首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献，搜索用时 844 毫秒
1.
Ten healthy males and ten healthy females aged 21.5 +/- 3.2 years (mean +/- s) participated in the study, which was designed to evaluate the effectiveness of sensory level-high volt pulsed electrical current (HVPC) on delayed-onset muscle soreness (DOMS). Arm discomfort, elbow extension range of motion and isometric elbow flexion strength were obtained as baseline measurements. Delayed-onset muscle soreness was induced in the participants' dominant or non-dominant arm using two sets of 20 maximal eccentric elbow flexion contractions. After the induction of DOMS, the participants were randomly divided into an experimental condition (HVPC) or a placebo condition. The experimental condition consisted of 20 min of HVPC immediately after the induction of DOMS, and 20 min every 24 h for three consecutive days thereafter. The participants in the placebo condition received an intervention similar in design; however, no electrical current was administered. Baseline measurements were reevaluated at 24, 48, 72 and 96 h after the induction of DOMS. Three weeks later, the participants returned and the protocol was repeated on the contralateral limb, using the opposite intervention (HVPC or placebo). Repeated-measures analysis of variance revealed a significant increase in overall arm discomfort, decrease in elbow extension and decrease in isometric strength for both conditions over time. No significant main effect of treatment, or time-by-treatment interaction, was found for the HVPC condition when compared with the placebo condition for any variable. Sensory-level HVPC, as utilized in our application, was ineffective in reducing the measured variables associated with DOMS.  相似文献   

2.
Abstract

This study was undertaken to examine the acute effect of interferential current on mechanical pain threshold and isometric peak torque after delayed onset muscle soreness induction in human hamstrings. Forty-one physically active healthy male volunteers aged 18?33 years were randomly assigned to one of two experimental groups: interferential current group (n = 21) or placebo group (n = 20). Both groups performed a bout of 100 isokinetic eccentric maximal voluntary contractions (10 sets of 10 repetitions) at an angular velocity of 1.05 rad · s?1 (60° · s?1) to induce muscle soreness. On the next day, volunteers received either an interferential current or a placebo application. Treatment was applied for 30 minutes (4 kHz frequency; 125 μs pulse duration; 80?150 Hz bursts). Mechanical pain threshold and isometric peak torque were measured at four different time intervals: prior to induction of muscle soreness, immediately following muscle soreness induction, on the next day after muscle soreness induction, and immediately after the interferential current and placebo application. Both groups showed a reduction in isometric torque (P < 0.001) and pain threshold (P < 0.001) after the eccentric exercise. After treatment, only the interferential current group showed a significant increase in pain threshold (P = 0.002) with no changes in isometric torque. The results indicate that interferential current was effective in increasing hamstrings mechanical pain threshold after eccentric exercise, with no effect on isometric peak torque after treatment.  相似文献   

3.
Abstract

The present investigation verified that strength is improved by a training programme consisting of repetitions of maximal isometric voluntary co-contractions without increasing co-activations during contractions against external resistances. Ten participants performed 12 training sessions (four sets of 6 × 4 second maximal isometric co-contraction of the elbow flexor and extensors, 3 days a week for 4 weeks). Surface electromyograms of triceps and biceps brachii were collected during maximal voluntary isometric elbow flexion and extension against a force transducer. Maximal voluntary isometric force increased significantly after training, by 13.8 ± 6.0% (extension) and 9.6 ± 9.5% (flexion), but the observed increases in EMG of agonist muscles during maximal voluntary contraction were not significant. No significant changes in the levels of co-activation of the elbow flexors and extensors were observed. No significant change was observed for all the parameters in a control group of ten participants. These results indicated that the strength improvements after co-contraction training occur without increases in co-activation level.  相似文献   

4.
Abstract

The aim of this study was to examine the relationship between shoulder alignment and elbow angle during the delivery action of fast-medium bowlers. The elbow and upper trunk alignment were recorded for 13 high-performance bowlers (mean age 20 years) using a 12-camera Vicon motion analysis system operating at 250 Hz. The three highest velocity trials for “good” and “short” length deliveries were analysed. Results showed that bowlers with a more front-on shoulder alignment at back-foot impact and when the upper arm was horizontal to the ground experienced a significantly greater elbow flexion – extension range when compared with those who had a more side-on orientation at the same point in the delivery action. Bowlers with greater shoulder counter-rotation also recorded higher elbow flexion and subsequently extension during the period from upper arm horizontal to ball release. Shoulder alignment and elbow angles were similar for “short” and “good” length deliveries. It was concluded that bowlers with a more front-on shoulder orientation at back-foot impact demonstrated a higher elbow extension from upper arm horizontal to ball release and are therefore more likely to infringe International Cricket Council elbow tolerance levels, compared with those who adopt a more side-on shoulder orientation at back-foot impact.  相似文献   

