|
Page 2 of 3
METHODS
Participants
With local ethical approval and informed consent 13 practitioners of hard-style martial arts (9 male: 4 female, mean (± SEM) age 23.7 (± 3.1) years and 12 control participants (8 male: 4 female, mean age 22.2 (± 0.6) years were recruited for this study. The martial arts group was composed of 8 who practiced Tae Kwon Do, 3 Shaolin Nam Pai Chauan Kung-Fu and 2 Wu Shu Kwan Kung-Fu. Eleven of the martial artists had black belts and 2 were senior brown belts in training for their black belt. All were in regular training. Participants' height and weight were measured; the dynamometer normalised the torque measurements to the participants' body weight.
Study protocol
Strength testing
Parameters of trunk and lower limb flexion and extension strength were recorded under isometric and isokinetic conditions on a Cybex Norm Isokinetic Testing System (Henley Healthcare, USA).
Leg strength
Each participant was seated comfortably and the knee isolated as much as possible using a strap across the thigh of the leg being tested and a four-strap seat belt to prevent use of thorax and abdominal muscles. The equipment was arranged so that the dynamometer was aligned with centre of rotation of the knee joint being tested. The shin pad was strapped as distally on to the tibia making sure dorsiflexion of the ankle was not restricted. The protocol was repeated for the opposite leg and the order in which the legs were tested was randomised. Participants performed isokinetic concentric knee flexion and extension at speeds of 30, 90 and 210°·s-1 with a trial and five repetitions at each speed with the maximal value being used in the subsequent analysis. This was followed by a maximal isometric contraction in flexion followed by extension at 45° of flexion. Participants were encouraged to be relaxed and a level of verbal encouragement constant for all participants was given throughout testing to prevent "psyching-up", known to affect muscle power (Tod et al., 2003).
Trunk strength
The lower limbs were stabilised by tibial and thigh pads. A belt secured the pelvis to limit the involvement of the hip flexor muscles during testing. Range of motion was recorded from -10° of hyperextension to 80° flexion as recorded through the Cybex system, which represented the limits of range of the system rather than the ranges of the individuals.
Participants performed isokinetic concentric trunk flexion and extension at speeds of 30 and 90°·s-1 with five repetitions at each speed. This was followed by a maximal isometric contraction at +10° flexion, and then at -10° extension.
Measurement of reaction times
All participants performed trials to assess simple reaction time (SRT), choice reaction time (CRT) and their speed of movement once they had reacted in both the SRT (simple movement time; SMT) and CRT (choice movement time; CMT) tasks. Movement times were measured between release of an initiation button and depression of a stop button 25 cm away. Both hands were used in random order to perform the reaction time test by releasing a button in response to a tone. An in-house computer program running on an IBM compatible PC was used to measure reaction and movement times (for full protocol see Davey et al., 2001).
Statistical analyses
Body weight adjusted peak torques under the various conditions were investigated for differences between the left and right legs and also between the martial artists and the controls using the Student's t-test. Reaction and movement times were compared between the dominant hand and the non-dominant hand within the groups and also between the groups using the Student's t-test. Results were considered statistically significant when p < 0.05.
RESULTS
Strength
Leg strength
There were no differences (for either flexion or extension) between the dominant and non-dominant legs for either group under isometric testing or at any of the speeds under isokinetic testing. The data were therefore pooled for both legs. The martial artists had a higher mean body weight adjusted peak isometric torque than the controls only in extension (Figure 1a). Under isokinetic testing the martial artists had a higher torque than the controls in flexion and extension at all speeds (Figure 1b).
The hamstrings/quadriceps torque ratios were not significantly different between the martial artists the controls at any of the isokinetic speeds (mean [± SEM] ratio over all speeds; martial artists 72.67 ± 2.19%, controls 73.33 ± 1.86%).
Trunk strength
There were no significant differences between the martial artists and the controls under isometric testing or at any of the speeds under isokinetic testing for either flexion or extension. However, martial artists did consistently have slightly higher (not significantly) torque for all testing conditions (Figure 2a and Figure 2b).
The flexor/extensor torque ratios were not significantly different between the martial artists the controls at either of the isokinetic speeds (mean [± SEM] ratio over all speeds; martial artists 89.93 ± 6.61%, controls 95.84 ± 3.76%). Concurrent with previous results on isokinetic testing (Chan and Maffulli, 1996; Lord et al., 1992) it can be observed that as the speed of movement increases the peak torque decreases (Figure 1b and Figure 2b).
Reaction times
There were no differences in RT or MT in the simple or choice tests between the dominant and non-dominant hands for either group. The data were therefore pooled for both hands. The RTs for the simple and choice tests were not different between the martial artists and the controls (simple RT for controls = 222.18 ± 6.61ms, martial artists = 210.91 ± 3.75 ms; choice RT for controls = 343.10 ± 15.69ms, martial artists = 312.33 ± 8.77ms). However, the MT was significantly faster in the martial artists for both tests and resulted in a faster total RT for the martial artists (simple MT for controls = 165.79 ± 4.58ms, martial artists = 128.07 ± 3.90ms; choice MT for controls = 197.82 ± 5.23ms, martial artists = 174.29 ± 8.54ms; see Figure 3).
|
Fitness and Nutrition 
(0 vote)
