Power output and work in different muscle groups during ergometer cycling

The aim of this study was to calculate the magnitude of the instantaneous muscular power output at the hip, knee and ankle joints during ergometer cycling. Six healthy subjects pedalled a weight-braked bicycle ergometer at 120 watts (W) and 60 revolutions per minute (rpm). The subjects were filmed with a cine camera, and pedal reaction forces were recorded from a force transducer mounted in the pedal. The muscular work at the hip, knee and ankle joint was calculated using a model based upon dynamic mechanics described elsewhere. The mean peak concentric power output was, for the hip extensors, 74.4 W, hip flexors, 18.0 W, knee extensors, 110.1 W, knee flexors, 30.0 W and ankle plantar flexors, 59.4 W. At the ankle joint, energy absorption through eccentric plantar flexor action was observed, with a mean peak power of 11.4 W and negative work of 3.4 J for each limb and complete pedal revolution. The energy production relationships between the different major muscle groups were computed and the contributions to the total positive work were: hip extensors, 27%; hip flexors, 4%; knee extensors, 39%; knee flexors, 10%; and ankle plantar flexors 20%.     

Influence of figure skating skates on vertical jumping performance

The purpose of this study was to investigate the influence of wearing figure skating skates on vertical jump performance and interjoint co-ordinations described in terms of sequencing and timing of joint rotations. Ten national to international figure skaters were filmed while performing a squat jump (SJ) on a force platform. Three experimental conditions were successively realized: barefoot (BF), lifting a 1.5 kg weight (LW) corresponding to the skates' mass, attached on the distal extremity of each leg and wearing skates (SK). Jump height, angular kinematics as well as joints kinetics were calculated. Relative to the SJ height reached in the BF condition, SJ performance was significantly decreased by 2.1 and 5.5 cm in the LW and SK conditions, respectively. The restriction of ankle amplitude imposed by wearing skates was found to significantly limit the knee joint amplitude while the hip angular motion was not affected. Neither the skates' mass nor the limited ankle angular motion modified the proximo-distal organization of joint co-ordination observed when jumping barefoot. However, with plantar flexion restriction, the delay between hip and knee extensions increased while it was reduced between knee and ankle extensions. Work output at the knee and ankle joints were significantly lowered when wearing skates. The decrease of work at the knee was shown to result from an early flexing moment causing a premature deceleration of the knee and from a reduction of knee amplitude. Taken together, these results show a minimization of the participation of the knee when plantar flexion is limited. It was proposed that constraining the distal joint causes a reorganization of interjoint co-ordinations and a redistribution of the energy produced by knee extensors to the hip and ankle joints.     

Investigation of muscle tone in patients with Parkinson’s disease in unloading conditions

Parkinson’s disease (PD) is a progressive neurodegenerative disorder, the main symptoms of which are hypertonicity and difficulties emerging during performance of stepping movements due to increased muscle stiffness. Biomechanical (stiffness) and electrophysiological (shortening reaction, SR) characteristics of hip and shank muscles were examined in 25 patients with mild and moderate stages of PD (1 to 3 of Hoehn and Yahr Rating Scale, 61 ± 9 years) and 22 age-matched healthy controls in unloading leg conditions during passive flexion/extension of hip, knee, and ankle joints, as well as the changes in the tonic state of muscles under the influence of levodopa. The data obtained were compared with similar findings in healthy subjects. Essentially greater stiffness in all leg muscle groups (except foot extensors) was observed in patients with PD as compared to the healthy subjects. In patients with PD, SR values in hip and shank extensors as well as in foot flexors and extensors were essentially greater then in the healthy subjects. The medicine essentially reduced the stiffness of hip flexors and knee flexors and extensors. The SR persisted, although the frequency of its occurrence decreased in half of studied muscles, and a significant decrease in the SR value was observed in foot extensors. The medicine had no marked effect on the SR in the proximal muscles. Thus, the increased muscle stiffness in patients with PD manifests itself as distorted reactions to external disturbances and increased reflectory reactions of muscles.     

