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1.
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   

2.
Delayed-onset muscle soreness refers to the skeletal muscle pain that is experienced following eccentric exercise. The aim of the present study was to examine the physiological effects of physical activity with or without ibuprofen on delayed onset muscle soreness. Forty-four non-athletic male volunteers (age 24.3?±?2.4 years) were randomly assigned to one of four groups: physical activity (n = 11), ibuprofen (n = 11), physical activity and ibuprofen (combination, n = 11), or control (n = 11). The physical activity programme comprised 5?min of walking and jogging, 10?min of static stretching of the hands and shoulder girdle, and 5?min of concentric movements with sub-maximal contractions. The total amount of ibuprofen consumed by a single individual was 2800?mg; this was taken from 1?h before the eccentric actions up to 48?h after it. Delayed onset muscle soreness was induced by performing 70 eccentric contractions of the biceps muscle of the non-dominant side on a modified arm curl machine. Perceived muscle soreness, maximal eccentric contraction, creatine kinase enzyme activity and elbow range of motion were assessed 1?h before and 1, 24 and 48?h after the eccentric actions. The results indicated that, after the eccentric actions, soreness increased (P?<?0.001) across time in all groups, with the highest values being recorded at 24?h. At 24 and 48?h, greater soreness (P <?0.001) was observed in the control group than in the physical activity and combination groups. After the eccentric actions, creatine kinase increased and was elevated (P?<?0.001) compared with baseline in all groups, with values returning to baseline in the physical activity and combination groups by 48?h. However, creatine kinase in the control and ibuprofen groups was still significantly higher than at baseline after 48?h. Creatine kinase was higher (P?<?0.001) in the control group than in physical activity and combination groups at 24 and 48?h. There was also a reduction (P?<?0.001) in elbow range of motion across time. This reduction in elbow range of motion was greater (P?<?0.001) in the control and ibuprofen groups than in the physical activity and combination groups at 1, 24 and 48?h. The reduction in maximum eccentric contraction was greater (P?<?0.001) in the control and ibuprofen groups than in the physical activity group at 24 and 48?h and the combination group at 48?h. In conclusion, the results add to our understanding of the effects of physical activity and the combination of physical activity and ibuprofen in reducing the severity of muscle soreness induced by eccentric exercise. Physical activity conducted before eccentric exercise alleviates muscle soreness. Our results indicate that physical activity with or without ibuprofen helps to prevent delayed-onset muscle soreness.  相似文献   

3.
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 naive 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?相似文献   

4.
Delayed-onset muscle soreness refers to the skeletal muscle pain that is experienced following eccentric exercise. The aim of the present study was to examine the physiological effects of physical activity with or without ibuprofen on delayed onset muscle soreness. Forty-four non-athletic male volunteers (age 24.3 +/- 2.4 years) were randomly assigned to one of four groups: physical activity (n = 11), ibuprofen (n = 11), physical activity and ibuprofen (combination, n = 11), or control (n = 11). The physical activity programme comprised 5 min of walking and jogging, 10 min of static stretching of the hands and shoulder girdle, and 5 min of concentric movements with sub-maximal contractions. The total amount of ibuprofen consumed by a single individual was 2800 mg; this was taken from 1 h before the eccentric actions up to 48 h after it. Delayed onset muscle soreness was induced by performing 70 eccentric contractions of the biceps muscle of the non-dominant side on a modified arm curl machine. Perceived muscle soreness, maximal eccentric contraction, creatine kinase enzyme activity and elbow range of motion were assessed 1 h before and 1, 24 and 48 h after the eccentric actions. The results indicated that, after the eccentric actions, soreness increased (P < 0.001) across time in all groups, with the highest values being recorded at 24 h. At 24 and 48 h, greater soreness (P < 0.001) was observed in the control group than in the physical activity and combination groups. After the eccentric actions, creatine kinase increased and was elevated (P < 0.001) compared with baseline in all groups, with values returning to baseline in the physical activity and combination groups by 48 h. However, creatine kinase in the control and ibuprofen groups was still significantly higher than at baseline after 48 h. Creatine kinase was higher (P < 0.001) in the control group than in physical activity and combination groups at 24 and 48 h. There was also a reduction (P < 0.001) in elbow range of motion across time. This reduction in elbow range of motion was greater (P < 0.001) in the control and ibuprofen groups than in the physical activity and combination groups at 1, 24 and 48 h. The reduction in maximum eccentric contraction was greater (P < 0.001) in the control and ibuprofen groups than in the physical activity group at 24 and 48 h and the combination group at 48 h. In conclusion, the results add to our understanding of the effects of physical activity and the combination of physical activity and ibuprofen in reducing the severity of muscle soreness induced by eccentric exercise. Physical activity conducted before eccentric exercise alleviates muscle soreness. Our results indicate that physical activity with or without ibuprofen helps to prevent delayed-onset muscle soreness.  相似文献   

