Jumping Exercise Research Articles

Force-Velocity Relationship in the Countermovement Jump Exercise Assessed by Different Measurement Methods

This study aimed to compare force, velocity, and power output collected under different loads, as well as the force-velocity (F-V) relationship between three measurement methods. Thirteen male judokas were tested under four loading conditions (20, 40, 60, and 80 kg) in the countermovement jump (CMJ) exercise, while mechanical output data were collected by three measurement methods: the Samozino's method (SAM), a force platform (FP), and a linear velocity transducer (LVT). The variables of the linear F-V relationship (maximum force [F0], maximum velocity [V0], F-V slope, and maximum power [P0]) were determined. The results revealed that (1) the LVT overestimated the mechanical output as compared to the SAM and FP methods, especially under light loading conditions, (2) the SAM provided the lowest magnitude for all mechanical output, (3) the F-V relationships were highly linear either for the SAM (r = 0.99), FP (r = 0.97), and LVT (r = 0.96) methods, (4) the F-V slope obtained by the LVT differed with respect to the other methods due to a larger V0 (5.28 ± 1.48 m·s-1) compared to the SAM (2.98 ± 0.64 m·s-1) and FP (3.06 ± 0.42 m·s-1), and (5) the methods were significantly correlated for F0 and P0, but not for V0 or F-V slope. These results only support the accuracy of the SAM and FP to determine the F-V relationship during the CMJ exercise. The very large correlations of the SAM and LVT methods with respect to the FP (presumed gold-standard) for the mean values of force, velocity and power support their concurrent validity for the assessment of mechanical output under individual loads.

Squat Jump Exercise Increased Spike Jump and Block Jump Reach of Junior Volleyball Athletes

Spike jump and block jump were characteristic movements of volleyball. These movement were determined by explosive power of leg, strength of musculoskeletal, length of lower limb and length of arm. Explosive power could be enhanced by plyometric exercise, like squat jump. The aims of study to analyse the role of squat jump exercise program on spike jump reach and block jump reach of junior volleyball athletes. Twenty-three junior athletes (male 11 and female 12) participated in pre and post-test experiment study. The squat jump exercise program was conducted three time a week, for along 7 weeks. The squat jump exercise involved squat jump, squat jumpwithbox,forearmpassingwhilesquatjumpandsquatjumpwithrunningtakeoff. The data were analysed by paired t-test to compare pre and post-test. The experiment resultedincreasingofspikejumpbothmen(p<0.001)andwomen(p<0.001).Increasing of block jump in men (p<0.001) and women (p=009). We concluded that squat jump exercise regularly effective to increase the spike jump and block jump reach junior volleyball athletes.

Pengaruh Latihan Side-To-Side Shuffle Jump terhadap Peningkatan Daya Ledak Otot Tungkai

The purpose of this study was to determine the effect of side-to-side jump training on increasing leg muscle explosive power. This research was an experimental research. The sampling technique used in the research was purposive sampling with 17 samples that were given an early test of vertical jump (modified sargent jump) and followed by the treatment of 14 sessions. The latest test was the post test to see the effect of the exercise. T-test was used to see the effect of the significant mean α 0,05. The results of the posttest mean was 98.26 and preetest mean was100.45. The hypothesis research was accepted because the result of ttest (6.22)>ttable (2.11). Conclusion, Side-to-Side Shuffle Jump exercises affect the increase of explosive limb muscle strength of Bung Hatta University Physical, Health and Recreation Education
 Keywords: Side-to-Side Shuffle Jump, Leg Muscles Explosive Power

High Intensity Jump Exercise Preserves Posture Control, Gait, and Functional Mobility During 60 Days of Bed-Rest: An RCT Including 90 Days of Follow-Up.

