicle length and muscle thickness of Rectus Femoris (RF) and Vastus lateralis were measured by ultrasonography. Isokinetic dynamic muscle testing at 180 °/s and 60°/s, squat jump (SJ) and flexibility were evaluated before and after 8 weeks of training programs. Primary outcome measure was the fascicle length.Results:Fascicle length of RF, SJ height and flexibility increased significantly within VG compared to pretraining (p<0.05). SJ height increased in VG compared to CG significantly following training (p<0.05). PeA, fascicle length, muscle thicknesses, strength and flexibility did not differ between groups.Conclusion:Eight weeks of WBV training improved fascicle length of RF, SJ height, and flexibility compared to pre-training. Addition of WBV to conventional training did not cause improvement in muscle architecture, strength and flexibility compared to conventional training alone.     

应用振动训练可修复小鼠肌肉疲劳损伤

为探讨不同强度全身振动训练对于生物体运动表现、运动疲劳以及生理生化反应的影响。本研究使用4周大雄性C57BL/6J小鼠为模型,随机分作3组,每组8只动物:无振动训练对照组(sedentary control,SC);相对较低强度振动训练组(5.6 Hz/0.13 g; relative low-intensity vibration, LV);相对较高强度振动训练组(13 Hz/0.68 g; relative high-intensity vibration, HV)。振动训练以每天振动15 min,每周5次,为期4周,随后进行各项测试包括:前肢抓力、衰竭性耐力运动测验、疲劳生化指标分析、临床血液生化检测以及病理组织切片观察。数据以单因素方差进行分析,并以Duncan's test检验不同的组间是否存在显著差异。两组接受振动训练介入的小鼠比对照组,具有显著提升肌力和衰竭性耐力运动的时间。在疲劳与肌肉损伤相关生化指标部分,振动训练具有明显降低单次运动测试后血氨与血乳酸浓度以及肌酸激酶活性上升的作用。在临床血液生化方面,4周振动训练显著降低草醋酸转胺酶、麸丙酮酸转胺酶与肌酸激酶活性,以及尿素氮浓度。本研究证实振动训练4周的连续介入下,具有提升运动表现与抗疲劳的作用,而且不会造成健康小鼠在生理生化以及病理上的副作用。在提供一般健康成人的运动训练指导上,全身振动训练具有健康促进的应用性。     

Exercise of mechanisms for dynamic stability control increases stability performance in the elderly

Old adults show a decreased recovery performance compared to young ones after unexpected perturbations increasing the risk of falls. Therefore, the purpose of the present study was to examine the effect of a specific training of mechanisms responsible for dynamic stability on the recovery performance of old adults after simulated forward falls and the contribution of muscle strength exercise. 38 old adults (two experimental groups each n=13 and a control group, n=12) participated in the study. Group 1 exercised the mechanisms responsible for dynamic stability like increase in base of support and counter-rotating segments around the centre of mass by practicing specific tasks including these mechanisms. Group 2 exercised these mechanisms of dynamic stability and muscle strength. The exercise volume was equal in both interventions (14 weeks, two times per week and ～1.5 h per session). Stability performance has been examined by simulated forward falls before and after the intervention. The two experimental groups improved in a similar extent (～35%) their ability to regain balance during forward falls after the intervention. The reason was a faster increase in base of support. Further, the performance enhancement was related to an increase in the rate of hip moment generation. Exercising the mechanisms responsible for dynamic stability control in old adults affects their ability to regain balance after forward falls. A faster utilization of these mechanisms due to improved neuromuscular coordination resulted in the significant performance enhancement.     

Can treadmill-slip perturbation training reduce immediate risk of over-ground-slip induced fall among community-dwelling older adults?

The purpose of this study was to determine any potential falls-resistance benefits that might arise from treadmill-slip-perturbation training. One hundred sixty-six healthy community-dwelling older adults were randomly assigned to either the treadmill-slip-training group (Tt) or the treadmill-control group (Tc). Tt received 40 slip-like perturbations during treadmill walking. Tc received unperturbed treadmill walking for 30 min. Following their treadmill session, both groups were exposed to a novel slip during over-ground walking. Their responses to this novel slip were also compared to previously collected data from participants who received either over-ground-slip training (Ot) with 24 slips or over-ground walking (Oc) with no training before experiencing their novel over-ground slip. Fall rates and both proactive (pre-slip) and reactive (post-slip) stability were assessed and compared for the novel over-ground slip in groups Tt, Tc, and Oc, as well as for the 24th slip in Ot. Results showed Tt had fewer falls than Tc (9.6% versus 43.8%, p < 0.001) but more falls than Ot (9.6% versus 0%, p < 0.001). Tt also had greater proactive and reactive stability than Tc (Tt > Tc, p < 0.01), however, Tt’s stabilities were lower than those of Ot (p < 0.01). There was no difference in fall-rate or reactive stability between Tc and Oc, though treadmill walking did improve the proactive stability control of the latter. While the treadmill-slip-training protocol could immediately reduce the numbers of falls from a novel laboratory-reproduced slip, such improvements were far less than that from the motor adaptation to the over-ground-slip-training protocol.     

