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1.
ABSTRACT

Purpose: The present study aimed to compare the vertical ground reaction force responses during the performance of the stationary running water-based exercise with and without equipment at different cadences by elderly women. Method: Nineteen elderly women (age: 68.6 ± 5.0 years; body mass: 69.0 ± 9.5 kg; height: 154.9 ± 5.6 cm) completed one session consisting of the performance of the water-based stationary running with elbow flexion and extension immersed to the xiphoid process depth. The exercise was performed in three conditions, without equipment, with water-floating and with water-resistance equipment, at three cadences (80 b·min?1, 100 b·min?1 and maximal) in a randomized order. Peak and impulse of vertical ground reaction force were collected during the exercise using an underwater force plate. Repeated measures two-way ANOVA was used (α = 0.05). Results: Peak vertical ground reaction force (p < .001) and impulse (p ≤ 0.002) resulted in lower values for the water-floating use (0.42–0.48 BW and 0.07–0.13 N.s/BW) in comparison to the water-resistance equipment use (0.46–0.60 BW and 0.09–0.16 N.s/BW) and to the non-use of equipment (0.45–0.60 BW and 0.07–0.17 N.s/BW), except for the impulse at the maximal cadence. In addition, peak vertical ground reaction force at 80 b·min?1 (p = .002) and impulse at the maximal cadence (p < .001) showed lower values compared to the other cadences. Conclusion: The use of water-floating equipment minimizes the vertical ground reaction force during the stationary running water-based exercise performed by elderly women regardless of the cadence.  相似文献   

2.
The aim of this study was to examine the effects of barbell load on countermovement vertical jump (CMJ) power and net impulse within a theoretically valid framework, cognisant of the underpinning force, temporal, and spatial components. A total of 24 resistance-trained rugby union athletes (average ± SD: age: 23.1 ± 3.4 years; height: 1.83 ± 0.05 m; body mass (BM): 91.3 ± 10.5 kg) performed maximal CMJ under 5 experimental conditions in a randomised, counterbalanced order: unloaded, and with additional loads of 25%, 50%, 75%, and 100% of BM. Peak power and average power were maximised during the unloaded condition, both decreasing significantly (P < 0.05) as load increased. Net impulse was maximised with 75% of BM, which was significantly greater (P < 0.05) than the unloaded and 100% of BM conditions. Net mean force and mean velocity were maximised during the unloaded condition and decreased significantly (P < 0.05) as load increased, whereas phase duration increased significantly (P < 0.05) as load increased. As such, the interaction between barbell load and the underpinning force, time, and displacement components should be considered by strength and conditioning coaches when prescribing barbell loads.  相似文献   

3.
Reaction time and response time are considered important abilities and can potentially affect combat performance. This study investigated the effect of a specific fatigue protocol on reaction time, response time, performance time, and kick impact. Seven male athletes reported to the laboratory on two different days. During day one, athletes performed a specific progressive taekwondo test, and on day two, a protocol for determining reaction time, response time, performance time, and kick impact before and after a time to exhaustion test at an intensity level corresponding to the maximal kick frequency obtained during the specific progressive taekwondo test. Muscle activation from rectus femoris and kick impact of the preferred limb were assessed. No differences were observed for response time and performance time. However, kick impact decreased (43 ± 27 to 13 ± 10 g, p < 0.01) while reaction time increased (145 ± 51 to 223 ± 133 ms, p < 0.05). Moderate correlation was observed between kick impact and response time (r = 0.565; p < 0.01), and kick impact and performance time (r = 0.494; p < 0.05). Results indicate that coaches and athletes may use taekwondo training programmes on coordination-based exercises leading to improve response time and to reduce fatigue effects in order to improve technique effectiveness and enhance the possibilities of scoring in a competitive situation.  相似文献   