Physical inactivity causes a deconditioning of the human body. Concerns due to chronic bed-rest include deficits in posture and gait control, predisposing individuals to an increased fall and injury risk. This study assessed the efficiency of a high-load jump exercise (JUMP) as a countermeasure to prevent detrimental effects on gait, posture control and functional mobility. In an RCT (23 males), the effect of 60 days bed-rest without training was compared to JUMP. JUMP is characterized by plyometric executed as a high intensity interval training. Typical trainings session consisted of 4 × 10 countermovement jumps and 2 × 10 hops in a sledge jump system. We assessed sway path and muscle activity in monopedal stance, spatiotemporal, kinematic, and variability characteristics in gait, functional mobility with repeated chair-rises and Timed Up and Go (TUG). Results revealed: The JUMP group showed no significant changes after bed-rest, whereas the control group exhibited substantial deteriorations: an increased sway path (+104%, p < 0.05) was accompanied by increased co-contractions of antagonistic muscles encompassing the ankle (+32%, p < 0.05) and knee joint (45%, p < 0.05). A reduced locomotor speed (−22%, p < 0.05) was found concomitant with pathological gait rhythmicity (p < 0.05), reduced joint excursions (ankle −8%, knee −29%, p < 0.05) and an increased gait variability (p < 0.05). Chair-rising was slowed (+28%, p < 0.05) with reduced peak power (+18%, p < 0.05), and more time was needed to accomplish TUG (+39%, p < 0.05). The effects persisted for a period of 1 month after bed-rest. Increases in sway path were correlated to decreases in gait speed. The JUMP effectively preserved the neuromuscular system's ability to safely control postural equilibrium and perform complex locomotor movements, including fast bipedal gait with turns and rises. We therefore recommend JUMP as an appropriate strategy combatting functional deconditioning.

Feasibility and safety of a 6-month exercise program to increase bone and muscle strength in children with juvenile idiopathic arthritis

BackgroundArthritis in childhood can be associated with muscle weakness around affected joints, low bone mass and low bone strength. Exercise is recognized as an important part of management of children with juvenile idiopathic arthritis (JIA) but the exercise prescription to best promote bone and muscle health is unknown. We therefore aimed to: 1. assess feasibility and safety of a 6-month home- and group-based exercise program for children with JIA; 2. estimate the effect of program participation on bone mass and strength, muscle function and clinical outcomes and 3. determine if any positive changes in bone and muscle outcomes are maintained 6 months later.MethodsWe recruited 24 children with JIA who were part of the Linking Exercise, Physical Activity and Pathophysiology in Childhood Arthritis (LEAP) study to participate in a 6-month home-based exercise program involving jumping and handgrip exercises, resistance training and one group exercise session per month. We assessed lumbar spine bone mass (dual energy X-ray absorptiometry), distal tibia and radius bone microarchitecture and strength (high-resolution peripheral quantitative computed tomography), muscle function (jumping mechanography, dynamometry) and clinical outcomes (joint assessment, function, health-related quality of life) at baseline, 6- and 12-months. Adherence was assessed using weekly activity logs.ResultsThirteen children completed the 6-month intervention. Participants reported 9 adverse events and post-exercise pain was rare (0.4%). Fatigue improved, but there were no other sustained improvements in muscle, bone or clinical outcomes. Adherence to the exercise program was low (47%) and decreased over time.ConclusionChildren with JIA safely participated in a home-based exercise program designed to enhance muscle and bone strength. Fatigue improved, which may in turn facilitate physical activity participation. Prescribed exercise posed adherence challenges and efforts are needed to address facilitators and barriers to participation in and adherence to exercise programs among children with JIA.Trial registrationData of the children with JIA are from the LEAP study (Canadian Institutes of Health Research (CIHR; GRANT# 107535). http://www.leapjia.com/

Comparison Between Stainless Steel and Titanium Snaffle Bits in Sport Horses During Show Jumping Exercise

