Effects of unilateral electromyostimulation superimposed on voluntary training on strength and cross‐sectional area

In this study we investigate the effects of unilateral voluntary contraction (VC) and electromyostimulation superimposed on VC (EV) training on maximal voluntary (MVC) force and cross‐sectional area (CSA), as assessed by magnetic resonance imaging of knee extensors. Thirty young men were randomly assigned to either a control group (CG), VC group (VG), or EV group (EVG). The VG and EVG trained the right leg isometrically three sessions per week for 6 weeks. After training, MVC increased in the right leg in the VG and in both legs in the EVG, and EVG was significantly different from CG (all P < 0.01). Increased CSA was found only in the right leg in the VG and EVG (P < 0.01), and correlated with improvements of MVC (r = 0.49, P = 0.01). It appeared that the EV training was equally effective as VC at increasing MVC and CSA, while having a greater cross‐education effect. Increased strength without muscle hypertrophy in the unexercised leg of the EVG indicated that neural adaptation was responsible for the cross‐education effect. Muscle Nerve 40: 430–437, 2009     

Vastus lateralis exhibits non‐homogenous adaptation to resistance training

Introduction: Variations in transverse point of measure on the vastus lateralis (VL) may significantly affect the relationship between structure and function. The purpose of this study was to compare changes in muscle architecture at 2 commonly used points of measure (VL0 and VL5). Methods: Maximal strength (1‐repetition maximum [1RM] barbell squat) and muscle architecture were assessed PRE and POST 15 weeks of periodized resistance training. VL0 was 50% of the straight line distance between the greater trochanter and lateral epicondyle of the femur. VL5 was 5cm medial to VL0. Results: Increases in 1RM strength (3.7 ± 2.4 kg; P = 0.004) were observed. Changes in muscle thickness (MT) at VL5 were significantly greater than at VL0 (P = 0.006). Changes in strength correlated with changes in muscle architecture at VL0 only (MT: r = 0.561; fascicle length: r = 0.503). Conclusions: Changes in muscle architecture appear to occur in a non‐homogeneous manner. Muscle Nerve 50 : 785–793, 2014     

Changes in muscle force–length properties affect the early rise of force in vivo

Changes in contractile rate of force development (RFD), measured within a short time interval from contraction initiation, were measured after a period of strength training that led to increases in muscle fascicle length but no measurable change in neuromuscular activity. The relationship between training‐induced shifts in the moment–angle relation and changes in RFD measured to 30 ms (i.e., early) and 200 ms (i.e., late) from the onset of isometric knee extension force were examined; shifts in the moment–angle relation were used as an overall measure of changes in quadriceps muscle fascicle length. A significant proportion of the variance in RFD measured only in the initial contraction phase (0–30 ms) could be explained by shifts in the moment–angle relation (r = ?0.66–0.71; R² = 0.44–0.50). Training‐induced increases in muscle fascicle length may lead to a reduced or complete lack of adaptive gains in contractile RFD, especially in the early contraction phase. Muscle Nerve 39: 512–520, 2009     

Cross‐education after high‐frequency versus low‐frequency volume‐matched handgrip training

Introduction: Cross‐education training programs cause interlimb asymmetry of strength and hypertrophy. We examined the cross‐education effects from a high‐frequency (HF) versus a low‐frequency (LF) volume‐matched handgrip training program on interlimb asymmetry. Methods: Right‐handed participants completed either HF (n = 10; 2 × 6 repetitions 10 times per week) or LF (n = 9; 5 × 8 repetitions 3 times per week) training. Testing occurred twice before and once after 4 weeks of right‐handed isometric handgrip training totaling 120 weekly repetitions. Measures were maximal isometric handgrip and wrist flexion torque, muscle thickness, and muscle activation (electromyography; EMG). Results: Grip strength was greater in both limbs posttraining, pooled across groups (P < 0.001). Trained limb muscle thickness increased in both groups (P < 0.05; untrained, P = 0.897). EMG and wrist flexion torque did not change (all P > 0.103). Discussion: Both LF and HF induced cross‐education of grip strength to the untrained limb, but HF did not reduce asymmetry. These findings have implications for injury rehabilitation. Muscle Nerve 56 : 689–695, 2017     

High-intensity resistance training amplifies muscle hypertrophy and functional gains in persons with Parkinson's disease.