5.
Abstract

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   

6.
This investigation examined effects of two exercise modes (barbell, BB; bodyweight suspension, BWS) on muscle activation, resistance load, and fatigue. During session one, nine resistance-trained males completed an elbow flexion one-repetition maximum (1RM). During sessions two and three, subjects completed standing biceps curls to fatigue at 70% 1RM utilizing a randomized exercise mode. Surface electromyography (sEMG) recorded muscle activation of the biceps brachii, triceps brachii, anterior deltoid, posterior deltoid, rectus abdominis, and erector spinae. BWS resistance load was measured using a force transducer. Standing maximal voluntary isometric contractions of the elbow flexors recorded at 90° were used to determine the isometric force decrement and rate of fatigue (ROF) during exercise. sEMG and resistance load data were divided into 25% contraction duration bins throughout the concentric phase. BWS resulted in a 67.7?±?7.4% decline in resistance load throughout the concentric phase (p?≤?0.05). As a result, BB elicited higher mean resistance loads (31.4?±?4.0?kg) and biceps brachii sEMG (84.7?±?27.8% maximal voluntary isometric contractions, MVIC) compared with BWS (20.4?±?3.4?kg, 63.4?±?21.6% MVIC). No difference in rectus abdominis or erector spinae sEMG was detected between exercise modes. Isometric force decrement was greater during BWS (?21.7?±?7.0?kg) compared with BB (?14.9?±?4.7?kg); however, BB (?3.0?±?0.8?kg/set) resulted in a steeper decline in ROF compared with BWS (?1.7?±?0.6?kg/set). The variable resistance loading and greater isometric force decrement observed suggest that select BWS exercises may resemble variable resistance exercise more than previously considered.  相似文献   

7.
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   

8.
主动肌和拮抗肌功能转变瞬间的肌电平均功率频率变化   总被引：2，自引：1，他引：1  
目的:通过对主动肌和拮抗肌功能转变瞬间肌电平均功率频率的观察,探讨中枢控制因素在决定MPF变化中的独立性作用.方法:10名健康男性志愿者在完成60%MVC强度的疲劳性等长屈肘运动负荷试验后,瞬间转变肌肉工作性质,完成60%MVC强度的疲劳性等长伸肘运动,分别记录肱二头肌和肱三头肌的sEMG信号,观察两次疲劳试验以及瞬间转变过程中肌电MPF等sENG指标变化.结果:等长屈肘和等长伸肘快速转变的瞬间,主动肌和拮抗肌MPF等各项sEMG信号分析指标均发生了显著性改变,表现出明显的跃变现象;无论是转变之前,还是转变之后的等长疲劳试验过程中,主动肌与拮抗肌的MPF、C(n)和%DEF均表现出类似的变化规律,而拮抗肌AEMG则维持相对恒定.结论:中枢运动控制是导致疲劳过程中MPF单调递减变化的独立性作用因素,其可能的作用机制是CNS将主动肌与拮抗肌作为一组控制肌群实施同步控制.  相似文献   

9.
Cryotherapy is an effective treatment for acute sports injury to soft tissue, although the effect of cryotherapy on exercise-induced muscle damage is unclear. The aim of this study was to assess the effects of cold water immersion on the symptoms of exercise-induced muscle damage following strenuous eccentric exercise. After performing a bout of damage-inducing eccentric exercise (eight sets of five maximal reciprocal contractions at 0.58 rad x s(-1)) of the elbow flexors on an isokinetic dynamometer, 15 females aged 22.0+/-2.0 years (mean +/- s) were allocated to a control group (no treatment, n = 7) or a cryotherapy group (n = 8). Subjects in the cryotherapy group immersed their exercised arm in cold water (15 degrees C) for 15 min immediately after eccentric exercise and then every 12 h for 15 min for a total of seven sessions. Muscle tenderness, plasma creatine kinase activity, relaxed elbow angle, isometric strength and swelling (upper arm circumference) were measured immediately before and for 3 days after eccentric exercise. Analysis of variance revealed significant (P < 0.05) main effects for time for all variables, with increases in muscle tenderness, creatine kinase activity and upper arm circumference, and decreases in isometric strength and relaxed elbow angle. There were significant interactions (P<0.05) of group x time for relaxed elbow angle and creatine kinase activity. Relaxed elbow angle was greater and creatine kinase activity lower for the cryotherapy group than the controls on days 2 and 3 following the eccentric exercise. We conclude that although cold water immersion may reduce muscle stiffness and the amount of post-exercise damage after strenuous eccentric activity, there appears to be no effect on the perception of tenderness and strength loss, which is characteristic after this form of activity.  相似文献   