Snaffle bits are usually made of stainless steel, but innovative materials have been investigated to reduce horses’ discomfort and mouth injuries. Being light and biocompatible, titanium could improve horse well-being. This study aimed at comparing stainless steel (S) versus titanium (T) snaffle bits in show jumping horses. Eighteen rider-horse pairs were randomly assigned in a blinded manner to wear an S or T bit over 2 consecutive days in different sequences (ST or TS) after a 2 × 2 crossover design. Horses were homogeneous for age, training, and mouth conditions. The treatment effect (S vs. T) was analyzed by a generalized linear mixed model for paired data considering: the temperature of muzzle and neck before and after training measured via infrared thermography; the temperature of the snaffle bit and horse salivary pH after exercise; and the answers of a survey consisting in six multiple-choice questions on bit acceptance taken by the rider after exercise. The T bit showed a minor increase in muscle temperature during exercise than the traditional S bit, showed after training by a lower (P < .05) temperature increase at muzzle (0.63 vs. 1.39°C for T and S) and neck (1.96 vs. 2.70°C for T and S) and a lower temperature of the snaffle bit (30.23 vs. 32.10°C for T and S). All the temperatures were within a physiological range. No differences due to the snaffle bit were observed for salivary pH and survey, apart from a slightly greater but not significant acceptance for T than for S snaffle bit.

Pengaruh Latihan Lompat Kardus Terhadap Hasil Lompat Jauh Gaya Jongkok Pada Siswa SD Negeri 132 Palembang

This study aims to determine how big the influence of cardboard jump exercise on the long jump style of squatting on students of State Elementary School 132 Pelembang. This type of research is experiment. Where the sample of students of State Elementary School 132 which amounted to 30 male students divided into 2 groups by ordinal pairing, ie 15 people experimental group given the treatment of cardboard jumping exercise and 15 people who were not given treatment. To determine the sample size can be calculated at least 20 - 25% of the existing popu- lation. To determine the sample by using random sampling technique and to divide the treatment and control group by ordinal pairing based on the pre test result after the research, it is concluded that there is the effect of cardboard jump exercise on the long jump style of squatting on the students of Elementary School 132 Palembang. In this cardboard jump exercise is a leaping motion that uses one leg and lands on two legs with the aim of obtaining a leap that far away. Data collection techniques used initial and final test techniques. The statistics used to analyze the data in the study using t test. The result of t test shows that ttable test = 1.70 whereas tcount = 3,49, dk = 28 and = 5%, so. Thus reject Ho and accept Ha which states there is the effect of cardboard jump exercise on the long jump style of squatting on students of Elementary School 132 Palembang.

Comparative Effect of Squat Jump and Split Jump Exercise on Dynamic Balance among Female Netball Players

Background: Dynamic balance is an ability to move two or more body parts under control. The split and squat jump exercise primarily strengthen gluteus, hamstring muscles, quadriceps, and calves muscles, as well as provide cardiovascular benefits. The objectives of the study were to find the effect of split jump and squat jump exercise on dynamic balance and to compare the effect of exercise on the dynamic balance among female netball players in KPJ University College. Methods: An experimental design with total 80 female subjects were selected and divided equally to 40 subjects in each group. The Star Excursion Balance Test was used to measure the outcome of dynamic balance before and after the intervention. Group A received split jump exercise whereas Group B received squat jump exercise. The intervention was given for six weeks with three sessions for each week. After six weeks of intervention, the researcher checked dynamic balance for both groups. Results: The result showed that there is a significant difference between the groups with P-values 0.0043, 0.0001, 0.0471,0.0001 for anterior, lateral, posterior and medial respectively. Conclusion: The study concluded that both exercises could improve dynamic balance. However, the squat jump exercise is more effective to improve dynamic balance among netball players.