Strength deficits in persons with Parkinson's disease (PD) have been identified as a contributor to bradykinesia. However, there is little research that examines the effect of resistance training on muscle size, muscle force production, and mobility in persons with PD. The purpose of this exploratory study was to examine, in persons with PD, the changes in quadriceps muscle volume, muscle force production, and mobility as a result of a 12-week high-force eccentric resistance training program and to compare the effects to a standard-care control. Nineteen individuals with idiopathic PD were recruited and consented to participate. Matched assignment for age and disease severity resulted in 10 participants in the eccentric group and 9 participants in the control group. All participants were tested prior to and following a 12-week intervention period with testing and training conducted at standardized times in their medication cycle. The eccentric group performed high-force quadriceps contractions on an eccentric ergometer 3 days a week for 12 weeks. The standard-care group exercise program encompassed standard exercise management of PD. The outcome variables were quadriceps muscle volume, muscle force, and mobility measures (6-minute walk, stair ascent/descent time). Each outcome variable was tested using separate one-way analyses of covariance on the difference scores. Muscle volume, muscle force, and functional status improvements occurred in persons with PD as a result of high-force eccentric resistance training. The eccentric group demonstrated significantly greater difference scores for muscle structure, stair descent, and 6-minute walk (P < 0.05). Magnitude of effect size estimators for the eccentric group consistently exceeded those in the standard-care group for all variables. To our knowledge, this is the first clinical trial to investigate and demonstrate the effects of eccentric resistance training on muscle hypertrophy, strength, and mobility in persons with PD. Additional research is needed to determine the anatomical and neurological mechanisms of the observed strength gains and mobility improvements.     

Muscular adaptations and insulin‐like growth factor‐1 responses to resistance training are stretch‐mediated

Introduction: Modulation of muscle characteristics was attempted through altering muscle stretch during resistance training. We hypothesized that stretch would enhance muscle responses. Methods: Participants trained for 8 weeks, loading the quadriceps in a shortened (SL, 0–50° knee flexion; n = 10) or lengthened (LL, 40–90°; n = 11) position, followed by 4 weeks of detraining. Controls (CON; n = 10) were untrained. Quadriceps strength, vastus lateralis architecture, anatomical cross‐sectional area (aCSA), and serum insulin‐like growth factor‐1 (IGF‐1) were measured at weeks 0, 8, 10, and 12. Results: Increases in fascicle length (29 ± 4% vs. 14 ± 4%), distal aCSA (53 ± 12% vs. 18 ± 8%), strength (26 ± 6% vs. 7 ± 3%), and IGF‐1 (31 ± 6% vs. 7 ± 6%) were greater in LL compared with SL muscles (P < 0.05). No changes occurred in CON. Detraining decrements in strength and aCSA were greater in SL than LL muscles (P < 0.05). Conclusions: Enhanced muscle in vivo (and somewhat IGF‐1) adaptations to resistance training are concurrent with muscle stretch, which warrants its inclusion within training. Muscle Nerve 49 : 108–119, 2014     

A community-based strength training programme increases muscle strength and physical activity in young people with Down syndrome: A randomised controlled trial