10.
The aim of this study was to examine neuromuscular variables contributing to differences in force loss after participants were exposed to the same relative bout of eccentric exercise. Thirty-six males performed 50 maximal eccentric contractions of the elbow flexors and were stratified into high responders (n?=?10) and low responders (n?=?10) based on force loss 36 h after exercise. Maximal voluntary isometric contractions (MVCs) and electromyography (EMG) were measured at baseline and 36 h after exercise. During eccentric exercise, mean peak torque, mean end-range torque from the final 25% of each trial and total angular impulse were computed over 25 contractions in each of two bouts. The slope of the change in these values for each 25 eccentric contractions was calculated for each participant using linear regression. At baseline, MVC was not different between groups (low responders: 97.0?±?9.6 N?·?m; high responders: 82.7?±?6.4 N?·?m; P?=?0.08). High responders demonstrated a 68% (range 62-78%) reduction in MVC and low responders a 39% (29-48%) reduction after exercise. Peak torque, end-range torque and total angular impulse were 13%, 40% and 33% higher, respectively, in the low than in the high responders (peak torque: P?=?0.0002; end-range torque: P?<?0.0001; total angular impulse: P?<?0.001). The rate of decline in peak torque slope was greater in high than in low responders (P?=?0.044). In conclusion, lower peak torque, end-range torque and total angular impulse during eccentric contractions and a greater peak torque slope may identify high responders to eccentric exercise.  相似文献   

11.
It has previously been shown that females incur less muscle damage than males after strenuous exercise, but limited data are available for humans. To determine possible differences between the sexes in humans, the response to high-force eccentric exercise was examined in a large sample of women (n = 83) and men (n = 82). The participants performed a bout of eccentric exercise of the elbow flexors consisting of 70 maximal repetitions. Isometric strength, resting elbow angle and muscle soreness were measured before, immediately after (except soreness) and then daily for 7 days after exercise. There was a significant loss in strength among both groups (69% for women and 63% for men) (P?0.01) immediately after exercise; at 168 h post-exercise, women still had a 27% strength loss and men had a 24% strength loss. No significant difference in strength loss or recovery rate was found between men and women. Soreness reached peak values 32-48 h post-exercise (P?0.01), with no significant difference between men and women. Range of motion decreased significantly until 3 days after exercise (14.6° or 0.255 rad loss for women; 12.2° or 0.213 rad loss for men) (P?0.01); at 168 h post-exercise, the women and men still showed a loss of 4.8° (0.084 rad) and 4.0° (0.07 rad), respectively. There was a significant interaction of sex x time (P?0.01); a post-hoc test indicated that the women experienced a greater loss in range of motion at 72 h than men and this difference was maintained to 168 h post-exercise (P?0.01). Thus, our results do not support the contention that women have a lower response to eccentric exercise than men.  相似文献   

12.
文烨 《中国体育科技》2012,48(4):71-77,89
目的:研究优秀乒乓球运动员和普通在校大学生肘关节拮抗肌活动在等动屈伸过程中的差异。方法:以8名优秀乒乓球运动员和8名普通高校大学生为研究对象,利用Biodex等动测试仪和Noraxon表面肌电仪记录上肢肘关节等动屈伸过程中作为拮抗肌的肱二头肌和肱三头肌的力量特征和表面肌电信号特征。肘关节伸肌和屈肌分别在最大等长收缩、15°/s、30°/s、60°/s、120°/s、180°/s、240°/s条件下进行3次最大等动离心屈伸运动。以标准化的均方根振幅(RMS)和标准化的峰值力矩作为评价指标。结果:对于大学生和优秀乒乓球运动员来说,随着肘关节速度的增加,两组受试者的屈伸肌力矩都呈下降趋势,大学生表现为速度大于60°/s时伸肌力矩大于屈肌力矩(P<0.05),优秀乒乓球运动员表现为伸肌力矩低于屈肌力矩,但没有统计学差别(P>0.05)。大学生和优秀乒乓球运动员都表现为在向心收缩时不同速度下随着主动肌力矩下降,拮抗肌激活水平表现为逐渐增高,且所有线性拟合系数r2>0.7。优秀乒乓球运动员拮抗肌肱三头肌的激活水平(在MVC时:10.1%±5.2%,240°/s时:15.1%±6.6%)要显著低于普通高校大学生(MVC时:29.3%±8.8%,240°/s时:38.0%±15.1%)。而作为拮抗肌的肱二头肌激活水平在普通大学生和优秀乒乓球运动员之间没有统计学差异(P>0.05)。优秀乒乓球运动员拮抗肌/主动肌肌电活动比要显著低于普通大学生(P<0.05)。结论:与普通大学生相比,优秀乒乓球运动员肘关节拮抗肌肱三头肌的激活水平要更低,这可能是优秀乒乓球运动员对肘关节周围肌肉进行长期训练的结果。而两者拮抗肌肱二头肌激活水平没有统计学差异,其原因可能是由于两者在日常活动中肱二头肌作为拮抗肌经常为了克服地心引力受到同样的刺激造成的。  相似文献   