Investigating the Relationship between Sprint and Jump Performances with Velocity and Power Parameters during Propulsive Phase of the Loaded-squat Jump Exercise

The purpose of this study was to investigate the relationship between sprint and jump performance with velocity parameters in the loaded-squat jump exercise (SQLoaded). In accordance with this purpose, a total of 13 athletes competing in martial sports have participated in this study voluntarily. In this study, sprint tests, vertical jump (VJ), standing long jump (SLJ) tests and one repetition maximal strength test were applied. In order to determine velocity and power parameters, SQLoaded exercise was applied by using an external load that corresponds to 40% of body weights of the subjects via an isoinertial velocity transducer (T-Force dynamic measurement system) and values of mean propulsive velocity (MPV), peak velocity (PV), mean propulsive power (MPP) and peak power (PP) were obtained. Descriptive statistics, Spearman correlation analysis and Shapiro-Wilk normality tests were used for data assessment. It has been concluded that there is no statistically significant relation between 10, 20 and 30 meter sprint times and the values of MPV (r= -,332; r= -,375; r= -,446; p>.05 respectively), PV (r= -,058; r= -,118; r= -,165; p>.05 respectively), MPP (r= -,285; r= -,482; r= -,485; p>.05 respectively) and PP (r= -,205; r= -,512; r= -,391; p>.05 respectively) during SQLoaded exercise. In addition, while no statistically significant relation has been obtained between the VJ and SLJ values of the participants and MPV (r= ,496; r = ,429; p>.05 respectively) and PV (r= ,300; r= ,223; p>.05 respectively) values during propulsive stage of SQLoaded exercise, it has been ascertained that there is a statistically positive and significant relation between the values of MPP(r= ,620; r= ,580; p>.05 respectively) and PP (r= ,678; r=,572; p<.05 respectively). In conclusion, it can be suggested that lifting velocity and power values don't have a positive effect on short sprint performance; however power values affect the vertical jump and standing long jump performances positively.

Comparison of the Velocity and Power Parameters During Loaded-Squat Jump Exercise of National Athletes in Different Branches

The aim of this investigation is to compare velocity and power variables during loaded-squat jump (SJLoaded) exercise of national athletes dealing with different sports branches and to identify whether velocity and power parameters become different or not according to branches. In accordance with this purpose, a total of 36 national athletes (age: 20.3±1.68 years; height: 173.5±6.46 cm; weight: 72.3±10.29 kg) composed of 12 wrestlers (age: 19.5±.90 years; height: 172.3±6.19 cm; weight: 75.5±13.9 kg), 12 arm wrestlers (age: 20.5±2.02 years; height: 174.7±4.76 cm; weight: 72.6±8.31 kg) and 12 kickboxers (age: 20.7±1.81 years; height: 173.5±8.29 cm; weight: 68.9±6.94 kg) dealing with different sports branches have voluntarily participated in this study. For identifying velocity and power parameters, SJLoaded exercise was executed with an external load that corresponds to 40% of body weights of the athletes by utilizing an isoinertial velocity transducer (T-Force dynamic measurement system) and values of mean velocity (MV), mean propulsive velocity (MPV), peak velocity (PV), mean power (MP), mean propulsive power (MPP) and peak power (PP) were determined. All data analyzes were performed in the SPSS 16.0 statistical program. Firstly, in order to analyze data, it was determined that the data indicated normal distribution by looking at the Shapiro-Wilk coefficient regarding the normality of the distribution of the data. Therefore one-way analysis of variance (One-way ANOVA) was utilized to identify statistical significant differences among athletes competing in different branches with regard to the velocity and power variables during the SJLoaded exercise. According to analyze results, no statistical significant difference wasn’t seen among branches with regard to MV [f (2.33) = 1.306], MPV [f (2. 33)=2.195], PV [f (2. 33)=2.242], MP [f (2. 33)=1.225], MPP [f (2. 33)=2.787] and PP [f (2. 33)= 2.607] parameters during SJLoaded exercise (p&gt;0.05). The velocity and power parameters obtained in the SJLoaded exercise don’t differ according to the branches.