This randomised controlled trial investigated the effects of a student-led progressive resistance training (PRT) programme in adolescents and young adults with Down syndrome. Sixty-eight young people with Down syndrome (30 female, 38 male; mean age 17.9 ± 2.6 years) and mild to moderate intellectual disability were randomly allocated to a PRT programme (n = 34) or a social group (n = 34). Participants in the PRT group trained twice a week for 10 weeks at a community gymnasium with a physiotherapy student mentor using pin-loaded weight machines. Participants in the social group completed a 10-week programme of social activities also with a student mentor once a week for 90 min. Work performance, muscle strength and physical activity levels were assessed at weeks 0, 11 and 24 by an assessor blind to group allocation. Data were analysed using ANCOVA with baseline measures as covariate. Participants attended 92% of their scheduled sessions. There was no difference between the groups on work task performance. The PRT group increased their upper and lower limb strength at week 11 compared to the control group, but only their lower limb muscle strength at week 24. There was a significant difference in physical activity levels in favour of the PRT group at week 24 but not at week 11. PRT using a student mentor model helps young people with Down syndrome become stronger and more physically active but its effect on work task performance is unclear.     

Blood flow restriction increases metabolic stress but decreases muscle activation during high‐load resistance exercise

Introduction: We investigated differences in metabolic stress (lactate) and muscle activation (electromyography; EMG) when high‐load resistance exercise (HL) is compared with a condition in which blood flow restriction (BFR) is applied during the exercise or during the rest interval. Methods: Twelve participants performed HL with BFR during the intervals (BFR‐I), during the set (BFR‐S), and without BFR. Each condition consisted of 3 sets of 8 repetitions with knee extension at 70% of 1‐repetition maximum. Lactate and root mean square (RMS) from the surface EMG of the vastus lateralis were calculated. Results: Lactate increased in all protocols but was higher with BFR‐I than with BFR‐S and HL. RMS decreased under all conditions, with a larger effect size in BFR‐I (1.47) than in BFR‐S (0.66) and HL (0.59). Discussion: BFR‐I increases lactate, possibly as a result of reduced restoration of ATP. Muscle activation seems to be impacted by mechanical stress but may be reduced by metabolic stress. Muscle Nerve 57 : 107–111, 2018     

Structural integrity of the corpus callosum predicts long‐term transfer of fluid intelligence‐related training gains in normal aging

Although cognitive training usually improves cognitive test performance, the capability to transfer these training gains into respective or functionally related cognitive domains varies significantly. Since most studies demonstrate rather limited transfer effects in older adults, aging might be an important factor in transfer capability differences. This study investigated the transfer capability of logical reasoning training gains to a measure of Fluid Intelligence (Gf) in relation to age, general intelligence, and brain structural integrity as measured by diffusion tensor imaging. In a group of 41 highly educated healthy elderly, 71% demonstrated successful transfer immediately after a 4‐week training session (i.e. short‐term transfer). In a subgroup of 22% of subjects transfer maintained over a 3‐month follow‐up period (i.e. long‐term transfer). While short‐term transfer was not related to structural integrity, long‐term transfer was associated with increased structural integrity in corpus and genu of the corpus callosum. Since callosal structural integrity was also related to age (in the present and foregoing studies), previously observed associations between age and transfer might be moderated by the structural integrity. Surprisingly, age was not directly associated with transfer in this study which could be explained by the multi‐dependency of the structural integrity (modulating factors beside age, e.g. genetics). In this highly educated sample, general intelligence was not related to transfer suggesting that high intelligence is not sufficient for transfer in normal aging. Further studies are needed to reveal the interaction of transfer, age, and structural integrity and delineate mechanisms of age‐dependent transfer capabilities. Hum Brain Mapp 35:309–318, 2014. © 2012 Wiley Periodicals, Inc.     

Adaptations in maximal motor unit discharge rate to strength training in young and older adults

Six young (mean = 23 years) and 6 older (mean = 76 years) adults participated in isometric resistance training 5 days/week for 6 weeks. The task involved isometric fifth finger abduction. Maximal motor unit discharge rates (MUDRs) were obtained from the abductor digiti minimi of each hand at 0, 2, 14, and 42 days of training using a quadrifilar needle electrode and automatic spike recognition software. In agreement with previous findings, maximal MUDR at baseline was significantly lower in older adults (P < 0.001), averaging 51.5 (+/-17.13) HZ in young and 43.3 (+/-14.88) HZ in older adults. In response to resistance training, maximal voluntary force increased 25% in young and 33% in older subjects (P < 0.001). Maximal MUDR increased significantly (11% young, 23% older) on day 2 [F(3,36) = 2.58, P < 0.05], but in older subjects returned to baseline levels thereafter. These adaptations in abductor digiti minimi MUDR suggest a two-part response to strengthening fifth finger abduction: early disinhibition followed by altered MU activation.Copyright 2001 John Wiley & Sons, Inc.     