13.
The first purpose of this study was to determine a possible explanation for the variability in the response to eccentric exercise by having participants repeat the same exercise 1 year apart. The second purpose was to examine whether initial injury in response to eccentric exercise was associated with the extent of the repeated bout effect (RBE). Male students performed 30 eccentric contractions (ECC) of the elbow flexors using a dumbbell set at 80% of the pre-exercise maximal isometric force (MIF). Participants were then classified into low (LR; n = 6), medium (MR; n = 6), high (HR; n = 5), and higher (HrR; n = 7) based on the increase in blood creatine kinase (CK) activity. A year later, participants repeated this exercise (ECC30). Four days after ECC30, participants performed 70 eccentric contractions (ECC70). Range of motion, MIF, upper arm circumference, soreness, and blood CK activity were measured before and up to 9 days after each bout. The change in the criterion measures following ECC and ECC30 were similar for each group. There were no further changes in all parameters after ECC70 for MR, HR, and HrR, although there was a small increase in CK after ECC70 for LR. LR showed a smaller RBE after ECC70 compared with the other groups. It is concluded that participants who exercised 1 year apart showed remarkably similar responses between the bouts. The extent of the RBE following the second bout for the LR group is less for participants who demonstrate the least evidence of muscle damage after a first exercise bout.  相似文献   

14.
Abstract

This study investigated whether hot pack treatment could provide prophylactic effects on muscle damage induced by eccentric exercise of the wrist extensors. Twenty-eight healthy men (age 21±1 years, weight 65±16 kg, height 171±6 cm) were randomly placed into hot pack (n = 14) and control (n = 14) groups. All participants performed an exercise consisting of 300 maximal eccentric contractions of the wrist extensors of the non-dominant arm using an isokinetic dynamometer. A hot pack was applied for 20 min to the wrist extensors of the exercised arm before the exercise for the hot pack group. The control group received no treatment before the exercise. Measured variables included pain intensity assessed by a visual analogue scale and a modified Likert's scale, cold thermal pain threshold, pressure pain threshold (PPT), range of motion in active wrist flexion (ROM-AF) and extension (ROM-AE), range of motion in passive wrist flexion (ROM-PF) and extension (ROM-PE), grip strength, and wrist extension strength. Changes in these variables before, immediately after, and 1 to 8 days following the exercise were compared between groups by a two-way repeated measures ANOVA. All outcome measures from both groups (except for the cold thermal pain threshold of the hot pack group) demonstrated a significant change within the first 2–3 days following exercise. Significant differences between groups were only found at a single point in time for PPT, ROM-PF, ROM-PE and ROM-AE, and the changes were smaller for the hot pack group in comparison to the control group. These results suggest that the prophylactic effects of hot pack treatment on eccentric exercise-induced muscle damage of the wrist extensors are limited.  相似文献   

15.
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   

16.
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   

17.
Post-exercise cryotherapy treatments are typically short duration interventions. This study examined the efficacy of prolonged cooling using phase change material (PCM) on strength loss and pain after eccentric exercise. Eight adults performed 120 bilateral eccentric quadriceps contractions (90% MVC). Immediately afterwards, frozen PCM packs (15°C) were placed over the quadriceps, with room temperature PCM packs on the contralateral quadriceps. Skin temperature was recorded continually (6 h PCM application). Isometric quadriceps strength and soreness were assessed before, 24, 48, 72 and 96 h post-exercise. The protocol was repeated 5 months later, with room temperature PCM applied to both legs. There were three treatments: legs treated with 15°C PCM packs (direct cooling), legs treated with room temperature PCM packs contralateral to the 15°C PCM packs (systemic cooling), and legs tested 5 months later both treated with room temperature PCM packs (control). Skin temperature was 9°C–10°C lower with direct cooling versus systemic cooling and control (P < 0.01). Strength loss and soreness were less (P < 0.05) with direct cooling versus systemic cooling and control (strength 101%, 94%, 93%, respectively; pain 1.0, 2.3, 2.7, respectively). Six hours of PCM cooling was well tolerated and reduced strength loss and pain after damaging exercise.  相似文献   

