Effects of different strength training frequencies during reduced training period on strength and muscle cross-sectional area

This study investigated the effects of different reduced strength training (RST) frequencies on half-squat 1 RM and quadriceps cross-sectional area (QCSA). Thirty-three untrained males (24.7?±?3.9 years; 1.73?±?0.08?m; 74.6?±?8.4?kg) underwent a 16-week experimental period (i.e. eight weeks of strength training [ST] followed by additional eight weeks of RST). During the ST period, the participants performed 3–4 sets of 6–12 RM, three sessions/week in half-squat and knee extension exercises. Following ST, the participants were randomly allocated to one of three groups: reduced strength training with one (RST1) or two sessions per week (RST2), and ceased training (CT). Both RST1 and RST2 groups had their training frequency and total training volume-load (i.e. RST1?=?50.3% and RST2?=?57.1%) reduced, while the CT group stopped training completely. Half-squat 1 RM (RST1?=?27.9%; RST2?=?26.7%; and CT?=?28.4%) and QCSA (RST1?=?6.1%; RST2?=?6.9%; and CT?=?5.8%) increased significantly (p?<?.05) in all groups after eight weeks of ST. No significant changes were observed in 1 RM and QCSA for RST1 and RST2 groups after the RST period, while the CT group demonstrated a decrease in half-squat 1 RM (22.6%) and QCSA (5.4%) when compared to the ST period (p?<?.05). In conclusion, different RST frequencies applied were able to maintain muscle mass and strength performance obtained over the regular ST period. Thus, it appears that RST frequency does not affect the maintenance of muscle mass and strength in untrained males, as long as volume-load is equated between frequencies.     

Effects of high-intensity resistance circuit-based training in hypoxia on body composition and strength performance

Abstract

Hypoxic training methods are increasingly being used by researchers in an attempt to improve performance in normoxic ambients. Moreover, previous research suggests that resistance training in hypoxia can cause physiological and muscle adaptations. The primary aim of this study was to compare the effects of 8 weeks of high-intensity resistance circuit-based (HRC) training in hypoxia on body composition and strength performance. The secondary aim was to examine the effects of HRC on metabolic parameters. Twenty-eight male participants were randomly assigned to either hypoxia (Fraction of inspired oxygen [F_IO₂]?=?15%; HRC_hyp: n?=?15; age: 24.6?±?6.8 years; height: 177.4?±?5.9?cm; weight: 74.9?±?11.5?kg) or normoxia [F_IO₂]?=?20.9%; HRC_norm: n?=?13; age: 23.2?±?5.2 years; height: 173.4?±?6.2?cm; weight: 69.4?±?7.4?kg) groups. Training sessions consisted of two blocks of three exercises (Block 1: bench press, leg extension and front pull down; Block 2: deadlift, elbow flexion and ankle extension). Each exercise was performed at six repetition maximum. Rest periods lasted for 35-s between exercises, 3-min between sets and 5-min between blocks. Participants exercised twice weekly for 8 weeks, and body composition, strength and blood tests were performed before and after the training program. Lean body mass and bone mineral density significantly increased over time in the HRC_hyp (p?<?.005; ES?=?0.14 and p?<?.014; ES?=?0.19, respectively) but not in the HRC_norm after training. Both groups improved their strength performance over time (p?<?.001), but without group effect differences. These results indicate that simulated hypoxia during HRC exercise produced trivial effects on lean body mass and bone mineral density compared to normoxia.     

Effects of isometric quadriceps strength training at different muscle lengths on dynamic torque production

This study aims to (1) determine whether isometric training at a short vs. long quadriceps muscle length affects concentric torque production; (2) examine the relationship between muscle hypertrophy and concentric torque; and (3) determine whether changes in fascicle length are associated with changes in concentric torque.

Sixteen men performed isometric training at a short (SL, n = 8) or a long muscle length (LL, n = 8). Changes in maximal concentric torque were measured at 30, 60, 90, 120, 180, 240 and 300 rad · s^?1. The relationships between the changes in concentric torque, cross-sectional area, volume and fascicle length were tested.