Inter-segmental coordination: motor pattern in humans stepping over an obstacle with mechanical ankle joint friction

This study examined the influence of a mechanical perturbation of the ankle joint on obstacle avoidance pattern. A decoupled control between the distal joint and the combined (hip-knee) proximal joints was observed according to the task requirement. In this context, a greater mechanical friction at the ankle should be compensated at this joint (local compensation) or alternatively, by regulating more combined proximal joints (knee and/or hip). The leading limb inter-segmental coordination was evaluated in both no constraint and constraint conditions in calculating ranges of motion (ROM), moments of force and powers (from heel-off to obstacle) at the ankle, knee and hip joints. Electromyographic activities were also analyzed. With the constraint, the dorsiflexor moment and the tibialis anterior activity remained unchanged while both ROM and power bursts (absorbed and generated) decreased. The hip and knee ROM remain invariant. At heel-off the absorption by hip extensors decreased and the forthcoming generation by knee flexors increased in the constraint condition. To quantify the inter-joint coordination, principal component analysis was used and indicated a high level of inter-joint coupling (synergy) that decreased with the constraint (i.e. less inter-joint coupling). At the ankle joint, the results suggest that the central command was the same in both conditions thus, not be adapted. At both the hip and knee joints, a combined joints modulation occurred to overcome additional friction.     

Muscular contributions to hip and knee extension during the single limb stance phase of normal gait: a framework for investigating the causes of crouch gait

Crouch gait, a troublesome movement abnormality among persons with cerebral palsy, is characterized by excessive flexion of the hips and knees during stance. Treatment of crouch gait is challenging, at present, because the factors that contribute to hip and knee extension during normal gait are not well understood, and because the potential of individual muscles to produce flexion or extension of the joints during stance is unknown. This study analyzed a three-dimensional, muscle-actuated dynamic simulation of walking to quantify the angular accelerations of the hip and knee induced by muscles during normal gait, and to rank the potential of the muscles to alter motions of these joints. Examination of the muscle actions during single limb stance showed that the gluteus maximus, vasti, and soleus make substantial contributions to hip and knee extension during normal gait. Per unit force, the gluteus maximus had greater potential than the vasti to accelerate the knee toward extension. These data suggest that weak hip extensors, knee extensors, or ankle plantar flexors may contribute to crouch gait, and strengthening these muscles--particularly gluteus maximus--may improve hip and knee extension. Abnormal forces generated by the iliopsoas or adductors may also contribute to crouch gait, as our analysis showed that these muscles have the potential to accelerate the hip and knee toward flexion. This work emphasizes the need to consider how muscular forces contribute to multijoint movements when attempting to identify the causes of abnormal gait.     

Biomechanical analysis of drop and countermovement jumps

For 13 subjects the performance of drop jumps from a height of 40 cm (DJ) and of countermovement jumps (CMJ) was analysed and compared. From force plate and cine data biomechanical variables including forces, moments, power output and amount of work done were calculated for hip, knee and ankle joints. In addition, electromyograms were recorded from five muscles in the lower extremity. The results obtained for DJ appeared to depend on jumping style. In a subgroup of subjects making a movement of large amplitude (i.e. bending their hips and knees considerably before pushing off) the push-off phase of DJ closely resembled that of CMJ. In a subgroup of subjects making a movement of small amplitude, however, the duration of the push-off phase was shorter, values for moments and mean power output at the knees and ankles were larger, and the mean EMG activity of m. gastrocnemius was higher in DJ than in CMJ. The findings are attributed to the influences of the rapid pre-stretch of knee extensors and plantar flexors after touch-down in DJ. In both subgroups, larger peak resultant reaction forces were found at the knee and ankle joints, and larger peak forces were calculated for the Achilles tendon in DJ than in CMJ.     

Effect of squat depth and barbell load on relative muscular effort in squatting

ABSTRACT: Bryanton, MA, Kennedy, MD, Carey, JP, and Chiu, LZF. Effect of squat depth and barbell load on relative muscular effort in squatting. J Strength Cond Res 26(10): 2820-2828, 2012-Resistance training is used to develop muscular strength and hypertrophy. Large muscle forces, in relation to the muscle's maximum force-generating ability, are required to elicit these adaptations. Previous biomechanical analyses of multi-joint resistance exercises provide estimates of muscle force but not relative muscular effort (RME). The purpose of this investigation was to determine the RME during the squat exercise. Specifically, the effects of barbell load and squat depth on hip extensor, knee extensor, and ankle plantar flexor RME were examined. Ten strength-trained women performed squats (50-90% 1 repetition maximum) in a motion analysis laboratory to determine hip extensor, knee extensor, and ankle plantar flexor net joint moment (NJM). Maximum isometric strength in relation to joint angle for these muscle groups was also determined. Relative muscular effect was determined as the ratio of NJM to maximum voluntary torque matched for joint angle. Barbell load and squat depth had significant interaction effects on hip extensor, knee extensor, and ankle plantar flexor RME (p < 0.05). Knee extensor RME increased with greater squat depth but not barbell load, whereas the opposite was found for the ankle plantar flexors. Both greater squat depth and barbell load increased hip extensor RME. These data suggest that training for the knee extensors can be performed with low relative intensities but require a deep squat depth. Heavier barbell loads are required to train the hip extensors and ankle plantar flexors. In designing resistance training programs with multi-joint exercises, how external factors influence RME of different muscle groups should be considered to meet training objectives.     