18.
The first purpose of this study was to determine a possible explanation for the variability in the response to eccentric exercise by having participants repeat the same exercise 1 year apart. The second purpose was to examine whether initial injury in response to eccentric exercise was associated with the extent of the repeated bout effect (RBE). Male students performed 30 eccentric contractions (ECC) of the elbow flexors using a dumbbell set at 80% of the pre-exercise maximal isometric force (MIF). Participants were then classified into low (LR; n=6), medium (MR; n=6), high (HR; n=5), and higher (HrR; n=7) based on the increase in blood creatine kinase (CK) activity. A year later, participants repeated this exercise (ECC30). Four days after ECC30, participants performed 70 eccentric contractions (ECC70). Range of motion, MFI upper arm circumference, soreness, and blood CK activity were measured before and up to 9 days after each bout. The change in the criterion measures following ECC and ECC30 were similar for each group. There were no further changes in all parameters after ECC70 for MR, HR, and HrR, although there was a small increase in CK after ECC70 for LR. LR showed a smaller RBE after ECC70 compared with the other groups. It is concluded that participants who exercised 1 year apart showed remarkably similar responses between the bouts. The extent of the RBE following the second bout for the LR group is less for participants who demonstrate the least evidence of muscle damage after a first exercise bout.  相似文献   

19.
运动性肌肉疲劳过程中主动肌与拮抗肌sEMG相干性分析   总被引：3，自引：1，他引：2  
目的:通过静态疲劳负荷实验过程中主动肌与拮抗肌sEMG的相干性分析探索运动性肌肉疲劳过程中中枢神经系统对主动肌与拮抗肌共神经输入(common neural inputs)同步支配的变化特征。方法:以10名健康男性青年志愿者为研究对象,记录受试者以50%MVC负荷强度静态屈肘运动诱发肌肉疲劳过程中主动肌肱二头肌与拮抗肌肱三头肌的sEMG,为考查疲劳因素对相干性分析结果的影响作用,对记录的sEMG按运动持续时间平均分为两段,分别对两段sEMG进行相干性分析处理。结果:在疲劳负荷实验过程中,肱二头肌与肱三头肌MF指标随运动持续时间表现出显著性的单调递减变化趋势。从相干性分析结果看,在beta频段和gamma频段内,运动后半段肱二头肌与肱三头肌sEMG相干函数值要明显小于运动前半段,而tremor频段内无显著性差异。结论:在50%MVC静态负荷屈肘运动致肌肉疲劳过程中,随着负荷运动持续时间的增加,中枢神经系统对主动肌肱二头肌与拮抗肌肱三头肌共神经输入同步支配下降,这可能是由于主动肌与拮抗肌脊髓运动神经元兴奋性及运动皮层对脊髓运动神经元激活能力随疲劳发展的下降不同步性及为维持既定的收缩负荷,中枢神经系统对主动肌与拮抗肌运动单位的募集策略采取不同的调节方式造成的。  相似文献   

20.
It has previously been shown that females incur less muscle damage than males after strenuous exercise, but limited data are available for humans. To determine possible differences between the sexes in humans, the response to high-force eccentric exercise was examined in a large sample of women (n = 83) and men (n = 82). The participants performed a bout of eccentric exercise of the elbow flexors consisting of 70 maximal repetitions. Isometric strength, resting elbow angle and muscle soreness were measured before, immediately after (except soreness) and then daily for 7 days after exercise. There was a significant loss in strength among both groups (69% for women and 63% for men) (P < 0.01) immediately after exercise; at 168 h post-exercise, women still had a 27% strength loss and men had a 24% strength loss. No significant difference in strength loss or recovery rate was found between men and women. Soreness reached peak values 32-48 h post-exercise (P < 0.01), with no significant difference between men and women. Range of motion decreased significantly until 3 days after exercise (14.6 degrees or 0.255 rad loss for women; 12.2 degrees or 0.213 rad loss for men) (P < 0.01); at 168 h post-exercise, the women and men still showed a loss of 4.8 degrees (0.084 rad) and 4.0 degrees (0.07 rad), respectively. There was a significant interaction of sex x time (P < 0.01); a post-hoc test indicated that the women experienced a greater loss in range of motion at 72 h than men and this difference was maintained to 168 h post-exercise (P < 0.01). Thus, our results do not support the contention that women have a lower response to eccentric exercise than men.  相似文献   

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