In the trained group, the mean muscle power generated during concentric contractions
of the triceps brachii at a load of 75% of the subject's 1RM was significantly higher during the DS than during the RDS (Figure 3).
The acute exercise based on concentric contractions
was the type that resulted in the highest expressions of HSP70 than horizontal plane (Figure 1) in heart (~180%), kidney (~230%), gastrocnemius (~120%) and soleus (~150%), but not in the lung, suggesting that metabolic stress in the former tissues was more intense at the selected time of six hours post-exercise, the optimal time-point after stress (Jing et al., 2007).
Therefore, the greater concentric contraction
of the quadriceps at a lower angular velocity would compromise the isokinetic tests more significantly in participants with symptomatic PT.
The prestretch allows a greater amount of muscular force to develop during the concentric contraction
. The lack of a prestretch will compromise the full strength potential that can develop from training.
, and a count of 4 for eccentric contractions.
If the motor neuron pool is also inhibited during maximal eccentric contraction, as previous studies have suggested, the attenuation of Ia afferents due to the application of prolonged vibration stimulation might not affect or have less of an effect on the recruitment of high threshold motor units as compared with concentric contraction
. The purpose of the present study is to compare the effect of prolonged vibration on muscle strength and EMG during maximal concentric and eccentric action.
Although the early phase of the concentric contraction
elicited high muscle activity to overcome the load torque, the neuromuscular demand decreased rapidly for the biceps brachii throughout the middle and late phases.
Table 2 showed the mean relative times at four muscle movement stages (i.e., FCC: flexors' concentric contraction
, EEC: extensors' eccentric contraction, ECC: extensors' concentric contraction
, and FEC: flexors' eccentric contraction) at three joints for both groups.
When comparing the inertial requirements to either accelerate (concentric contraction
) or control (eccentric action) the system at the specified velocity, [W.sub.total] differs between these conditions.
Another study investigated test-retest reliability of onset concentric and eccentric EMG activity in stair stepping tasks and showed excellent reliability (ICC 0.91) during concentric contractions
, similar to our findings (Cowan, Bennell, & Hodges, 2000).
Effect of quadriceps femoris muscle length on neural activation during isometric and concentric contractions
. J Appl Physiol 94(3):983-990, 2003.
The isokinetic performance was measured through 5 maximum concentric contractions
of elbow flexion, with the movement held from 0[degrees] to 120[degrees] of flexion at an angular speed of 60[degrees]*[sec.sup.-1].