Effects of mechanical vibration applied in the opposite direction of muscle shortening on maximal isometric strength

Most studies about human responses to mechanical vibrations involve whole-body vibration and vibration applied perpendicularly to the tendon or muscle. The aim of the present study was to verify the effects of mechanical vibration applied in the opposite direction of muscle shortening on maximal isometric strength of the flexor muscles of the elbow due to neural factors. Conventional isometric training with maximal isometric contractions (MVCs) and isometric training with vibrations were compared. Nineteen untrained males, ages 24 +/- 3.28 years, were divided into 2 training groups. Group 1 performed conventional isometric training and group 2 isometric training with mechanical vibrations (frequency of 8 Hz and amplitude of 6 mm). Both groups executed 12 MVCs with a duration of 6 seconds and 2-minute intervals between the repetitions. The subjects trained 3 times per week for 4 weeks. The strength of the group subjected to vibrations increased significantly by 26 +/- 11% (p < 0.05), whereas the strength of the group with conventional isometric training increased only 10 +/- 5% (p < 0.05). These data suggest that training with vibrations applied in the opposite direction of muscle shortening enhances the mechanism of involuntary control of muscle activity and may improve strength in untrained males. Since these findings were in untrained males, further studies with athletes are necessary in order to generalize the results to athletes' training, although it seems that it would be possible.     

Deficits in the way to achieve balance related to mechanisms of dynamic stability control in the elderly

The purpose of this study was to examine the postural corrections related to components of dynamic stability aimed to increase our understanding of successful postural control among the elderly population. This was done by comparing balance behaviour of older adults who were able to recover stability (stable) and others who failed to regain stability (unstable) with a single step after a forward fall. Thirty-eight old male adults (64+/-3yr, 176+/-6cm, 78.5+/-7.8kg) had to recover balance after a sudden induced forward fall. All participants performed maximal isometric ankle plantarflexion and knee extension contractions on a dynamometer. The elongation of the gastrocnemius medialis and the vastus lateralis tendon and aponeuroses during isometric contraction was examined by ultrasonography. There were no differences in leg-extensor muscle strength or tendon stiffness between the two groups showing that the muscle tendon capacities may not be the reason for the observed differences in dynamic stability control. The unstable participants created a higher horizontal ground reaction push-off force of the support limb in the second part ( approximately 260ms after release) of the phase until touchdown leading to an unstable body position at touchdown. The results indicate deficits in the way to achieve balance related to mechanisms responsible for dynamic stability control within the elderly population.     

Creatine Supplementation Associated or Not with Strength Training upon Emotional and Cognitive Measures in Older Women: A Randomized Double-Blind Study

Purpose

To assess the effects of creatine supplementation, associated or not with strength training, upon emotional and cognitive measures in older woman.

Methods

This is a 24-week, parallel-group, double-blind, randomized, placebo-controlled trial. The individuals were randomly allocated into one of the following groups (n=14 each): 1) placebo, 2) creatine supplementation, 3) placebo associated with strength training or 4) creatine supplementation associated with strength training. According to their allocation, the participants were given creatine (4 x 5 g/d for 5 days followed by 5 g/d) or placebo (dextrose at the same dosage) and were strength trained or not. Cognitive function, assessed by a comprehensive battery of tests involving memory, selective attention, and inhibitory control, and emotional measures, assessed by the Geriatric Depression Scale, were evaluated at baseline, after 12 and 24 weeks of the intervention. Muscle strength and food intake were evaluated at baseline and after 24 weeks.