The effect of a combined strength and proprioceptive training on muscle strength and postural balance in boys with intellectual disability: An exploratory study

The aim of our study was to investigate the effect of a combined strength and proprioception training (CSPT) program on muscle strength and postural balance in children with intellectual disability (ID). The maximum voluntary contraction (MVC) and postural parameters (CoP_Vm, CoP_LX, CoP_LY) of 20 children with ID were recorded before and after 8 weeks of a CSPT program. The participants were divided into two groups: an experimental group who attended a CSPT program and a control group who continued with daily activities. In the trained group, the MVC increased significantly (p < 0.001) after the training period and the postural parameters decreased significantly in Double-Leg Stance (DLS) and One-Leg Stance (OLS) during the firm surface condition as well as in the DLS during the foam surface condition; in both eyes open (EO) and eyes closed (EC) conditions. A CSPT program improves postural balance in children with ID could be due to the enhancement in muscle strength and proprioceptive input integration.     

A two‐year randomized controlled trial of progressive resistance exercise for Parkinson's disease

The effects of progressive resistance exercise (PRE) on the motor signs of Parkinson's disease have not been studied in controlled trials. The objective of the current trial was to compare 6‐, 12‐, 18‐, and 24‐month outcomes of patients with Parkinson's disease who received PRE with a stretching, balance, and strengthening exercise program. The authors conducted a randomized controlled trial between September 2007 and July 2011. Pairs of patients matched by sex and off‐medication scores on the Unified Parkinson's Disease Rating Scale, motor subscale (UPDRS‐III), were randomly assigned to the interventions with a 1:1 allocation ratio. The PRE group performed a weight‐lifting program. The modified fitness counts (mFC) group performed a stretching, balance, and strengthening exercise program. Patients exercised 2 days per week for 24 months at a gym. A personal trainer directed both weekly sessions for the first 6 months and 1 weekly session after 6 months. The primary outcome was the off‐medication UPDRS‐III score. Patients were followed for 24 months at 6‐month intervals. Of 51 patients, 20 in the PRE group and 18 in the mFC group completed the trial. At 24 months, the mean off‐medication UPDRS‐III score decreased more with PRE than with mFC (mean difference, ?7.3 points; 95% confidence interval, ?11.3 to ?3.6; P<0.001). The PRE group had 10 adverse events, and the mFC group had 7 adverse events. PRE demonstrated a statistically and clinically significant reduction in UPDRS‐III scores compared with mFC and is recommended as a useful adjunct therapy to improve Parkinsonian motor signs. © 2013 Movement Disorder Society     

力量训练和功能训练偏瘫阴性患者上肢神经肌肉功能的恢复：个案特点*

背景：偏瘫患者上肢功能康复目前许多治疗方法,但针对患者的病症,以独立功能能力为目标的任务导向性训练方法报道不多。 目的：探讨功能训练和力量训练对偏瘫阴性特征患者上肢动作能力恢复的疗效。 方法：对因脑蛛网膜下腔出血,做动脉瘤栓塞时血管壁沉淀物堵塞中动脉血管造成右偏瘫致上运动神经元损伤的偏瘫阴性患者进行训练前后的BrunstormⅤ级动作测试,同时进行录像和肌电图测试,通过录像发现运动障碍,找出中枢性瘫痪肌肉,对患者瘫痪肌的功能进行运动学分析,治疗前后患侧神经肌肉功能的进步情况。 结果与结论：通过150次的训练,使患者完全失用的右手能完成功能训练(吃香蕉动作)14次。说明功能训练和力量训练对偏瘫阴性特征患者上肢动作能力的康复效果显著。