The Relationship between Repeated Sprint Performance and Velocity Values during Loaded-Squat Jump Exercise

The purpose of this study is to investigate the relationship between repeated sprint performance and velocity values during loaded-squat jump exercise. In accordance with this purpose, 23 kickboxing athletes (age: 21,1 ± 2,10 years; height: 178,7±5,01 cm; weight: 70,8±7,85 kg) participated voluntarily in this study. Participants were performed to repeated sprint test and loaded-squat jump exercise by using an external load corresponding to 40 % of their body weight and velocity parameters were obtained as mean velocity (MV), mean propulsive velocity (MPV) and peak velocity (PV). Descriptive statistics were used in analysis of data. In addition, Spearman Correlation Analysis was used to determine the relationship between repeated sprint performance and velocity values during loaded-squat jump exercise. According to the analysis results; while total running times and fatigue index values in repeated sprint test of subjects were obtained as 52.4 (±1.96 sec) and 4.98 (±2.36%) respectively; velocity values during loaded-squat jump exercise were obtained as 1.38 (±,07 m/s-1) for MP, 1.54 (±,10 m/s-1) for MPV, and 2.58 (±,15 m/s-1) for PV. In addition, it was determined that there was no any statistically significant difference between MP (r= - ,148; r= - ,072, p&gt;0.05, respectively), MPV (r= - ,335; r= - ,150, p&gt;0.05, respectively), PV (r= ,010; r= - ,034, p&gt;0.05 respectively) and total running time and fatigue index values in repeated sprint test. As a result, it can be suggested that velocity values during loaded squat jump exercise have no statistically significant effect on repeated sprint performance.

Comparison of Power, Velocity and Force Parameters during Loaded Squat Jump Exercise in the Handball and Arm Wrestling Players

The purpose of this study was to compare power, velocity and force parameters during loaded squat jump (SJ) exercise in the handball and arm wrestling players. In accordance with this purpose, ten arm wrestling athletes from the Turkish National Team (age: 20,7 ± 3,05 years; height: 175,2 ± 5,55 cm; weight: 71,7 ± 8,17 kg) who had ranks in competitions at World and Europe Am Wrestling Championships and ten handball players (age: 23,0 ± 4,00 years; height: 182,3 ± 6,06 cm; weight: 77,8 ± 11,3 kg) who competed at Turkish handball 1st league participated voluntarily in this study. Subjects were performed loaded SJ exercise using a load equals to 40 % of their body weight and obtained the power, velocity and force values using an isoinertial measurement system (T-Force Dynamic Measurement System). For data analysis, descriptive statistic and Mann Whitney - U analyses were used. According to analysis results, there was a statistically significant difference between jump velocity during loaded SJ of handball players and arm wrestling athletes (p &lt; 0.05). Accordingly, arm wrestling athletes have better jump velocity than handball players in terms of mean velocity (MV) and peak velocity (PV). In addition, it was obtained that there wasn’t a statistically significant difference between handball and arm wrestling players in terms of mean force (MF), mean propulsive force (MPF), peak force (PF), peak power (PP), mean propulsive power (MPP), mean power (MP), time and moving distance to barbell bar during loaded SJ (p &gt; 0.05). Consequently, jump ability is a crucial performance indicator in many sports that require explosive actions and the lower-body muscular power. However, it is not a true approach that athletes competing at sport branches which jump ability is an important performance indicator can display a better performance during loaded SJ.

The effects of exercise load during development on oxidative stress levels and antioxidant potential in adulthood

The objective of this study was to elucidate the impact of physical activity during the growth period as well as on oxidative stress and antioxidative potential in adulthood. The experimental animals used were four-week old male Wistar rats, which were randomly divided into three groups. The exercise loads were as follows: control (CON), treadmill exercise (TE), and jumping exercise (JE). The exercise was performed at the same time of day, at a frequency of five days per week, for eight weeks. Derivatives of reactive oxygen metabolites (d-ROSs) and biological antioxidant potential (BAP) were measured during periods of rest prior to commencement of the experiment and after the experiment. Analysis was conducted using a Wilcoxon signed-rank test and Schaffer’s multiple comparison procedure and the significance level was set at p < 0.05. The percent increase in d-ROM levels in the JE group, which experienced short-duration intense exercise loads, was higher than that in the TE group, which experienced moderately intense exercise loads. However, BAP, which is an index of antioxidant potential, markedly decreased in adulthood in the CON group, as compared to that in the developmental period, whereas the exercise groups showed no notable changes in BAP levels. Oxidative stress levels and antioxidant potential are affected differently in adulthood, depending on the intensity of sustained exercise loads experienced during development. Results suggested that in order to increase antioxidant potential, while taking oxidative stress production into account, moderately intense exercise loads are more desirable than highly intense exercise loads.