Results

After the 24-week intervention, both training groups (ingesting creatine supplementation and placebo) had significant reductions on the Geriatric Depression Scale scores when compared with the non-trained placebo group (p = 0.001 and p = 0.01, respectively) and the non-trained creatine group (p < 0.001 for both comparison). However, no significant differences were observed between the non-trained placebo and creatine (p = 0.60) groups, or between the trained placebo and creatine groups (p = 0.83). Both trained groups, irrespective of creatine supplementation, had better muscle strength performance than the non-trained groups. Neither strength training nor creatine supplementation altered any parameter of cognitive performance. Food intake remained unchanged.

Conclusion

Creatine supplementation did not promote any significant change in cognitive function and emotional parameters in apparently healthy older individuals. In addition, strength training per se improved emotional state and muscle strength, but not cognition, with no additive effects of creatine supplementation.

Trial Registration

Clinicaltrials.gov NCT01164020     

Dynamic stability and compensatory stepping responses during anterior gait–slip perturbations in people with chronic hemiparetic stroke

To examine the control of dynamic stability and characteristics of the compensatory stepping responses to an unexpected anterior gait slip induced under the non-involved limb in people with hemi-paretic stroke (PwHS) and to examine any resulting adaptive changes in these on the second slip due to experience from prior slip exposure. Ten PwHS experienced overground slip (S1) during walking on the laboratory walkway after 5–8 regular walking (RW) trials followed by a second consecutive slip trial (S2). The slip outcome (backward loss of balance, BLOB and no loss of balance, NLOB) and COM state (i.e. its COM position and velocity) stability were examined between the RW and S1 and S1 and S2 at touchdown (TD) of non-involved limb and at liftoff (LO) of the contralateral limb. At TD there was no difference in stability between RW and S1, however at LO, subjects demonstrated a lower stability on S1 than RW resulting in a 100% backward loss of balance (BLOB) with compensatory stepping response (recovery step, RS, 4/10 or aborted step, AS, 6/10). On S2, although there was no change in stability at TD, there was a significant improvement in stability at LO with a 40% decrease in BLOB. There was also a change in step strategy with a decrease in AS response (60% to 35%, p<0.05) which was replaced by an increase in the ability to step (increased compensatory step length, p<0.05) either via a recovery step or a walkover step. PwHS have the ability to reactively control COM state stability to decrease fall-risk upon a novel slip; prior exposure to a slip did not significantly alter feedforward control but improved the ability to use such feedback control for improved slip outcomes.     

Vibration training: benefits and risks

The main results of our recent several studies, i.e. the measurements of vibration training results for single case and group studies as well as the cardiovascular parameter measurements during vibrations and the corresponding hydrodynamic analysis, are summarized. Our studies and previous work all confirm that vibration training is an effective training method in order to improve maximal strength and flexibility as well as various other factors if the training is properly designed. Some recommendations regarding the proper ranges of frequencies, amplitudes and exposure duration of vibration training are made based on the existing vibration training practice and mechanism analysis, although much work remains to be carried out in order to set up clear rules for various groups of people so that maximal training results could be expected and in the meantime potential dangerous effects could be avoided. Cardiovascular parameter measurements confirm that total peripheral resistance (TPR) to the blood flow is increased during body vibration. Hydrodynamic analysis offers the mechanism for the increase of TPR through the deformation of vessels. As a reaction of compensation, more capillaries are probably opened in order to keep a necessary level of cardiac output needed for the body, resulting in more efficient gas and material metabolism between the blood and muscle fibres. This might be one of the reasons for the various potential beneficial effects of vibration training.     

Tripping without falling; lower limb strength, a limitation for balance recovery and a target for training in the elderly.

To reduce the number of falls in old age, we need to understand the mechanisms underpinning a fall, who are at risk of falling, and what interventions can prevent such individuals from falling. This paper provides an overview of our recent research on tripping and muscle strength in the elderly, addressing these questions. To prevent a fall after tripping over an obstacle, high demands are posed on lower limb muscles. It was shown that the support limb plays an important role in balance recovery by generating the appropriate joint moments during push-off. Older individuals show lower rates of moment generation in all support limb joints and a lower peak ankle moment than young adults. As strength declines with age (due to muscular, tendinous and neural alterations), leg muscle strength might be the limiting factor in preventing a fall. Indeed, high-risk fallers could be identified based on maximum leg press push-off force capacity. Resistance training can reverse the ageing-related loss of strength. Therefore, the effects of 16-weeks resistance training on tripping reactions were studied in a small group of elderly. Maximum push-off force increased significantly by training. Moreover, trainers improved more than controls in moment generation after tripping, especially around the ankle. It can be concluded that transfer of resistance training effects to balance recovery is feasible.     