Concentric torque increased significantly after training only in LL and at angular velocities of 30 and 120 rad · s^?1 by 12–13% (P < 0.05). Muscle size increased in LL only, the changes were correlated (r = 0.73–0.93, P < 0.05) with the changes in concentric torque. Vastus lateralis (VL) fascicle length increased in both groups (5.4 ± 4.9%, P = 0.001) but the change was not correlated with changes in concentric torque in either group.

Isometric training-induced increases in muscle size and concentric torque were best elicited by training at long muscle lengths. These results highlight a clear muscle length dependence of isometric training on dynamic torque production.     

Effects of adding a weekly eccentric-overload training session on strength and athletic performance in team-handball players

To investigate the influence of adding a weekly eccentric-overload training (EOT) session in several athletic performance’s tests, 18 team-handball players were assigned either to an EOT (n?=?11) or a Control (n?=?7) group. Both groups continued to perform the same habitual strength training, but the EOT group added one session/week during a 7-week training programme consisting of four sets of eight repetitions for the bilateral half-squat and unilateral lunge exercises. The test battery included handball throwing velocity, maximum dynamic strength (1RM), countermovement jump (CMJ), 20?m sprint, triple hop for distance, and eccentric/concentric power in both the half-squat and lunge exercises. Data were analysed using magnitude-based inferences. Both groups improved their 1RM in the half squat, 20?m sprint time, and CMJ performance to a similar extent, but the EOT group showed a beneficial effect for both right [(42/58/0), possibly positive] and left [(99/1/0), very likely positive] triple hop for distance performance. In addition, the EOT group showed greater power output improvements in both eccentric and concentric phases of the half-squat (difference in percent of change ranging from 6.5% to 22.0%) and lunge exercises (difference in per cent of change ranging from 13.1% to 24.9%). Nevertheless, no group showed changes in handball throwing velocity. Selected variables related to team-handball performance (i.e. functional jumping performance, power output) can be improved by adding a single EOT session per week, highlighting the usefulness of this low-volume/high-intensity training when aiming at optimizing dynamic athletic performance.     

Sit-to-stand performance of older adults following strength training

A group of healthy older adults completed an 8-week resistance-training program. For 38 participants (14 men, 24 women; ages 60-90 years; M mass = 73.2 kg, SD = 12.3; M height = 1.65 m, SD = 0.08), pre- and postprogram sit-to-stand performance was analyzed (60 Hz video) focusing on center of mass kinematics surrounding transition. Significant changes were attributed to improved strength. Peak forward, downward, and upward velocities increased (16, 59, and 26%, respectively), and relative transition time was delayed 27%. These behaviors were more similar to those of healthy younger adults. Results also indicated strategy changes. Participants exploited their improved strength, forming a distinctive movement pattern emphasizing stability followed by a brisk rise. These adaptations represent meaningfully improved function in an important daily living activity.     

Neural mechanisms of strength increase after one-week motor imagery training

The neural mechanisms explaining strength increase following mental training by motor imagery (MI) are not clearly understood. While gains are mostly attributed to cortical reorganization, the sub-cortical adaptations have never been investigated. The present study investigated the effects of MI training on muscle force capacity and the related spinal and supraspinal mechanisms. Eighteen young healthy participants (mean age: 22.5?±?2.6) took part in the experiment. They were distributed into two groups: a control group (n?=?9) and an MI training group (n?=?9). The MI group performed seven consecutive sessions (one per day) of imagined maximal isometric plantar flexion (4 blocks of 25 trials per session). The control group did not engage in any physical or mental training. Both groups were tested for the isometric maximal plantar flexion torque (MVC) and the rate of torque development (RTD) before and after the training session. In addition, soleus and medial gastrocnemius spinal and supraspinal adaptations were assessed through the recording of H-reflexes and V-waves, with electrical stimulations of the posterior tibial nerve evoked at rest and during MVC, respectively. After one week, only the MI training group increased both plantar flexion MVC and RTD. The enhancement of muscle torque capacity was accompanied by significant increase of electromyographic activity and V-wave during MVC and of H-reflex at rest. The increased cortical descending neural drive and the excitability of spinal networks at rest could explain the greater RTD and MVC after one week of MI training.     