Effect of Immersion on Ground Reaction Force and Contact Time During Drop Jump Exercise.

Dell'Antonio, E, Ruschel, C, de Brito Fontana, H, Haupenthal, A, Pereira, SM, and Roesler, H. Effect of immersion on ground reaction force and contact time during drop jump exercise. J Strength Cond Res 30(12): 3443-3449, 2016-This study analyzed the effect of water immersion on vertical ground reaction force (GRF) peaks and contact times during the braking, propulsion, and landing phases of drop jumps (DJs). Twenty-five healthy male athletes of volleyball and track and field (age 18.0 ± 2.4 years) participated in this study. Peak vertical GRF during braking, propulsion, and landing phases; time duration of braking and propulsion phases; and total contact time were measured during maximum DJs performed on land and in water at 4 levels of immersion (tibia, knee, thigh, and hip). A force plate was used to collect GRF data, and the braking and propulsion phases of contact were determined by using an electrical goniometer placed on subject's knee. The effect of immersion level on variables was analyzed through the use of a repeated measures analysis of variance (p ≤ 0.05). The results showed that increasing immersion leads to a decrease in peak force during the braking phase, landing phase, and in the propulsion phase of the DJ, with the decrease in peak forces between immersions being greater as the immersion level gets deeper. Concerning the contact times, increasing immersion levels caused an increase in total contact time and in the duration of the braking phase. No differences were found for the duration of the propulsion phase between the conditions. Our results have shown that temporal features of the DJ were not preserved in water, and this must be taken into account when choosing the aquatic environment as an alternative for plyometric training. If the rationale of performing plyometric training in water is the reduction of GRFs, then hip immersion seems to offer an interesting combination of significantly lower GRF but without further modification of important temporal features when compared with the other water conditions analyzed.

The morphological and functional effects of exercise in the aquatic environment, performed before and/or after sciatic nerve compression in Wistar rats.

The aim of this study was to evaluate the effects of exercise in the aquatic environment, performed before and/or after sciatic nerve compression in Wistar rats on morphological and functional parameters. Twenty-five Wistar rats were divided into the following groups: control (C), lesion (L), trained+lesion (TL), lesion+exercise (LE), and training+lesion+exercise (TLE), who underwent right sciatic nerve compression on day 21 of the experiment. The TL and TLE groups were submitted to a jumping exercise in a water environment for 20 days prior to injury and the LE and TLE groups after injury. The functional analysis was carried out using the sciatic functional index (SFI). On the last day of the experiment, the right sciatic nerves were collected, processed and analysed according to morphology and morphometry. The C group showed higher SFI in relation to the other groups. In the morphometric analysis, in comparison to C, all groups showed a decrease in the diameter of the injured nerve fibre, the myelin sheath and an increase in the percentage of connective tissue. There was a decrease in axon diameter in L, TL, and LE groups and a decrease in the density of nerve fibres in the TL and LE groups. The exercise did not affect functional recovery. However, the exercise prior to the injury improved morphology of the nervous tissue, and when performed pre- and postinjury, there was also an improvement in nerve regeneration, but this was not the case with exercise performed after the injury demonstrating worse results.