Alteration in community-dwelling older adults' level walking following perturbation training

While perturbation training is promising in reducing fall-risk among older adults, its impact on altering their spontaneous gait pattern has not been investigated. The purpose of this study was to determine to what extent older adults' gait pattern would be affected by exposure to repeated slips. Seventy-three community-dwelling older adults (age: 72.6±5.4 years) underwent 24 repeated-slip exposure induced by unannounced unlocking and relocking of low-friction sections of a 7-m pathway upon which they walked. Full body kinematics and kinetics were recorded during the training. The gait parameters and the center of mass (COM) stability against backward balance loss were compared before and after the training. The results revealed that the training reduced fall incidence from 43.8% upon the novel slip to 0 at the end of training. After the training, subjects significantly improved gait stability by forward positioning of their COM relative to the base of support without altering gait speed. This forward COM shift resulted from a shortened step at the end of single stance and forward trunk leaning during double stance. They also adopted flat foot landing with knee flexed at touchdown (with an average change of 6.9 and 4.1 degrees, respectively). The perturbation training did alter community-dwelling older adults' spontaneous gait pattern. These changes enabled them to improve their volitional control of stability and their resistance to unpredictable and unpreventable slip-related postural disturbance.     

Suppression of endogenous testosterone production attenuates the response to strength training: a randomized, placebo-controlled, and blinded intervention study

We hypothesized that suppression of endogenous testosterone would inhibit the adaptations to strength training in otherwise healthy men. Twenty-two young men with minor experience with strength training participated in this randomized, placebo-controlled, double-blinded intervention study. The subjects were randomized to treatment with the GnRH analog goserelin (3.6 mg) or placebo (saline) subcutaneously every 4 wk for 12 wk. The strength training period of 8 wk, starting at week 4, included exercises for all major muscles [3-4 sets per exercise x 6-10 repetitions with corresponding 6- to 10-repetition maximum (RM) loads, 3/wk]. A strength test, blood sampling, and whole body DEXA scan were performed at weeks 4 and 12. Endogenous testosterone decreased significantly (P < 0.01) in the goserelin group from 22.6 +/- 5.5 (mean +/- SD) nmol/l to 2.0 +/- 0.5 (week 4) and 1.1 +/- 0.6 nmol/l (week 12), whereas it remained constant in the placebo group. The goserelin group showed no changes in isometric knee extension strength after training, whereas the placebo group increased from 240.2 +/- 41.3 to 264.1 +/- 35.3 Nm (P < 0.05 within and P = 0.05 between groups). Lean mass of the legs increased 0.37 +/- 0.13 and 0.57 +/- 0.30 kg in the goserelin and placebo groups, respectively (P < 0.05 within and P = 0.05 between groups). Body fat mass increased 1.4 +/- 1.0 kg and decreased 0.6 +/- 1.2 kg in the goserelin and placebo groups, respectively (P < 0.05 within and between groups). We conclude that endogenous testosterone is of paramount importance to the adaptation to strength training.     

Effects of walking speed, strength and range of motion on gait stability in healthy older adults

Falls pose a tremendous risk to those over 65 and most falls occur during locomotion. Older adults commonly walk slower, which many believe helps improve walking stability. While increased gait variability predicts future fall risk, increased variability is also caused by walking slower. Thus, we need to better understand how differences in age and walking speed independently affect dynamic stability during walking. We investigated if older adults improved their dynamic stability by walking slower, and how leg strength and flexibility (passive range of motion (ROM)) affected this relationship. Eighteen active healthy older and 17 healthy younger adults walked on a treadmill for 5min each at each of 5 speeds (80-120% of preferred). Local divergence exponents and maximum Floquet multipliers (FM) were calculated to quantify each subject's inherent local dynamic stability. The older subjects walked with the same preferred walking speeds as the younger subjects (p=0.860). However, these older adults still exhibited greater local divergence exponents (p<0.0001) and higher maximum FM (p<0.007) than the younger adults at all walking speeds. These older adults remained more locally unstable (p<0.04) even after adjusting for declines in both strength and ROM. In both age groups, local divergence exponents decreased at slower speeds and increased at faster speeds (p<0.0001). Maximum FM showed similar changes with speed (p<0.02). Both younger and older adults exhibited decreased instability by walking slower, in spite of increased variability. These increases in dynamic instability might be more sensitive indicators of future fall risk than changes in gait variability.     