5.
Abstract

The aim of this study was to examine the effect of concentric warm-up exercise on eccentrically induced changes in muscle strength, range of motion, and soreness of the elbow flexors. Ten resistance-exercise naïve participants performed intermittent incremental eccentric actions (42 in total) of the elbow flexor muscles of each arm to induce muscle damage. The arms of each participant were randomly assigned either to a pre-eccentric exercise warm-up involving intermittent concentric exercise (warm-up) or no prior exercise (control). Strength, range of motion, and ratings of soreness were recorded before and 1, 2, 3, 4, and 7 days after exercise. Strength, range of motion, and soreness during muscular movements changed over time (P at most 0.01; Cohen's d at least 0.51, medium). There was an interaction (P < 0.001) for strength, showing a smaller reduction after exercise for warm-up than control (P < 0.001, d = 2.44, large effect). The decreased range of motion was less for warm-up than control for the arm while extended (P < 0.001), flexed (P = 0.002), and relaxed (P = 0.004). Muscle soreness was reduced for the warm-up group, while the muscle was flexed, extended, and relaxed compared with control (P < 0.001). The results demonstrate that a concentric warm-up exercise attenuates the reduction in loss of strength, range of motion, and muscle soreness after eccentric-exercise-induced muscle damage and might allow higher intensities of training to be performed.  相似文献   

6.
This study was undertaken to examine the acute effect of interferential current on mechanical pain threshold and isometric peak torque after delayed onset muscle soreness induction in human hamstrings. Forty-one physically active healthy male volunteers aged 18-33 years were randomly assigned to one of two experimental groups: interferential current group (n = 21) or placebo group (n = 20). Both groups performed a bout of 100 isokinetic eccentric maximal voluntary contractions (10 sets of 10 repetitions) at an angular velocity of 1.05 rad · s(-1) (60° · s(-1)) to induce muscle soreness. On the next day, volunteers received either an interferential current or a placebo application. Treatment was applied for 30 minutes (4 kHz frequency; 125 μs pulse duration; 80-150 Hz bursts). Mechanical pain threshold and isometric peak torque were measured at four different time intervals: prior to induction of muscle soreness, immediately following muscle soreness induction, on the next day after muscle soreness induction, and immediately after the interferential current and placebo application. Both groups showed a reduction in isometric torque (P < 0.001) and pain threshold (P < 0.001) after the eccentric exercise. After treatment, only the interferential current group showed a significant increase in pain threshold (P = 0.002) with no changes in isometric torque. The results indicate that interferential current was effective in increasing hamstrings mechanical pain threshold after eccentric exercise, with no effect on isometric peak torque after treatment.  相似文献   

7.
目的确定支链氨基酸是否能够降低运动造成的延迟性肌肉疼痛(DOMS)。方法采用双盲交叉实验设计。选取40名大学生(20女,20男)随机分成支链氨基酸组(n=20)和安慰剂组(n=20)。受试者进行200m自重蛙跳的训练用于引起DOMS,并且在服用支链氨基酸或安慰剂的同时,每隔24h,连续3天,对肌肉疼痛程度进行分级。在3周恢复期后,受试者再次进行支链氨基酸或安慰剂的干预实验,重复同样的运动程序,并在接下来的3天里进行肌肉疼痛的分级。结果与结论运动后24h,在女性受试者中,支链氨基酸补充使得DOMS降低与安慰剂组相比有显著的差异(p=0.015)。然而,对于女性受试者和男女受试者整体分析时则没有显著性差异。这种性别的差异可能与男女受试者单位体重补充支链氨基酸的剂量差异和女性雌激素对BCODH激酶代谢的影响有关。  相似文献   