Power and work produced in different leg muscle groups when rising from a chair

The aim of this study was to determine the power output and work done by different muscle groups at the hip and knee joints during a rising movement, to be able to tell the degree of activation of the muscle groups and the relationship between concentric and eccentric work. Nine healthy male subjects rose from a chair with the seat at knee level. The moments of force about the hip and knee joints were calculated semidynamically. The power output (P) and work in the different muscle groups surrounding the joints was calculated as moment of force times joint angular velocity. Work was calculated as: work = f Pdt. The mean peak concentric power output was for the hip extensors 49.9 W, hip flexors 7.9 W and knee extensor 89.5 W. This power output corresponded to a net concentric work of 20.7 J, 1.0 J and 55.6 J, respectively. There was no concentric power output from the knee flexor muscles. Energy absorption through eccentric muscle action was produced by the hip extensors and hip flexors with a mean peak power output of 4.8 W and 7.4 W, respectively. It was concluded that during rising, the hip and knee muscles mainly worked concentrically and that the greatest power output and work were produced during concentric contraction of the knee and hip extensor muscles. There was however also a demand for eccentric work by the hip extensors as well as both concentric and eccentric work by the hip flexors. The knee flexor muscles were unloaded.     

Isokinetic strength and joint mobility asymmetries in oarside experienced oarsmen

The purpose of the present study was to investigate oarside and nonoarside lower extremity asymmetries in isokinetic strength and joint mobility of port and starboard oarsmen. Peak torques of right and left extensors and flexors were measured on isokinetic dynamometer at angular velocities of 60 and 180°·s-1 in 12 starboard (n = 12; training age 5.55 ± 0.52 years) and 14 port (n = 14; training age 6.09 ± 0.95 years) well-trained male rowers. Mobility of the hip, knee, and ankle joints was measured using the Myrin flexometer, a modification of the Leighton flexometer. The findings indicate that ports had a significantly higher peak torque in oarside right knee extensors at 60°·s-1 (p < 0.001) and 180°·s-1 (p < 0.01) compared to in the nonoarside left knee extensors. In a respective manner, starboards had a higher peak torque in left knee extensors at 60°·s-1 (p < 0.05) and 180°·s-1 (p < 0.05) compared to the right side. Right flexors peak torque was significantly higher in ports compared to that in starboards at 60°·s-1 (p < 0.05) and 180°·s-1 (p < 0.01). No significant difference between port and starboards in left knee flexors at either angular velocity was found. Both port and starboards exhibited a significantly higher hip (p < 0.01) mobility in oarside compared to in nonoarside. We conclude that sweep rowers develop a significantly higher flexion knee peak torque and hip mobility depending on oarside. Strength and mobility abnormalities may provide information for training and rehabilitation. Strengthening and stretching training programs to compensate for potential strength and mobility imbalance and thereby reducing the occurrence of injuries may be designed.     

The relationship between muscle kinetic parameters and kinematic variables in a complex movement

Kinematic variables of the vertical jump (jumping height, jump phase durations and joint angles) were measured on 39 male physical education students. In addition, kinetic parameters of the hip and knee extensors, and of the plantar flexors (maxima voluntary force and its rate of development) were recorded on the same subjects, in isometric conditions. The results demonstrated significant positive correlations between kinetic parameters of the active muscle groups and jumping height (r = 0.217-0.464). The dominant effect on these correlations was due to the knee extensors. Correlations between these parameters and the duration of the jump phases were much weaker. Correlation coefficients between kinetic parameters and limb angles in the lowest body position showed that fast force production in one muscle group was related to a significant decrease in the joint angles of distant body segments. Multiple correlation coefficients between leg extensor parameters and kinematic variables (ranging between 0.256 for the duration of the counter-movement phase and 0.616 for jump height) suggested that kinetic parameters could explain more than a quarter of the variability of this complex human movement. Therefore, the conclusion was drawn that an extended set of measurements of the relevant musculo-skeletal system parameters could predict a considerable amount of the variability of human movement. However, high correlation coefficients between the same kinetic parameters of different muscle groups suggest that not all active muscle groups have to be included in the measurements.     