基于两种安排模式下的三级跳远运动员小肌群力量训练效果研究

小肌群训练作为三级跳远运动员最重要的体能训练手段之一,对运动员专项竞技能力的提高具有重要意义。传统三级跳远运动员小肌群训练在安排上具有相对集中的特点。随着对三级跳远运动员专项竞技需要认识的加深,其小肌群训练计划安排的密度、与其它训练因素的组合方式等方面都发生了明显的变化。目前我国高水平三级跳远教练员已经将全新的分散安排模式应用于小肌群训练实践,并取得了较好的训练效果。为分散安排模式小肌群训练的成功应用找到相关理论依据是当前三级跳远理论研究领域中亟待解决的问题。     

Effects of different intensities of resistance training with equated volume load on muscle strength and hypertrophy

The present study investigated the effects of different intensities of resistance training (RT) on elbow flexion and leg press one-repetition maximum (1RM) and muscle cross-sectional area (CSA). Thirty men volunteered to participate in an RT programme, performed twice a week for 12 weeks. The study employed a within-subject design, in which one leg and arm trained at 20% 1RM (G20) and the contralateral limb was randomly assigned to one of the three conditions: 40% (G40); 60% (G60), and 80% 1RM (G80). The G20 started RT session with three sets to failure. After G20 training, the number of sets was adjusted for the other contralateral limb conditions with volume-matched. CSA and 1RM were assessed at pre, post-6 weeks, and post-12 weeks. There was time effect for CSA for the vastus lateralis (VL) (8.9%, 20.5%, 20.4%, and 19.5%) and elbow flexors (EF) (11.4%, 25.3%, 25.1%, and 25%) in G20, G40, G60, and G80, respectively (p?>?.05). G80 showed higher CSA than G20 for VL (19.5% vs. 8.9%) and EF (25% vs. 11.4%) at post-12 weeks (p?p?相似文献   

Effects of different instructional constraints on task performance and emergence of coordination in children

Abstract

The objectives of this study were to determine the impact of different instructional constraints on standing board jump (sbj) performance in children and understand the underlying changes in emergent movement patterns. Two groups of novice participants were provided with either externally or internally focused attentional instructions during an intervention phase. Pre- and post-test sessions were undertaken to determine changes to performance and movement patterns. Thirty-six primary fourth-grade male students were recruited for this study and randomly assigned to either an external, internal focus or control group. Different instructional constraints with either an external focus (image of the achievement) or an internal focus (image of the act) were provided to the participants. Performance scores (jump distances), and data from key kinematic (joint range of motion, ROM) and kinetic variables (jump impulses) were collected. Instructional constraints with an emphasis on an external focus of attention were generally more effective in assisting learners to improve jump distances. Intra-individual analyses highlighted how enhanced jump distances for successful participants may be concomitant with specific changes to kinematic and kinetic variables. Larger joint ROM and adjustment to a comparatively larger horizontal impulse to a vertical impulse were observed for more successful participants at post-test performance. From a constraints-led perspective, the inclusion of instructional constraints encouraging self-adjustments in the control of movements (i.e., image of achievement) had a beneficial effect on individuals performing the standing broad jump task. However, the advantage of using an external focus of attentional instructions could be task- and individual-specific.     

Effects of multicycle-run training on triathlete performance

The purpose of this study was to determine the effect of triathlon training using multiple, short cycle-run sequences (multicycle-run training) on cycle-run performance. Twelve competitive triathletes, randomized into two groups, underwent multicycle-run training or normal training for 6 weeks. During this period, baseline training remained the same for both groups, and only the high-intensity component differed. The differentiated exercises were performed at or above 100% maximal aerobic velocity. The improvements in overall cycle-run performance were similar (3.3 +/- 1.4 % and 6.1 +/- 1.7% rise in Performance in multicycle-run and normal training, respectively). However, the improvement in performance was significantly greater for the multicycle-run training (-11.2 +/- 6.8 s versus -1.2 +/- 7. 7 s for multicycle-run training and normal training, respectively) during both the cycle-run change and the first 333-m lap, which together are termed the cycle-run transition. We concluded that 6 weeks of multicycle-run training did not induce greater improvement in cycle-run performance than did normal training in competitive triathletes. However, it did induce significant improvement in the cycle-run transition. This finding indicates that multicycle-run training may help competitive triathletes to develop greater skill and better physiological adaptations during this critical transition period of the triathlon race.     