8.
Abstract

In this study, we examined the long-term reductions in maximal isometric force (MIF) caused by a protocol of repeated maximal isometric contractions at long muscle length. Furthermore, we wished to ascertain whether the reductions in MIF are dependent on muscle length — that is, are the reductions in MIF more pronounced when the muscle contracts at a short length. The MIF of the elbow flexors of seven young male volunteers was measured at five different elbow angles between 50° and 160°. On a separate day, the participants performed 50 maximal voluntary isometric muscle contractions with the elbow flexors at a lengthened positions that is, with the shoulder hyperextended at 45° and the elbow joint fixed at 140°. Following this exercise, the MIF at the five elbow angles, range of motion, muscle soreness and plasma creatine kinase activity were measured at 24 h intervals for 4 days. On day 1, the decline in MIF was higher at the more acute elbow angles of 50° (42±8%) and 70° (39±8%; both P<0.01) than at 90° (26±4%) and 140° (16±3%; both P<0.01). No significant reduction in MIF was evident at an elbow angle of 160°. Maximal isometric force at an elbow angle of 140° was fully restored on day 3, whereas at an angle of 50° it remained depressed for the 4 day observation period. Restoration of MIF was a function of the elbow angle, with force recovery being less at the smaller angles. The range of motion was decreased by 14±2° on day 1 (P<0.01) and did not return to baseline values by day 4. Muscle soreness ratings remained significantly elevated for the 4 day period. Serum creatine kinase peaked on day 1 (522±129 IU, P<0.01) and decreased thereafter. We conclude that the disproportionate decrease in MIF at the small elbow angles and the length-specific recovery in MIF after repeated maximal isometric contractions at long muscle length may be explained by the presence of overstretched sarcomeres that increased in series compliance of the muscle, therefore causing a rightward shift of the force-length relationship.  相似文献   

9.
Lower limb isometric strength is a key parameter to monitor the training process or recognise muscle weakness and injury risk. However, valid and reliable methods to evaluate it often require high-cost tools. The aim of this study was to analyse the concurrent validity and reliability of a low-cost digital dynamometer for measuring isometric strength in lower limb. Eleven physically active and healthy participants performed maximal isometric strength for: flexion and extension of ankle, flexion and extension of knee, flexion, extension, adduction, abduction, internal and external rotation of hip. Data obtained by the digital dynamometer were compared with the isokinetic dynamometer to examine its concurrent validity. Data obtained by the digital dynamometer from 2 different evaluators and 2 different sessions were compared to examine its inter-rater and intra-rater reliability. Intra-class correlation (ICC) for validity was excellent in every movement (ICC > 0.9). Intra and inter-tester reliability was excellent for all the movements assessed (ICC > 0.75). The low-cost digital dynamometer demonstrated strong concurrent validity and excellent intra and inter-tester reliability for assessing isometric strength in the main lower limb movements.  相似文献   

10.
The purpose of this study was to measure the contributions of the motions of body segments and joints to racquet head speed during the tennis serve. Nine experienced male players were studied using three-dimensional film analysis. Upper arm twist orientations were calculated with two alternative methods using joint centres and skin-attached markers. The results showed that skin-attached markers could not be used to calculate accurate upper arm twist orientations due to skin movement, and that the use of joint centres produced errors of more than 20 degrees in the upper arm twist orientation when the computed elbow flexion/extension angle exceeded 135 degrees in the final 0.03 s before impact. When there were large errors in the upper arm twist orientation, it was impossible to obtain accurate data for shoulder or elbow joint rotations about any axis. Considering only the contributors that could be measured within our standards of acceptable error, the approximate sequential order of main contributors to racquet speed between maximum knee flexion and impact was: shoulder external rotation, wrist extension, twist rotation of the lower trunk, twist rotation of the upper trunk relative to the lower trunk, shoulder abduction, elbow extension, ulnar deviation rotation, a second twist rotation of the upper trunk relative to the lower trunk, and wrist flexion. The elbow extension and wrist flexion contributions were especially large. Forearm pronation made a brief negative contribution. Computed contributions of shoulder internal rotation, elbow extension and forearm pronation within the final 0.03 s before impact were questionable due to the large degree of elbow extension. Near impact, the combined contribution of shoulder flexion/extension and abduction/adduction rotations to racquet speed was negligible.  相似文献   

11.
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.  相似文献   

12.
  相似文献   

13.
Abstract

In this study, we wished to determine whether a warm-up exercise consisting of 100 submaximal concentric contractions would attenuate delayed-onset muscle soreness and decreases in muscle strength associated with eccentric exercise-induced muscle damage. Ten male students performed two bouts of an elbow flexor exercise consisting of 12 maximal eccentric contractions with a warm-up exercise for one arm (warm-up) and without warm-up for the other arm (control) in a randomized, counterbalanced order separated by 4 weeks. Muscle temperature of the biceps brachii prior to the exercise was compared between the arms, and muscle activity of the biceps brachii during the exercise was assessed by surface integral electromyogram (iEMG). Changes in visual analogue scale for muscle soreness and maximal voluntary isometric contraction strength (MVC) of the elbow flexors were assessed before, immediately after, and every 24 h for 5 days following exercise, and compared between the warm-up and control conditions by a two-way repeated-measures analysis of variance. The pre-exercise biceps brachii muscle temperature was significantly (P<0.01) higher for the warm-up (35.8±0.2°C) than the control condition (34.4±0.2°C), but no significant differences in iEMG and torque produced during exercise were evident between conditions. Changes in muscle soreness and MVC were not significantly different between conditions, although these variables showed significant (P<0.05) changes over time. It was concluded that the warm-up exercise was not effective in mitigating delayed-onset muscle soreness and loss of muscle strength following maximal eccentric exercise.  相似文献   