The role of intersegmental dynamics during rapid limb oscillations

The interactive dynamic effects of muscular, inertial and gravitational moments on rapid, multi-segmented limb oscillations were studied. Using three-segment, rigid-body equations of motion, hip, knee and ankle intersegmental dynamics were calculated for the steady-state cycles of the paw-shake response in adult spinal cats. Hindlimb trajectories were filmed to obtain segmental kinematics, and myopotentials of flexors and extensors at each of the three joints were recorded synchronously with the ciné film. The segmental oscillations that emerged during the paw-shake response were a consequence of an interplay between active and passive musculotendinous forces, inertial forces, and gravity. During steady-state oscillations, the amplitudes of joint excursions, peak angular velocities, and peak angular accelerations increased monotonically and significantly in magnitude from the proximal joint (hip) to the most distal joint (ankle). In contrast to these kinematic relationships, the maximal values of net moments at the hip and knee were equal in magnitude, but of significantly lower magnitude than the large net moment at the ankle joint. At both the ankle and the knee, the flexor and extensor muscle moments were equal, but at the hip the magnitude of the peak flexor muscle moment was significantly greater than the extensor muscle moment. Muscle moments at the hip not only acted to counterbalance accelerations of the more distal segments, but also acted to maintain the postural orientation of the hindlimb. Large muscle moments at the knee functioned to counterbalance the large inertial moments generated by the large angular accelerations of the paw. At the ankle, the muscle moments dominated the generation of the paw accelerations. At the ankle and the knee, muscle moments controlled limb dynamics by slowing and reversing joint motions, and the active muscle forces contributing to ankle and knee moments were derived from lengthening of active musculotendinous units. In contrast to the more distal joints, the active muscles crossing the hip predominantly shortened as a result of the interplay among inertial forces and gravitational moments. The muscle function and kinetic data explain key features of the complex interactions that occur between central control mechanisms and multi-segmented, oscillating limb segments during the paw-shake response.     

The maximal and submaximal vertical jump: implications for strength and conditioning

The vertical jump is a widely used activity to develop explosive strength, particularly in plyometric and maximal power training programs. It is a multijoint action that requires substantial muscular effort from primarily the ankle, knee, and hip joints. It is not known if submaximal performances of a vertical jump have a proportional or differential training effect on the major lower-limb muscles compared to maximal jump performance. Therefore, the purpose of this study was to investigate the contribution that each of the major lower-limb joints makes to vertical jump performance as jump height increases and to comment on the previously mentioned uncertainty. Adult males (N = 20) were asked to perform a series of submaximal (LOW and HIGH) and maximal (MAX) vertical jumps while using an arm swing. Force, motion, and electromyographical data were recorded during each performance and used to compute a range of kinematic and kinetic data, including ankle, knee, and hip joint torques, powers, and work done. It was found that the contribution to jump height made by the ankle and knee joints remains largely unchanged as jump height increases (work done at the ankle: LOW =1.80, HIGH = 1.97, MAX = 2.06 J.kg(-1), F = 3.596, p = 0.034; knee: LOW = 1.62, HIGH = 1.77, MAX = 1.94 J.kg(-1), F = 1.492, p = 0.234) and that superior performance in the vertical jump is achieved by a greater effort of the hip extensor muscles (work done at the hip: LOW = 1.03, HIGH = 1.84, MAX = 3.24 J.kg(-1), F = 110.143, p < 0.001). It was concluded that the role of submaximal and maximal jumps can be differentiated in terms of their effect on ankle, knee, and hip joint muscles and may be of some importance to training regimens in which these muscles need to be differentially trained.     