4.
To investigate characteristic upper limb muscle use between two common tug of war (TOW) gripping styles, 20 elite athletes from two high school TOW teams were recruited. Under conditioned attack pulling (with 90% maximal force) on a tug machine, participants used their own habitual gripping style to pull for five 15-s trials. Force and kinematic measurements showed a significantly better force performance and higher centre-of-gravity tilting angle with the gripping style one than with the gripping style two (GS2) (both p < 0.05). However, an overall higher and more symmetrical muscle activation detected by normalised surface electromyography signal amplitude was found in the GS2 group (both p < 0.05). In both groups, the distal and flexor muscles were more activated than the proximal and extensor muscles, respectively (p < 0.05). Higher co-contraction ratio was found in the wrist joints of the latter arm in both groups (p < 0.05). As higher muscle activation level and co-contraction indicate higher muscle and joint injury incidences, we suggest that gripping style factors should be considered in training to prevent muscle and joint injury. Future study concerning segmental kinematics, ground reaction force, moment arm and muscle endurance during the defence phase are warranted.  相似文献   

5.
ABSTRACT

Purpose: To evaluate vascular function and its relationship to cardiorespiratory fitness in professional handball athletes. Method: We examined 30 male professional handball athletes (age 27 ± 4 y) and 10 male sedentary controls (age 26 ± 5 y) at rest. The workup included exercise testing via ergometry. To assess vascular function, a validated electronic model of the arterial tree (vasc assist 2®) was used. It replicates noninvasively acquired pulse pressure waves by modulating the relevant functional parameters of compliance, resistance, inertia, pressure, and flow. The maximum oxygen uptake (VO2max) was estimated using the validated heart rate ratio method. Results: Athletes had a significantly lower systolic and diastolic central blood pressure (cBP) compared to controls (102 ± 9/60 ± 9 vs. 110 ± 8/74 ± 9 mmHg, p < .01), whereas aortic pulse wave velocity (PWV) (6.2 ± 0.8 vs. 6.3 ± 0.5 m/s, p = .45) and augmentation index at a heart rate of 75 (Aix@75) (?4 ± 12 vs. ?13 ± 16%, p = .06) were not different. Resistance index (R) (15.9 ± 4.4 vs. 10.6 ± 0.6, p = .001) and maximum power output (MPO) (3.55 ± 0.54 vs. 2.46 ± 0.55 Watt/kg, p < .001) were significantly higher in athletes compared to controls. We found no relevant correlation between MPO, resting heart rate, PWV, Aix@75, and cBP. A higher VO2max (p = .02) and a lower R (p < .01) were significant predictors of a higher MPO in athletes. Conclusion: R had an independent and strong correlation to MPO in athletes, which might help to disentangle the contribution of aerobic capacity and arterial function to physical power.  相似文献   

6.
The aim of this study was to assess the effect of a unilateral anterior cruciate ligament reconstruction (ACLR) on maximum voluntary contraction (MVC) and explosive strength of both the involved limb and the uninvolved limb. Nineteen male athletes completed a standard isometric testing protocol 4 months post-ACLR, while 16 healthy participants served as a control group (CG). The explosive strength of the knee extensors and flexors was assessed as RFD obtained from the slope of the force–time curves over various time intervals. Both muscle groups of the involved limb had significantly lower MVC compared to the uninvolved. The involved limb also had significantly lower RFD in the late phase of contraction (140–250 ms) for both knee extensors and flexors (P < 0.05). There was no difference in MVC between the uninvolved limb and the CG. However, RFD of the uninvolved limb was lower compared to CG for both knee extensors (0–180 ms; P < 0.01) and flexors (0–150 ms; P < 0.05). ACLR leads to lower MVC and explosive strength of the involved limb. As a consequence of potential crossover (presumably neural-mediated) effects, explosive strength deficits could be bilateral, particularly in the early phase of the contraction (<100 ms).  相似文献   

7.
ABSTRACT

Knee joint coordination during jump landing in different directions is an important consideration for injury prevention. The aim of the current study was to investigate knee and hip kinematics on the non-dominant and dominant limbs during landing. A total of 19 female volleyball athletes performed single-leg jump-landing tests in four directions; forward (0°), diagonal (30° and 60°) and lateral (90°) directions. Kinematic and ground reaction force data were collected using a 10-camera Vicon system and an AMTI force plate. Knee and hip joint angles, and knee angular velocities were calculated using a lower extremity model in Visual3D. A two factor repeated measures ANOVA was performed to explore limb dominance and jump direction. Significant differences were seen between the jump directions for; angular velocity at initial contact (p < 0.001), angular velocity at peak vertical ground reaction force (p < 0.001), and knee flexion excursion (p = 0.016). Knee coordination was observed to be poorer in the early phase of velocity-angle plot during landing in lateral direction compared to forward and diagonal directions. The non-dominant limb seemed to have better coordination than the dominant limb during multi-direction jump landing. Therefore, dominant limbs appear to be at a higher injury risk than non-dominant limbs.  相似文献   