Effects of high-intensity interval training on canoeing performance

The purpose of this study was to compare the effects of high-intensity interval training (HIIT) and moderate-intensity continuous training (MICT) utilizing a canoeing ergometer on endurance determinants, as well as aerobic and anaerobic performances among flat-water canoeists. Fourteen well-trained male flat-water canoeists were divided into an HIIT group or an MICT group. All subjects performed a continuous graded exercise test (GXT) and three fixed-distance (200, 500, and 1000?m) performance tests on a canoeing ergometer to determine canoeing economy, peak oxygen uptake (VO₂peak), and power at VO₂peak, and to calculate the critical velocity (CV) and anaerobic work capacity before and after the training programmes. The training programme involved training on a canoeing ergometer three times per week for four weeks. HIIT consisted of seven 2 min canoeing bouts at an intensity of 90% VO₂peak separated by 1 min of rest. The MICT group was trained at an intensity of 65% VO₂peak continuously for 20 min. After four weeks of training, performance in the 200-m distance test and the power at VO₂peak significantly improved in the HIIT group; performance in the 500?m and 1000?m distances and CV significantly improved in the MICT group. However, all variables were not significantly different between groups. It is concluded that HIIT for four weeks is an effective training strategy for improvement of short-distance canoeing performance. In contrast, MICT improves middle-distance canoeing performances and aerobic capacity.     

核心力量训练对我国优秀跳水运动员不同力量形式的实效性研究

通过设计和运用多种形式的核心力量训练手段,对我国20名优秀跳水运动员进行为期8周的核心力量训练,验证其对提高跳水运动员不同形式力量能力的影响效果.结果显示,跳水运动员的弹跳力(原地摸高指标)和平衡稳定性(俯桥指标)都有非常显著的提高(P＜0.05),相对最大力量方面也有明显的进步.其中,跳深跨越和夹球收腿跳等指标并未表现出显著性,但这仅是统计学上的解释,根据这些指标的测试要求,它们带有明显的综合身体素质特征,因而推测训练的即刻效应并不明显.同时,研究进一步指出了核心力量训练的作用原理及跳水运动员核心力量训练的选择取向,预示着核心力量训练应成为该项目运动员体能训练的一个重要组成部分.     

Effects of dynamic resistance training on fascicle length and isometric strength

The aims of this study were to assess changes in muscle architecture, isometric and dynamic strength of the leg extensor muscles, resulting from dynamic resistance training, and the relationships between strength and muscle architecture variables. The participants (n = 30) were randomly assigned to one of two groups. The training group (n = 16; age 21.8 +/- 2.3 years, body mass 74.8 +/- 9.2 kg, height 1.75 +/- 0.08 m) performed dynamic resistance training for 13 weeks. The control group (n = 14; age 19.9 +/- 1.5 years, body mass 74.0 +/- 8.5 kg, height 1.76 +/- 0.05 m) did not perform any resistance training. Maximal dynamic and isometric strength were tested in both groups, before and after the training period. The members of the training group used the free-weight squat lift (90 degrees ) as their training exercise. The concentric phase of the squat was performed explosively. Skeletal muscle architecture of the vastus lateralis was visualized using ultrasonography. At the end of the study, significant increases in vastus lateralis muscle thickness (+6.9%, P < 0.001), fascicle length (+10.3%, P < 0.05), one-repetition maximum (+8.2%, P < 0.05), rate of force development (+23.8%, P < 0.05) and average force produced in the first 500 ms (+11.7%, P < 0.05) were seen only in the training group. Adaptations to the muscle architecture in the training group limited the loss of fibre force, and improved the capacity for developing higher velocities of contraction. The architectural changes in the training group were similar to those seen in studies where high-speed training was performed. In conclusion, dynamic resistance training with light loads leads to increases in muscle thickness and fascicle length, which might be related to a more efficient transmission of fibre force to the tendon.     