Comparison of elasticity of human tendon and aponeurosis in knee extensors and ankle plantar flexors in vivo

The purposes of this study were to compare the elasticity of tendon and aponeurosis in human knee extensors and ankle plantar flexors in vivo and to examine whether the maximal strain of tendon was correlated to that of aponeurosis. The elongation of tendon and aponeurosis during isometric knee extension (n = 23) and ankle plantar flexion (n = 22), respectively, were determined using a real-time ultrasonic apparatus, while the participants performed ramp isometric contractions up to voluntary maximum. To calculate the strain values from the measured elongation, we measured the respective length of tendon and aponeurosis. For the knee extensors, the maximal strain of aponeurosis (12.1 +/- 2.8 %) was significantly greater than that of the patella tendon (8.3 +/- 2.4 %), p < 0.001. On the contrary, the maximal strain of Achilles tendon (5.9 +/- 1.4 %) was significantly greater than that of aponeurosis in ankle plantar flexors (2.7 +/- 1.4 %), p < 0.001. Furthermore, for both knee extensors and ankle plantar flexors there was no significant correlation between maximal strain of tendon and aponeurosis. These results would be important for understanding the different roles of tendon and aponeurosis during human movements and for more accurate muscle modeling.     

Standard anthropometric, body composition, and strength variables as predictors of jumping performance in elite junior athletes

The aim of the study was to investigate whether variables routinely assessed while testing athletes can also predict movement performance. The relation between jumping performance and standard strength, anthropometric, and body composition variables was examined in elite junior basketball players. The 33 males were tested for maximal vertical jump, as well as for maximal isometric voluntary force and rate of force development of hip and knee extensors. Standard anthropometric and body composition measures (body height, lean body mass, as well as the percentage of fat and muscle tissue) were also taken. Except for maximal isometric forces (0.38 and 0.52 N.kg(-1) for hip and knee extensors, respectively), all correlation coefficients between the selected variables and jump height were insignificant. As a consequence, the corresponding multiple correlation coefficient, R = 0.71, also suggested a moderate predictability of jumping performance by the standard strength tests and anthropometric and body composition variables. The results obtained dispute the use of the examined tests in sport performance assessment, and also question applying the tests for other purposes such as evaluation of training procedures or selection of young athletes. Therefore, the results are in line with the concept that a reliable performance assessment in homogeneous groups of athletes requires predominantly movement-specific testing.     

The effect of arm swing on lower extremities in vertical jumping

Although it is known that an arm swing can enhance the performance in vertical jumping, the mechanisms through which this enhancement occurs are not yet clearly described. The purpose of this study was to examine how arm swing affects the lower extremity torque, power and work in vertical jumping and to gain an insight into the mechanisms that enable the arm swing to increase jump height. Five subjects maximally performed two types of vertical squat jumps with (SJA) and without (SJ) an arm swing from a force platform. All performances were videotaped with a high-speed video camera (200 Hz). The jump heights, joint torques, power and work were calculated by combining kinematic and kinetic data. It was confirmed that arm swing enhanced the jump height significantly (p<0.01). The work by the hip and by the ankle was significantly augmented by arm swing (p<0.05 and p<0.01, respectively). However, the work by the knee was significantly smaller in SJA (p<0.05). The total work by the three lower extremity joints (ankle, knee and hip) was significantly larger in SJA (p<0.05). The increase of the lower extremity work by the arm swing (31.4 J) was about twice as large as the work done by the shoulder and elbow in SJA (16.3 J). It was concluded that the increment of jump height resulted mainly from the increase of the lower extremity work, which is considered to have been brought about by the additional load on the lower extremity due to the arm swing.     

Optimal muscular coordination strategies for jumping

This paper presents a detailed analysis of an optimal control solution to a maximum height squat jump, based upon how muscles accelerate and contribute power to the body segments during the ground contact phase of jumping. Quantitative comparisons of model and experimental results expose a proximal-to-distal sequence of muscle activation (i.e. from hip to knee to ankle). We found that the contribution of muscles dominates both the angular acceleration and the instantaneous power of the segments. However, the contributions of gravity and segmental motion are insignificant, except the latter become important during the final 10% of the jump. Vasti and gluteus maximus muscles are the major energy producers of the lower extremity. These muscles are the prime movers of the lower extremity because they dominate the angular acceleration of the hip toward extension and the instantaneous power of the trunk. In contrast, the ankle plantarflexors (soleus, gastrocnemius, and the other plantarflexors) dominate the total energy of the thigh, though these muscles also contribute appreciably to trunk power during the final 20% of the jump. Therefore, the contribution of these muscles to overall jumping performance cannot be neglected. We found that the biarticular gastrocnemius increases jump height (i.e. the net vertical displacement of the center of mass of the body from standing) by as much as 25%. However, this increase is not due to any unique biarticular action (e.g. proximal-to-distal power transfer from the knee to the ankle), since jumping performance is similar when gastrocnemius is replaced with a uniarticular ankle plantarflexor.     