8.
Power is a fundamental component for many sporting activities; while the load that elicits peak power during different exercises and differences between sexes remains unclear. This study aims to determine the effect of sex and load on kinematic and kinetic variables during the mid-thigh clean pull. Men (n = 10) and women (n = 10) performed the mid-thigh clean pull at intensities of 40%, 60%, 80%, 100%, 120%, and 140% of one repetition maximum (1RM) power clean in a randomised and counter-balanced order, while assessing bar velocity, bar displacement, power, force, and impulse. Two-way analysis of variance revealed that men demonstrated significantly greater (p < 0.05) values for all variables across loads, excluding bar velocity. Men demonstrated significantly greater (p < 0.05) bar velocities with 40–80% 1RM; in contrast, women demonstrated significantly (p < 0.05) higher velocities with 120–140% 1RM. Irrespective of sex significantly greater (p < 0.05), system peak power, bar velocity, and displacement occurred with 40% 1RM. In contrast, peak force and impulse were significantly (p < 0.05) greater with 140% 1RM. When performing the mid-thigh clean pull, to maximise system power or bar velocity, lower loads (40–60% 1RM) are recommended. When training force production or impulse, higher loads (120–140% 1RM) are recommended, when using the mid-thigh clean pull.  相似文献   

9.
The aim of the study was to evaluate, by an electromyographic (EMG) and mechanomyographic (MMG) combined approach, whether years of specific climbing activity induced neuromuscular changes towards performances related to a functional prevalence of fast resistant or fast fatigable motor units. For this purpose, after the maximum voluntary contraction (MVC) assessment, 11 elite climbers and 10 controls performed an exhaustive handgrip isometric effort at 80% MVC. Force, EMG and MMG signals were recorded from the finger flexor muscles during contraction. Time and frequency domain analysis of EMG and MMG signals was performed. In climbers: (i) MVC was higher (762 ± 34 vs 512 ± 57 N; effect size: 1.64; confidence interval: 0.65–2.63; P < 0.05); (ii) endurance time at 80% MVC was 43% longer (34.2 ± 3.7 vs 22.3 ± 1.5 s; effect size: 1.21; confidence interval: 0.28–2.14; P < 0.05); (iii) force accuracy and stability were greater during contraction (P < 0.05); (iv) EMG and MMG parameters were higher throughout the entire isometric effort (P < 0.05). Collectively, force, EMG and MMG combined analysis revealed that several years of specific climbing activity addressed the motor control system to adopt muscle activation strategies based on the functional prevalence of fast resistant motor units.  相似文献   

10.
This study examined the validity and reliability of a 30-second running sprint test using two non-motorized treadmills compared to the established Wingate Anaerobic Test. Twenty-four participants completed three sessions in a randomized order on a: (1) manual mode treadmill (Woodway); (2) specialized interval training treadmill (HiTrainer); and (3) Wingate cycle ergometer. In a subset of 15 participants, 2 additional sessions were completed on both treadmills to establish the test–retest reliability. Peak (Woodway: r = .68; HiTrainer: r = .58; p < .003), average (Woodway: r = .82; HiTrainer: r = .72, p < .001), and minimum (Woodway: r = .64; HiTrainer: r = .42, p < .043) speed indices were moderately to very strongly correlated with corresponding Wingate Anaerobic Test outputs and had excellent test–retest reliability (all intraclass correlation coefficients > .75). Fatigue index during the Wingate Anaerobic Test (51.20 ± 7.14%) was moderately correlated with the Woodway (32.9 ± 10.9%, r = .55, p = .005) only. This 30-second running sprint test may be a valid and reliable mode-specific alternative to the Wingate Anaerobic Test.  相似文献   

