This study investigates the relationship between peak force and rate of force
development (RFD) obtained from maximal voluntary isometric contraction (MVC) of
the back muscles and the power produced during a loaded lifting task. A group of
27 resistance-trained and 41 recreationally physically active men performed a
maximal isometric strength test of the back muscles and a deadlift to high pull
while lifting progressively increasing weights. Peak RFD correlated
significantly with the peak and mean power produced during a deadlift to high
pull with lower weights (from 20 to 40 kg), with r values
ranging from .941 to .673 and from .922 to .633. The
r2 values ranged from .89 to .45 and from .85 to
.40, explaining 89%–45% and 85%–40% of total variance. There were also
significant relationships between MVC peak force and peak and mean values of
power produced during a deadlift to high pull with weights ≥60 kg
(r in range from .764 to .888 and from .735 to .896). Based
on r2, a moderate-to-high proportion of variance was
explained (58%–79% and 54%–80%). These findings indicate that peak RFD obtained
from MVC of the back muscles may be predictive of power performance during a
lifting task at light loads. In addition to MVC peak force produced by back
muscles, the ability of subjects to develop a high force in a short time should
be evaluated in order to gain deeper insight into a loaded lifting performance,
namely, in those prone to low back pain.
This study evaluates changes in trunk rotational power at different weights and velocities after the preparatory and competitive periods in ice-hockey players, tennis players, and canoeists. The subjects performed trunk rotations to each side with a barbell of different weights placed on the shoulders (6, 10, 12, 16, 20, 22, and 26 kg) prior to and after 6 weeks of the preparatory period and 6 weeks of the competitive period. The results showed that mean power produced in the acceleration phase of trunk rotations increased significantly at weights from 10 to 26 kg or 6 to 26 kg after the preparatory and competitive periods in tennis players. The values obtained during trunk rotations with weights ≥12 kg also increased significantly after the preparatory period in ice-hockey players, whereas there were no significant changes after the competitive period. Similarly, the mean power during trunk rotations with weights ≥10 kg increased significantly only after the preparatory period in canoeists. Similar changes were observed for the peak power. These findings demonstrate that changes in trunk rotational power reflect the specificity of their training programs. This information may provide a basis for designing exercises focused on improvements of power produced during trunk rotations under loading conditions.
Summary:The study evaluates changes of muscle power and velocity during trunk rotations in icehockey players after six weeks of training in competition period. A group of 15 ice-hockey players
This study investigates differences in power and velocity at different loads and power and force at different velocities during trunk rotations in athletes who practice sports with rotational demands on the trunk. Athletes of combat (n = 23), fighting (n = 39), ball (n = 52) and water sports (n = 19) with a mean age of 23.8 ± 1.5 years performed standing trunk rotations on each side with bars of different weights (from 1 kg up to 50 kg) placed on their shoulders. The findings showed significant between-group differences in mean power in the acceleration phase of trunk rotations, especially at higher weights (≥10.5 kg) or lower velocities (≤334.2 rad/s). The power at 10.5 kg was significantly higher in fighting than water (p = 0.035; d = 0.86), combat (p = 0.001; d = 1.53) and ball sports athletes (p = 0.001; d = 1.48), with no significant differences between the two latter groups; at 15.5 kg, it was higher in water than combat (p = 0.027; d = 0.91) and ball sports athletes (p = 0.009; d = 1.17) but not those in fighting sports; and at 20 kg, it was higher in water than combat (p = 0.013; d = 0.98) and ball sports athletes (p = 0.006; d = 1.33), with no significant differences with those in fighting sports. This testing is sensitive in discriminating between athletes of various sports, which may reflect the specificity of their training, including trunk rotations at various velocities under different load conditions.
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