10周核心力量练习对男性中老年人平衡能力的影响

目的：探讨核心力量练习对中老年男性平衡能力的影响,为运动锻炼改善老年人平衡能力和降低跌倒风险提供依据。方法：选取16名50~60岁男性中老年人,随机分为试验组（核心力量练习）和对照组,每组8人。利用悬吊绳和瑜伽垫进行动、静态支撑与推拉练习以及徒手下肢力量等间歇性组合核心力量训练,共练习10周,每周4~5次,每次50~60 min。对照组保持原有生活习惯。锻炼前后测定受试者静态平衡和动态平衡等指标。结果：①锻炼后试验组闭眼单脚站立时间和动态平衡得分较锻炼前显著升高分别为（9.00±2.27） s、（10.63±1.69） s,P<0.01;（77.38±10.94）、（89.50±5.53）,P<0.01。②锻炼后试验组星形伸展平衡测试（SEBT）,右腿支撑时左腿在8个方向、左腿支撑时右腿在6个方向的SEBT值均较锻炼前显著增加（P<0.01）。结论：10周核心力量练习显著提高男性中老年人的动、静态平衡能力。     

Effects of regular heel-raise training aimed at the soleus muscle on dynamic balance associated with arm movement in elderly women

The effects of low-intensity muscle training with heel-raises on dynamic balance associated with bilateral arm flexion were investigated in postmenopausal elderly women. Twenty-six elderly women were evenly grouped into training and control groups. Training group subjects performed 100 heel raises per day for 2 months. The training was aimed at hypertrophy of the soleus muscle, which has a relatively high proportion (ca. 90%) of slow-twitch muscle fibers and is one of the main postural muscles. Dynamic balance was measured while arm flexion was performed in response to a visual stimulus (simple-reaction condition) or at the subjects' own pace (own-timing condition). The following parameters were compared before and after the training period: plantar flexion strength, thicknesses of the gastrocnemius and soleus (by ultrasound), reaction time of the anterior deltoid in the simple-reaction condition, activation onset timing of postural muscles with respect to the deltoid, movement angles of ankle and hip joints, and postural fluctuation. In the training group only, the following training-related effects were demonstrated: (a) increase in plantar flexor strength and thickness of the soleus, (b) shortening of the deltoid reaction time, (c) earlier activation of the erector spinae in the simple-reaction condition and the soleus in the own-timing condition, and (d) increase in ankle movement in the own-timing condition and a decrease in postural fluctuation. This heel-raise training in the elderly can increase soleus thickness within the triceps surae and improve postural control modality and stability that are effectively contributed to by the leg muscle. This training consists of a low-intensity exercise that requires neither special machines nor a specific environment and can be performed safely for all old-aged groups.     

The acute effects of a caffeine-containing supplement on strength, muscular endurance, and anaerobic capabilities

The purpose of this study was to examine the acute effects of a caffeine-containing supplement on upper- and lower-body strength and muscular endurance as well as anaerobic capabilities. Thirty-seven resistance-trained men (mean +/- SD, age: 21 +/- 2 years) volunteered to participate in this study. On the first laboratory visit, the subjects performed 2 Wingate Anaerobic Tests (WAnTs) to determine peak power (PP) and mean power (MP), as well as tests for 1 repetition maximum (1RM), dynamic constant external resistance strength, and muscular endurance (TOTV; total volume of weight lifted during an endurance test with 80% of the 1RM) on the bilateral leg extension (LE) and free-weight bench press (BP) exercises. Following a minimum of 48 hours of rest, the subjects returned to the laboratory for the second testing session and were randomly assigned to 1 of 2 groups: a supplement group (SUPP; n = 17), which ingested a caffeine-containing supplement, or a placebo group (PLAC; n = 20), which ingested a cellulose placebo. One hour after ingesting either the caffeine-containing supplement or the placebo, the subjects performed 2 WAnTs and were tested for 1RM strength and muscular endurance on the LE and BP exercises. The results indicated that there was a significant (p < 0.05) increase in BP 1RM for the SUPP group, but not for the PLAC group. The caffeine-containing supplement had no effect, however, on LE 1RM, LE TOTV, BP TOTV, PP, and MP. Thus, the caffeine-containing supplement may be an effective supplement for increasing upper-body strength and, therefore, could be useful for competitive and recreational athletes who perform resistance training.