The Effects Of Traditional Chinese Massage On Muscle Damage Status And Blood Leukocyte Subpopulations After An Acute Repeated Jump Exercise

PURPOSE: Traditional Chinese massage has been used to treat muscle soreness and tightness for centuries in oriental countries. Therefore, the purpose of the present study was to investigate the effect of traditional Chinese massage on muscle damage and the changes of blood leukocyte subpopulation after an acute bout of repeated deep-squat jump exercise. METHODS: Traditional Chinese massage has been used to treat muscle soreness and tightness for centuries in oriental countries. Therefore, the purpose of the present study was to investigate the effect of traditional Chinese massage on muscle damage and the changes of blood leukocyte subpopulation after an acute bout of repeated deep-squat jump exercise. RESULTS: An acute jumping exercise significantly increased blood creatine kinase at 24- and 48-hours after exercise in both groups (p<.05), whereas there were no difference between two groups. Total white blood cell (WBC) numbers significantly increased at 24- and 48-hours after acute jumping exercise (p<.05), but the magnitude of WBC increase was lower in CMSG (p<.05). The level of neutrophil (Neu) significantly increased but lymphocyte (Lym) markedly decreased at 24-hours after this muscle-damaging exercise (p<.05). However, no difference in leukocyte subpopulation were observed between two groups. CONCLUSIONS: The CMSG has no effects on attenuating muscle damage status after an acute muscle jumping exercise. Although CMSG suppressed an increase in total WBC after exercise in compared with AR, there were no effects of CMSG on the changes of leukocyte subpopulation in response to acute muscle damaging exercise.

MHC Isoforms Are Associated with Acute Neuromuscular Performance Changes Induced by Prolonged Jumping Exercise

Prolonged fatiguing exercise has been demonstrated to cause ultrastructural changes in skeletal muscle and its metabolism that may further cause decreases in neuromuscular performance. PURPOSE: To investigate changes in maximal performance and muscle activity (EMG) and their associations with myosin heavy chain isoforms (MHC). METHODS: Ten young men (age 26±6 yrs; height 180±8 cm; body mass 77.8±11.2 kg) volunteered to participate. Prolonged unilateral jumping exercises were performed on a sledge apparatus (jump time varied from 3:20-30:12 min, and number of jumps from 61-1248). Measurements for isometric maximal voluntary contraction (MVC), maximal drop jumps (MDJ), blood analyses, and muscle biopsies were obtained at pre, immediately post, 3 and 20 hours post jumping exercises. The pre muscle biopsy was taken from the control (left) leg ~3 hours prior to the fatiguing exercise, and subsequent biopsies from the exercised (right) leg immediately and 3 hours post exercise. RESULTS: The vastus lateralis muscle contained MHC isoforms analyzed from the pre-samples as follows: I 41.2±8.8%, IIA 35.4±7.5% and IIX 22.4±5.7%. After the fatiguing exercise, the mean (±SD) peak blood lactate concentrations were 7.8±3.3 mmol/l and creatine kinase activity 1043±442 U/l. MVC decreased by 43.7±15.8% (from 2505±1070 to 1343±511 N) from pre to immediately post, with a simultaneous 14.9±25.5% increase in EMG of the vastus medialis muscle. Rate of force development decreased by 24.6±31.0%, and take-off velocity in MDJ by 18.1±8.6% in the fatigued leg. MHCI was associated with relative changes in MVC (r=-0.73, p<0.01) and EMG (r=-0.71, p<0.01), and the changes in MVC and EMG were correlated (r=0.65, p<0.05). No respective changes and associations were noticed in the control leg. CONCLUSIONS: The fatiguing stretch-shortening cycle exercises induced muscle damage and large reductions in neuromuscular performance that were associated with respective changes in EMG of the activated muscles. MHCs were associated with decrements in performance: lower MHCI had more substantial reductions in performance. Maximal neuromuscular performance acutely decreases mainly due to impaired functions of fatigued type II fibers.