11.
Abstract

This study investigated the participation and performance trends as well as the age and gender interaction at the Olympic distance ‘Zürich Triathlon’ (1.5?km swim, 40?km cycle and 10?km run) from 2000 to 2010 in 7,939 total finishers (1,666 females and 6,273 males). Female triathletes aged from 40 to 54 years significantly (P?<?0.05) increased their participation while the participation of younger females and males remained stable. Males of 50–54 years of age and females of 45–49 years of age improved their total race time. For elite top five overall triathletes, mean gender differences in swimming, cycling, running and overall race time were 15.2?±?4.6%, 13.4?±?2.3%, 17.1?±?2.5%, and 14.8?±?1.8%, respectively. For both elite and age group athletes, the gender difference in cycling time was significantly (P?<0.001) lower than for swimming and running. The gender difference in overall Olympic distance triathlon performance increased after the age of 35 years, which appeared earlier compared to long distance triathlon as suggested by previous studies. Future investigations should compare gender difference in performance for different endurance events across age to confirm a possible effect of exercise duration on gender difference with advancing age.  相似文献   

12.
Purpose: The purpose of this investigation was to examine the effects of a submaximal running warm-up on running performance in male endurance athletes (n = 16, Mage = 21 ± 2 years, MVO2max = 69.3 ± 5.1 mL/kg/min). Method: Endurance performance was determined by a 30-min distance trial after control and submaximal running warm-up conditions in a randomized crossover fashion. The warm-up began with 5 min of quiet sitting, followed by 6 min of submaximal running split into 2-min intervals at speeds corresponding to 45%, 55%, and 65% maximal oxygen consumption (VO2max). A 2-min walk at 3.2 km/hr concluded the 13-min warm-up protocol. For the control condition, participants sat quietly for 13 min. VO2 and heart rate (HR) were determined at Minutes 0, 5, and 13 of the pre-exercise protocol in each condition. Results: At the end of 13 min prior to the distance trial, mean VO2 (warm-up = 14.1 ± 2.2 mL/kg/min vs. control = 5.5 ± 1.7 mL/kg/min) and mean HR (warm-up = 105 ± 11 bpm vs. control = 67 ± 11 bpm) were statistically greater (p < .001) in the warm-up condition compared with the control condition. The distance run did not statistically differ (p = .37) between the warm-up (7.8 ± 0.5 km) and control (7.7 ± 0.6 km) conditions; however, effect size calculation revealed a small effect (d = 0.2) in favor of the warm-up condition. Thus, the warm-up employed may have important and practical implications to determine placing among high-level athletes in close races. Conclusions: These findings suggest a submaximal running warm-up may have a small but critical effect on a 30-min distance trial in competitive endurance athletes. Further, the warm-up elicited increases in physiological variables VO2 and HR prior to performance; thus, a submaximal specific warm-up should warrant consideration.  相似文献   

13.
Athletes in inner lanes may be disadvantaged during athletic sprint races containing a bend portion because of the tightness of the bend. We empirically investigated the veracity of modelled estimates of this disadvantage and the effect of running lane on selected kinematic variables. Three-dimensional video analysis was conducted on nine male athletes in lanes 8, 5 and 2 of the bend of an outdoor track (radii: 45.10, 41.41 and 37.72 m, respectively). There was over 2% (p < 0.05) reduction in mean race velocity from lane 8 (left step 9.56 ± 0.43 m/s, right step: 9.49 ± 0.41 m/s) to lane 5 (left step: 9.36 ± 0.51 m/s, right step: 9.30 ± 0.51 m/s), with only slight further reductions from lane 5 to lane 2 (left step: 9.34 ± 0.61 m/s, right step: 9.30 ± 0.63 m/s). Race velocity decreased mainly because of reductions in step frequency as radius decreased. These unique data demonstrate the extent of the disadvantage of inner lane allocation during competition may be greater than previously suspected. Variations in race velocity changes might indicate some athletes are better able to accommodate running at tighter radii than others, which should have implications for athletes’ training.  相似文献   