Effects of added elastic tubes on open-chain knee extensor strength training

Attaching elastic tubes (ETs) to resistance training machines can affect the exercise load profile. The purpose of this study was to assess the training effects of added ETs, which were strategically attached to provide additional loads only during the deceleration phase of the knee extension exercise. Twenty-two healthy participants, assigned to either an experimental group (with ETs) or a control group (without ETs), participated in a 12-week strength-training program using a knee extension exercise machine. The acceleration effects were quantified and a method of attaching the ETs to the knee extension machine was developed. The effects of the added ETs were analysed by testing dynamic and isometric maximum contractions at four knee flexion angles (10°, 30°, 50°, and 80°). Analyses of covariance with the initial values as the covariate were used to examine the ET effects. A greater increase in isometric maximum strength was found in the experimental group than in the control group at knee flexion angles of 10° [effect size (ES) = 2.25] and 30° (ES = 1.18). No significant difference in the dynamic maximum strength was found between the groups. The use of ETs increased strength at smaller knee flexion angles with quadriceps that were relatively short.     

不同运动方式对2型糖尿病患者血糖相关指标的影响

目的:比较12周有氧运动和抗阻训练对2型糖尿病患者血糖相关指标影响的差异,为制定特异性的运动处方提供依据.方法:将符合标准的受试者随机分为有氧运动组(14人)、抗阻训练组(13人)、对照组(15人),有氧运动组和抗阻训练组进行每周3次、共12周的运动干预,对照组保持日常生活习惯不变.实验前后分别测定血糖(包括空腹血糖和运动后非空腹血糖)、糖化血红蛋白(HbA1c)、心率和血压等指标.结果:12周运动干预后,有氧运动组和抗阻训练组空腹血糖、运动后非空腹血糖、HbA1c均下降(P<0.05),但抗阻训练组运动后非空腹血糖、HbA1c降低的程度(分别为38%和21%)要大于有氧运动组(分别为26%和9%)(P<0.01),两组安静心率和血压无显著变化(P>0.05).对照组所有指标的变化不明显.结论:有氧运动和抗阻训练均能有效降低2型糖尿病患者的血糖和HbA1c水平,但抗阻训练对运动后非空腹血糖和HbA1c水平的改善要优于有氧运动.     

Effects of inspiratory muscle training on time-trial performance in trained cyclists

We evaluated the effects of specific inspiratory muscle training on simulated time-trial performance in trained cyclists. Using a double-blind, placebo-controlled design, 16 male cyclists (VO2max = 64 +/- 2 ml x kg(-1) x min(-1); mean +/- s(x)) were assigned at random to either an experimental (pressure-threshold inspiratory muscle training) or sham-training control (placebo) group. Pulmonary function, maximum dynamic inspiratory muscle function and the physiological and perceptual responses to maximal incremental cycling were assessed. Simulated time-trial performance (20 and 40 km) was quantified as the time to complete pre-set amounts of work. Pulmonary function was unchanged after the intervention, but dynamic inspiratory muscle function improved in the inspiratory muscle training group (P < or = 0.05). After the intervention, the inspiratory muscle training group experienced a reduction in the perception of respiratory and peripheral effort (Borg CR10: 16 +/- 4% and 18 +/- 4% respectively; compared with placebo, P < or = 0.01) and completed the simulated 20 and 40 km time-trials faster than the placebo group [66 +/- 30 and 115 +/- 38 s (3.8 +/- 1.7% and 4.6 +/- 1.9%) faster respectively; P = 0.025 and 0.009]. These results support evidence that specific inspiratory muscle training attenuates the perceptual response to maximal incremental exercise. Furthermore, they provide evidence of performance enhancements in competitive cyclists after inspiratory muscle training.     