14.
It is believed that sport massage after intensive exercise might improve power and perceptual recovery in athletes. However, few studies have been done in this area. This study aimed to examine the effect of massage on the performance of bodybuilders. Thirty experienced male bodybuilders were randomly assigned to either a massage group (n = 15) or a control group (n = 15). Both groups performed five repetition sets at 75–77% of 1RM of knee extensor and flexor muscle groups. The massage group then received a 30-min massage after the exercise protocol while the control group maintained their normal passive recovery. Criteria under investigation included: plasma creatine kinase (CK) level, agility test, vertical jump test, isometric torque test, and perception of soreness. All variables were measured over 6 time periods: baseline, immediately after the DOMS inducing protocol, right after the massage, and 24, 48, and 72 h after the massage. Both groups showed significant (P < .001) decreases in jumping, agility performance, and isometric torque, but significant (P < .001) increases in CK and muscle soreness levels. The massage group in general demonstrated a better recovery rate. As such, a post-exercise massage session can improve the exercise performance and recovery rate in male bodybuilders after intensive exercise.  相似文献   

15.
This study investigated the contribution of flexor muscles to the forearm through fatigue; therefore, the differences in forearm mechanisms on the pitching motion in fastball were analysed. Fifteen baseball pitchers were included in this study. Ultrasonographical examination of participants’ ulnar nerve in the cubital tunnel with the elbow extended and at 45°, 90° and 120° of flexion was carried. A three-dimensional motion analysis system with 14 reflective markers attached on participants was used for motion data collection. The electromyography system was applied over the flexor carpi ulnaris, flexor carpi radialis and extensor carpi radialis muscles of the dominant arm. Flexor carpi ulnaris muscle activity showed a significant difference during the acceleration phase, with a peak value during fastball post-fatigue (P = 0.02). Significant differences in the distance between ulnar nerve and medial condyle on throwing arm and non-throwing arm were observed as the distance increased with the elbow movement from 0° to 120° of flexion (P = 0.01). The significant increase of the flexor carpi ulnaris muscle activity might be responsible for maintaining the stability of the wrist joint. The increased diameter might compress the ulnar nerve and cause several pathological changes. Therefore, fatigue in baseball pitchers still poses a threat to the ulnar nerve because the flexor carpi ulnaris and flexor carpi radialis all originate from the medial side of the elbow, and the swelling tendons after fatigue might be a key point.  相似文献   

16.
Abstract

In the sport of cricket the objective of the “no-ball” law is to allow no performance advantage through elbow extension during ball delivery. However, recently it has been shown that even bowlers with actions that are considered within the law show some elbow extension. The objective of this study was to investigate: [1] the effect of elbow orientation during anatomical landmark digitisation and [2] the choice of upper arm tracking cluster on the measurement of elbow angles during cricket bowling.

We compared the mean elbow angles for four different elbow postures; with the joint flexed at approximately 130°, 90°, in full extension and with the elbow flexed with the humerus internally rotated, and two upper arm clusters in two different situations: [1] during a controlled movement of pure flexion-extension and [2] during cricket bowling. The digitised postures of the anatomical landmarks where the elbow was extended and at 90° of flexion were more repeatable than the other two postures. The recommendation of this study when analysing cricket bowling is to digitise the humeral epicondyles with the joint flexed at 90°, or in full extension, and to relate their positions to an upper arm cluster fixed close to the elbow.  相似文献   

17.
This modelling study sought to describe the relationships between elbow joint kinematics and wrist joint linear velocity in cricket fast bowlers, and to assess the sensitivity of wrist velocity to systematic manipulations of empirical joint kinematic profiles. A 12-camera Vicon motion analysis system operating at 250 Hz recorded the bowling actions of 12 high performance fast bowlers. Empirical elbow joint kinematic data were entered into a cricket bowling specific “Forward Kinematic Model” and then subsequently underwent fixed angle, angular offset and angle amplification manipulations. A combination of 20° flexion and 20° abduction at the elbow was shown to maximise wrist velocity within the experimental limits. An increased elbow flexion offset manipulation elicited an increase in wrist velocity. Amplification of elbow joint flexion–extension angular displacement indicated that, contrary to previous research, elbow extension range of motion and angular velocity at the time of ball release were negatively related to wrist velocity. Some relationships between manipulated joint angular waveforms and wrist velocity were non-linear, supporting the use of a model that accounts for the non-linear relationships between execution and outcome variables in assessing the relationships between elbow joint kinematics and wrist joint velocity in cricket fast bowlers.  相似文献   