14.
The purpose of this study was to compare the lower extremity inter-joint coordination of different collision forces runners during running braking phase. A dynamical system approach was used to analyse the inter-joint coordination parameters. Data were collected with six infra-red cameras and two force plates. According to the impact peak of the vertical ground reaction force, twenty habitually rearfoot-strike runners were categorised into three groups: high collision forces runners (HF group, n = 8), medium collision forces runners (MF group, n = 5), and low collision forces runners (LF group, n = 7). There were no significant differences among the three groups in the ankle and knee joint angle upon landing and in the running velocity (p > 0.05). The HF group produced significantly smaller deviation phase (DP) of the hip flexion/extension-knee flexion/extension during the braking phase compared with the MF and LF groups (p < 0.05). The DP of the hip flexion/extension-knee flexion/extension during the braking phase correlated negatively with the collision force (p < 0.05). The disparities regarding the flexibility of lower extremity inter-joint coordination were found in high collision forces runners. The efforts of the inter-joint coordination and the risk of running injuries need to be clarified further.  相似文献   

15.
Abstract

The aim of this study was to objectively quantify ratings of perceived enjoyment using the Physical Activity Enjoyment Scale following high-intensity interval running versus moderate-intensity continuous running. Eight recreationally active men performed two running protocols consisting of high-intensity interval running (6×3 min at 90% [Vdot]O2max interspersed with 6×3 min active recovery at 50% [Vdot]O2max with a 7-min warm-up and cool down at 70% [Vdot]O2max) or 50 min moderate-intensity continuous running at 70% [Vdot]O2max. Ratings of perceived enjoyment after exercise were higher (P < 0.05) following interval running compared with continuous running (88 ± 6 vs. 61 ± 12) despite higher (P < 0.05) ratings of perceived exertion (14 ± 1 vs. 13 ± 1). There was no difference (P < 0.05) in average heart rate (88 ± 3 vs. 87 ± 3% maximum heart rate), average [Vdot]O2 (71 ± 6 vs. 73 ± 4%[Vdot]O2max), total [Vdot]O2 (162 ± 16 vs. 166 ± 27 L) or energy expenditure (811 ± 83 vs. 832 ± 136 kcal) between protocols. The greater enjoyment associated with high-intensity interval running may be relevant for improving exercise adherence, since running is a low-cost exercise intervention requiring no exercise equipment and similar relative exercise intensities have previously induced health benefits in patient populations.  相似文献   

16.
Recently, addition of a gymnastics glide kip to a standard pull-up (SPU) has resulted in the kipping pull-up (KPU). Changes in muscle activation and kinematics were evaluated with eleven athletes performing sets of 5 SPU and 5 KPU. Surface electromyography of upper body and lower body muscles was recorded along with movement kinematics obtained via markers and motion tracking software. Most kinematic variables were significantly higher in the KPU including (KPU minus SPU deg): Max hip angle (48.8° ± 6.8°, p < 0.001) and max knee angle (56.5° ± 11.3°, p < 0.001). The recruitment of core and lower body muscles was significantly higher in the KPU (% MVIC increase): rectus abdominis (28.7 ± 4.7%, p < 0.001), external oblique (21.8 ± 4.1%, p < 0.001), iliopsoas (26.1 ± 5.5%, p = 0.001) and tensor fasciae latae (13.5 ± 2.3%, p < 0.001). Correspondingly, the biceps brachii had lower activation in the KPU (% MVIC decrease): (26.7 ± 0.6%, p = 0.006). Depending on the athlete’s goal, they may elect to perform an SPU for higher upper body muscle activation; or the KPU for more full-body activation with the potential to perform more repetitions through reduced upper body fatigue.  相似文献   

17.
Countermovement jump (CMJ) height is an important parameter in physical performance. This study compared CMJ height measured using ChronoJump contact mat (CJ) and Myotest accelerometer (MT) systems with a force platform (FP). Thirty recreationally active adults (32.1 ± 10.4 years, 75.9 ± 12.0 kg, 173.2 ± 6.3 cm) completed a CMJ protocol where height was simultaneously recorded using the three systems. CJ and MT measures were strongly and significant correlated (r = 0.65, 0.66, respectively; p < 0.05) with FP. CJ-derived measures were not significantly different to FP measures (p > 0.05), yet MT-derived measures were significantly different from those obtained using the FP (p < 0.05). Systematic bias was observed between FP and the CJ and between FP and MT. This study demonstrates the validity of CJ and MT systems for the assessment of CMJ height. Systematic bias and between-device differences in measurement should be considered when interpreting and comparing data from these devices.  相似文献   