The role of hind limb flexor muscles during swimming in the toad, Bufo marinus

Most work examining muscle function during anuran locomotion has focused largely on the roles of major hind limb extensors during jumping and swimming. Nevertheless, the recovery phase of anuran locomotion likely plays a critical role in locomotor performance, especially in the aquatic environment, where flexing limbs can increase drag on the swimming animal. In this study, I use kinematic and electromyographic analyses to explore the roles of four anatomical flexor muscles in the hind limb of Bufo marinus during swimming: m. iliacus externus, a hip flexor; mm. iliofibularis and semitendinosus, knee flexors; and m. tibialis anticus longus, an ankle flexor. Two general questions are addressed: (1) What role, if any, do these flexors play during limb extension? and (2) How do limb flexors control limb flexion? Musculus iliacus externus exhibits a large burst of EMG activity early in limb extension and shows low levels of activity during recovery. Both m. iliofibularis and m. semitendinosus are biphasically active, with relatively short but intense bursts during limb extension followed by longer and typically weaker secondary bursts during recovery. Musculus tibialis anticus longus becomes active mid way through recovery and remains active through the start of extension in the next stroke. In conclusion, flexors at all three joints exhibit some activity during limb extension, indicating that they play a role in mediating limb movements during propulsion. Further, recovery is controlled by a complex pattern of flexor activation timing, but muscle intensities are generally lower, suggesting relatively low force requirements during this phase of swimming.     

Trunk position influences joint activation pattern and physical performance during vertical jumping

Eight well-trained males carried out squat jump and countermovement jump with large (SJL and CMJL) and with small (SJS and CMJS) range of motion to study the influence of trunk position on joint recruitment pattern and jumping height. The main criteria in SJS and CMJS were to maintain trunk in near vertical position during execution. Joint angles, activation time, time at maximum joint velocity for ankle joint, knee joint and hip joint, vertical propulsion time and jumping height were determined using film analysis. The joint activation followed proximal to distal pattern in CMJL, SJL and CMJS, but the pattern was reversed in SJS. The ratio of active state and vertical propulsion time was similar for all joints (63.1 and 72.8%) in CMJL, SJL and CMJS except in SJS where the ratio was significantly less for hip (46.9%) and knee (51.9%). The difference between CMJL and SJL in jumping height was 6.9 ± 2.8 cm which is significantly less than that between CMJS and SJS (14.5 ± 5.3 cm). We concluded that knee joint and hip joint muscles could not contribute to the positive work during the push-off phase when the range of motion is small, the trunk is vertical and the activation level of the muscles is low.     

The EMG activity and mechanics of the running jump as a function of takeoff angle.

To characterize the electromyographic (EMG) activity, ground reaction forces, and kinematics were used in the running jump with different takeoff angles. Two male long jumpers volunteered to perform running jumps at different approach speeds by varying the number of steps (from 3 to 9) in the run-up. Subject TM achieved a greater vertical velocity of the center of gravity (CG) at takeoff for all approach distances. This jumping strategy was associated with greater backward trunk lean at touchdown and takeoff, a lesser range of motion for the thigh during the support phase, more extended knee and ankle angles at touchdown, and a more flexed knee angle at takeoff. Accompanying these differences in kinematics, TM experienced greater braking impulses and lesser propulsion impulses for the forward-backward component of the ground reaction force. Furthermore, TM activated mainly the rectus femoris, vastus medialis, lateral gastrocnemius, and tibialis anterior, while if rarely activated the biceps femoris from just before contact to roughly the first two-thirds of the support phase. These results indicate that TM used a greater takeoff angle in the running jump because he enabled and sustained a greater blocking effect via the coordination patterns of the muscles relative to the hip, knee, and ankle joints. These findings also suggest that the muscle activities recorded in the present experiment are reflected in kinematics and kinetics. Further, the possible influence of these muscle activities on joint movements in the takeoff leg, and their effect on the vertical and/or horizontal velocity of the jump are discussed.