european college of sport science

Thursday, June 25th, 2009
the change in ankle angle. The Achilles tendon elongation was calculated as the difference between elongations of the MTU and muscle
belly. Negligible muscle activity during the stretching was confirmed through surface electromyograms taken from the medial and lateral
gastrocnemii, soleus, and tibialis anterior muscles during stretching. The fascicle length (FL) was also measured in the mid-belly of the
medial gastrocnemius using ultrasonography.
Results and Discussion: The passive dorsiflexion ROM increased significantly at the 4th week and later from the onset of the stretching
program, which was accompanied by a significant increase in Achilles tendon elongation, especially in the dorsiflexed position. There
was no further increase in muscle belly elongation in the dorsiflexed position. The plantar flexion torque passively attained at rest (0 deg
of ankle joint) decreased significantly, while the FL increased significantly at the 4th week and later. This result indicates that the Achilles
tendon elongation became smaller after the stretching program due to elongated fascicles and the muscle belly at rest at 0 deg of ankle
joint. However, an increase in tendon elongation in the dorsiflexed position after the stretching program suggests a decrease in tendon
stiffness, especially under higher passive tension. In conclusion, these results imply that the 6-week stretching program affects both
mechanical and architectural properties of the gastrocnemius MTU, with different changes of muscular and tendinous components that
are joint angle dependent.
DOES CYCLING INFLUENCE NEUROMUSCULAR CONTROL DURING SUBSEQUENT RUNNING IN LESSER-TRAINED TRI-
ATHLTES?
BONACCI, J., CHAPMAN, A.R., BLANCH, P., VICENZINO, B.
UNIVERSITY OF QUEENSLAND, BRISBANE, AUSTRALIA., MCGILL UNIVERSITY, MONTREAL, CANADA., AUSTRALIAN INSTITUTE OF SPORT, CAN-
BERRA, AUSTRALIA
Triathlon success depends primarily on a triathlete’s ability to run after cycling. As the neuromuscular system effectively translates cardiorespiratory
capacity into efficient movement and therefore into optimal performance, triathletes’ performance relates closely to their ability
to maintain neuromuscular control (muscle recruitment and movement patterns) that is specific to running and not adversely influenced
by the preceding bike-leg1. However, a previous study has shown that running muscle recruitment is influenced by cycling in 36% of
highly-trained triathletes2, despite their years of training. This altered muscle recruitment is due to a direct influence of cycling on neuromuscular
control during running, is independent of fatigue, and is associated with a decrease in running economy and a 2.5 times
greater likelihood of exercise related leg pain3. However, it is not known if cycling has the same direct influence on neuromuscular control
during running in lesser-trained triathletes. PURPOSE To investigate the direct influence of cycling on running muscle activity and
movement patterns in lesser-trained triathletes. METHODS 15 lesser-trained triathletes participated. 3-D kinematics of the pelvis and
lower limbs and recruitment of 11 leg and thigh muscles were compared between a control run (no prior exercise) and a 30 min run that
was preceded by a 15 min cycle (transition run). RESULTS Neuromuscular control was not different between control and transition runs, or
differences were only transient, in most triathletes. Changes in joint position (mean difference of 3°) were evident in 5 triathletes, but these
changes persisted beyond 5 min of running in only 1 triathlete. One triathlete displayed altered recruitment of the biceps femoris muscle
(7.4% decrease in average amplitude over the running stride), which was not associated with a change in kinematics, and persisted for
20 min of the transition run. DISCUSSION Short periods of cycling have no direct influence on running muscle activity in most lesser-trained
triathletes. Muscle recruitment during running was influenced by cycling in only 1 of 15 lesser-trained triathletes (< 7%), compared to 36%
of highly-trained triathletes2, and the magnitude of this change was less than previously reported in highly-trained triathletes (7.4% vs. 10-
20%). Cycling did cause some transient changes to running kinematics in 30% of lesser-trained triathletes. Our findings suggest that
optimal neuromuscular control for running is preserved after cycling in lesser-trained triathletes. The differing influence of cycling on
neuromuscular control during subsequent running in lesser-trained and highly-trained triathletes is likely related to training history.
1Bonacci et al. Sports Medicine. in press
2Chapman et al. (2008) J Sci Med Sport, 11, 371-380
3Chapman et al. (2008) Med Sci Sports Exerc. 40: p. s87
RIGHT OR LEFT – IS THERE AN OPTIMAL INITIAL PRACTICE SIDE IN MOTOR LEARNING?
STÖCKEL, T.
UNIVERSITY OF LEIPZIG
Introduction: Findings from neurosciences indicate, that the two hemispheres in the human brain are specialized for the processing of
distinct movement features (i.e. Serrien, Swinnen & Ivry, 2006). How this knowledge can be useful in motor learning remains unclear. In
the present study two experiments on the acquisition of complex sports motor skills are carried out to prove the relation between the
initial practice side and inherent task de-mands.
Methods
Within a transfer design two groups practiced a novel motor task with same amount of practice on each hand, but in opposite handorder.
Performance changes are measured on both sides separately after a practice period and after a period without practice. In experiment
I subjects were asked to learn a throwing task with high demand on maxi-mum force production. Subjects initially practiced
with their preferred hand and changed to the non-preferred (P-NP) benefited more from practice. In experiment II subjects were asked to
learn a dribbling task with high demand on movement coordina-tion and speed. Subjects initially practiced this task with their nonpreferred
hand before changing to preferred hand (NP-P) benefited more from practice than subjects practiced in opposite order.
Results & Discussion: The results indicate, that tasks with high demand on spatial accuracy and movement coordination are learned
better through initial practice with the non-preferred hand, whereas initial practice with the preferred hand seems to be more efficent for
tasks with high demand on maximum force production. These findings suggest a strong relation between the initial practice side and the
hemispherical specialization for different task demands. The present findings can be used to optimize early motor learning processes.
References
Serrien, D. A., Ivry, R. B. & Swinnen, S. P. (2006). Dynamics of interhemispheric spe-cialization and integration in the context of motor
control. Nature Review Neuroscience, 7, 160-167.
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