Efeitos da prática de Jump no equilíbrio e no tempo de reação em mulheres

Introdução: A prática de Jump em academias vem ganhando destaque, principalmente em mulheres. Objetivo: Verificar os efeitos da prática de Jump no equilíbrio e no tempo de reação de mulheres. Métodos: Fizeram parte do estudo 12 mulheres com média de idade 22,9 ± 3,31 anos. As participantes foram submetidas a 16 sessões de Jump, com duração de 60 minutos, cada. As sessões de prática apresentaram exercícios variados, contendo movimentos de giros, mudança de direção e passos com apoio unipodal e bipodal, coreografados. Resultados: Foram encontradas diferenças estatisticamente significativas para o tempo de reação simples (t= 6,36; p= 0,000). Esses dados indicam que a prática sistemática de Jump, é benéfica para a diminuição do tempo de reação simples de mulheres. Conclusão: Apesar da não verificação de diferenças estatísticas, o TRE e o equilíbrio mostraram ser capacidades importantes para uma vida mais ativa fisicamente.

Effect of rope jumping exercise on foot arch in boy students with cavus, planus, and normal foot types

Introduction : The plantar arch is an architectural structure consisted of several joints, ligaments and muscles. It builds a functional unit that plays a vital role in weight bearing activities such as rope jumping. In this study, the effects of 12 weeks rope jumping on plantar arch in boy students with low, moderate, and high foot arches were evaluated. Materials and Methods: It was a controlled experimental study. At the beginning of study, the plantar arches of 450 boys (aged 10 to 13 years) were evaluated by Staheli index. Accordingly, 30 participants were recruited from every group with low, moderate, and high foot arches, provided their parents signed the informed consent form. Then, subjects of each study group were randomly assigned into control and experimental groups (n=15). Experimental groups took part in a 45- minute rope jumping program of 3 sessions per week, lasting for 12 weeks. Data were statistically analyzed by the use of Mixed ANOVA, using SPSS 22 software. Results: Compared to pre-test, post-test scores of plantar arch showed no difference in any control groups, nor in moderate-arch and high-arch experimental groups, but it showed significant increase in low-arch experimental group (p<0.01). Conclusion Our findings demonstrated that rope jumping exercises could improve plantar arch in boy students 10-13 years old with flexible flat foot. Therefore, we recommend such exercises to boy adolescents and call for the same study on girl adolescents. Keyword : rope jumping exercise, plantar arch, student, flat foot (pes planus), pes cavus.

Effect of Plyometric Jumps on Hemodynamic Response in Quadriceps Muscle after Exercise

Acute exercise is able to changes muscle blood flow rapidly, which may affect muscle tissue repair process during post-exercise recovery. The purpose of this study was to determine the effect of plyometric jumps on postexercise maximal oxygen consumption and hemodynamic response in the quadriceps muscle of female basketball players. Ten women's college basketball players participated in this cross-over study. Participants in respective trials performed both plyometric depth jumps (PDJ) and double-leg tuck jumps (DLTJ) exercise. Each trial was separated with at least one week interval. Maximal oxygen consumption and changes in hemodynamics data of quadriceps were collected before and 4 hours after the jump exercise. We found that the PDJ trial had significantly greater total hemoglobin (PDJ: 27.0 ± 3.5 μM vs. DLTJ: 20.6 ± 2.4 μM), oxygenated hemoglobin (PDJ: 18.0 ± 2.6 μM vs. DLTJ: 13.0 ± 1.6 μM) and deoxygenated hemoglobin (PDJ: 9.1 ± 1.1 μM vs. DLTJ: 7.7 ± 0.8 μM) levels compared to DLTJ trial after 4 hour recovery. Moreover, the maximal oxygen consumption was significantly higher in PDJ trial than DLTJ trial (PDJ: 34.5 ± 1.4 ml/kg/min vs. DLTJ: 32.6 ± 1.5 ml/kg/min). This study concludes that players in PDJ trial showed a greater maximal oxygen consumption than players in DLTJ trial after 4 hour recovery. This improvement might be due to a greater effect of PDJ exercise on enhancing muscle blood flow during post-exercise recovery.