18.
Cricket bowling is traditionally thought to be a rigid-arm motion, allowing no elbow straightening during the delivery phase. Conversely, research has shown that a perfectly rigid arm through delivery is practically unattainable, which has led to rule changes over the past years. The current rule requires a bowler not to increase the elbow angle by more than 15°, thus requiring a measurement to confirm legality in “suspect” bowlers. The aims of this study were to evaluate whether the current rule is maintained over a range of bowlers and bowling styles, and to ascertain whether other kinematics measures may better differentiate between legal and suspect bowling actions. Eighty-three bowlers of varying pace were analysed using reflective markers and a high-speed (240 Hz) eight-camera motion analysis system in a laboratory. The change in elbow segment angle (minimum angle between the arm and forearm), the change in elbow extension angle with respect to the flexion–extension axis of a joint coordinate system, and the elbow extension angular velocity at ball release were measured. We found that bowlers generally bowled within a change in elbow extension angle of 15°. However, this limit was unable to differentiate groups of bowlers from those who were suspected of throwing in the past. Improved differentiation was attained using the elbow extension angular velocity at ball release. The elbow extension angular velocity at ball release may be conceptually more valid than the elbow extension angle in determining which bowlers use the velocity-contributing mechanisms of a throw. Also, a high value of elbow extension angular velocity at ball release may be related to the visual impression of throwing. Therefore, it is recommended that researchers and cricket legislators examine the feasibility of specifying a limit to the elbow extension angular velocity at ball release to determine bowling legality.  相似文献   

19.
The aim of this study was to examine the effects of a prophylactic dose of a local, transcutaneously administered, non-steroidal anti-inflammatory drug on muscle soreness, muscle damage and sprinting performance in young trained males. Twenty-five subjects aged 19+/-3 years, actively participating in rugby union and field hockey, were familiarized with the test procedure and then divided at random into an experimental group (n = 13) and a control group (n = 12). The experimental group received two patches, each containing 40 mg flurbiprofen (TransAct LAT), 12 h before an exercise bout designed to produce delayed-onset soreness (DOMS). The control group received identical non-medicated placebo patches at the same time. Delayed-onset muscle soreness was induced by an exercise protocol consisting of drop jumps (seven sets of 10 repetitions). Serum creatine kinase activity, muscle soreness, muscle girth and acceleration in a maximal sprint over 30 m were measured before the induction of DOMS and at 12, 24, 48 and 72 h thereafter. Plasma lactate concentration was measured 3 min after the 30-m sprint tests. Subjects in both groups had significantly more pain at 24 and 48 h compared with at 12 and 72 h (P < 0.05; Friedman two-way analysis of variance). Thigh girth and serum creatine kinase did not change throughout the experiment. Although plasma lactate concentrations were elevated after the 30-m sprint, there were no differences between groups or as a result of DOMS. The greatest acceleration occurred between 5 and 10 m. This was not affected by the anti-inflammatory drug or DOMS. In conclusion, the aetiology of the DOMS induced in the trained subjects in this study seems to be independent of inflammatory processes or, more specifically, of increases in prostaglandin synthesis in the muscles.  相似文献   

20.
The purpose of this study was to investigate the effects of using an internal versus external focus of attention during resistance training on muscular adaptations. Thirty untrained college-aged men were randomly assigned to an internal focus group (INTERNAL) that focused on contracting the target muscle during training (n?=?15) or an external focus group (EXTERNAL) that focused on the outcome of the lift (n?=?15). Training for both routines consisted of 3 weekly sessions performed on non-consecutive days for 8 weeks. Subjects performed 4 sets of 8–12 repetitions per exercise. Changes in strength were assessed by six repetition maximum in the biceps curl and isometric maximal voluntary contraction in knee extension and elbow flexion. Changes in muscle thickness for the elbow flexors and quadriceps were assessed by ultrasound. Results show significantly greater increases in elbow flexor thickness in INTERNAL versus EXTERNAL (12.4% vs. 6.9%, respectively); similar changes were noted in quadriceps thickness. Isometric elbow flexion strength was greater for INTERNAL while isometric knee extension strength was greater for EXTERNAL, although neither reached statistical significance. The findings lend support to the use of a mind–muscle connection to enhance muscle hypertrophy.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号