Effects of dietary antioxidants on training and performance in female runners

Abstract

Exercise-induced oxidative stress is implicated in muscle damage and fatigue which has led athletes to embark on antioxidant supplementation regimes to negate these effects. This study investigated the intake of vitamin C (VC) (1 g), blackcurrant (BC) juice (15 mg VC, 300 mg anthocyanins) and placebo in isocaloric drink form on training progression, incremental running test and 5-km time-trial performance. Twenty-three trained female runners (age, 31±8 y; mean±SD) completed three blocks of high-intensity training for 3 wks and 3 days, separated by a washout (~3.7 wks). Changes in training and performance with each treatment were analysed with a mixed linear model, adjusting for performance at the beginning of each training block. Markers of oxidative status included protein carbonyl, malondialdehyde (in plasma and in vitro erythrocytes), ascorbic acid, uric acid and erythrocyte enzyme activity of superoxide dismutase, catalase and glutathione peroxidase were analysed. There was a likely harmful effect on mean running speed during training when taking VC (1.3%; 90% confidence limits ±1.3%). Effects of the two treatments relative to placebo on mean performance in the incremental test and time trial were unclear, but runners faster by 1 SD of peak speed demonstrated a possible improvement on peak running speed with BC juice (1.9%; ±2.5%). Following VC, certain oxidative markers were elevated: catalase at rest (23%; ±21%), protein carbonyls at rest (27%; ±38%) and superoxide dismutase post-exercise (8.3%; ±9.3%). In conclusion, athletes should be cautioned about taking VC chronically, however, BC may improve performance in the elite.     

Effects of inspiratory muscle training on time-trial performance in trained cyclists

We evaluated the effects of specific inspiratory muscle training on simulated time-trial performance in trained cyclists. Using a double-blind, placebo-controlled design, 16 male cyclists (VO 2max = 64 - 2 ml·kg -1 ·min -1 ; mean - sx ¥ ) were assigned at random to either an experimental (pressure-threshold inspiratory muscle training) or sham-training control (placebo) group. Pulmonary function, maximum dynamic inspiratory muscle function and the physiological and perceptual responses to maximal incremental cycling were assessed. Simulated time-trial performance (20 and 40 km) was quantified as the time to complete pre-set amounts of work. Pulmonary function was unchanged after the intervention, but dynamic inspiratory muscle function improved in the inspiratory muscle training group ( P h 0.05). After the intervention, the inspiratory muscle training group experienced a reduction in the perception of respiratory and peripheral effort (Borg CR10: 16 - 4% and 18 - 4% respectively; compared with placebo, P h 0.01) and completed the simulated 20 and 40 km time-trials faster than the placebo group [66 - 30 and 115 - 38 s (3.8 - 1.7% and 4.6 - 1.9%) faster respectively; P = 0.025 and 0.009]. These results support evidence that specific inspiratory muscle training attenuates the perceptual response to maximal incremental exercise. Furthermore, they provide evidence of performance enhancements in competitive cyclists after inspiratory muscle training.     

Technical performance effectiveness subsequent to complex motor skills training in young boxers

Abstract

Boxing is a sport that comprises a wide variety of integrated offensive, defensive and counter-attack skills performed in an unpredictable environment. Mastering the variety of complex motor skills (CMS) that are required in a boxing match allows the player to employ the best motor performance in most positions of the actual game. This study aimed to assess the associations between implementing CMS versus simple motor skill (SMS) training and the subsequent changes in physical, technical and technical performance effectiveness (TPE) variables in junior boxers. We employed an experimental design that comprised two groups (each 20 males, mean age = 15.22±0.62 years). For 12 weeks, intervention boxers received CMS training, while controls received traditional SMS training. Physical, technical and TPE variables were measured before and after the training programs. Although the two groups were of similar abilities at baseline, there were statistically significant differences (P<0.05) between the intervention and control boxers in the post measures, to the advantage of the intervention group. In terms of absolute (i.e. differences in) or relative (i.e. ratios of) improvements, the intervention group exhibited more favourable values across the variables, and better performance. Developing CMS of junior boxers could contribute positively to their physical and technical abilities, and enhance their TPE.