18.
The purpose of this study was to evaluate the effects of cold-water immersion on the electromyographic (EMG) response of the lower limb and balance during unipodal jump landing. The evaluation comprised 40 individuals (20 basketball players and 20 non-athletes). The EMG response in the lateral gastrocnemius, tibialis anterior, fibular longus, rectus femoris, hamstring and gluteus medius; amplitude and mean speed of the centre of pressure, flight time and ground reaction force (GRF) were analysed. All volunteers remained for 20 min with their ankle immersed in cold-water, and were re-evaluated immediately post and after 10, 20 and 30 min of reheating. The Shapiro–Wilk test, Friedman test and Dunn’s post test (P < 0.05) were used. The EMG response values decreased for the lateral gastrocnemius, tibialis anterior, fibular longus and rectus femoris of both athletes and non-athletes (P < 0.05). The comparison between the groups showed that the EMG response was lower for the athletes. Lower jump flight time and GRF, greater amplitude and mean speed of centre of pressure were predominant in the athletes. Cold-water immersion decreased the EMG activity of the lower limb, flight time and GRF and increased the amplitude and mean speed of centre of pressure.  相似文献   

19.
ABSTRACT

The objective of this study was to analyse the effect of the use of social networks in smartphones or playing video games on the passing decision-making performance in professional soccer athletes. Participants were 25 male professional soccer athletes (mean ± SD: age 23.4 ± 2.8 years). The participants performed three randomised conditions divided into three groups: control (CON), smartphone (SMA), and video game (VID). Before and after each experimental condition, the Stroop Task assessed the level of induced mental fatigue. Then, the athletes performed a simulated soccer match. A CANON® camera recorded the matches for further analysis on passing decision-making performance. A group effect was identified (p < .01) with impairment on passing decision-making performance for the SMA (p = .01, ES = 0.5) and VID (p = .01, ES = 0.5) conditions. We concluded that the use of social networks on smartphones and/or playing video games right before official soccer matches might impair the passing decision-making performance in professional soccer athletes.  相似文献   

20.
Abstract

The study empirically tested the postulate of the Developmental Model of Sport Participation (DMSP; Côté, J., Baker, J., & Abernethy, B. (2007). Practice and play in the development of sport expertise. In R. Eklund & G. Tenenbaum (Eds.), Handbook of sport psychology (pp. 184–202). Hoboken, NJ: Wiley) that diversified childhood self-led sport play will beneficially affect future, adolescent intrinsic motivation. Participants were 178 elite youth athletes (age 15.3?±?1.5 years) from several game and non-game sports; 117 were members of the federal state or national junior squad in their respective sport. A questionnaire measured current (adolescent) intrinsic and extrinsic motivation of the youth athletes using the Sport Motivation Scale (Pelletier, L. G., Fortier, M. S., Vallerand, R. J., Tuson, K. M., Brière, N. M., & Blais, M. R. (1995). Towards a new measure of intrinsic motivation, extrinsic motivation, and amotivation in sports: The sport motivation scale (SMS). Journal of Sport & Exercise Psychology, 17, 35–53) and their earlier volume of childhood engagement (through 12 years) in coach-led practice and self-led play in their respective main sport and other sports. Analyses revealed that adolescent intrinsic motivation was not significantly correlated with earlier childhood self-led sport activities, self-led play in particular, or childhood sports diversification. Furthermore, considering all different types of childhood sport activities together in multiple regression analyses, they did not provide meaningful explanatory power regarding adolescent intrinsic or extrinsic motivation. In summary, the results did not provide support for the postulate of the DMSP among elite youth athletes. The findings suggest that future research may seek to enable more robust empirical substantiation of the DMSP postulate.  相似文献   

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