Biomedical subjects

M Trolle

Publications and source records attributed to M Trolle.

4 recordsLinked to original sources

PubMed1996

Specificity of training velocity and training load on gains in isokinetic knee joint strength.

The present study investigated the effects of three different strength training regimes on the isokinetic strength profile of the knee extensors (quadriceps, Q) and flexors (hamstrings, H) and if increases in isokinetic strength were accompanied by an enhanced performance during a more complex leg movement, the soccer kick. Twenty-two elite soccer players performed 12 weeks of strength training (three times per week) at either high resistance (HR group: 4 sets, 8 reps, 8RM loading), low resistance (LR group: 4 sets, 24 reps, 24RM loading), loaded kicking movements (LK group: 4 sets, 16 reps, 16RM loading) while one group served as controls (CO group). Isokinetic concentric and eccentric moment of force was obtained (KinCom) as peak moment (Mpeak) and moment at 50 degrees knee flexion (M50) at angular velocities of 30, 120, 240 degrees s-1. Isokinetic knee joint strength was unchanged in groups LR, LK, CO. However, after the HR strength training, concentric Mpeak (+/- SD) increased (P < 0.01) at 30 degrees s-1 (Q, 258 +/- 37 to 297 +/- 57 Nm; H, 122 +/- 22 to 140 +/- 21 Nm). Furthermore, eccentric Mpeak increased at 30, 120 and 240 degrees s-1 (Q, 274 +/- 60 to 345 +/- 57 Nm (P < 0.01), 291 +/- 56 to 309 +/- 49 Nm and 275 +/- 43 to 293 +/- 36 Nm (P < 0.05), respectively; H, 143 +/- 32 to 158 +/- 25 Nm, 152 +/- 39 to 169 +/- 31 Nm and 148 +/- 27 to 163 +/- 19 Nm (P < 0.05)). Corresponding increases (P < 0.05) were observed for M50. The H/Q ratio calculated as eccentric hamstring strength divided by concentric quadriceps strength (Hecc/Qcon, representative for knee extension) at 240 degrees s-1 increased (P < 0.05) from 107 to 118% (based on Mpeak) and from 90 to 105% (M50). Kicking performance estimated by maximal ball flight velocity was unaffected by any of the strength training regimes investigated. In conclusion, only heavy-resistance strength training induced increases in isokinetic muscle strength in the absence of learning effects. Concentric strength gains were observed at the actual velocity of training, while eccentric strength gains were found over the entire range of velocities examined. The capacity of the hamstring muscles for providing stability to the knee joint during fast extension was augmented as a result of the heavy-resistance strength training. Strength training should be integrated with other types of training involving the actual movement pattern in order to increase the performance within more complex movement patterns.

Adult↗

PubMed1995

Isokinetic hamstring/quadriceps strength ratio: influence from joint angular velocity, gravity correction and contraction mode.

This study investigated isokinetic peak- and angle-specific hamstring/quadriceps strength ratios (conventional H/Q ratio) obtained during concentric and eccentric muscle contraction and examined the influence of joint angular velocity and the effect of gravity correction on these ratios. Also, a 'functional' H/Q ratio was defined by calculating eccentric hamstring strength relative to concentric quadriceps strength (Hecc/Qcon' representative for knee extension) and calculating concentric hamstring strength relative to eccentric quadriceps strength (Hcon/Qecc' representative for knee flexion). The H/Q ratio was calculated based on isokinetic peak moment and 50 degree-moment (0 degree = full extension) obtained at joint angular velocities 30, 120 and 240 degrees s-1. Gravity corrected conventional H/Q ratio remained constant across speeds and contraction mode, ranging from 0.47 to 0.54 and from 0.49 to 0.56 based on peak and 50 degree moment, respectively. In contrast, non-corrected H/Q ratio increased during concentric contraction from 0.58 at 30 degrees s-1 to 0.74 at 240 degree s-1 (P < 0.01). For knee extension at 240 degrees s-1 an Hecc/Qcon of 1.05 (peak) and 0.89 (50 degrees) was observed while for flexion at 240 degrees s-1 an Hcon/Qecc of 0.27 (peak) and 0.28 (50 degrees) was observed. In conclusion, gravity correction had high influence on the change in H/Q ratio with variation in extension velocity. A potential 1:1 hamstring/quadriceps strength relationship was demonstrated for fast knee extension, indicating a significant functional capacity of the hamstring muscles for providing muscular stability at the knee joint in such situations.

Adult↗

PubMed1994

Moment and power generation during maximal knee extensions performed at low and high speeds.

In the present study a method was developed to determine knee joint moment and power generated at low to very high velocities of knee extension. A group of 21 male subjects performed maximal knee extensions at four levels of external loading provided by a flywheel system. Knee extension was performed with no restrictions on joint angular velocity and acceleration. An interpolation procedure was employed to obtain moment and power at standard velocities. During each single knee extension peak velocity, peak moment, peak power and moment and power at 50 degrees knee flexion were determined (0 degree = full extension). While maximal recorded angular velocity averaged 693 degrees.s-1 (range 479-1030), maximal recorded moment and power were 226 N.m (157-278) and 1140 W (573-1688), respectively, which were generated at velocities of 55 degrees.s-1 (12-148) and 523 degrees.s-1 (327-846). Isokinetic moment and power were obtained for comparison. The velocity range applied was larger using the flywheel method (21-1030 degrees.s-1 individual range) than that achieved isokinetically (30-240 degrees.s-1). Significant differences were observed between flywheel and isokinetic measurements. These discrepancies may be ascribed to differences in the time course of muscle length change and contractile force generation imposed by the two measuring methods. However, by the nonisokinetic measuring method presently employed, knee extension moment and power could be determined from low to very high angular extension velocity, at loading and contraction conditions comparable to those encountered during sport and exercise.

Adult↗

PubMed1994

Effects of different strength training regimes on moment and power generation during dynamic knee extensions.

This study examined the effect of different training regimes on moment and power generation during maximal knee extensions at low to very high extension velocities (0-1000 degrees.s-1 individual range). A group of 24 soccer players performed 12 weeks of progressively adjusted strength training of the knee extensors at either high resistance (HR, n = 7), low resistance (LR, n = 6), loaded kicking movements (FU, n = 6), while one group served as controls (n = 5). Moment and power generation of the knee extensors were determined before and after the training period with a nonisokinetic measuring method recently described. Following HR training, knee extension moment increased 9%-10% at knee angular velocities 0 (isometric) and 30 degrees.s-1 (P < 0.05), peak moment increased 20% at 240-300 degrees.s-1 (P < 0.05), while power generation increased 5%-29% at 240-480 degrees.s-1 (P < 0.01). In addition, in the HR group maximal recorded power increased 45% (P < 0.01). After FU training a 7%-13% increase in moment and power was observed at 30-180 degrees.s-1 (P < 0.05). Following LR training, peak moment increased 9% at 120 degrees.s-1 (P < 0.05). Improvements in knee extension moment and power were generally related to the angular velocities employed during training. However, as evaluated using the present measuring method, moment and power increased not only at very low but also at high knee angular velocities following the high-resistance strength training.

Adult↗